Noble Metal based Catalysts for Natural Gas Steam Reforming Activity, Endurance and Kinetics

摘要: This thesis illustrates catalytic activity, stability and intrinsic kinetics of methane steam reforming (MSR) reaction over noble metal catalysts. The main objective this is to evaluate a best performing catalyst based on the maximization H2 production minimization CO in synthesis gas produced from MSR reaction. catalysts tested towards were Rh, Ru Pt supported different reducible irreducible oxides. oxides (CeO2, MgO Al2O3) used work synthesized their nitrite precursor by Simultaneous combustion (SCS) while Nb2O5 was prepared heat treatment Niobic acid obtained Companhia Brasileira de Metalurgia e Mineracao (CBMM, Brasil). In all metals deposited support wetness impregnation method, except Pt/CeO2 which one shoot SCS method. All calcined under calcination regimes. characterized techniques BET, chemisorption, porosiometery, XRD, XPS, ICP, TEM SEM analyses. Efforts have been made correlate activity with physical characterization. initially screened tubular fixed bed quartz reactor 4mm ID containing 30mg diluted 50mg inert. For screening test feed introduced at weight hourly space velocity 20 NLh-1g-1cat carbon ratio 3-4 depending upon catalyst. results basic analyzed terms conversion, dry reformate CO2 selectivity. Among only two chosen initial screening, Rh/CeO2 Pt/CeO2, for further concerning stability. determined daily start up shut down cycle (DSS) 6h performance period. total 150 h 100h DSS N2 environment 50h environment. 25 Additionally also continuous ageing. Both showed good during time As endurance reforming. firstly mass transfer limitations evaluated both experimentally theoretically. operated an integral mode no inert kinetic experiments. effect WHSV constant S/C 3 conversion product composition determined. partial pressures reactants varied varying steam-to-carbon feed. An attempt fit data using models available literature. perfect model proposed Berman, activation energy found be 38.6 kJ/mol