Patent Application
20220275286
The present invention generally relates to systems and methods for producing aromatics and olefins. More specifically, the present invention relates to systems and methods for producing aromatics and olefins via catalytic cracking naphtha in dense phase riser reactors.
BTX (benzene, toluene, and xylene) are a group aromatics that are used in many different areas of the chemical industry, especially the plastic and polymer sectors. For instance, benzene is a precursor for producing polystyrene, phenolic resins, polycarbonate, and nylon. Toluene is used for producing polyurethane and as a gasoline component. Xylene is feedstock for producing polyester fibers and phthalic anhydride. In the petrochemical industry, benzene, toluene, and xylene are conventionally produced by catalytic reforming of naphtha.
Over the last few decades, the demand for aromatics, especially BTX, has been consistently increasing. One of the conventional methods of producing BTX includes steam cracking hydrocarbon feeds such as naphtha. However, the overall efficiency for this conventional method is relatively low. Besides aromatics, other products including olefins, which compete with aromatics in the process, are also produced. Furthermore, a large amount of hydrocarbons in the effluent are recycled to the steam cracking unit. As hydrocarbons have to be hydrogenated before they are recycled back to the steam cracking unit, the large amount of hydrocarbons for recycling can demand a large amount of hydrogen and energy in the hydrogenation process, resulting in high production cost.
Another conventional method for producing aromatics (e.g., BTX) includes catalytic cracking of naphtha in a fluidized bed. However, these conventional fluidized bed reactors are generally operated with low average solid volume fraction and low gas-solids contact efficiency due to the limitation of superficial gas velocities in the fluidized bed. Thus, the products of the conventional methods often include a high methane content produced from thermal cracking of hydrocarbons, resulting in increased production cost for aromatics.
Overall, while methods of producing light olefins exist, the need for improvements in this field persists in light of at least the aforementioned drawbacks of the methods.
A solution to at least some of the above-mentioned problems associated with the production process for aromatics (e.g., BTX) using naphtha as the feed material has been discovered. The solution resides in a method of producing aromatics and olefins that includes using one or more dense phase riser reactors to catalytically crack naphtha. The superficial gas velocity in one or more of the dense phase riser reactors is significantly higher than the conventional methods. This can be beneficial for at least providing high solid volumetric fraction in each of the riser reactors, thereby reducing the occurrence of thermal cracking of the naphtha. Additionally, the lift gas used in the dense phase riser reactor does not contain steam. Thus, zeolite based catalyst, which has higher efficiency than non-zeolite based catalyst, can be used and is not subject to de-alumination by steam. Moreover, this method allows for sufficient back mixing in the dense phase riser reactors, as characterized by wide residence time distribution (RTD) with relative variance of greater than 0.33, resulting in improved BTX to olefins ratio in the effluent from the dense phase riser reactors. Therefore, the method of the present invention provides a technical solution to at least some of the problems associated with the currently available methods for producing aromatics mentioned above.
Embodiments of the invention include a method of producing aromatics and/or olefins. The method comprises contacting, in a dense phase riser reactor with an average solids volume fraction of at least 0.08, naphtha with catalyst particles under reaction conditions sufficient to produce a first product comprising one or more olefins and/or one or more aromatics. The dense phase riser reactor is operated such that superficial gas velocity therein is in a range of 4 to 20 m/s. The method further comprises flowing a mixture of the first product, the catalyst particles, and unreacted naphtha to a cyclone system disposed in a secondary reactor. The secondary reactor is stacked on top of a regenerator. The method further comprises separating, in the cyclone system, the first product from the catalyst particles. The method further still comprises stripping, in a stripper disposed in the regenerator, hydrocarbon vapor from the catalyst particles to produce stripped catalyst particles. The method further still comprises regenerating, in the regenerator, the stripped catalyst particles.
