Hydrogenation Of Acetone Research Articles

The Solvent Effect on the Hydrogenation of Acetone with Raney Nickel

Raneyニッケルによるアセトンの液相水素化に対する溶媒効果について速度論的検討を行なった。メタノール溶媒の場合には,水素化初期速度はつぎのように表わされ,r=k8K1KAKHCAPH/[1+KACA(1+K1√KHPH)+√KHPH+KSCS]2 半水素化アセトンに2個目の解離吸着水素が付加する段階が律速であること,メタノールは単に反応物質と表面をとりあう吸着質としてのみふるまうことを結論した。 n-ヘキサン溶媒の場合も同様な結果が得られた。一方,エタノール,1-プロパノール,1-ブタノール,2-プロパノール,2-ブタノールを溶媒とした場合は,水素化初期速度はつぎのように表わされた。r=k5K1K2KACAPH/1+KACA(1+K1√KHPH+K1K2KHPH)+√KHPH+KSCS これから,アセトン-水素コンブレックスが2-プロパノールに変わる段階が律速であること。これらの溶媒は吸着質として働くうえに,活性点数を滅少させる触媒毒として働くことを結論した。吸着平衡定数K1K2KHの温度依存性から算出した水素の見かけの吸着熱(2.7kcal/mol)はメタノール以外のアルコール溶媒の種類に無関係であったことから,吸着水素の性質はアルコールの種類によらないと考えられる。

Catalytic activity of nickel-copper alloys in the hydrogenation of acetone

Catalytic activity of nickel-copper alloys in the hydrogenation of acetone

Activities of Supported Palladium Catalysts for Hydrogenation of Acetone and Benzene

Several kinds of supported palladium catalysts were prepared and their activities for the hydrogenation of acetone and benzene were investigated.For the hydrogenation of acetone, the catalysts containing molybdenum oxide as a promoter were found to be highly active. In case of benzene, satisfactory activity was effected by impregnating the supports with an acidic solution of palladium chloride without any promoter. Palladium on activated carbon catalyst prepared by this method showed an excellent activity when reduced with hydrogen at room temperature. Palladium supported on silica or alumina was very active when calcined at about 450°C in air before reduction. In some cases, an increase in activity was brought about by passing hydrogen chloride over the catalyst at temperatures above 250°C after reduction.

Poisoning Effect of Carbon Disulfide on the Liquid-phase Hydrogenation of Acetone over a Raney-Nickel Catalyst

Poisoning Effect of Carbon Disulfide on the Liquid-phase Hydrogenation of Acetone over a Raney-Nickel Catalyst

Kinetics of liquid-phase hydrogenation of acetone over Raney nickel catalyst

Kinetic studies on the liquid-phase hydrogenation of acetone over Raney nickel catalyst were performed over a wide range of concentration in various solvents. The kinetics in n-hexane, cyclohexane, methyl alcohol, and isopropyl alcohol were found to be successfully interpreted on the scheme where hydrogen, acetone, and solvent are adsorbed competitively on the catalyst surface. A rate equation was derived on the basis of the Langmuir-Hinshelwood mechanism. The activation energy was determined to be 10.1 kcal/mole. The relation between the apparent activation energy and the “true” one is also discussed.

Effect of fluorination on acidity of aluminum oxide

The directional solidification (DS) of eutectic Ni-Al alloys was investigated as a new route for the synthesis of catalytic materials of the Raney (trade-mark) type with improved properties. Critical surface properties of the caustic-activated alloys, such as specific surface area, pore structure and available catalytic nickel surface area for active nickel derived from DS precursor alloys, were found to be superior to those of commercial bulk-cast Raney alloys activated in the same manner. Microporosites derived from low temperature nitrogen adsorption isotherms on caustic-activated alloys are significantly greater and pore distributions occur not only in both the small pore sizes with radii of less than about 10 Å and the sizes with radii of about 40–70 Å, which typical of Raney nickles, but also in the coarse pore sizes, with radii of about 90 Å, which are not typical of commercial activated Raney nickels. The enhanced pore structure of these DS caustic-activated alloys was demonstrated to be quite stable toward sintering by air oxidation at temperatures of about 500 °C. The Brunauer-Emmett-Teller surface area and available nickel metal surface area were found also to provide promising stability toward sintering in hot (about 350 °C) reducing atmospheres typical for methanation catalysis.The catalytic performance of caustic-activated DS Ni-Al eutectic alloys, compared with commercial Raney alloys, was found to be consistently superior by factors of 1.14–12.9 for initial reaction rates at low temperature (22 and 80 °C) for six selected liquid phase hydrogenation reactions, i.e. hydrogenation of acetone to isopropanol, nitrobenzene to aniline, toluene to methyl cyclohexane, butyronitrile to butylamine, itaconic acid to methyl succinic acid and dextrose to sorbitol. This superiority was due principally to the greater available catalytic nickel surface but in two instances (butyronitrile and nitrobenzene) the hydrogenation rates on a specific area basis are superior by factors of about 7 and 3 respectively, indicating that selectivity also plays a role.

