Shuzo Nakamura

Some Catalytic Applications of ZSM-5 Zeolite: Para-Selective Dealkylation and Vapor Phase Beckmann Rearrangement

Two interesting examples utilizing the weak or low acidity and the shape selectivity of ZSM-5 or Silicalite zeolite are shown. The first one is a para-selective dealkylation of cymenes, and the second one is a vapor phase Beckmann rearrangement of cyclohexanone oxime into e-caprolactam. In the para-selective dealkylation, the para-selectivity was obtained rather easily by impregnation of MgO, but the difficulties were how to obtain a high purity of recovered propylene while keeping a high conversion of p-cymene, and how to prevent a coke deposition. For these purposes, three types of ZSM-5 were found to give good results: MgO/Li·ZSM-5, MgO/(Na+H)·ZSM-5, and very high silicious ZSM-5 or Silicalite with Si/Al ratio more than 5,000, being impregnated also with MgO. In the Beckmann rearrangement, the catalytic activity, the selectivity and also the catalytic life (time-on-stream) were strongly dependent upon the Si/Al ratio of ZSM-5, and H·SM-5 or Silicalite with high Si/Al ratio (≥ 1,000) gave good results.

A new catalyst for the direct synthesis of ethylene glycol from carbon monoxide and hydrogen

Abstract Bulky alkylphosphines (with large cone angles around the P atom), such as P-i-Pr 3 (L), prominently enhance the activity and the stability of the rhodium carbonyl catalyst in the direct synthesis of ethylene glycol from carbon monoxide and hydrogen. Arylphosphines, alkyl- and aryl-phosphites and also alkylphosphines with small cone angles, such as P-n-Bu 3 , all decompose to form the phosphidocarbonyl cluster anion, [Rh 9 P(CO) 21 ] 2− and hence inhibit the catalysis. High pressure IR analysis indicates that HRh(CO) 3 L, rather than anionic rhodium carbonyl clusters, plays an important role in the formation of ethylene glycol. Thus 0.3 mg-atom of Rh 4 (CO) 12 and 0.3 mmol of P-i-Pr 3 in 7.5 ml of 1-methyl-2-pyrrolidinone were allowed to react at 220°C in an autoclave and under 450 kg cm −2 H 2 /CO pressure for 3 h. Turn-over frequencies for ethylene glycol and methanol were 6.2 and 4.3, respectively, and selectivity was 58.8%.

1-Alkylbenzimidazoles as unique promoters for a homogeneous ruthenium catalyst for direct ethylene glycol formation from synthesis gas

Abstract 1-Alkylbenzimidazoles such as 1-methylbenzimidazole and 1,5,6-trimethylbenzimidazole have been found to be excellent promoters for direct ethylene glycol formation from hydrogen and carbon monoxide in the presence of a homogeneous ruthenium catalyst. High pressure IR analyses revealed that three Ru species, [HRu 3 (CO) 11 ] − (I), Ru(CO) 5 (II) and Ru(CO) 4 (1-alkylbenzimidazole) (III) had formed. An analysis of the relationship between activity and identity of Ru species showed that ruthenium species III plays an important role in ethylene glycol formation, and that the high coordination ability of benzimidazoles is essential to the promoting effect on ethylene glycol formation.

Effect of phosphine ligands on homogeneous hydrogenation of carbon monoxide by iridium catalysts

Abstract During the hydrogenation of carbon monoxide by carbonyl iridium catalyst under high pressure, triarylphosphines such as triphenylphosphine were found to enhance the activity and selectivity for ethylene glycol formation, whereas trialkylphosphines mostly promoted methanol formation. The moderate σ-donating ability of the ligand appears to be important for ethylene glycol formation. Crystalline Ir2(CO)6(PPh3)2 was isolated from the reaction mixture. This complex by itself showed a high catalytic activity for ethylene glycol.

Vapor Phase Catalytic Oxidation of Isobutene to Methacrylic Acid

A number of aspects of the two stage vapor phase catalytic oxidation of isobutene to methacrylic acid as related to the design of the industrial catalysts involved are discussed in particular in comparison with the counter parts of the case of propylene to acrylic acid. An overall yield exceeding seventy percent has been attained in the laboratory and that only a few percent less in the pilot.

Ethylene glycol formation from carbon monoxide and hydrogen by homogeneous rhenium catalysts

Rhenium carbonyl, when combined with a halide or acetate salt, was found to exhibit catalytic activity for the direct formation of ethylene glycol from carbon monoxide and hydrogen in N-methylpyrrolidinone solvent under high pressure and temperature. LiCl was found to be the most effective salt. This is the first case in which a non-Group VIII element is reported to catalyze the reaction. IR spectroscopic studies revealed that the halides interact with rhenium in such a manner to increase the electron density of the central metal atom. Nickel was effective as a cocatalyst in promoting the ethylene glycol formation.

Characteristics Of The Mass-Produced Optical Disks

Sumitomos mass production plant for write once optical memory disks has been operational since the summer of 1985. The product disk, which has the sandwich structure with an air gap and which has the sensitive layer based on tellurium, exhibits equal or better read / write characteristics and reliability compared with ones from the laboratory. It will be demonstrated that the disks are particularly suited for high speed and high density data recording at an adequetly low error rate and also that the result of accellerated aging tests assures an excellent archivability.