Decomposition of H2O, NO*, and

The decomposition of H2S, NO, and NH3 the breakdown of pollutants and volatile organics to CO2 and H2O photocatalytic reactions involving Ti02 as both catalyst and membrane methanol reforming for the production of H2, as well as direct... 

Catalysts include oxides, mixed oxides (perovskites) and zeolites [3]. The latter, transition metal ion-exchanged systems, have been shown to exhibit high activities for the decomposition reaction [4-9]. Most studies deal with Fe-zeolites [5-8,10,11], but also Co- and Cu-systems exhibit high activities [4,5]. Especially ZSM-5 catalysts are quite active [3]. Detailed kinetic studies, and those accounting for the influence of other components that may be present, like O2, H2O, NO and SO2, have hardly been reported. For Fe-zeolites mainly a first order in N2O and a zero order in O2 is reported [7,8], although also a positive influence of O2 has been found [11]. Mechanistic studies mainly concern Fe-systems, too [5,7,8,10]. Generally, the reaction can be described by an oxidation of active sites, followed by a removal of the deposited oxygen, either by N2O itself or by recombination, eqs. (2)-(4). 

As previously said, water does not inhibit the formation of species I at high temperatures (where species I can be formed by decomposition of species III), and this agrees with the absence of any detectable effects of water in the formation of NO by ammonia oxidation. According to the above mechanism, it is also expected that the reaction NO + NH3 will not be affected by the presence of H2O. In previous work it was found that water inhibits the SCR reaction on metal oxide based catalysts [2,16], but to a lower extent in comparison with ammonia oxidation. However, the SCR reaction occurs at lower temperatures with respect to ammonia oxidation to NO, so that at these conditions species III and species I are still in competition. 

Nitrocellulose is among the least stable of common explosives. At 125°C it decomposes autocatalyticaHy to CO, CO2, H2O, N2, and NO, primarily as a result of hydrolysis of the ester and intermolecular oxidation of the anhydroglucose rings. At 50°C the rate of decomposition of purified nitrocellulose is about 4.5 x 10 %/h, increasing by a factor of about 3.5 for each 10°C rise in temperature. Many values have been reported for the activation energy, E, and Arrhenius frequency factor, Z, of nitrocellulose. Typical values foiE and Z are 205 kj/mol (49 kcal/mol) and 10.21, respectively. The addition of... 

Barium nitrite [13465-94-6] Ba(N02)2, crystallines from aqueous solution as barium nitrite monohydrate [7787-38-4], Ba(N02)2 H2O, which has yellowish hexagonal crystals, sp gr 3.173, solubihty 54.8 g Ba(NO2)2/100 g H2O at 0°C, 319 g at 100°C. The monohydrate loses its water of crystallization at 116°C. Anhydrous barium nitrite, sp gr 3.234, melts at 267°C and decomposes at 270 °C into BaO, NO, and N2. Barium nitrite may be prepared by crystallization from a solution of equivalent quantities of barium chloride and sodium nitrite, by thermal decomposition of barium nitrate in an atmosphere of NO, or by treating barium hydroxide or barium carbonate with the gaseous oxidiation products of ammonia. It has been used in diazotization reactions. 

Calcium hexacyanoferrate (II) (IIH2O) [ 13821 -08-4] M 490.3. Recrystd three times from conductivity H2O and air dried to constant weight over partially dehydrated salt. [Trans Faraday Soc 45 855 1949.] Alternatively the Ca salt can be purified by pptn with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous soln. The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24h, then over partly dehydrated salt and stored in a dark glass stoppered bottle. No deterioration occurred after 18 months. No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with cone H2SO4. Analyses indicate 1 Imols of H2O per mol of salt. The solubility in H2O is 36.45g (24.9 ) and 64.7g (44.7 ) per lOOg of solution. [J Chem Soc 50 1926.]... 

Comparative kinetic and in-situ DRIFT studies of the N2O decomposition over Co-, Fe- and Cu-ZSM-5 have been performed. The implications of the presence of O2, CO, NO, H2O and SO2 on the catalyst activity and stabilitiy and on the mechanism are evaluated. 

