SYNTHESIS AND CATALYTIC APPLICATIONS OF NI-BASED CATALYSTS ENCAPSULATED IN MESOPOROUS MATERIALS

Abstract

SBA-15 and derivatives are employed to synthesize Ni catalysts using two strategies. First, SBA-15 is used to prepare Ni-phyllosilicate structure derived catalysts. Ample hydroxyls from phyllosilicate play crucial roles in WGS and CO2 methanation. Zr and Ce incorporation into SBA-15 framework can further suppress undesired side reaction during WGS. Additionally, Mg incorporation into Ni-phyllosilicate can create medium basic sites, improving low-temperature CO2 methanation activity. Second, mesoporous ceria is synthesized using SBA-15 as template. Compared to Ni supported on conventional ceria, Ni catalyst encapsulated in mesoporous ceria exhibits superior low-temperature methanation activity due to more interfacial sites and higher basicity correlated to oxygen vacancies. Incorporating zirconia into mesoporous ceria lattice further promotes oxygen vacancy creation, which are beneficial for water dissociation in WGS. Ultimately, this thesis reveals structural and electronic nature of active sites, unravels structure-activity relationship and provides insights into intermediate species and reaction mechanisms of WGS and CO2 methanation.