Patent Application
20210388278
The present disclosure relates generally to processes for producing jet fuels. More particularly, the present disclosure relates to a process for producing synthetic jet fuel.
A process to produce aviation turbine fuel, also referred to as jet fuel, from feedstocks, such as renewable biomass and/or waste feedstocks is of value. Jet fuel is the least likely of the transportation fuels to be replaced by non-hydrocarbon based fuels, such as electricity.
There are challenges in devising a process to produce jet fuel from feedstocks such as renewable and/or waste materials.
A challenge is that of feed logistics related to biomass-to-liquids conversion; for example, as outlined in literature (Zwart, R. W. R.; Boerrigter, H.; Van der Drift, A. Energy Fuels 2006, 20, 2192-2197). Biomass as a representative feedstock is comprised mainly of lignocellulosic matter, and is a raw material that has to be collected over a wide area. Biomass has a low physical density, i.e. in mass per volume, and a low energy density, i.e. combustion energy per volume. Having a centralized processing facility to convert the biomass into jet fuel is typically preferred, but transporting such a low density raw material over large distances can be costly (e.g., both financially and energy-wise), and densification of the biomass before transport is generally required. Feed logistics can be less of a challenge with waste feedstocks, where the collection of waste is normally provided as a service to residents in a community through the sewage system and municipal waste (garbage) collection system.
Another challenge, related to feed logistics, is high water content of feedstocks, such as biomass and waste feedstocks. Although methods for drying and other forms of water removal are known (for example, Allardice, D. J.; Caffee, A. L.; Jackson, W. R.; Marshall, M. In Advances in the science of Victorian brown coal; Li, C-Z. Ed. Elsevier, 2004, p. 85-133), reducing water content to increase energy density can add cost.
Another challenge is feed heterogeneity. With feedstocks that are mainly solid in nature, heterogeneity generally refers to both physical and chemical diversity. When a process is sensitive to feed variation, effort must be expended to homogenize the feedstock, which adds cost.
Another challenge is related to molar ratios of hydrogen, carbon, and oxygen in feedstocks, such as biomass and waste feedstocks. Biomass and waste feedstocks contain oxygen-containing compounds where more than ⅓rd the total mass can be oxygen. This is contrary to fossil crude feedstocks contain little oxygen. When such oxygen-containing feedstocks are converted to jet fuel, the oxygen is generally eliminated with either loss of hydrogen as water, or with loss of carbon as carbon monoxide or carbon dioxide. Jet fuel specifications, however, generally require near complete deoxygenation. Generally, biomass and bio-waste feedstocks generally have a hydrogen-to-carbon molar ratio of about 1.4 to 1, while jet fuel generally requires a higher hydrogen-to-carbon molar ratio of about 2 to 1, a consequence of jet fuel specifications such as smoke point and gravimetric energy density.
Another challenge is related to techniques for refining a biocrude product containing oxygen-containing compounds (oxygenates); for example when present in the <350° C. boiling fraction of the product. Experimental investigations that evaluated operation of petroleum refining technology with oxygenate-containing products indicated that modification of petroleum refining technology is often required, even for hydroprocessing; for example, Leckel, D. O. Energy Fuels 2007, 21, 662-667; Cowley, M. Energy Fuels 2006, 20, 1771-1776; Smook, D.; De Klerk, A. Ind. Eng. Chem. Res. 2006, 45, 467-471. The impact of oxygenates on catalysts and catalysis for refining has been reviewed (for example, De Klerk, A.; Furimsky, E. Catalysis in the refining of Fischer-Tropsch syncrude; Royal Society of Chemistry, 2010). Conventional refineries would likely have to undergo changes in order to utilize biocrude as a feedstock for jet fuel.
In an aspect of the present disclosure, there is provided a process for producing synthetic jet fuel, comprising converting feedstock to synthesis gas; converting the synthesis gas into a mixture comprising liquid hydrocarbons; refining the mixture comprising liquid hydrocarbons to isolate a kerosene product; and hydrotreating the kerosene product to form synthetic jet fuel.
In an embodiment of the present disclosure, there is provided a process wherein converting feedstock to synthesis gas comprises: pyrolyzing the feedstock under aqueous conditions to form a mixture comprising biocrude.
In another embodiment, there is provided a process wherein the feedstock comprises biomass, organic materials, waste streams, or a combination thereof with a high water content.
In another embodiment, there is provided a process wherein converting feedstock to synthesis gas comprises: pyrolyzing the feedstock to form a mixture comprising biocrude.
In another embodiment, there is provided a process wherein the feedstock comprises biomass, organic materials, waste streams, or a combination thereof with a low water content.
In another embodiment, there is provided a process wherein converting feedstock to synthesis gas further comprises: gasifying the mixture comprising biocrude to form the synthesis gas.
In another embodiment, there is provided a process wherein gasifying the mixture comprising biocrude comprises: supercritical water gasification of the mixture comprising biocrude to form a mixture comprising CH4, CO, CO2, and Hz; and reforming the mixture comprising CH4, CO, CO2, and H2 to form the synthesis gas.
In another embodiment, there is provided a process wherein reforming comprises dry reformation and steam reformation.
In another embodiment, there is provided a process wherein when converting feedstock to synthesis gas, the process further comprises: adding an oil feedstock, a sugar feedstock, and/or an alcohol feedstock to the mixture comprising biocrude before gasifying.
In another embodiment, there is provided a process wherein the synthesis gas comprises a H2 to CO ratio that is less than 2 to 1.
In another embodiment, there is provided a process wherein the synthesis gas comprises a stoichiometric ratio of (H2—CO2)/(CO+CO2) that is less than 2 to 1.
In another embodiment, there is provided a process wherein the synthesis gas comprises a Ribblet ratio of (H2)/(2CO+3CO2), that is less than 1 to 1.
In another embodiment, there is provided a process wherein converting the synthesis gas into a mixture comprising liquid hydrocarbons comprises: performing a Fischer-Tropsch synthesis to convert the synthesis gas into a mixture comprising liquid hydrocarbons.
In another embodiment, there is provided a process wherein the Fischer-Tropsch synthesis is performed with an iron-based catalyst.
In another embodiment, there is provided a process wherein when performing the Fischer-Tropsch synthesis to convert the synthesis gas into a mixture comprising liquid hydrocarbons, the process further comprises: a water-gas shift reaction to increase concentration of H2.
In another embodiment, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure of approximately 2 MPa; or at a pressure of greater than 2 MPa; or approximately 2.5 MPa; or approximately 2.8 MPa.
In another embodiment, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure in a range of about 1.5 MPa to 5 MPa; or in a range of about 2 MPa to about 4 MPa; or in a range of about 2 MPa to about 3 MPa; or in a range of about 1.5 to about 2.5 MPs; or in a range of about 2 MPa to about 2.5 MPa.
In another embodiment, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure of greater than 2 MPa.
In another embodiment, there is provided a process wherein the mixture comprising liquid hydrocarbons comprises an alkene to alkane ratio that is great than 1 to 1.
