Heterogeneous catalysis decomposition

Wagner was first to propose the use of solid electrolytes to measure in situ the thermodynamic activity of oxygen on metal catalysts.17 This led to the technique of solid electrolyte potentiometry.18 Huggins, Mason and Giir were the first to use solid electrolyte cells to carry out electrocatalytic reactions such as NO decomposition.19,20 The use of solid electrolyte cells for chemical cogeneration , that is, for the simultaneous production of electrical power and industrial chemicals, was first demonstrated in 1980.21 The first non-Faradaic enhancement in heterogeneous catalysis was reported in 1981 for the case of ethylene epoxidation on Ag electrodes,2 3 but it was only... 

The reverse micelles stabilized by SDS retard the autoxidation of ethylbenzene [27]. It was proved that the SDS micelles catalyze hydroperoxide decomposition without the formation of free radicals. The introduction of cyclohexanol and cyclohexanone in the system decreases the rate of hydroperoxide decay (ethylbenzene, 363 K, [SDS] = 10 3mol L [cyclohexanol] =0.03 mol L-1, and [cyclohexanone] = 0.01 mol L 1 [27]). Such an effect proves that the decay of MePhCHOOH proceeds in the layer of polar molecules surrounding the micelle. The addition of alcohol or ketone lowers the hydroperoxide concentration in such a layer and, therefore, retards hydroperoxide decomposition. The surfactant AOT apparently creates such a layer around water moleculesthat is very thick and creates difficulties for the penetration of hydroperoxide molecules close to polar water. The phenomenology of micellar catalysis is close to that of heterogeneous catalysis and inhibition (see Chapters 10 and 20). 

The slow, thermal decomposition of hydrazoic acid in a static system has been studied by Meyer and Schumacher58. It turned out to be completely governed by heterogeneous catalysis. There are no studies on the kinetics of the homogeneous decomposition of this substance save for the investigation of its decomposition flame59. From the variation of flame properties with pressure it can be deduced that second-order reactions control the over-all rate. The unimolecular reaction... 

Correlations between catalytic activity and a variety of bulk properties of semiconductors have been reported (i) the average band gap of III-V and II-VI semiconductors and activity towards hydrogenation of isopropanol (ii) enthalpy of oxides and their activity towards oxidation of propylene and (iii) number of d-electrons (and crystal field stabilization energy) or 3rf-metal oxides and their activity towards N2O decomposition. The last correlation, due to Dowden (1972), is important since it provides a connection between heterogeneous catalysis and coordination chemistry of transition-metal compounds. A correlation between the catalytic activity of transition-metal sulphides towards hydrodesulphurization of aromatic compounds and the position of the transition metal in the periodic table has been made by Whittingham ... 

Gas Phase. The decomposition of gaseous ozone is sensitive not only to homogeneous catalysis by light, trace organic matter, nitrogen oxides, mercury vapor, and peroxides, but also to heterogeneous catalysis by metals and metal oxides. 

To assess the generality of the decomposition solution method we have applied it to several arbitrary reaction orders, for example, n = 1.73, 0.67, -0.5, -1.0 etc.10,11 These reaction orders have been chosen to represent typical cases of kinetics in heterogeneous catalysis and electrocatalysis where adsorption phenomena play a major role. Values of effectiveness of a plane catalyst pellet for the different reaction orders are shown in Figure 5. Clearly all of the data for positive reaction orders show the expected trend of a decrease in effectiveness with increase in Thiele modulus. Effectiveness values determined for reaction... 

In heterogeneous catalysis, transition metal nanoparticles are supported on different substrates and are utilized as catalysts for different reactions [57], such as hydrogenations and enantioselective synthesis of organic compounds [58], oxidations and epoxidations [59], and reduction and decomposition [57],... 

M. Grunzel [ The Chemical Physics of Solid Surfaces and Heterogeneous Catalysis, Synthesis and Decomposition of Ammonia vol.4, Ed. D.A. King (Elsevier Scientific Publishing Company, Amsterdam, 1982)]... 

The decomposition of molten potassium azide has been shown to involve heterogeneous catalysis and induction periods which can be attributed to the presence of residual water in the melts. Homogeneous catalysis is of slight importance. 

Hence it has been concluded that the rate-determining step involves removal of the two phosphorus-bound protons. The energy of activation (24 kcal.mole ) decreases with increasing alkalinity, probably due only to a salt effect. The decomposition has also been examined in the presence of nickel and cobalt, which apparently introduce heterogeneous catalysis . 

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