Study on catalysts for higher hydrocarbon and aromatics formation from small alkane molecules

In this研究项目，我们已经尝试开发新的catalysts，which can covert small alkane molecules such as methaneethane and propane into higher hydrocarbons or aromatic compounds. First of all，我们已经投资了关于silica supported group VIII metal catalysts using CH D24关于D2-CO的反应封闭gas circulation system并发现benzene是形式选择amhydrocarbons . Dependence of the initial rates ofCH - D24 -CO reactions as well as CH - D24 - D2 coupling and CO disproportionation upon the particlesizes of Rh was investigated by changing the loading amount of Rh on silica. the TOFs for benzeneformation in CH - co reaction and C - D22 - D2 formation in CH - D24 - D2 coupling were increasedabruptly by decreasing the loading amount of Rh. On the contrary，the TOF of CO i D22 D2 formation by CO disproportionation was decreased by decreasing the loading.These results suggest that smaller Rh particle may增强the dissociation of methane C-H bond tosupply surface hydrogen for benzene formation.我们也有投资the addition效应ofrear-earth oxides to Rh/SiO D22 D2 catalysts，and found that Nd - D22 - D2O - D23 - D2 is the effective additives for benzene acceleration for morethan ten time . on the other hand，我们已经建立了conventional flow reactor system and studied the methane coupling reaction overmolybdenum carbides as as supported group VIII metal catalysts. In the case of Mo D22 D2Ccatalysts,benzene可以formed with the 10-20% conversions and about 60% selectivity In the cases of silicasupported Co, Ni, Ru, Pd, Os, Ir and Pt catalysts，small amount of benzene was detected over Rh/SiO D22 D2，Ir/SiO D22 - D2 and Pt/SiO D22 - D2 catalysts. However，the deactivation of the catalytic activity was so severe in any catalysts maybe because of thecarbon accumulation. Further improvement of the catalytic systems are required for practical use ofthese catalysts。

In this research project, we have tried to develop new catalysts, which can covert small alkane molecules such as methane, ethane and propane into higher hydrocarbons or aromatic compounds. First of all, we have investigated CHィイD24ィエD2-CO reaction over silica supported group VIII metal catalysts using closed gas circulation system, and found that benzene is formed selectively among hydrocarbons. Dependence of the initial rates of CHィイD24ィエD2-CO reactions as well as CHィイD24ィエD2 coupling and CO disproportionation upon the particle sizes of Rh was investigated by changing the loading amount of Rh on silica. The TOFs for benzene formation in CHィイD24ィエD2-CO reaction and CィイD22ィエD2 formation in CHィイD24ィエD2 coupling were increased abruptly by decreasing the loading amount of Rh. On the contrary, the TOF of COィイD22ィエD2 formation by CO disproportionation was decreased by decreasing the loading. These results suggest that smaller Rh particle may enhance the dissociation of methane C-H bond to supply surface hydrogen for benzene formation. We have also investigated the addition effect of rear-earth oxides to Rh/SiOィイD22ィエD2 catalysts, and found that NdィイD22ィエD2OィイD23ィエD2 is the effective additives for benzene acceleration for more than ten times.On the other hand, we have constructed conventional flow reactor system and studied the methane coupling reaction over molybdenum carbides as well as supported group VIII metal catalysts. In the case of MoィイD22ィエD2C catalysts, benzene can be formed with the 10-20% conversions and about 60% selectivity. In the cases of silica supported Co, Ni, Ru, Pd, Os, Ir and Pt catalysts, small amount of benzene was detected over Rh/SiOィイD22ィエD2, Ir/SiOィイD22ィエD2 and Pt/SiOィイD22ィエD2 catalysts. However, the deactivation of the catalytic activity was so severe in any catalysts maybe because of the carbon accumulation. Further improvement of the catalytic systems are required for practical use of these catalysts.