Phenol to cyclohexanone

Dutch State Mines (Stamicarbon). Vapor-phase, catalytic hydrogenation of phenol to cyclohexanone over palladium on alumina, Hcensed by Stamicarbon, the engineering subsidiary of DSM, gives a 95% yield at high conversion plus an additional 3% by dehydrogenation of coproduct cyclohexanol over a copper catalyst. Cyclohexane oxidation, an alternative route to cyclohexanone, is used in the United States and in Asia by DSM. A cyclohexane vapor-cloud explosion occurred in 1975 at a co-owned DSM plant in Flixborough, UK (12) the plant was rebuilt but later closed. In addition to the conventional Raschig process for hydroxylamine, DSM has developed a hydroxylamine phosphate—oxime (HPO) process for cyclohexanone oxime no by-product ammonium sulfate is produced. Catalytic ammonia oxidation is followed by absorption of NO in a buffered aqueous phosphoric acid... 

Because of the industrial magnitude of these processes, many catalysts have been examined with variations in metal distribution, pore size, and alkalinity. In most synthetic work where catalyst life and small variations in yield are not of great importance, most palladium-on-carbon or -on-alumina powder catalysts will be found satisfactory for conversion of phenols to cyclohexanones. Palladium has a relatively low tendency to reduce aliphatic ketones, and a sharp decrease in the rate of absorption occurs at about 2 mol of consumed hydrogen. Nickel may also be used but overhydrogenation is more apt to occur. 

Dodgson, I., Griffin, K., Barberis, G., Pignatari, F., Tauszik, G., A low cost phenol to cyclohexanone process, Chan. Industry (London), 24, 830-834,1989... 

Scire, S., Minico, S., and Crisafulli, C., Selective hydrogenation of phenol to cyclohexanone over supported Pd and Pd-Ca catalysts an investigation on the influence of different supports and Pd precursors. Appl Catalysis A-General 2002, 235 (1-2), 21-31. 

N.L. Basov and V.M. Gryaznov, Dehydrogenation of cyclohexanol and hydrogenation of phenol to cyclohexanon on membrane catalyst from palladium-ruthenium alloy. Membrane Catalysts Permeable to Hydrogen and Oxygen, Moscow, Topchiev Inst, of Petrochemical Synthesis, 1985, p. 117. 

An attractive property of Pd is its ability to catalyze the partial reduction of phenols to cyclohexanones. TWs is important industrially, and many adjustments have been made on the choice of carrier and promoter, to limit overhydrogenation. Palladium-on-BaCOj, palladium chloride-on-carbon, palladium-on-CaCOs, palladium-on-carbon, and pallad-ium-on-alumina ° have been used, but the last two generally are satisfactory. 

Hydrogenation of phenol to cyclohexanone Dense Pdj Pd93Ni7i Pd93Rii7 Pd7 Ag23... 

Figure 5.22 shows the flow diagram for catalytic hydrogenation of phenol to cyclohexanone. 

Narayanan et al. (512-516) and Chen et al. (517) investigated Pd-containing MgAl-oxide catalysts for the selective conversion of phenol to cyclohexanone at 180°C. The incorporation of Pd into the brucite-like layer of MgAl-COs-LDHs or impregnation of MgAl-COs-LDHs with PdCli enhances the catalytic performance in selectivity (>90%). 

The original preparation of cyclohexanone from phenol by hydrogenation to cyclohexanol followed by dehydrogenation has since been improved. Selective hydrogenation of phenol to cyclohexanone is possible using a palladium catalyst at 140°-170°C and 1-2 atm. An AlliedA ickers-Zimmer catalyst contained 0.5-5% palladium, supported on a low-surface-area calciiun aluminate which contained about 8-9% calcium oxide. ... 

Excellent synergy effect of Pd/C with solid Lewis acids exists in the hydrogenation of phenol to cyclohexanone with almost 100% selectivity under mild conditions. CO2 could enhance the apparent reaction rate, and the phase behavior influenced... 

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