Reforma a vapor do glicerol para a produção do hidrogênio como fonte alternativa de energia

Abstract

The depletion of fossil fuel reserves and the generation of atmospheric pollutants (NOx and SOx) from this resource has accelerated the development of alternative energy sources. In this scenario, Biodiesel has emerged as one of the largest substitute for conventional Diesel, however its accelerated production also increased the quantity of glycerol. This material presents a low commercial value in the market and in large scale has become an environmental risk, as there are no specific legislation to its final disposal. Thus, the glycerol steam reforming process for hydrogen production emerge as an alternative energy source with potential to contribute to sustainable development. The catalytic reaction of the steam reforming of glycerol can stoichiometrically generate up to 7 moles of H2 and 3 moles of CO2 per mole of glycerol consumed. Therefore, the objective of this work is to present a study of the steam reforming reaction under the Ni/CeO2 catalyst at different temperatures. The catalyst was prepared using PVA (Polyvinyl alcohol), Mili-Q water, Cerium(III) nitrate hexahydrate (Ce(NO3)3.6H2O) and ammonium hydroxide (NH4OH) to followed be deposited over microchannel plates. In addition, catalytic tests were performed using temperatures of 400 and 600°C and feed rates of 0.1 to 0.8 mL / min. In the results, it was observed difficulties in the deposition of the active phase of the catalyst, which increased the percentage of Ni above 15%. For the experiments conducted at 400ºC the maximum reaction yield and productivity were 15.5% and 4,773x10-7 m³/s, respectively. In addition, for this temperature the product fractions indicated the domain of the water gas shift reactions (WGS) and formation of methane. To the temperature of 600ºC the yield and productivity ranged from 10.7% to 19% and 2.91x10-7 at 1.31x10-6 m³/s respectively, and the probable reactions identified were carbon formation, methane formation and WGS. Furthermore, it was also observed from the results the formation of coke over the catalyst, which totalize 0.0134g. Therefore, the results indicated that the temperature of 600ºC was the most promising in this work producing higher amount of H2. Besides that, WGS and methane formation reactions were observed at both temperatures and the low yield and productivity observed was attributed to higher percentage of Ni deposited over CeO2.