Direct synthesis of H type ZSM-5 in shaped form and catalytic properties in methanol-to-hydrocarbon reaction

HZSM-5 zeolites as catalysts are conventionally synthesized through three steps: (1) preparation of Na type zeolites; (2) ion exchange into NH 4 type; (3) calcination. In this work, binder-free HZSM-5 zeolites with SiO 2 /Al 2 O 3 ratios of 50–170 were directly synthesized in the shaped form. The acid properties and pore structures of the HZSM-5 samples were appreciably affected by the SiO 2 /Al 2 O 3 ratio. In addition, these HZSM-5 samples had well preserved micropore structure, and even exhibited superior properties to the conventional one in methanol to hydrocarbon reaction with about 13% higher yield of C 5+ hydrocarbons and 63% higher aromatic selectivity. The improved catalytic performance might be attributed to the shortened b-axis, more acid sites, stronger acidity and higher Bronsted to Lewis acid ratios. More importantly, this synthesis method not only greatly simplifies the synthesis process of shaped HZSM-5 zeolites, but also reduces pollution and production cost.