CuO-ZnO-Al_2O_3催化剂上的CO_2加氢反应——Ⅰ.表面吸附中间态的表征及反应机理的研究  

HYDROGENATION OF CO_2 ON CuO-ZnO-Al_2O_3 CATALYSTS Ⅰ. CHARACTERIZATION OF REACTION INTERMEDIATES AND REACTION MECHANISM

作　　者：陈林枫 黄开辉[1] 

机构地区：[1]厦门大学化学系物理化学研究所

出　　处：《Chinese Journal of Catalysis》1989年第1期1-1,共1页催化学报（英文）

摘　　要：用TPD-MS,XPS,ESR,脉冲反应技术和活性测定等研究了CuO-ZnO-Al_2O_3催化剂上CO_2的加氢行为。结果表明,CO_2加氢的反应动力学行为与CO加氢有明显不同,反应产物只有CH_3OH和CO,完全没有烃类产生,也没有出现结炭失活现象。反应时,CO_2先与OH作用生成HCO_3和CO_3,再进一步加氢生成HCOO和HCO等中间物种。HCOO有多种吸附状态,只有一部份HCOO能进一步加氢,而HCO则很容易加氢生成CH_3OH。还原过程中,各中间物种的吸附位不尽相同,进一步反应需要的H的状态可能也不同。CO_2,CO和CH_3OH可能通过中间物种HCOO相互转化。催化剂的活性和选择性与Cu(Ⅰ)和Zn(Ⅰ)的数量密切相关。The reaction mechanism of CO2 hydrogenation on CuO-ZnO-Al2O3 catalysts was studied with TPD-MS, XPS, ESR, pulse reaction technique and activity measurement. The results showed that the product distribution of CO hydrogenation was greatly different from that of CO2 hydrogenation in which there were only two products, CH3OH and CO,and no alkanes or alkenes and metal carbides were detected . CO2 preferentially reacted with OH to form HCO3 and CO3. Then HCO3 or CO3 underwent hydrogenation to yield reaction intermediates such as HCOO and HCO . There were several different adsorption states of HCOO, only some of which could be converted into CH3OH or CO, most of which were inert, HCOO adsorbed strongly and occupied the sites for hydrogen adsorption and the sites for decomposition of HCOO, thus hindering the reaction. On the contrary, HCO was quite easily hydrogenized to produce CH3OH. HCOO and HCO adsorbed at different sites and required different adsorption states of adsorbed hydrogen for hydrogenation,probably H- at ion site of metal oxide for HCOO and H6~ (0<6<1) at atom site of metallic Cu for HCO. Adsorbed hydrogen also played an important role determining the product selectivity. Lack of H led to the decomposition of HCOO to CO, CH3OH, CO, and CO may be converted into each other through ths intermediate HCOO, The formation of methanol is relevant to Cu ( I ) and Zn (I ).

关 键 词：CO2加氢反应 CUO-ZNO AL2O3催化剂 

分 类 号：O643.32[理学—物理化学]