Development of a New Ternary Al₂O₃-HAP-Pd Catalyst for Diethyl Ether and Ethylene Production Using the Preferential...

This study aims to convert ethanol to higher value-added products, particularly diethyl ether and ethylene using the catalytic dehydration of ethanol. Hence, the gas-phase dehydration of ethanol over Al₂O₃-HAP catalysts as such and modified by addition of palladium (Pd) in a microreactor was evaluated. The commercial Al₂O₃-HAP catalyst was first prepared by the physical mixing method, and then, the optimal ratio of the Al₂O₃-HAP catalyst (2:8 by wt %) was impregnated with Pd to develop a new functional catalyst to alter surface acidity. Based on the results, the combination of Al₂O₃ and HAP catalysts generated significant quantities of weak acid sites which demonstrates an enhancement in catalytic activity. In addition, Pd modification in the optimal composition ratio of the Al₂O₃-HAP catalyst extremely increased the amount of weak acid sites as well as weak acid density due to the synergistic effect between the Pd and Al₂O₃-HAP catalyst that are supposed to suggest the active sites in the reaction. Among all catalysts, the Al20-HAP80-Pd catalyst displayed brilliant catalytic performance in the course of diethyl ether yield (ca. 51.0%) at a reaction temperature of 350 °C and ethylene yield (ca. 75.0%) at a reaction temperature of 400 °C having an outstanding stability under time-on-stream for 10 h. This is recognized to the combination of the effects of weak acid sites (Lewis acidity), small amount of strong acid sites, and structural characteristics of the catalytic materials used.