(700f) Hydrodeoxygenation of Acetic Acid As a Model Compound for the Aqueous Phase Catalytic Pyrolysis Oils

Authors: 
Jahromi, H., Utah State University
Agblevor, F., Utah State University
Catalytic pyrolysis of biomass generates organic, aqueous, gaseous and solid fractions. The organic fraction can be easily hydrotreated to produce hydrocarbons, but the aqueous phase that contains between 10 to 25% soluble organics can pose challenges in wastewater treatment. The aqueous fraction from the catalytic pyrolysis of Pinyon Juniper wood was characterized for its organic content. The fraction contained about 15 wt% organic compounds determined from Karl Fischer analysis. The organic fractions were further characterized using gas chromatography and mass selective detection (GC/MS). The analysis showed that the dissolved organics were composed of acetic acid, ketones, aldehydes, and phenolic compounds. In this study we investigated the hydrodeoxygenation (HDO) of 15 wt.% acetic acid solution to represent aqueous phase Pinyon Juniper catalytic pyrolysis oil (APPJCPO). HDO experiments were carried out at different temperatures (150, 250, 350, and 450 °C) using Ni/SiO2-Al2O3 catalyst in a high pressure Parr reactor. HDO of acetic acid produced acetaldehyde, ethanol, ethyl acetate, carbon dioxide, methane, ethane, and coke at different concentrations depending on the reaction temperature. Reaction pathways of acetic acid HDO were proposed based on analysis of the products. The final products of acetic acid HDO were methane, water at reaction temperature of 450 °C. HDO of APPJCPO was carried out at 450 °C. During HDO the pH of APPJCPO increased from 2.97 to 6.93. The final products of HDO of APPJCPO were water and methane. After HDO experiments, the catalyst was partially deactivated due to coke formation. This study provided insight in the reaction network of acetic acid HDO and suggests that HDO is a promising technique to overcome toxicity and corrosion of aqueous phase pyrolysis oil.