Evaluation of bio-char based products as hydrotreating catalysts for the production of renewable fuel

Abstract

Increasing demand for alternative fuel from fossil fuel exists which has led to the development of new technologies for the production of bio-fuels. One such technology involves the hydrotreatment of vegetable oils such as cottonseed oil to produce bio-hydrocarbons. The catalyst plays an important role in the hydrotreatment process and also makes up a significant part of the cost of hydrotreatment. The utilization of waste titanium tetrachloride in the production of hydrotreating catalysts could result in a situation where a waste material is transformed into useful product. Products from the hydrothermal liquefaction process was tested as catalysts during hydrotreatment of cottonseed oil. Five catalysts were prepared and tested as follows: 1) biochar produced at 260 °C, 2) Biochar produced at 320 °C, 3) ash of the 260 °C biochar, 4) ash of the 350 °C biochar and 5) the 320 °C biochar heated to 900°C under nitrogen atmosphere. Cottonseed oil was hydrotreatment in a 350 ml batch reactor using the 5 different catalysts. This was done under hydrogen atmosphere with an initial hydrogen pressure of 9 MPa, a retention time of 1 hour at a reaction temperature of 410°C. The liquid product produced using the 5 catalysts was compared with the liquid product produced with a commercial NiMo hydrotreating catalyst. The 320 °C biochar yielded the highest n-alkane content with a liquid product composition similar to that of the commercial NiMo hydrotreating catalyst as well as the fuel with the highest energy value of all 5 catalysts of 45.47 MJ/kg. The conversion of cottonseed oil for the 5 catalysts was lower compared to that of the commercial catalyst showing that direct co-liquefaction of the biomass with the metal does not result in a hydrotreating catalyst with high enough catalyst activity