"Fast pyrolysis of elephant grass under different reactive atmospheres and upgrading of the resulting bio-oil."
Pyrolysis, bio-oil, elephant grass, fluidized bed, reactive atmosphere, HZSM-5, deoxygenation.
In recent years, due to the progressive depletion of conventional fossil fuels, renewable energy sources have played an important role in the energy matrix. Among these sources, the lignocellulosic biomass appears as a viable option, available and relatively easy to grow, without competing with food production. Pyrolysis stands as a route of transformation of biomass into products of different phases (gas, bio-oil, coal and condensed pyrolytic) with various applications. In this work, bio-oil is produced from elephant-grass (Pennisetum purpureum Schumach) in 1.5 and 40 kg/h fluidized bed reactors under different atmospheres (air, N2 and gas recycled from pyrolysis itself) at a temperature of 500°C. In the 1.5 kg/h bed, we carried out with and and without the HZSM-5 catalyst, both under N2. Pyrolysis without catalyst was also conducted with recycle (43, 74 and 85%) of gases. In the 40 kg/h bed, we conducted experiments under moderate oxidative atmosphere of air (71% N2 and 21% O2) varying the configurations of a gas-washing column (no heat exchanger with simple heat exchanger, with multi-pass heat exchanger) and the condensate recirculation (light products) product of pyrolysis reaction. Finally, the bio-oil obtained from experiments with recycle gas in the bed of 1.5 kg were subjected to deoxygenation mud bed of 5% Pt/C. The results showed that the recycle of gases caused a 53.96% increase in carbon in the pyrolysis common to the pyrolysis 70.89% 74% 77.16% recycle and pyrolysis with HZMS-5. The oxygen content decreased from 39.64% to 21.76%. The high heating value (HHV) increased from 26.1 to 33.11 MJ/kg. mass balance showed that 5.4 to 6.15% of the biomass is converted to CH4, C2H4, C2H6 and C3H8 pyrolysis with recycling of gases. Regarding the liquid phase all samples of bio-oils obtained were rich in phenols, especially those obtained in the oxidative atmosphere. The other components and majority functional groups are acetic acid, acetol, sugars and ketones. Based on the biomass of the mass of dynamic data in time a kinetic model of the parallel type (biomass producing bio-oil + condensate, coal and gas) was proposed whose ordinary differential equations were solved by Scilab v5.2 software to estimate kinetic constants