Hydrothermal synthesis of nanocrystalline H[Fe, Al]ZSM-5 zeolites for conversion of methanol to gasoline

Nanocrystalline H[Fe, Al]ZSM-5 zeolites with different Fe content were synthesized by hydrothermal method with tetrapropylammonium hydroxide (TPAOH) as structure-directing agent (SDA), in which tetraethyl orthosilicate (TEOS) and sodium aluminate (NaAlO2) were used as Si and Al sources, respectively. The prepared samples were characterized by means of techniques such as XRD, SEM, N2 adsorption–desorption, ICP-AES, UV–Vis, NH3-TPD, pyridine-FTIR and FT-IR. The results indicated that Fe species could be incorporated into ZSM-5 zeolite framework in the forms of isolated Fe3+ and small oligomeric FexOy clusters, resulting in the formation of some new active sites and the lower Brønsted acid sites content. The catalytic performances of prepared nanocrystalline H[Fe, Al]ZSM-5 zeolites were evaluated by methanol to gasoline (MTG) reaction in a fixed bed stainless-steel reactor. The catalytic results illustrated that the incorporation of Fe enhanced the activity and stability of nanocrystalline H[Fe, Al]ZSM-5 catalysts in MTG reaction and reduced the yield of aromatics in gasoline. The methanol conversion was higher than 99% for about 110 h by optimizing the Fe content, meanwhile, the gasoline yield reached up to 32.7%, the aromatics and durene selectivity were controlled to a low level of 38.7% and 0.47%, respectively.