Deacon reaction

Deacon equilibrium Deacon process Deacon reaction Deactivating groups Deactivation... 

The Weldon-Pechiney process for manufacturing CI2 from HCl involves the use of Mn02 as the oxidizing agent instead of the O2 employed in the Deacon reaction. 

Chlorine may be formed by the Deacon reaction at temperatures below about 900°C,... 

As we have seen before, use of intermediate oxychloride is very problematic, because it can only be produced with a large over-stoichiometry of H20 and only at low pressure. An alternative is to try to directly decompose CuCl2 at high pressure and use the reverse Deacon reaction ... 

The reverse Deacon reaction is usually conducted at high temperature over 600°C, but can be handled at 500°C or even lower using an H20 over-stoichiometry. Also CuCl2 decomposition should usually be performed at a temperature over 600°C, but if Cl2 is removed by the reverse Deacon reaction, the temperature can be lowered to 500°C or less. 

The main differences between the models lies in whether or not some fraction of the catalyst is in direct contact with the bubble gas, and in the extent of axial mixing in each phase. Properties of various models have been discussed extensively by Gilliland and Knudsen (G7) in relation to the extent of reaction in experimental fluidized bed reactors, considering that allowance for direct contact between bubble gas and a certain amount of catalyst in it is the sole way to account for the contact efficiency. Unless a fraction of the catalyst particles is assumed to be entrained in the bubble gas, the bubble size calculated to fit the reaction data is found to decrease with increasing catalyst activity at otherwise identical fluidization conditions, in which the bubble size should remain constant. Essentially the same decrease in bubble size was observed by Miyauchi and Morooka (M29) in their analysis of the data by Lewis et al. (LI 2), and by Furusaki (F14) in his fluidized bed data for the Deacon reaction. 

The successive contact model seems to be sound in accounting for the fluid-bed performance given in Fig. 68, since the model satisfies the flow and transport properties of the beds as well. The model is also applied successfully to catalytic oxidation of HCl (the Deacon reaction) in a fluid bed (FI4). 

Apart from the ANL s current effort on Hybrid Cu-Cl Cycle, there have been only a limited number of other processes proposed for moderate temperature thermochemical hydrogen production. Dokiya and Kotera [3] proposed a cycle with a significant variant of the Hybrid Cu-Cl Cycle involving a direct electrochemical hydrogen generation reaction. More recently, Simpson et al. [4] have proposed a hybrid thermochemical electrolytic process for hydrogen production based on modified Reverse Deacon Reaction (generation of HCl gas) and gas phase electrolysis of HCl. 

The first reaction is the electrolysis step conducted at room temperature and the second step, which involves reaction of solid CuCl2 with steam at around 600°C, closes the cycle. As can be seen, a single step of Equation (4) combines Steps 4 and 5 of the ANL s cycle presented in Table 1. The reaction given in Equation (4) may be expressed more precisely in two steps as shown in Equations (5) and (6). Equation (6) is known as the Reverse Deacon Reaction. 

Hybrid Thermochemical Electrolytic Process for Hydrogen Production Based on Modified Reverse Deacon Reaction... 

From preliminary efficiency estimates and proof of principle experiments, Simpson et al. [4] have recently proposed a hybrid process based on the reverse Deacon cycle as a promising moderate temperature thermochemical process to produce hydrogen. The basic reactions involved are shown in the three steps in Table 3. As can be seen from the equations given in Table 3, the two-step sequence involving magnesium chloride hydrolysis (Step 1) followed by magnesium oxide chlorination (Step 3) reduces to the Reverse Deacon Reaction. The moderate temperatures involved in these reactions would... 

Simpson et al. [4] propose to carryout the two-step Deacon reaction through supported magnesium compounds on a zeolite such as Silicalite. Though they have addressed many of the development requirements of this process, some still need considerable effort for assessment of the commercial viability of the overall process. Due to the lower temperature requirements of this process (compared to high temperature thermochemical processes), the less stringent demand on materials, and the well-established status of the electrolysis step, this process deserves further evaluation. 

M.F. Simpson, S.D. Herrmann and B.D. Boyle, A hybrid thermochemical electrolytic process for hydrogen production based on the reverse Deacon reaction, International Journal of Hydrogen Energy, in press December 2005. 

Hydrogen chloride may be used as a chlorinating agent. It is sometimes employed in such a manner that it adds to the double bond as in the preparation of ethyl chloride from ethylene 75 or in the synthesis of vinyl chloride from acetylene 16. Kainer 48 has surveyed the patents dealing with the preparation of vinyl chloride. A review 21 of the patent literature and the apphcation of the Deacon reaction, which uses hydrogen chloride and air, has also been published. Some of the material on this reaction has been mentioned before 26, 82, 61. ... 

It is known that the chlorination of ethane with chlorine formed in the oxidation of hydrogen chloride proceeds by a heterogeneous—homogeneous mechanism [3]. This is why the effieiency of cement catalysts was studied separately by the examples of Deacon reaction and dichloroethane dehydrochlorination reaction. 

Thus, the activity of copper—cement catalysts in Deacon reaction is comparable with that of commonly used salt catalysts. 

The main products of this reaction were CO2, CI2 and HCl, with trace amounts of CO and CCI4 produced across the temperature range. Between 275 and 400°C a linear relationship between the destruction of CHCI3 and the formation of CO2, CI2 and HCl was reported. Above this temperature, conversion of CHCI3 did not continue to increase at the same rate with temperature and neither did the production of HCl. In contrast, relative CI2 concentration increased and this observation is attributed to the Deacon reaction. 

This reaction is not consistent with the observed results, as negligible CI2 was produced, suggesting that the majority of CI2 was converted to HCl. As there is water in the effluent, it might be supposed that the Deacon reaction ... 

Solve the equilibrium calculations for the Deacon reaction in Example 6.6 at d = 70 ""C using the G-minimization technique. 

Addition of the two reactions shows the same stoichiometry as the Deacon reaction. Reaction (9) took place at 250-300°C and reaction (10) at 475-500°C. The Dow Chemical Company developed a two-stage moving-bed reactor in which Fc203 meets HCl in the upper section. FeCls falls into the lower section of the tower and is converted into the oxide by hot air or oxygen. The chlorine goes to separation and purification. 

Formation of CI2 can also be expected by the Deacon reaction due to the formation of HCl in the presence of a high oxygen concentration in the reaction environment. 

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