CaTiO_(3)催化正戊醛羟醛自缩合反应性能

CaTiO_(3)catalyzed self-condensation of n-valeraldehyde

将酸碱活性位点丰富的钙钛矿氧化物用于催化正戊醛羟醛自缩合反应。采用XRD、SEM、NH_(3)-TPD、CO_(2)-TPD对催化剂进行了表征,优化了催化剂制备和反应条件,明晰了催化剂酸碱活性位点之间的作用关系。结果表明,采用溶胶-凝胶法,在分散剂聚乙二醇(PEG-1000)加入量为2.5%[以Ca(NO_(3))_(2)·4H_(2)O质量为基准,下同]、500℃焙烧1h条件下,可以得到纯相CaTiO_(3),此时其分散性和催化性能较优。CaTiO_(3)催化正戊醛羟醛自缩合反应的适宜反应条件为:反应温度190℃,反应时间8 h,催化剂加入量15%(以正戊醛质量为基准,下同)。在该反应条件下,正戊醛转化率可达97.0%,产物2-丙基-2-庚烯醛的选择性可达99.1%。CaTiO_(3)催化剂使用4次后,其催化活性无明显下降。酸碱活性位点之间存在明显的协同催化作用。

Perovskite oxides with abundant acid-base active sites were ussed to catalyze n-valeraldehyde self-condensation.The catalysts were characterized by XRD,SEM,NH_(2)-TPD and CO_(2)-TPD,along with optimization on the preparation and reaction conditions as well as examination on the interaction between acid and base active sites.The results showed that pure phase CaTiO_(3)with better dispersion and catalytic performance was obtained by sol-gel method when calcined at 500℃for 1 h with dosage of dispersant polyethylene glycol(PEG-1000)=2.5%[based on the mass of Ca(NO_(3))_(2)•4H_(2)O,the same below].Moreover,under the optimal self-condensation conditions of reaction temperature 190℃,reaction time 8 h and catalyst 15%(based on the mass of n-valeraldehyde,the same below),the conversion of n-valeraldehyde and the selectivity of 2-propyl-2-heptenal reached 97.0%and 99.1%,respectively.Meanwhile,the catalytic performance of CaTiO_(3)showed no significant decrease after being recycled four times.There was an obvious synergistic catalysis between acid and base active sites.