The calcium looping (CaL) process is a promising CO2 capture technology, which uses CaO-based sorbents by employing a reversible reaction between CaO and CO2, generally named as carbonation and cal...

Review on the development of sorbents for calcium looping

Effective integration of CO2 capture and its conversion is an attractive strategy to reduce the anthropogenic CO2 emissions meanwhile achieve the potential revenue of CO2 molecule. Calcium-looping dry reforming of methane (CaLDRM) has emerged as such a promising process, implemented over a bifunctional reactor combining a CaO-based sorbent and a Ni-based catalyst, to achieve CO2 capture and in-situ conversion with CH4 into syngas. Herein, we synthesize a bifunctional Ni-Ca based material, i.e. Ni and CeO2 nanoparticles co-loaded on ZrO2-coated CaCO3, which enables isothermal capture and release of CO2 at the temperature favorable for DRM reaction, allowing to operate CaLDRM process in a single reactor by simple gas switching. Thanks to the stabilization effect of the ZrO2 layer, both CaO and Ni particles are exempted from severe sintering, maintaining the activity of capture and catalysis. The addition of CeO2 contributes not only to combat the accumulation of inactive carbon during long-term DRM but also to activate CO2 and CH4, accordingly enhancing syngas production, during cyclic CaLDRM. Importantly, the bifunctional material can succesfully drive CaLDRM cycles, converting over 40 % of CH4 and CO2, under 5 vol% CO2 feed concentration (as low as real flue gas) at 720 °C, which is a thermodynamically extremely unfavorable condition (equilibrium conversion below 3 %).

Bifunctional Ni-Ca based material for integrated CO2 capture and conversion via calcium-looping dry reforming

Evaluation of CO2 sequestration capacity in complex-boundary-shape shale gas reservoirs using projection-based embedded discrete fracture model (pEDFM)

Sorption Enhanced Gasification (SEG) is being considered as a promising solid fuel conversion and carbon capture and sequestration technology since it can produce tailored syngas coupled with in-situ CO2 capture Over the years, considerable research has been conducted with high grade biomass in laboratory and pilot scale facilities targeting technical and process scale-up viabilities of the SEG process SEG has successfully been tested at semi industrial scale which demonstrates further scale-up potential (eg commercial demonstration plant) of this innovative technology The results showed that the operation window of SEG laid at a gasification temperature ranging from 600 °C to 750 °C By optimizing the process parameters, H2-rich syngas (>70 vol %db) and desired H2/CO ratios can be attained Also, the total tar content of the optimized process is reported to be low compared to those obtained from classical fluidized bed gasification processes So far, wood is mostly used as the feedstocks while tests with wastes including solid recovered fuels (SRFs) have also been conducted Cheap and readily available natural sorbents (such as limestone) enable a satisfactory operation, however, issues associated with attrition and deactivation still need to be addressed Accordingly, natural sorbents with improved properties, synthetic CaO-based sorbents as well as pre-treated natural sorbents are considered to overcome these limitations This paper therefore discusses the current status of the SEG technology with an emphasis on its industrial applications for flexible syngas production with in-situ CO2 reduction Moreover, challenges, process scale-up experiences and research gaps for the commercialization of this novel technology are identified in this review

Sorption enhanced gasification (SEG) of biomass for tailored syngas production with in-situ CO2 capture: Current status, process scale-up experiences and outlook

Various carbon dioxide (CO2) capture materials and processes have been developed in recent years. The absorption-based capturing process is the most significant among other processes, which is widely recognized because of its effectiveness. CO2 can be used as a feedstock for the production of valuable chemicals, which will assist in alleviating the issues caused by excessive CO2 levels in the atmosphere. However, the interaction of carbon dioxide with other substances is laborious because carbon dioxide is dynamically relatively stable. Therefore, there is a need to develop types of catalysts that can break the bond in CO2 and thus be used as feedstock to produce materials of economic value. Metal oxide-based processes that convert carbon dioxide into other compounds have recently attracted attention. Metal oxides play a pivotal role in CO2 hydrogenation, as they provide additional advantages, such as selectivity and energy efficiency. This review provides an overview of the types of metal oxides and their use for carbon dioxide adsorption and conversion applications, allowing researchers to take advantage of this information in order to develop new catalysts or methods for preparing catalysts to obtain materials of economic value.

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Seyed Mojtaba Hashemi

Papers

Solution combustion synthesis of zirconia-stabilized calcium oxide sorbents for CO2 capture