Embodiments of the invention include a method of producing aromatics and/or olefins. The method comprises contacting, in a dense phase riser reactor, naphtha with catalyst particles under reaction conditions sufficient to produce a first product comprising one or more aromatics and/or one or more olefins. The dense phase riser reactor is operated such that superficial gas velocity therein is in a range of 4 to 20 m/s. The dense phase riser reactor has an internal diameter in a range of 2.0 to 2.75 m. The solids volume fraction (SVF) in the dense phase riser reactor is in a range of 0.1 to 0.2. The method further comprises flowing a mixture of the first product, the catalyst particles, and unreacted naphtha to a cyclone system disposed in a secondary reactor. The secondary reactor is stacked on top of a regenerator. The method further comprises separating, in the cyclone system, the first product from the catalyst particles. The method further still comprises stripping, in a stripper disposed in the regenerator, hydrocarbon vapor from the catalyst particles to produce stripped catalyst particles. The method further still comprises regenerating, in the regenerator, the stripped catalyst particles.
Embodiments of the invention include a reaction unit for producing olefins and/or aromatics. The reaction unit comprises one or more dense phase riser reactors. Each of the dense phase riser reactors comprises a housing, a feed inlet disposed on a lower half of the housing, adapted to receive a feed material into the housing, a lift gas inlet disposed on lower half of the housing, adapted to receive a lift gas into the housing, a catalyst inlet disposed on the lower half of the housing, adapted to receive catalyst into the housing, and an outlet disposed on the top half of the housing, adapted to release an effluent of the dense phase riser from the housing. The reaction unit further comprises a secondary reactor in fluid communication with the outlet of each dense phase riser reactor. The secondary reactor comprises one or more cyclones adapted to separate the effluent of the dense phase riser(s) into a gaseous stream comprising gaseous products and a solid stream comprising the catalyst. The reaction unit further still comprises a regenerator in fluid communication with the secondary reactor, adapted to receive the solid stream from the secondary reactor and regenerate the catalyst of the solid stream. The regenerator is in fluid communication with the catalyst inlet of each dense phase riser reactor.
The following includes definitions of various terms and phrases used throughout this specification.
The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.
The terms “wt. %”, “vol. %” or “mol. %” refer to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material is 10 mol. % of component.
The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.
The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and/or the specification, include any measurable decrease or complete inhibition to achieve a desired result.
The term “effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.
The use of the words “a” or “an” when used in conjunction with the term “comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”
The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.
The process of the present invention can “comprise,” “consist essentially of,” or “consist of” particular ingredients, components, compositions, etc., disclosed throughout the specification.
The term “primarily,” as that term is used in the specification and/or claims, means greater than any of 50 wt. %, 50 mol. %, and 50 vol. %. For example, “primarily” may include 50.1 wt. % to 100 wt. % and all values and ranges there between, 50.1 mol. % to 100 mol. % and all values and ranges there between, or 50.1 vol. % to 100 vol. % and all values and ranges there between.
Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.
For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Currently, aromatics, especially BTX, and light olefins can be produced by steam cracking or catalytic cracking of naphtha. However, the overall conversion rate to BTX and/or light olefins for steam cracking naphtha is relatively low. Furthermore, the production costs for steam cracking naphtha are high as steam cracking of naphtha produces a large amount of raffinate, which needs to be hydrogenated before it is recycled back to the steam cracking unit.
Thus, the large amount raffinate results in high demand for hydrogen and energy in the hydrogenation process. Conventional processes of catalytically cracking naphtha generally have a relatively low superficial gas velocities and extremely high catalyst to oil ratio in the catalyst bed, which leads to challenges to maintain pressure balance in the reactor. Furthermore, the conventional catalytic cracking of naphtha uses steam as lift gas, which prevents using zeolite based catalyst, which has a high catalytic efficiency for BTX and light olefins. The present invention provides a solution to at least some of these problems. The solution is premised on a method including catalytically cracking naphtha in a reaction unit that comprises one or more dense phase riser reactors. This method is capable of retaining high solid volumetric fraction along with a high superficial gas velocity in the dense phase riser reactors, thereby reducing the thermal cracking of naphtha and increasing yields of BTX and/or light olefins. Moreover, this method includes sufficient back mixing of the catalyst and hydrocarbons in the dense phase riser reactors. Thus, the selectivity to aromatics (e.g., BTX) is increased over conventional methods. Additionally, this method uses a lift gas that does not contain steam such that zeolite based catalyst can be used in the reaction unit, resulting in improved BTX and light olefins production efficiency. These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.
