Direct decomposition of NO over the mixed oxide catalysts Nd_(2-)Sr_xNiO_(4±λ)

The nitrogen oxides (NO_x) are serious pollutants in earth's atmosphere in the sensethat they are one of the main sources to cause the acid rain. The removal of NO_x is oneof the key research topics in the protection of environmen.

Comparative study of Nickel-based perovskite-like mixed oxide catalysts for direct decomposition of NO

The mixed oxides LaNiO3, La0.1Sr0.9NiO3, La2NiO4 and LaSrNiO4 were prepared and used as catalysts for the direct decomposition of NO. The catalysts were characterized by means of XRD, XPS, O-2-TPD, NO-TPD and chemical analysis. By comparing the physico-chemical properties and catalytic activity for NO decomposition, a conclusion could be drawn as follows. The direct decomposition of NO over perovskite and related mixed oxide catalysts follows a redox mechanism. The lower valent metal ions Ni2+ and disordered oxygen vacancies seem to be the active sites in the redox process. The oxygen vacancy plays an important role favorable for the adsorption and activation of NO molecules on one hand and on the other hand for increasing the mobility of lattice oxygen which is beneficial to the reproduction of active sites. The presence of oxygen vacancies is one of the indispensable factors to give the mixed oxides a steady activity for NO decomposition.

Studies on the adsorption property of NO on the Ni-based mixed oxide catalysts with Perovskite-like (ABO(3) and A(2)BO(4)) structure

The mixed oxides LaNiO3, La0.1Sr0.9NiO3, La2NiO4 and LaSrNiO4 with perovskite (ABO(3)) and related(A(2)BO(4)) structures were prepared and the adsorption property for NO and the catalytic activity for NO decomposition over these oxidse were also tested. The catalysts were characterized by means of BET surface measurement, chemical analysis, NO-TPD etc.. It was shown that the adsorption amount of NO is correlated with the concentration of oxygen vacancy formed and the adsorption type and strength of NO are related to the valence of metallic ion. Generally there are three kinds of adsorption species, NO-, NO+ and NO on the mixed oxides, among them the negative adsorpion species (NO-) are active for NO decomposition. The weaker the adsorption of oxygen on the catalyst is, the faster the mobility of oxygen is and the easier the redox process takes place in reproducing the active sites in which the oxygen species (O-, O2-) would participate.

Isothermal crystallization studies on neodymium oxide filled nylon 6

Melt mixing of nylon 8 with neodymium oxide particles was carried out with a single-screw extruder. The crystal behaviors of plain nylon 6 and the neodymium oxide filled nylon 6 mixture were studied by means of isothermal crystallization kinetic analysis. Isothermal crystallization thermograms obtained by differential scanning calorimetry (DSC) were analyzed based on the Avrami equation. The neodymium oxide particles acted as a nucleating agent in the mixture. The overall rate of di-isothermal crystallization of the neodymium oxide filled nylon 6 mixture is higher than that of plain nylon 6. The mechanism and modes of plain nylon 6 were the same as those of neodymium oxide filled PA6 mixture.

The direct electrochemistry of cytochrome c at the nanometer-sized rare earth element oxide particle-modified gold electrodes

The direct electrochemistry of cytochrome c was studied at nanometer-sized rare earth element dioxide particle-modified gold electrodes. It was demonstrated that rare earth element oxides can accelerate the electrochemical reaction of cytochrome c and the reversibility of the electrochemical reaction of cytochrome c was related to the size of rare earth element oxide particles.

Poly(epsilon-caprolactone)/poly(ethylene oxide) diblock copolymer .1. Isothermal crystallization and melting behavior

The isothermal crystallization and melting behavior of the poly(epsilon-caprolactone) (PCL)/poly(ethylene oxide)(PEO) diblock copolymer has been studied by WAXD, SAXS, and DSC methods. Only the PCL block is crystallizable; the PEO block of weight fraction 20% cannot crystallize, although its corresponding homopolymer has strong crystallizability. The long period, amorphous layer, and crystalline lamella of the PCL/PEO block copolymer all increase with the rise in the crystallization temperature, and the thickness of the amorphous layer is much larger than that of crystalline lamella due to the existence of the PEO block in the amorphous region. The isothermal crystallization of the PCL/PEO block copolymer is investigated by using the theory of Turnbull and Fischer. It is found that the amorphous PEO block has a great influence on the nucleation of PCL block crystallization, and the extent of this influence depends on crystallization conditions, especially temperature. The outstanding characteristics are the phenomenon of the double melting peaks in the melting process of the PCL/PEO block copolymer after isothermal crystallization at different temperatures and the transformation of melting peaks from double peaks to a single peak with variations in the crystallization condition. They are related mainly to the existence of the PEO block bonding chemically with the PCL block. In summing up results of investigations into the crystallization and melting behavior of the PCL/PEO block copolymer, it is interesting to notice that when the PCL/PEO block copolymer crystallizes at three different crystallization temperatures, i.e., below 0 degrees C, between 0 and 35 degrees C, and above 35 degrees C, the variation of peak melting temperature is similar to that of overall crystallization rates in the process of isothermal crystallization. The results can be elucidated by the effect of the PEO block on the crystallization of the PCL block, especially its nucleation. (C) 1996 John Wiley & Sons, Inc.

