Takanori Miyake

Direct synthesis of phenol by hydroxylation of benzene with oxygen and hydrogen

Direct synthesis of phenol by hydroxylation of benzene with oxygen and hydrogen was investigated on precious metals supported on silica. On Pd, Rh, Ir and Pt, phenol was formed with a large amount of water. Modification of the catalyst was studied with various metal oxides. When the catalyst was modified with vanadium oxide, the phenol formation activity was significantly improved. The best vanadium oxide loading was 1 wt.-%, and laser Raman spectra suggested that vanadium oxide existed as a monomeric species. Oxygen activated on the vanadium species transferred to a Pt site, and as a result the phenol formation activity was promoted. Improved dispersion of precious metals by modification with vanadium oxide seemed to be related to the increase in the rate of phenol formation. Hydroxylation with oxygen and hydrogen was applicable to other aromatic compounds as well.

Benzylacetate synthesis by oxyacetoxylation of toluene on Pd–Bi binary catalyst

Benzylacetate synthesis from toluene, acetic acid and oxygen on Pd–Bi binary catalyst was studied in the liquid phase. By incorporation of Bi with Pd, both the activity and selectivity were improved. Especially better stability was obtained with the catalyst having Pd/Bi = 3. Deactivation of the catalyst was investigated in detail by XRD, XPS, TEM, elemental analysis, EPMA and so on. Comparing the used catalyst with the fresh one, it was indicated that the main cause of deactivation was the dissolution of Pd into the reaction mixture from the most outer surface of the catalyst. By adopting proper reaction conditions to prevent the Pd dissolution, the catalyst having Pd/Bi = 3 was suggested to be used as an industrial catalyst.

Importance of a quasistable V4O9 to synthesize a highly crystalline VOHPO4·0.5H2O

Abstract The organic solvent method to synthesize a highly crystalline VOHPO4·0.5H2O was investigated. Firstly, reduction of V2O5 in alcohols was studied. It was clear that there existed a quasistable V4O9 state after reduction with isobutyl alcohol. When a mixture of isobutyl alcohol and benzyl alcohol was used, the reduction was relatively rapid and difficult to control. Secondly, pure, uniform and roseshaped precursor VOHPO4·0.5H2O was obtained by the dehydration-condensation of V4O9 and ortho-H3PO4 when ortho-H3PO4 was added dropwise. The balance in rates between addition of ortho-H3PO4 and the dehydration-condensation was important to prepare a uniform precursor.

Screening of metal chloride catalysts for oxychlorination of propene

Metal chloride catalysts preferred for oxychlorination of propene were investigated by a simple and useful model oxidation-reduction treatment. Activity and selectivity of the catalyst was correlated with the metal-chloride bonding energy (Em-c1). In the cases of palladium, tellurium and platinum, having an Em-c1 value lower than about 20 kcal/mol, allyl chloride was produced predominantly. In the cases of the catalysts having an EM-C1 value higher than about 30 kcal/mol, no reaction occurred. On the catalyst with medium Em-c1, that is on copper, dichloropropane was mainly formed by the chlorine addition reaction.

Influence of alcohol solvents on characters of VOHPO4·0.5H2O prepared from V4O9 and ortho-H3PO4

Abstract The influence of alcohol solvents on the characters of VOHPO 4 ·0.5H 2 O, precursor of (VO) 2 P 2 O 7 , prepared from V 4 O 9 and ortho -H 3 PO 4 was studied. Valence of vanadium, XRD, SEM, TG/DTA, 31 P-NMR and Raman spectra were used for characterization. Depending on the alcohol solvent used, not only the morphology of particles, but also bulk and surface characters of the precursor VOHPO 4 ·0.5H 2 O were influenced.

Aromatic compounds synthesis from cyclopentadiene

Abstract Aromatic compounds synthesis from cyclopentadiene or dicyclopentadiene was studied with platinum catalysts supported on zeolites under hydrogen atmosphere. It was revealed that aromatic compounds were not formed through cyclopentane and n-pentane, but they were primarily formed by C-C bond scission of bicyclic compounds such as methylindane and tetralin which were derived by the bridge-head C-C bond fracture of dicyclopentadiene. Selectivity to product was supposed to depend both on acidity of the zeolite and on the hydrogenation activity of platinum. The highest BTX yield, about 60%, was obtained on 0.5%Pt/H-ZSM-5.