Effects of nickel catalyst composition on the rate and selectivity of carbon dioxide hydrogenation

The hydrogenation of carbon dioxide has been examined in relation to the activity of catalysts containing 1–10 wt.% nickel, particularly as affected by the method of making the catalyst. Studies have been done on how alkali additives affect the activity of a nickel-aluminum catalyst. Measurements have been done on thiophen poisoning in the hydrogenation of CO₂ on nickel catalysts. N. G. Chernyshevskii Saratov State University, Saratov State University Chemical Research Institute, 83 Astrakhanskaya ul., Saratov 410026, Russia. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 5, pp.311–316, September–October, 1999.     

Ag/SiO2: a novel catalyst with high activity and selectivity for hydrogenation of chloronitrobenzenes

Ag/SiO2 prepared by an in situ reduction method are found, for the first time, to be highly effective and recyclable catalysts for the selective hydrogenation of a range of chloronitrobenzes to their corresponding chloroanilines, which are of great potential as industrially viable and cheap novel catalysts for the production of chloroanilines.     

Controlled deactivation of a skeletal nickel catalyst with sodium silfide in liquid-phase hydrogenation reactions

The kinetics of the liquid-phase hydrogenation of sodium maleate on skeletal nickel catalysts subjected to controlled deactivation with sodium sulfide solutions was studied. The possibility of reactivating partially deactivated skeletal nickel was systematically studied for the first time, and it was found that its activity in liquid-phase hydrogenation reactions can be regulated by the introduction of a catalyst poison in small amounts into the system.     

Effect of ligands on the hydrogenation selectivity in the presence of rhenium catalysts

It has been established that the catalytic activity of rhenium oxohalide complexes with phosphorus- or sulfur-containing ligands in hydroganation of C₆–C₁₀ olefins, nitrobenzene and p-nitrotoluene is primarily determined by the original ligand to rhenium ion bond. Chain length of olefins does not affect their hydrogenation rate.

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- C₆–C₁₀, - - . .

     

Effect of bond energies of a catalyst with reacting atoms on the selectivity of CO hydrogenation over metals

In hydrogenation over metals (M)_j carbon monoxide is adsorbed as a molecule. C–O bond rupture in partially hydrogenated complex, MCHOH, leads to MO and MCH₂ and then to hydrocarbons, while transformation of MCHOH into MCH₂OH gives alcohols and other oxygen-containing compounds. Selectivity towards hydrocarbons increases with increasing energy of M–O bonds.

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(M) . C–O MCHOH MO MCH₂ — ; MCHOH MCH₂OH . M–O.