Ni-W/CYCTS4 catalysts for coking gas oil(CGO) hydrotreating were prepared by the isovolumic impregnation method using nickel-tungstate as active metals.The composite supports were composed of TiO2-SiO2 complex oxides and modified Y zeolites.The properties of the catalyst modified by citric acid in the impregnation solution and the catalytic performance of hydrotreating coking gas oil were examined.The physical and chemical properties of the catalysts were investigated with BET
FT-IR
XRD
UV-Vis DRS and TG-DSC.The results indicated that citric acid as complexing agent could increase the dispersion degree of active species in catalysts.At the same time
citric acid could change the state of active metals and promote the formation of single polytungstate species and highly active nickel species in octahedral sites.The hydrotreating performance of the Ni-W/CYCTS4 catalysts modified by citric acid for coking gas oil was remarkably promoted