Preparation of refined bio-oil by catalytic transformation of vapors derived from vacuum pyrolysis of rape straw over modified HZSM-5

This work aimed to develop an in-situ upgrading process for production of refined bio-oil from primary biomass pyrolysis vapors. The phosphorus, zinc and titanium modified HZSM-5 were developed and first employed in the process. The yield of refined bio-oil was in the range of 17.85-19.97% along with low oxygen content (18.06-20.04%), high pH value (4.96-5.02), low dynamic viscosity (5.85-6.02 mm2/s), high HHV (higher heating value) (32.70-33.98 MJ/kg) and high hydrocarbon content. However, the composition of hydrocarbon varied with modified elements, so the catalytic mechanism of modified HZSM-5 was discussed. Simultaneously, anti-coking performance of modified catalyst was investigated to evaluate sustainability of the process. This work demonstrated that the refined bio-oil produced in this study basically met the technical requirements of combustion in power machinery, which provided a useful way to utilize renewable lignocellulose biomass. Though anti-coking capability of modified HZSM-5 was enhanced, coke deposition still hindered the continuous production of refined bio-oil to a certain extent.