The Catalytic Activity of TCA-Modified Indonesian Natural Zeolite During the Esterification of Sengon Wood Bio-Oil

Abstract

The bio-oil produced from the pyrolysis of biomass is highly corrosive due to the high content of organic acids. These organic acids could be removed through an appropriate upgrading process, i.e., esterification using alcohols to form less polar esters. In this study, the bio-oil used as the feedstock in the esterification was produced from the pyrolysis of Sengon wood with a particle size of 297 µm at 600 °C. The esterification was performed at 70 °C in the presence of a trichloro acetic acid (TCA)-modified Indonesian H-zeolite catalyst with various weight ratios of bio-oil-to-methanol and reaction times under a constant stirring rate of 500 rpm. The esterification progress was indicated by the decrease in the total acid number of the bio-oil after esterification. No significant coke formation (< 0.05 wt%) was observed indicating that the suppression of repolymerisation could be achieved. This study showed that the esterification underwent in a fast rate, indicated by the decrease in the total acid number of the bio-oil by 47.85 % only over a 15-min esterification. Compared to the uncatalysed esterification, the TCA/zeolite-catalysed esterification showed a higher decrease in the total acid number of the bio-oil up to 65.83 %, due to the conversion of the carboxylic acids to esters. HIGHLIGHTS The TCA-modified Indonesian natural zeolite catalyst has been successfully prepared The presence of the TCA/Indonesian natural zeolite during the esterification of bio-oil produced from the pyrolysis of Sengon wood could greatly suppress the severe repolymerisation leading to coke formation The TCA/Indonesian natural zeolite-catalysed esterification of Sengon bio-oil underwent in a fast rate The TCA/Indonesian natural zeolite catalyst showed a good performance in this study in comparison with the uncatalysed esterification GRAPHICAL ABSTRACT