Ni-Kieselguhr catalysts

Adkins and Covert hydrogenated benzyl alcohol using Ni-kieselguhr catalysts prepared by various procedures, but the best yield of cyclohexanemethanol was only... 

Kehoe and Butt [J. P. Kehoe and J. B. Butt, AIChE /., 18 (1972) 347] have reported the kinetics of benzene hydrogenation of a supported, partially reduced Ni/kieselguhr catalyst. In the presence of a large excess of hydrogen (90 percent) the reaction is pseudo-first-order at temperatures below 200°C with the rate given by ... 

CHa.CHa.CHg.OH mw 133.19, N 10.52%, no props given. It was obtd in a mixt of mono-, di- tris(hydroxypropyl)amine when 3-hydroxy-proprionitrile was treated with H in an autor clave in the presence of Ni-kieselguhr catalyst. The mixt can be separated by distillation (Refs 1 2). It forms a Hexachloroplatinate, 2C6H,BN02.H2PtCl6, dec 211-12°... 

The rate controlling step for reaction involves methane adsorption. Catalyst structure has a marked effect on the kinetics of the reaction. Thus, under certain conditions the rate of reaction over a Ni/Kieselguhr catalyst at 911 K is first order with respect to the partial pressure of CH4 and independent of H2O and product partial P, while for other nickel catalysts the rate depends on the partial P of H2O, H2, and CO. ... 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

For more effective and/or larger-scale hydrogenations, use of higher temperatures and pressures is advantageous as in an example shown in eq. 5.3.5 Supported nickel catalysts such as Ni-kieselguhr may also be useful at temperatures above 100°C (eq. 5.4).6... 

The hydrogenation of phenols may proceed more readily than other aromatic compounds under proper use of catalyst and conditions. Over Ni-kieselguhr, hydroxyben-zenes such as phenol, catechol, and resorcinol are hydrogenated rapidly at 120-150°C under high pressure. Usually, the yields of the corresponding cyclohexanols are quantitative except for resorcinol, which gave only a 90% yield of cyclohexane-1,3-diol.70 An example is shown in eq. 11.11 for the hydrogenation of phenol. 

Sasa prepared an effective nickel catalyst for the hydrogenation of phenol by decomposition of nickel formate in a high boiling solvent such as diphenyl ether and diphenyl. The catalyst thus prepared proved more active than Ni-kieselguhr in the hydrogenation phenol (eq. 11.12) and could be used repeatedly more than six times.71... 

Ni-kieselguhr. iV-Butylpiperidine was obtained in a 78.7% yield when pyridine was hydrogenated in butyl alcohol at 220°C and 8.8 MPa of initial hydrogen pressure (eq. 12.15).22 The reaction was also studied using Raney Ni and copper-chromium oxide as catalysts, resulting in somewhat lower yields of N-butylpiperidine.24... 

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