Crude oil production and classification of organic compounds on super-critical liquefaction with rice hull

Abstract

The liquefaction of rice hull (a typical agricultural waste) has been conducted with n-butanol solvent at various reaction temperatures ranging from 260 to 320°C. As a result, it was found that biomass conversion rates were increased with increasing temperature up to 320dgC. However, it was observed that its rate of conversion to liquid was about 83% at 320°C for 30 min. The crude oil yield with rice hull increased up to 1,273 mg/g/L at 300°C, but the yield of Fraction 1 at 280°C was raised suddenly, and peaked at 2 times that of the initial input amount of feedstock. Furthermore, the calorific values of crude oil and Fraction 1 from rice hull were about 5,843 and 8,061 kcal/kg and were enhanced 163 and 225%, respectively, relative to its feedstock as rice hull, respectively. Fraction 1 may be suitable as an alternative liquid fuel of gasoline, based on an engine performance test. Sixty species of organic compounds in crude oil were categorized into 8 classes of compounds, including acids, alcohols, aliphatic hydrocarbons, ethers, esters, ketones, phenol, and aromatics, and others. In the crude oil from rice hull, the most common chemical types were esters and ethers accounting for 32.0 and 19.2% of the total extract, respectively. Analysis of Fraction 1 revealed that the main chemical components were C₅H₁₂O, C₇H₁₄O₂, C₈H₁₆O₂, and C₁₂H₂₆O₂. Therefore, for producing clean and green fuel energy with plant biomass liquefaction it is necessary to further investigate crude oil and to further refine Fraction 1 through catalytic cracking or hydro-de-oxygenation (HDO).