Selectivity Of Nickel Catalysts Research Articles

Catalytic activity and selectivity of Palladium and Nickel catalysts in hydrogenation reactions of nitro- and acetylene compounds

This paper presents the results of a study on the catalytic activity and selectivity of nickel and palladium catalysts in hydrogenation reactions of nitro- and acetylene compounds. It was shown that the activity and selectivity of nickel catalysts in the hydrogenation of phenylacetylene depend on the nature of modifying additives (Cu, Zn, Ti, Cr, Bi, Ti–Cu, Mn, Fe), and the activity and selectivity of palladium catalysts based on a polymer of metal complexes depends on the method of their preparation. It was found that for certain concentrations of the active phase of palladium (0.8 wt.%) and the polymer of potassium humate (1.0 wt.%.) in the catalyst, where palladium and the polymer were deposited on bauxite-094 together, the catalyst exhibits the greatest activity and selectivity when hydrogenating phenylacetylene and potassium orthonitrophenolate.

Influence of the Zn\u2013Al binary oxide composition on the physicochemical and catalytic properties of Ni catalysts in the oxy-steam reforming of methanol

This paper presents the catalytic properties of mono- and bimetallic nickel supported catalysts in the oxy-steam reforming of methanol. The physicochemical properties of the supported catalysts were studied by various techniques such as TPR, TPD-NH3, XRD and BET. A significant impact of palladium and the support composition on the activity and selectivity of nickel catalysts in OSRM was demonstrated. The highest activity in the oxy-steam reforming of methanol reaction among all nickel catalysts was shown by the 20% Ni/ZnO·Al2O3 (Zn:Al = 1:1) catalyst. The acidity results correlate well with the reactivity of the investigated catalysts. The most active monometallic system showed the highest total acidity and was the easiest to reduce compared to the rest of the investigated Ni catalysts. The effect of palladium on the reducibility and reactivity of the nickel supported catalyst was proven. The activity results carried out in the OSRM reaction showed that such catalytic material may be potentially applied in fuel cell technology.

Selective hydrogenation of sunflower oil over Ni catalysts

This work focuses on the influence of the support and the preparation method on the activity and selectivity of nickel catalysts in the hydrogenation of sunflower oil. Catalysts were prepared over silica and alumina supports following the incipient wetness impregnation and deposition-precipitation techniques. The activation process was followed by temperature-programmed reduction (TPR). Precipitation-deposition method allowed a stronger metal-support interaction than incipient wetness impregnation. A precipitation-deposition time of 14 h (which allowed a Ni loading of about 20wt%) was deemed as the most adequate from the standpoint of high specific surface area and strong Ni-support interaction. The selectivity to oleic acid was not affected by the preparation method, but it was significantly influenced by the type of support. In this regard, the catalysts prepared on silica are more active and produce less saturated fatty acids.

Hydrogenation of aromatic hydrocarbons on nickel catalysts modified with heteropolycompounds

Summary 1. The high activity and selectivity of nickel catalysts (1–4 wt.%) was established on γ -Al 2 O 3 modified with heteropolytungstates for hydrogenation of benzene and toluene. 2. High-temperature treatment at 500°–600°C was shown to be necessary for forming active and stable catalysts for hydrogenation. 3. Systems modified with heteropolytungstates containing Co and Ni were found to be the most active catalysts for benzene hydrogenation.

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: V. Electronic effects on methanation of CO and CO 2

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: V. Electronic effects on methanation of CO and CO 2

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: IV. Electronic effects on the selectivity in the hydrogenation of 1,3-butadiene

The hydrogenation of 1,3-butadiene was carried out over various unsupported Ni catalysts: nickel-boride, Raney-nickel, decomposed-nickel, nickel-phosphide, and nickel treated with H 2S. It was found that the butene distributions characteristic of the catalysts were explainable in terms of the electron density of Ni metal and the reaction mechanism proposed by Wells and co-workers. It is suggested that there are critical electron densities of Ni metal at which catalytic properties change significantly.

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: III. Electronic and catalytic properties of nickel catalysts

Various nickel catalysts (nickel-boride, nickel-phosphide, Raney-nickel, Urushibara-nickel, and decomposed-nickel) were investigated to examine the relationships between catalytic and electronic properties of nickel catalysts modified by component elements (boron, phosphorus, aluminum, and zinc) in the catalysts. Based on the X-ray photoelectron spectroscopic results, a parameter Δ q was tentatively proposed to characterize the electronic properties of the catalysts. The specific activity (activity per surface area of nickel metal) for hydrogenation reaction, the adsorption equilibrium constant of acetophenone, the resistivity against poisoning, and the characteristic selectivities in hydrogenation of 1,2-butylene oxide were found to be summarized in terms of the parameter Δ q. It is suggested that Δ q is a useful parameter to reflect the electronic properties of the nickel catalysts.

Surface state, catalytic activity and selectivity of nickel catalysts in hydrogenation reactions. Part 2;.—Surface characterization of Raney nickel and Urushibara nickel catalysts by X-ray photoelectron spectroscopy

The X-ray photoelectron spectroscopic study of Raney and Urushibara nickel catalysts activated under various conditions was undertaken to characterize the surface state of the catalysts including the catalysts' structure. Raney nickel catalys contain both oxidized and metallic aluminium in the activated phase. As for Urushibara nickel catalysts digested with acetic acid or sodium hydroxide, metallic and oxidized zinc were observed in the catalyst surface. Based on the X.p.s. peak intensities for the catalysts, the structure of Urushibara nickel catalysts was found to be that of a supported catalyst, whereas Raney nickel catalysts showed X.p.s. features consistent with those expected for skeletal nickel catalysts.

On hydrogenation and dehydrogenation catalysts. XI. Influence of the degree of reduction on the activity and selectivity of nickel catalysts in hydrogenations of alkines

On hydrogenation and dehydrogenation catalysts. XI. Influence of the degree of reduction on the activity and selectivity of nickel catalysts in hydrogenations of alkines