The aim of this thesis is to study the production of ethylene by dehydration of ethanol, which also leads to two main by-products: diethyl ether and acetaldehyde. This reaction represents a green way of obtaining this alkene since ethanol can be obtained from biomass. The reaction has been tested in a microreactor and products analysed with on-line gas chromatography, with three different catalysts – γ-alumina, H-Beta-38 and Sn-Beta-38, together with the uncatalysed reaction. Temperature and residence time effects have been studied. The catalysts were characterized with different physico-chemical techniques, in order to correlate their characterization results with catalytic properties of catalyst coated microplates in ethanol dehydration reaction. SEM-EDX, TEM, nitrogen physisorption, FTIR-Pyridine and white light confocal microscopy were used for the physico-chemical characterizations. An ultrasound pretreatment was performed to study the stability of catalyst coating on the microplates. Based on the ethanol dehydration experiments, H-Beta-38 catalyst coated microplate exhibited the highest production of ethylene. The fresh catalyst allowed complete conversion and 98 % selectivity towards ethylene, deactivating significantly after some hours. The kinetic model describing the distribution of the products for the reaction catalysed by H-Beta-38 was assessed, relating the formation of ethylene and diethyl ether to the concentration of Brønsted and Lewis acid sites, respectively. Experimental data were adequately described by the proposed mechanism. Limitations of this study are mainly related to the challenges of performing post-run analyses, because of a small amount of catalyst, and a need of the removing from the microplates. Moreover, the inlet flow of ethylene was not monitored, therefore an estimation of the inlet concentration was used.
|Publication status||Published - 2019|
|MoE publication type||G2 Master's thesis, polytechnic Master's thesis|