In another embodiment, there is provided a process wherein refining the mixture comprising liquid hydrocarbons to isolate a kerosene product comprises: performing a vapour-liquid equilibrium separation on the mixture comprising liquid hydrocarbons; and separating the mixture into the kerosene product and at least one of an aqueous product, a naphtha and gas product, or a gas oil and heavier product.
In another embodiment, there is provided a process wherein the vapour-liquid equilibrium separation is performed as a single-stage separation and/or a multi-stage separation.
In another embodiment, there is provided a process wherein when an aqueous product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: adding the separated aqueous product to the mixture comprising biocrude before gasifying the mixture comprising biocrude when converting feedstock to synthesis gas.
In another embodiment, there is provided a process wherein, when a naphtha and gas product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: oligomerizing the naphtha and gas product to form a mixture comprising a first additional kerosene product.
In another embodiment, there is provided a process wherein oligomerizing the naphtha and gas product is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another embodiment, there is provided a process wherein oligomerizing the naphtha and gas product is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another embodiment, there is provided a process wherein oligomerizing the naphtha and gas product is performed with a non-sulfided catalyst.
In another embodiment, there is provided a process wherein oligomerizing the naphtha and gas product is performed with an acidic ZSM-5 zeolite catalyst.
In another embodiment, there is provided a process wherein the first additional kerosene product comprises alkene and aromatic compounds.
In another embodiment, there is provided a process wherein the first additional kerosene product comprises approximately 0% to approximately 60% aromatic compounds; approximately 1% to approximately 60% aromatic compounds; or approximately 1% to approximately 50% aromatic compounds; or approximately 1% to approximately 40% aromatic compounds; or approximately 1% to approximately 30% aromatic compounds; or approximately 0% to approximately 1% aromatic compounds; or approximately 1% to approximately 7% aromatic compounds; or approximately 8% to approximately 25% aromatic compounds; or approximately 8% aromatic compounds.
In another embodiment, there is provided a process wherein, when a gas oil and heavier product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: hydrocracking the gas oil and heavier product to form a mixture comprising a second additional kerosene product.
In another embodiment, there is provided a process wherein hydrocracking the gas oil and heavier product is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another embodiment, there is provided a process wherein hydrocracking the gas oil and heavier product is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another embodiment, there is provided a process wherein hydrocracking the gas oil and heavier product is performed with a non-sulfided catalyst.
In another embodiment, there is provided a process wherein the hydrocracking is performed with a noble metal catalyst supported on amorphous silica-alumina. In another embodiment, the catalyst is Pt/SiO2—Al2O3.
In another embodiment, there is provided a process wherein hydrotreating the kerosene product to form synthetic jet fuel comprises: hydrotreating the kerosene product, and when a naphtha and gas product is separated, hydrotreating the first additional kerosene product, to form a mixture comprising paraffinic hydrocarbons; and fractionating the mixture comprising paraffinic hydrocarbons, and when a gas oil and heavier product is separated, fractionating the mixture comprising the second additional kerosene product, to isolate the synthetic jet fuel.
In another embodiment, there is provided a process wherein when fractionating the mixture comprising paraffinic hydrocarbons and fractionating the mixture comprising the second additional kerosene product, the process further comprises: adding the mixture comprising the second additional kerosene product to the mixture comprising paraffinic hydrocarbons before fractionating.
In another embodiment, there is provided a process wherein each of the kerosene product, the first additional kerosene product, and the second additional kerosene product have a normal boiling point temperature range of about 140° C. to about 300° C.
In another embodiment, there is provided a process wherein the hydrotreating is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another embodiment, there is provided a process wherein the hydrotreating is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another embodiment, there is provided a process wherein the hydrotreating is performed with a non-sulfided catalyst.
In another embodiment, there is provided a process wherein the hydrotreating is performed with a reduced base metal catalyst supported on alumina or silica. In another embodiment, the catalyst is reduced Ni/Al2O3.
In another embodiment, there is provided a process wherein the synthetic jet fuel is a semi-synthetic jet fuel, a fully synthetic jet fuel, or a combination thereof.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.
Generally, the present disclosure provides a process for producing synthetic jet fuel, comprising converting feedstock to synthesis gas; converting the synthesis gas into a mixture comprising liquid hydrocarbons; refining the mixture comprising liquid hydrocarbons to isolate a kerosene product; and hydrotreating the kerosene product to form synthetic jet fuel.
In an example of the present disclosure, there is provided a process wherein converting feedstock to synthesis gas comprises: pyrolyzing the feedstock under aqueous conditions to form a mixture comprising biocrude.
In another example, there is provided a process wherein the feedstock comprises biomass, organic materials, waste streams, or a combination thereof with a high water content.
In another example, there is provided a process wherein converting feedstock to synthesis gas comprises: pyrolyzing the feedstock to form a mixture comprising biocrude.
In another example, there is provided a process wherein the feedstock comprises biomass, organic materials, waste streams, or a combination thereof with a low water content.
In another example, there is provided a process wherein converting feedstock to synthesis gas further comprises: gasifying the mixture comprising biocrude to form the synthesis gas.
In another example, there is provided a process wherein gasifying the mixture comprising biocrude comprises: supercritical water gasification of the mixture comprising biocrude to form a mixture comprising CH4, CO, CO2, and H2; and reforming the mixture comprising CH4, CO, CO2, and H2 to form the synthesis gas.
In another example, there is provided a process wherein reforming comprises dry reformation and steam reformation.
In another example, there is provided a process wherein when converting feedstock to synthesis gas, the process further comprises: adding an oil feedstock, a sugar feedstock, and/or an alcohol feedstock to the mixture comprising biocrude before gasifying.
In another example, there is provided a process wherein the synthesis gas comprises a H2 to CO ratio that is less than 2 to 1.
In another example, there is provided a process wherein the synthesis gas comprises a stoichiometric ratio of (H2—CO2)/(CO+CO2) that is less than 2 to 1.
In another example, there is provided a process wherein the synthesis gas comprises a Ribblet ratio of (H2)/(2CO+3CO2), that is less than 1 to 1.
In another example, there is provided a process wherein converting the synthesis gas into a mixture comprising liquid hydrocarbons comprises: performing a Fischer-Tropsch synthesis to convert the synthesis gas into a mixture comprising liquid hydrocarbons.
In another example, there is provided a process wherein the Fischer-Tropsch synthesis is performed with an iron-based catalyst.
In another example, there is provided a process wherein when performing the Fischer-Tropsch synthesis to convert the synthesis gas into a mixture comprising liquid hydrocarbons, the process further comprises: a water-gas shift reaction to increase concentration of H2.
In another example, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure of approximately 2 MPa; or at a pressure of greater than 2 MPa; or approximately 2.5 MPa; or approximately 2.8 MPa.
