Study On The Pyrolysis Behavior Of Cotton Seed And Corncob When Adding Several Additives During Pyrolysis

This paper chooses cotton seed (CS) and corncob(CB) as rawmaterials for experiment and investigates the pyrolysis behavior ofbiomass with additives. Furthermore, scanning electronmicroscope (SEM) analysis, elemental analysis, the ash contentdetermination, the infrared spectroscopic (IR) analysis,1H NMRanalysis, temperature-programmed desorption, GC-MS and gaschromatographic analysis were carried out for the pyrolyzationproduct characterization, and then reveals the mechanism. Themain conclusions are as follows:1. Pyrolysis behavior of biomass with chloride and Ca–substratematerials.(1) The change trends of influence of temperature, residencetime or gas flow rate on product yield of cotton seed and corncobduring pyrolysis are basically the same; Investigation within thescope of the condition of the experiment, when the temperature is500℃, the residence time of30min, gas flow rate of100ml/min, the pyrolytic liquid oil yield is highest.(2) It is found that adding chlorides and Ca–substrate materialscan improve the liquid oil yield except CoCl2during pyrolysis ofcotton seeds, and the effect of the alkaline earth metal is superiorto that of alkali metal; liquid oil yield increases more obviouslywhen adding CaCl2, BaCl2and ZnCl2. Adding CaCl2, BaCl2and ZnCl2also can improve the yield of liquid oil during corncob pyrolysis.(3) During the process of biomass pyrolysis, lower temperaturecould generate more CO and CO2, medium temperature mainlyproduce CH4, while higher temperature mainly produced H2.2. Pyrolysis behavior of biomass with compound additives.(1) Under the following condition: pyrolysis temperature was500℃, N2flow rate was200ml/min and the residence time was30min, When adding15%of the mineral into the corncob, one couldfound that adding γ-Al2O3and M can improve the yield of liquid oilduring corncob pyrolysis, and the catalytic effect of γ-Al2O3issuperior to that of M, while adding HZSM-5and T made the oil yieldchange slightly.(2) Under the following condition: pyrolysis temperature was500℃, N2flow rate was200ml/min，the residence time was30minand the amount of the composite additive is15%, addingCaCl2/γ-Al2O3almost has no synergistic effect for oil yield during the pyrolysis of corncob; moreover, when the amount of CaCl2loading is10%, adding CaCl2/HZSM-5and CaCl2/M has obvious synergisticeffect for the oil yield, adding CaCl2/T also could improve the oilyield.(3) Under the following condition: pyrolysis temperature was500℃, N2flow rate was200ml/min，the residence time was30minand the amount of the composite additive was15%, when addingBaCl2/M, CaCl2/M and ZnCl2/M respectively during corncobpyrolysis, one could found that medical stone had synergism withBaCl2and CaCl2and had no synergism with ZnCl2for oil yield. Whenadding Ni (NO3)2/M and Fe (NO3)3/M, the oil yield decreased, whichindicating that there was no synergism between these two nitratesand medical stone.3. Analysis of the products(1) Adding the additives all coud make the Infrared absorptionpeak become stroger except COCl2, which implied that adding theseadditives all could prohibit the decomposition of hydrocarbons,alcohols, ethers and esters during biomass pyrolysis, so the residuecontains more organic compounds.(2) The content of aliphatic hydrogen decreased firstly and thenincreased with increasing of temperature; the content of aliphatichydrogen of oil obtained at500℃was the lowest, whie that of oil obtained at600℃is the lowest; While for the aromatic hydrogen,the content of aromatic hydrogen of oil obtained at500℃is equal tothat obtained at300℃, and they are all higher than that obtained at600℃.(3) During the pyrolysis of corncob, adding chlorides couldmake the content of aliphatic hydrogen and aromatic hydrogendecrease, while made the hydroxyl hydrogen increase; addingHZSM-5and medical stone made the content of aliphatic hydrogenincrease, and the hydroxyl hydrogen decrease, while when addingγ-Al2O3and medical stone, it is opposite. When adding medicalstone based chlorides, the content of different hydrogen changedslightly, while when adding medical stone based nitrates, thecontent of α hydrogen increased obviously, and then cause thecontent of aliphatic hydrogen increase.