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

Abstract

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.