Microporous Silica Research Articles

Preparation of Novel Hierarchical Catalysts by Simultaneous Generation of β-Zeolite and Mesoporous Silica for Catalytic Cracking.

The gel skeletal reinforcement (GSR) method was applied at the preparation stage of β-zeolite to prepare a novel hierarchical catalyst. A solution of hexamethyldisiloxane (HMDS) and acetic anhydride, a GSR reagent, was added to the mixture of colloidal silica, sodium aluminate, tetraethylammonium hydroxide, sodium hydroxide and water, and successive aging and hydrothermal treatment gave microporous β-zeolite surrounded by mesoporous silica like core-shell structure. Its properties were characterized by XRD, nitrogen adsorption and desorption, NH3-TPD, TEM, and TG-DTA measurements, and further characteristics of the catalysts produced were clarified by the catalytic cracking of n-dodecane. The hierarchical structure of microporous zeolite and mesoporous silica was shown from GSR-2.9HS-H-Beta to GSR-3.2HS-H-Beta, where the molar ratio of HMDS and silica source of β-zeolite was 2.9~3.2 : 100. It was found that in the catalytic cracking of n-dodecane, the relative activity (the conversion per the amount of zeolite crystals) increased with the increase in mesopore volume and surface area. The result indicated that the introduction of mesopores was effective even in catalytic cracking of small molecule of n-dodecane.

Enhanced hydrogen separation performance of cobalt-doped microporous silica membranes: Influence of cobalt content and processing parameters

This research focused on synthesizing microporous silica and cobalt-doped silica through acid-catalyzed hydrolysis and condensation. The effects of various synthesis parameters (calcination temperature, cobalt content, and cobalt addition step) were investigated. The results confirmed that the presence of cobalt in the microporous structure enhances the performance of the silica membrane. However, the hydrothermal stability remained unchanged, which can be attributed to the pore size of the silica. The competitive cobalt-doped silica sol coated on a modified support, resulting in a membrane with better performance compared to the blank silica membrane. The membrane was subjected to single gas permeation tests: H2 permeance of 1.8 × 10−7 mol m−2 s−1 Pa−1 and H2/N2 selectivity of 58 at a low temperature of 200 °C. The high apparent activation energy (Ea) observed for H2, suggests the presence of a molecular sieving mechanism, which was further improved by incorporating cobalt into the microporous structure of silica.

The effect of silica nanoparticles obtained from different sources on mechanical properties of polyurethane nanocomposites

Spherical silica particles were synthesized from two different sources, tetraethyl orthosilicate (TEOS) and sodium sili-cate obtained from wheat straw ash, respectively. In the first case, monodispersed and microporous silica particles with average particle size of 400 nm were prepared by hydrolysis and condensation of TEOS. In the second case, the silica particles were generated from supersaturated sodium silicate solution. The extraction of silicate solution from wheat straw ash (WSA) was performed by the multi-step sequential extraction using 2,5 mol/L NaOH. WSA silica particles were polydispersed and contain the primary silica particles with average size of ~250 nm and agglomerates obtained by aggregation of primary silica particles, with average size of ~1.5 mm and 5 mm. The silica particles obtained from WSA have the average pore size of 28.3 nm, total pore volume of 0.1638 cm 3 /g and average surface area of 23.131 m 2 /g. Flexible polyurethane/silica composites with my(TEOS silica and WSA silica) and different filler concentration were synthesized. Dispersion of silica fillers in polyol system preceded the mixing with isocyanate resulted in formation of cavities in polyurethane-silica composite. On the other hand, dispersion of TEOS silica filler into isocyanate which preceded the mixing with polyol system resulted in homogenous and compact composite. The application of silica filler obtained from TEOS at filler concentration of 4 wt.% increased Young's modulus for 20% relative to that of polyurethane without filler. On the other side, the application of WSA silica filler resulted in reduced Young' s modulus probably due to large silica aggregates.

Electroassisted Incorporation of Ferrocene within Sol-Gel Silica Films to Enhance Electron Transfer.

