Mini-channel-structured Adsorption Reactor with In-situ Heat Exchanger for Rapid CO2 Adsorption and Regeneration

The proposed technology addresses the unique challenge of CO2 capture from flue gas streams to meet DOE’s CO2 capture cost target with low capital cost and high energy efficiency. Flue gas CO2 capture remains uniquely challenging due to the prohibitively large adsorption bed sizes needed in comparison to current commercial processes. Further, in currently available adsorption approaches, significant limitations exist, such as low adsorbent particle loading, high pressure drops, particle attrition, and the huge engineering effort and resource needed for particle specific scale-up. Quick removal of heat of adsorption and quick supply of heat for desorption presents another tremendous challenge which can take days in conventional approaches. MoleculeWorks proposes a novel adsorptive heat exchanger (AHX) unit for low-cost, energy-efficient CO2 capture from flue gas. This approach allows high adsorbent loading in a design that facilitates rapid adsorption and desorption of flue gas CO2 while still maintaining low pressure drops. Rapid in-situ regeneration is realized by introducing thermal fluid in direct contact with the thin dense metal foil so that the adsorbent can be heated up and cooled in mere minutes regardless the adsorbent bed size. MoleculeWorks AHX employs a unique thin adsorptive heat exchanger plates (AHEP) that can be stacked together to form millimeter sized flow channels for gas and thermal fluid. The thin AHEP structure (~1mm) consists of adsorbent powder held sandwiched within MoleculeWorks’ proprietary thin microporous metal membrane (30-60µm thick) and a thin dense metal foil (50µm). The innovative design allows for the use of any adsorbent powder without complex particle- specific material processing. The thin microporous membrane holds the adsorbent fines within the AHEP, preventing attrition and loss, yet allowing CO2 to rapidly diffuse through during adsorption and regeneration. In Phase I, 20cm x 20cm AHEP elements utilizing commercially available zeolite powders will be prepared to build a multi-stage adsorption heat exchange (AHX) prototype. The AHX unit will be built by aid of computational fluid dynamics modelling and analysis and will be demonstrated for CO2 adsorption through rapid thermal (TSA) and pressure swing (PSA) mode. A broad range of conditions will be tested to develop the specification of operating conditions for this new type of device. Techno-economic analysis will be performed, including manufacturing cost models for the AHX module fabrication and basic process design of flue gas CO2 capture using AHX units. The proposed reactor technology will facilitate scale-up and commercialization of new adsorbent materials by addressing costly material and process engineering issues. The technology would help reduce CO2 and environmental emissions in the US and be readily applicable to other industrial adsorption processes.