The selective catalytic conversion of biomass-derived syngas into ethanol is thermodynamically feasible at temperatures below roughly 350 degrees C at 30 bar. However, if methane is allowed as a reaction product, the conversion to ethanol (or other oxygenates) is extremely limited. Experimental results show that high selectivities to ethanol are only achieved at very low conversions, typically less than 10%. The most promising catalysts for the synthesis of ethanol are based on Rh, though some other formulations (such as modified methanol synthesis catalysts) show promise.

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The effect of Li and Mn promoters on the structure and selectivity of supported Rh catalysts for CO hydrogenation reaction was examined. Infrared spectroscopy and X-ray absorption were used to investigate the adsorption of reactants and local structure of Rh. These techniques were used in combination with reactivity, H2 chemisorption, and temperature programmed studies to correlate structural characteristics with activity and selectivity during CO hydrogenation of unpromoted Rh/TiO2 and three promoted Rh catalysts: Rh–Li/TiO2, Rh–Mn/TiO2, and Rh–Li–Mn/TiO2. The presence of a promoter slightly decreases the Rh clusters size; however, no evidence for an electronic effect induced by the presence of Li and Mn was found. Higher turnover frequencies were found for the promoted catalysts, which also showed the lower dispersion. The Li promoter introduces a weakened CO adsorption site that appears to enhance the selectivity to C2+ oxygenates. The selectivity to C2+ oxygenates varies inversely with the reducibility of Rh metal, that is, the lower the Rh reducibility, the higher the selectivity.

Concerns over global climate change have led to strong research emphasis worldwide on reducing the emission of greenhouse gases like CO 2 . One avenue for carbon emission reduction is using CO 2 capture and storage from industrial sources. Having low toxicity and low vapor pressure and being resistant to oxidation, natural amino acids could be a better choice over current carbon capture materials. In this study, we pioneered a unique phase change amino acid salt solvent concept in which amino acid salt solution was turned into a CO 2 -rich phase and a CO 2 -lean phase upon simple bubbling with CO 2 and most importantly, this solution captured the most CO 2 (~90%) in the CO 2 -rich phase. Bicarbonate was found to be dominant in the CO 2 -rich phase, which had a high CO 2 loading capacity and good regenerability and cycling properties. Such a phase change amino acid salt solvent may provide unique solutions for industries to reduce CO 2 and other harmful emissions.

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