Palladium on alumina

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 depropanizer overhead, Cj and lighter feed is compressed to about 300 psi and then passed over a fixed bed of acetylene removal catalyst, generally palladium on alumina. Because of the very large amount of hydrogen contained in this stream, the operating conditions are critical to selectively hydrogenate the acetylene without degrading the valuable ethylene to ethane. 

Troublesome amounts of C and Q acetylenes are also produced in cracking. In the butadiene and isoprene recovery processes, the acetylenes in the feed are either hydrogenated, polymerized, or extracted and burned. Acetylene hydrogenation catalyst types include palladium on alumina, and some non-noble metals. 

An efficient catalyst for thermal isomenzations of halofluorocarbons [6, 7, 8, 9] IS prepared by treatment of alumina with dichlorodifluoromethane at 200-300 °C [9] or aluminum chloride with chlorofluorocarbons in the presence of metals [W] or palladium on alumina [II These catalysts are far more efficient than aluminum halides themselves (equations 1 and 2)... 

Rapoport s findings have been confirmed in the authors laboratory where the actions of carbon-supported catalysts (5% metal) derived from ruthenium, rhodium, palladium, osmium, iridium, and platinum, on pyridine, have been examined. At atmospheric pressure, at the boiling point of pyridine, and at a pyridine-to-catalyst ratio of 8 1, only palladium was active in bringing about the formation of 2,2 -bipyridine. It w as also found that different preparations of palladium-on-carbon varied widely in efficiency (yield 0.05-0.39 gm of 2,2 -bipyridine per gram of catalyst), but the factors responsible for this variation are not knowm. Palladium-on-alumina was found to be inferior to the carbon-supported preparations and gave only traces of bipyridine,... 

Supported platinum-palladium. This aspect of the study focused on the characterization of platinum and palladium on alumina. The analytical capability of STEM Is fully demonstrated In a problem of this type, because of the rapid manner In which crystallite composition can be analyzed. This study Is especially Interesting because of Che use of platinum and palladium combinations In automotive catalysis. 

P 21 ] Palladium on alumina was employed as catalyst [26]. Hydrogen and organic reactant were mixed in the micro mixer and fed to a Merck Superformance HPLC column of 100 mm length and 5 mm inner diameter, which was used as a hydrogenator. No further details are given in [67] or [26]. 

Last, McClain disclosed the gas phase hydroamination of ethylene and propene with NH3 over palladium on alumina (Eq. 4.4) [46]. 

The catalyst used throughout this study was a 1% w/w palladium on alumina supplied by Johnson Matthey. The support consisted of 0-alumina trilobes (S.A. 100 m g" ) and the catalyst was sized to < 250 p for all catalytic studies. The alkenes and alkynes (all Aldrich >99%) were used without further purification. No significant impurities were detected by GC. Gases (BOG, >99.99%) were used as received. 

Birch has made good use of oxidative decarboxylation in hydrofuroic acids (Section VI,B,2) but otherwise the direct removal of hydrogen from a hydrofuran is usually regarded as impracticable, and while the dismutation catalyzed by palladium on alumina at 180 C is interesting, it depends too much upon the substitution pattern to be sufficiently general18 ... 

SELOP C4 A process for upgrading the C4 petroleum fraction by selective catalytic hydrogenation. Different catalysts, containing palladium on alumina, are used for different feedstock compositions. Developed by BASF and used in its Antwerp plant since 1994. 

The crude enamine is dissolved in 450 ml. of ether, and the solution is transferred to a 1-1. three-necked flask equipped with a sealed stirrer, a 250-ml. dropping funnel, and a two-necked adapter fitted with a calcium chloride tube and a thermometer immersed in the solution. A solution of 71-76 g. (0.85-0.90 mole) (Note 5) of methyl propiolate (Caution Methyl propiolate is a severe lachrymator and should he handled only in the hood.) in 150 ml. of ether is added dropwise. During the addition the temperature of the mixture is maintained at 25-30° by periodic cooling of the reaction flask in a dry ice-acetone bath. When the addition is almost complete, a white solid begins to separate. The mixture is stirred at 25-30° for an additional hour, cooled to 0°, and filtered to remove the solid. This is dissolved in 700 ml. of 6% hydrochloric acid (Note 6), the acidic solution is warmed at 55-60° for 1 hour, and the mixture is cooled and extracted with two 100-ml. portions of ether. The ether is removed on a steam bath, and the residue of crude methyl 10-oxocyclodec-2-ene-l-carboxylate is dissolved in 300 ml. of methanol and hydrogenated over 5 g. of 5% palladium-on-alumina catalyst at 40 p.s.i. pressure and room temperature. 