In another example, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure in a range of about 1.5 MPa to 5 MPa; or in a range of about 2 MPa to about 4 MPa; or in a range of about 2 MPa to about 3 MPa; or in a range of about 1.5 to about 2.5 MPs; or in a range of about 2 MPa to about 2.5 MPa.
In another example, there is provided a process wherein the Fischer-Tropsch synthesis is performed at a pressure of greater than 2 MPa.
In another example, there is provided a process wherein the mixture comprising liquid hydrocarbons comprises an alkene to alkane ratio that is great than 1 to 1.
In another example, there is provided a process wherein refining the mixture comprising liquid hydrocarbons to isolate a kerosene product comprises: performing a vapour-liquid equilibrium separation on the mixture comprising liquid hydrocarbons; and separating the mixture into the kerosene product and at least one of an aqueous product, a naphtha and gas product, or a gas oil and heavier product.
In another example, there is provided a process wherein the vapour-liquid equilibrium separation is performed as a single-stage separation and/or a multi-stage separation.
In another example, there is provided a process wherein when an aqueous product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: adding the separated aqueous product to the mixture comprising biocrude before gasifying the mixture comprising biocrude when converting feedstock to synthesis gas.
In another example, there is provided a process wherein, when a naphtha and gas product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: oligomerizing the naphtha and gas product to form a mixture comprising a first additional kerosene product.
In another example, there is provided a process wherein oligomerizing the naphtha and gas product is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another example, there is provided a process wherein oligomerizing the naphtha and gas product is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another example, there is provided a process wherein oligomerizing the naphtha and gas product is performed with a non-sulfided catalyst.
In another example, there is provided a process wherein oligomerizing the naphtha and gas product is performed with an acidic ZSM-5 zeolite catalyst.
In another example, there is provided a process wherein the first additional kerosene product comprises alkene and aromatic compounds.
In another example, there is provided a process wherein the first additional kerosene product comprises approximately 0% to approximately 60% aromatic compounds; approximately 1% to approximately 60% aromatic compounds; or approximately 1% to approximately 50% aromatic compounds; or approximately 1% to approximately 40% aromatic compounds; or approximately 1% to approximately 30% aromatic compounds; or approximately 0% to approximately 1% aromatic compounds; or approximately 1% to approximately 7% aromatic compounds; or approximately 8% to approximately 25% aromatic compounds; or approximately 8% aromatic compounds.
In another example, there is provided a process wherein, when a gas oil and heavier product is separated, refining the mixture comprising liquid hydrocarbons to isolate a kerosene product further comprises: hydrocracking the gas oil and heavier product to form a mixture comprising a second additional kerosene product.
In another example, there is provided a process wherein hydrocracking the gas oil and heavier product is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another example, there is provided a process wherein hydrocracking the gas oil and heavier product is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another example, there is provided a process wherein hydrocracking the gas oil and heavier product is performed with a non-sulfided catalyst.
In another example, there is provided a process wherein the hydrocracking is performed with a noble metal catalyst supported on amorphous silica-alumina. In another example, the catalyst is Pt/SiO2—Al2O3.
In another example, there is provided a process wherein hydrotreating the kerosene product to form synthetic jet fuel comprises: hydrotreating the kerosene product, and when a naphtha and gas product is separated, hydrotreating the first additional kerosene product, to form a mixture comprising paraffinic hydrocarbons; and fractionating the mixture comprising paraffinic hydrocarbons, and when a gas oil and heavier product is separated, fractionating the mixture comprising the second additional kerosene product, to isolate the synthetic jet fuel.
In another example, there is provided a process wherein when fractionating the mixture comprising paraffinic hydrocarbons and fractionating the mixture comprising the second additional kerosene product, the process further comprises: adding the mixture comprising the second additional kerosene product to the mixture comprising paraffinic hydrocarbons before fractionating.
In another example, there is provided a process wherein each of the kerosene product, the first additional kerosene product, and the second additional kerosene product have a normal boiling point temperature range of about 140° C. to about 300° C.
In another example, there is provided a process wherein the hydrotreating is performed at a pressure of approximately 2.5 MPa; or approximately 2 MPa.
In another example, there is provided a process wherein the hydrotreating is performed at a pressure in a range of about 1.5 MPa to 3 MPa; or in a range of about 1.5 MPa to about 2.5 MPa; or in a range of about 2 MPa to about 2.5 MPa.
In another example, there is provided a process wherein the hydrotreating is performed with a non-sulfided catalyst.
In another example, there is provided a process wherein the hydrotreating is performed with a reduced base metal catalyst supported on alumina or silica. In another example, the catalyst is reduced Ni/Al2O3.
In another example, there is provided a process wherein the synthetic jet fuel is a semi-synthetic jet fuel, a fully synthetic jet fuel, or a combination thereof.
Before explaining the present invention in detail, it is to be understood that the invention is not limited to the exemplary embodiments contained in the present application. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein are for the purpose of description and not of limitation.
It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements or steps. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way, but rather as merely describing an exemplary implementation of the various embodiments described herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
As used in the specification and claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise.
The term “comprising” as used herein will be understood to mean that the list following is non-exhaustive and may or may not include any other additional suitable items, for example one or more further feature(s), component(s) and/or ingredient(s) as appropriate.
As used herein, the terms “about” and “approximately” are used in conjunction with ranges of dimensions, concentrations, temperatures, or other physical or chemical properties and characteristics. Use of these terms is meant to cover slight variations that may exist in the upper and lower limits of the values or ranges of properties and characteristics, for example by ±10%, or ±5%.
As used herein, ‘aviation turbine fuel’ or ‘jet fuel’ refers to kerosene before addition of required fuel additives to meet specification requirements for synthetic aviation turbine fuel as either a jet fuel blend component with petroleum derived kerosene (i.e. semi-synthetic jet fuel), or a jet fuel without any petroleum derived kerosene (i.e. fully synthetic jet fuel). For example, these specification requirements are described in appropriate standards documents, such as the United Kingdom Ministry of Defense. Defense Standard 91-91, Issue 7. Turbine Fuel, Kerosine Type, Jet A-1, NATO Code: F-35, Joint Service Designation: AVTUR; Ministry of Defence: London, 18 Feb. 2011, and ASTM D 7566-15b updated to ASTM D 7566-19 (e.g., see Annex A1, synthesized paraffinic kerosene (SPK) with aromatics). Standard specification for aviation turbine fuel containing synthesized hydrocarbons; American Society for Testing and Materials: West Conshohocken, Pa., 2015. As a skilled person would recognize, only a few of the specification requirements may to be met by adding additives; many of the specification requirements may be met via the refining process (e.g., see Example 4 below, wherein it was possible to meet requirements after adding only a static dissipator).
