负载型铼催化剂体系与甲醇选择氧化性能的关系  

Correlation of Performance and Structure of Supported Rhenium Catalysts for Methanol Selective Oxidation

作　　者：袁友珠[1] 曹为[1] 蔡启瑞[1] 岩泽康裕[2] 

机构地区：[1]厦门大学化学系物理化学研究所固体表面物理化学国家重点实验室,厦门361005 [2]东京大学化学系

出　　处：《高等学校化学学报》2002年第5期902-905,共4页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:29873037和20023001); 教育部优秀青年教师基金; 高等学校骨干教师计划课题资助。

摘　　要：以铼酸铵为前驱体，制备了氧化物负载型铼催化剂并研究其甲醇选择氧化反应的催化性能．结果表明，Fe2O3和V2O5 等氧化物负载型铼催化剂表现出很高的甲醇选择氧化制备二甲氧基甲烷的催化性能，选择性可达 90％～94％（摩尔分数）．选择氧化反应活性与铼担载量有关．在α－Fe2O3担载的铼催化剂中，以担载质量分数为 1％～3％铼的催化剂活性最高［450 mmol／（h·g Re）]，而高于 3％的铼担载量，单位铼催化活性逐渐下降．XRD，XPS和脉冲反应等结果表明，铼酸铰负载于α-Fe2O3 载体上，并于He气氛中焙烧后，所得表面铼物种与担载量有关，当低于单层担载量时以 Re6+占主导，而高于单层担载量时则 Re6+与 Re4+物种共存．Abstract Supported Re catalysts were prepared by impregnation of ammonium perrhenate precursor on oxide supports, followed by calcination at 673 K in He steam. Iron-oxides and V2O5 supported Re catalysts showed a higher activity and selectivity for the catalytic methanol oxidation to dimethoxymethane [3CH3OH + (1/2)O2 CH2(OCH3)2 + 2H2O]. The selectivity was as high as 90%?4% (molar fraction) at 513 K. The highest reaction rate of 450 mmol ?h-1 ?g-1 Re on -Fe2O3 supported Re catalysts was achieved with the Re loading weight of 2%(mass fraction). The reaction rate gradually decreased with the increase of Re loading weight. Calcination of ammonium perrhenate alone at 673 K in He gave mono-clinic ReO2 as a main product. However, the application of the iron-oxide may prevent Re7+ from reducting to Re4+ during the calcination at 673 K in He in the case of proper Re loading weight probably through the interaction of ammonium perrhenate with the supports, leading to the growth of Re6+ on the catalyst surface. Above the monolayer loading weight of ReO3, there was coexistence of Re6+ and Re4+ on the catalyst surface. A redox mechanism between Re6+ and Re4+ species on the catalyst surface was proposed to be responsible for the high performance in the methanol selective oxidation to dimethoxymethane.

关 键 词：负载型 铼催化剂 甲醇 选择氧化 二甲氧基甲烷 催化性能 

分 类 号：O623.11[理学—有机化学] O643.361[理学—化学]