In embodiments of the invention, a reaction unit for producing aromatics and olefins via catalytic cracking of naphtha comprises one or more dense phase riser reactors, a secondary reactor for gas-solid separation, and a regenerator. With reference to
In embodiments of the invention, housing 102 is made of carbon steel, refractory, or combinations thereof. Housing 102 is adapted to host catalytic cracking of naphtha. According to embodiments of the invention, feed inlet 103 may be disposed at lower half of housing 102 and adapted to receive a feed stream therein. In embodiments of the invention, the feed stream includes naphtha. In embodiments of the invention, lift gas inlet 104 is disposed at lower half of housing 102 and adapted to receive a lift gas stream in housing 102. In embodiments of the invention, lift gas inlet 104 may be disposed below feed inlet 103. The lift gas stream may include nitrogen, methane, any inert gas, or combinations thereof. In embodiments of the invention, catalyst inlet 105 is disposed on lower half of housing 102. Catalyst inlet 105 may be adapted to receive catalyst particles into housing 102. Non-limiting examples for the catalyst particles may include zeolite. According to embodiments of the invention, the catalyst particles have a particle size in a range of 75 to 120 μm and all ranges and values there between including ranges of 75 to 78 μm, 78 to 81 μm, 81 to 84 μm, 84 to 87 μm, 87 to 90 μm, 90 to 93 μm, 93 to 96 μm, 96 to 99 μm, 99 to 102 μm, 102 to 105 μm, 105 to 108 μm, 108 to 111 μm, 111 to 114 μm, 114 to 117 μm, and 117 to 120 μm. The catalyst particles have a density in a range of 1000 to 1700 kg/m3 and all ranges and values there between including ranges of 1000 to 1100 kg/m3, 1100 to 1200 kg/m3, 1200 to 1300 kg/m3, 1300 to 1400 kg/m3, 1400 to 1500 kg/m3, 1500 to 1600 kg/m3, 1600 to 1700 kg/m3. In embodiments of the invention, catalyst inlet 105 may be disposed above lift gas inlet 104. According to embodiments of the invention, lift gas inlet 104 is disposed below feed inlet 103 and catalyst inlet 105.
In embodiments of the invention, each dense phase riser reactor 101 may be substantially cylindrical. Dense phase riser reactor 101 may have a height to diameter ratio in a range of 8 to 27 and all ranges and values there between including ranges of 8 to 9, 9 to 11, 11 to 13, 13 to 15, 15 to 17, 17 to 19, 19 to 21, 21 to 23, 23 to 25, and 25 to 27. In embodiments of the invention, each dense phase riser reactor 101 has an inner diameter in a range of 2.0 to 2.75 m and all ranges and values there between. According to embodiments of the invention, each dense phase riser reactor 101 comprises outlet 106 in fluid communication with secondary reactor 107 such that an effluent of dense phase riser reactor 101 flows from dense phase riser reactor 101 to secondary reactor 107.
Effluent from dense phase riser reactor 101 may include unreacted naphtha, aromatics, light olefins, lift gas, spent catalyst particles, and any other by-products. According to embodiments of the invention, secondary reactor 107 is adapted to separate the effluent from dense phase riser reactor(s) 101 into a product gas stream and a spent catalyst stream. The product gas stream may include unreacted naphtha, aromatics, light olefins, lift gas, byproducts, or combinations thereof. Spent catalyst stream may include spent catalyst particles, hydrocarbons absorbed on the spent catalyst particles, lift gas, or combinations thereof.
According to embodiments of the invention, secondary reactor 107 comprises secondary reactor housing 108 and one or more cyclones 109 adapted to separate the effluent from riser reactor 108 into spent catalyst particles and product gas. In embodiments of the invention, each cyclone 109 in secondary reactor 107 is single- or multiple-stage cyclone. Each cyclone 109 may be in fluid communication with a dipleg. The dipleg is adapted to transfer catalyst particles from the cyclone to the dense bed close to the bottom of secondary reactor 107. In embodiments of the invention, the dipleg for each cyclone 109 is further in fluid communication with a splash plate and/or a trickle valve. The splash plate and/or trickle valve may be adapted to avoid bypass of gas up the dipleg of a cyclone.
