Biofuels & Bioenergy

Biography

Biography: Timur Dogu

Abstract

Dimethyl Ether (DME) is a highly promising non-petroleum green diesel fuel alternate. As compared to conventional compression engine fuels, much lower CO, NOx and particulate matter emissions were reported from DME powered engines. Conventionally, DME is produced by dehydration of methanol over solid acid catalysts [1]. However, recent developments have shown that DME could directly be synthesized from synthesis gas, which can be obtained from biogas through a dry reforming process or by steam reforming of biomass [2,3]. Direct synthesis of DME involves methanol synthesis and dehydration reactions at the same proximity within the reactor and hence requires new bi-functional catalysts with high DME selectivity. In the present study, direct synthesis of DME was investigated using bi-functional catalyst pairs, which were composed of Cu based methanol synthesis catalysts and mesoporous alumina supported silicotungstic acid. Effects of catalyst combinations, CO/CO2 ratio of the feed stream and temperature on DME yield were investigated. High acidity of silicotungstic acid impregnated mesoporous alumina facilitated in-situ dehydration process, giving very high DME yields. Experimental results obtained with different CO2/CO ratios in feed stream proved the positive effect of CO2 on both overall conversion of CO+CO2 and DME yield. Highest DME selectivity values, approaching to 90%, were achieved with a feed stream composition of CO/CO2/H2=40/10/50, at 275 oC. Further increase of CO2/CO ratio in the feed stream facilitated the occurrence of reverse water gas shift reaction, which caused formation of higher amouts of water and hence a negative effect on the dehydration of produced methanol.Results obtained in this work were highly promising for the synthesis of DME directly from syngas which can be obtained from biogas through a dry reforming process.