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以4A-分子筛为载体,Dawson结构磷钨酸钇(Y_2P_2W_(18)O_(62)·nH_2O)为活性组分,采用浸渍法制备出负载型40%Y_2P_2W_(18)O_(62)·nH_2O/4A-分子筛,并通过FT IR、EDS、SEM、NH3-TPD及N2吸附-脱附等方法对催化剂进行表征。将其用于催化水杨酸和乙酸酐反应制备乙酰水杨酸,考察了各因素对反应的影响。结果表明,负载前后磷钨酸钇均保持Dawson结构,Y_2P_2W_(18)O_(62)·nH_2O和40%Y_2P_2W_(18)O_(62)·nH_2O/4A-分子筛均呈球形,负载后催化剂的比表面积增大,酸强度和酸量均明显提高。在优化反应条件(水杨酸与乙酸酐摩尔比为1∶3,反应时间为30min,催化剂用量为反应物质量分数的2.3%)下,乙酰水杨酸收率为95.2%。催化剂重复使用6次,乙酰水杨酸收率仍保持为77.9%。
Dawson structure yttrium phosphotungstate (Y_2P_2W_ (18) O_ (62) · nH_2O) was used as the active component, and the supported 40% Y_2P_2W_ (18) O_ (62) · nH_2O / 4A-zeolite. The catalysts were characterized by FT IR, EDS, SEM, NH3-TPD and N2 adsorption-desorption. It was used to catalyze the reaction of salicylic acid and acetic anhydride to prepare acetylsalicylic acid. The effects of various factors on the reaction were investigated. The results show that both Dawson structure and Y_2P_2W_ (18) O_ (62) · nH_2O and 40% Y_2P_2W_ (18) O_ (62) · nH_2O / 4A-zeolites are spherical before and after loading, and the ratio of supported catalyst Surface area increased, acid strength and acidity were significantly improved. The yield of acetylsalicylic acid was 95.2% under the optimal reaction conditions (the molar ratio of salicylic acid to acetic anhydride was 1: 3, the reaction time was 30 min, the amount of catalyst was 2.3% of the mass fraction of reactants). The catalyst was reused six times and the yield of acetylsalicylic acid remained at 77.9%.