Study On Biomass-assisted Catalytic Upgrading And Viscosity Reduction Of Heavy Oil

With the increasing development of industry,the consumption of energy is multiplying,the conventional oil reserves are decreasing,and the exploitation and utilization of heavy oil attracted more and more attention.Heavy oil is a very important part of petroleum resources,has more than 10 times the reserves of conventional oil resources but lowers extraction and transportation efficiency due to its high content of gums and asphaltene,thus upgrading of heavy oil that improve the quality and reduce the viscosity irreversibly has very important practical significance for heavy oil transportation and downstream refining.The pyrolysis of hemicellulose,cellulose and lignin generate a variety of complex organic compounds,the sugar,furan,aldehydes,ketones and carboxylic acids could generated from the pyrolysis of cellulose and hemicellulose,the phenol,guaiacol,esters,methoxy benzene,methoxyacetyl benzene and other strongly polar organic compounds could generated from the pyrolysis of lignin.The use of biomass pyrolysis products as a hydrogen donor and viscosity reducer,hydrogen donor could enhance the cracking depth of heavy oil,viscosity reducer could decrease the heavy fragments mass fraction and inhibit the aggregation of soluble asphaltene,which can effectively reduce viscosity and improve the quality of heavy oil.6 kinds of oil-soluble metal catalysts were synthesized in this research,nine kinds of waste biomass,such as cotton stalk,coconut shell,arugula,bagasse,magnolia grandiflora,oil cake as raw material,Liaohe heavy oil was used to study the viscosity reduction in high temperature and pressure reactor.The effects of biomass type,catalyst type,catalyst content,biomass content,reaction temperature and reaction time on the viscosity reduction of heavy oil were investigated respectively.The optimal reaction conditions were as follows:under the content of sawdust was 5%,the content of catalyst PASC was 0.05%and the reaction temperature was 350?for 30 min,the viscosity of heavy oil decreased from 22210 mPa·s to 430 mPa·s,the content of saturated and aromatic from 32.00%and 20.46%to 39.30%and 22.37%,respectively.The content of asphaltene decreased 13.12%while the content of asphaltene increased 3.91%,the average molecular weight of heavy oil decreased from 942 g/mol to 648 g/mol,the fraction under 500? increased from 34%to 60%,the quality of heavy oil improved significantly.The acids,aldehydes and furans produced by biomass pyrolysis provide free hydrogen radicals,which can partially inhibit the condensation reaction of small molecules formed by the pyrolysis of heavy oil.The dilute action of the alkanes reduces the concentration of carbon ions and reduces their collision opportunities,the esters,aromatic hydrocarbons and other substances undermine the heavy oil colloidal structure,the sheet-like structure in original asphaltene was changed into into loose fragments,which weakening the interaction between the colloidal structure.The study also found that the pyrolysis reaction of resin reaction and the condensation of resin into asphaltene in the catalytic reaction with the assistance of biomass pyrolysis is pseudo-first orderreaction,and the activation energy of resin and asphaltene were 33.5420 kJ/mol and 29.8256 kJ/mol,respectively.