Analysis of Toluene Adsorption on Na-Form Zeolite with a Temperature-Programmed Desorption Method

Abstract

Temperature-programmed desorption (TPD) of toluene was carried out on various zeolites, and theoretically analyzed to determine thermodynamic parameters. The TPD process was identified as the case of equilibrium control, showing that the analytical method, the same as that for ammonia TPD, can be applied to the toluene TPD to calculate the adsorption heat. It was observed that approximately one toluene molecule was adsorbed on one Na + cation for MFI and BEA. The heat of toluene adsorption on Na + was MOR > MFI > BEA > FAU, similar to the heat of ammonia adsorption on the corresponding H-form zeolite. A linear relationship was observed between both adsorption heats. It suggests that the adsorption of toluene on Na + is controlled by the electron-withdrawing nature of the ion exchange site, as well as the Brønsted acid strength of the H-form zeolite.

Synthesis and Toluene Adsorption/Desorption Property of Beta Zeolite Coated on Cordierite Honeycomb by an In Situ Crystallization Method

“…6. HBeta showed a dominant and symmetric peak at lower temperature (with maxima at 141°C), similar to the result in [26]. In contrast, two significant differences in the desorption profile of HBeta/Cd were observed: (i) the desorption stage at lower temperature is asymmetric; (ii) the desorption stage at higher temperature is evident.…”

“…No significant mass number peak was observed except the mass numbers exclusive to toluene (39, 45, 46, 50, 51, 61, 62, 63, 65, 89, 91, 92, and 93). This suggested that toluene was reversibly adsorbed and desorbed on the bulk sample without considerable side reaction [26]. On the other hand, the MS signal of 91 over HBeta/Cd (see Fig.…”

Non-Calorimetric Determination of the Adsorption Heat of Volatile Organic Compounds under Dynamic Conditions

“…In the present work, it has been found that about 12% and 6% of o-xylene, on bentonite and silica, respectively, remained adsorbed although the isothermal desorption curve reached zero. This adsorptive behavior suggests the use of the Temperature-Programmed Desorption (TPD) method for determination of desorption energy Ed value, as firstly reported by Cvetanovic, then by several authors [1,9,[40][41][42]. The method is based on measuring the desorption profile with temperature increase, which goes through a maximum and finally back to zero, indicating that the surface is cleared of adsorbate.…”

Hydrocarbon Reformer Trap by Use of Transition Metal Oxide-Incorporated Beta Zeolites

“…Therefore, acidity is quite important to trap and hold HCs until high temperatures are reached under our experimental conditions. Niwa's group has recently reported that Na + plays a quite interesting role in holding HC due to the electrostatic interaction with aromatic pi electrons [19]. High silica zeolites are applied in such an adsorbent owing to their hydrophobic interaction and micropore filling.…”