As used herein, ‘feedstock’ refers to biomass, organic materials, waste streams, or combinations thereof. Examples of feedstocks includes but is not limited to a waste stream from a grain ethanol plant (bagasse, stillage, wastewater and glycerin), cellulosic biomass (wood, energy crops, grasses), organic wastes (green bin collection waste products; sewage sludge), agricultural wastes (agricultural plant wastes or residues, manure), pulp and paper plant waste streams (wood waste, prehydrolysate), municipal-sorted organic wastes, biodiesel (glycerin) and any combinations thereof. Examples of biomass include, but are not limited to materials that are by-products from activities such as forest harvesting, products manufacturing, construction, and demolition debris harvesting or management; and lignocellulosic biomass, for example wood based residues, which are classified into three categories: forest residues, urban residues, and mill residues. Examples of organic materials include, but are not limited to any one of cellulosic materials, lignocellulosic materials, wastes, such as wood processing wastes, agricultural residues, municipal green bin collections, manures, an effluent from a cellulosic material processing plant, an effluent from a paper plant, an effluent from an ethanol-from-biomass process, thin or whole stillage, dry distillers grains, and biodegradable waste waters; materials with carbon and hydrogen in its molecular structure, for example alcohols, ketones, aldehydes, fatty acids, esters, carboxylic acids, ethers, carbohydrates, proteins, lipids, polysaccharides, monosaccharide, cellulose, nucleic acids, etc.; and may be present for example, in waste (e.g. agricultural or industrial waste streams; sewage sludge), organic fluid streams, fresh biomass, pretreated biomass, partially digested biomass, etc. In some examples, ‘feedstock’ as defined herein includes feedstocks with a high water content and/or feedstocks with a low energy density. In some examples, ‘feedstock’ as defined herein includes feedstocks with a low water content.
In some examples, a high water content refers to a material having water present as a separate phase at ambient conditions. In an example, a high water content refers to a material with a water content that exceeds the organic matter content. In other examples, a high water content refers to a water content of, for example, >40 wt %, or, between about 50 wt % to about 95 wt %; or between about 60 wt % to about 90 wt %; or between about 70 wt % to about 90 wt %; or between about 80 wt % to about 90 wt %; or, any value between about 50 wt % and about 70 wt % to any value between about 75 wt % and about 95 wt %. In some examples, a low water content refers to a material without water present as a separate phase at ambient conditions. In other examples, a low water content refers to a water content of, for example, ≤40 wt %, or, between about 5 wt % to about 40 wt %; or between about 10 wt % to about 40 wt %; or between about 20 wt % to about 40 wt %; or between about 30 wt % to about 40 wt %; or, any value between about 5 wt % and about 20 wt % to any value between about 25 wt % and about 40 wt %.
As used herein, ‘oil feedstock’ refers to vegetable oils or animal fat oils. In some examples, ‘oil feedstock’ refers to waste vegetable oils or animal fat oils. ‘Sugar feedstock’ refers to solutions of sugar. In some examples, the sugar may be waste sugar. ‘Alcohol feedstock’ refers to liquid alcohols such as glycerol. In some examples, the liquid alcohol may be a waste alcohol.
As used herein, ‘pyrolyzing feedstock under aqueous conditions’ refers to pyrolysis or thermal treatment of feedstock in the presence of water present as a separate phase at ambient conditions; as such, but not limited to, hydrothermal liquefaction. As used herein, ‘pyrolyzing feedstock’ refers to pyrolysis or thermal treatment of feedstock where water is not present as a separate phase at ambient conditions. As would be recognized by a person of skill in the art, ‘aqueous conditions’ refer to water being present at an amount sufficient to act as, e.g., a reagent, catalyst, solvent, or combination thereof. As a skilled person would also recognize, ‘pyrolyzing conditions’ may refer to the absence of water; or to water being present at an amount that would not be sufficient for acting as, e.g., a reagent, catalyst, solvent, or combination thereof.
As used herein, ‘liquid hydrocarbons’ refers to linear, branched, and/or cyclic alkanes and alkenes (olefins), or aromatic compounds that may be unsubstituted or substituted with oxygen-containing functional groups, such as but not limited to alcohols, aldehydes, carboxylic acids, ketones, ethers, etc.
As used herein, ‘biocrude’ is a mixture that includes but is not limited to aromatic compounds, polyaromatic compounds, fatty acids, alkanes, alkenes, and/or oxygen-containing compounds.
As used herein, ‘paraffinic hydrocarbons’ refers to linear or branched alkanes, and may include cycloalkanes.
Described herein is a process that converts feedstocks, such as biomass, waste feedstocks, oil feedstocks, sugar feedstocks, and/or alcohol feedstock to a synthetic jet fuel that is suitable for blending, or for direct use as a semi-synthetic or fully synthetic jet fuel.
With reference to
Step 1 of
Hydrothermal liquefaction is a process whereby a feedstock is heated under aqueous conditions for a time period sufficient to substantially hydrolyze the feedstock and produce a liquefaction product that has lower average molecular mass than the feed. Hydrothermal liquefaction is an example of a direct liquefaction process. The hydrothermal liquefaction process may be implemented as a batch, semi-batch, or continuous process under subcritical or supercritical water conditions. The operating conditions, supercritical or subcritical, also dictate a minimization of char formation and oxygen contents in the liquefaction product. Some non-condensable gases produced during this process may be used as fuel gases to provide required energy. Hydrothermal liquefaction does not require the feedstock to be dried. Depending on the temperature to which the feedstock is heated, pressure will autogenously develop to limit vaporization of water. Subsequent to hydrothermal liquefaction, a liquid-liquid phase separation may be employed to separate water and liquefaction product. The hydrothermal liquefaction process can be implemented at small-scale to the extent that it can be implemented even on a mobile unit.
In an example of the process as described herein, hydrothermal liquefaction (HTL) is conducted at a temperature of about 350° C. for 40 minutes. Alternatively, it is conducted in supercritical water around 410° C. for only a few minutes (e.g., about 5 minutes or less). As a skilled person would recognize, different hydrothermal liquefaction conditions can create slight different biocrudes, a main difference being the amount of oxygen in the biocrudes: supercritical water HTL can produce biocrudes containing from about 8% to about 10% oxygen, while HTL pyrolysis can produce biocrudes containing oxygen in the low 40% range. The process as described herein can accept all different types of biocrudes/bio oils.
In one example, trailers with mobile liquefaction units (e.g., hydrothermal liquefaction units, or pyrolysis units, etc.) may be parked on farms to process farm waste and biomass to a liquefaction product (e.g., a mixture comprising biocrude) that is collected in a mobile tank for intermittent collection. Such mobile units would typically be designed for simple and unsupervised operation. In another example, larger stationary liquefaction units may be stationed at facilities, such as municipal waste handling facilities and saw or paper mills, where a collection network for biomass and waste feedstocks is already in place. These stationary liquefaction units would typically be designed with more complex heat integration for higher efficiency of operation due to their larger scale. The rest of the process is conducted at a central facility, where the liquefaction product (e.g., a mixture comprising biocrude) is collected from the distributed liquefaction units and processed.
