Novas rotas redoxes para produção de gás de síntese a partir de gás natural ou glicerol

Abstract

The requirement for cleaner fuels associated with the demand for independence from non-renewable energy has promoted the development of process that convert any carbon source (X) in synthetic liquid (to liquid TL) (XTL processes). In this paper, we present a new technology for generation of syngas, an important feedstock to fuelproduction, using associated natural gas and residual glycerol from biodiesel industries. In Chapter 1 it is presented a general introduction about the XTL processes, as well as the main steps involved. The origin, problems and main alternatives for utilization of associated natural gas are shown. It was still exhibited the context of biodiesel industryand industrial generation of glycerol in Brazil. Finally, the technology developed in this work was presented. In Chapter 2, it was described the applied methodology. In Chapter 3, metal oxides based on Fe, Ni, Co or a combination of these metals supported on alumina were investigated as catalysts in carbon deposition/ oxidation processes, using CH4 as substrate for the chemical reaction. For the Fe-based catalysts, it stands out Fe10A material (10 wt.% of Fe2O3 in Al2O3), which led toformation of large quantities of syngas (0.5 mmol of H2 and 0.05 mmol of CO) and CH4 (0.03 mmol). Regarding the Ni catalysts serie, Ni10A (10 wt.% of NiO in Al2O3) showed higher catalytic activity, being able to generate 1.4 mmol of H2 and 0.2 mmol of CO during oxidation step. Among the Co-based materials, Co30A (30 wt.% of Co2O3 inAl2O3) showed the best performance in the carbon deposition step, detecting only H2 formation during oxidation. The addition of Co to the Fe catalyst, Co10Fe20A (10 wt.% of Co2O3 and 20 wt.% of Fe2O3 in Al2O3), improved the activity of this system in syngas generation (1.8 mmol of H2 and of CO). The Ni10Fe20A catalyst (10 wt.% of NiO and 20 wt.% of Fe2O3 in Al2O3) showed similar results to bimetallic system based on Fe and Co. Chapter 4 reports the use of iron oxides supported on the various matrices as catalysts in carbon deposition/oxidation process, using glycerol as substrate. For alumina support, there is an increase in the activity of the catalysts with metal addition, highlighting Fe30A material (30 wt.% of Fe2O3 in Al2O3), which is able to produce syngas at a H2:CO ratio of 1.9:1. The catalysts supported on bentonite configured asthe less active in reactions involving glycerol. For the systems supported on MCM-41, Fe30MCM (30 wt.% of Fe2O3 in MCM-41) showed higher activity, being capable to generate about 4 mmol of H2 and the same amount of CO.