The reaction between deuterium and 1-butyne, 2-butyne, 1,2-butadiene, and 1,3-butadiene, respectively, was conducted in a flow system at near ambient temperatures. The catalyst (0.03 wt % palladium on alumina) was prepared by impregnating hard alumina pellets with palladium chloride so that the metal was probably confined to an outer shell of each particle. 

Oxidation of CO in automobile exhaust Platinum or palladium on alumina... 

Schiith, C., and M. Reinhard, Hydrodechlorination and hydrogenation of aromatic compounds over palladium on alumina in hydrogen-saturated water , Appl. Catal. B Environ., 18, 215-221 (1998). 

G-41 A chromia-alumina catalyst, used for hydrodealkylation and dehydrogenation reactions G-S8 Palladium-on-alumina catalyst, for selective hydrogenation of acetylene in ethylene G-52 Approximately 33 wt % nickel cm a refractory oxide support, prereduced. Used for oxygen removal from hydrogen and inert gas streams... 

Tetrahydrofurfuryl alcohol reacts with ammonia to give a variety of nitrogen containing compounds depending on the conditions employed. Over a barium hydroxide-promoted skeletal nickel—aluminum catalyst, 2-tetrahydrofurfurylamine [4795-29-3] is produced (113—115). With palladium on alumina catalyst in the vapor phase (250—300°C), pyridine [110-86-1] is the principal product (116—117) pyridine also is formed using Zn and Cr based catalysts (118,119). At low pressure and 200°C over a reduced nickel catalyst, piperidine is obtained in good yield (120,121). 

As with platinum, the palladium-catalyzed oxidation of anomeric hydroxyl groups in aldoses is a rather selective process.84 The influence of pH in the Pd-catalyzed oxidation of glucose has been studied. It was observed that the gluconic acid formed, in its free form, reversibly inhibits the oxidation process in acidic media.85 The oxidation of D-glucose has been performed with palladium-on-alumina and with bismuth-containing palladium-on-charcoal in water.85 The selectivity in the air oxidation of... 

Figure 5. Transformation pathway of lindane to benzene. Reprinted from Applied Catalysis B Environmental, Vol. 18, Schtlth and Reinhard, Hydrodechlorination and Hydrogenation of Aromatic Compounds over Palladium on Alumina in Hydrogen-Saturated Water, pp. 219, Copyright 1998, with permission from Elsevier Science.

Acetylene hydrogenation. Selective hydrogenation of acetylene to ethylene is performed at 200°C over sulfided nickel catalysts or carbon-monoxide-poisoned palladium on alumina catalyst. Without the correct amount of poisoning, ethane would be the product. Continuous feed of sulfur or carbon monoxide must occur or too much hydrogen is chemisorbed on the catalyst surface. Complex control systems analyze the amount of acetylene in an ethylene cracker effluent and automatically adjust the poisoning level to prepare the catalyst surface for removing various quantities of acetylene with maximum selectivity. 

In all of this work there was little suggestion that the surface states of the palladium might behave differently from bulk states. Selwood (17) indicated that, from some sorption-magnetic susceptibility data for hydrogen sorbed on palladium which was finely dispersed on alumina gel, the ultimate sorption capacity was approximately at the ratio 2H/Pd. Trzebiatowsky and coworkers (25) deposited palladium on alumina gel in amounts ranging from 0.46 to 9.1% of gel weight. They found the palladium to be present in a normal crystal lattice structure, but its susceptibility was less than for the bulk metal. This suggested to the present authors that the first layer of palladium atoms laid down on the alumina gel underwent an interaction with the alumina, which has some of the properties of a semiconductor. Such behavior was definitely shown in this laboratory (22) in the studies on the sorption of NO by alumina gel. Much of this... 

Another interesting result is the high yield reached with palladium on alumina. Beside the desired product dmf, trimethylamine, N-methylformamide and traces of N,N-dimethylurea were identified by GC-MS. The utilization of such a stable and disposable catalyst could be interesting for developing the solvent-free hydrogenation of carbon dioxide on an industrial scale. 

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