Vapor phase catalytic hydrogenation

Manufacture. Tetrahydrofurfuryl alcohol is produced commercially by the vapor-phase catalytic hydrogenation of furfuryl alcohol. Liquid phase reduction is also possible. 

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... 

The vapor-phase catalytic replacement of chlorine by fluorine with hydrogen fluoride as the fluorine source has been the subject of a number of patents for the synthesis of Freons or Genetrons This topic has been carefully reviewed in the literature [2, p 97ff] One advantage of using a catalyst with hydrogen fluoride is to allow some degree of selectivity in the displacement of a specific chlorine from... 

Continuous vapor-phase catalytic hydrogenation of nitrobenzene, either fixed-bed or fluidized-bed, was originally developed by American firms in the 1950s, particularly American Cyanamid, encouraged by studies carried out at I.G. Farben during World War... 

The vapor-phase catalytic dehydrogenation of ethanol to acetaldehyde involves the diffusion of ethanol to the catalyst surface where it reacts to produce acetaldehyde and hydrogen. Under typical reactor conditions (temperature = 548 K, pressure = 101.3 kPa) the binary diffusivities of the three binary pairs encountered are... 

Figure I. Vapor-phase catalytic dehydrogenation and hydrogenation apparatus...

This study focuses on the vapor-phase catalytic hydrogenation of acetylene to ethylene and ethane ... 

Catalytic hydrogenation of furan to tetrahydrofuran is accompHshed in either Hquid or vapor phase. Hydrogenation of the double bonds is essentially quantitative over nickel catalysts but is generally accompanied by hydrogenolysis over the noble metals. 

Tetrahydronaphthalene is produced by the catalytic treatment of naphthalene with hydrogen. Various processes have been used, eg, vapor-phase reactions at 101.3 kPa (1 atm) as well as higher pressure Hquid-phase hydrogenation where the conditions are dependent upon the particular catalyst used. Nickel or modified nickel catalysts generally are used commercially however, they are sensitive to sulfur, and only naphthalene that has very low sulfur levels can be used. Thus many naphthalene producers purify their product to remove the thionaphthene, which is the principal sulfur compound present. Sodium treatment and catalytic hydrodesulfuri2ation processes have been used for the removal of sulfur from naphthalene the latter treatment is preferred because of the ha2ardous nature of sodium treatment. 

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

Catalytic hydrogenations can be carried out ia the vapor phase or ia the Hquid phase, either with or without the use of a solvent. The vapor phase reaction is limited to compounds which are thermally stable and relatively volatile. High boiling compounds and those which are thermally unstable must be hydrogenated ia the Hquid phase. 

In the petroleum (qv) industry hydrogen bromide can serve as an alkylation catalyst. It is claimed as a catalyst in the controlled oxidation of aHphatic and ahcycHc hydrocarbons to ketones, acids, and peroxides (7,8). AppHcations of HBr with NH Br (9) or with H2S and HCl (10) as promoters for the dehydrogenation of butene to butadiene have been described, and either HBr or HCl can be used in the vapor-phase ortho methylation of phenol with methanol over alumina (11). Various patents dealing with catalytic activity of HCl also cover the use of HBr. An important reaction of HBr in organic syntheses is the replacement of aHphatic chlorine by bromine in the presence of an aluminum catalyst (12). Small quantities of hydrobromic acid are employed in analytical chemistry. 

Hydrochlorination of Ethylene. The exothermic vapor-phase reaction between ethylene [74-85-1] and hydrogen chloride [7647-01-0] can be carried out at 130—250°C under a variety of catalytic conditions. Yields are reported to be greater than 90% of theoretical (14). 

Ethylamines. Mono-, di-, and triethylamines, produced by catalytic reaction of ethanol with ammonia (330), are a significant outlet for ethanol. The vapor-phase continuous process takes place at 1.38 MPa (13.6 atm) and 150—220°C over a nickel catalyst supported on alumina, siUca, or sihca—alumina. In this reductive amination under a hydrogen atmosphere, the ratio of the mono-, di-, and triethylamine product can be controlled by recycling the unwanted products. Other catalysts used include phosphoric acid and derivatives, copper and iron chlorides, sulfates, and oxides in the presence of acids or alkaline salts (331). Piperidine can be ethylated with ethanol in the presence of Raney nickel catalyst at 200°C and 10.3 MPa (102 atm), to give W-ethylpiperidine [766-09-6] (332). 

Oldenberg and Rase (13) have studied the catalytic vapor phase hydrogenation of pro-pionaldehyde over a commercially supported nickel catalyst. Their data indicate that the mathematical form of the reaction rate at very low conversions and 150 °C can be expressed quite well in the following manner. 

Oldenburg and Rase AIChE J., 3 (462), 1957] studied the catalytic vapor phase hydrogenation of propionaldehyde by making low conversion runs on a commercial supported... 

Aniline is an aromatic amine used in the manufacture of dyes, dye intermediates, rubber accelerators, and antioxidants. It has also been used as a solvent, in printing inks, and as an intermediate in the manufacture of pharmaceuticals, photographic developers, plastics, isocyanates, hydroquinones, herbicides, fungicides, and ion-exchange resins. It is produced commercially by catalytic vapor phase hydrogenation of nitrobenzene (Benya and Cornish 1994 HSDB 1996). Production of aniline oil was listed at approximately 1 billion pounds in 1993 (U.S. ITC 1994). Chemical and physical properties are listed in Table 1-2. 

Hydrar A catalytic process for hydrogenating benzene to cyclohexane. It is conducted in the vapor phase with a fixed-bed reactor. The catalysts are based on platinum and modified by lithium an alternative nickel-based catalyst is also used. Developed by UOP, subsequently renamed HB Unibon. 

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