Mechanism investigation of key reactions during tar component reforming process
Density functional theory calculations were employed to investigate the mechanisms and energy changes involved in C-C bond cracking,CH4 reforming,and water gas shift reactions in the tar reforming process.The findings reveal that,in the C-C bond cracking reaction,C3H8 initially adsorbs onto the catalyst surface to form adsorbed C3H8*,subsequently undergoing cleavage to produce CH3*and CH2CH3*.While the cracking reaction is exothermic,it is hindered by a significant energy barrier and difficult to carry out.In the CH4 reforming reaction,CH4*undergoes sequential dehydrogenation reactions,producing CH3*,CH2*,and CH*.Comparatively,CH*has a greater tendency to react with OH* to form CHO*,which further undergoes dehydrogenation to form CO*.Additionally,H*generated in each step combines to form H2*.Throughout the CH4 reforming process,the rate-limiting step is the cracking of CH2*to CH*.In the water gas shift reaction,the OH*species formed from H2O*decomposition prefers to combine with CO*to generate COOH*rather than directly reacting with H*to produce H2*.COOH*removes H and generates COO*,which is the rate limiting step.
国家科技期刊平台
NSTL
万方数据
维普
