不同温度焙烧的Au-Pd/SiO2催化剂上甲醇选择性氧化制备甲酸甲酯

以溶胶固定法制备了Au-Pd/SiO₂催化剂,考察了催化剂焙烧温度对甲醇选择氧化制甲酸甲酯反应性能的影响。在200~500℃,400℃焙烧的Au-Pd/SiO₂具有最好的低温催化性能,在室温下就有活性,反应温度为100℃时甲醇转化率为25.3%,甲酸甲酯的选择性为100%。采用BET、XRD、UV-vis DRS、XPS、TEM和DRIFTS技术对催化剂进行表征,结果表明,催化剂中活性组分Au和Pd的高分散性,合适的Au和Pd粒径,Au-Pd合金的形成以及Au和Pd之间的强相互作用力,有利于甲醇氧化为甲酸甲酯反应的进行。初步推测出了甲醇在Au-Pd/SiO₂上氧化为甲酸甲酯的反应机理,甲醇在Au-Pd/SiO₂催化剂上是通过甲氧基中间体得到甲酸甲酯的。

Methanol selective oxidation to methyl formate on Au-Pd/SiO2 catalysts with different calcination temperatures

Au-Pd/SiO2 catalysts with different calcination temperatures were prepared by sol-immobilization method;their catalytic performance in oxidation of methanol to methyl formate was investigated.Among 200～500 ℃,Au-Pd/SiO2 catalyst calcined at 400 ℃ exhibits the best catalytic activity in the topic reaction at room temperature,and 25.3% methanol conversion with 100% selectivity to methyl formate can be achieved at100 ℃.They were characterized by BET,XRD,UV-vis DRS,XPS,TEM and DRIFTS.Good dispersity of Au and Pd,proper particle size of Au and Pd,the formation of Au-Pd bimetallic nanoparticles,and strong interaction between Au and Pd in the Au-Pd/SiO2 catalyst are beneficial to the oxidation of methanol to methyl formate.Furthermore,a preliminary reaction mechanism of methanol oxidation to methyl formate on the Au-Pd/SiO2 catalyst is inferred and methyl formate is gained from intermediate species methoxy in this reaction mechanism.