Modification of acid on beta zeolite catalysts by ion-exchange method for ethanol dehydration to diethyl ether

Abstract

The catalytic ethanol dehydration to diethyl ether (DEE) over the synthesized beta zeolite (BEA) with different acidity on catalysts having Na and mixed Na-H forms was studied. The Na form of BEA catalyst was synthesized via the hydrothermal process, including non-calcined (Na-BEA_N) and calcined (Na-BEA_C) catalysts. The Na-BEA_C catalyst was successively used in the synthesis of different mixed Na-H forms under the ion-exchange method using the ammonium nitrate solution at 70°C for 2 h/cycle. In the present study, two different cycles were chosen, including one cycle (M-BEA_1) and four cycles (M-BEA_4) to compare the amount of acidity on catalysts. The results indicated that the M-BEA_1 catalyst exhibited a large surface area and contained the highest moderate acid site, which strongly affected the optimal catalytic activity at low temperature (<250°C) with ethanol conversion of 74.6% and DEE yield of 27.3%. However, the increased number of ion-exchange cycles had not shown remarkable effects on catalytic activity due to low surface area and moderate acidity.