Ethanol is flexible energy rich molecule in terms of its synthesis where scientists have optimized the production protocol by Fischer-Tropsch principle to generate alcohol in a cell free medium completely. It involves thermochemical decomposition of pretreated complex fibrous organic residues under controlled oxygenated conditions and high temperatures to initially produce a syngas mixture in a specialized, thermo-tolerant reaction chamber called gasifier which is of several types for work. Syngas liberated will be a mixture with contaminant ash, oils, char etc which need to be conditioned by scrubbers and cyclone seperators etc for catalytic conversion into ethanol. Conditioned syngas is now treated with a chemical catalyst which seems to produce a vast array of products such as methane, butane and octanol, etc and so reactions are accordingly varied to regulate the substrate mass for the production of ethanol to a maximum extent. It is finally followed by alcohol purification involving steaming and dehydration. The depressurized alcohol stream is dehydrated using vapor-phase molecular sieves. The dehydrated alcohol stream is introduced to the main alcohol separation column that splits methanol and ethanol from the higher molecular weight alcohols. This methanol/water mixture is recycled back to the entrance of the alcohol synthesis reactor in order to increase the yield of ethanol.
The catalytic conversion method appears at present to be more advanced than enzymatic conversion inspite of certain critical limitations.
