Thorium oxide catalysts

This is a way to do this procedure without having to use one of those crazy tube furnaces stuffed with thorium oxide or manganous oxide catalyst [21]. The key here is to use an excess of acetic anhydride. Using even more than the amount specified will insure that the reaction proceeds in the right direction and the bad side reaction formation of dibenzylketone will be minimalized (don t ask). 18g piperonylic acid or 13.6g phenylacetic acid, 50mL acetic anhydride and 50mU pyridine are refluxed for 6 hours and the solvent removed by vacuum distillation. The remaining residue is taken up in benzene or ether, washed with 10% NaOH solution (discard the water layer), and vacuum distilled to get 8g P2P (56%). 

Thorium oxide on activated carbon was prepared by absorption of thorium nitrate from its solution in anhydrous acetone on the activated carbon Supersorbon. The excess solution was decanted, the catalyst was dried at 80 °C, and the adsorbed thorium oxide was decomposed by excess 5% ammonium hydroxide solution. After repeated washing and decanta-nation with distilled water and acetone, the catalyst was dried at 180°C. It was then stabilized by heating to 360°C for 5 hr in a stream of nitrogen. The content of thorium oxide was 2.9% (wt.). The BET surface area was 870 m2/g. Prior to kinetic measurements, the catalyst was modified by passing over acetic acid vapors (100 g acid/1 g catalyst). 

Parallel ketonization of acetic acid and propionic acid was one of the transformations of this type studied in our Laboratory. Ryba6ek and Setinek (94) investigated the kinetics of these reactions in the gaseous phase at 316°C using thorium oxide on activated carbon (p. 27) as the catalyst. This model system allowed the study of each reaction separately as well as of the simultaneous conversion of both acids. 

The reaction does not proceed in the absence of catalysts. As the contemporary Fischer-Tropsch catalysts were heterogeneous, the first hydroformylation catalyst was a solid (66% silica, 30% cobalt, 2% thorium oxide, and 2% magnesium oxide). Only later was the conclusion reached and proved (5) that the actual catalytic species is homogeneous. 

Thorium oxide has a high refractive index and low dispersion and thus finds use in high-quality camera and scientific instrument lenses. Thonum oxide also is used as a catalyst in the conversion of ammonia to nitnc acid, in petroleum cracking, and in sulfuric acid production. 

Cyclopentanone has been prepared from adipic acid by distilling the calcium salt,1 heating alone 2 or with acetic anhydride,3 or in the presence of various catalysts such as barium hydroxide,4 thorium oxide,5 manganous oxide,5 uranium nitrate,6 ferrous sulfate 6 and others.7... 

Yellow mercuric oxide reacts only slightly with CO near room temperature, but the activity can be increased markedly by the addition of chromic acid anhydride (58). Thorium oxide is an active catalyst at temperatures above 400°C., and its activity can be increased by the addition of 0.96% Ce203 (60). Vanadium pentoxideis also active at high temperatures (61). 

Rare earth oxides are useful for partial oxidation of natural gas to ethane and ethylene. Samarium oxide doped with alkali metal halides is the most effective catalyst for producing predominantly ethylene. In syngas chemistry, addition of rare earths has proven to be useful to catalyst activity and selectivity. Formerly thorium oxide was used in the Fisher-Tropsch process. Recently ruthenium supported on rare earth oxides was found selective for lower olefin production. Also praseodymium-iron/alumina catalysts produce hydrocarbons in the middle distillate range. Further unusual catalytic properties have been found for lanthanide intermetallics like CeCo2, CeNi2, ThNis- Rare earth compounds (Ce, La) are effective promoters in alcohol synthesis, steam reforming of hydrocarbons, alcohol carbonylation and selective oxidation of olefins. 

The old method of heating the calcium salts of formic and a second carboxylic acid for aldehyde formation has been modified by the use of a catalytic decomposition technique. By this scheme, the acid vapors are passed over thorium oxide, titanium oxide, or magnesium oxide at 300° or the acids are heated under pressure at 260° in the presence of titanium dioxide. In the latter procedure, non-volatile acids can be used. With aliphatic acids over titanium oxide, reaction occurs only when more than seven carbon atoms are present, the yields increasing with increase in the molecular weight (78-90%). Aromatic-acids having halo and phenolic groups are converted in high yields to aldehydes, e.g., salicylaldehyde (92%) and p-chlorobenzaldehyde (8S>%). Preparation of a thorium oxide catalyst has been described (cf. method 186). 

An exception involves the passage of hot alcohol vapors over thorium oxide at 350-450°C, under which conditions Hofmann s mle is followed, and the mechanism is probably different. Cyclobutanol derivatives can be opened in the presence of a palladium catalyst. 2-Phenylbicyclo[3.2.0]octan-2-ol, for example, reacted with a catalytic amount of palladium acetate in the presence of pyridine and oxygen to give phenyl methylenecyclohexane ketone. ... 

The catalyst is prepared as follows An amount of screened pumice (about the size of a pea) sufficient to fill the tube is soaked in hot concentrated nitric acid and then washed thoroughly with hot distilled water. In a porcelain dish the pumice is mixed with a solution of 40 g. of thorium nitrate crystals [Th(N03) 4 + 12H2O] in TOO cc. of water and is evaporated to dryness, with frequent stirring to insure uniform deposition of the salt. The impregnated pumice is ignited over a Bunsen burner until decomposition of the nitrate is complete. The pumice carries about 15 g. of thorium oxide. 

Frank and Caro (D.R.P., 224,329) propose to use thorium oxide as the catalyst. M. Wendriner (Chem. /ud., 1911, p. 456) suggests uranium compounds as catalyst. 

In this process, a mixture of phenylacetic acid and glacial acetic acid is slowly dripped into a Pyrex combustion tube which is filled with pea-sized pumice stones covered with a coating of either thorium oxide or manganous oxide catalyst. This bed of catalyst is heated to a high temperature with a tube furnace and the vapors of phenylacetic acid and acetic acid react on the surface of the catalyst to produce ketones. Three reactions result. 

A somewhat more complicated way to do this reaction is to use what is called a thorium oxide "aerogel" catalyst. A lower temperature and a higher... 

Russian workers have continued their studies on the production of alkyl-pyrrolizidines from furan derivatives by catalytic dehydration. The original catalyst used was thorium oxide on alumina, but improved yields were obtained with zirconium oxide on alumina [Eq. (5)]. In the formation of... 

In addition to uranium, only a few other actinides have commercial uses. Currently, thorium is used to manufacture portable gas lanterns. Thorium oxide is used to make high-quality glass and is also a catalyst in various industrial processes. Plutonium also has commercial uses in uranium reactors and as fuel in nuclear reactors. 

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