In embodiments of the invention, a bottom end of secondary reactor 107 may be in fluid communication with regenerator 110 such that spent catalyst stream flows from secondary reactor 107 to catalyst regenerator 110. In embodiments of the invention, regenerator 110 is adapted to strip hydrocarbons absorbed on the spent catalyst and regenerate the spent catalyst after the stripping process. Regenerator 110 may be further adapted to separate flue gas from the catalyst. According to embodiments of the invention, secondary reactor 107 is stacked on top of regenerator 110 such that the spent catalyst particles can directly flow from secondary reactor 107 to regenerator 110 without any additional driving force other than gravity.
According to embodiments of the invention, regenerator 110 comprises stripper 111 configured to strip hydrocarbons absorbed on the spent catalyst particles. Stripper 111 may comprise a stripping gas sparger 112 configured to release stripping gas for contacting the spent catalyst. Non-limiting examples for the stripping gas can include nitrogen, methane, flue gas, and combinations thereof. Stripper 111 may further comprise stripper internals 113 configured to enhance counter-current contacting between the down-flowing emulsion phase stream and the up-flowing bubbles stream in fluidized bed strippers. Stripper internals 113 may include disk structured internals, chevron structured internals, packing internals, subway grating internals, or combinations thereof. Stripper internals 113 may further comprise standpipe 114 adapted to transfer catalyst particles from stripper 111 to regenerator 110 and a slide valve adapted to control flow rate of catalyst particles from stripper 111 to regenerator 110. In embodiments of the invention, catalyst regenerator 110 further comprises air inlet 115 in fluid communication with air sparger 116 that is disposed in catalyst regeneration unit 112 such that air is supplied into regenerator 110 through air inlet 115 and air sparger 116. According to embodiments of the invention, catalyst regenerator 110 further comprises one or more cyclones (e.g., cyclone 118) adapted to separate flue gas from the catalyst. The flue gas may include the flue gas produced during the catalyst regeneration process. According to embodiments of the invention, catalyst regenerator 110 comprises one or more catalyst outlets 117, each of which is in fluid communication with catalyst inlet 105 of each dense phase riser reactor 101 such that regenerated catalyst flows from catalyst regenerator 110 to each dense phase riser reactor 101. In embodiments of the invention, secondary reactor 107, stripper 111, and regenerator 110 are operated with multiple dense phase riser reactors 101.
Methods of producing aromatics and olefins via catalytic cracking naphtha have been discovered. Embodiments of the method are capable of increasing solid volume fraction in the reaction unit, and minimizing occurrence of thermal cracking of hydrocarbons compared to conventional methods of catalytic cracking. Therefore, the methods may be able to significantly improve production efficiency of aromatics and olefins compared to conventional methods. As shown in
According to embodiments of the invention, as shown in block 201, method 200 may include contacting, in dense phase riser reactor(s) 101, naphtha with catalyst particles under reaction conditions sufficient to produce a first product comprising one or more aromatics and/or one or more olefins. In embodiments of the invention, the contacting at block 201 includes injecting, into dense phase riser reactor 101, the lift gas through lift gas inlet 104, naphtha through feed inlet 103, and/or catalyst through catalyst inlet 105 such that the catalyst particles and the naphtha make contact with each other and the materials in dense phase riser