The Experimental Study On Co-catalytic Cracking Of Bio-oil And Waste Cooking Oil

Bio-oil is the liquid product of biomass fast pyrolysis and can be used as thealternative fuel of fossil oil. But bio-oil has the disadvantage of poor stability, strongacid and high moisture content. Thus, it cannot be applied to the engine directly andupgrading process is necessary. Catalytic cracking of bio-oil meets the problem of lowupgrading oil production rate and the catalyst deactivation. Therefore, co-catalyticcracking of waste cooking oil and bio-oil were considered in this paper, aiming atincreasing the yield of aromatic hydrocarbon and lowering the coke formation rate.Catalytic cracking of the bio-oil compound （acetic acid, acetol, guaiacol,n-heptane, cyclohexane and ethyl acetate）, model compound （acetic acid） blendedwith waste cooking oil and bio-oil blended with waste cooking oil was studied in theself-made catalytic cracking device using commercial molecular sieve HZSM-5inthis paper. It was found that:The gas product of model compound showed the trend that olefins contentreduced, alkanes content increased, while aromatic hydrocarbon content of the liquidproduct increased and the oxygenic phenols content decreased with the increase ofcatalyst dosage after catalytic cracking. The catalyst dosage had obvious effect oncoke retained on the catalyst of acetic acid and had no obvious effect on acetol byTG-DSC. Increasing Catalyst dosage can effectively increase the content of aromatichydrocarbon and other stable material in ethyl acetate liquid product.Catalytic cracking mechanism: HZSM-5provides hydrion-H+to conjugate withoxygen in model compound. Then the water molecules are removed formingcarbocation. All kinds of carbocation fracture α, β key or are dehydrogenized formingC₂double bond ion and CH₃⁺and all the ions form cycloparaffin of six carbons. Thecycloparaffin becomes aromatic hydrocarbon by dehydrogenation and the materials ofnot removing oxygen form phenol and benzene ketone and so on.After bio-oil blended with waste cooking oil, the phenol which have high oxygencontent disappeared in liquid product. Although aromatics content decreased, butliquid product yield increased obviously and gas yield decreased. Catalytic crackingeffect can be obviously improved and aromatic hydrocarbon content increased whenbio-oil was blended with waste cooking oil. Bio-oil blended with waste cooking oil can retain carbon deposit on the catalysts by TG-DSC. With reaction time increasing（2h to5.75h）, unstable material olefins content reduced, light aromatic hydrocarboncontent of benzodiazepines increased, anthracycline-based aromatics contentessentially unchanged and naphthalene ring produced in liquid product. The possiblereason may be that more B acid was produced on the catalyst surface with reactiontime increasing. B acid making the benzodiazepines aromatic hydrocarbon selectivelyincreased had produced good effect on light aromatic hydrocarbonWaste cooking oil processing problems and bio-oil quality improving can besolved in the research, which provides a theoretical basis for preparing chemicals ofaromatic hydrocarbon.