疏水性固体酸H_3PW_(12)O_(40)/HZSM-5催化合成丙烯酸正丁酯

Preparation of butyl acrylate catalyzed by a hydrophobic solid acid catalyst-H_3PW_(12)O_(40) supported on HZSM-5

制备了负载型疏水性固体酸催化剂H3PW12O40/HZSM-5,并将该疏水性固体酸催化剂用于丙烯酸(简称AA)与正丁醇的酯化反应中。结果表明,硅铝摩尔比为60的HZSM-5负载质量分数为40%的H3PW12O40,180℃干燥2 h,H3PW12O40/HZSM-5催化剂的活性最高,丙烯酸转化率可达96.44%。H3PW12O40/HZSM-5催化剂循环使用4次,丙烯酸的转化率仍保持在71.98%。采用XRD、FTIR以及原位红外对催化剂的结构和酸性进行了表征,测试结果均表明H3PW12O40较好的分散于HZSM-5的表面,在催化剂表面存在Lewis酸和Brφnsted酸,且其负载型疏水性固体酸H3PW12O40/HZSM-5的酸量、催化活性和疏水性能均高于单组分H3PW12O40。

A novel solid acid catalyst, H3PW12O40（HPW） supported on HZSM-5, has been prepared for use in the esterification of acrylic acid （AA） with n-butanol. The molar ratios of Si to Al in the support, HPW loading and calcination temperature were optimized. The activity of the catalyst was found to be maximized when a material with w（H3PW12O40）= 40% was calcined at 180 ℃ for 2 h, with the conversion of AA being 96.44%. After being reused 4 times, the measured conversion of AA was still over 70 %. The catalysts were characterized by FTIR and XRD and their acidity was measured by in situ FTIR. The results indicate that HPW was successfully supported on the HZSM-5 with a high degree of dispersion on the support surface. Bands at 1525 cm^- 1 and 1686 cm^-1, characteristic of acid sites, were observed in the in situ FTIR spectra of HPW/HZSM-5 after adsorption of ammonia, indicating that HPW/HZSM-5 has both Lewis acid sites and Brφnsted acid sites.