Quenching products, separation

A complex representation of IMPS data obtained for the heterogeneous quenching of ZnTPPC -diferrocenylethane is displayed in Fig. 21(a). The semicircular response in the first quadrant corresponds to the competition between product separation and back electron transfer, while the lower quadrant is determined by the i uQi constant. The i uQi attenuation limited the frequency range to less than 1 kHz. Equation (45) describes the experimental spectra at various Galvani potential differences [solid lines in Fig. 21(a)],... 

The construction of this reactor is relatively simple, except the requirements for isothermality and products quenching or separation. The cost is reasonable, but rapid catalyst-reactant separation or rapid quenching of the reaction is essential. Representative sampling may be a problem. 

Analysis of the reaction rates is achieved in terms of oxygen uptake measured with an oxygen electrode, or by product separation and quantification. DPBF absorbs intensely at 415 nm and reacts rapidly with singlet oxygen to form a colorless intermediate endoperoxide. The DPBF reaction can be used as a benchmark against which the effect of an added quencher is compared. A note of caution must be applied the use of inhibitors and quenchers alone is not unambiguous in its outcome and should be strictly supplemented with flash photolysis experiments. Thus, if a photosensitized reaction is quenched by millimolar concentrations of azide ion, it should also be established that azide does not quench the triplet state of the sensitizer directly because that would also affect the reaction rate. 

This endothermic plasma-chemical process was considered, in particular, to be an important step in the thermochemical calcium-bromine-water splitting cycle for hydrogen production (Doctor, 2000). The plasma-chemical HBr decomposition (5-182) assumes in this case effective quenching and separation of products by fast rotation of quasi-thermal plasma... 

This endothermic plasma-chemical process was considered in Section 5.11.1. The process requires super-ideal quenching and separation of the products by fast plasma rotation similar to the case of plasma-chemical H2S dissociation (see Sections 10.7.5 and 10.7.6, and Fig. 5-76). The plasma-chemical stage (10-94), using off-peak electricity, can be a key step in the following HBr cycles of hydrogen production from water. The first cycle, proposed by Parker and Clapper (2001), applies the bromine produced in plasma (10-94) for reaction with water ... 

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