Step 2 of
The term raw synthesis gas refers to a gas that includes a mixture of hydrogen (H2) and carbon monoxide (CO), along with other compounds. The other compounds typically include, but are not limited to carbon dioxide (CO2), water vapor (H2O), and methane (CH4). The term clean synthesis gas refers to raw synthesis gas after removal of potentially detrimental compounds that were present in the raw synthesis gas. The most common class of contaminants that must be removed is sulfur-containing compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS). Additionally other compounds may also be removed during cleaning to improve efficiency of downstream processes.
Employing a mixture comprising biocrude as a feed for raw synthesis gas production, as well as other liquid feeds, such as oil feedstocks, sugar feedstocks, and/or alcohol feedstocks, can reduce the impact of feed heterogeneity by blending in a feed tank (see unit 2.1 in
In an example of the process as described herein, the raw synthesis gas is produced by supercritical water gasification (SCWG). With SCWG and the appropriate amount of water with respect to the carbon/hydrogen/oxygen content, heat required for the gasification is generated within a reactor by the SCWG exothermic reactions once the gasification has been started by an external heat source, such as a start-up furnace. As such, SCWG does not require a constant source of external heat, while excess water requires some external heat. Further, the SCWG reactor operates at a lower temperature, and without a need to employ an externally supplied oxidant. Water in the SCWG reactor gives up some of its hydrogen, typically through the water-gas shift reaction, to increase the hydrogen-to-carbon ratio in the raw synthesis gas above that generally anticipated from gasification of the liquid feeds alone. All feed materials are introduced into the SCWG process in the liquid phase at high pressure, generally above pressure requirements of a synthesis gas feed for a Fischer-Tropsch synthesis, which is both energy efficient, and less complex than compressing the raw synthesis gas after being produced. Hot gas coming out of the SCWG reactor exchanges heat with incoming feedstock, and water vapors in the gas are cooled/condensed along with other water soluble organic compounds, and separated in pressurized liquid/gas separators. Part of the separated water-rich product is recycled back into the SCWG process. At this point, the raw synthesis gas may still contain compounds other than hydrogen and carbon monoxide. Some of these compounds may be removed by condensation, but some gas cleaning (see unit 2.3 in
In an example of the process as described herein, supercritical water gasification (SCWG) is conducted at a temperature in the range of 570° C. to 590° C., with a water content of about 30% to about 60%, and at a pressure in the range of about 20 MPa to about 30 MPa, or about 22.5 MPa to about 25 MPa. In another example, supercritical water gasification (SCWG) is conducted at a temperature of about >550° C., with the pressure being dependent on reactor design and means for pressure control.
In some examples of step 2, reforming is used in conjunction with clean synthesis gas production to convert hydrocarbons present in the clean synthesis gas to hydrogen and carbon monoxide. Presence of enough methane in raw synthesis gas, along with carbon dioxide, allow reformation of these gases using steam reforming and dry reforming. This also allows for recycling of additional CO2 from the raw synthesis gas to maximize conversion of the methane into carbon monoxide and hydrogen. Some carbon dioxide and water is also produced in the formation processes. Water may be separated by cooling the gases, and carbon dioxide may be reduced in a synthesis gas clean up unit.
In its simplest form, the reactions of steam reforming and dry methane reforming, along with the water-gas shift and reverse water-gas shift reactions during step 2 are as follows:
CH4+CO22CO+2H2 1.
CH4+2H2OCO+3H2 2.
CO2+H2CO+H2O 3.
CO+H2OCO2+H2 4.
Optionally, the use of a water-gas shift converter may be considered to change the molar ratio of hydrogen-to-carbon monoxide in the clean synthesis gas. At least some of the potential technologies that could be selected for step 3 may benefit from a hydrogen to carbon monoxide molar ratio that is closer to 2 to 1. Optionally, production of clean synthesis gas is followed by removal of some CO2 from the clean synthesis gas. Part of the CO2 could be recycled.
More particularly,
Step 3 of
In its simplest form, the main reactions during step 3 for Fischer-Tropsch synthesis can be represented by the following Equations 1-6, where Equation 6 is relevant only in iron-catalyzed Fischer-Tropsch synthesis:
Alkenes: nCO+2nH2→(CH2)n+nH2O (1)
Alkanes: nCO+(2n+1)H2→H(CH2)nH+nH2O (2)
Alcohols: nCO+2nH2→H(CH2)nOH+(n−1)H2O (3)
Carbonyls: nCO+(2n−1)H2→(CH2)nO+(n−1)H2O (4)
Carboxylic acids: nCO+(2n−2)H2→(CH2)nO2+(n−2)H2O (5)
Water gas shift: CO+H2OCO2+H2 (6)
The value of n in Equations 1 to 6 depends on the probability of chain growth. The probability of chain growth, or alpha-value, depends on the nature and operation of the Fischer-Tropsch catalyst. The product distribution is reasonably well represented by an Anderson-Schulz-Flory distribution. With the Fischer-Tropsch synthesis of the herein described process, products from the Fischer-Tropsch synthesis will typically have carbon numbers in the range of n=1 to 100, although some products with n>100 may form.
In an example of step 3, iron-catalyzed Fischer-Tropsch synthesis is employed for conversion of synthesis gas to product mixture comprising liquid hydrocarbons. Iron-catalyzed Fischer-Tropsch syntheses does not require the synthesis gas composition to be adjusted to meet the hydrogen-to-carbon monoxide usage ratio of approximately 2 to 1, because iron-based Fischer-Tropsch catalysts are capable of performing the water-gas shift reaction. In an example, iron-catalyzed Fischer-Tropsch synthesis is performed at a temperature of 240° C. and higher, or at a temperature in a range 240 to 280° C. Operating the Fischer-Tropsch synthesis at a higher temperature allows the exothermic heat of reaction to be removed by high-pressure steam production, typically to generate steam at a pressure of 4 M Pa or higher.
In another example of step 3, the iron-based Fischer-Tropsch synthesis is performed with a synthesis gas that has a hydrogen-to-carbon monoxide ratio less than 2 to 1. In another example, the iron-based Fischer-Tropsch synthesis is performed with a synthesis gas that has a stoichiometric ratio, (H2—CO2)/(CO+CO2), of less than 2 to 1. In another example, the iron-based Fischer-Tropsch synthesis is performed with a synthesis gas that has a Ribblet ratio, (H2)/(2 CO+3 CO2), of less than 1 to 1. In another example, the design of the Fischer-Tropsch synthesis is such that the mixture comprising liquid hydrocarbons from the Fischer-Tropsch synthesis has an alkene to alkane ratio that is greater than 1 to 1. Said alkene to alkane ratio being greater than 1 to 1 is generally desired for the process as described herein given that, as the alkene:alkane ratio decreases, oligomerization can be affected (e.g. the oligomerization yield can be decreased), which can reduce the ability to produce fully synthetic jet.
In another example, the design of the Fischer-Tropsch synthesis is such that the once-through carbon monoxide conversion of synthesis gas during Fischer-Tropsch synthesis is high, typically higher than 80% and more preferably higher than 90%. In another example, the design of the Fischer-Tropsch synthesis is such that steam is fed to the Fischer-Tropsch synthesis as necessary for the reaction to proceed without excessive carbon formation.
