A series of Na-modified H-ZSM-5 catalysts, with Na content varying from 0 to 80 mol%, were prepared by an impregnation method, characterized by TPD of ammonia and FT-IR pyridine methods, and tested for the dehydration of crude methanol (i.e. pure/anhydrous methanol containing 20 mol% of H2O) in a fixed-bed micro-reactor under normal atmospheric pressure. Though the unmodified H-ZSM-5 catalyst was more active and stable in the presence of water than the commercial γ -Al2O3, the Na modified H-ZSM-5 catalysts showed the optimum activity (CMeOII > 80%) and 100% selectivity for DME in a wide range of temperatures: 230-340 °C. The catalysts were tested for the time-on-stream (TOS) and remained least sensitive towards water for a total reaction period of 65 h. The superior performance of Na-modified H-ZSM-5 catalyst is attributed mainly to the elimination of strong surface acid-sites by partial substitution of Na in H-ZSM-5, resulting in the prevention of coke and/or hydrocarbon formation.
Bibliographical noteFunding Information:
This research was performed for the Carbon Dioxide Reduction & Sequestration Center, one of 21st Century Frontier R&D Programs funded by the Ministry of Science and Technology of Korea. The fellowship for V. Vishwanathan is supported by the Brain Pool Programme of Korea Science and Engineering Foundation (KOSEF).
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology