Desorption of benzene

Benzene chemisorption on platinum-alumina in the range 26°-470°C has been measured in a flow system by Pitkethly and Goble (7). A small dose of benzene was injected into a stream of inert carrier gas and transported to the reactor the effluent was then sampled repeatedly and analyzed by gas-liquid chromatography. Information concerning the adsorption and desorption of benzene was obtained from the shape of the subsequent benzene concentration versus time curves. Evidence was obtained for four types of adsorption of benzene ... 

Fig. 4 (a) Stepwise dehydrocyclization of -hexane (21, 62). (b) Temperature programmed desorption of benzene originating from various adsorbates over Pt-AljOs. Temperature of adsorption 25°C. Rate of heating 23°C per minute. Detector monopolar mass spectrometer, the ordinate corresponds to the I intensity of mass number 78, in arbitrary units. For clarity, the thermodesorption curves for other compounds (starting hydrocarbon) hexene from hexa-dienes and hydrogen have not been shown (62c). 

Rogers, R.D., McFarlane, J.C., and Cross, A.J. Adsorption and desorption of benzene in two soils and montmorillonite clay. 

The FTIR-TPD profiles (A vs. T) for the desorption of benzene, toluene, and ethylbenzene from high-silica H-ZSM-5 is reported in Figure 4.40 [97], These results were fitted with the complementary error function, that is,... 

The first application of hierarchical SA for parameter estimation included refinement of the pre-exponentials in a surface kinetics mechanism of CO oxidation on Pt (a lattice KMC model with parameters) (Raimondeau et al., 2003). A second example entailed parameter estimation of a dual site 3D lattice KMC model for the benzene/faujasite zeolite system where benzene-benzene interactions, equilibrium constants for adsorption/desorption of benzene on different types of sites, and diffusion parameters of benzene (a total of 15 parameters) were determined (Snyder and Vlachos, 2004). While this approach appears promising, the development of accurate but inexpensive surfaces (reduced models) deserves further attention to fully understand its success and limitation. 

To be able to express Cp.s solely in terms of the partial pressures of the species present, we must evaluate Cg-s- The rate of desorption of benzene is... 

Before checking to see if Figure 10-12 is consistent with experimental observation, we shall derive the corresponding rate laws and initial rate plots when the surface reaction is rate-limiting and then when the desorption of benzene is rate-limiting. 

At first, characteristics of activated carbons basing on porous structure and specific surface, content of ash, water adsorption and mar resistance has been determined. The volume of pores (radius of capillaries from below 1.5 to 10 nm) and the specific surface of carbons have been determined by means of dynamic adsorption and desorption of benzene vapour on the sorptive porometer DHL-3 [30]. Pores of greater radius have been determined by means of method of mercury forcing (under pressure) in carbon sample on the porometer of Carlo Erba [31 ]. 

Ramirez-Cuesta A, Valladares D, Velasco A, Zgrablich G, Tysoe WT, Ormerod RM, Lambert RM (1993) Desorption of benzene from Pd(lll) A simulation study. J Phys Condens Matter 5 A137... 

Figure 16 Desorption of benzene (w/e = 78) following 70 Langmuir acetylene at 150 K for various Pd coverages as indicated. (From Ref. 100.)...

Typical units of fco db s and kPa, respectively. By viewing the desorption of benzene. 

Is the Surface Reaction Rate-Limiting 677 Is the Desorption of Benzene Rate-Limiting 678... 

J. R. Katzer We are using a similar explanation for our results on the desorption of benzene and cumene from H-mordenite and have reported this work at the Puerto Rico A.I.Ch.E. meeting in May, 1970. (Ind. Eng. Chem. Fundamentals, in press.) I think that this is an important factor. If you could do some desorption measurements, the results would be very helpful and would clarify your speculation. We showed quite clearly that benzene and cumene molecules cannot counterdiffuse in the H-mordenite pores at reasonable temperatures. 

The rate constants for bond breakage and bond formation, fcs and ki, are each assumed to be much smaller than, the rate constant for benzene desorption. Since fcs is much smaller than fcs, the rate constant for cumene desorption (4), it is reasonable to expect that fcs is also much less than fco, the rate constant for the desorption of benzene, a weak adsorbent. In addition, we know from scheme (I) that... 

In Tables 2-4 the corrected diffasion coefficients, determined by the single-stq) method using both Equations 7 and 10 or 11 and the fall FR method are listed. These values agree within a factor of 2, even for the fast diffasion of benzene in NaX by the two methods suggesting that the rate curve in Figure 4 is a reasonably accurate representation of the rate of sorption/desorption of benzene in NaX. Although the rise/fall time of the pressure step is comparable to the time taken to sorb/desorb die small increment of sorbate and the pressure is,... 

Different types of experiments were performed with n-hexane and benzene. Here we report the results concerning, first, their competitive adsorption, then the desorption of benzene... 

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