(736d) Techno-Economic Evaluation of H2 Production Using Chemical Looping Dry Reforming | AIChE

(736d) Techno-Economic Evaluation of H2 Production Using Chemical Looping Dry Reforming


Mantripragada, H. - Presenter, University of Pittsburgh
Veser, G., University of Pittsburgh
Chemical looping dry reforming (CLDR) is a novel process for production of inherently separated syngas (H2 and CO) streams. In CLDR, CH4 is first converted to a pure hydrogen stream and solid carbon via thermocatalytic cracking over a metal catalyst in a “cracker” reactor. The deposited carbon is then selectively removed in an oxidizer reactor using CO2 as oxidant, resulting in the production of high-purity CO and regenerating the metal which is recycled back to the cracker reactor. The metal thus acts as a “carbon carrier” as opposed to an “oxygen carrier” as in typical chemical looping processes. Overall, CLDR results in the formation of inherently separated syngas streams, while at the same time addressing some of the key shortcomings of conventional methane cracking, such as low CH4 conversion, rapid catalyst deactivation, and large temperature excursions during carbon burn-off in the oxidation half cycle.

In the present study, we perform a techno-economic evaluation of a CLDR process that is designed to maximize H2 production by combining CLDR with water gas shift (WGS) in order to utilize the produced CO for further H2 production. Different configurations are evaluated for supplying the heat required for the endothermic dry reforming reaction via combustion of additional CH4 or combustion of a fraction of the carbon produced in the cracker reactor using either pure oxygen or air. All configurations include CO2 capture and H2 purification via pressure swing adsorption. Building on our previous fixed-bed experimental results, reactor-level mass and energy balance calculations are performed and coupled with a systems-level model that incorporates thermodynamic calculations of individual process components such as water gas shift reactors, blowers, feed compressors, CO2 capture, PSA, and heat recovery equipment as well as steam turbines. Capital cost models for the major equipment and operating costs (catalysts, chemicals, fuel etc.) are also developed using data in the open literature. The results from the performance model are combined with the cost models to comparatively evaluate the three configurations based on performance and cost metrics such as energy efficiency, chemical efficiency, CO2 emissions, capital costs, and cost of H2 production. The results are compared with conventional H2 production pathways using steam reforming and dry reforming of methane. The results are used to identify areas where CLDR systems have technical and cost advantages over conventional processes and highlight factors which need improvement.