Ethanol dehydration pathways in H-ZSM-5: Insights from temporal analysis of products

Ethanol dehydration to ethene via direct and ether mediated paths is mechanistically investigated via transient experiments in a Temporal analysis of products, TAP-3E reactor over a temperature range of 473-573 K in Knudsen regime conditions. Pulse experiments of ethanol over H-ZSM-5 do not yield diethyl ether as a gas phase product. Cofeed experiments with diethyl ether and C-13 labeled ethanol show that ethene formation from diethyl ether is the preferential route. Kinetic parameters from ab initio based microkinetic modelling of ethanol dehydration are compared to the experimental data of the TAP reactor by an in-house developed reactor model code TAPFIT. Rate coefficients in ethene adsorption are in agreement with the ab initio based microkinetic modelling parameters. The experimental data from a diethyl ether feed are compared to the simulated responses from the ab initio based kinetic parameters and further optimized by regression analysis. Reaction path analysis with the optimized kinetic parameters identifies the preference of an ether mediated path under the applied transient experimental conditions.