Nitric oxide global warming

Adipic acid is of considerable importance since it is a precursor to nylon and polyester, which are extensively used in many products. Between two and three million tonnes are produced worldwide each year. Currently, its main method of manufacture is a costly, multistep process involving concentrated nitric acid. Nitrous oxide is produced as a by-product in such quantities that they measurably contribute to global warming and ozone depletion [24], A cleaner alternative to this process is clearly highly desirable. 

Nitrous oxide (N2O) is an important greenhonse gas with a radiative forcing effect 310 times that of CO2 and a lifetime in the troposphere of approximately 120 years. Part of the N2O is converted to NO in the stratosphere, and so contributes to depletion of ozone. Nitric oxide (NO) is very reactive in the atmosphere and has a lifetime of only 1-10 days. It contribntes to acidification and to reactions leading to the formation of ozone in the troposphere, and so also to global warming. 

Globally, the oxides of nitrogen, NO (nitric oxide), NO2 (nitrogen oxide), and N2O (nitrous oxide), are key species involved in the chemistry of the troposphere and stratosphere. NO and N2O are produced mostly by microbial soil activity, whereas biomass burning is also an important source of NO. Nitric oxide is a species involved in the photochemical production of ozone in the troposphere, is involved in the chemical produaion of nitric acid, and is an important component of acid precipitation. Nitrous oxide plays a key role in stratospheric ozone depletion and is an important greenhouse gas, with a global warming potential more than 200 times that of CO2. 

Methane (CH ) and nitrous oxide (N2O) are two important atmospheric components that contribute to global warming, besides carbon dioxide which is the major contributor. Both methane and nitrous oxide absorb infrared radiation, while nitrous oxide is photochemically oxidized to nitric oxide (NO) resulting in ozone depletion in the stratosphere. The nitric oxide formed also governs the concentration of other greenhouse gases. The amount of nitrous oxide and methane in the atmosphere has been continuously increasing since industrialization, with current increase rates of 0.25 and 1.2% per year, respectively. 

Adipinic acid is produced industrially by oxidation of cyclohexane in a multistep oxidation process with cyclohexanol/cyclohexanone as important intermediates. The process operates at 125-165 °C and 8-15bar and uses 50-65% nitric acid as the oxidant. As coupling product of the oxidation dinitrogen oxide (N2O) is formed that has to be removed from the process flue gas due to its ozone layer depletion effect and its very high global warming potential (298 times that of CO2). The reaction is catalyzed by vanadium and copper salts and reaches product yields of 96%. 

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