Water catalytic decomposition

Manganese(IV) oxide is a dark-brown solid, insoluble in water and dilute acids. Its catalytic decomposition of potassium chlor-ate(V) and hydrogen peroxide has already been mentioned. It dissolves slowly in alkalis to form manganates(lW), but the constitution of these is uncertain. It dissolves in ice-cold concentrated hydrochloric acid forming the complex octahedral hexachloromangan-ate(IV) ion ... 

Concentration Effects. The reactivity of ethyl alcohol—water mixtures has been correlated with three distinct alcohol concentration ranges (35,36). For example, the chromium trioxide oxidation of ethyl alcohol (37), the catalytic decomposition of hydrogen peroxide (38), and the sensitivities of coUoidal particles to coagulation (39) are characteristic for ethyl alcohol concentrations of 25—30%, 40—60%, and above 60% alcohol, respectively. The effect of various catalysts also differs for different alcohol concentrations (35). 

Release of enough energy dining catalytic decomposition of 65% peroxide to evaporate all water present and formed, and subsequent liability of ignition of combustible materials. 

Spillage of a weak (5%) aqueous peroxide solution onto cotton waste led, after some time, to ignition. This probably involved concentration of the peroxide by evaporation/absorption of the water, the heat insulating effect of the fibrous mass preventing heat loss as oxidation proceeded, and possibly the presence of trace metals in the waste promoting catalytic decomposition. 

A catalytic decomposition of triphenylphosphine has been reported [38] in a reaction involving rhodium carbonyls, formaldehyde, water, and carbon monoxide. The following reactions may be involved (Figure 2.39) ... 

Our approach utilized the metals gold, platinum, then later gold, platinum, and nickel electroplated in succession because the catalytic decomposition of hydrogen peroxide reaction we tested was most efficiently catalyzed with platinum.After fabrication of the nanowires they were freed by removing the conductive silver backing with nitric acid and the sacrificial template with a strong base, sodium hydroxide. Then nanorods were washed with deionized water and ultracentrifuged to achieve a neutral pH. 

Considerable attention has been given recently to the direct recovery of the hydrogen from hydrogen sulphide rather than conversion to water. Catalytic thermal cracking of H2S is possible (15,16) and improved catalysts permitting thermal decomposition at lower temperatures are being investigated. 

In general, dehydration means loss of water molecules from chemical substances, irrespective of their structure. Even if all cases where water is bonded in hydrate form are excluded, a number of reactions remain which also include formation of nitriles from amides, lactones from hydroxy acids etc. However, the present treatment will concentrate on the heterogeneous catalytic decomposition of alcohols in the vapour phase, which can be either olefin-forming or ether-forming reactions, and on the related dehydration of ethers to olefins. 

Kummer [19], Friedman and Biegeleisen [20] studied the decomposition of ammonium nitrate labelled withI5N [15N]H4 [14N]03. The completely anhydrous salt did not decompose until 300°C. Only sublimation took place. But a trace of water initiated decomposition at 180°C. The main products of the reaction were NzO and water (according to the eqn. (4)) and with the labelled salt, nitrous oxide [14N] [15N]0 was produced showing that the gas was formed by the interaction of the two ions in the molecule. They also showed that with ordinary ammonium nitrate and H2180, no N2I80 was formed, indicating that the water had a purely catalytic effect. 

Oxygen is the most abundant element in the earth s crust. Dioxygen (O2) can be prepared in the laboratory by electrolysis of water, by catalytic decomposition of hydrogen peroxide, or by thermal decomposition of KCIO3. Oxygen is manufactured by fractional distillation of liquefied air and is used in making steel. The O2 molecule is paramagnetic and has an... 

Recently, interesting effects of NO and water on the formation and properties of a-oxygen were discovered. Even small amounts of NO facilitated desorption of Oa from the surface, strongly increasing the rate of catalytic decomposition of N20 to the... 

Since general acid catalysis of reaction (19) had been observed8, the terms in [I-] and [I-]2, in equation (22) might be due to water-catalysed decompositions of the complexes CH2-CHCH2HgI2 and CH2 CHCH2HgI32. However, it was felt that the catalytic constants in equation (22) were much too large for this to... 

Huang H-H, Lu M-C, Chen J-N. Catalytic decomposition of hydrogen peroxide and 2-chlorophenol with iron oxides. Water Res 2001 35 2291-2299. 

Direct catalytic decomposition of water ( thermo-physical cycle ) ... 

Hwang, G.J. and Onuki, K., Simulation study ou the catalytic decomposition of hydrogen iodide in a membrane reactor with a silica membrane for the thermochemical water splitting IS process. Journal of Membrane Science, 194, 207, 2001. 

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