Conditions. The influence of temperature, partial N2O and O2 pressure, space time W7Fn2o. and gases like H2O, SO2, CO and NO on the decomposition of N2O over the catalysts were studied. The temperatures varied between 625 to 873 K. The inlet partial N2O pressure ranged from 0.05 to 0.2 kPa, the O2 pressure from 0 to 10 kPa and the space time from 1.5x10 to ll.OxlO g s/mol. The total gas flowrates were between 1 and 5 ml(STP)/s. NO, CO or SO2 were added in molar ratios of 0-2 with N2O (at 0.1 kPa). The H2O pressure amounted to 13.6 kPa by passing the feed gas through a saturator kept isothermal by means of a water bath. 

One additional problem at semiconductor/liquid electrolyte interfaces is the redox decomposition of the semiconductor itself.(24) Upon Illumination to create e- - h+ pairs, for example, all n-type semiconductor photoanodes are thermodynamically unstable with respect to anodic decomposition when immersed in the liquid electrolyte. This means that the oxidizing power of the photogenerated oxidizing equivalents (h+,s) is sufficiently great that the semiconductor can be destroyed. This thermodynamic instability 1s obviously a practical concern for photoanodes, since the kinetics for the anodic decomposition are often quite good. Indeed, no non-oxide n-type semiconductor has been demonstrated to be capable of evolving O2 from H2O (without surface modification), the anodic decomposition always dominates as in equations (6) and (7) for... 

Aqueous solutions of ammonium sulfate and ammonium bisulfate were deposited on Fluoropore filters, placed in the direct insertion probe, and analyzed in the chemical ionization mode (H2O reagent) gas. The samples were heated from 100°C to 330 C at 15 C/minute. No sample ions were observed under these anlaysis conditions, even when several micrograms of ammonium salts were analyzed. The thermal decomposition of ammonium salts of sulfate has been the subject of many studies. (29,30) Some pathways include sulfuric acid production at one stage of the decomposition while others suggest ammonia, SO2 and SO3 are the products. None of these accurately simulate the conditions (temperature, pressure, gas flow) present in our chemical ionization source. However, no sulfuric acid ions (H3SO4+, etc.) were ob-served... 

From the discussion in the previous section, it is clear that, above all, NO2, and then NO, are the principal oxidizers produced in the flames of nitrate esters. The reaction of NO2 with aldehydes plays an important role in the combustion of nitrate esters, since these molecules are the major decomposition products of these materials in the first stage of combustion. Pollard and Wyatt studied the combustion process of HCHO/NO2 mixtures at sub-atmospheric pressures.They found that the reaction occurs very rapidly at temperatures above 433 K, the NO2 being reduced almost quantitatively to NO, and the aldehyde being oxidized to CO, COj, and H2O. The order of reaction was found to be one with respect to both reactants. The same result has been reported by McDowell and Thomas.I ] jgg proposed reaction steps are ... 

DSC and DTA measurements show melting of ADN, NH4N(N02)2, at 328 K, the onset of decomposition at 421 K, and an exothermic peak at 457 K.[27] Gasification of 30% of the mass of ADN occurs below the exothermic peak temperature, and the remaining 70% decomposes after the peak temperature. The decomposition is initiated by dissociation into ammonia and hydrogen dinitramide. The hydrogen dinitramide further decomposes to ammonium nitrate and N2O. The final decomposition products in the temperature range 400-500 K are NH3, H2O, NO,... 

From the very good activity of thermally or electrochemically activated CoTAA for the reaction of CO one might deduce that the oxidation of formic or oxalic acid proceeds, not directly, but by way of a preliminary decarbonylization reaction. However, there is no evolution of gas from CoTAA in a solution of formic acid in dilute sulfuric acid, even at 70 °C. Such a reaction would have to occur on chemical decomposition of formic acid, with evolution of CO and H2O, or CO2 and H2. It may thus be assumed that formic acid is oxidized directly. 

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