Research Oncharacteristics Of Co-pyrolysis Of Biomass Components And Corn Straw With Typical Hydrogen-enriched Feedstocks

Biomass pyrolysis oil is a research hotspot in the field of biomass energy utilization.However,the biomass itself has the characteristics of hydrogen deficiency and polyoxygenation,and the bio-oil also has problems such as insufficient content of favorable components and high acidity.In this paper,the optimization of biomass catalytic pyrolysis oil production from three biomass components,corn stover and hydrogen-enriched feedstock co-pyrolysis was carried out.The main components of biomass are cellulose,hemicellulose(using xylan as a molding)and lignin as biomass feedstocks,and polyethylene,methanol and ethanol were used as hydrogen-enriched feedstocks.Fourier transform infrared spectroscopy confirms that polyethylene is the most active hydrogen-enriched feedstock of the three biomass components.Polyethylene has the most comprehensive effect on the promotion of hydrocarbon groups and the inhibition of oxygen-containing groups.Thermogravimetric mass spectrometry(TG-MS),pyrolysis-gas chromatography-mass spectrometry(Py-GC/MS)and fluidized bed pyrolysis experiments were used to study the synergistic effect of three biomass components and polyethylene respectively and the copyrolysis effects of three biomass components.In the Py-GC /MS experiments,the main pyrolysis products of cellulose are carbohydrates,with a relative content of 41.1%,and the relative content of hydrocarbons is 14.6%.The main pyrolysis products of xylan are aldehydes and acids,with the relative content of 39.7% and 30.4% respectively,and the relative content of hydrocarbon products is 8.4%.The main pyrolysis products of lignin are phenols,with a relative content of 40.2%,and hydrocarbon products with a relative content of 11.2%.After the addition of polyethylene into pyrolysis,the main oxygen-containing substances in the pyrolysis products of three biomass components shows a downward trend,with the relative content decreasing by more than 10%,while the relative content of hydrocarbon products increases by more than 25%.Among the three biomass components,xylan and polyethylene have the best synergistic effect.The reaction intermediates formed in the pyrolysis process are conducive to deoxidation and aromatization.The hydrocarbon yield increased by 31.2% after the addition of polyethylene,which is the highest among the three components.However,lignin,whose pyrolysis reaction intermediate is the benzene ring structural unit,is difficult to form a good interaction with polyethylene.The relative content of hydrocarbon products is increased to 29.7%,and the pyrolysis synergistic effect is the worst among the three components.In the co-pyrolysis of biomass components,xylanan is the least affected,cellulose is the second and lignin is the highest.Lignin produces more solid products in the pyrolysis process,which will seriously affect the overall pyrolysis efficiency of biomass components.The relative content of specific products in the fluidized bed pyrolysis experiment is different from that in the Py-GC/MS experiment to some extent,but they are basically the same in the general trend of change.Carbon accumulation and coking degree of hzsm-5 molecular sieve during pyrolysis and the effect of adding polyethylene on carbon accumulation and coking degree of hzsm-5 molecular sieve were studied.The results show that the hzsm-5 molecular sieve will produce obvious carbon deposition and coking effect in the pyrolysis process,and the coking degree is more serious in general.With the addition of polyethylene,the degree of carbon deposition of hzsm-5 molecular sieve increased,while the degree of coking decreased significantly.Based on the hzsm-5 used in the three-component fluidized bed pyrolysis experiment,the catalytic effect of hzsm-5 when polyethylene was added remained at 29~35% after pyrolysis.In general,the addition of polyethylene has a positive effect on the retention of catalytic activity of hzsm-5 molecular sieve,extending its service life.