Methanol to C2 and C4 fuels over (Nb/Al)-pillared clay catalysts

Abstract

Pillared interlayer clay (PILC) is a low cost material, which is characterized by a large specific surface area, high pore volume and surface acidity that make it effective in catalytic reactions. In this work, montmorillonite was pillared with Nb and Al by cation exchange and then the obtained clays were characterized by XRD, EDS-SEM, N₂ adsorption/desorption techniques. The acid sites were analyzed by FTIR after the adsorption of pyridine and by NH₃-TPD. These materials were studied for methanol conversion reactions into C₂ and C₄ fuels in the temperature range of 250–400 °C for 2 h. The selectivity to C₂ and C₄ fuels was directly related to the strength of acid sites and the temperature of the reaction. At low temperatures, C₄ fuel was the major product. The increase of the temperature favored DME formation. The best performance for DME was obtained with a V–Nb PILC catalyst at 400 °C. This is due to weak acid sites (Brønsted and Lewis) present in this catalyst, identified by FTIR, and with lower acidic density, as observed by NH₃-TPD.