Raney nickel promoters

P. Gallezot, P.J. Cerino, B. Blanc, G. Fleche and P. Fuertes, Glucose Hydrogenation on Promoted Raney-Nickel Catalysts, Journal of Catalysis 146 (1994) 93. 

Source Compiled from S.R. Montgomery, Functional group activity of promoted Raney nickel catalysts, in Catalysis of Organic Reactions, W.R. Moser, Ed., Marcel Dekker, New York, 1981, pp. 383-409. 

Compounds 3 (when R=He) and 5 are available In commercial quantities. Compound 4 may also be purchased or prepared In high yield via hydrogenation of 3 over a promoted Raney nickel catalyst (C. 6. Coe, unpublished results). The condensation of 4 with distilled acryloyl chloride proceeds In over 95X yield. 

Aqueous phase reforming of glycerol in several studies by Dumesic and co-workers has been reported [270, 275, 277, 282, 289, 292, 294, 319]. The first catalysts that they reported were platinum-based materials which operate at relatively moderate temperatures (220-280 °C) and pressures that prevent steam formation. Catalyst performances are stable for a long period. The gas stream contains low levels of CO, while the major reaction intermediates detected in the liquid phase include ethanol, 1,2-pro-panediol, methanol, 1-propanol, propionic acid, acetone, propionaldehyde and lactic acid. Novel tin-promoted Raney nickel catalysts were subsequently developed. The catalytic performance of these non-precious metal catalysts is comparable to that of more costly platinum-based systems for the production of hydrogen from glycerol. 

Selective catalytic hydrogenation with chromium-promoted Raney nickel is reported (e.g. citral and citronellal to citronellol) NaHCr2(CO)io and KHFe(CO)4 reduction of a/3-unsaturated ketones (e.g. citral to citronellal) has been described (cf. Vol. 7, p. 7). The full paper on selective carbonyl reductions on alumina (Vol. 7, p. 7) has been published." Dehydrogenation of monoterpenoid alcohols over liquid-metal catalysts gives aldehydes and ketones in useful yields. ... 

The highest (iBu)2NH yield (72 %) was obtained a conversion level of 92% and at reaction parameters P=13 bar, T=240°C, WHSV=1.0 g/g h, NH3/iBuOH= 1.7, H2/NH3= 1.9. In conclusion, a secondary amine yield above 70 % can be was obtained in fixed bed reactor using vanadium promoted Raney nickel catalyst without recycling unconverted alcohol. In order to describe the conversion of alcohol, as well as the yield and selectivity of diisobutylamine in the function process parameters, experiments were carried out and results were evaluated according to orthogonal factorial design (6,7). 

This work has been undertaken to compare promoted Raney nickel catalysts... 

ACTIVITY AND STABILITY OF PROMOTED RANEY-NICKEL CATALYSTS IN GLUCOSE HYDROGENATION... 

It is well known, even from old literature data (ref. 1) that the presence of metal promotors like molybdenum and chromium in Raney-nickel catalysts increases their activity in hydrogenation reactions. Recently Court et al (ref. 2) reported that Mo, Or and Fe-promoted Raney-nickel catalysts are more active for glucose hydrogenation than unpromoted catalysts. However the effects of metal promotors on the catalytic activity after repeated recycling of the catalyst have not been studied so far. Indeed, catalysts used in industrial operation are recycled many times, stability is then an essential criterion for their selection. From a more fundamental standpoint, the various causes of Raney-nickel deactivation have not been established. This work was intended to address two essential questions pertinent to the stability of Raney-nickel in glucose hydrogenation namely what are the respective activity losses experienced by unpromoted or by molybdenum, chromium and iron-promoted catalysts after recycling and what are the causes for their deactivation ... 

Activation of Raney Ni by Other Metals. The promoting effect of various transition metals for Raney Ni has been the subject of a number of investigations and patents.62 Promoted Raney nickel catalysts may be prepared by two methods (1) a promoter metal is added during the preparation of the Ni-Al alloy, followed by... 

TABLE 1.6 Hydrogenation of Organic Compounds with Promoted Raney Nickel Catalysts with Optimum Activity3... 

An ESCA analysis of the molybdenum promoted Raney nickel showed that when a low molybdenum content alloy was used, the activated catalyst had greater amounts of nickel on the surface than the unpromoted active catalyst. At a 2% molybdenum content the nickel surface area in the activated catalyst reached a maximum and then decreased with the presence of more molybdenum. These findings correlate with the observed maximum in catalytic activity observed with the 2% molybdenum Raney nickel catalyst. The initial increase in... 

Hydrogenation experiments with simultaneous acoustic irradiation were carried out by using iso-propanol (2-propanol) as solvent in an automatic laboratory-scale autoclave (Parr 4560) with an effective liquid volume of 250 ml. The operating conditions were as follows 50 bar hydrogen pressure and 70°C (343 K) as the reaction temperature. The catalyst-to-citral ratio was 1 25 (wt wt) in the beginning of the reaction. A commercial molybdenum promoted Raney nickel catalyst with a mean particle size of approx. 22 pm and the specific surface area in the range of 80 m /g was used in the experiments. The reactor contents were analyzed oiF-line with gas chromatography (GC). 

In the presence of chromium promoted Raney nickel, citral can be hydrogenated to citronellol in yields in excess of 95% [12]. NiCria is amongst the most selective catalysts we prepared in the hydrogenation of citral to citronellal but the citronellol selectivity is low. However, chromium promoted Raney nickel has to be used in methanol in the presence of KOH in order to be selective [13], we did not carry out the reaction under these conditions. 

It is interesting to note that chromium ions have been used as promoters in Raney nickel based catalysts for the selective acetophenone reduction. The selectivity increase in the hydrogenation of the C=0 bond of acetophenone over both chromium ion promoted Raney nickel and Ru-Cr-B/Si02 catalysts was attributed to the strong interaction of the oxygen atom of the carbonyl with Cr ions. All these results suggest the formation of metal ion - metal nanocluster ensemble sites also in nickel-containing catalysts. 

Selective hydrogenation of aj unsaturated carbonyl contpoandsJ Several substrates of this type have been selectively hydrogenated to a, -unsaturated alcohols with catalysis by a chromium-promoted Raney nickel catalyst. ... 

In addition to the metal catalysts previously mentioned for the formation of H from aqueous-phase biomass-derived compounds, tin-promoted Raney-nickel catalysts also selectively generate H and alkanes similarly to Pt(3 wt catalysts... 

Citronellol can also be made by the selective hydrogenation of citral (55) and citronellal (135) using a chromium-promoted Raney nickel catalyst [171, 172]... 

Non-conjugated enones can be reduced to tbe corresponding unsaturated alcohols using a chromium-promoted Raney nickel catalyst in the presence of a strong inorganic base and methanol, provided that the carbonyl group is unhindered and the alkene unit is highly substituted, ... 

Gallezot P, Cerino PJ, Blanc B, Fleche G, Fuertes P. Glucose hydrogenation on promoted Raney-nickel catalysts. J Catal. 1994 146 93. 

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