Study On Catalytic Co-pyrolysis Characteristics Of Shenfu Coal And Sunflower Stalk

Co-pyrolysis of coal and biomass not only can utilize biomass resources effectively,but also improve coal conversion efficiency. In this paper, co-pyrolysis characteristics ofShenfu coal and Sunflower stalk, which is a special and regnant biomass in north ofShaanxi Province, was investigated in a tubular fixed-bed reactor. Firstly, the pyrolysiscondition of Sunflower stalk was studied. Then, based on the experiments of Shenfu coaland Sunflower stalk co-pyrolysis, a series of iron catalyst with Shenfu coal as the carrierwere prepared, and the effects on co-pyrolysis were analysed detailedly.Effect of condition such as atmosphere, temperature and gas flow rate on thedistribution of products in the pyrolysis of Sunflower stalk were investigated in the tubularfixed-bed reactor. The results of orthogonal experiment show that the best pyrolysisconditions of Sunflower stalk are at600℃with CO2gas flow rate at60mL/min, and thehighest tar yield is27.47%. The tar was also analysed by GC-MS, the results show that themain ingredients of tar are consisted of ketone, phenol, acid, aldehyde, naphthalene, andbenzene. Especially, the content of phenolics is46.58%. The char was analysed by FI-IRspectra, specific surface and pore structure, the results show that no obvious difference canbe found for Sunflower stalk char in different atmosphere, and the average pore size ofchar is48.8nm. The gas products were analysed by GC, and the results show that CO2, H2and CH4atmosphere have involved in the pyrolytic reactions of Sunflower stalk, theirconversion yields are respectively36.9%,35.5%,24.5%in turn.Then, co-pyrolysis characteristics of Shenfu coal and Sunflower Stalk were studied inthe tubular fixed-bed pyrolysis reactor. When Shenfu coal and Sunflower stalk werepyrolysed in different atmosphere, the tar yield is relatively high in H2atmosphere. It isfound that as the mass ratio of Shenfu coal and Sunflower increase, the tar yield fromco-pyrolysis reduce gradually. When co-pyrolysis was studied under H2atmosphere,mSFC:mSSat4:6, gas flow rate at60mL/min, pyrolytic temperature at600℃for1h, and heating rate at10℃/min, the tar yield is22.8%. So there is an additive effect inco-pyrolysis of Shenfu coal and Sunflower stalk.The influence of catalyst on co-pyrolysis of Shenfu coal and Sunflower stalk wasinvestigated. And it is indicated that with Fe(NO3)3load on Shenfu pulverized coal byexcessive impregnation method, the tar yield can be improved, and also the greatsynergistic effect is appeared. Catalytic co-pyrolysis of Shenfu coal and Sunflower stalkunder H2atmosphere was studied, the results show that when adding6%Fe(NO3)3,mSFC:mSSat4:6, gas flow rate at60mL/min, temperature at600℃for1h, and heatingrate at10℃/min, the co-pyrolysis tar yield is29.98%, which is7.76%higher than thecalculated value. According to the XRD and GC-MS analysis of raw coal, catalyst andco-pyrolysis char, the result show that Fe(NO3)3is decomposition to iron oxides andnitrogen oxides under high temperature. Iron oxide can cause more H free radicalsdissociate from H2and biomass, so it can improve the tar yield from co-pyrolysis ofShenfu coal and Sunflower stalk, and make the synergistic effect of co-pyrolysis.