Hwaung Lee

CO2 Recovery from Flue Gas by PSA Process using Activated Carbon

An experimental study was performed for the recovery of CO2 from flue gas of the electric power plant by pressure swing adsorption process. Activated carbon was used as an adsorbent. The equilibrium adsorption isotherms of pure component and breakthrough curves of their mixture (CO2 : N2 : O2=17 : 79 : 4 vol%) were measured. Pressure equalization step and product purge step were added to basic 4-step PSA for the recovery of strong adsorbates. Through investigation of the effects of each step and total feed rate, highly concentrated CO2 could be obtained by increasing the adsorption time, product purge time, and evacuation time simultaneously with full pressure-equalization. Based on the basic results, the 3-bed, 8-step PSA cycle with the pressure equalization and product purge step was organized. Maximum product purity of CO2 was 99.8% and recovery was 34%.

Conversion of methane to higher hydrocarbons in pulsed DC barrier discharge at atmospheric pressure

Conversion of methane to C2/C3 or higher hydrocarbons in a pulsed DC barrier discharge at atmospheric pressure was studied. Non-equilibrium plasma was generated in the barrier discharge reactor. In this plasma, electrons which had sufficient energy collided with the molecules of methane, which were then activated and coupled to C2/C3 or higher hydrocarbons. The effect of the change of applied voltage, pulse frequency and methane flow rate on methane conversion, selectivities and yields of products was studied. Methane conversion to higher hydrocarbons was about 25% as the maximum. Ethane, propane and ethylene were produced as primary products, including a small amount of unidentified C4 hydrocarbons. The selectivity and yield of ethane as a main product came to about 80% and 17% as the highest, respectively. The selectivities of ethane and ethylene were influenced not by the change of pulse frequency but by the change of applied voltage and methane flow rate. However, in case of propane, the selectivity was independent of those condition changes. The effect of the packing materials such as glass and A12O3 bead on methane conversion was also considered, showing that A12O3 played a role in enhancing the selectivity of ethane remarkably as a catalyst.

Reaction pathways of methane conversion in dielectric-barrier discharge

Conversion of methane to C2, C3, C4 or higher hydrocarbons in a dielectric-barrier discharge was studied at atmospheric pressure. Non-equilibrium plasma was generated in the dielectric-barrier reactor. The effects of applied voltage on methane conversion, as well as selectivities and yields of products were studied. Methane conversion was increased with increasing the applied voltage. Ethane and propane were the main products in a dielectric-barrier discharge at atmospheric pressure. The reaction pathway of the methane conversion in the dielectric-barrier discharge was proposed. The proposed reaction pathways are important because they will give more insight into the application of methane coupling in a DBD at atmospheric pressure.

Methanol Synthesis Over Cu and Cu-Oxide-Containing

Initially developed for more than 20 years ago, the copper over zinc and aluminum oxide (ZnO/Al2O3) catalyst system is used for low-pressure methanol synthesis. Recently, the Cu/ZnO/Al2O3 (CZA) was shown to be active in a dielectric-barrier discharge (low-temperature plasma). In this paper, the investigation on the copper as the active site of the catalyst was discussed on the basis of experimental results and its characterization analysis. The catalyst was attempted to aid the reaction performance of partial oxidation of methane in order to produce methanol. All CZA-based catalysts were successful in increasing methanol selectivity, and the Cu oxide performed better than a metallic-copper catalyst.

\hbox{ZnO}/\hbox{Al}_{2}\hbox{O}_{3}

Spherical nanostructured γ-Al2O3 granules were prepared by combining the modified Yoldas process and oil-drop method, followed by the Pt impregnation inside mesopores of the granules by incipient wetness method. Prepared Pt/γ-Al2O3 catalysts were reduced by novel method using plasma, which was named plasma assisted reduction (PAR), and then used for methane conversion in dielectric-barrier discharge (DBD). The effect of Pt loading, calcination temperature on methane conversion, and selectivities and yields of products were investigated. Prepared Pt/γ-Al2O3 catalysts were successfully reduced by PAR. The main products of methane conversion were the light alkanes such as C2H6, C3H8 and C4H10 when the catalytic plasma reaction was carried out with Pt/γ-Al2O3 catalyst. Methane conversion was in the range of 38–40% depending on Pt loading and calcination temperature. The highest yield of C2H6 was 12.7% with 1 wt% Pt/γ-Al2O3 catalysts after calcinations at 500 ‡C.

Using Dielectric Barrier Discharge

This paper presents a direct comparison of the vibrational spectra between quantum mechanistic calculation and ultrashort laser pulses (USLP) spectrometer for chloroform oxidation. The chloroform decomposition was conducted in the presence of oxygen by using a gliding-arc plasma. In agreement with the prediction from both ab initio density functional theory calculation and USLP spectra analysis, it shows that the early step of the chloroform decomposition by oxygen follows a mechanism of CHCl3 + O2 rarr CCl3OOH rarr COCl2 + OH + Cl.