Catalytic activity measurements

The measures of solid state reactivity to be described include experiments on solid-gas, solid-liquid, and solid-solid chemical reaction, solid-solid structural transitions, and hot pressing-sintering in the solid state. These conditions are achieved in catalytic activity measurements of rutile and zinc oxide, in studies of the dissolution of silicon nitride and rutile, the reaction of lead oxide and zirconia to form lead zirconate, the monoclinic to tetragonal transformation in zirconia, the theta-to-alpha transformation in alumina, and the hot pressing of aluminum nitride and aluminum oxide. 

D. Tsiplakides, J. Nicole, C.G. Vayenas, and C. Comninellis, Work function and catalytic activity measurements of an Ir02 film deposited on YSZ subjected to in situ electrochemical promotion,/. Electrochem. Soc. 145(3), 905-908 (1998). 

Fig. 8 Dependence of catalytic activity measured by TOP (rate of reaction per Rh atom) (squares) and IR intensity of hydride (2020-cm mode) (diamonds) during the induction period for ethene hydrogenation catalyzed by Rhg supported on La203 at 298 K and atmospheric pressure in a flow reactor (partial pressures in feed H2, 348 Torr C2H4, 75Torr He, 337 Torr) [37]...

The allosteric model for AMP inhibition of FDPase is supported by the results of experiments in which the enzyme is desensitized to the inhibitor with little or no loss of catalytic activity. Mild digestion with papain causes almost complete loss of AMP inhibition under conditions where the catalytic activity is only slightly decreased (13). Indeed the catalytic activity measured at alkaline pH has been observed to increase (36). 

Catalytic activity measurements. Alkali metal ion X and Y zeolites show no activity for hydrocarbon conversions involving carbonium ion intermediates. Ward (210) showed that the decomposition of cumene to benzene and propylene did not occur over Na—Y zeolite at 260°C, whereas extensive conversion took place with H—Y and alkaline earth ion-exchanged forms. Similarly, isomerization of o-xylene at 250°C did... 

Catalytic activity measurements and correlations with surface acidity have been obtained by numerous investigators. The reactions studied most frequently are cracking of cumene or normal paraffins and isomerization reactions both types of reactions proceed by carbonium ion mechanisms. Venuto et al. (219) investigated alkylation reactions over rare earth ion-exchanged X zeolite catalysts (REX). On the basis of product distributions, patterns of substrate reactivity, and deuterium tracer experiments, they concluded that zeolite-catalyzed alkylation proceeded via carbonium ion mechanisms. The reactions that occurred over REX catalysts such as alkylation of benzene/phenol with ethylene, isomerization of o-xylene, and isomerization of paraffins, resulted in product distribu-... 

As the quantity of fouling agents necessary to bring about a noticeable change in activity/sclcctivity is relatively large, characterization by methods other than catalytic activity measurements is useful. The rate of... 

If catalytic activity measurements are to be performed simultaneously with the Raman spectroscopy, the cells have to also meet the specifications of catalytic reactors, such as the following ... 

Catalytic Activity Measurement. The reaction was carried out in a stainless steel microflow reactor. In each run, 2 g catalyst was placed in the reactor and heated to 520 °C under a nitrogen stream. The nitrogen stream was replaced by a light naphtha vapor fed by a micro plunger pump. The reaction was carried out at 520 °C, under various pressures and WHS Vs without any hydrogen addition. The products were analyzed periodically by gas chromatography. The properties of the light naphtha are shown in Table I. 

Molecular strucmre and reactivity of vanadia-based catalysts for propane oxidative dehydrogenation smdied by in sim Raman spectroscopy and catalytic activity measurments. Journal of Catalysis, 111 (2), 293-306. 

Catalytic Activity. The cracking of isooctane was studied. For catalytic activity measurements, the samples were heated in flowing helium or hydrogen from room temperature to 465°C for 15 hours. Then the gas saturated with isooctane passed through the catalyst in the microreactor and was analyzed by gas chromatography. 

The results of catalytic activity measurements with the different space velocity are summarized in Table 2. 

Catalytic activity measurements In CH steam reforming were carried out at... 

Another, more probable, explanation is based on a mechanism assuming that the reaction takes place at the periphery of the Au particles. Since the sample used for catalytic activity measurements was composed of Au islands with a certain size distribution, whereas the band gap was measured for a specific Au island by STS, a more reasonable interpretation is that the ratio of the number of surface atoms of Au... 

Catalytic activity measurements were carried out in a fixed bed quartz reactor of inner diameter 6 mm. The catalyst (usually 200 mg, 125-212 pm fraction) was placed between two glass wool plugs with a bed length of 10-20 mm. For the oxidation of CO and H2, a standard gas containing 1 vol% CO or H2 in air was dried in a silica gel column cooled down to 0°C or -77° C and passed through the catalyst bed at a space velocity of 20,000 h-iml/g-cat.. For the partial... 

The catalytic activity measurements were performed in a fixed bed reactor at 693 K. The gas flow composition was isobutene /O2/He = 1/ 2/ 7 (vol.) with a total flow of 30 mimin 1. The masses of catalysts used were so that the area developed by each phase (when present) in the reactor was ii entical when tested alone and in the mixture namely, 150 mg of BiP04 (i.e. 0.716 m+), 1039 mg of M0O3 (i.e. 0.730 m ) for the tests with the pure phases and 1189 mg of mechanical mixture (i.e. 150 mg or 0.716 m of BiP04 mixed with 1039 mg or 0.730 m of M0O3). In order... 

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