The sol-gel method is a straightforward technique that allows electrode modification with silica thin films. Furthermore, the silica pores could be functionalized to enhance the electrical conductivity and reactivity of the silica films. In this context, silica thin films were functionalized with ferrocene species. This functionalization was performed by electroassisted accumulation, generating a micro-structured composite electrode (Fc@SiO2 electrode). These modified electrodes were characterized by electrochemical and spectroelectrochemical methods, pointing out that ferrocene species were confined with high stability within the microporous silica thin film, demonstrating the good adsorption capacity of the silica. While the spectroelectrochemical characterization indicates that only a fraction of the confined species within the silica films were electroactive, the electrochemical results demonstrate that the Fc@SiO2 film enhances the electrochemical response of cytochrome c in a solution, which gives rise to further applications of these films for redox-controlled release and electrochemical detection of other redox-active proteins.

Effect of the Pore Structure of Nanosilicas Decorated with Cobalt and Cerium Oxides on Catalytic Activity in the Selective Oxidation of Carbon Monoxide

Two types of nanosilicas with different pore structures are synthesized and decorated via impregnation with cobalt and cerium oxides. Meso–microporous spherical silica particles with thin walls of SiO2 nanochannels having specific surface area and pore volume of up to 1400 m2/g and 0.8 cm3/g, respectively, are used. Macroporous three-dimensionally ordered structures based on SiO2 (so-called synthetic opals) consisting of close-packed submicron spherical silica particles with respective porosity characteristics of 11 m2/g and 0.2 cm3/g are also used. The synthesized materials are characterized via low-temperature nitrogen adsorption, X-ray diffraction, SEM, XPS, and Fourier transform IR spectroscopy, and tested as catalysts for the selective oxidation of CO in excess H2 (CO-PROX). The effect of silica, the ratio of introduced oxides, and the order of their introduction on the structure and catalytic properties of Co–Ce/SiO2 are revealed. The catalytic behavior of the synthesized materials is determined from the specificity of interactions among the metal oxides and with the silica surface.

Precipitative Coating of Calcium Phosphate on Microporous Silica–Titania Hybrid Particles in Simulated Body Fluid

Titania and silica have been recognized as potential drug delivery system (DDS) carriers. For this application, controllable biocompatibility and the suppression of the initial burst are required, which can be provided by a calcium phosphate (CP) coating. However, it is difficult to control the morphology of a CP coating on the surface of carrier particles owing to the homogeneous nucleation of CP. In this study, we report the development of a CP-coating method that homogeneously corresponds to the shapes of silica–titania (SiTi) porous nanoparticles. We also demonstrate that controlled surface roughness of CP coatings could be achieved in SBF using SiTi nanoparticles with a well-defined spherical shape, a uniform size, and a tunable nanoporous structure. The precipitation of CP was performed on mono-dispersed porous SiTi nanoparticles with different Si/Ti molar ratios and pore sizes. The pore size distribution was found to significantly affect the CP coating in SBF immersion; the surfaces of the nanoparticles with bimodal pore sizes of 0.7 and 1.1–1.2 nm became rough after CP precipitation, while those with a unimodal pore size of 0.7 nm remained smooth, indicating that these two pore sizes serve as different nucleation sites that lead to different surface morphologies.

Two-step synthesis of a macroporous LTA zeolite sorbent by supercritical CO2 coating and hydrothermal conversion: Implementation in fixed-bed nuclear wastewater treatment

Fixed-bed sorption on solid substrate is a common approach to safely extract cationic radionuclides (such as 90Sr2+) from nuclear wastewater and minimize final waste volumes. This article describes the preparation and characterization of a new hierarchical zeolite–glass bead composite for this application. A homogeneous layer of microporous amorphous silica is deposited on the beads in supercritical CO2 and then transformed into a 1 µm-thick LTA (Linde Type A) zeolite film (40 wt% of the composite) by hydrothermal treatment. Microstructural data show that this design improves the accessibility of the sorbent sites for Sr2+ cations. Batch sorption data in different types of simulated wastewater quantify the effects of competing cations and high salinity. Dynamic breakthrough experiments with simulated saline wastewater show that the proposed composite has delayed leakage and faster exchange kinetics than an existing commercial LTA-zeolite sorbent, which should translate into greater waste volume reduction in industrial fixed-bed extraction systems.

