There is presently a need for capturing CO2 from gaseous streams such as Flue gas from combustion, CO2 wastes from other sources and even directly CO2 from Air in order to limit human impact on Global CO2 levels and related global weather and climate changes.
Preferably the captured CO2 should be able to be converted to valuable components (fuels, chemicals, building materials, polymers) or stored permanently as in the various Carbon Capturing and sequestration schemes being studied today.
The existing technology to capture CO2 from gas streams is based on a wet scrubbing process by Gas-Liquid contacting which is mass transfer limited, making use of Amines. These amines are costly and suffer from issues related to corrosion, amine degradation and solvent losses. Above all the amines also have toxicity issues and can degrade to nitrosamines, which are carcinogenic. Resuming the present state of the art technology for the capturing of CO2 exhibits several serious challenges:
There is a need for a technology, which addresses these drawbacks in order to enable low cost CO2 capturing, conversion and/or sequestration.
Solid-Gas adsorption have been developed based on amines, but these exhibit similar issues as the liquid amine systems, whereby the cost, complexity and low stability of these systems will lead to excessive high costs.
Low cost alternative for amines are carbonate systems as reported by:
The most preferred carbonated are those supported on Carbon instead of inorganic supports, see: SOO CHOOL LEE ET AL: “CO2 absorption and regeneration of alkali metal-based solid sorbents”, CATALYSIS TODAY 111, 15 Dec. 2015 (2015-12-15), pages 385-390, XP025116763, DOI: 10.1016/j.cattod.2005.10.051. KRIJN P. DE JONG ET AL: “Carbon Nanofiber-Supported K2CO3 as an Efficient Low-Temperature Regenerable CO2 Sorbent for Post-Combustion Capture”, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 52, 14 Aug. 2013 (2013-08-14), pages 12812-12818, DOI: 10.1021/ie4017072.
Unfortunately Existing Carbon supports are often brittle and therefore have a limited life span, especially when they also need to be transported, such as in conveyor, solids flow, fluidized flow conditions, or dilute solids-gas transport conditions. See: WO 2016050944 (ANTECY B.V. [NL]) 7 Apr. 2016 (2016-04-07).
On the other hand there is a strong need to increase the number of adsorption/desorption cycles per day (N) in order to reduce the quantity of Sorbent required per CO2 to be adsorbed as this in fact will have a significant impact on the physical size of the Absorber and Desorber and therefore also the capital expenditure (CAPEX) costs.
To improve the performance of the overall process and to reduce the costs besides solid sorbent capacity, the sorbent kinetics (mass transfer and accessibility of the sorbent sites) and the integrity of the sorbent physical properties (flow ability, particle integrity, strength and attrition resistance) are of great importance.
Preferably free flowing particles are required to transport the sorbent within short cycles from hours to minutes and possibly even seconds from the absorber to the desorber stage.
The foregoing requirements are usually contradictory.
The present invention solves this problem by producing shaped particles for CO2 capturing combining a hybrid organic-inorganic sorbent comprising:
This combination addresses the requirements set in the foregoing.
The base case for the Sorbent development, are shaped particles produced with Active Carbon as particle and support impregnated with K2CO3. The physical properties of these particles are limited (strength) as the accessibility (kinetics) meaning that the number of cycles and hence performance will be limited. (See
The technology as developed is to make use of the high accessibility and strength of inorganic based catalysts as applied in Fluid Catalytic Cracking with the good sorbent performance of the systems as indicated by Krijn de Jong et al.
As base a High accessibility inorganic, e.g. Alumina binder sorbent particle is applied wherein K2CO3 impregnated Active Carbon particles are imbedded.
A Carbon coated catalysts (CCA) is formed, for instance by treating a High Accessibility Inorganic, e.g. Alumina binder sorbent system with an organic Potassium molecule (e.g. Potassium Acetate) under pyrolysis conditions.
Potassium loaded nano-cellulose fibers (CF-K2CO3) are imbedded in a High Accessibility Inorganic, e.g. Alumina binder sorbent system. The nano-cellulose can be partially of fully carbonized in-situ to form Carbon fibers.