Following is a more detailed description of an example of step 3 of
Step 4 of
Following is a more detailed description of an example of step 4 of
The relationship between the streams shown in
Step 5 of
The straight run gas and naphtha product (4b in
In its simplest form, the main reactions during operation of the oligomerization process can be represented by the following Equations 7-9:
Oligomerization/cracking: CxH2x+CyH2yC(x+y)H(2x+2y) (7)
Aromatization: alkenes→aromatics+alkanes (8)
Aromatic alkylation/dealkylation: (C6H5)CxH(2x+1)+CyH2y(C6H5)C(x+y)H(2x+2y+1) (9)
In addition to the reactions in Equations 7-9, there are various reactions involving oxygen-containing compounds, such as dehydration and ketonization, which may take place. The reactions described are not intended to be exhaustive, but are provided for illustrative purposes. The relative prevalence of these reactions depends on the temperature and pressure conditions of the oligomerization process. Through manipulation of the operating conditions in the oligomerization process, it is possible to produce a kerosene material that enables the blending of fully synthetic jet fuel from the process described herein. By operating at least part of the oligomerization catalyst at a temperature and pressure that favors aromatization (Equation 8), the total amount of aromatics can be manipulated to increase or decrease the amount of fully synthetic jet fuel in relation to semi-synthetic jet fuel produced by the process described herein. In one example, a non-sulfided catalyst, such as an unpromoted ZSM-5 catalyst is used.
In an example of the oligomerization process as described herein, operating temperatures in a range or about 200° C. to about 320° C. would generally produce a product useful as a blend material for production of semi-synthetic jet fuel, because it would be an isoparaffinic kerosene after hydrotreatment (e.g., see Examples 1 and 4). Operating temperatures of about >320° C. (nominally about 320° C. to about 400° C.) would typically be used to produce a product with more aromatics, which would be suitable for blending fully synthetic jet fuel after hydrotreating to saturate the olefins (e.g., see Examples 2 and 5). In some examples, in both cases, pressure can be varied over a wide range, e.g. about 0.1 MPa to about 20 MPa.
Generally, the process as described herein can be operated at a pressure commensurate to, or slightly lower than the Fischer-Tropsch synthesis as described herein, e.g. around 2 MPa, despite operation at higher pressure generally being easier due to the higher partial pressure of olefins. Operating at a pressure commensurate to, or lower than the Fischer-Tropsch synthesis as described herein, without requiring prior separation to remove unconverted synthesis gas, avoids separation and recompression in the process as described herein.
In another example, the oligomerization process uses the gaseous product stream 411 (
The product from the oligomerization process (e.g., a mixture comprising a first additional kerosene product) comprises unconverted material and new products. The unconverted material comprises hydrogen, carbon monoxide and paraffinic hydrocarbons. The new products have a boiling range distribution spanning gas, naphtha and distillates, material ranging from normally gaseous compounds to compounds with a normal boiling point temperature up to 360° C. The new products include a first additional kerosene product. The first additional kerosene product comprises olefinic and aromatic compounds. The ratio of olefinic to aromatic compounds depends on the operating conditions of the oligomerization process. This flexibility in adjusting the ratio of olefinic to aromatic compounds facilitates production of semi-synthetic jet fuel and production of fully synthetic jet fuel. The additional kerosene product (see 5a in
In one example, the olefinic and aromatic compounds outside the boiling range of kerosene are recovered as products. In another example, some or all of the olefinic and aromatic compounds outside the boiling range of kerosene are recycled to the oligomerization process. In another example, some or all of the olefinic and aromatic products outside the boiling range of kerosene are sent to the hydrotreater.
The unconverted material from the oligomerization process may at least be employed as source of hydrogen for the hydrocracker and hydrotreater. The nature of gas treatment downstream of the oligomerization involves processes known to those skilled in the art of gas treating, such as hot carbonate absorption to remove carbon dioxide, and pressure swing adsorption to recover hydrogen.
The kerosene product (see 4c in
Following is a more detailed description of an example of the oligomerization unit in step 5 of
Stream 511 is separated in 520. In one example, stream 511 is separated to produce a gaseous product 521, an organic liquid product 522, and a water-rich liquid product 523. This type of separation may be achieved by decreasing the temperature to condense part of 511, which can then be separated in a three-phase vapor-liquid-liquid separator. Another way to achieve this type of separation is to employ a device with more than one equilibrium stage. Another way to achieve this type of separation is to use a device that employs liquid absorption. Stream 521 can be applied in various ways. One potential use of stream 521 is as fuel gas. Another potential use of stream 521 is to recycle part or all of 521 to either the Fischer-Tropsch synthesis or the synthesis gas production. In an example, stream 521 is treated as shown in
Stream 614 is further separated in unit 620. Unit 620 is employed to recover part of the hydrogen present in 614 as stream 621, the remainder of the material being in stream 622. One of the technologies commonly employed for the separation in 620 is pressure swing adsorption, which would produce H2 in stream 621 as a high purity hydrogen stream. The hydrogen in stream 621 would be employed for use in units 5.2 and 5.3 shown in
Optionally, the organic liquid product 522 can be further separated. This option is depicted in
The gas oil and heavier product (see 4d in
In another example of the process as described herein, the hydrocracker is operated at a lower pressure than the Fischer-Tropsch synthesis to enable direct use of hydrogen recovered from the unconverted product after the oligomerization process (e.g., see Example 3). Generally, hydrocracking is performed at about 350° C. to about 400° C., and at pressures of >3 MPa (e.g., typical mild hydrocracking at pressures of about 5-8 MPa and typical severity hydrocracking at pressures of about 10-20 MPa). However, as is demonstrated in Example 3 (see below), hydrocracking as described herein was performed using a pressure of <3 MPa (e.g., about 2 MPa), at a temperature of about 320° C. In some examples, hydrocracking as described herein can be performed at a temperature of about 320° C. to about 400° C., or about 320° C. to about 380° C., or about 320° C. to about 350° C. In other examples, hydrocracking as described herein can be performed at a pressure of about 1 MPa to about 20 MPa, or about 1 MPa to about 15 MPa, or about 1 MPa to about 10 MPa, about 1 MPa to about 5 MPa, or about 1 MPa to about 3 MPa, or about 1 MPa to about 2 MPa.
