Aromatization of Methanol over La/Zn/HZSM-5 Catalysts

Aromatization of methanol over co-impregnated La/Zn/HZSM-5 zeolite catalyst was studied. The selectivity of aromatics and BTX (benzene, toluene, and xylene) reached 64.0% and 56.6%, respectively, using La/Zn/HZSM-5 at 437 degrees C, 0.1 MPa and methanol WHSV (weight hourly space velocity) = 0.8 h(-1). Catalytic results showed that the La species was a very good promoter, increased selectivity of aromatics, and prolonged the catalyst lifetime on stream. The effects of the SiO2/Al2O3 ratio in zeolite, Zn and La loading, WHSV, reaction temperature, water content in the feed and H-2 pretreatment of catalysts on the catalytic performance were studied in detail. Characterizations of the catalysts by thermogravimetric analysis (TGA), NH3-TPD (temperature programmed desorption), SEM (scanning electron micrograph), N-2 adsorption-desorption, XRD (X-ray diffraction) and XRF (X-ray fluorescence), were carried out to understand the structure and discuss the aromatization performance of La/Zn/HZSM-5 zeolite catalyst.