Hydrogen isotherms

Fig. 2. Type I hydrogen isotherms O, hydrogen activation A, oxygen activation (solid symbols denote desorption points). 

Hydrogen isotherms at 77 K and up to 4 MPa were carried out in a DMT high-pressure microbalance. The sample was degassed at 423 K during 4 hours under vacuum. Sample weight was between 250 to 750 mg. The experimental results were corrected for buoyancy effects related to the displacement of gas by the sample, sample holder and pan21. 

Values for the irreversible chemisorption of CO on Pt/Si02 and PtSn-BM are included in Table 6.3. The tendency is similar to that of hydrogen isotherms. The CO/Pt value changes from 0.56 to 0.25 when the monometallic catalyst is modified by hn addition at an atomic ratio of Sn/Pt = 0.71. 

With the purpose of a choice of the most suitable sorbent of hydrogen, isotherms (Fig. 7) of studied materials were compared at a level of pressure 3.5-6 MPa, representing practical interest for development of onboard storage system. It is obvious, that the best sorbent in the field of nitrogen temperature - the activated fiber "Busofit-M8", having major effective porosity (0.78), bulk density of 500 kg/m3 and an advanced surface area (2985 m2/g). 

Another typical hydrogen isotherm on Pt/Al203 [published by Ostermaier et al. 21)] exhibited such a plateau, the gradient of which was not zero. With their conditions [P(H2) = 760 Torr, T = 25°C], they found a H/Pts ratio as high as 5.6. They reported a very slow uptake of hydrogen for all their experiments, which agrees with the other studies of sorption rates. 

Method 1 Cool from 400X to RT in hydrogen isotherm measured at RT. h Method 2 Isotherm measured at 100°C. 

Citral was hydrogenated isothermally in ethanolic solutions at 60-77 °C, in a semibatch reactor working at atmospheric pressure. Hy ogen was dispersed into the reaction mixture through separate glass sinters. A reflux condenser was placed on top of the reactor in order... 

The hydrogenation isotherms measured by Vajo et al. (2005) clearly show that destabilisation occurs. Measuring these isotherms was hampered by slow kinetics, resulting in sloping plateaus and some incomplete isotherm curves. However, if this were not a concerted reaction one would expect to... 

Uhr] Microprobe measurement, optical microscopy, XRD, equilibration of alloys with hydrogen Isothermal section at 1000°C, 0.5 to 40 mass% Mo at ac = 0.03 to 1... 

Fig. 6.11. Hydrogen isotherm on nickel-kieselguhr catalyst obtained from deuterium chromatography. Note Data points of 0 C and—20 C not shown. (Reproduced with permission by Suzuki, M. and Smith, M., J. Catai, 23, 325 (1971)).

FIGURE 6.15 Hydrogen isotherms on Pt-doped IRMOF-8 samples with different Pt catalyst sizes (Ref. [149]). 

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