Effect of Ni precursor salts on Ni-mayenite catalysts for steam methane reforming and on Ni-CaO-mayenite materials for sorption enhanced steam methane reforming

In view of climate change containment, sorption enhanced steam methane reforming (SESMR) appears as an interesting production route for H-2 with the additional advantage of CO2 capture application performed by high-temperature solid sorbents. CaO is largely employed as CO2 sorbent because of its low-cost mineralized forms (limestone and dolomite), of its high sorption capacity in the high temperature range compatible with steam methane reforming (SMR). Many recent studies have proposed purposely synthesized Ni-based reforming catalysts, used with high-temperature CO2 solid sorbents, or combined sorbent-catalyst materials (CSCM). For this last purpose, we studied the effect of Ni salt precursor (Ni nitrate hexahydrate or Ni acetate tetrahydrate) on properties and reactivity of Ni-mayenite catalysts or Ni-CaO-mayenite CSCM, synthesized by an already validated sequence of wet mixing (for sorbents synthesis) and wet impregnation (for catalysts and CSCM synthesis) methods. Although Ni acetate tetrahydrate was often reported as the best choice to improve textural properties, our study identified Ni nitrate hexahydrate as a definitely more suitable precursor than Ni acetate tetrahydrate in the purpose of developing efficient materials for SESMR. The dissimilar behaviors observed in reforming reactivity are related and explained by the differences in textural properties, Ni species dispersion, and reducibility. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.