Analysis of coke precursor on deactivated catalyst in bio-oil upgrading process

Characterization of coke precursor on deactivated catalyst in bio-oil upgrading under CO atmosphere was analyzed with thermogravimetry, X-ray diffraction, infrared analysis, scanning electron microscopy, and nuclear magnetic resonance. The results showed that the deposition of coke precursor on a catalyst surface was mainly low-boiling point of saturated hydrocarbon compounds and the coke precursor of internal channels of deactivated catalyst were major aromatic hydrocarbon compounds. The coke precursor was in an amorphous state, which was highly dispersed on the catalyst surface or into the catalyst micropore. In addition, the catalyst deactivation mechanism was speculated that the small molecule aromatic compounds entered the internal channels of a catalyst and formed macromolecular aromatic hydrocarbons by aromatization gradually, further condensed to form coke and obstructed the channels of the catalyst.