Matti Reinikainen

Oxygenates from syngas over highly dispersed cobalt catalysts

Highly dispersed cobalt metal catalyst has been prepared by the deposition of Co2(CO)8 on silicagel in an oxygen-free condition and has been characterized with EXAFS. This catalyst exhibited high activity for the formation of C2+ oxygenates from syngas without any modification. The formation of hydrocarbons was strongly suppressed and the selectivity of oxygenates, especially C2-oxygenates, was enhanced by the modification with alkali or alkaline earth cations. From the modification effects on CO hydrogenation and by the studies of in situ FT-IR, these basic cations were considered to reduce the hydrogenating ability of the catalyst by controlling the electronic state of the active cobalt site. Noble metals such as iridium and ruthenium have little effect on the catalyst of CO hydrogenation. Similar cobalt catalysts were prepared from C02(CO)8 on other oxide supports and some oxides showed a similar effect on the basic additives. The effect of the cations and the reaction mechanism for the formation of oxygenates were discussed.

The effect of the precursor on the characteristics of Co/SiO2 catalysts

Abstract The effect of the precursor on the characteristics of the Co/SiO 2 catalysts prepared from Co(NO 3 ) 2 , Co 2 (CO) 8 and Co 4 (CO) 12 was determined. The near-surface reduction was clearly lower for the Co 2 (CO) 8 derived catalyst than for the Co 4 (CO) 12 based one. The hydrogen chemisorption, CO desorption, XRD and XPS measurements indicated that the dispersion of the metallic species decreased in the precursor order Co 2 (CO) 8 > Co 4 (CO) 12 ≫ Co(NO 3 ) 2 . The TPD studies showed that CO was more strongly adsorbed on catalysts derived from carbonyls than on those based on nitrate, resulting in greater initial activity in CO hydrogenation. In pulsed CO hydrogenation reactions, the selectivity of the Co 2 (CO) 8 derived catalyst differed from the other two. Thus, despite the well documented transformation of the Co 2 (CO) 8 to Co 4 (CO) 12 on the silica support, the supported catalysts derived from these two precursors exhibited distinct characteristics and reactivity.

CO hydrogenation activity of carbonyl cluster derived Co-RuSiO2 catalysts prepared by reflux method

Abstract The applicability of a reflux method for the preparation of cluster-derived CoRu catalysts supported on silica was studied. The properties of the resulting catalysts were compared with those of the corresponding catalysts prepared by impregnation. The presence of ruthenium either as a component of a bimetallic cluster or in a physical mixture of the two metals was essential for the adsorption of cobalt on silica. The activity and selectivity of these catalysts in CO hydrogenation were different from those obtained with catalysts prepared by impregnation.

Short Vapour Residence Time Catalytic Pyrolysis of Spruce Sawdust in a Bubbling Fluidized-Bed Reactor with HZSM-5 Catalysts

Catalytic pyrolysis of spruce sawdust was carried out in a bubbling fluidized-bed reactor using HZSM-5 catalysts. The effects of space velocity, catalyst deactivation, catalyst acidity and catalyst regeneration were studied. The use of catalysts decreased the yield of organic liquids compared to non-catalytic yields while the yields of pyrolytic water and gases increased. Decreasing the space velocity enhanced these effects. The rate of catalyst deactivation depended on the acidity of the catalyst, with more acidic catalysts deactivating more rapidly. Using a catalyst with a Si/Al ratio of 140 resulted in the largest changes in bio-oil properties. Periodic regeneration of the catalyst in the fluidized-bed reactor was also demonstrated using varying regeneration times and temperatures. It was shown that compared to BFB reactors, CFB reactor types would offer better operating characteristics for commercial scale catalytic pyrolysis processes in regard to vapour residence times, and catalyst activity and regeneration.

The effect of decomposition atmosphere on the activity and selectivity of the carbonyl cluster derived Co/SiO2 and Rh/SiO2 catalysts

Abstract The effect of pretreatment atmosphere, hydrogen or carbon monoxide, on the activity and selectivity of the Rh 4 (CO) 12 /SiO 2 and Co 4 (CO) 12 /SiO 2 catalysts in CO hydrogenation was determined. The catalysts pretreated under hydrogen exhibited a higher degree of decomposition of the original cluster, higher hydrogen uptake and lower carbon content than those decomposed under CO. Therefore, some of the active sites of the catalysts were encapsulated by carbon, and in the case of Co 4 (CO) 12 poorly reducible cobalt silicates were probably also formed. The activity of the hydrogen-treated Rh 4 (CO) 12 /SiO 2 was fairly similar to that of the CO-treated catalyst, but significantly fewer oxygenates were formed. Thus, the carbon monoxide treatment appeared to facilitate the formation of oxygenates. Probably the original structure of rhodium carbonyl was better retained, and thereby some of the rhodium particles remained more dispersed under CO than under hydrogen. In the case of Co 4 (CO) 12 /SiO 2 catalysts, however, no benefit was observed in conjunction with CO pretreatment either in activity or selectivity. Most likely the CO treatment resulted in the formation of unreactive carbonaceous species which permanently blocked most of the active sites.

Selective Vapor Phase Hydroformylation of Olefins Over Cluster-Derived Cobalt Catalysts Promoted by Alkaline Earth Oxides

Abstract Vapor phase hydroformylation of ethene and propene was studied with Co/SiO 2 catalysts. A selectivity of oxygenates of Co/SiO 2 derived from Co 2 (CO) 8 was markedly improved by the addition of alkaline earth oxides such as Ca, Sr, and Ba, although these additives decreased the activity of the catalyst. They also promoted the formation of propanoic acid and aldol condensates of propanal in ethene hydroformylation, and decreased the fraction of n-oxygenates in the total oxygenates in propene hydroformylation. EXAFS studies revealed that the active site for hydroformylation is a highly dispersed cobalt metal. Alkaline earth oxides promote to CO insertion to surface alkyl species by enhancing the interaction between CO and Co metal.

Reactions of synthesis gas on CoIr/SiO2 and CoRu/SiO2

The work on carbonyl based silica supported Co, CoIr and CoRu catalysts provided evidence for the synergistic effect of It or Ru addition; the CO uptake and the tolerance to air-exposure increased, and the performance in CO hydrogenation was significantly altered.