The new pathway for methanol synthesis: Generation of methyl radicals from alkanes

The proposed scheme for methane oxidation to methanol in a vapor–gas system: CH4+12O2+(hv/HNO3)→CH3OH under mild conditions: at a temperature (T = 100 °C), atmospheric pressure (P = 1 atm), ultraviolet radiation of HNO3 (λ > 230 nm), and autocatalytic influence of nitric acid was investigated. In this way, methanol with 90% selectivity can be achieved at a methane conversion level of 10%. Quantum chemical calculations for the activation reaction of methane by hydroxyl radical (via HNO3 photo-dissociation) were performed using the density functional theory (DFT) method at the B3LYP/6-311++G(3df,3pd) level. Results of the DFT calculations which are broadly consistent with the experimental data, clearly find physicochemical justification. By and large, a possible extension of the technique here in, for the oxidation of higher alkanes (instead of methane) to methanol, in principle, also enhances the opportunity to recycle nitric acid, and the valuable semi-products (alkene and/or oxide of alkene).