The effect of some factors on the electric properties of rare earth complex oxide

The rare earth complex oxides with different types have been synthesized. Their structures and electric properties have been investigated. According to our experimental results, the effects of the outest shell electronic configuration, electron spin state, electron transport path and formation of cluster on the electric properties of rare earth complex oxides have been summarized. When the electrons in the outest shell of the central metallic ion are unpair, and the outest shell is not half-filled, the electric conductibilities of these compounds are better, If there is a -M-X-M-X- or -M-M-M- (the distances between two atoms <0.31 nm) continuous electron transport path, and the electron configurations of the central metallic ion conform to the above condition, then the electric conductibilities are good, The isolate cluster can not become the continuous electron transport path, therefore, the formation of the isolate cluster will reduce the conductibility.

THE COMPATIBILITY AND MORPHOLOGY OF CHITOSAN-POLY(ETHYLENE-OXIDE) BLENDS

Thermal behavior and morphology of blends prepared by solution casting of mixtures of chitosan and poly( ethylene oxide) were studied by means of differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The preliminary results indicate that both melting point and crystallinity depend on the composition of the blends, and that they exhibit minimum values when the blend contains 50% chitosan. From the prediction of melting point depression analysis, the compatibility of the blends shows a transition at this specific composition. This conclusion was further confirmed by observation of the morphology.

STRUCTURE AND PHYSICAL-PROPERTIES OF NEW PHASE OXIDE LA2MOO5

The compound La2MoO5 has a cubic fluorite symmetry. There is strong interaction between the two molybdenum ions (IV). The cubic-La2MoO5 oxide contains separated Mo2O8 clusters and is a semiconductor. The electrical resistivity measurement shows a semiconductor-metal transition around 250 degrees C. Temperature dependence of magnetic susceptibility represents the Curie-Weiss law. The compound La2MoO5 exhibits a paramagnetic behaviour from 170-250 K.

SYNTHESIS OF A POLYETHYLENE-GRAFT-POLYSTYRENE COPOLYMER AND ITS COMPATIBILIZATION FOR LINEAR LOW-DENSITY POLYETHYLENE/POLY(PHENYLENE OXIDE) BLENDS

Based on unsteady diffusion kinetics, polyethylene(PE)-graft-polystyrene (PS) copolymers were designed and synthesized with a heterogeneous high yield titanium-based catalyst by copolymerization of ethylene with a PS-macromonomer using 1-hexene as a short chain agent to promote the incorporation of the PS-macromonomer. The presence of 1-hexene facilitated the diffusion of the PS-macromonomer, giving rise to the significantly increased incorporation of the PS-macromonomer. Compatibilization of blends of linear low density polyethylene (LLDPE)/poly(phenylene oxide) (PPO) with the PE-g-PS copolymer were investigated using scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA).

MISCIBILITY STUDIES OF POLY(ETHYLENE OXIDE)-POLY(VINYL ACETATE) BLENDS BY VISCOMETRY METHODS

The intrinsic viscosities of poly(ethylene oxide)-poly(vinyl acetate) blends (PEO-PVA) have been measured in chloroform as a function of molecular weights of blend components and compositions. The interaction parameters Delta b obtained from the modified Krigbaum and Wall theory and the differences between the intrinsic viscosities of polymer mixtures and the weight-average intrinsic viscosities of the two blend components were both used to characterize the extent of miscibility of the blend mixtures. (C) 1995 John Wiley and Sons, Inc.

ELECTROCATALYTIC PROPERTIES OF MIXED-VALENCE MOLYBDENUM OXIDE THIN-FILM MODIFIED MICROELECTRODES

A compact blue conducting mixed-valence Mo (VI,V) oxide film was grown on the surface of a carbon fibre (CF) microelectrode by cycling the potential between +0.20 and similar to 0.70 V SCE in freshly prepared Na2MoO4 solution in H2SO4 (pH 2). The thicknes

COMPATIBILIZATION OF POLYPROPYLENE POLY(ETHYLENE OXIDE) BLENDS AND CRYSTALLIZATION BEHAVIOR OF THE BLENDS

The compatibilization of incompatible polypropylene (PP)/poly(ethylene oxide) (PEO) blends was studied. The experimental results showed that the graft copolymer [(PP-MA)-g-PEO] of maleated PP (PP-MA) and mono-hydroxyl PEO (PEO-OH) was a good compatibilize

STRUCTURE AND CATALYTIC ACTIVITY FOR PROPYLENE OXIDATION OF BI-MO-NB COMPLEX OXIDE CATALYSTS

The structure and catalytic,activity for propylene oxidation of series oxides B2Mo3-3X-Nb2XO12-4X (X=0.00, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25) have been studied by means of XRD, IR, Raman, SEM, ESR and so on. The results showed that in the range of X < 0.

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF GASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .3. SORPTION BEHAVIOR OF WATER-VAPOR IN PPO AND SULFONATED PPO MEMBRANES

Water vapor absorption and desorption by poly (phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30-degrees-C and over a broad range of water activity (0.05 less-than-or-equal-to a < 0.8) by the weighing