Adsorption and Diffusion Properties of Toluene on Y Zeolites by Steam–Acid Treatment: Effects of Mesoporosity and Surface Acidity

Abstract

Owing to the great importance of zeolite Y in industrial catalysis, the adsorption equilibrium and diffusion of toluene on a series of steaming and acid leaching Y zeolites were investigated to obtain an insight into the effects of secondary mesoporosity and surface acidity in the Y zeolites on the adsorption and diffusion properties. The adsorption isotherms of toluene on the treated Y zeolites can be fitted favorably by the dual-site Toth model relative to the single-site Toth model of the initial micropore Y zeolite. The temperature-dependent parameters including maximum adsorbed amount q s, affinity constant b, isosteric heat of adsorption Q, Henry’s constant K H, and initial heat of adsorption Q st were discussed in terms of the microporosity, mesoporosity, and acidic site density, revealing the enhancement of the adsorbed amount and the weakening of the toluene–zeolite interaction of the Y zeolite after steam–acid treatment. The diffusion of toluene on the Y zeolite was examined by means of desorption curves from the zero-length column chromatography technique. The correlation of the effective diffusion time constant D eff/R 2 and the activation energy E a with meso-/microporosity and acidic site density reveals that the diffusion is improved with the decreasing strength of the interaction between toluene and zeolite and the increasing meso-/microporosity in the Y zeolite.

β Zeolite Nanostructures with a High SiO2/Al2O3 Ratio for the Adsorption of Volatile Organic Compounds

“…Notably, Nano-β zeolites demonstrate the adsorption capacity of the order of Nano-B 600 > Nano-B 400 > Nano-B 200 > Nano-B 100 , and Nano-B 600 possesses adsorption capacity (38.1/100 g) much higher than that of Nano-B 100 (27.8/100 g). The specific surface area and mesoporous pore volume and total pore volume of high-silica β zeolite are much higher, which demonstrates that the porosity of the adsorbent is the main factor affecting the adsorption capacity. , In addition, the surface of β zeolite has a positive active site, which is related to SAR, which can interact with π electron of toluene and improve the adsorption capacity . Moreover, the adsorption of VOCs in a moist environment is shown in Figure a.…”

“…The specific surface area and mesoporous pore volume and total pore volume of highsilica β zeolite are much higher, which demonstrates that the porosity of the adsorbent is the main factor affecting the adsorption capacity. 56,57 In addition, the surface of β zeolite has a positive active site, which is related to SAR, which can interact with π electron of toluene and improve the adsorption capacity. 29 Moreover, the adsorption of VOCs in a moist environment is shown in Figure 7a.…”