Abstract
The deactivation by coke of a HZSM-5 zeolite catalyst has been studied in the transformation of methanol into hydrocarbons by cofeeding butane (n-butane). This reaction is of interest as an energy-neutral integrated process that enhances the activity in the cracking reaction and upgrades the paraffins formed as byproducts. The process was carried out in a fixed-bed reactor under the following conditions: temperature, 550 degrees C; pressure, 1 bar; space time, 2.4 and 4.8 (g of catalyst) h (mol of CH(2))(-1); time on stream, 5 h; methanol/butane molar ratio, up to 16/1. The coke was characterized using several analytical techniques (TG-TPO, FTIR, Raman, and NMR spectroscopies), and the effects of cofeeding butane on the coke composition and structure were determined. The results in terms of coke content and composition, are explained in terms of the different pathways of methanol and butane transformation.