A novel method of upgrading bio-oil by reactive rectification

Zirconium-containing mesoporous molecular sieve SO42−/Zr-MCM-41 was synthesized and used as a catalyst in upgrading bio-oil through reactive rectification. The suitable operation conditions for bio-oil upgrading were obtained as follows: catalyst usage based on bio-oil = 4%; reflux ratio = 1: 6; mass feed ratio of bio-oil : ethanol : hydrogen peroxide (aqueous solution 30%) = 1 : 0.5 : 0.4. The yield of light oil was up to 21.4%. Under these conditions, two kinds of upgraded bio-oils (light oil and heavy oil) were obtained; their densities were reduced from the original 1.16 kg/m3 to 0.91 kg/m3 and 0.95 kg/m3, water content from 33% to 0.5% and 5.0%, whereas, the gross calorific value increased from the original 14.3 MJ/kg to 21.5 MJ/kg and 24.5 MJ/kg, and the pH value from 2.82 to 7.06 and 5.35, respectively. The volatile organic acids were converted into esters under the action of the solid acid catalyst SO42−/Zr-MCM-41, whereas, the heavy oil was composed of nonvolatile components in the original bio-oil.