DME synthesis from synthesis gas on the admixed catalysts of Cu/ZnO/Al2O3 and ZSM-5

Abstract

Na-ZSM-5 and H-ZSM-5 catalysts with three different Si/Al ratios were prepared to investigate methanol dehydration and direct DME synthesis. The acid strength of ZSM-5 increased with a decrease in the Si/Al ratios and methanol dehydration rate was maximized on H-ZSM-5(30) with the highest acid strength. The direct DME synthesis was conducted on the admixed catalysts of Cu/ZnO/Al2O3 and ZSM-5. The optimized solid acid composition on the admixed catalysts with Na-ZSM-5 for maximizing CO conversion was lowered with a decrease in the Si/Al ratio. The experimental results show that the overall DME synthesis rate can be determined by the intrinsic methanol synthesis rate on the admixed catalysts with the compositions higher than the optimized one and the overall rate can be controlled by the methanol dehydration rate on the admixed catalysts with the composition lower than the optimized one. (C) 2004 Elsevier B.V. All rights reserved.