Tshepo Duncan Dipheko

Title : Ethanol Dehydrogenation over Carbon Supported (K)(Co, Ni, Fe)MoS2-based Catalysts

Abstract:

Utilizing renewable resources to synthesize fuels and high-value chemicals is a pivotal step for the chemical industry, given the limited nature of global natural gas and petroleum reserves. Due to the economic viability of large quantities of ethanol, it has been used to synthesize a variety of value-added chemicals that complement existing markets for petrochemical products. This leads to a decrease in reliance on oil supply, which has direct economic and geopolitical implications. Herein, ethanol dehydrogenation was studied over mono-, bi- and trimetallic-carbon-supported (K)(Co, Ni, Fe)MoS₂ catalysts. Across all catalysts, ethyl acetate was synthesised at a high quantity. The effects of catalyst textural properties on catalytic activity were studied and found to be substantial. It is established that catalysts with a large proportion of microporous structure are more active in the production of liquid products than those with a probable mesoporous structure. Both the morphology of molybdenum disulfide crystallites and the catalytic activity in the synthesis of oxygenated hydrocarbons are affected by the support material. The average length and stacking number of MoS₂, as well as the dispersion, were calculated. In all the reactions tested, the turnover frequency (TOF) rose as the average length increased and the dispersion decreased. The conversion of ethanol is expected to proceed on MoS₂-based catalysts while taking into consideration the support's type and the reaction atmosphere's effects. The impact of catalyst acidity on product distribution and conversion was evaluated; it was discovered that, although acidity had no direct effect on total conversion, it did influence product yields.
HRTEM microscopy, UV spectrum analysis of pyridine adsorption, scanning electron microscopy, X-ray photoelectron spectroscopy, and N₂ physisorption was used to evaluate supports and catalysts. The reactions were carried out under helium reaction atmospheres in a fixed-bed reactor.

Audience take-away:

• Supported transition metal sulfides, such as (K)(Co, Ni, Fe)MoS₂, as a viable catalyst for ethanol dehydrogenation.????
• The effect of the textural features of the catalyst, namely the surface area and volume (micropores and mesopores), on the synthesis of oxygenated hydrocarbons.
• The influence of active phase composition on catalytic activity is being investigated with the goal of controlling the ratio of liquid products to hydrocarbons.

Biography:

Mr Tshepo Dipheko studied Chemistry at North-West University in South Africa and graduated in 2016 with a Master of Science. He subsequently continued his PhD studies at the Peoples' Friendship University Russia in collaboration with Zelinsky Institute of Organic Chemistry, Russian Academy of Science. He is now pursuing a PhD in Chemistry Sciences. His doctoral research now focuses on the synthesis of oxygenated hydrocarbons from CO/H₂ and direct-ethanol conversion over supported transition metal sulfides catalysts, specifically supported (K)(Co, Ni, Fe)MoS₂-based catalysts.