Paisan Kongkachuichay

Thermodynamics of adsorption of laccaic acid on silk

Abstract The hybrid-race silk yarn was dyed till equilibrium with natural lac dye (laccaic acid) and the thermodynamics of dyeing were investigated. The adsorption isotherm obtained was identified to be a Langmuir type. When the temperature increased, the partition ratio and the standard affinity decreased drastically. The values of heat of dyeing and entropy of dyeing were−13.20 kcal/mol and-0.03 kcal/mol/K, respectively. The effect of memecylon used as a mordant on silk dyeing with lac dye was also studied. It revealed that using memecylon promoted the adsorption of laccaic acid on silk and increased the attraction between laccaic acid and silk surfaces.

High temperature reactions within SiC–Al 2 O 3 composites

Composites of SiC–Al 2 O 3 and SiC–mullite are unstable at high temperatures. The reactions occurring within the composites between 1700 and 1850 °C in stagnant inert atmospheres were characterized. Gaseous products cause excessive weight losses which cannot be attributed to passive oxidation. These losses can be successfully retarded by processing under high pressures. Compatible phases were determined by x-ray analysis for mixtures lying in the section SiC–Al 4 C 3 −Al 2 O 3 −SiO 2 . The reactions produced condensed phases of Al 2 OC and Al 4 O 4 C as well as gaseous SiO and CO. The condensed phases have high vapor pressures above 1700 °C. The effect of these reactions on densification of composites by firing at different temperatures for various periods under different pressures was studied. Dense materials prepared under high pressures at 1825 °C were tested at 1700 °C under normal pressure in argon, where active oxidation is expected, and weight losses were insignificant.

Compatible phases of the Y 2 O 3 –CuO–Cu 2 O system in air

The phase diagram of the Y 2 O 3 −CuO−Cu 2 O system was constructed as a function of temperature in air by means of thermal analysis and X-ray diffraction. The phase Y 2 Cu 2 O 5 was found to be stoichiometric and melted peritectically at about 1110 o C. A new intermediate phase with the composition YCu 2 O 2.5 was discovered. It exists between 990 and 1105 o C in air and quenching did not preserve it to room temperature. High temperature X-ray diffraction established its pattern and confirmed its peritectic decomposition. Above 1110 o C YCu 2 O 2.5 consits of Y 2 O 3 and liquid

Compatible phases of the Y2O3–CuO–Cu2O system in air

The phase diagram of the Y 2 O 3 −CuO−Cu 2 O system was constructed as a function of temperature in air by means of thermal analysis and X-ray diffraction. The phase Y 2 Cu 2 O 5 was found to be stoichiometric and melted peritectically at about 1110 o C. A new intermediate phase with the composition YCu 2 O 2.5 was discovered. It exists between 990 and 1105 o C in air and quenching did not preserve it to room temperature. High temperature X-ray diffraction established its pattern and confirmed its peritectic decomposition. Above 1110 o C YCu 2 O 2.5 consits of Y 2 O 3 and liquid

Synthesis and Characterization of Silaned-Graphene Oxide-Mordenite Grafting

The grafted materials of silaned-graphene oxide-mordenite (s-GO-MOR) were synthesized by grafting graphene oxide (GO) sheets to acid-treated mordenite and followed by functionalization with silane. GO sheets were prepared according to the modified Hummers method. 3-mercaptopropyltriethoxysilane (MPTES) was used as a silane coupling agent. The products were characterized by a Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. The results confirmed the success of s-GO-MOR and showed excellent thermal stability.

Promotional Effects of Zn Doping on Cu/Core–Shell Al-MCM-41 for Selective Catalytic Reduction of NO with NH3

A Cu-Zn/core-shell Al-MCM-41 catalyst with various Cu and Zn species was investigated for selective catalytic reduction of NO with NH₃. The roles of Zn in the NOx adsorption properties and the acidity of the catalysts were studied by temperature-programmed desorption of NOx and in situ Fourier transform infrared spectroscopy of NO+O₂ adsorption and NH₃ adsorption. The presence of Zn can promote the number of acid sites and improve the NOx adsorption capacity by providing the additional sites for NOx adsorption and subsequent nitrite and nitrate formation. Based on the experimental results, a possible reaction pathway was suggested. Cu-Zn/Al-MCM-41 exhibited higher activity compared with that of Cu/Al-MCM-41, having an average NO conversion of 73%. However, the average NO conversion was increased to 77% when Zn was loaded as ZnO form instead of various Zn species. in situ X-ray adsorption near edge structure during reduction by H₂ revealed that there is a higher number of Cu+ in Cu-ZnO/Al-MCM-41 than that in Cu-Zn/Al-MCM-41. Under wet condition, the average NO conversion of Cu-ZnO/core-shell Al-MCM-41 was dropped to 68%. However, activity of Cu-ZnO/core-shell Al-MCM-41 was more stable than that of Cu-Zn/core-shell Al-MCM-41.

Role of Copper and Cerium on Core–Shell Al-MCM-41 in NO Reduction via a SCR-CH4

Copper species in the structure of Cu/core-shell Al-MCM-41 catalysts prepared by different techniques of Cu loading-substitution (S), ion-exchange (E), and impregnation (I) methods-were tested for NO reduction via a selective catalytic reaction with methane. Cerium was added to enhance the performance of copper. It was found that the 1.5%Ce-SEI-Cu/Al-MCM-41, in which Cu was loaded by all three techniques gave the highest NO conversion of 85% at 500 °C. Based on the results from FT-IR in-situ experiment, the mechanism of SCR-CH4 reaction is proposed. The ion-exchange method gives the best performance of SCR-CH4 reaction when compared with the other methods, because the Cu of reduced catalyst in this method exists in isolated Cu(I), which is an active site of the SCR-CH4 reaction. With H2O in the feed, the NO conversion of 1.5%-Ce-SEI-Cu/Al-MCM-41 catalyst is found to be rather stable.

Compatible phases of the Y sub 2 O sub 3 --CuO--Cu sub 2 O system in air

The phase diagram of the Y 2 O 3 −CuO−Cu 2 O system was constructed as a function of temperature in air by means of thermal analysis and X-ray diffraction. The phase Y 2 Cu 2 O 5 was found to be stoichiometric and melted peritectically at about 1110 o C. A new intermediate phase with the composition YCu 2 O 2.5 was discovered. It exists between 990 and 1105 o C in air and quenching did not preserve it to room temperature. High temperature X-ray diffraction established its pattern and confirmed its peritectic decomposition. Above 1110 o C YCu 2 O 2.5 consits of Y 2 O 3 and liquid