Esterification of acetic acid in the presence of sulfated clinoptilolite: a model study of upgrading of pyrolysis bio-oil

Abstract

In this study, the esterification reaction of acetic acid with n-propyl alcohol was studied on a sulfated zeolite catalyst to improve the bio-oil obtained by pyrolysis of lignocellulosic biomass. Temperature (323-353 K), sulfuric acid concentration (1-3 M) and time (1-4 hours) were selected as parameters in the preparation of sulfuric acid-modified clinoptilolite samples. Sulfated zeolites samples are characterized by XRF, XRD, and N(2)adsorption/desorption techniques. It was observed that the zeolites treated with sulfuric acid retained their crystal structures, decreased surface areas, and changed SiO2/Al(2)O(3)ratios. Samples modified with sulfuric acid are more effective in the esterification reaction than unmodified zeolite. The increase in sulfuric acid concentration and temperature in the modification process increased the conversion of acetic acid in the esterification reaction. The highest acetic acid conversion (63.8%) was obtained with zeolite treated at 323 K temperature, 3 M sulfuric acid for 1 hour.