Ethanol petrochemical synthesis

HPAs, however, is their solubility in polar solvents or reactants, such as water or ethanol, which severely limits their application as recyclable solid acid catalysts in the liquid phase. Nonetheless, they exhibit high thermal stability and have been applied in a variety of vapor phase processes for the production of petrochemicals, e.g. olefin hydration and reaction of acetic acid with ethylene [100, 101]. In order to overcome the problem of solubility in polar media, HPAs have been immobilized by occlusion in a silica matrix using the sol-gel technique [101]. For example, silica-occluded H3PW1204o was used as an insoluble solid acid catalyst in several liquid phase reactions such as ester hydrolysis, esterification, hydration and Friedel-Crafts alkylations [101]. HPAs have also been widely applied as catalysts in organic synthesis [102]. 

The use of renewable feedstocks (i.e., biomass) in the production of fuels and value-added chemicals has attracted major interest from researchers and governments because of the anticipated shortages of traditional petrochemical industrial feedstocks [199]. An excellent overview of the milestones relating to the use of bioderived alcohols in the synthesis of higher value chemicals was recently presented by Hutchings et al. [200]. In this area as well, particle size effects can be identified yet care must be taken, as illustrated by a recent paper by Simakova et al. [201], which showed a bimodal Au particle size effect in the catalytic activity of Au-TiOj system in the gas-phase oxidation of ethanol. 

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