膨润土结构和组成对催化棉籽油酸二聚反应的影响

以棉籽油酸为反应原料,膨润土、碳酸锂分别为催化剂和助催化剂,在240℃下反应4 h,研究在棉籽油酸二聚反应中不同膨润土的结构和组成对其催化性能的影响.结果表明,不同膨润土的比表面积和孔隙度差别较大,但二者不是影响其催化性能的主要因素.而膨润土晶体的层间距和表面酸性对其产率影响较大,实验中二聚酸产率最大为70.26%,最小为43.58%,原因可能是较大的层间距可以提供较充足的反应空间,有利于体积较大的二聚产物分子的生成,亦有利于其从层状结构中扩散出来.另一方面,xL/xB的摩尔比值越大催化性能越好,原因可能是路易斯酸中心在不饱和脂肪酸的聚合反应中起到关键作用.三种膨润土xAl/xSi的摩尔比值在0.216~0.239之间,差别较小,其对反应的影响较小.

Effect of the structure and composite of bentonites on the dimerization of the cottonseed acid

Cottonseed oleic acid were taken as raw materials,?bentonite and lithium carbonate as the catalyst and cocatalyst, reaction at 240 ° C for 4 h .The influence of the structure and composite of different bentonites on the catalytic performance was investigated in the dimerization of the cottonseed oil acid. The results showed that the difference of the specific surface area and the porosity of different bentonites were comparatively large. But they were not the leading factor that influenced their catalytic properties. The layer spacing of the bentonite crystal and its surfacial acidity had an important effect on its yield. In the experiment, the maximum yield of the dimer acid is 70.26%, the minimum is 43.58%. The reason may be larger interlayer spacing can provide more adequate reaction space which is conducive to the generation of large volumes of dimeric molecules and help the product spread from the layered structure. In addition the catalytic properties was increased with the high molar ratio of the Lewis acid to the Br?nsted acid. The reason may be the L acid site plays a key role in the unsaturated fatty acid polymerization. The Al / Si molar ratio of three kinds of bentonite range from 0.216 to 0.239, so the difference is small. It has a small effect on the reaction.