Showing papers by "Tse-Chuan Chou published in 1990"

Recovery of silica from the gasification of rice husks/coal in the presence of a pilot flame in a modified fluidized bed

Abstract: Combustion of rice husks with and without coal in the presence of a pilot flame in a modified fluidized bed was investigated in the present study. The process was employed to produce raw silica from rice husks by burning off other organic matters. The chemical and physical properties of both the top and the bottom products from the rice husk combustion were found to be strongly influenced by two major factors: the feed rate and the feed composition. It has also been found that coal fed along with rice husks to the combustion process permits easy control of the properties of both solid products and significantly reduces the agglomerating phenomena that occur often in the process. The temperature distribution of the fluidized bed, which reflects the bed operating characteristics, was measured and observed to depend on the frequency of pulsed solid feed.

Kinetics of the oxidation of benzyl alcohol by hypochlorite ion in the presence of phase-transfer catalyst

Abstract: The kinetics of the oxidation of benzyl alcohol by hypochlorite ion in the presence of tetrabutylammonium chloride as phase-transfer catalyst was studied. The results show that the oxidation of benzyl alcohol in two immiscible aqueous/dichloromethane systems was reaction controlled and occurred in the organic phase when the stirring rate was larger than 500 rpm. The experimental results also reveal that the reaction orders of both tetrabutylammonium ion pair and benzyl alcohol in the organic phase are both equal to one. The activation energy of the oxidation of benzyl alcohol is 10.4 kcal/mol. The extraction constant of tetrabutylammonium hypochlorite ion pair was obtained. The equilibrium constants, K 1 −K 4 , are evaluated to be equal to 0.05 M −1 , 17.4, 0.004 M −1 , and 87.7, respectively

Kinetics of the anodic oxidation of benzyl alcohol in dichloromethane in the presence of redox mediator and phase transfer catalyst

Abstract: The kinetics of the anodic oxidation of benzyl alcohol in the two-phase system involving both, the redox mediator, OCl−/Cl−, and a phase transfer catalyst were investigated. The reaction order of the anodic oxidation of chloride ion in the aqueous phase was unity. The charge-transfer parameters, α,k 2 0 and the exchange current density,i0, of the anodic oxidation of chloride ion in the aqueous phase were obtained. The theoretical model calculations correlated well with experimental data. The fractions of anodic surface covered by the aqueous phase were evaluated to be 0.89, 0.61, and 0.23 when the organic-to-aqueous volume ratios were 0.5, 1.0, and 2.0, respectively.

Heterogenized homogeneous catalyst. 4. Catalyst with a bias active site distribution

Abstract: A heterogenized homogeneous catalyst with a bias active site distribution was investigated. The polymer supports of the catalyst with a bias active site distribution were designed and prepared by means of controlling the sulfonation reaction of the polystyrene resin. The results showed that the reaction rate of aldehyde oxidation increased with an increase of the film thickness with a bias active site of the catalyst particle and reached a maxima when the film thickness with a bias active site was equal to the catalytically effective thickness. The turnover number, however, decreased sharply with an increase of the film thickness with a bias active site of the particle. The results also showed that the reaction rate and the turnover number of aldehyde oxidation initiated by the heterogenized homogeneous catalyst with a bias active site distribution was larger and 100 times higher, respectively, than that of using a Co-type catalyst supported by the commercial resin. The behavior of the heterogenized homogeneous catalyst was much more improved when using the catalyst with a bias active site distribution.

Epoxidation of oleic acid with oxygen in the presence of benzaldehyde using heterogenized homogeneous co‐type ion‐exchange membrane as catalyst

Abstract: The epoxidation of oleic acid with oxygen in the presence of benzaldehyde to produce epoxidized oleic acid using a Co-type ion-exchange membrane as catalyst was carried out. No leakage of cobalt ion was found during the experimental runs. The epoxidized oleic acid was formed by a series of free radical reactions. Experimental results show that at 70% conversion of oleic acid, 60% of the total theoretical epoxidized oleic acid was obtained, illustrating the high selectivity (86%). The rate-determining steps were experimentally identified and the formation rate of epoxidized oleic acid was found. On a procede a l'epoxydation de l'acide oleique avec de l'oxygene en presence de benzaldehyde pour produire de l'acide oleique epoxyde en utilisant une membrane echangeuse d'ions de type Co comme catalyseur. Aucune fuite d'ion cobalt n'a ete trouvee durant les essais experimentaux. L'acide oleique epoxide a ete forme par une serie de reactions a radicaux libres. Les resultats experimentaux montrent qu'a une conversion de 70% de l'acide oleique, on obtient 60% de l'acide oleique epoxyde theorique total, ce qui illustre la haute selectivite (86%). On a identifie experimentalement les etapes determinant la vitesse et on a trouve la vitesse de formation de l'acide oleique epoxyde.