Preparation condition effect

Alcohol and aldehyde decarbonylation on Rh(l 11), activation of C-H, C-C, and C-0 bonds, 345-353 Alkane dehydroeyelization with Pt-Sn-alumina catalysts aromatic formation, 120 preparation condition effect, 119... 

Preparation conditions of Pd/CNFs by wet impregnation method, such as palladium precursor, impregnation time, calcinations and reduction, are proved to have profound effect on the catalytic property. The catalyst prqjared by impregnating HzPdCLi precursor in an hour, then calcinated in air and reduced in 20%H2/Ar is believed to perform better in CTA hydropurification than the industrial Pd/C under laboratory conditions. 

Today of course this understanding has evolved and we have a broader picture of the factors governing the chemical behaviour of these materials, whose mild preparation conditions were soon shown to be compatible with the effective entrapment of biomolecules (with no loss, and often with enhancement, of biological activity) opening the route to the merger of chemistry, biology and materials science (Figure 1.2).8... 

Recently, we reported that an Fe supported zeolite (FeHY-1) shows high activity for acidic reactions such as toluene disproportionation and resid hydrocracking in the presence of H2S [1,2]. Investigations using electron spin resonance (ESR), Fourier transform infrared spectroscopy (FT-IR), MiJssbauer and transmission electron microscopy (TEM) revealed that superfine ferric oxide cluster interacts with the zeolite framework in the super-cage of Y-type zeolites [3,4]. Furthermore, we reported change in physicochemical properties and catalytic activities for toluene disproportionation during the sample preparation period[5]. It was revealed that the activation of the catalyst was closely related with interaction between the iron cluster and the zeolite framework. In this work, we will report the effect of preparation conditions on the physicochemical properties and activity for toluene disproportionation in the presence of 82. ... 

These results and the comparison between the catalyst particles before and after catalytic run point out the ability for these particles both to exchange electrons and oxygen anions and to change morphology under the conditions of the catalytic reaction with spreading of the oxides one over the other. These two phenomena should be at the basis of the explanation of synergy effect in molybdates based catalysts. The fact that some FexCoi.xMo04 particles remain free (i.e. not deposited on bismuth molybdate particles) show that even more active and selective catalysts may be obtained in more reliable preparation conditions. 

The effect of fast neutron fluence on thermal conductivity and thermopower has been determined by Uher and Huang (70). For fluences to 3 x 1018 n/cm2 Tc decreases in Y-Ba-Cu-O to a temperature of 86 K, the thermal conductivity decreases and is without a peak above Tc and the thermopower starts from a negative value and approaches zero and becomes positive. As will be seen below the more usual value of thermopower is positive in the superconducting material but these authors note the variability dependent on sample preparation conditions. 

In order to develop physically stable preparations, the effect of tablet composition as well as the effect of storage conditions on the behaviour of physical tablet properties during storage must be studied. 

Fanta, G. F., Felker, F. C., Shogren, R. L., Saleh, J. H. (2008). Preparation of spherulites from jet cooked mixtures of high amylose starch and fatty acids. Effect of preparative conditions on spherulite morphology and yield. Carbohydrate polymers, 71, 253-262. 

Poly(ether sulfone) and poly(ether ketone) rotaxanes 77, 78, 79, and 80 were reported by Xie and Gong via solution polymerization in a mixture of toluene and DMF in the presence of metal ions (K+ or Na+) and 30C10 [114, 123]. The min values depended on the reaction conditions and the amount of BG applied [114, 123]. Polyrotaxanes 77 and 78 were difficult to purify because these polymers formed emulsions in water or methanol. Because of different preparation conditions between those with or without BG, the absolute m/n values are not comparable and thus the effect of the BG on threading remains unknown. However, considering that a polar solvent, i.e., DMF, was used for polymerization, these m/n values are still significant. 

Fig. 8. Linear swelling ratio calculated for ionized NIPA gels. Numbers on curves represent the effective number of charges per polymer chain. Structural parameters were calculated from the preparation condition of the samples. Other parameters were identical with those used in the calculations for neutral NIPA gels...

A Raney Ni catalyst modified by tartaric acid and NaBr is fairly effective for enantioselective hydrogenation of a series of (3-keto esters (Scheme 1.41) [203a,214,215]. The enantio-discrimi-nation ability of the catalyst is highly dependent on the preparation conditions such as pH (3—4), temperature (100°C), and concentration of the modifier (1%). Addition of NaBr as a second modifier is also crucial. Ultrasonic irradiation of the catalyst leads to even better activity and enantioselectivity up to 98% ee [214d-f. The Ni catalyst is considered to consist of a stable, selective and weak, nonselective surface area, while the latter is selectively removed by ultrasonication. 

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