Adsorption of propane

Figure 11.16. Langmuir plots for the adsorption of propane by 5A zeolite (reproduced courtesy of Ruthven and Loughlin, 1972).

Figure 1 shows the rate of adsorption of N2 on 4A powder and concurrent temperature measurements. Figure 2 gives the rate of adsorption of propane on 5A with a thin (0.3-mm) and a thick (4-mm) layer of zeolite on the balance pan temperatures were measured in a separate experiment in the thick layer. 

Ordinary drying of the gel at room temperature or at 100° followed by heating to 200-400° in an inert atmosphere leads to the formation of a black material which is amorphous to X-rays and which has a surface area in the vicinity of 300 m /gm. The surface area is almost entirely in micropores about 10 A in width 27, 28). The adsorption of propane at — 78° fits a Langmuir adsorption isotherm with great accuracy 27). 

Equation (2) explains the transient deactivation with a model describing reversible and irreversible coke. We can see that the partial pressure of propane in the reactor does not influence the deactivation. This has also been demonstrated in an earlier study of the same system [8]. This observation is consistent with kinetic models for propane dehydrogenation proposed by Loc et al. [13]. They suggested that the rate-determining step is the dissociative adsorption of propane. From this mechanism it follows that the deactivation will be... 

FIGURE 6.20. Test of the spinning basket adsorber. Overall rate coefficients for adsorption of propane on Linde 5A at 54 C were measured at several speeds of rotation in the presence of 500 Torr of either iQH,) or SFj. These species are both too large to penetrate the sieve. The uptake rate correlates with the gas phase molecular diffusivity indicating external mass transfer control. (Data of Taylor.< °>)... 

The adsorption of propane onto platinum from concentrated phosphoric acid using anodic galvanostatic charging and cathodic hydrogen deposition has been reported. A typical result is given in Figure 12. It was concluded that, at least initially, propane requires three sites for adsorption and that equilibrium adsorption is obtained after about 1 min, with a maximum coverage between 0.3-0.5. 

Rimpel, A.E. Camp, D.T. Kostecki, J.A., and Canjar, L.N., Kinetics of physical adsorption of propane from helium on fixed beds of activated alumina, AlChE J., 14(1), 19-24 (1968). 

A plot of p 10 against p will yield a straight line with intercept l/K when the Langmuir model applies. Eigure 27.4(a) shows that the Langmuir model predicts the adsorption of propane in zeolite pores. 

An example of this relation is given in Fig. 4.8 for gaseous phase adsorption of propane and butane on activated carbon pellets. A are well plotted in proportion to 9 d Inp/d In 9 determined from the isotherm relations. 

Acidic or basic promoters can affect the activity of Pt and Pd supported on alumina or zirconia. Basic promoters (e.g. Na) improve CO and propene oxidation while they inhibit NO oxidation. By contrast, acidic promoters (e.g. sulfates) show the greatest effect in propane oxidahon. Carbon monoxide and propene are too shongly adsorbed (with respect to O2) the effect of basic promoters would be to weaken their adsorphon on the metals and thereby to reinforce that of oxygen. The reverse is true for acidic promoters they strengthen the adsorption of propane, too weakly adsorbed on Pt and Pd (see Section 1.2.5). The same result can be observed if sulfates are replaced by SO2 directly injected with the propane/air mixture. The... 

The goal of this work was the study of the effect the surface chemistry of a carbon molecular sieve (Takeda 5A) in the adsorption of propane and propylene. The CMS was oxidized by two different agents, and thermal treatments imder vacuum and different... 

A Tian-Calvet microcalorimeter (model BT 2.15, Setaram, France) was used to measure the enthalpies of adsorption of propane and propylene at room temperature. The samples (0.1 g) were treated under different conditions (i) vacuum at 523 K, (ii) vacuum at 773 K, (iii) He at 1073 K and (iv) H2 at 1073 K, all for 4h. Then, thqr were s ed into a Pyrex RMN tube in pure He and placed into the microcalorimetric celL A conventional manometric system coupled to the microcalorimet was used to m isare the amount adsorbed employing a (type 660) manometer witii a pr xsion of 0.001 Torr. The maximum apparent leak rate of the manometric system (including tire calorimetric cells) was 10 Torrmiri in a volume of about 60 cm. ... 

The increase in weight of CaA adsorbents during the adsorption of propane and pentane was monitored at 373 and 523K., Fig. 1. 

At 523K, the adsorption of propane is less than 1%, while the pentane is considerably adsorbed and the order of adsorption is preserved versus calcium exchange. In this case, a... 

Figure 3.4 The adsorption of propane on a 5i4 zeolite apparently obeys a Langmuir isotherm (source Ruthven and Loughlin 1972).

Larsson et al. (1998) performed DHP kinetic experiments on a Pt-Sn/ Y-AI2O3 catalyst (0.54 wt% Pt and 1.53 wt% Sn) under these experimental conditions temperature 507-547 °C, total pressure 1.5 bar, and flow rate 60ml/min (propane 18.1—27.2 ml/min, propylene 2.7—4.5 ml/min, and H2 4.1-6.7 ml/min). A power-law model (see Table 2.4), and two categories of L-H models with dissociative adsorption of propane and propylene desorption as the rate-determining step (RDS) respectively were proposed. But the authors had difficulties in obtaining some important parameters mainly due to the fact that the experiments were conducted in a relatively limited range of operating condition. Finally, they adopted a power-law equation for the kinetic model. 

A kinetic model of DHP over a commercial Pt-Sn/Al203 catalyst was obtained by Faijoo et al. (2011). The temperature used in this study was 580-620 °C and a iaxed H2/C3Hg molar ratio of 0.8 was used. Four L-IT models were developed by assuming dissociative adsorption of propane or propyl dehydrogenation as the RDS. The L-Fl model (see Table 2.4) with the dissociative adsorption of propane as RDS provided the best agreement with experimental data. 

Assuming the dissociative adsorption of propane (2.5) as the RDS, the rate expression was derived as ... 

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