Desorption toluene

The abihty of a four-parameter, two-parallel reaction model to correlate pilot-scale rotary kiln, toluene-desorption results (26) is shown in Figure 6. The model assumes that the adsorbed toluene consists of two fractions, T and F, which are tightly and loosely bound, respectively. 

Toluene in air Lab method using pumped charcoal adsorption tubes, solvent desorption and gas chromatography 36... 

Butadiene m air (molecular sieve diffusive samplers, thermal desoiption and gas chromatography) Toluene in air (charcoal diffusive samplers, solvent desorption and gas chromatography)... 

It is evident from these results that the interactive properties of the investigated SEC PS/DVB or DVB gels are very different. Because polar electroneutral macromolecules of PMMA were more retained from a nonpolar solvent (toluene) than from polar ones (THF, chloroform), we conclude that the dipol-dipol interactions were operative. Columns No. 1 and No. 2 were very interactive and can be applied successfully to LC techniques that combine exclusion and interaction (adsorption) mechanisms. These emerging techniques are LC at the critical adsorption point (18), the already mentioned LC under limiting conditions of adsorption (15,18), and LC under limiting conditions of desorption (16). In these cases, the adsorptivity of the SEC columns may even be advantageous. In most conventional SEC applications, however, the interactive properties of columns may cause important problems. In any case, interactive properties of SEC columns should be considered when applying the universal calibration, especially for medium polar and polar polymers. It is therefore advisable to check the elution properties of SEC columns before use with the... 

The form of experimental dependences shown in Fig. 6 indicates that slow steps are arranged consecutively in the coupled system and that desorption of the intermediate product, toluene, is fast compared with its further transformation to benzene. Otherwise, the concentrations of these two compounds (at least at the beginning of the reaction) would have shown a parallel increase [compare with (16) and with Fig. 5]. Similarly,... 

The reason for enhancement of adsorption performance of PA/AC was considered to be due to combination effect of increase of BET surface area and chemical modification by the treatment with PA. Consequently, lwt%-PA/AC was determined to be a best candidate as an adsorbent for removing benzene, toluene, p-xylene, methanol, ethanol, and iso-propanol. Therefore, lwt%-PA/AC was used as the adsorbent to investigate the adsorption isotherm, adsorption and desorption performance. 

Fig. 4 shows the TPD experimental results for lwt%-PA/AC with toluene and MEK. The desorption characteristics of lwt%-PA/AC with toluene and MEK were determined by raising the room temperature by 5°C /min to 300 0. Maximal desorption concentrations and temperatures of both toluene and MEK were 1.13,1.25 and 15010, loot, respectively. The toluene and MEK adsorbed on lwt%-PA/AC was completely desorbed when the adsorbent was heated in an electric furnace. The temperature of the adsorbent was programmed, and concentration of VOCs desorbed could be controlled at some extents. The desorbed efficiencies of toluene and MEK were 98.1% and 99.1%, respectively. Similar TPD... 

A high coverage of toluene implies that the right-hand term in the denominator is substantially larger than unity. In this case the order of reaction in methylcydo-hexane becomes zero. In practice, we could say that the reaction is limited by the desorption of toluene from the surface. 

Derive an expression for the rate of toluene formation, assuming that the reactions occur in the forward direction only and that the surface coverage of toluene is much larger than that of methylcyclohexane, while desorption of toluene determines the overall rate. 

Toluene alkylation with isopropyl alcohol was chosen as the test reaction as we can follow in a detail the effect of zeolite structural parameters on the toluene conversion, selectivity to cymenes, selectivity to para-cymene, and isopropyl/n-propyl ratio. It should be stressed that toluene/isopropyl alcohol molar ratio used in the feed was 9.6, which indicates the theoretical toluene conversion around 10.4 %. As you can see from Fig. 2 conversion of toluene over SSZ-33 after 15 min of T-O-S is 21 %, which is almost two times higher than the theoretical toluene conversion for alkylation reaction. The value of toluene conversion over SSZ-33 is influenced by a high rate of toluene disproportionation. About 50 % of toluene converted is transformed into benzene and xylenes. Toluene conversion over zeolites Beta and SSZ-35 is around 12 %, which is due to a much smaller contribution of toluene disproportionation to the overall toluene conversion. A slight increase in toluene conversion over ZSM-5 zeolite is connected with the fact that desorption and transport of products in toluene alkylation with isopropyl alcohol is the rate controlling step of this reaction [9]... 

Besides methane and hydrogen, other products observed were mainly ethane, ethylene (probably due to propane cracking), propene which are shown in figure 3. Minor amounts of benzene and toluene were also found but these products could not be quantified because their slow desorption from the zeolite s channels. 

We then designed model studies by adsorbing cinchonidine from CCU solution onto a polycrystalline platinum disk, and then rinsing the platinum surface with a solvent. The fate of the adsorbed cinchonidine was monitored by reflection-absorption infrared spectroscopy (RAIRS) that probes the adsorbed cinchonidine on the surface. By trying 54 different solvents, we are able to identify two broad trends (Figure 17) [66]. For the first trend, the cinchonidine initially adsorbed at the CCR-Pt interface is not easily removed by the second solvent such as cyclohexane, n-pentane, n-hexane, carbon tetrachloride, carbon disulfide, toluene, benzene, ethyl ether, chlorobenzene, and formamide. For the second trend, the initially established adsorption-desorption equilibrium at the CCR-Pt interface is obviously perturbed by flushing the system with another solvent such as dichloromethane, ethyl acetate, methanol, ethanol, and acetic acid. These trends can already explain the above-mentioned observations made by catalysis researchers, in the sense that the perturbation of initially established adsorption-desorption equilibrium is related to the nature of the solvent. 

A toluene solution of polymer 15 was added to an aqueous mixture of peptides. After effective equUibration, the heterogeneous mixture was allowed to separate and the organic layer was analyzed by matrix assisted laser desorption ionization mass spectrometry analysis. Because the pH of the aqueous solution was 7.1, the peptides with pis above 7.1 were extracted and the peptides with pis below 7.1... 

A third problem is related to the slow baek-desorption of the produets of reaetion, when they form on metal-oxide nanopartieles within a host ordered porous siliea matrix. For example, in toluene oxidation to benzaldehyde over Fe-Mo-oxide nanopartieles stabilized within a siliealite matrix, the slow rate of reoxidation of the redueed Fe-Mo-oxide, due to the low nanopartiele size, inereases the presenee of redueed molybdenum sites, whieh, interaeting with the earbonyl group of benzaldehyde, slow down the desorption and enhanee the rate of the eonseeutive oxidation. " ... 

ESTD, ex situ thermal desorption VOCs, volatile organic compounds TPH, total petroleum hydrocarbons BTEX, benzene, toluene, ethylbenzene, xylene PCBs, polychlorinated biphenyls PAHs, polycyclic aromatic hydrocarbons ISTD, in situ thermal desorption. 

We attempted to standardize on Chromosorb 102 for collection and on desorption of the sample with toluene for all pesticides amenable to analysis by gas chromatography. In a few cases, Chromosorb 102 was not acceptable, usually because of reduced recoveries in these cases, XAD-2 was used. The reason for reduced recoveries was not apparent. The difference in behavior between Chromosorb 102 (Johns-Manville Corp.) and XAD-2 (Rohm and Haas) remains to be... 

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