Catalytic esterification of bio-oil by ion exchange resins

Upgradation of bio-oil before utilization is desirable to obtain high grade fuel because of its drawbacks like high viscosity, low heating value, poor stability and high corrosiveness. Organic acids in bio-oils can be converted to their corresponding esters by catalytic esterification and this greatly improved quality of bio-oils. We selected 732 and NKC-9 type ion exchanger resins as esterification catalysts for upgrading bio-oil. The catalytic activity was first investigated by model reaction. The esterification of bio-oil with methanol was conducted in a batch reactor. Acid numbers of upgraded bio-oil on 732 resin and NKC-9 resin were lowered by 88.54% and 85.95%, respectively, which represents the conversion of organic acids to neutral esters; the heating values increased by 32.26% and 31.64%, respectively; the H2O contents decreased by 27.74% and 30.87%, respectively; the densities were lowered by 21.77% for both and the viscosities fell by approximately 97%. A fixed bed reactor was used for continuous catalytic esterification of bio-oil on 732 resin, and the acid number remarkably decreased by 92.61%. The accelerated ageing test showed improvement of stability, and the aluminum strip corrosion test showed reduced corrosion rate of bio-oil after upgradation.