Modification of the ZSM-5 zeolite using Ga and Zn impregnated silica fibre for the conversion ofn-butane into aromatic hydrocarbons

Abstract

The modification of ZSM-5 by metals is generally performed by methods such as ion-exchange, impregnation, chemical vapour deposition and physical mixing. In this work a silica fibre pre-impregnated with Ga and Zn has been used during the synthesis by which Ga-ZSM-5 and Zn-ZSM-5 zeolite catalysts were prepared. The synthesised zeolite catalysts were characterised by an X-ray powder diffractometer, a scanning electron microscope, an X-ray fluorescence spectrometer, a solid state NMR, an energy dispersive X-ray analyser and a sorptomatic 1900. The acidity of the catalysts was determined by temperature programmed desorption of ammonia. The reaction ofn-butane to aromatic hydrocarbons was carried out over the H-ZSM-5, Ga-ZSM-5 and Zn-ZSM-5 catalysts and it was observed that these catalysts exhibited high catalytic activity in the conversion ofn-butane and formation of aromatic hydrocarbons. The effect of temperature on the conversion ofn-butane and formation of aromatic hydrocarbons was studied at 713, 743, 773 and 803 K with a space velocity (WHSV) of 2.5 h−1. The effect of time on stream on then- butane conversion and formation of aromatic hydrocarbons over the synthesised catalysts was investigated at 803 K for 4.5 h.