Studies Of Co-pyrolysis Of Oil Sahle And Biomass

As a kind of unconventional fossil fule,oil shale could produce oil and gas through pyrolysis,which makes it more and more attractive for those countries short of crude oil.Pyrolysis of oil shale has been industrialized,however,the technologies suffer from low oil yield and poor oil quality.Hence,the key factor of promoting the oil-shale utilization is to solve these problems.Biomass is an abundant sustainable resource,and has been widely studied to produce oil and gas by pyrolysis.The oil and gas from biomass suffer from low heat value.Pyrolysis mechanisms show that co-pyrolysis of oil shale and biomass may combines the advantages,which can solve the problem of separate pyrolysis.Although the reseach has been widely reported,the experimental rule and research results are different.It is well known that biomass is mainly composed of cellulose and lignin.The different behaviors exhibited by different biomass may be related to the contents of cellulose and lignin are different.However,the specific roles that cellulose and lignin play in the process of co-pyrolysis are still not clear.Herein,in this paper,we use cellulose and lignin co-pyrolyzed with oil shale,and the weight loss,product yield and quality of oil were investigated by thermogravimetry,two-stage fixed bed reactor and simulated distillation.(1)The co-pyrolysis of oil shale and cellulose had positive synergistic effect.Compared with separate pyrolysis,co-pyrolysis has an increasing tendency among the yield of liquid and gas,the contents of CH4 and C3H8 in the gas products,and the proportion of gasoline and diesel in the liquid products,while the content of vacuum residue decreased significantly(i.e.a part of heavy components were converted into light components and the quality of oil was improved).In addition,the release of cellulose volatiles is delayed,and the rate of weight lose is greater than the theoretical value in the overlap pyrolysis stage of cellulose and oil shale.(2)The synergy of co-pyrolysis of cellulose and oil shale may result from the positive influence of shale ash and cellulose volatiles,which reduced residue yield and increased liquid yield.It is probably due to the free radicals generated by cellulose bind with macromolecule free radicals of oil shale,and then prevent them from polycondensation,which could produce more semi coke.The volatiles of oil shale have less influence on cellulose hemi coke,which also proved that the reason of why the weight lose of oil shale between 380-520 ? is less than the theoretical value,is that some weak bonds in the organic matter of oil shale are pyrolyzed ahead under the influence of cellulose,resulting in reduce of organic matter that could be pyrolyzed during this period.(3)The co-pyrolysis of oil shale and lignin basically has no or very few effect on distribution of products and the composition of gas.The light components of the mixed oil increased,it is probably due to the small radical generated by lignin stabilizes some macromolecular radicals of oil shale.The oil shale ash has little effect on the pyrolysis of lignin.The above results show that,cellulose and minerals play more important role of the synergistic effect of co-pyrolysis,whereas lignin is less important.