Integrated catalytic hydrodeoxygenation of Napier grass pyrolysis vapor using a Ni_2P/C catalyst

摘要

A series of nickel phosphide/activated carbon (Ni2P/C) catalysts with varying nickel loading levels and nickel-to-phosphorous molar ratios (Ni:P) were synthesized by wet co-impregnation and treated by temperature programed reduction. The Ni2P phase was clearly present in the Ni2P/C catalyst with a Ni: P ratio of 1.5 and a 5.37 mmol Ni loading level. The catalysts were then evaluated for the hydrodeoxygenation of the pyrolysis vapor derived from the integrated pyrolysis and upgrading of Napier grass, with two fixed bed reactors in series, at different upgrading temperatures and space velocities. The reaction could be carried out at atmospheric pressure. The maximum bio-oil yield was obtained at an upgrading temperature of 340 degrees C, while the major components of the bio-oil were phenolic compounds ( 50%). An upgrading temperature of 360 degrees C did not only present dehydration but aromatization was also predominant. Moreover, the phenolic compounds decreased with increasing space velocity. The oxygen content in the pyrolysis vapor was catalytically removed via the dehydration pathway, which significantly decreased the oxygen/carbon ratio from 0.24 to 0.17. Due to advantages spanning from highly efficient deoxygenation activity to the requirement of mild conditions, the Ni2P/C catalyst shows great potential as a catalyst for bio-oil upgrading.