Three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria as heterojunction photocatalyst to activate peroxymonosulfate for bisphenol a degradation

In this study, three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria (n-CeO2@p-LaFeO3/3DOM SiO2) was successfully synthesized as a visible light-driven photocatalyst for activating peroxymonosulfate (PMS) to degrade Bisphenol A (BPA). In a wide pH range (2–12), the BPA degradation efficiency maintained at a high level, organic matter and natural inorganic ions had no significant negative impact. When the BPA concentration was as low as 2 mg·L−1, the removal rate in 60 min still reached 95.56%, indicating that the novel photocatalyst has potential application in the treatment of trace pollutants. The pore confinement effects of catalysts and the synergistic effect between LaFeO3 and CeO2 result in the excellent photocatalytic performance. We proposed the possible mechanism of BPA degradation, specifically involving the recognition and generation mechanism of reactive oxygen species (ROSs), adsorption processes and diffusion processes. In summary, the novel n-CeO2@p-LaFeO3/3DOM SiO2 would be a promising candidate photocatalytic material for practical sewage treatment.

Drying of Hierarchically Organized Porous Silica Monoliths-Comparison of Evaporative and Supercritical Drying.

In this study, we present a detailed comparison between a conventional supercritical drying process and an evaporative drying technique for hierarchically organized porous silica gel monoliths. These gels are based on a model system synthesized by the aqueous sol-gel processing of an ethylene-glycol-modified silane, resulting in a cellular, macroporous, strut-based network comprising anisotropic, periodically arranged mesopores formed by microporous amorphous silica. The effect of the two drying procedures on the pore properties (specific surface area, pore volume, and pore widths) and on the shrinkage of the monolith is evaluated through a comprehensive characterization by using nitrogen physisorption, electron microscopy, and small-angle X-ray scattering. It can clearly be demonstrated that for the hierarchically organized porous solids, the evaporative drying procedure can compete without the need for surface modification with the commonly applied supercritical drying in terms of the material and textural properties, such as specific surface area and pore volume. The thus obtained materials deliver a high specific surface area and exhibit overall comparable or even improved pore characteristics to monoliths prepared by supercritical drying. Additionally, the pore properties can be tailored to some extent by adjusting the drying conditions, such as temperature.

Dry reforming of methane over Ni catalysts supported on micro- and mesoporous silica

Worsening global warming and the proposition of carbon neutrality brings new challenge to the utilization of carbon dioxide. Dry reforming of methane draws much attention among various utilization routes due to its high efficiency. In this work, mesoporous silica support SBA-15 and microporous silica support beta were applied to the Ni catalysts for the dry reforming of methane. Compared with the impregnated catalyst Ni/SBA-15, highly-dispersed Ni nanoparticles were obtained on Ni-SBA-15 and Ni-beta catalysts prepared by ammonia evaporation method, and they performed excellent catalytic activity, with a CO2 conversion of ca. 89 % and a CH4 conversion of ca. 84 % at 700 °C and nearly 100 % conversions at 800 °C. Benefited from the confinement of the mesopores, Ni nanoparticles were well embedded in the pores of Ni-SBA-15 and exhibited distinguished resistance to Ni sintering and carbon deposition. Ni-beta suffered relatively more intensive Ni sintering and carbon deposition because the pore size of beta was much smaller so that it was difficult to introduce Ni into its micropores by ammonia evaporation method.

On the application of adsorber plate heat exchangers in thermally driven chillers; An experimental and analytical study

The effect of both heat and mass transfer characteristic lengths (HTCL, MTCL) of two different adsorber plate heat exchangers (APHE), for application in an adsorption chiller, on the adsorption and desorption kinetics is investigated. Three representative test frames (TF1-TF3) are prepared to examine small-scale adsorbent samples of the microporous silica gel (Siogel of Oker-Chemie, Germany) applying the volumetric large-temperature-jump methodology at different operating conditions. Based on the obtained kinetic data, an analytical model has been developed to predict the specific cooling power (SCP) and the coefficient of performance (COP) of a single-bed adsorption chiller comprising the studied APHEs. It turned out that, within the tested range of HTCL and MTCL, it can be concluded that, the adsorption kinetics are mainly influenced by the MTCL, while the desorption kinetics are dominated by the HTCL of the adsorbent domain. Applying Siogel as loose pellets inside a newly introduced APHE results in SCPs of 423.3 and 182.7 W⋅kg−1, at the evaporator temperatures of 15 °C and 5 °C, respectively. Herein, the condenser and adsorber-end temperatures amount to 30 °C and the desorption-end temperature to 90 °C. The corresponding COPs amount to 0.50 and 0.40, respectively, which represent quite promising results for further design optimizations.