Following is a more detailed description of an example of the hydrocracking unit in step 5 of
The hydrogen feed and hydrogen recycled system of the hydrocracker unit 540 is not explicitly shown. The hydrogen loop of hydrocracking technology is known in the art (for example, Scherzer, J.; Gruia, A. J. Hydrocracking science and technology; CRC Press: Boca Raton, Fla., 1996). The hydrogen feed for the hydrocracker can be obtained from stream 621 in
Product stream 541 is separated in different fractions in separator unit 550. Optionally, the product from the hydrotreater, unit 5.3 in
Stream 551 can be further separated into product fractions and sold as propane, butanes, and naphtha. This material may also be used for subsurface recovery of bitumen from oil sands deposits. The naphtha may be used as blend material for motor-gasoline, or as refinery feed or petrochemical feed. The naphtha may be employed as diluent for oil sands derived bitumen, or in processes such as paraffinic froth treatment for bitumen recovery. Stream 552 is used for semi-synthetic jet fuel. Stream 553 may be sold as a diesel fuel blend component and will typically have a cetane number of equal or better than 51, contain no sulfur, and have acceptable cold flow properties. Stream 554 can be sold as lubricant base oil blend component, zero sulfur fuel oil, or synthetic oil.
The feed materials (e.g., the kerosene products) that are sent to the hydrotreater are hydrogenated to substantially convert olefinic and oxygen-containing molecules to paraffinic molecules. The product after hydrotreating is fractionated to obtain final products. The kerosene fraction is fractionated to be suitable as aviation turbine fuel.
In an example, a non-sulfided, reduced base metal supported on alumina, or silica catalyst is used to perform hydrotreating in a fixed bed reactor. An example of a reduced base metal supported on alumina catalyst is a reduced Ni/Al2O3 catalyst. Making use of a reduced metal (e.g., hydrotreating) catalyst instead of a sulfided base metal (e.g, hydrotreating) catalyst allows addition of sulfur to the feed to be avoided, and allows reactions such as the hydrotreating to be performed at milder conditions than with a sulfided base metal (e.g., hydrotreating) catalyst. In some examples, the hydrotreater is operated at a temperature of about 80° C. to about 200° C., or about 80° C. to about 180° C., or about 80° C. to about 150° C. In other examples, the hydrotreater is operated at a temperature of about 180° C. to about 420° C., or about 180° C. to about 380° C., or about 260° C. to about 380° C. In an example, the hydrotreater is operated at a lower pressure than the Fischer-Tropsch synthesis to enable direct use of hydrogen recovered from the unconverted product after the oligomerization process. In other examples, the hydrotreater is operated at a pressure of about 0.5 MPa to about 20 MPa, or about 1 MPa to about 15 MPa, or about 1 MPa to about 10 MPa, about 1 MPa to about 5 MPa, or about 1 MPa to about 3 MPa, or about 1 MPa to about 2 MPa. In another example of hydrotreating as described herein, it was found that, using a model feed (10% 1-hexene, 5% toluene, 85% n-octane), near complete conversion of olefins was possible at about 80° C. and about 1 MPa with reduced Ni/Al2O3.
A major product from the herein described process is a kerosene range material that meets the specification requirements for synthetic aviation turbine fuel, either as a semi-synthetic jet fuel blend component or a fully synthetic jet fuel.
Following is a more detailed description of an example of the hydrotreating unit in step 5. The hydrotreating unit in step 5 is depicted in more detail in
The product from hydrotreating is stream 561. The product in stream 561 is substantially free from alkenes and oxygen-containing organic compounds. The product in stream 561 consists of mainly alkanes, cycloalkanes, and aromatics, the relative abundance of each compound class depends on both the operation of the hydrotreater unit 560, and the composition of the feed materials to the hydrotreater. When the feed material to the hydrotreater unit 560 comprises only of stream 532, it is likely that all of stream 561 is suitable for use as either fully synthetic jet fuel, or semi-synthetic jet fuel. Stream 561 is suitable as fully synthetic jet fuel when the aromatic content of stream 561 is between 8 and 25 vol %, and the distillation range of stream 532 is appropriately selected in accordance with jet fuel specifications. The here described process provides a refining process to produce a fully synthetic jet fuel from a Fischer-Tropsch product (i.e., the mixture comprising liquid hydrocarbons) that employs only two conversion steps, the oligomerization unit 510 and the hydrotreater unit 560.
Stream 561 is suitable as a semi-synthetic jet fuel when the aromatic content is lower, and the distillation range of stream 532 is appropriately selected in accordance with jet fuel specifications. The herein described process provides a refining process to produce a semi-synthetic jet fuel from a Fischer-Tropsch product (i.e., the mixture comprising liquid hydrocarbons) that employs only two conversion steps, the oligomerization unit 510 and the hydrotreater unit 560.
Optionally, and irrespective of the composition of the feed materials going to the hydrotreater unit 560, stream 561 may be separated in unit 550 as shown in
In some examples, it is possible to operate the oligomerization process in such a way that little or no aromatics are produced. This type of operation is useful for increasing semi-synthetic jet fuel production (and extending catalyst cycle life time). In a specific example, the aromatic content is 8% or more, for example up to about 60%, the stream may be useful for fully synthetic jet fuel production, either on its own, or as a blend with one of the other kerosene streams that do not contain aromatics. Preferably, the fully synthetic jet fuel will have between 8 and 25% aromatics. In some examples, the aromatic content is less than 8%. In other examples, the aromatic content is about 0 to 1%. In this example, the stream may be useful as blend component for semi-synthetic jet fuel, with some of the pre-approved synthetic jet fuel classes (isoparaffinic kerosenes) having <1% aromatics.
In examples of the process as described herein, the overall process generates a sufficient amount of H2 to conduct each process step that requires H2 as a reactant/input (e.g., as depicted in any one of
In other examples of the process as described herein, the final output of the process—jet fuel having a high boiling point (e.g., between 140° to 260°) and a low freezing point (e.g., <−60° C.)—is produced in high yield. In some examples, the process as described herein produces more jet fuel having a high boiling point (e.g., between 140° to 260°) and a low freezing point (e.g., <−60° C.) than other, incumbent or standard technologies.
In other examples of the process as described herein, use of a gas compressor(s) between the Fischer-Tropsch unit (e.g., unit 3.1 in
Following is a more detailed description of other examples of the final refining steps of the process as described herein; particularly oligomerization (e.g., unit 5.1 in
Example 1—Semi Synthetic Jet Fuel, 50% Blend. A fixed bed continuous flow reactor was employed to produce an olefinic kerosene range product in accordance with, for example, oligomerization unit 5.1 in
In this example the reactor was operated on a once-through basis. The conversion of light olefins, using propylene as example, was >95%. The mass selectivity to >140° C. material, which could potentially be suitable to inclusion in a jet fuel blend, was 29%. As was previously described (Garwood, W. E. ACS Symp. Ser. 1983, 218, 383-396), the carbon number distribution over H-ZSM-5 is determined by the combination of temperature and pressure. An engineering approach that may be employed to increase overall yield of the >140° C. fraction, is to have an internal recycle of naphtha (C5−140° C.) to an oligomerization reactor. This was not done in the present example, as it was already known.
Olefinic product from the oligomerization was hydrotreated over a reduced, non-sulfided Ni/Al2O3 catalyst to an olefin content of <1%. For example, the hydrotreater is unit 5.3 in
It is noteworthy that all of the distillation cuts in the 140-260° C. boiling range met the maximum onset of freezing point specification of Jet A-1, which is −47° C. It is typically difficult to obtain (e.g., using incumbent or standard technologies) a product having a high boiling point (e.g., between 140° to 260°) and a low freezing point (e.g., <−60° C.). This supports that the process as described herein is capable of maximizing jet fuel yield.