On the mechanism of acetone hydrogenation

Commercial raw ulexite (U) materials were milled from 0 h to 8 h by using mechanical milling technique for various initial powder size (− 3 mm; − 75 μm), ball to powder ratio (5:1; 10:1), and ball size (10 mm; 5 mm). Particle size, morphology, elemental, and crystal structure measurements of the milled powders were performed. In the particle size distribution analysis, the smallest d50 and d10 values were respectively found as 8.846 μm and 790 nm for U_5m powder (obtained from that initial powder with − 3 mm in size was milled by balls with 5 mm in size) at 0.5 h. In the morphology analysis, the microstructure of the U_5m powder was observed to be more homogeneous by means of milling process. In the elemental analysis, it was deduced that the U_5m powder is not a pure compound. In the crystal structure analysis, it was determined that the crystal structure of the U_5m powder is exponentially deteriorated with increasing the milling time, and then it has become an amorphous structure at the end of 8 h. The crystalline size of the U_5m powder is reduced to 15.5 nm after 4 h of milling. The results of this study are considered to be useful for future nano studies and industrial applications of ceramic ulexite compound, which is a boron mineral.

Catalytic and Structural Characteristics of Nickel Fine Particles

Since a preparation and catalytic activity of "Urushibara-Nickel" were published, some experimental efforts have been devoted by means of X-ray and electron diffraction techniques, but there is little publication indicating a unique relation between any physical or chemical properties of the Ni-fine particles and the catalytic activity, only similar behaviors to "Raney-Nickel" being reoorted.The authors investigated the catalytic activity as a function of crystal (particle) size in the hydrogenation of acetone and various factors influencing the particle size in U-Ni-BA crystals, of which it has been reported that the catalytic activity of U-Ni-BA catalyst changes with the concentration of used Ni-chlorides.As a result of the present experiment, it must be noted that ; (1) the cause of the cata-lytic activity can not be explained only by particle size, (2) in the U-Ni-BA crystals showing a remarkable activity, it was found from X-ray and electron diffraction analyses that "Hexagonal crystals" coexist in normal f.c.c. Ni-fine particles, and it was concluded also that the hexagonal crystals might be h.c.p. Ni included in f.c.c. Ni from the experimental result in which any possibility of existence of Ni-and Al-oxides, hydroxides and other substances was checked by the comparison of their X-ray patterns.

The catalytic hydrogenation of acetone on evaporated metallic films

The catalytic reaction between acetone vapor and hydrogen on evaporated metallic catalysts in a static system has been followed by means of a Nier-type mass spectrometer. The main reaction observed on platinum, nickel, tungsten, iron, palladium, and gold was the formation of isopropanol but small amounts of propane were also formed simultaneously on platinum and, to a lesser extent, on the other metals with the exception of palladium and gold. Activation energies and frequency factors were measured for the production of isopropanol on all the metals and some pressure dependencies were obtained on nickel films. The order of activity of the metals was similar to the order for the hydrogenation of ethylene except for palladium, which was the least active of the five transition metals. A series of values for the equilibrium constant for the dehydrogenation of isopropanol to acetone was obtained at substantially lower temperatures than have been used in previous measurements.

The catalytic hydrogenation of acetone on evaporated metallic films

The catalytic reaction between acetone vapor and hydrogen on evaporated metallic catalysts in a static system has been followed by means of a Nier-type mass spectrometer. The main reaction observed on platinum, nickel, tungsten, iron, palladium, and gold was the formation of isopropanol but small amounts of propane were also formed simultaneously on platinum and, to a lesser extent, on the other metals with the exception of palladium and gold. Activation energies and frequency factors were measured for the production of isopropanol on all the metals and some pressure dependencies were obtained on nickel films. The order of activity of the metals was similar to the order for the hydrogenation of ethylene except for palladium, which was the least active of the five transition metals. A series of values for the equilibrium constant for the dehydrogenation of isopropanol to acetone was obtained at substantially lower temperatures than have been used in previous measurements.

(151)アセトンの水素添加におよぼす水および塩基性物質の影響

(151)アセトンの水素添加におよぼす水および塩基性物質の影響