Carbon monoxide energy decomposition

Decomposition. Acetaldehyde decomposes at temperatures above 400°C, forming principally methane and carbon monoxide [630-08-0]. The activation energy of the pyrolysis reaction is 97.7 kj/mol (408.8 kcal/mol) (27). There have been many investigations of the photolytic and radical-induced decomposition of acetaldehyde and deuterated acetaldehyde (28—30). 

Terephthalic Acid from Toluene. Both carbon monoxide and methanol can react with toluene to yield intermediates that can be oxidized to terephthalic acid. In work conducted mainly by Mitsubishi Gas Chemical Company (62,63), toluene reacts with carbon monoxide and molar excesses of HF and BF3 to yield a jtanz-tolualdehyde—HF—BF3 complex. Decomposition of this complex under carefully controlled conditions recovers HF and BF3 for recycle and ra-tolualdehyde, which can be oxidized in place of para-xyiene to yield terephthalic acid. One drawback of the process is the energy-intensive, and therefore high cost, decomplexing step. The need for corrosion-resistant materials for construction and the need for extra design features to handle the relatively hazardous HF and BF3 also add to the cost. This process can be advantageous where toluene is available and xylenes are in short supply. 

Carbon dioxide and hydrogen also interact with the formation of surface formate. This was documented for ZnO by the IR investigation of Ueno et al. (117) and, less directly, by coadsorption-thermal decomposition study (84). Surface complex was formed from C02 with H2 at temperatures above 180°C, which decomposed at 300°C with the evolution of carbon monoxide and hydrogen at the ratio CO Hs 1 1. When carbon dioxide and hydrogen were adsorbed separately, the C02 and H2 desorption temperatures were different, indicating conclusively that a surface complex was formed from C02 and H2. A complex with the same decomposition temperature was obtained upon adsorption of formaldehyde and methanol. Based upon the observed stoichiometry of decomposition products and upon earlier reported IR spectra of C02 + H2 coadsorbates, this complex was identified as surface formate. Table XVI compares the thermal decomposition peak temperatures and activation energies, product composition, and surface... 

Photodecomposition. Since the last review of photochemistry of HFA (61), there has been a great deal of effort expended in the study of the primary processes and decomposition modes of HFA. The photodecomposition products observed appear to be carbon monoxide and hexafluoroethane exclusively. The trifluoroacetyl radical, CF3CO, must be very unstable. As in acetone, it has been proposed that the decomposition processes must overcome an energy barrier, as temperature-dependent quantum yields were observed (252). A detailed mechanism that takes into account a vibrational deactivation cascade has been proposed by several authors (34,35,97,252). 

Decomposition of carbon monoxide takes place when it is exposed to radiation of wavelength 1,295 A, but not when exposed to 1,470 A -0. Herzberg2i5 has concluded from this that Z)(CO)<9-57 eV, but Gaydont< 6 has pointed out that when vibrational and rotational energy are taken into account the upper limit may be as high as 10 1 eV, and further that it is not established that photodissociation is the primary act in the reaction. 

Trifluoroacetic acid at 300-390 °C produces mainly carbon dioxide, difluoro-methyl trifluoroacetate, carbon monoxide and trifluoroacetyl fluoride. Blake and Pritchard propose that the decomposition proceeds through the elimination of hydrogen fluoride, followed by the formation of difluorocarbene which largely adds to trifluoroacetic acid to form the difluoromethyl ester. The kinetic order is about 0.5 and the overall activation energy for the formation of carbon dioxide and the difluoromethyl ester is about 45 kcal.mole" ... 

Transition metal oxalates. From studies of the decompositions of six oxalates (Mn, Fe, Co, Ni, Cu and Zn) Kornienko [146] concluded that the initial reaction product is the oxide and that for four of these salts (Fe, Co, Ni and Cu) the oxides are subseqently reduced to the metal by carbon monoxide. The values of the activation energies for these decompositions are comparable (about 176 kJ mol ) and stability is attributed to the polarizing power of the cation. Extensions of this approach to include salts of other cations have been discussed by Dollimore et al. [47] and Kadlec and Danes [55]. 

Derivation (1) Reaction of steam with natural gas (steam reforming) and subsequent purification (2) partial oxidation of hydrocarbons to carbon monoxide and interaction of carbon monoxide and steam (3) gasification of coal (see Note 1) (4) dissociation of ammonia (5) thermal or catalytic decomposition of hydrocarbon gases (6) catalytic reforming of naphtha (7) reaction of iron and steam (8) catalytic reaction of methanol and steam (9) electrolysis of water (see Note 2). In view of the importance of hydrogen as a major energy source of the future, development of the most promising of these methods may be expected. 

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