Presence Of γ-Al2O3 Research Articles

Kinetic studies of methylmercaptan production from dimethyl sulfide and H2S

Kinetic regularities of methylmercaptan production from dimethyl sulfide and H2S in the presence of γ-Al2O3 have been studied under gradientless conditions. A stepwise reaction mechanism is suggested implying that the catalyst surface is methoxylated by methyl sulfide and then CH3O groups interact with H2S. The kinetic equation obtained describes fairly well this process on the nonhomogeneous catalyst surface.

Conversion of alkylmercaptans in the presence of γ-Al2O3

In the presence of γ-Al2O3 at 200–500°C methylmercaptans quantitatively transform into dimethyl sulfides with almost equilibrium degrees of conversion. 100% selectivity towards diethyl sulfide is observed when ethylmercaptan conversion amounts to about 50% of its equilibrium value. In more severe conditions, dimethyl- and diethyl sulfides convert with eliminating hydrocarbons and H2S. Selectivity towards diisopropylsulfide is as high as 30% with isopropylmercaptane conversion up to 25%; the reaction follows a parallel-consecutive scheme.

Phase transition of the dispersed system LiIO3 (γ-Al2O3)

The increase of phase transition temperatures both from α-to γ-phase and from γ-to β-phase of LiIO3 in the dispered system LiIO3 (γ-Al2O3) has been observed. The ζ-phase can be stabilized to ambient condition by the presence of γ-Al2O3. The stability of γ-LiIO3 and ζ-LiIO3 is improved by the addition of γ-Al2O3.

Cyclotrimerization of ethylene and ethane in presence of Rh, Ru, and Ir catalysts, and Al2O3

1. In the presence of Rh-, Ru-, and Ir-Al2O3 the cyclotrimerization of ethylene proceeds under milder conditions than on Pt/Al2O3. 2. The Ru, Rh, and Ir catalysts are active in the dehydrocyclotrimerization of ethane to aromatic hydrocarbons. 3. The cyclotrimerization of ethylene can also proceed in the presence ofγ-Al2O3.

Cyclization of crotyl phenyl sulfide in the presence of acid catalysts

Crotyl phenyl sulfide is converted to 2-ethyl-2,3-dihydrobenzothiophene and 2- and 4-methylthiochromans in the presence of γ-Al2O3 and 5, 10, and 20% ZnCl2/Al2O3 at 300°C and is also isomerized to 1-butenyl- and 3-butenyl phenyl sulfides and cleaved to thiophenol.

Heterogeneous-catalytic fischer reaction

The catalytic synthesis of 7-azaindole and its 2-methyl derivative has been accomplished for the first time by cyclization of acetaldehyde and acetone 2-pyridylhydrazones in the presence of γ-Al2O3 and fluorinated aluminum oxide. The temperature dependence of the yields of reaction products — azaindoles and 2-aminopyridine — was studied. The cyclization of acetaldehyde 2-pyridylhydrazone proceeds under more severe conditions. The maximum yield of 7-azaindole is 15% at 450° on fluorinated aluminum oxide. The yield of 2-methyl-7-azaindole reaches 50% at 315°. Fluorinated aluminum oxide displays higher catalytic activity.