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

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.