Example 2—Full Synthetic Jet Fuel, 100% Blend. The process has the potential to produce material that will enable formulation of fully synthetic jet fuel, with no petroleum-derived material. One of the requirements for fully synthetic jet fuel is that it must contain 8-25 vol % aromatics. In this example, a fixed bed continuous flow reactor was employed to produce an olefinic and aromatic kerosene range product in accordance with, for example, oligomerization unit 5.1 in
The olefinic and aromatic product from the oligomerization reactor was hydrotreated over a reduced, non-sulfided Ni/Al2O3 catalyst to an olefin content of <1%, but at conditions that would not substantially hydrogenate the aromatics to cycloparaffins. For example, the hydrotreater is unit 5.3 in
All of the distillation cuts in the 140-260° C. boiling range met the maximum onset of freezing point specification of Jet A-1, which is −47° C. The higher density of the distillation cuts in Table 2 (compared with Table 1) was indicative of aromatics and cycloparaffins in the hydrotreated product. Typically, the aromatics content of synthetic jet fuel is from a fossil fuel source. In contrast, operating, e.g., unit 5.1 in
Example 3. This example illustrates the performance of the hydrocracking unit, e.g., unit 5.2 in
The feed material to the hydrocracker was wax, representative of, e.g., stream 4d in
Hydrocracked product separation did not reflect any separation strategy for the process, and narrow cuts were prepared for the same reason as described in Example 1. The density and onset of freezing point were determined for each of the narrow boiling fractions in the hydrocracked product (Table 3).
The narrow distillation cuts in the 140-250° C. boiling range had an onset of freezing that met the maximum onset of freezing point specification of Jet A-1 of −47° C.
Example 4. A semi-synthetic jet fuel was blended using products described in Examples 1 and 3, together with a kerosene range product from a petroleum refinery. The kerosene range product from the petroleum refinery was re-distilled to remove the lighter than 150° C. boiling material. The remaining petroleum-derived kerosene was characterized, and had a density of 817.5 kg/m3, with an onset of freezing of −51° C.
A semi-synthetic jet fuel was prepared. The blend consisted of 25 vol % of the 160-260° C. fraction of the hydrotreated oligomerization product shown in Table 1, 25 vol % of the 160-240° C. fraction of the hydrocracked product shown in Table 3, and 50 vol % of the petroleum-derived kerosene. Considering the properties previously listed, a wider boiling range could have been used, but the purpose was to demonstrate that a viable semi-synthetic jet fuel could be produced by the process as described herein. The blend was not optimized to maximize the yield of jet fuel.
The semi-synthetic jet fuel prepared in this way was characterized and compared to Jet A-1 specification requirements (Table 4). A fuels laboratory performed the characterization, and added 1 mg/L Stadis 450 to the semi-synthetic jet fuel before characterization. This was the only commonly used additive as prescribed for jet fuel use that was added. The standard test methods and specifications listed in Table 4 were the methods and specifications as prescribed for the evaluation of Jet A-1 aviation turbine fuel.
In addition to those specifications listed in Table 4, cold flow density and viscosity of the semi-synthetic jet fuel was measured. At −20° C., the density was 816 kg/m3, the viscosity was 3.75 mPa·s (cP), and the dynamic viscosity was 4.58 mm2/s (cSt). The maximum allowable dynamic viscosity at −20° C. is 8 mm2/s (cSt). All of the tested parameters passed the detailed requirements for a semi-synthetic Jet A-1 as described by the ASTM D7566-18a standard specification for aviation turbine fuel containing synthesized hydrocarbons.
The flash point temperature of 50.0° C. (minimum 38° C. required) and density of 790.7 kg/m3 (minimum 775 kg/m3 required), indicated that additional lower boiling material could be accommodated in the semi-synthetic jet fuel blend. The onset of freezing point of −56.3° C. (maximum −47° C. required), density of 790.7 kg/m3 (maximum 840 kg/m3 required), smoke point of 23.0 mm (minimum 18 mm required), and final boiling point temperature of 261.0° C. (maximum 300° C. required), indicated that additional higher boiling material could accommodated in the semi-synthetic jet fuel blend.
Example 5. The process as described herein is also capable of producing a fully synthetic jet fuel blend. Unlike a semi-synthetic jet fuel, fully synthetic jet fuel has no petroleum-derived blend component in the jet fuel blend.
A fully synthetic jet fuel was blended using products described in Examples 2 and 3. The blend consisted of 40 wt % of the 160-260° C. fraction of the hydrotreated oligomerization product shown in Table 2, and 60 wt % of the 160-240° C. fraction of the hydrocracked product shown in Table 3. This fully synthetic jet fuel was characterized and compared to Jet A-1 specification requirements (Table 5). A fuels laboratory performed the characterization, and added 1 mg/L Stadis 450 to the fully synthetic jet fuel before characterization.
In addition to those specifications listed in Table 5, the cold flow density and viscosity of the fully synthetic jet fuel was measured. At −20° C., the density was 812 kg/m3, the viscosity was 3.27 mPa·s (cP), and the dynamic viscosity was 4.02 mm2/s (cSt). The maximum allowable dynamic viscosity at −20° C. is 8 mm2/s (cSt). For those analyses that were performed, the fully synthetic jet fuel passed the requirements for synthetic Jet A-1 as described by the ASTM D7566-18a standard specification for aviation turbine fuel containing synthesized hydrocarbons.
The T50−T10=(197.8−181.7)=16.1° C., which is larger than the minimum difference of 15° C. required for a fully synthetic jet fuel. The T90−T10=41.1° C., which is larger than the minimum difference of 40° C. required for a fully synthetic jet fuel. The flash point temperature of 47.0° C. (minimum 38° C. required) and density of 786.1 kg/m3 (minimum 775 kg/m3 required), indicated that additional lower boiling material could accommodated in the fully synthetic jet fuel blend. The onset of freezing point of −72.2° C. (maximum −47° C. required), density of 786.1 kg/m3 (maximum 840 kg/m3 required), smoke point of 24.0 mm (minimum 18 mm required), and final boiling point temperature of 242.9° C. (maximum 300° C. required), indicated that additional higher boiling material could accommodated in the fully synthetic jet fuel blend.
The embodiments described herein are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.
All publications, patents and patent applications mentioned in this Specification are indicative of the level of skill those skilled in the art to which this invention pertains and are herein incorporated by reference to the same extent as if each individual publication patent, or patent application was specifically and individually indicated to be incorporated by reference.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modification as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
This application claims priority to U.S. Provisional patent application No. 62/798,636, filed Jan. 30, 2019, the entire contents of which is hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2020/050111 | 1/30/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62798636 | Jan 2019 | US |
