Acetic acid decomposition

Fig. 3 gives the conversions for acetic acid and ammonia decomposition over Ti02 and Al-Ti02 in a three-phase fluidized photoreactor. In the case of acetic acid decomposition (Inlet condition of 300 ppm), the conversion increased with alununum addition. In particular, the conversion to CO2 reached about 90% and then it was kept until 600 mins on Al-TiOa catalyst. On the other hand, in b), the anunonia removal (Inlet condition of 80ppm) also enhanced on Al-Ti02 compared to that conventional Ti02 catalyst the conversion to N2 reached above 95% in Al-Ti02. We have also observed that the ammonia conversion in a conventional batch type steady photoreactor could be obtained up to 70%. From this result, we could confirmed that... 

Fig.3. Decomposition of acetic acid and ammonia over Ti02 and AI-Ti02 in three-phase fluidized photocatalytic system, a) For acetic acid decomposition and b) For ammonia decomposition...

Acetaldehyde thus formed is oxidized in situ to acetic acid. Decomposition may also take place through other pathways. Ethyl alcohol can be an important primary product which cooxidizes rapidly.870 871... 

Two homogeneous metal complex water-gas shift catalyst systems have recently appeared 98, 99). The more active of these comes from our Rochester laboratory (99, 99a). It is composed of rhodium carbonyl iodide under CO in an acetic acid solution of hydriodic acid and water. The catalyst system is active at less than 95°C and less than 1 atm CO pressure. Catalysis of the water-gas shift reaction has been unequivocally established by monitoring the CO reactant and the H2 and C02 products by gas chromatography The amount of CO consumed matches closely with the amounts of H2 and C02 product evolved throughout the reaction (99). Mass spectrometry confirms the identity of the C02 and H2 products. The reaction conditions have not yet been optimized, but efficiencies of 9 cycles/day have been recorded at 90°C under 0.5 atm of CO. Appropriate control experiments have been carried out, and have established the necessity of both strong acid and iodide. In addition, a reaction carried out with labeled 13CO yielded the same amount of label in the C02 product, ruling out any possible contribution of acetic acid decomposition to C02 production (99). 

The formic ° and acetic acid decompositions are probably not unimolecular, intramolecular eliminations as reported. An. 4-factor lower than 10 sec (Table 38, HCOOH-> H2 + CO2) is quite impossible. In addition, decomposition of formic acid dimer, (HCOOH)2 - 2H2O + CO, is equally suspect. The authors... 

At temperatures greater than a 100°C, thermal degradation of carboxylic acids produces methane and carbon dioxide (Surdam et ai, 1984). As the carboxylic acid anions are consumed due to increasing temperature, the carbonate system becomes internally buffered, and thus the pH may decrease due to increased in the system, leading to carbonate dissolution and the enhancement of secondary porosity (Surdam et ai, 1984). Factors influencing the thermal destruction rate of organic acids include coupled sulphate reduction and hydrocarbon oxidation, and the mineralogy of host sediments (Bell, 1991) the presence of hematite causes rapid rates of acetic acid decomposition. 

The formation of methanol in the catalytic decomposition of acetic acid has not been reported. This is somewhat to be expected since it is probable that methanol would be unstable at the temperatures required for the acetic acid decomposition. However, catalysts which direct the decomposition to hydrogen and carbon monoxide have not been reported, and no basis is to be had regarding the efficacy of the numerous substances that liave been patented for the synthesis. 

Finally, the CH2OH radicals react with O2 to give HCHO and HO2 (5.327). Thus, C2 is broken down into Ci species. Fig. 5.34 shows schematically the C2 gas phase chemistry. It is obvious that there is no ethanol formation and acetic acid decomposition, whereas acetaldehyde provides many pathways back to Ci chemistry. Glycolaldehyde is a highly water-soluble product from several C2 species (ethene, acetaldehyde and ethanol) other bicarbonyls, however, are likely to be produced preferably in solution. The aqueous phase produces other C2 speeies but also deeomposes them (Fig. 5.35). By contrast, in aqueous solution from Ci, C2 species can be given as shown by the formation of glyoxal from the formyl radicals (5.351) the latter is... 

If, after the nitrogen molecule has been ejected, the p orbital of the cation and the counter ion are not aligned for orbital overlap, some rotation of the cation will be required for bonding. In some cases, sufficient rotation will occur so that bond formation can occur on what was the back side of the cation thus the intramolecular inversion observed in the nitrosoamide decomposition and the nitrous add deamination can be accounted for at this stage in the reaction. This interpretation also accounts for the fact that in the acetic acid decomposition of the tolyltriazene of 1-phenylethylamine, the reaction of the cation with tolylamine proceeds with more retention of configuration than the reaction of the cation with the add anion that is, the position of the counter ion with respect to the cation determines the overall stereospecificity (section b). 

PolymerizationICondensation Reactions. Immiscible oils were observed on opening autoclaves at the end of acetic acid decomposition experiments that... 

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