Study On The Alkylation Of Toluene With High-Siliceous Mordenite Catalyst Using Ion-Exchanged Modification

O-xylene (OX) OX and P-xylene (PX) are important raw materials in chemical industry. The methylation of toluene with methanol has obvious superiority to the traditional disproportional of toluene for the production of OX and M-xylene (MX). With the aim of improving the catalytic performance, conversion and selectivity, of siliceous mordenite for the methylation of toluene with methanol, the present work investigated the catalytic performance of the various ions exchanged mordenite for the methylation of toluene with methanol. The NH3-TPD, XRD, Py-IR, IGA, ICP-AES, SEM and N2 adsorption and desorption were employed to characterize the structure and surface properties of the zeolite for the understanding of the catalytic performance.The siliceous mordenite with different Na/H exchange degree, which were exchanged in ammonium nitrate solutions, were used for the toluene methylation reaction. It was found that the production xylene mixture contains 38-46% OX, which is higher than its in the equilibrium xylene mixture. The OX selectivity decreases at first and then increases, while the conversion of toluene increases at first and then decreases when the Na/H exchange degree rises. The moderate exchange degree of 70%-85% is proper for the methylation of toluene with methanol.The HKMOR and HLaMOR samples, which were ion-exchanged with K+ and La3+ by wet method, were used for the toluene methylation reaction. It is found that the amount of OX is about 40% in the xylene mixture. Compared to the HNaMOR samples, the HKMOR samples could inhibit the by-reactions and the HLaMOR samples could improve the conversation of toluene (5%) for the toluene methylation.