Desenvolvimento de um reator de pirólise aquecido por micro-ondas para produção de bio óleo e bio carvão a partir de biomassa lignocelulósica

Abstract

In this work a pyrolysis system heated by microwave radiation was developed with the objective of producing bio oil and bio char using biomass of pine wood residue as raw material. For this purpose, a microwave oven was used, whose cavity was adapted to allocate the quartz reactor. The system was purged with Ar gas to keep the atmosphere inert. Pyrolysis reactor was initially heated with the aid of a SiC heating element. To condense the produced bio oil a heat exchanger immersed in ice bath was used. After that, the bio oil was collected in a round bottom bottle, and the gases were directed to a gas washer system. A thermocouple and digital controller were used for monitoring and controlling the temperature of the pyrolysis. After assembling the system, operational conditions of external heating of the inert gas, the pyrolysis time (10, 15 and 20 minutes of reaction) and temperature (500, 600 and 700 °C) were evaluated. The best yields were obtained with 500°C and total time of 10 minutes of pyrolysis, producing 65, 33 and 2% of bio oil, bio char, and bio gas, respectively. The bio products formed were characterized (water and acidity in the bio oil; structural composition and morphological analysis for the bio char) and compared with the products obtained from conventional pyrolysis. After the evaluation using SiC as a heating element (external to the pyrolysis reactor), a microwave absorbent material (bio coal and graphite) was evaluated directly in contact with the sample (inside the reactor). Both materials were used independently for finding the appropriate amount in relation to the sample mass (20 and 50% m/m of bio coal or 0.1, 0.5, 1, 5 and 20% m/m graphite) looking for the yields previously obtained with the optimizations with SiC.