The elimination of chlorines in catalyst

The reaction enthalpy and Gibbs free energy at different temperatures of the above reaction are listed in Table 6.25. It is seen from Table 6.25 that AH is less than 0, which illustrates that the reduction of RuCla is an exothermic reaction and the equilibrium constant decreases with temperature. Therefore, low temperature is beneficial for the reaction equilibrium moving forward. However, the equilibrium constant is very high even at temperatures as high as 1,000 K. 

This indicates that the reaction of (6.14) easily happens in thermodynamics. For both thermodynamics and kinetics, temperature has two opposite roles on the reaction of RuCls reduction. Therefore, there is an optimum temperature for the reduction. 

The experimental results show that pure RuCla begins to be reduced at 175°C and finishes at about 200° C. But due to the interactions between RuCla and supports, the reduction temperatures will be different when we use the different supports. The reduction temperatures of the RuCla supported on activated carbons are different with each other in literature,154,155 the temperatures range 

R is seen from Fig. 6.35 that the catalyst reduced at 200°C has the highest activity. R cannot be reduced completely when the temperature is lower than 200° C. The change of temperature is not the significant effect on the catalyst activity when the temperature is in the range of 200°C-300°C. The activity is obviously decreased when the temperature is over 300°C. d4i,is6 illuminated the dechlorination effect, the best when the temperature is about 200°C. 

The efficiency of H2 reduction method depends on the removal of the retained chlorines because HCl produced during the reduction process of the catalyst can be adsorbed once again so that the chlorines cannot be completely removed, even though the reduction reaction is complete. 

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H2 reduction method. The elimination of chlorines in catalyst is an important role and step during the preparation of ruthenium catalyst. In order to eliminate the Cl in activated carbon supported ruthenium catalyst prepared using RuClg as the precursors, it is necessary that RuCla is reduced to elementary ruthenium and... 

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