Ni/SiO2催化剂上甲烷催化裂解制氢

研究了固定床反应器上甲烷在Ni/SiO2催化剂上的裂解反应，并分别用O2、H2O进行催化剂失活/活化循环实验，并对催化剂用XRD进行分析。结果表明,Ni/SiO2催化剂具有良好的催化性能,甲烷转化率～40%，并能在150 min的时间内保持其活性，无论是用空气氧化还是水蒸气汽化，都能有效地活化已失活的催化剂。XRD实验显示，多次裂解－再生循环过程，对催化剂结构没有明显破坏。

HYDROGEN PRODUCTION VIA DIRECT CRACKING OF METHANE OVER Ni/SiO2 CATALYSTS

The catalytic decomposition of methane as an alternative process for the production of hydrogen from natural gas has been studied. The results show that a 15% Ni/SiO2 catalyst has good activity for decomposition of methane to hydrogen and carbon deposit. The capacity of methane decomposition is 4.5 g CH4/g catalyst at reaction temperature range of 550 ℃～600 ℃. It means that the Ni/SiO2 catalyst is still active during deposition of several thousands carbon atoms on a Ni0 atom. It can be reasonably explained by the mechanism of carbon filament formation. The catalytic activity can be fully regenerated by either air oxidation or steam gasification and the catalyst is stable after 10 successive decomposition/regeneration cycles. XRD analyses indicate that no apparent increase in the amount of carbon remaining on the catalyst after successive regenerations and no structural changes in the nickel particles.