Nanorod carbon nitride as a carbo catalyst for selective oxidation of hydrogen sulfide to sulfur

Two-dimensional mesoporous carbon nitride and its highly efficient nanorod framework were prepared via hard-templating method. The obtained materials were fully characterized. The results showed that the samples structural ordering and morphology were similar to those of the parent silica templates; they had large pore volumes as well as high surface area structures. Carbon nitride carbocatalysts were used for H₂S selective oxidation. The catalytic tests were carried out at 190, 210 and 230 °C in a fixed bed reactor. The obtained selectivity values for mesoporous carbon nitride rod and mesoporous carbon nitride toward elemental sulfur at 190 °C were 88.8% and 83%, respectively. Both samples were highly active due to their alkaline surface, appropriate pore size distribution and structure. In comparison with other carbon-based materials used for this process, mesoporous carbon nitride rod is the first carbonaceous material reported so far that could yield high levels of both conversion and selectivity at 190 °C. This superiority could be caused by the narrow pore size distribution (<3 nm), incorporation of nitrogen into the carbon matrix and its appropriate morphology. Nitrogen species act as electron donors in H₂S oxidation. Rod-like particles might have acted as nanoreactors that facilitated the reaction progress.