Kun You Park

Deactivation of Pd catalysts in the hydrodechlorination of chloropentafluoroethane

Abstract The deactivation behavior of Pd catalysts on different supports in the hydrodechlorination of chloropentafluoroethane (CF 3 CF 2 Cl) was investigated. Changes of the BET surface area and the metal percentage exposed, measured by a multipurpose in situ catalyst characterization system during the reaction, gave some information about the deactivation mechanism of the Pd catalysts. The deactivation of the Pd catalysts was mainly caused by sintering of Pd particles rather than by coking. The sintering of Pd particles on the catalyst surface was promoted by the reaction of hydrogen fluoride with the support of the catalysts.

Kinetics of Dimethyl Carbonate Synthesis From Ethylene Carbonate and Methanol Using Alkali-Metal Compounds as Catalysts

Dimethyl carbonate (DMC) was synthesized by the ester exchange reaction of ethylene carbonate and methanol. K2 CO3 , KOH, LiOH and NaOH were used as catalysts for DMC synthesis and their catalytic abilities were compared in terms of kinetics. LiOH showed the best reaction rate among the catalysts. The rate constant was estimated to be 0.02538 (dm 3 /mol) 0.21 /min at 298 K.

Adsorption equilibria of chloropentafluoroethane on activated carbon powder

An equilibrium study was conducted on the adsorption of chloropentafluoroethane (CFC-115, CF3CF2Cl) on activated carbon powder between 298.15 K and 373.15 K. Experimental data were fitted with several isotherm equations. Among the twoparameter equations, the BET equation showed the best results over the entire relative pressure range studied. When the pressure range was divided into two regions, a better result was obtained by applying the Langmuir equation in the lower pressure range and the BET equation in the higher relative pressure region. Among the threeparameter equations, the Langmuir-Freundlich equation gave better results than the RedrichPeterson equation. The isosteric heat of adsorption of CFC-115 on the activated carbon powder was estimated. It was found to have the same order of magnitude with the heat of condensation, which indicates that the adsorption was primarily due to physical forces.

A kinetic study on thermal chlorination of l-chloro-2,2,2-trifluoroethane

HCFC-133a (l-chloro-2,2,2-trifluoroethane) was thermally chlorinated in an integral reactor under atmospheric pressure in a temperature range between 573 and 723 K. From the analysis of the data it was confirmed that the reaction was a two-step series-parallel reaction and each step was a second-order reaction. The ratio of the second-step rate constant to the first-step rate constant did not change with temperature and its value was 1.13. The activation energy was 106 kJ/g-mol. These results indicate that the product distribution is the sole function of conversion of HCFC-133a.