Aurel Ujhidy

Membrane permeation of water—alcohol binary mixtures ☆

Abstract The permeability and selectivity of nylon-6, cellophane, and cellulose 2.5-acetate membranes toward binary mixtures of aliphatic alcohols and water were studied at 60°C. Commercial membranes made of the above materials were used with and without preswelling. The cellophane membranes swelled considerably more than the other types of membranes in both water and in aqueous isopropanol mixtures containing over 40 mole% H 2 O. Therefore, the effects of swelling on membrane permeability were examined in some detail with cellophane membranes. The permeability characteristics of cellophane membranes could be altered significantly by suitable pretreatment. The effects of pretreatment are negligible in the case of cellulose 2.5-acetate and nylon-6 membranes.

Enhancement of gas absorption rate as a function of the particle size in slurry reactors

Abstract Exact relationships are given for the enhancement of gas absorption rate as a function of particle size in a three-phase slurry reactor. The solid-liquid mass transfer in the liquid film at the gas-liquid interface is considered as a transfer through spherical surface. The solid phase is the catalyst or reactant. The enhancement of the gas absorption rate calculated by the given equations are in very good agreement with the experimental data as a function of particle size and solid phase concentration.

Hydroisomerization of n-hexane on mordenite shell-catalyst

Abstract Synthetic and natural mordenites were used for the preparation of bulk and shell-catalysts in order to compare their catalytic characteristics. Hydroisomerization of n-hexane was applied as a test reaction. The catalytic activity of shell-catalysts was markedtly higher than that of bulk-catalysts although the amount of the active substance was the same. The decrease of shell thickness raised the catalytic activity and decreased the amount of coke deposited on the catalyst surface. The variation of the catalytic properties could partly be explained by the change of number and strength of the acidic centres.