Active components and mechanism of isobutane alkylation with butenes in the catalytic system of HPAs plus AcOH

The catalytic active phase (CAP) of a novel liquid catalyst for isobutane alkylation with butenes was investigated, the composition of the CAP was analysized, The components of the catalytic active phase were separated and examined by the methods of FTIR, UV and NMR etc., On the basis of these results, a reaction mechanism based on the formation of protonated heteropolyacid as an intial stage in the isobutane alkylation with butenes was postulated, which is in agreement with the experimental results.

A study on the catalytic behaviors of concentrated heteropolyacid solution - I. A novel catalyst for isobutane alkylation with butene

The catalytic behaviors of a novel liquid acid catalyst (composed of heteropolyacid and acetic acid) for alkylation of isobutane with butene was investigated. As a solvent acetic acid had a synergistic effect. It enhanced the acid strength of HPA and its stability. The conditions for the formation of the catalytically active phase were studied systematically. The content of crystal water of HPA and the quantity of solvent affect the formation of active phase and the catalytic activity. Catalytically active phase consists of HPA, acetic acid and hydrocarbon produced from the reaction, as well as traces of water from the crystal water of HPA. This catalyst system is comparable to the sulfuric acid in catalytic activity.

Studies on the alkylation of isobutane with butene over WO3/ZrO2 strong solid acid (I) - Effect of preparation, load of WO3 and calcination temperature

A series of WO3/ZrO2 strong solid acid prepared under different conditions were studied. Their crystal structures, surface properties and acidities were determined by means of XRD, DTA-TG, H-2- TPR, Laser Raman and acidity measurements. The results revealed that ZrO2 in WO3/ZrO2 existed mainly in tetragonal phase, the addition of WO3 plays an important role to stabilize tetragonal phase of ZrO2 and thus the catalyst had a considerable surface area. WO3 in WO3/ZrO2 was dispersed and crystalized in WO3 crystalite on ZrO2 surface and partly reacted with ZrO2 to form the bond of Zr-O-W, which acts as the strong solid acid site. The catalytic properties of WO3/ZrO2 strong solid acid for alkylation of iso-butane with butene under the different conditions were investigated. They had a better reaction performance than other strong solid acids, a parallel relationship could be drawn between the catalytic activity and the amount of acid sites as well as the acidic strength of the catalysts.

Study of the catalytic behaviors of concentrated heteropolyacid solution. I. A novel catalyst for isobutane alkylation with butenes

A novel liquid acid catalyst, composed of heteropolyacid and acetic acid for the alkylation of isobutane with butenes is reported. The conditions for the formation of catalytic active phase as well as its catalytic behaviors in alkylation of isobutane with butenes have been studied. It was found that acetic acid, as a solvent, exerts a synergistic effect on the acid strength of heteropolyacid, and the contents of crystal water in HPAs have influence over the formation of active phase and the catalytic activity. This novel catalyst is comparable to the sulfuric acid in catalytic activity.

Isobutane/butene alkylation over supported heteropoly acid catalysts: I. Influence of the structure of silica

Catalysts consisting of heteropoly acids (HPAs) supported on different silica and mesoporous molecular sieves have been prepared by impregnation and the sol-gel method, respectively, and their catalytic behavior in fixed-bed alkylation of isobutane with butene has been investigated. The activity, selectivity and stability of the supported-HPA catalysts could be correlated with the surface acidity of the catalysts, the structure of supports as well as the time on stream (TOS). In the fixed-bed reactor, the acidity of the heteropoly acid is favorable to the formation of dimerization products (C-8(=)); especially, the pore size of supports was seen to have an important effect on activity and product distribution of the catalysts. Contrary to the traditional solid-acid catalysts, the supported-HPA catalysts own an excellent stability for alkylation, which makes it possible for these supported catalysts to replace the liquid-acid catalysts used in industry.

ALKYLATION OF ISOBUTANE WITH BUTENE OVER LAYERED DOUBLE HYDROXIDE PILLARED HETEROPOLYOXOMETALATE ACID-BASE CATALYSTS

[Si(W2O7)(6)](8-) pillared LDH structure hydroxides were synthesized by the method of restructuring of the thermally decomposed hydrotalcite-like compounds for Zn-Al and Mg-Al oxide systems. [P(W2O7)(6)](8-) pillared Ni-Al LDH structure hydroxide was synt

ASYMMETRIC ALKYLATION MEDIATED BY CHIRAL PHASE-TRANSFER CATALYSTS

Seven chiral phase-transfer catalysts, among which three have not been reported so far, have been prepared and applied to the asymmetric alkylation of alpha-isopropyl benzyl cyanide and alpha-isopropyl-p-chlorobenzyl cyanide. The result showed that short reaction time, low temperature, high catalyst concentration and non-polar solvent would improve the optical yield. The influence of structure of the catalyst on the asymmetric reaction was preliminarily studied. The optical purity of the products were evaluated by gas chromatography with a chiral column.

Effect of ethanol extract of alga Laurencia supplementation on DNA oxidation and alkylation damage in mice

Laurencia terpenoid extract (LET) had been extracted from the red alga Laurencia tristicha. The study is to investigate the effects of LET supplementation on DNA oxidation and alkylation damages in mice. Forty healthy kunming mice weighing between 18g and 25g were randomly assigned into 4 groups, each consisting of ten animals. The mice were orally intubated respectively for 60 days with the designed concentrations of LET (25, 50, 100 mg/kg b.w.) for three exposed groups and salad oil (0.2 ml) for the blank group. Food and water were free for the animals. Mice in the blank and exposed groups were sacrificed after the last treatment and the blood of each animal was quickly taken for further experiments. The spontaneous and oxidized DNA damages of peripheral lymphocytes induced by H2O2 were analysed by SCGE. O-6-Methy-guanine (O-6-MeG) was measured by high performance capillary zone electrophoresis. There was no significantly difference in DNA spontaneous damage on peripheral lymphocytes of all the mice. The oxidative DNA damage in the 50 mg/Kg body weight supplement group are 286AU with the oxidation of 10 mu mol/L H2O2, significantly lower than the blank group 332AU (p<0.05). The contents of O-6-MeG in plasma in the 50mg/kg b.w. and 100mg/kg b.w. supplement group were 1.50 mu mol/L andl.88 mu mol/L, significantly lower than that of the blank group, which was 2.89 mu mol/L(p<0.05). The results from the present study indicated that the LET were rich in terpenoids and safety to be taken orally and it could improve antioxidative and decrease DNA damage effectively.

Ferrocenylphosphine-imine ligands for Pd-catalyzed asymmetric allylic alkylation

Ferrocenylphosphine-imine ligands 6 derived front (R,S)-PPFNH2-R 5 and a variety of benzaldehydes were applied in the Pd-catalyzed asymmetric allylic alkylation of 1,3-diphenylprop-2-en-1-yl acetate 7a or pivalate 7b with dimethyl malonate. The substituent effects on the catalytic reaction were investigated, and 96% e.e. with 99% yield was achieved when the m-nitro substituted ligand 6k was used. (C) 2002 Elsevier Science Ltd. All rights reserved.