Hydrogen from thermal decomposition

As in the case for adsorbed but-l-ene on Pt/Si02, the broad absorption at 1600 cm-1 in Fig. 25A is attributed to the presence of chemisorbed bridged hydrogen. It intensifies on heating up to above 473 K, and this would be consistent with additional surface hydrogen from thermal decomposition of the hydrocarbon species. At the same time, the alkyl absorptions become weaker and broader while a broad absorption from v=CH and/or v=CH2 grows to become the strongest spectral feature at 573 K. 

Diimide diimine, diazene), N2H2 or HN=NH, is an ephemeral species which results from decomposition with acids of potassium azodicarboxylate [264, 265] from thermal decomposition of anthracene-9,10-diimine [266, 267], and of hydrazine [268,269] and its derivatives [270]. Although this species has not been isolated, its transient existence has been proven by mass spectroscopy and by its reactions in which it hydrogenates organic compounds with concomitant evolution of nitrogen [271]. 

Primary alcohols in particular give an M — 18 peak due to loss of water from the molecular ion although this peak may partly arise from thermal decomposition of the alcohol in the ion source. Initial migration of a hydrogen on the alkyl chain is followed by cleavage of the carbon-oxygen bond, see, for example, the spectrum of propan-l-ol, Fig. 3.81, which shows strong peaks at m/z 59, 42, 31... 

R CHORj. Such radicals have been formed by hydrogen atom abstraction from the ether by radicals produced from thermal decomposition of peroxides (67, 75, 76). Similar radicals may be produced in photochemical processes, either by direct irradiation (29, 54), or by the use of a photosensitizer or a photoinitiator, such as acetone or benzophenone (21, 64, 66). The ether radicals once produced, participate in a variety of chemical reactions. It might be noted that resonance forms as illustrated... 

We successfully demonstrated that hydrogen could be efficiently produced by catalytic steam reforming of carbohydrate-derived bio-oil fractions in a fluidized bed reactor using a commercial nickel-based catalyst. Greater steam excess than that used for natural gas reforming was necessary to minimize the formation of char and coke (or to gasify these carbonaceous solids) resulting from thermal decomposition of complex carbohydrate-derived compounds. 

The formation of hydrocarbons from thermal decomposition of formic acid at room pressure and high temperature (1696 K) has been reported by Muller et al. [142]. In our study we also find evidence of hydrocarbons and note how their spectral features depend on reaction conditions. At 3 GPa and room temperature, the nature of O-H bonds from formic acid become more covalent-like with increasing temperature. Once a reaction occurs the long-range order of the O-H network in crystalline formic acid becomes disrupted with bond distances increasing to a more hydrogen-like bond length centered at frequency of approximately 3500 cm" . 

Since each of these catalyst systems was expected to proceed via intermediate formation of a metal hydride anion (from 3) and protonation to a neutral dihydrogen metal species, then in the absence of any olefin, each could be expected to produce molecular hydrogen upon thermal decomposition. That is, each also should be a catalyst for the water gas shift reaction (Reaction 7). Such was found to be the case in the... 

Hydrogen sulfide conversions of up to 62 mL min i were obtained at 900 °C with a 40% H2S stream flowing at 200 mL mimL This corresponded to an equivalent current density of 710 mA cm and close to 550% removal beyond that expected from thermodynamic hydrogen sulfide thermal decomposition at this... 

We have examined a number of materials in terms of toxic gas evolution during pyrolysis or combustion. For example, the products from fibreglass insulations included isocyanic acid and hydrogen cyanide, while the support backing and adhesive of a made-up panel produced acetic acid, acetaldehyde and vinyl chloride as well. The effect of a fire in a confined space such as a surface ship or submarine can be imagined. The products come from thermal decomposition of polymer coatings etc, and while the experimental conditions may not duplicate those of a fire, the information is very useful. 

Al-Shamma LM, Naman SA (1990) The production and separation of hydrogen and sulfur from thermal decomposition of hydrogen sulphide over vanadium oxide/sulphide catalysts. Int J Hydrogen Energy 15(1) 1-15... 

Here, two conclusions are important from this mechanism derived from metallurgical samples of magnetite/wiistite synthetic mixtures. First, the elemental iron is essential to reduce magnetite with hydrogen gas at low temperature. This elemental iron is produced from thermal decomposition of the wiistite mixture in the precursor. Stability and bulk distribution of the wiistite determine the abundance of reaction interfaces in the polycrystalline solid. The grain structure and porosity of the final catalyst is mainly predetermined by the disposition of these reaction centers representing the nuclei of the iron metal crystallines. Second, the reaction involves movement of all iron ions and allows a complete bulk restructuring of the solid at low temperature. The topochemistry of the reduction process will determine... 

From different ways of the preparation of this electrode [92-94], the method of anodization of a silver plate (wire) or silver deposited on a Pt support in sulfide solution is advised. Also the platinum support covered by porous silver (prepared from thermal decomposition of silver oxide paste) placed into aqueous solution of hydrogen sulfide led to the formation of the Ag Ag2S system. 

Tetraalkylphosphonium chlorides are known to catalyze the dehydrohalogenative coupling reaction of alkyl chlorides with trichlorosilanes (Scheme 3-18). " A plausible catalytic cycle is proposed to involve a trichlorosilyl anion that is produced through pentacoordinated hydrido(tetrachloro)silicate species, which loses hydrogen chloride at high temperature. Alternative pathway may involve dichlorosilylene derived from thermal decomposition of trichlorosilyl anion. Inserstion of dichlorosilylene into C-Cl bonds gives the products. Because the coproduced HCl escapes from the reaction mixture, the reaction proceeds smoothly. 

Tellurium trioxide, TeOa, is an orange yellow powder made by thermal decomposition of telluric(VI) acid Te(OH)g. It is a strong oxidising agent which will, like H2Se04, oxidise hydrogen chloride to chlorine. It dissolves in hot water to give telluric(VI) acid. This is a weak acid and quite different from sulphuric and selenic acids. Two series of salts are known. 

Classical chemiluminescence from lucigenin (20) is obtained from its reaction with hydrogen peroxide in water at a pH of about 10 Qc is reported to be about 0.5% based on lucigenin, but 1.6% based on the product A/-methylacridone which is formed in low yield (46). Lucigenin dioxetane (17) has been prepared by singlet oxygen addition to an electron-rich olefin (16) at low temperature (47). Thermal decomposition of (17) gives of 1.6% (47). 

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