Catalytic activity, catalyst

Figure 3. Hydrogen TPD patterns observed on Figure 4. Amoimt of adsorbed H and a reduced RuS2 catalyst. catalytic activity (at 273K) versus the degree...

Catalysts Catalytic activity 10 molg rnin Selectivity toMA/% (Conversion %)... 

It is apparent that optimum utilization of raw materials, capital, and energy resources will influence the choice of catalyst. Catalytic activity alone is not a sufficient criterion. A hypothetical catalyst might be wonderfully active and selective at 25°C and one atmosphere, but it would be difficult to build an economical process around it. 

The reaction of catechol methylation by methanol in gas-phase over modified y-alumina was studied with the aim to correlate catalytic activity and selectivity to acid/base properties of the catalysts. Catalytic activity and selectivity towards guaiacol formation (0-alkylation) was found to increase with surface acidity. A 20-fold change in the O/C-methylation ratio was achieved by varying the catalyst acid/base properties, keeping constant the other reaction parameters. 

Cordonna et al. made similar observations for the oxidation of a number of hydrocarbons over bi-metallic platinum-palladium catalysts. Catalytic activity was found to increase markedly with increased platinum content, the most active catalyst had a Pt/Pd ratio of 4/1, in accordance with previous work by Skoglundh [34]. 

Substrate Catalyst Catalytic activity, mol H2 (g-atom Pd) s Selectivity, %... 

All alumina- and titania-pillared montmorillonite samples doped with vanadium contain immobilized vanadyl ions bound to the pillars. The mode of vanadyl attachment in alumina-pillared samples does not depend on the mode of preparation, while in titania-pillared samples it does. Certain degree of delocalization of the unpaired electron into ligands and increased in-plane Tt-covalent bonding is observed for vanadyl ions present in the co-pillared (V-Ti)-PILC samples. Catalytic testing in the reaction of m-xylene ammoxidation shows that doping with vanadium enhances nitrile formation on both series of catalysts. Catalytic activity depends on the mode of sample preparation. It is particularly high or the (V-Ti)-PILC co-pillared samples, despite the low level of doping with vanadium. A hypothesis is advanced that this effect is due to the unique character of vanadyl species present in these samples. 

Figure 2. Activity of 10 prepared from ClRh[P(C6H5)3]3 and 4 increase as a function of the extent of recycling of the catalyst. Catalytic activities were measured as initial rates at 100 °C in toluene or xylenes.

Therefore, it is generally considered that cesium exists in the state of CsOH in the ruthenium catalysts. Catalytic activity of Ru-Cs+/MgO (Cesium is in the forms of CS2O or CsOH) is very high, which is only inferior to Ru-K catalysts. This promoter is very stable even in the presence of steam. The activity can be adjusted by the addition of nitrate and depends on the surface area of catalyst. 

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