A Composite Zeolite Catalyst for One Step Estrification Synthesizing TOP Directly from H₃PO₄-IR and XPS Characterization of the Catalyst

The preparations of SnO₂-HL catalyst as well as its IR and XPS characterization results are for the first time being described in the present pater.This composite zeolite catalyst was applied to synthesizing trioctyl phosphate （TOP） directly from phosphoric acid with actanol and a positive result was obtained.According to the IR characterization,the ratio of L acid concertration to B acid concertration C^L/C^B rose with an increase in the Sn（IV） content of the catalyst,at the same time the yields of TOP rose from 34% to 88% as shown in tables 1 and 2.This result reveals that the L acid center plays an inportant role in the above reactions.A possible mechanism for this catalytic reaction is discussed in this paper.All characterization and analysis of these catalysts before and after use demonstrated that tin existed in Sn（IV） form and its valence didn’t change before or after use.It was found that the intensity of the correspondent Sn（IV） peaks on XPS spectra decreased as the ereactivity of these samples decreased,see Fig.2. It shows that more Sn（IV） content in catalyst is beneficial for its catalytic reactivity.This effect coincided with the IR characterization result and demonstrated that Sn（IV） is a main active component of the catalyst.The reason for decreasing reactivity mainly originated from the partial release of Sn（IV）.