A facile strategy for preparation of phosphorus modified HZSM-5 shape-selective catalysts and its performances in disproportionation of toluene

Abstract The phosphorous modified HZSM-5 catalysts were prepared by using phosphoric acid as the precursor with the addition of ethanol during the impregnation process and their shape-selective performances in the synthesis of p -xylene by disproportionation of toluene were investigated. An excellent para -selectivity along with a relatively high catalytic activity was achieved over the phosphorous modified HZSM-5 catalysts. The addition of ethanol during the impregnation process promotes the transition of phosphoric acid to phosphate, which accomplished the cover of the external acid sites and the reserve of the acid sites in the pores of HZSM-5 zeolite after phosphorous modification.