Hydrogen consumption rate

The reaction rate was calculated from hydrogen consumption, from pressure drop. As the hydrogen consumption rate was dependent on amount and purity of substrate, catalyst weight and metal content, conversion rate was given (%/min mg Pd), the measured total hydrogen consumption was taken equivalent with 100% conversion. 

Small-scale reforming systems are relatively complex because they need fuel and air-feed systems, the reformer, a hydrogen purification system, and various cooling and water processing ancillary systems to make it all work. The systems also have to employ a specific hydrocarbon that is available at a reasonable cost at a customer s location. These systems probably work best for customers with hydrogen consumption rates in the 1500 scf/hr to 10,000 scf/hr range. They... 

The influence of the amount of zinc salt added on the hydrogen consumption rate and on the initial selectivity to cycloalkenes in the hydrogenation of benzene is illustrated by Struijk... 

Figure 20. Time courses of hydrogen consumption rate and catalyst potential during hydrogenation on suspended catalyst at 298 K (Beck ° ). (lA, B) Hydrogenation of dimethylethinyl carbinol on Pd (4.5%)/Si02 catalyst (5 g). 0,5 M in triethanolamine-buffered methanol solution (pH 8), 500 cm (2A, B) Hydrogenation of 2-butyne-l,4 diol on Pd (5%)/Al203 catalyst (5 g). 0.06 M solution in triethanolamine buffered aqueous solution (pH 8), 500 cm. ...

The current generated by the fuel cell stack is directly proportional to the hydrogen consumption rate. The voltage generated by a cell depends on the current density in the cell, thermodynamic... 

Figure 9.30. Steady-state effect of catalyst potential, Urhe, on the rate enhancement ratios, Ph2 = fH2 / r 2 and po = ro /Iq and on the corresponding consumption rates of hydrogen and oxygen. Conditions as in Fig. 9.26.35 Reproduced by permission of The Electrochemical Society.

Transient computations of methane, ethane, and propane gas-jet diffusion flames in Ig and Oy have been performed using the numerical code developed by Katta [30,46], with a detailed reaction mechanism [47,48] (33 species and 112 elementary steps) for these fuels and a simple radiation heat-loss model [49], for the high fuel-flow condition. The results for methane and ethane can be obtained from earlier studies [44,45]. For propane. Figure 8.1.5 shows the calculated flame structure in Ig and Og. The variables on the right half include, velocity vectors (v), isotherms (T), total heat-release rate ( j), and the local equivalence ratio (( locai) while on the left half the total molar flux vectors of atomic hydrogen (M ), oxygen mole fraction oxygen consumption rate... 

H2TPR results (Flow rate of 5% H2 = 20cc/min, Ramp rate= lOtl/min) show that Sb modifies the catalyst surface reducibility. The hydrogen consumption on WO3 takes place above 500 °C. It is evident from TPR results that new surface species were formed by Sb addition. The population of such species, that is represented as the area under the new peak, increases with increasing Sb content with the maximum at Sb=0.4 and then decreases with further increasing Sb content. 

ADN, 19.4% CL, 1.3% ACAM, 2.2% CVAM and 30.9% others and was hydrogenated with Raney Co 2724 under identical conditions to the above. The reaction showed an initial hydrogen uptake rate of 7.8 psi (53.8 kPa)/minute. After 240 minutes, the reaction had consumed 525 psig (3.72 MPa) a sample was removed from the reactor for analysis. It comprised 39% HMD, 18% CL, and by-products. The reaction showed no evidence of catalyst deactivation. While the rate of hydrogen consumption was detectably larger in this experiment than in the Raney Co experiment with C02 and NH3, the differences are not sufficiently large to infer a mechanistic difference. 

The common further treatment of the approach - assumption of steady-state conditions for the intermediate substrate complexes, consideration of the catalyst balance ([catalyst]0=[solvent complex] + [IRe] + [Isi] + [IIRe] + [Hsi]) and of the stoichiometry of the hydrogenation - provides the rate of hydrogen consumption under isobaric conditions (Eq. (13)) [57f]. A more general derivation can be found in [59]. 

Clearly, a comprehensive description of catalytic systems is not possible from the hydrogen consumption alone. The reaction sequence represented in Scheme 10.3 already contains 16 rate constants. However, valuable data regarding the catalysis can be obtained from an analysis of the gross hydrogen consumption on the basis of Eq. (13), for various catalytic systems. Some practical examples of this are described in the following section. 

The comparison of hydrogen consumption in the rhodium-catalyzed enantiomeric hydrogenation of a yS-dehydroamino acid using Et-Duphos (Et-Du-PHOS = l,2-bis(2,5-diethyl-phospholanyl)benzene)) as the chiral ligand shows the huge differences in rate, depending on the manner in which the catalyst was prepared (Fig. 44.1) [10b,c]. 

Note that the ratio robs = 0H/VR (mol s 1 m 3) is the observed rate of hydrogen consumption from the gas phase. 

Typically, hydrogen sulfide does not occur in wastewaters from gravity sewers if the DO concentration is higher than 0.2-0.5 g m-3 (USEPA, 1974). If the DO concentration becomes lower, either because of a high DO consumption rate or because of reduced reaeration, Equation (3) in Table 6.1 has been proposed for the prediction of sulfide (USEPA, 1974). However, even where... 

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