468387 Product Distribution and Kinetics of Hydropyrolysis of Agro Residues Via Py-GC/MS and Py-FT-IR
The biomass characteristics such as volatile matter, fixed carbon, ash content, elemental C, H, N, S and O, and heating value were evaluated using standard techniques. It is important o note that the biomasses investigated in this study vary mainly in ash composition, and follow the trend: rice straw (19%) > EFB (7.5%) > pine wood (0.7%). Fast pyrolysis and hydropyrolysis experiments were conducted in a Pyroprobe® 5200 pyrolyzer in trap mode. Approximately 0.5 mg of the agro residues were pyrolyzed at a heating rate of >10,000 oC/s to the preset temperature of 400-700 oC and held for 60 seconds in hydrogen atmosphere. The vapors were characterized using Agilent two-dimensional GC/MS. The effect of hydrogen pressure from 1 to 25 bar on pyrolysate composition was investigated, and compared with pyrolysate composition in presence of He environment at atmospheric pressure. Experiments were also conducted wherein the time evolution of key functional groups of the pyrolysates was analyzed using an online FT-IR spectrometer (Agilent Cary 660). A significant reduction in the formation of oxygenated organics, especially carboxylic acids, furan derivatives and phenolics, and a concomitant increase in the production of linear and aromatic hydrocarbons were observed during fast hydropyrolysis compared to normal fast pyrolysis of Indian rice straw, even at medium pressures of hydrogen. High temperatures slightly improved the yield of linear hydrocarbons, but greatly increased the yield of aromatics during hydropyrolysis. Py-FT-IR study revealed the time evolution of the pyrolysates, and the reaction completion time. The time taken for maximum production of oxygenates varied from 10-15 s at 500 oC, which was similar for all three biomass varieties. More interesting results on (a) the evolution of individual functional group vibrations, (b) product characterization, and (c) char formation, for different biomass varieties will be discussed during the presentation. The implications of the results on the quality of bio-oil and its properties will also be addressed.
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