Study Of The Isomerization Of Propylene Oxide Over Solid Acid Catalyst

As the third largest derivative of propylene in petroleum refining and chemical products,propylene oxide has an extremely important industrial application.Due to its unstable epoxy three-membered ring,it can participate in many reactions,thus can produce a large number of important chemicals.In addition,propylene oxide can also be isomerized to propionaldehyde,acetone and propylene alcohol under the action of a catalyst.As the isomerization reaction basically did not produce waste,and atomic utilization is high,in line with the concept of green chemistry,so it is significant that using the isomerization reaction of propylene oxide to peoduct propionaldehyde,acetone,propylene alcohol.In order to investigate the activity of propylene oxide isomerization and the relationship between product distribution and the nature of the acidic site of the catalyst,AIPO-5 zeolite and heteroatom aluminophosphate molecular sieve MeAPO-5 were synthesized.The acidity of these molecular sieve catalysts was qualitatively and quantitatively analyzed by NH3-TPD and Py-IR,and the results were correlated with the results of their catalytic isomerization.It was found that the strong acid sites and the strong L sites Is conducive to the formation of propionaldehyde,but not conducive to the formation of propylene alcohol.And with the increase of the total acid amount of catalyst L,the selectivity of propylene alcohol gradually decreased.It has also been found that the more the B acid amount of the catalyst,the faster the activity of the catalyst is reduced.SAPO-5 molecular sieve synthesized by different conditions was used to evaluate the isomerization performance of propylene oxide.The results showed that addition of surfactant during the molecular sieve synthesis can increase its isomerization activity,and also found that SAPO-5 with regular shape Molecular sieve grains have higher isomerization activity for propylene oxide.Next,we measured the catalytic activity of aluminophosphate molecular sieves with different Ce doping concentrations and found that when Ce/P = 0.075,the initial conversion of the catalyst was the highest.At the same time,the supported aluminum phosphate molecular sieve catalyst was studied and the isomerization activity of A12(S04)3/AIPO-5 and W03/A1PO-5 catalysts was tested.The conversion of these two catalysts was found to be higher than that of A1PO-5.And the selectivity to propionaldehyde was improved.In particular,the initial propanal formation rate of A12(S04)3/A1PO-5 catalyst reached 14.36 kg·h-1 kgcat'1.