Journal of Advanced Chemical Engineering

An investigation into the effect of alkali promoters and catalytic supports over the selectivity of higher alcohols from syngas using molybdenum carbides

2^nd International Conference on Advances in Chemical Engineering and Technology

November 16-17, 2017 | Paris, France

Waqas Aslam, Muxina Konarova, Masih Rashidi and Jorge Beltramini

Australian Institute for Bioengineering & Nanotechnology, Australia

Posters & Accepted Abstracts: J Adv Chem Eng

Abstract:

Statement of the Problem: Higher alcohols including ethanol, propanol and butanol have emerged as one of the most promising renewable fuel in the recent years. The formation of higher alcohols from syngas comprises of complex intermediate steps and in spite of extensive research, fabrication of an efficient bifunctional catalyst for conversion of syngas to higher alcohols remains challenging. The objective of this research is to develop a highly stable and active molybdenum carbide based catalyst to enhance the alcohols yield from biomass derived Syngas (H2/CO = 2). Methodology & Theoretical Orientation: Molybdenum carbide (Mo2C) based catalysts were synthesized over three different kinds of supports i.e., γ-Alumina (acidic), Activated Carbon (neutral) and Magnesium Oxide (alkaline). The supported molybdenum carbides were further promoted with potassium carbonate (K2CO3). The CO hydrogenation reaction was carried out under a high pressure, 60 bar, in a Fixed-bed reactor at 275°C, using WHSV 1500 h-1. Findings: In contrast to Mo2C/Al2O3 and Mo2C/AC the inherent â??basicityâ?? of MgO expedited the alcohols formation. However, over Mo2C/MgO, the CO conversion was considerably less (~10%) as compared to ~70% over Mo2C/Al2O3 and Mo2C/AC. The results of characterisation from X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction analysis (XRD) and Temperature Programmed Reduction indicated the presence of â??high-valent molybdenum speciesâ?? after K2CO3 incorporation. The strong â??Lewis acid sitesâ?? present on Mo2C/Al2O3 facilitated the dispersion of basic promoter (K2CO3), as a result a maximum yield of higher alcohols (24 g. kgcat-1. h-1) was obtained over K-Mo2C/Al2O3. Conclusion & Significance: Supported molybdenum carbides are inexpensive and efficient catalyst for the conversion of syngas to high-valued biofuels. The increased concentration of high valent molybdenum species over the catalyst surface favours the â??non-dissociativeâ?? adsorption of carbon monoxide and limiting the hydrogenation reaction. Subsequently, shifting the product selectivity remarkably from unwanted reaction products (hydrocarbons and CO2) to alcohols.