Effect Of Graphitic Structure And Surface Properties Of Carbon Materials On Catalytic Performance Of Their Supported Metal Catalysts

Carbon supported noble metal catalysts were widely used in the field of chemical industry. The physical structure (skeleton structure) and surface chemical properties of carbon materials have an important impact on the dispersion and structure of supported metal nanoparticles. The present paper studied on the skeleton structure and surface modification of carbon materials, to investigate the influence of skeleton structure and surface modification on the supported metal catalysts. The main results are as the followings:1. High surface graphitic carbon (HSGC) was prepared via mechanical ball-milling method. The influence of ball-milling time, the number of iron balls and rotation speed of ball-milling process on the graphitic degree and pore structure of HSGC were studied. The influence of surface area and graphitic structure of support on the catalytic performance of Ru/HSGC catalysts were studied. The results reveal that the Ru dispersion increases with the decrease of graphitic degree of support; the catalytic performance is independent of surface area when the specific surface area surpasses350m2·g-1; meanwhile, the performance of Ru-based ammonia synthesis reaction increases with the increase of the graphitic degree of support.2. High surface graphitic carbon supports were modified by surface oxidation and nitrogen-doping, respectively, and the influence of surface modification on the activity of Ba-Ru-K/HSGC catalysts for ammonia synthesis was studied. The results indicate that surface oxidation results in a decrease of the catalytic performance of Ba-Ru-K/HSGC ammonia synthesis catalysts, and nitrogen modification of high surface graphitic carbon no longer has influence on the catalytic performance of the catalysts. Meanwhile, the effect of nitrogen-doped support on the catalytic performance of Au/HSGC catalysts in acetylene hydrochlorination was studied. The results show that the initial activity and stability can increase after the nitrogen modification of HSGC.3. The amount of surface acid groups of activated carbon was modified by several oxidation methods. The effect of surface acid groups on the catalytic performance for Ru/AC catalysts in benzene hydrogenation and Ba-Ru-K/AC catalysts in ammonia synthesis were studied, respectively. The results reveal that when the surface acid groups are in the range of from0to2.6mmol·g-1, the activity of benzene hydrogenation increases with the increase of surface groups, however, the performance of ammonia synthesis first increases to a peak and then decreases. This is probably ascribed to that the increase of surface acidity is good for adsorbing the π bond of benzene in benzene hydrogenation, but which is bad for ammonia dissociation in ammonia synthesis.