Investigação do processo de pirólise e reforma a vapor catalítica em série de resíduos sólidos urbanos (RSU) para a produção de um gás rico em hidrogênio (H2)

Abstract

Municipal solid waste (MSW) is a potential raw materials for thermochemical conversion processes, and among these processes, pyrolysis and steam catalytic reforming in series (PRVCat) stands out. PRVCat involves the integration of two reactors in the same process unit, that is, an initial pyrolysis stage followed by a steam reforming stage of the condensable vapors (pyrolysis oil), with char and a hydrogen-rich gas as the main products. The development of hydrogen (H2) production technologies from MSW can help reduce problems associated with global warming and climate change, promoting sustainable development and helping to reduce CO2 emissions. This study aims to evaluate the potential of the pyrolysis and steam catalytic reforming in series (PRVCat) process of Municipal Solid Waste (MSW) for the production of char and a hydrogen-rich gas (H2). MSW samples were collected from a group of 32 municipalities located in the Northeastern region of the state of Rio Grande do Sul. The group of municipalities comprises a population of 959,709 inhabitants, with an average MSW generation of 643.61 t·day-1. The samples were separated based on their composition, being identified as A (organic fraction), B (polymeric fraction) and C (organic fraction plus polymeric fraction). The gravimetric composition showed that 88% of the collected sample is composed of organic waste, 10% of polymeric material waste and 2% of metals and glass. The pyrolysis experiments were conducted at a temperature of 500 °C and a heating rate of 10 °C min-1 in the pyrolysis stage, as well as at a temperature of 900 °C in the steam catalytic reforming stage. A commercial catalyst (Ni/Alumina) was used in the PRVCat experiments. The char generated was quantified, obtaining yields between 22-30%. The condensable vapors obtained in the MSW pyrolysis stage were evaluated (oily fraction), and the presence of olefins, paraffins, naphthenes, and aromatic compounds was identified. For sample C, which refers to what was present in the collection trucks (after removing the metal and glass fractions), it is observed that the gas yield increases from 0.35+0.16 Nm³·kgRSU-1 to 0.97+0.11 Nm³·kgRSU-1, with the steam reforming of the volatiles produced in the pyrolysis process. At the end of the process, the production of a hydrogen-rich gas is verified, assuming a volumetric fraction greater than 50% of the composition of the gas produced. The results obtained in this study demonstrate the adequate potential of PRVCat as a promising technology for the energy valorization of MSW. The production of a hydrogen-rich gas from waste, which would be destined for landfills, represents a significant advance in the search for sustainable solutions for solid waste management. [resumo fornecido pelo autor]