Same as F2 whereby part or all of the role of binding is replaced by biomass (waste) based nano-cellulose and/or lignin.
A full Cellulose/Lignin based high accessibility strong particle with K2CO3. Which may be wholly or fully carbonized to improve the CO2 adsorption capacity and kinetics
The following are compositions, which are embodiments of this invention.
Active Carbon Impregnated with 10% and 25% K2CO3
Pure Cellulose and Lignin Impregnated with 10% K2CO3
The nano-cellulose and/or lignin can be partially of fully carbonized in-situ.
As described in WO 2016/087186.
The nano-cellulose can be partially or fully carbonized in-situ.
Dried Algae Impregnated with K2CO3
The Algae can be partially or fully carbonized in-situ.
Sorbent compositions comprising 20%, 50% and 80% of a binding (peptizable) Alumina incorporating 80%, 50% and 20% of the above compositions
These compositions are evaluated by the following performance tests:
The following describes the large effect of N (Number of cycles per day) on the Sorbent performance:
CO2 m3 produced: CO2 (m3)
Sorbent volume: S (m3)
CO2(m3)=S(m3)×SC×N
Sorbent−Reactor Volume−CO2(m3)/(SC×N)
As indicated above besides solid sorbent capacity, the sorbent kinetics (mass transfer and accessibility of the sorbent sites) and the integrity of the sorbent physical properties (flow ability, particle integrity, strength and attrition resistance) are of great importance.
Free flowing particles are required to transport the sorbent within short cycles (minutes, seconds) from the absorber to the desorber stage. The foregoing requirements are usually contradictory.
This invention is based on a combination of the chemistry of Inorganic Oxides and/or Carbonate systems such as the K2CO3 systems as investigated by Krijn de Jong et al (2013) on a Carbon based support.
Obviously the Carbon Nano Fibers (CNF) as mentioned by de Jong et al cannot be used as such because of the high costs (±10 Euro's/kg) and the difficulty to form into attrition resistant hard sorbent particles. One can foresee a similar problem with Lackner's (2016)“Shaggy” sorbents, which (Ref: https://www.insidescience.org/what's-white-shaggy-and-could-help-reduce-carbon-dioxide-80) are very susceptible to attrition and difficult to form into a flowing sorbent.
Christoph Gebald et al. (D1) discusses the synthesis of an organic amine grafted nano-fibrillated cellulose as adsorbent. So Cellulose is used as a carrier and binder, which will not be sufficiently attrition resistant. Furthermore our invention specifically avoids the amines and the complicated synthesis of grafting on cellulose, and uses simple low cost inorganic carbonates as the CO2 sorbent and hence is not disclosed by Gebald et al. Furthermore Gebald et al only use cellulose as binder and do not include a second inorganic binder system as disclosed in our invention.
Arnaud Demilecamps et al (D2) discusses a cellulose silica aerogel, which as they show has a very low density (0.1-0.3 g/cm3) which implies a very poor attrition resistance and also is not suitable for transport or handling as required in our invention. Shaped particles as claimed in our invention can be in the form of extrudates, beads, pellets and/or microspheres, whereby density is significantly higher (>0.5 g/cm3).
EP 2100972A1 (D3) discusses the dissolution of Cellulosic materials in ZnCl2, but does not disclose the application as a catalyst/sorbent component and does not disclose the use in combination with a second inorganic binder to produce attrition resistant shaped particles as disclosed in our invention.
Maria Ciobanu et al (D4) discusses the loading of Calcium Carbonate on Cellulose. For the application intended Calcium is not a suitable sorbent, as very high temperatures are required to release CO2. Furthermore this publication does not disclose the application as a catalyst/sorbent component and does not disclose the use in combination with a second inorganic binder to produce attrition resistant shaped particles.
Number | Date | Country | Kind |
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EP16158029.5 | Mar 2016 | EP | regional |
EP16202944.1 | Dec 2016 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/054121 | 2/23/2017 | WO | 00 |