| Bioenergy has obtained extensive attention in current years for its renewable and sustainable natures and is expected to replace fossil energy in the next few years.Pyrolysis oil is a kind of oil-like liquid products,obtained by pyrolysis of biomass.However,several disadvantages of pyrolysis oil,including poor stability,high acidity and corrosively as well as high oxygen content and high water content,limit its direct use.Therefore,upgrading process is necessary to improve their physiochemical properties before being used as transportation fuel or as refinery feedstock.Esterification is a potential route to convert the organic acids in pyrolysis oil by reacting them with alcohol or phenol presenting in pyrolysis oil.For this purpose,acetic acid and phenol were chosen as the model chemicals in pyrolysis oil,three types of zeolites H-Beta?Si/Al ratio 25?,H-USY?Si/Al ratio 11?,H-Y?Si/Al ratio 5.4?have been used as catalysts for esterification of acetic acid and phenol in toluene.The catalysts have been characterized using N2 sorption analysis?BET?,X-ray diffraction?XRD?and NH3-temperature-programmed-desorption?TPD?techniques.Acetic acid conversion and the yield of phenylacetate were calculated.The results showed zeolite H-Beta was the most active for this reaction where the conversion of acetic acid was49.07%and the yield of phenyl acetate ester was 32.01%,and from GC results there is no peak appear for other product.The low activity of H-Y,H-USY can be explained as the low Si/Al ratios which increase the affinity of the zeolite towards water to adsorb on the surface of the zeolite and cause deactivation of the catalyst and thus a drop-in conversion.The effects of reaction conditions such as catalyst amounts,mole ratios of the reactants,the reaction time,the reaction temperature were investigated to optimize the reaction.The experimental conclusions herein are useful for the development of catalytic esterification of pyrolysis oil. |
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