Study on preparation and characteristics of supported molybdophosphoric acid

The catalyst of molybdophosphoric acid supported on acid activated palygorskite was prepared via adsorption through reflux and evaporation.It was characterized by FTIR,XRD spectroscopy,SEM as well as thermogravimetry.Then,the synthesis of trioctyl citrate by citric acid together with n-butanol as reaction mass was used to test its activity.Several factors including the amount of catalyst,the ratio of acid to alcohol and reaction times were discussed by means of single factor and orthogonal experimental design,to get the optimal condition.The results show that the yield could reach 85.1% under the best condition: the amount of citric acid is 0.05 mol and the moral ratio of n(citric acid) ∶n(n-butanol) is 1 ∶4,reaction time is 2.5 h,mass of the catalyst is 1.5 g and reaction temperature is 145 ℃.The recycling tests show that the catalyst can be easily separated from the reaction systems and be reused for several times.