reactor 101 move upwards. In embodiments of the invention, the naphtha at the contacting step of block 201 comprises hydrocarbons with a final boiling point lower than 350° C. In embodiments of the invention, first reaction conditions at block 201 may include a superficial gas velocity (SGV) in a range of 4 to 20 m/s and all ranges and values there between including ranges of 4 to 5 m/s, 5 to 6 m/s, 6 to 7 m/s, 7 to 8 m/s, 8 to 9 m/s, 9 to 10 m/s, 10 to 11 m/s, 11 to 12 m/s, 12 to 13 m/s, 13 to 14 m/s, 14 to 15 m/s, 15 to 16 m/s, 16 to 17 m/s, 17 to 18 m/s, 18 to 19 m/s, and 19 to 20 m/s. The reaction conditions at block 201 may include a reaction temperature of 670 to 730° C. and all ranges and values there between including ranges of 670 to 675° C., 675 to 680° C., 680 to 685° C., 685 to 690° C., 690 to 695° C., 695 to 700° C., 700 to 705° C., 705 to 710° C., 710 to 715° C., 715 to 720° C., 720 to 725° C., and 725 to 730° C. The reaction conditions at block 201 may further include a reaction pressure of 1 to 3 bar and all ranges and values there between including ranges of 1 to 1.5 bar, 1.5 to 2.0 bar, 2.0 to 2.5 bar, and 2.5 to 3.0 bar. The reaction conditions at block 201 may further include an average residence time in dense phase riser reactor 101 of 1 to 3 s and all ranges and values there between including ranges of 1 to 1.5 s, 1.5 to 2.0 s, 2.0 to 2.5 s, and 2.5 to 3.0 s. The reaction conditions at block 201 may further include a weighted hourly space velocity in a range of 0.3 to 3 hr−1 and all ranges and values there between including ranges of 0.3 to 0.6 hr−1, 0.6 to 0.9 hr−1, 0.9 to 1.2 hr−1, 1.2 to 1.5 hr−1, 1.5 to 1.8 hr−1, 1.8 to 2.1 hr−1, 2.1 to 2.4 hr−1, 2.4 to 2.7 hr−1, and 2.7 to 3.0 hr−1.
According to embodiments of the invention, at block 201, a solid volume fraction (SVF) for a fluidized catalyst bed in dense phase riser reactor 101 may be in a range of 0.1 to 0.2 and all ranges and values there between including ranges of 0.11 to 0.12, 0.12 to 0.13, 0.13 to 0.14, 0.14 to 0.15, 0.15 to 0.16, 0.16 to 0.17, 0.17 to 0.18, 0.18 to 0.19, and 0.19 to 0.20. According to embodiments of the invention, the catalyst of dense phase riser reactor 101 includes zeolite. At block 201, each dense phase riser reactor 101 may be operated at a catalyst bed bulk density of 120 to 240 kg/m3 and all ranges and values there between including ranges of 120 to 130 kg/m3, 130 to 140 kg/m3, 140 to 150 kg/m3, 150 to 160 kg/m3, 160 to 170 kg/m3, 170 to 180 kg/m3, 180 to 190 kg/m3, 190 to 200 kg/m3, 200 to 210 kg/m3, 210 to 220 kg/m3, 220 to 230 kg/m3, and 230 to 240 kg/m3.
According to embodiments of the invention, at block 201, the lift gas and the naphtha are flowed into dense phase riser reactor at a volumetric ratio of 0.4 to 0.8 and all ranges and values there between including ranges of 0.4 to 0.5, 0.5 to 0.6, 0.6 to 0.7, and 0.7 to 0.8. Each dense phase riser reactor 101 may include a catalyst bed having a catalyst to oil ratio of 10 to 50 (based on weight) and all ranges and values there between including ranges of 10 to 12, 12 to 14, 14 to 16, 16 to 18, 18 to 20, 20 to 22, 22 to 24, 24 to 26, 26 to 28, 28 to 30, 30 to 32, 32 to 34, 34 to 36, 36 to 38, 38 to 40, 40 to 42, 42 to 44, 44 to 46, 46 to 48, and 48 to 50.
According to embodiments of the invention, as shown in block 202, method 200 further includes flowing an effluent from each dense phase riser reactor 101 including a mixture of the first product, the catalyst particles, and unreacted naphtha to a cyclone system disposed in secondary reactor 107. The effluent from each dense phase riser reactor 101 may further include the lift gas. In embodiments of the invention, the flowing at block 202 is propelled by the lift gas. Non-limiting examples of the lift gas may include nitrogen, methane, any inert gas, steam, or combinations thereof.
