Ag/SiO2催化剂用于甲氧基丙醇氧化反应

Ag/SiO2 catalyst for the oxidative of methoxypropanol

摘要:

采用等体积浸渍法制备Ag/SiO2催化剂，基于XRD、SEM、TEM、O2-TPD表征和甲氧基丙醇（MOP）催化氧化反应测试，考察不同Ag负载量（以SiO2质量为基准的Ag质量百分数，下同）Ag/SiO2催化剂的催化性能，并对比15%Cu/SiO2（以SiO2质量为基准的Cu质量百分数为15%）和15%Ag/SiO2的微观形貌和催化性能差异。结果表明，15%Ag/SiO2催化剂具有较高的催化活性，在反应温度300 ℃、液时空速1.8 mL/(g·h)、体积空气流量80 mL/min的条件下，MOP转化率为95.05%，目标产物甲氧基丙酮的选择性为85.07%，可稳定运行72 h；15%Ag/SiO2在反应80 h后，积碳率达到13.5%；相比15%Cu/SiO2的Cu物种粒径（15.2 nm），15%Ag/SiO2具有更小的Ag物种粒径（3.1 nm），分散性更好；Ag的氧吸附类型和高度分散是MOP在Ag/SiO2催化剂上氧化的重要因素，Ag与SiO2载体的强相互作用和良好的抗积碳能力为催化剂的稳定性提供了有利条件。

Abstract:

The Ag/SiO2 catalyst was prepared using the equal volume impregnation method and its catalytic performance with varying Ag loads (percentage of Ag mass based on SiO2 mass) was investigated through XRD, SEM, TEM, O2-TPD characterization, and MOP catalytic oxidation reaction test. A comparison between the microscopic morphology and catalytic properties of 15% Cu/SiO2 and 15% Ag/SiO2 revealed that the latter had higher activity. At a reaction temperature of 300 ℃, liquid space velocity of 1.8 mL/(g·h), and volume air flow rate of 80 mL/min, the conversion rate for MOP reached 95.05%, while selectivity for methoxyacetone was at 85.07%. Stable operation for up to 72 hours was achieved; however, after an extended run time of up to 80 hours, carbon deposition rates reached as high as13.5%. Compared to Cu species particle size in the former (15.2 nm), Ag species particle size in the latter (3.1 nm) is smaller with better dispersion due to oxygen adsorption type interaction between Ag and SiO2 carrier which are important factors for oxidation reactions on this catalyst system along with good carbon resistance providing favorable conditions for stability.