Study of catalysts derived from chabazite for application in reactions of hydrogenation of CO2 to products

Abstract

CO2 from anthropogenic sources is the main cause of climate change. In the last 400,000 years, its concentration has varied but never exceeded 300 ppm. After industrialization, its concentration has risen sharply, having crossed the mark of 400 ppm. Recent studies show that the capture and use of carbon dioxide is the best alternative for mitigating its concentration in the atmosphere, as its conversion into fuels will not only help in minimizing the CO2 concentration, but will also provide an alternative source of energy and products. Two catalytic procedures have been studied. The first is production of synthesis gas (CO + H2) from CO2 for subsequent conversion to hydrocarbons via Fisher-Tropsch reaction. The second is the conversion into three steps: (1) hydrogenation of CO2 to methane, (2) conversion of methane to methanol, and (3) conversion of methanol to products. This second method is interesting because steps (2) and (3) could be integrated using bifunctional catalysts. In this context, this project has the objective of contributing to the conversion of methanol to olefins (ethylene and propene) using SAPO-34 micro/mesoporous catalysts. The reaction occurs with the formation of a "hydrocarbon pools", which have a kinetic diameter greater than the diameter of the pores of the SAPO-34 zeolites, and therefore only molecules of smaller diameter are able to outflow from the pores. Because of that, aromatic compounds are formed and retained inside the cavities, leading to the subsequent formation of coke and premature deactivation. The strategy used to minimize coke formation will be the use of SAPO-34 micro / mesopore catalysts, i.e. with two pore systems, prepared by desilication and desalumination procedures together with hydrothermal treatments. These strategies are expected to show improvements in mass transfer and decrease in coke formation rate compared to their traditional microporous counterparts.