According to embodiments of the invention, as shown in block 203, method 200 may further comprise separating the first product from the catalyst particles in the cyclone system of secondary reactor 107. In embodiments of the invention, the separation at block 203 includes gas-solid separation to produce a gas product stream and a solid catalyst stream. According to embodiments of the invention, the gas product stream comprises the first product. In embodiments of the invention, the first product includes unreacted naphtha, BTX (benzene, toluene, xylene), light olefins (C2 and C3 olefins), lift gas, by-products, or combinations thereof. The first product may have a BTX to light olefins weight ratio of 0.25 to 0.45 and all ranges and values there between including ranges of 0.25 to 0.30, 0.30 to 0.35, 0.35 to 0.40, and 0.40 to 0.45. The yield of BTX may be in a range of 13 to 17% and all ranges and values there between including ranges of 13 to 14%, 14 to 15%, 15 to 16%, and 16 to 17%. The separating at block 203 may include passing the effluent of dense phase riser reactor 101 through one or more cyclones of secondary reactor 107. In embodiments of the invention, the product gas stream comprises 13 to 17 wt. % BTX.
According to embodiments of the invention, as shown in block 204, method 200 includes stripping, in stripper 111 disposed in regenerator 110, hydrocarbon vapor from the catalyst particles to produce stripped catalyst particles. In embodiments of the invention, the hydrocarbon vapor is absorbed on the catalyst particles before the stripping at block 204. In embodiments of the invention, at block 204, a volumetric ratio of stripping gas to catalyst particles is in a range of 0.02 to 0.65 and all ranges and values there between including ranges of 0.02 to 0.05, 0.05 to 0.08, 0.08 to 0.11, 0.11 to 0.14, 0.14 to 0.17, 0.17 to 0.20, 0.20 to 0.23, 0.23 to 0.26, 0.26 to 0.29, 0.29 to 0.32, 0.32 to 0.35, 0.35 to 0.38, 0.38 to 0.41, 0.41 to 0.44, 0.44 to 0.47, 0.47 to 0.50, 0.50 to 0.53, 0.53 to 0.56, 0.56 to 0.59, 0.59 to 0.62, and 0.62 to 0.65.
According to embodiments of the invention, as shown in block 205, method 200 includes regenerating, in regenerator 110, the stripped catalyst particles. In embodiments of the invention, at block 205, the catalyst particles are regenerated in the presence of air. The regenerating at block 205 may be conducted at a regeneration temperature of 680 to 750° C. and all ranges and values there between including ranges of 680 to 690° C., 690 to 700° C., 700 to 710° C., 710 to 720° C., 720 to 730° C., 7300 to 740° C., and 740 to 750° C. In embodiments of the invention, the regenerating at block 205 produces regenerated catalyst and flue gas. The flue gas may be separated from the regenerated catalyst in cyclone(s) 118. In embodiments of the invention, the regenerated catalyst is flowed to each dense phase riser reactor 101 through catalyst outlet 117.
Although embodiments of the present invention have been described with reference to blocks of
As part of the disclosure of the present invention, a specific example is included below. The example is for illustrative purposes only and is not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.
Experiments on the production of BTX and light olefins via catalytic cracking were conducted a in pilot-scale reaction unit of the present invention. The dense-phase riser reactor in the pilot-scale reaction unit was operated with high solid volume fractions and high backing mixing to maximize aromatics yields. The composition of the feedstock used in these experiments are shown in Table 1.
The reaction conditions for the reaction unit included a reaction temperature of 680° C., a catalyst regeneration temperature 700° C., a reaction pressure of 1.50 atm, a catalyst to oil ratio of 30, a weight hourly space velocity (WHSV) of 1.9 h−1, and a catalyst load of 1500 g. The results of the experiments are shown in Table 2.
The results show that high BTX yields can be obtained in a reactor operated under conditions comprising short contact times, high solids volume fractions, and high backmixing in the reactors.
