Methane loading

The same study has been performed concerning the methane / ZSM-12 zeolite system. The neutron diffractograms, measured for different methane loadings of ZSM-12 zeolite, are represented on figure 9. In addition, a methane calibration sorption isotherm... 

The calculated diffusion coefficient is in remarkably good agreement with a value found from NMR measurements at the same temperature and methane loading the simulations predicted a value of 0.66 X 10 8 m2/s, and the experiments gave (0.65 0.1) x 10 8 m2/s (76). The uncertainty of the theoretical result is difficult to gauge. When the framework is fixed,... 

Zibrowius et al. (77) used an NMR spin-echo attenuation technique to estimate the ratio of the diffusion tensor element related to motion along the y-axis (the straight channel) and the average of the other two elements. For a methane loading of 8 molecules per unit cell, the ratio was estimated to be less than 5 at room temperature ... 

Figure 6.30. Gibbs excess mass of (CH4, 5.5) sorbed in polycarbonate (GoodfeUow, UK) at T = 308 K for gas pressures up to 4 MPa and static dielectric permittivity (e,) of the (methane loaded) polymer [5.2,6.3].

An anaerobic digester is a no-recycle complete mix reactor. Thus, its performance is independent of organic loading but is controlled by hydraulic retention time (HRT). Based on kinetic theoiy and values of the pseudo constants for methane bac teria, a minimum HRT of 3 to 4 days is required. To provide a safety factor and compensate for load variation as indicated earlier, HRT is kept in the range 10 to 30 days. Thickening of feed sludge is used to reduce the tank volume required... 

GrenzflSjchen-erscheinung, /. interfacial phenomenon, -katalyse, /, contact catalysis, -spannung, /. interfacial tension. Grenz-gesetz, n. limit law (one which natural phenomena approximate but never actually fulfill), -kohlenwasserstoff, m, any hydrocarbon of the methane series, alkane, paraffin, limit hydrocarbon, -kurve,/, limiting curve, limit curve, -last, /. limit ioad, maximum load, -leistung, /, peak performance, maxi-... 

The catalysts were reduced with 100% H2 at 371 °C and an inlet space velocity of 1000/hr. Because of the carbon-forming potential of a dry gas recycle composition and the cost of reheating the recycle if the water produced by the methanation reaction is removed, a wet gas recycle composition was used. The catalyst loading, gas composition, and test conditions for these tests are listed in Table II, and the effects of nickel content are compared in Table III. 

The long term tests in the SASOL plant as well as in the Schwechat plant were run with outlet temperatures of 450°C, but both plants were also operated with higher loads that caused reactor outlet temperatures of 470°C or even higher. In comparison with the test run at 450°C, only a slight increase in deactivation rate was detectable which demonstrates the thermostability of the catalyst. From the aspect of thermostability, outlet temperatures of 450°-470°C are acceptable. Further considerations including the possibility of overload operation, the SNG specification to be achieved in final methanation, end-of-run conditions, and cost of reactor material will affect the selection of optimum outlet temperature. 

The fit of these equations to the data is very good, as seen in Fig. 18. These equations are valid to very small values of CO concentrations, where the reaction becomes first order with respect to CO. In a mixture of CO with oxygen, there should be a maximum in reaction rate when the CO concentration is at 0.2%, as shown in Fig. 19. When the oxidation of olefins and aromatics over a platinum loaded monolith is over 99% complete, the conversion of higher paraffins may be around 90% and the conversion of the intractable methane is only 10%. 

Figures. Temperature-programmed reaction of methane with FeZSM-5 surface before a-oxygen loading (a) and after ot-oxygen loading (b). A - time moment of opening the microreactor B - time moment of switching on the programmed heating (6 K/s).

Fig 3 shows the results of two temperature-programmed experiments. In the first (blank) experiment CH4 reacts with a "bare" FeZSM-5 zeolite, while in the second one it reacts with the zeolite after a-oxygen loading on its surface. Obviously, the bare surface is quite inert towards methane (Fig 3a) after reactor opening a weak CH4 adsorption occurs at room temperature. A slight heating results in a complete recovery of the CH4 pressure. 

Precious metal loaded ln/H-ZSM-5 for reduction of nitric oxide with methane in the presence of water vapor... 

The catalytic activity of ln/H-ZSM-5 for the selective reduction of nitric oxide (NO) with methane was improved by the addition of Pt and Ir which catalyzed NO oxidation, even in the presence of water vapor. It was also found that the precious metal, particularly Ir loaded in/H-ZSM-5 gave a low reaction order with respect to NO, and then showed a high catalytic activity for the reduction of NO at low concentrations, if compared with ln/H-ZSM-5. The latter effect of the precious metal is attributed to the enhancement of the chemisorption of NO and also to the increase in the amount of NO2 adsorbed on in sites. 

Figure 4 Methane (CD4) neutron diffractograms measured at T = 82 K for different loadings in AlP04-5 zeolite.

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