Effect of Pore Structure in Mesoporous Silicas on VOC Dynamic Adsorption/Desorption Performance

Abstract

The dynamic adsorption/desorption behavior of volatile organic compounds (VOCs) such as toluene (C7H8) and benzene (C6H6) was evaluated for three kinds of mesoporous silicas of SBA-15, all having almost the same mesopore size of ca. 5.7 nm, and a MCM-41 silica with a smaller pore size of 2.1 nm using a continuous three-step test. The fiberlike SBA-15 silica exhibited exceptionally good breakthrough behavior, a higher VOC capacity, and easier desorption. The fiberlike silica was composed through the catenation of rodlike particles. The rodlike silicas, by comparison, were proven to be less useful in dynamic adsorption processes because of lower dynamic VOC capacities despite having comparative porous parameters with the fiberlike silica. The large dynamic VOC capacity of the fiberlike silica was attributed to the presence of a bimodal pore system consisting of longer, one-dimensional mesopore channels connected by complementary micropores.

Adsorption and desorption performance of benzene over hierarchically structured carbon–silica aerogel composites

“…It is obvious that AC represents the longest breakthrough time of benzene. However, the post-breakthrough curves of AC for benzene adsorption increase more gradually with time compared with the other two samples, implying significantly large mass transfer resistance in AC [26]. The dynamic adsorption capacity of benzene increases in the order of AC > CSA-2 > CSA-0 (Table 3), corresponding to the micropore volume of the adsorbents, which is consistent with the literature [26].…”

“…As shown in Table 2, the equilibrium adsorption capacity of benzene for CSA-2 (5.06 mmol g −1 ) is higher than that for microporous AC (4.37 mmol g −1 ) at relatively high temperature of 45 • C, and the equilibrium adsorption capacity changes in the order of CSA-2 > CSA-0 > AC. This result can be explained by the fact that the static VOC adsorption capacity is proportional to the total pore volume, in accordance with the literature [26]. The Henry constants, which reflect adsorption affinity in the line region of the adsorption isotherm, can be estimated from the adsorption date at very low pressure (P < 3 mbar), where the interaction between adsorbed molecules may be neglected and only interactions between adsorbed molecules and the surface remain [27].…”

“…A breakthrough measurement is a direct method designed to explore the dynamic performance of VOC adsorption at low concentrations [26]. The breakthrough curves of benzene adsorption under dry and wet conditions and the corresponding purge curves with nitrogen on CSA-0, CSA-2 and AC samples are shown in Fig.…”

Study of the Influence of Pore Width on the Disposal of Benzene Employing Tunable OMCs

“…Previous studies associated with the adsorption properties of VOCs on carbon materials pointed out that, in the case of physical adsorption, the adsorption amount of adsorbate is determined only by the total pore volume and not the pore size distribution. 32 However, this result is inconsistent with the previous result that, under physical adsorption conditions, the pore size of the adsorbent has a significant influence on the adsorption amounts of adsorbates.…”

Effect of MnO2 Crystalline Structure on the Catalytic Oxidation of Formaldehyde

“…High specific surface materials, such as activated carbon and molecular sieve are common used in adsorption technology to remove formaldehyde (Kosuge et al, 2007;Ma et al, 2011;Chen et al, 2014), but the difficulty of regeneration on absorbent have restricted the applicant in high concentration of HCHO. At room temperature, HCHO can be decomposed through the activity of hydroxyl radicals and superoxide radicals by using TiO 2 nanoparticles as photocatalyst.…”