Modification of acid on beta zeolite catalysts by ion-exchange method for ethanol dehydration to diethyl ether
<p class="Mabstract">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.<strong></strong></p>