Análise de inflamabilidade da oxidação direta do metano para metanol com O2 e CO2 sob a ótica do design inerentemente seguro

Abstract

The conversion of methane to methanol through chemical looping reactions represents a current challenge that involves several requirements to become economically viable. Recent research highlights the advantages of conducting oxidations with the use of mild oxidizing agents instead of strong ones; however, the literature tends to focus on the consequences for selectivity and reaction conversion, while lacking studies that address process safety. The objective of this work was to investigate the safety benefits of replacing molecular oxygen with carbon dioxide as the oxidizing agent in the direct oxidation of methane to methanol, under the framework of Inherent Safer Design principles. The flammability analysis was conducted theoretically using Le Chatelier’s Mixing Rule, a reliable method for the context of this study and one already applied under similar conditions in the literature. Based on this approach, the flammability limits of the reaction mixture were calculated for both O₂ and CO₂ as oxidizing agents, and their behavior was examined under variations in temperature, pressure, and composition. The calculations were performed using Python programming, and the results were graphically organized with the aid of Origin Pro software. Flammability diagrams were constructed to compare the flammable zones of reactions using O₂ and CO₂, as well as the theoretical influence of temperature and pressure on these hazardous regions. In addition to explosion risks, carbon monoxide emission levels were analyzed, and the CO emissions from oxidation reactions specifically employing carbon dioxide were compared against occupational legislation and safety standards. The findings of this study support the hypothesis that the oxidation process using CO₂ is inherently safer than the one using O₂. This conclusion is indicated by the absence of flammable zones for the reaction mixture oxidized by carbon dioxide, as well as by the effect of CO₂ on the flammability limits of methane in air. Such a substitution of oxidants could be integrated into the future industrial-scale application of a chemical looping reaction that is both safer and economically viable.