Hydrogen concentration and

The overall study showed that the rate of reaction has a first order dependence on both hydrogen concentration and total [Ir] (up to certain limiting hydrogen and catalyst concentrations) and an inverse dependence on the nitrile concentration. The observed kinetic dependence of the pseudo first order rate constant (k ) for the hydrogenation of C=C in NBR may be summarized by the expression show in Equation (1). 

The kinetic investigation of this reaction reveals the reaction is first-order in substrate, catalyst and hydrogen concentration, and thus yields the rate law r=kCat[Os][alkyne][H2]. The proposed mechanism as given in Scheme 14.6 is based on the rate law and the coordination chemistry observed with these osmium complexes. 

In the case of BDPP with a bite angle of 90°, the high-pressure NMR and high-pressure IR studies showed the structures of the hydrido dicarbonyl diphosphine resting state as an axial-equatorial BPT. Similar behavior was observed for the furanoside diphosphines. Dinuclear rhodium species in equilibrium with the mononuclear pentacoordinate rhodium hydride carbonyl diphosphines have been found for these ligands. The position of this equilibrium depends on the hydrogen concentration and the ligands. The rate... 

The presence of 4e as the predominant species during the catalysis is also in accord with the observed kinetic behavior of this catalyst with 1-octene and styrene as the substrates. The observation of this saturated acyl rhodium complex is in line with the positive dependence of the reaction rate on the hydrogen concentration and the zero order in alkene concentration. It was concluded previously that this saturated acyl complex is an unreactive resting state [18]. Before the final hydro-genolysis reaction step can occur, a CO molecule has to dissociate in order to form... 

However, reproducibility of lower limit results has been poor, owing principally to changes in the nature of the surface, so that Equation 54 cannot be regarded as accurate. For certain mixture compositions, the first limit pressure is independent of hydrogen concentration and is dependent solely upon oxygen concentration, as Equation 53 would predict... 

The dependencies both between the hydrogen concentration and the number of the microcracks emerged, and the values of velocity SAW on depth of the hydrogen penetration into the sample, period of diffusion, etc. are received at that. The limit hydrogen concentration in this material can be evaluated concerning the value of velocity SAW from the received dependence for steel (Fig. 4). 

The study of the role of surface hydrogen concentration and that of the OH group of cinchonidine indicates, that (i) the nature of enantiodifferentiation in the hydrogenation of trifluoromethyl ketones and a-ketoesters is partly different, and (ii) concerning the reactant-modifier interaction there are important differences also among the various trifluoromethyl ketones. 

According to the data on the dependence of molecular mass vs. monomer and hydrogen concentration and have been estimated by Eq. (VII) (Table 11). 

Dependence on hydrogen. When we examine runs 7, 8, and 9 in Table 10-5, we see that the rate increases linearly with increasing hydrogen concentration and we conclude that the reaction is first-order in H2. In light of this fact, hydrogen is either not adsorbed on the siuface or it s coverage of the surface is extremely low (1 ) for the pres-... 

Zirconium hydride is not a tme compound of fixed stoichiometry but rather a series of crystalline phases through which zirconium metal transforms with changing hydrogen concentration and temperature. The y-phase hydride exists below 250°C in the narrow composition range ZrH.Qg to ZrH the 5-phase has a compositional range Zftl to ZrH and the S-phase has a compositional range ZrH g—Z1H2. Most commercial hydride powder contains 5- and S-phase. 

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