The influence of surface functionality on the activity of carbon-supported catalysts

Abstract

The aim of this research is to investigate how the presence of surface functional groups can influence the activity of carbon-supported MoS2 catalysts for coal asphaltene hydrogenation.Porous carbons were subjected to various chemical treatments in order to introduce oxygen and nitrogen surface functionalities prior to impregnation with ammonium tetrathiomolybdate.Supports and catalysts were examined by FTIR. Preoxidation of polymer-derived carbons lowered catalyst activity whereas preoxidation of a carbon black composite support increased it. Similar mixed results have been reported in the literature. The modified catalytic activity cannot be unequivocally attributed to surface oxygen. Qualitatively, it is considered that these groups exert some influence, but it is the structure of the carbon which is ultimately the controlling factor. In some cases, oxidation may introduce sites which promote interaction with metal species and, in others, oxidation may modify or destroy favourable sites which are already extant.Prenitriding was found to have a distinct influence in enhancing catalyst activity. The presence of nitrogen-containing surface groups may provide preferential sites for the adsorption of MO species.

Loading of Cobalt on Carbon Nanofibers

“…These observations illustrate an interaction of the metal with the surface carboxylic and phenolic groups. Interaction between the precipitated cobalt with the aromatic ring substituents or conjugated double bonds on the carbon surface is highly likely and this interaction has also been proposed by others (7,8). …”

The deposition of metal nanoparticles on carbon surfaces: the role of specific functional groups

“…Carbon as a support for heterogeneous catalyst nanoparticles is particularly challenging in this respect because of the complex surfaces that it can exhibit and because of the ability to change the nature of the surface with different surface treatments. An insightful study by Derbyshire et al highlighted this issue in 1986, 1 and it was later reviewed by Radovic 2 who emphasised its importance to catalysis. A recent study of ruthenium deposition on activated carbon is a good example of the complex behaviour that can take place.…”

Catalytic carbon membranes for hydrogen production

“…Derbyshire et al (1986) studied the effect of functional groups on the carbon surface on the catalytic activity of the carbon-supported molybdenum hydrodesulfurization catalysts. In their studies, functional O and N groups were incorporated by either partially oxidizing or nitriding the carbon surface.…”