International Journal of Hydrogen Energy, Vol.42, No.34, 21762-21774, 2017
Tailored Ce- and Zr-doped Ni/hydrotalcite materials for superior sorption-enhanced steam methane reforming
Multi-functional hybrid materials are attractive for producing high-purity hydrogen (H-2) via catalytic steam reforming coupled with low temperature adsorptive separation of CO2. In this work, modified Ni/hydrotalcite-like (HT1c) hybrid materials promoted with Ce and Zr species were synthesized and applied for the sorption-enhanced steam methane reforming process (or SESMR). The promotion with Ce and Zr resulted in strongly basic sites for CO2 adsorption, and hence, improved H-2 production. Especially, the Ce-promoted hybrid material (Ce-HM1) exhibited the highest adsorption capacity (1.41 mol CO2/kg sorbent), producing 97.1 mol% H-2 at T = 723 K, P = 0.1 MPa, S/C = 4.5 mol/mol and gas hourly space velocity or GHSV = 3600 mL/(g h); the breakthrough time was 1 h. High surface area and basicity of the promoted materials inhibited coke formation and undesired reactions. In addition to the improved catalytic activity and adsorption characteristics, these materials were stable and easily regenerable. Multi-cycle durability tests revealed that both the promoted materials Ce-HM1 and Zr-HM1 remained stable for up to 13 and 17 cycles. In contrast, the unpromoted hybrid material (HM1) was stable for 9 cycles only. Thus, promotion with Ce and Zr was beneficial for producing pure H-2. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.