Catalisadores baseados em óxido de nióbio e suas aplicações em reações da cadeia de combustíveis

Abstract

Actual society is extremely dependent on fossil fuels that are widely used to drive engines, heat materials and produce energy. Although these fuels have several aspects that go against sustainability (such as the fact that they are not renewable and provide damage to the environment) the planetary energy matrix is still heavily dependent on fossil fuels, and world energy dependence, compounded by the progressive shortage of oil, motivates research to try to solve or minimize these problems. In this work, were prepared catalysts from commercial hydrated niobium oxide (HY-340), kindly granted by the Brazilian Mining and Metallurgy Company (CBMM), which was sulfated with sulfuric acid and p-toluenesulfonic acid. These materials were characterized by adsorption/desorption of N2, infrared spectroscopy, Raman spectroscopy, X-ray diffractometry (XRD), acid sites determination by pyridine adsorption and reduction at programmed temperature (TPR). The materials were used as catalysts in three different reactions: (i) direct methanol oxidation to dimethoxymethane (DMM) production which is used as an additive for diesel, (ii) oleic acid esterification for the biodiesel production and (iii) quinoline oxidation, an important nitrogenated contaminant present in liquid fuels obtained from petroleum. In the methanol oxidation reaction, the niobium oxide materials showed conversions of up to 90% and selectivity to the dimethoxymethane (DMM) of almost 100%, at the temperature of 100 °C and 5 hours of reaction. The performance of the materials in the oleic acid esterification promoted 92% conversion after 4 hours of reaction. Finally, the sulfated materials were able to remove 55% quinolone by advanced oxidation process. Modifying niobium catalysts through sulfation has led to the creation of a versatile material that offers numerous possibilities and multiple applications in fuel chain reactions. In addition, heterogeneous catalysts have some advantages since the catalyst is more easily separated from the reaction medium, reducing corrosion and wastewater treatment problems.