Ethanol from syngas

Ethanol and Higher Alcohols from Syngas. Direct synthesis of ethanol from syngas is intensely investigated especially in North America. Another approach in this context is the homologjzation of methanol, i.e. the reaction of methanol with syngas to yield ethanol. Higher alcohols can also be formed. The reactions are summarized in equations (8.3) and (8.4). 

Ethanol from ethane is a fossil-based fuel and must be distinguished from grain alcohol. Ethanol from syngas has been extensively studied, but catalysts have not been found, as yet, to be efficient enough to make the process cost-effective. Similarly, the conversion of syngas to ethanol by alternate routes has been considered ... 

Liu, K., et al., 2012. Eermentative production of ethanol from syngas using novel moderately alkahphilic strains of Alkalibaculum bacchi. Bioresource Technology 104, 336-341. 

The inner cavity of carbon nanotubes stimulated some research on utilization of the so-called confinement effect [33]. It was observed that catalyst particles selectively deposited inside or outside of the CNT host (Fig. 15.7) in some cases provide different catalytic properties. Explanations range from an electronic origin due to the partial sp3 character of basal plane carbon atoms, which results in a higher n-electron density on the outer than on the inner CNT surface (Fig. 15.4(b)) [34], to an increased pressure of the reactants in nanosized pores [35]. Exemplarily for inside CNT deposited catalyst particles, Bao et al. observed a superior performance of Rh/Mn/Li/Fe nanoparticles in the ethanol production from syngas [36], whereas the opposite trend was found for an Ru catalyst in ammonia decomposition [37]. Considering the substantial volume shrinkage and expansion, respectively, in these two reactions, such results may indeed indicate an increased pressure as the key factor for catalytic performance. However, the activity of a Ru catalyst deposited on the outside wall of CNTs is also more active in the synthesis of ammonia, which in this case is explained by electronic properties [34]. 

Chemicals from Syngas A wide range of products can be produced from syngas. These include such chemicals as methanol, ethanol, isobutanol, dimethyl ether, dimethyl carbonate, and many other chemicals. Typical methanol-producing reactions are... 

An approach to the production of ethylene from biomass that does not involve pyrolysis is ethanol dehydration. The catalytic conversion of syngas to ethanol from low-grade biomass (or fossil) feedstocks, and fermentation ethanol via advanced cellulose hydrolysis and fermentation methods, which make it possible to obtain high yields of ethanol from low-grade biomass feedstocks as well, are both expected to be commercialized in the United States (Chapter 11). Which technology becomes dominant in the market place has... 

There is more uncertainty associated with ethanol production from syngas. SG = Synthesis Gas, F = Fermentation (Spath and Dayton, 2003). 

For the production of higher alcohols from syngas, two kinds of perovskites have been reported in the literature. First, perovskites with noble metals, like LaRhOs, have been studied in the past [23,24] for the ethanol synthesis with a CO/H2 mixture. More recently, LaCoi Cu 03 perovskites have been investigated to explore the opportunity of the Ci-C alcohols synthesis following an Anderson-Schulz-Flory (ASF) distribution [25-32] similar to that obtained by the so-called Co-Cu IFP catalyst [33]. 

BioUquids such as methanol and ethanol are also attractive bio-fuels for some fuel cell systems. Methanol is proposed as a fuel for FCVs. Methanol can be synthesised from syngas that may be derived from biomass or natural gas. Ethanol can be produced directly by fermentation of biomass. Alcohols are attractive also because of the ease with which they can be reformed into hydrogen-rich gas. This is necessary if the reforming is to be carried out onboard a fuel cell vehicle. 

Two theoretical products from syngas which are frequently subject to research are ethanol and liquified petroleum gasoline (LPG) [38,39]. In the case of ethanol, direct synthesis from syngas over a rutheniimi catalyst has been demonstrated but selectivity is rather low. LPG is suggested to be produced over methanol, DME, olefins, and hydrogenation to C3/C4 fractions. 

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