Value Addition Of Carbon Dioixde For Commercially Important Products

Abstract

The mitigation of emissions of greenhouse gases, particularly carbon dioxide (CO2), and their effective utilization at present to the world is a difficult challenge and a major opportunity for sustainable development. Utilization of CO2 is important because of its significance and continuous rise in atmospheric CO2 concentration. CO2 is not just a greenhouse gas, but also an abundant, inexpensive, nontoxic, nonflammable, economical and biorenewable source, therefore, many possibilities for CO2 as a safe and cheap C1 component to produce useful compounds such as organic chemicals, materials, carbohydrates (e.g., foods) and fuels. Dimethyl carbonate (DMC) is very attractive chemical compound due to its versatile chemical reactivity and unique physical properties. As it can be used in terms of a non-toxic substitute for dimethyl sulfate and phosgene, which are toxic and corrosive methylating or carbonylating agents, also it is considered to be an option for meeting the oxygenate specifications for transportation fuels, green solvent and important intermediate for polycarbonate resins and polyurathenes. In contrast, utilization of carbon dioxide as the raw material for the synthesis of DMC has been attempted with solid base catalysts like hydrotalcite of varied molar ratio from 1.5 to 3.5 and ion exchanged zeolite samples. The hydrotalcite and ion exchanged zeolite samples were synthesized and characterized by the various spectroscopic techniques such as, P-XRD analysis, FT-IR spectroscopy, thermogravimetric analysis, scanning electron microscopy and surface area measurements. Among all the studied catalysts, the best conversion of propylene oxide (99.3%) with 8.2% selectivity of dimethyl carbonate and 52.3% selectivity of propylene carbonate was found over activated hydrotalcite of Mg/Al molar ratio of 1.5 as a catalyst at optimum reaction conditions one-pot synthesis of dimethyl carbonate. The effects of reaction parameters, such as amount of catalyst, temperature, partial pressure of CO2, reaction time and concentration of methanol on the selectivity dimethyl carbonate and propylene carbonate were studied in detail. Key words: Carbon dioxide; Sustainable development; Utilization; Energy; Emissions; Catalysis; Dimethyl carbonate; Fuels.