(406j) The Modeling and Validation of CO Preferential Oxidation (CO PROX) Multi-Reactor System Using CuO/Rare Earth-Doped Ceria Catalysts for Commercial Diesel Reforming Applications

Bae, J., Korea Advanced Institute of Science and Technology (KAIST)
The multi-reactor system using copper-ceria mixed metal oxide catalysts was proposed for the CO preferential oxidation (CO PROX) in H2-rich streams. Although the CO PROX reactor system using precious metal-based catalysts has been widely adopted in commercial applications, it has crucial drawbacks such as severe exothermic hydrogen oxidation, unwanted methanation and narrow operating temperature window due to its intrinsic reaction mechanism. To solve the problems, researchers have introduced the redundant inter-coolers and liquid coolant pumps between the CO PROX reactors to keep the operating temperature for each reactor, however the additional heat exchangers lead the over-sized system. In this study, we demonstrated the possibility of copper-ceria catalysts for CO PROX system as an alternative of current precious metal-based catalysts and we suggested optimized multi-reactor design to reduce physical size of the CO PROX system without redundant heat exchangers and coolers. Rare-earth elements doped cerium oxides synthesized using a glycine nitrate combustion method were prepared as a support material for the catalytic system. Various rare-earth elements such as La, Pr, Nd, Sm, Gd, and Tb were introduced in the ceria lattice and the final catalysts containing copper oxides were demonstrated to find its operating temperature for CO PROX reactions. Several characterizations of the prepared catalysts in terms of structural and redox properties using inductively coupled plasma atomic emission spectrometer (ICP-AES), N2-isotherms, X-ray diffraction (XRD), transmission electron microscope (TEM) and temperature programmed reduction (H2-TPR) analyses. The industrial CO PROX reactants simultaneously containing H2, CO, CO2 and H2O were blended to demonstrate the CO PROX activity and selectivity of the prepared catalysts. The introduction of rare-earth dopants in the ceria support showed significant effect on the CO PROX activity, selectivity and operating temperature. Consequently, we could utilize these various copper-rare earth doped ceria catalysts to construct the multi-reactor CO PROX system in proper temperature regions for each reactor. The computational fluid dynamics (CFD) modeling using commercial software was performed to build the complete multi-reactor CO PROX system with different copper-ceria catalysts for each reactor canister and laboratory scale validation was also conducted. Moreover, techno-economic evaluation was followed to compare the current precious metal-based CO PROX system with the newly proposed copper-ceria based system in the case of commercial diesel reforming application.