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高比表面积介孔SiO2负载V-P氧化物催化乙酸-甲醛羟醛缩合制丙烯酸研究

Preparation of acrylic acid via aldol by condensation of vapor-phase acetic acid with formaldehyde over mesoporous SiO2 with high specific surface area supported V-P oxides

    摘要
  • 摘要: 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NH3-TPD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VPO/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%。

     

    Abstract: The VPO/SiO2-x (=6, 8, 10, 12, average pore size) catalysts are prepared by impregnation methods using high specific surface area SiO2 with different pore size as supports. The catalysts are characterized by BET, XRD, XPS and NH3-TPD, 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.

     

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