Effect of Pd, Ru, Ni and ceramic supports on selective deoxygenation and hydrogenation of fast pyrolysis Jatropha residue vapors

Catalytic upgrading of the pyrolytic vapors after fast pyrolysis of Jatropha residue was performed using analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) at 673–873 K. The Py–GC/MS analyses for pyrolysis vapors show a range of aromatic hydrocarbons, hydrocarbon compounds, phenols, alcohols, aldehydes, ketones, acids and esters, furan and N-containing compounds. The result showed that high temperature had positive influence on the yields of pyrolytic products. Catalytic testing was performed by using Al2O3, ZrO2 based catalysts and their modified ones with impregnation of Pd, Ru, and Ni, respectively. The Al2O3 and ZrO2 were impregnated with CeO2 to promote metal dispersion prior to deposition of Pd, Ru, or Ni. From the experiment, these catalysts showed some potential to convert the highly oxygenated compounds to aromatic and hydrocarbons. The hydrocarbon yields increased with increasing catalyst to Jatropha ratio in all catalysts. The hydrocarbon selectivity was Ni–Ce/Al2O3 > Al2O3 > Ce/Al2O3 > Pd–Ce/Al2O3 > Ru–Ce/Al2O3 in Jatropha to catalyst ratio of 1:5. Pd–Ce/Al2O3 was the most effective in terms of increased aromatic and hydrocarbon compounds, decreased oxygenated and N-compounds. Though Al2O3 increased favorable aromatic and hydrocarbon compounds with completely elimination of acid but it also promoted adverse N-containing compounds. Activities of Ru–Ce/Al2O3 were similar to Ce/Al2O3 except for the selectivity toward acid compounds. Comparing to ZrO2 catalysts, all Al2O3 based catalysts displayed relatively higher activity toward deoxygenation reactions which resulted in low quantity of carboxylic acids and other oxygenated compounds while enhanced yields of aliphatic and aromatic hydrocarbons. Al2O3 had surface area of 103.38 m2/g while surface area of ZrO2 was 12 m2/g, indicating that catalyst with high surface area had better catalytic activity. However, Al2O3 catalysts seemed to promote N-compounds suggesting that further denitrogenation is required while pyrolysis with ZrO2 had disadvantage on high yield of acid which could cause the corrosion problem. Nevertheless, overall performances of these two support catalysts are acceptable and can be considered as good candidates for bio-oil upgrading catalysts.