In the context of the present invention, at least the following 17 embodiments are described. Embodiment 1 is a method of producing aromatics. The method includes contacting, in a dense phase riser reactor, naphtha with catalyst particles under reaction conditions sufficient to produce a first product containing one or more olefins and/or one or more aromatics, wherein the dense phase riser reactor is operated such that superficial gas velocity therein is in a range of 4 to 20 m/s. The method further includes flowing a mixture of the first product, the catalyst particles, and unreacted naphtha to a cyclone system located in a secondary reactor, wherein the secondary reactor is stacked on top of a regenerator. The method still further includes separating, in the cyclone system, the first product from the catalyst particles. The method also includes stripping, in a stripper located in the regenerator, hydrocarbon vapor from the catalyst particles to produce stripped catalyst particles, and regenerating, in the regenerator, the stripped catalyst particles. Embodiment 2 is the method of embodiment 1, wherein the dense phase riser reactor has an internal diameter in a range of 2.0 to 2.75 m. Embodiment 3 is the method of either of embodiments 1 or 2, wherein the dense phase riser reactor includes a fluidized bed with a solids volume fraction (SVF) in a range of 0.1 to 0.2. Embodiment 4 is the method of any of embodiments 1 to 3, wherein the stripper and the regenerator are operated with a plurality of dense phase riser reactors. Embodiment 5 is the method of any of embodiments 1 to 4, wherein the one or more dense phase riser reactors are operated using a lift gas selected from the group consisting of nitrogen, methane, any inert gas, and combinations thereof. Embodiment 6 is the method of embodiment 5, wherein the lift gas contains less than 10 wt. % steam. Embodiment 7 is the method of any of embodiments 1 to 6, wherein the catalyst contains particles of average diameter in a range of 75 to 120 μm. Embodiment 8 is the method of any of embodiments 1 to 7, wherein the catalyst has a particle density of 1000 to 1400 kg/m3. Embodiment 9 is the method of any of embodiments 1 to 8, wherein the first product contains unreacted naphtha, aromatics, light olefins, lift gas, by-products, or combinations thereof. Embodiment 10 is the method of any of embodiments 1 to 9, wherein the reaction conditions include a reaction temperature in a range of 670 to 730° C. Embodiment 11 is the method of any of embodiments 1 to 10, wherein the reaction conditions include a weight hourly space velocity of 0.3 to 3 hr−1 and an average residence time of 1 to 5 s. Embodiment 12 is the method of any of embodiments 1 to 11, wherein the dense phase riser reactor includes a fluidized bed having a catalyst to oil weight ratio of 10 to 50. Embodiment 13 is the method of any of embodiments 1 to 12, wherein the dense phase riser reactor is operated at a volumetric feed to lift gas ratio of 1.25 to 2.5.
Embodiment 14 is a reaction unit for producing aromatics. The reaction unit includes one or more dense phase riser reactors, wherein each of the dense phase riser reactors includes a housing and a feed inlet located on a lower half of the housing, adapted to receive a feed material into the housing. The reaction unit further includes a lift gas inlet located on bottom of the housing, adapted to receive a lift gas into the housing. The reaction unit still further includes a catalyst inlet located at the bottom of the housing, adapted to receive catalyst into the housing. The reaction unit also includes an outlet located on top of the housing, adapted to release an effluent of the dense phase riser from the housing. In addition, the reaction unit includes a secondary reactor in fluid communication with the outlet of each dense phase riser reactor, wherein the secondary reactor includes one or more cyclones adapted to separate the effluent of the dense phase riser(s) into a gaseous stream containing gaseous products and a solid stream containing a catalyst. The reaction unit further includes a regenerator in fluid communication with the secondary reactor, adapted to receive the solid stream from the secondary reactor and regenerate the catalyst of the solid stream, wherein the secondary reactor is stacked on top of the regenerator and the regenerator is in fluid communication with the catalyst inlet of each dense phase riser reactor. Embodiment 15 is the reaction unit of embodiment 14, wherein the catalyst regeneration unit further includes a stripper adapted to strip hydrocarbons absorbed on catalyst particles of the solid stream using a stripping gas before the catalyst is regenerated. Embodiment 16 is the reaction unit of embodiment 15, wherein the stripping gas contains nitrogen, methane, flue gas, or combinations thereof. Embodiment 17 is the reaction unit of any of embodiments 14 to 16, wherein the regenerator further includes one or more cyclones adapted to separate flue gas from the catalyst.
Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/883,069 filed Aug. 5, 2019, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/057226 | 7/30/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62883069 | Aug 2019 | US |
