Pretreatment of bio-oil with ion exchange resin to improve fuel quality and reduce char during hydrodeoxygenation upgrading with Pt/C

To obtain high-quality biofuel, bio-oil obtained from fast pyrolysis of woody biomass was pretreated with ion exchange resin (amberlyst 36) at 50 degrees C, 100 degrees C, and 150 degrees C, and then the recovered liquid product was upgraded using hydrodeoxygenation (HDO) with Pt/C at 300 degrees C. After the two-stage upgrading, 4 types of products (gas, light oil, heavy oil, and char) were obtained. Two-immiscible liquid products were consisted of organic heavy oil, derived from bio-oil, and aqueous light oil, based on the ethanol. The mass balances of the HDO products were influenced by the pretreatment temperature. Ion exchange pretreatment of bio-oil was effective in reducing the char formation during the hydrodeoxygenation (HDO) process. The pretreatment also improved the following heavy oil properties: the water content, heating value, viscosity, acidity, and oxygen level. As a parameter used to indicate the biofuel acidity, the total acid number (TAN) value, was clearly reduced from 114.5 (bio-oil) to 34.1-78.2 (heavy oils). Furthermore, the water and oxygen contents of bio-oil (21.1 and 52.6 wt%, respectively) declined after the pretreatment followed by HDO (ranged 5.1-6.9 and 19.0-25.5 wt%, respectively), thereby improving its higher heating value (HHV) from 17.2 MJ/kg (bio-oil) to 26.2-28.1 MJ/kg (heavy oils). The degree of deoxygenation (DOD) increased as the pretreatment temperature decreased, and the highest energy efficiency (79.8%) was observed after pretreatment at 100 degrees C. In terms of catalyst deactivation during the reaction, both carbon deposition and surface cracking intensified with increasing pretreatment temperatures.

Automated summary

Pre-treatment of bio-oil with ion exchange resin and upgrading through hydrodeoxygenation process can significantly improve the properties of biofuels, enhancing heating value and reducing acidity.