Gerald Grunewald

Oxidative dehydrogenation of ethylbenzene to stykene over carbon-based catalysts

Abstract Catalysts based on pyrolyzed polymeric systems and high surface area carbons have been investigated for their activity in the oxidative dehydrogenation of ethylbenzene to styrene. A relationship between surface area and activity is established, with high surface area materials displaying greater activity. One material in particular, ultrahigh surface area carbon molecular sieves, exhibits extraordinary reactivity—80% conversion with over 90% selectivity to styrene in a single pass at 350 °C. This is more active than recently reported inorganic oxide-based catalysts at a significantly lower temperature. The results are consistent with the proposal that the carbonaceous overlayer observed in many inorganic oxide systems is the true catalyst, and that the surface structure of this carbon is the key to the catalytic activity.

Preparation characterization, and reactivity of a novel heterogeneous catalyst for the reduction of CO and CO2

Abstract A heterogeneous catalyst consisting of Ru 3 (CCO) 12 supported on pyrolyzed polyacrylonitrile (PPAN) has been employed in the reduction of CO and in the methanation of CO 2 . This novel support was chosen because its structural characteristics could provide stronger binding sites for heavy metal clusters than the more typical inorganic oxide supports. Characterization of PPAN is studied and a pyrolysis profile which maximizes the formation of fused pyridine rings is proposed. A comparison between 2% Ru/PPAN and 2% Ru/Al 2 O 3 shows a significantly different product distribution, with the former having improved selectivity for small molecular weight products. The new catalyst also shows pronounced activity in the hydrogenation of CO 2 to CH 4 . A mechanistic study using aldehydes in addition to syngas suggests that both CO dissociation and CO insertion occur in the homologation mechanism.

Physical studies of MoO3 catalysts on silica and carbon supports

The nature and characteristics of the catalytic surface of supported MoO3 catalysts were studied. Changes that occurred on oxidizing alcohols in air over carbon and silica supported MoO3 were examined. Structural data were combined with electron microscopy and photoelectron spectroscopy to demonstrate that the carbon support promotes segregation and fragmentation of MoO3, whereas sintering occurs on silica. Results indicated that this may be correlated with a synergism between the carbonaceous material and metal oxide which provides a reoxidation pathway for reduced Mo, thus preventing formation of extended zones of MoO2, which is inactive for the oxidation of alcohols.

Reduction of carbon monoxide and dioxide by metal carbonyls on a pyrolysed polymeric support

A heterogeneous catalyst consisting of Ru3(CO)12 supported on pyrolysed polyacrylonitrile (PPAN) has been employed in the Fischer–Tropsch reaction and in the methanation of CO2; a comparison between 2% Ru/PPAN and 2% Ru/Al2O3 shows a significantly different product distribution, with the former having improved selectivity for small molecular weight products.