Hydrogen-consuming reactions

Gas/vapor phase hydrogen-consuming reactions using dense membrane reacimrs 

Hydrogenation of 13 butadieneto butene (T=1000C) Hydrogenation of carbon monoxide to hydrocarbons (T=25(M10 C) 

Hydrogenation of Catalytic Pd (foil) Reaction rate is Nagamoto and 

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Propylene. Propylene alkylation produces a product that is rich in dimethylpentane and has a research octane typically in the range of 89—92. The HF catalyst tends to produce somewhat higher octane than does the H2SO4 catalyst because of the hydrogen-transfer reaction, which consumes additional isobutane and results in the production of trimethylpentane and propane. 

A fuel cell consists of an ion-conducting membrane (electrolyte) and two porous catalyst layers (electrodes) in contact with the membrane on either side. The hydrogen oxidation reaction at the anode of the fuel cell yields electrons, which are transported through an external circuit to reach the cathode. At the cathode, electrons are consumed in the oxygen reduction reaction. The circuit is completed by permeation of ions through the membrane. 

The thermograms of Cu reduction in silica-, alumina-, titania- and zirconia-supported catalysts show only one pe the maximum of which is reported in Table 3. The amount of hydrogen consumed by the r uction corresponds, within experimental error, to the theoretical amount required for the reaction ... 

The reaction of ADPA with acetone led to a solid product, presumably 4-(isopropylamino)diphenylamine (mp 72-76°C), with the hydrogen uptake leveling at 56 minutes. Since the product could not be analyzed by GC, the conversion was calculated from the amount of hydrogen consumed during the reaction. 

In the kinetic study, data were obtained from the amount of hydrogen consumed by the reaction over time using an automated gas uptake control system. The apparatus is designed to maintain isothermal and isobaric conditions while monitoring H2 consumption. Procedures used were as described previously.3"5... 

The pulse experiments demonstrated that active sites for propane dehydrogenation are formed upon exposure of the oxide form of gallium modified ZSM-5 to propane itself. A constant 1 1 ratio of hydrogen produced to propane consumed is attained after a number of pulses with little propene formation, which suggests that, after propane dehydrogenation to propane, aromatization proceeds through hydrogen transfer reactions. 

This reaction can only proceed if the electrons are consumed by a cathodic counter reaction, because otherwise the metal surface would accumulate charge. Common reactions are the hydrogen evolution reaction, which in acid solutions proceeds according to ... 

One problem encountered when monitoring gas-consuming reactions is the influence of transport phenomena. The reaction partner hydrogen must be transported to the catalyst, and thereby it should penetrate the gas-liquid inter-... 

The result of the described methodical solution to monitor gas-consuming reactions at reduced partial pressure under isobaric conditions is shown in Figure 10.8 for the catalytic hydrogenation of COD with a cationic Rh-complex. The slope of the measured straight lines corresponds to the maximally obtainable rate (Vsat = k2 [E]0 = k 2 [H2] [E]0) [42 b], which is directly proportional to the hydrogen concentration in solution and at validity of Henry s law to the hydrogen partial pressure above the reaction solution. The experiments prove that the dilution factor of the gas phase can adequately be found in the rate constant (Further examples can be found in [47].)... 

Fig. 10.9 (a) Schematic arrangement for the NMR-spectro-scopic monitoring of gas-consuming reactions under catalytic conditions according to [50]. (b) Gas flow during the measurement (a - argon, b - hydrogen). 

Case 1 in Figure 45.2 refers to a case where the reaction between S and H2 is very slow. In that case, the rate of hydrogen consumed by the reaction (i.e., the rate of the reaction) is small compared to the maximum rate of mass transfer. Thus, mass transfer feeds the liquid phase easily with dissolved hydrogen. The liquid-phase hydrogen concentration is very close to that at equilibrium given by the Henry s law ... 

The numerator contains all hydroxyl radical forming reactions and all initiating reactions are summarized (Sk c(/()). The denominator contains all hydroxyl radical consuming reactions. The second term includes all reactions with intermediates (EkPi c(P,)), the third the reactions with scavengers(Lksi c(S,)). Similarly, the steady-state concentrations of ozone and hydrogen peroxide can be calculated from the liquid phase mass balances. 

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