Synthesis of HTLcs modified by K3PO4 for side chain alkylation of toluene with methanol

A series of calcined HTLcs catalysts were prepared and modified with potassium phosphate by impregnation method to clarify the influence of catalyst alkalinity on the side chain alkylation of toluene with methanol for synthesis of ethylbenzene and styrene. The catalysts were characterized by X-ray diffraction (XRD), N2 physical adsorption–desorption, Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), NH3 temperature-programmed desorption (NH3-TPD) and CO2 temperature-programmed desorption （CO2-TPD）. It was found that the selectivity of styrene was highest (39.25%) when the K3PO4 loading was 7.5 wt%. And the total yield of styrene and ethylbenzene could reach 65.08% with 10 wt% K3PO4 loading. This might due to the fact that the addition of K3PO4 could adjust the acid and basic sites of catalysts. In addition, appropriate strength and amount of basic sites were favorable to producing more styrene.