Oxidative dehydrogenation reaction of short alkanes on nanostructured carbon catalysts: a computational account.

ABSTRACT

Recent progress from first principles computational studies is presented for catalytic properties of nanostructured carbon catalysts in the oxidative dehydrogenation (ODH) reaction of short alkanes. Firstly, a brief introduction is given on the development of carbon catalysts in ODH since 1970. Oxygen functional groups have pivotal importance for ODH on nanostructured carbon catalysts. We discuss the oxidation process by HNO3 on pristine and defective carbon materials. The interactions between the oxygen molecule (oxidant) and the nanostructured carbon catalysts are quantitatively calibrated. Moreover the different nucleophilic abilities of oxygen functional groups are carefully compared and the strongest nucleophilic sites are proposed. The active sites and detailed reaction pathway are revealed from several computational studies. Diketone/quinone groups are generally considered to be the active centers in ODH. A reaction pathway via radical formation is considered as the favorable path. Furthermore, single ketone and carbon sites are verified to be active in ODH from the analysis of aromaticity. Heteroatom doping effects in ODH are examined. Nitrogen doping is found to be very reactive towards oxygen molecule activation. Other dopants such as boron, phosphorous and sulfur also have positive effects on the reactivity of ODH. Extensive calculations suggest that the BEP relation is applicable for the doped nanostructured carbon catalysts. In the end, an outlook for the future direction of the computational study is supplied.