The VPO/SiO2-x(= 6,8,10,12,average pore size)catalysts are prepared by impregnation methods using high specific surface area SiO 2with different pore size as supports.The catalysts are characterized by BET, XRD, XPS and N H3-T PD, and also investigated by heterogeneous catalysis of aldol condensation of acetic acid with formaldehyde to produce acrylic acid. The results show that all catalysts have higher specific surface area(>180 m2/g)and well-developed mesoporous structure,but with average pore size of 6.5 nm,8.7 nm,10.6 nm and 13.0 nm, respectively.The acrylic acid selectivity over the prepared VPO/SiO2-x catalysts follow the order of VPO/SiO2-10 > VPO/SiO2-12 > VPO/SiO2-8 > VPO/SiO2-6. The catalytic conversion of formaldehyde over VPO/SiO2-10(average pore size is 10.6 nm)reaches 61.2% when the reaction temperature is 350 ℃,with acrylic acid selectivity and yield of 76.8% and 47.1% respectively.%以不同孔径的高比表面积介孔SiO2为载体,通过浸渍法制备VPO/SiO2-x(x=6、8、10、12,平均孔径)催化剂.采用BET、XRD、XPS 和N H3-T PD对催化剂进行表征,并考察了其对甲醛-乙酸多相催化制丙烯酸的催化性能.结果表明,不同孔径V PO/SiO2催化剂均具有较高的比表面积(>180 m2/g)和发达的介孔结构,其平均孔径分别为6.5 nm、8.7 nm、10.6 nm和13.0 nm;VPO/SiO2上丙烯酸的催化选择性由于受催化剂孔径的影响依次为VPO/SiO2-10> VPO/SiO2-12>VPO/SiO2-8>VPO/SiO2-6.反应温度为350 ℃时,孔径为10.6 nm 的VPO/SiO2上丙烯酸的选择性和收率分别达到76.8% 和47.1%,甲醛转化率为61.2%.
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