WO3-based porous MCM-48 catalysts for renewable acrolein synthesis by the dehydration of glycerol

The gas-phase selective dehydration of glycerol to acrolein was studied over x%W (x: 5, 15, 25, and 35 %, w/w) supported on MCM-48. Microporous silica MCM-48 was synthesized to produce three-dimensional cubic crystals with a high surface area and resistance to hydrolytic pressure. Tungsten oxide (WO3) based solid acid catalysts supported on MCM-48 were prepared by two distinct synthesis methods, namely, oxalic acid added sol–gel (HSG) and nonhydrolytic sol–gel (NHSG) methods. The morphological and textural properties of catalysts were characterized by XRD, BET, SEM, Raman, XPS, and FT-IR techniques. The acidic properties of catalysts were elucidated by FTIR pyridine-adsorption and NH3-Temperature Programmed Desorption (NH3-TPD). The total surface acid sites’ concentration, Brønsted (B) and Lewis (L) acid concentrations, and B/(B+L) ratios were calculated from NH3-TPD and pyridine-FTIR. The steady acrolein yields were obtained with the optimal catalysts (15 %W and 25 %W loaded MCM-48 for HSG and NHSG, respectively). This study demonstrated that the medium-strength surface acidity and B/(B+L) ratios for glycerol dehydration to acrolein were correlated with both the activity and the selectivity of acrolein.

Construction of novel super microporous silica adsorbents using pluronic triblock copolymer as template towards desulfurization from fuel

As an efficient fuel purification technique, adsorption desulphurization has attracted wide attention. Silicon oxide has been verified as a promising candidate for adsorption desulfurization reagent due to the advantages of stable structure, inexpensiveness and accessibility. However, its adsorption desulfurization performance is always weakened by the limited pore channel size leading to pore diffusion resistance over the traditional microporous silicon oxide, and it suffers from the poor shape selectivity of mesoporous silicon oxide as well. In this work, we successfully prepared a novel super microporous silica material (SMS) with a unique bimodal micro-mesoporous pore size distribution mainly around 1.2 nm, 1.6 nm and 1.8 ∼ 3.5 nm, using a pluronic triblock copolymer with approximately an average molecular weight of 3858 as template by hydrothermal synthesis. The SMS possessed the characteristics of Ia3d cubic phase and super microporous as well as mesoporous silica structure, according to the X-ray diffraction characterization as well as nitrogen adsorption isotherms. The SMS could effectively reduce the diffusion resistance and exhibit improved shape selectivity compared to microporous or mesoporous silicon oxide, respectively, by virtue of its bimodal micro-mesoporous pore size distribution. Under an optimized crystallization temperature of 100 °C for 24 h, the as-synthesized SMS displayed a notable desulfurization performance with a breakthrough capacity of 0.122 mmol S/g benzothiophene, which was significantly superior to that of traditional mesoporous silica KIT-6 (0.04 mmol S/g). Furthermore, the desulfurization performance of SMS adsorbent was not significantly reduced after three cycles of regeneration. The SMS exhibited high desulfurization capacity, easy regeneration and satisfactory regeneration performance, and it could be applied in adsorptive desulfurization technology.

Highly dispersed amorphous ZnO on a petal-like porous silica-clay composite with enhanced antimicrobial properties

Nano zinc oxides (ZnO) had aroused enthusiastic attention in bacteriostasis. However, the antibacterial efficiency of the nano ZnO was greatly reduced due to agglomeration during the practical application. Herein, an effective approach to the uniform dispersion of ZnO on montmorillonite (Mt) intercalated by porous silica was reported to improve the antibacterial efficiency. A petal-like silica-clay composite (SC) loaded with ZnO (SC/ZnO) was synthesized, the appropriate ratio of Mt and TEOS to completely exfoliated the Mt sheets was explored, which was 0.88 g Mt and 2 mL TEOS. Benefiting from the microporous silica microspheres, the composites possessed a large specific surface area about 239 m2/g and well-dispersed ZnO, with a similar zinc content of Mt-ZnO about 10%. Comparatively, SC/ZnO composites showed enhanced antibacterial activity against Staphylococcus aureus with respect to Mt-ZnO. The results indicated that silica modification provided a promising strategy to improve the bacteriostatic efficiency of "metal oxide-clay" composites.

Synthesis and Characterization of Silica–Tantala Microporous Membranes for Gas Separations Fabricated Using Chemical Vapor Deposition

Composite membranes consisting of microporous tantalum-doped silica layers supported on mesoporous alumina substrates were fabricated using chemical vapor deposition (CVD) in both thermal decomposition and counter-flow oxidative deposition modes. Tetraethyl orthosilicate (TEOS) was used as the silica precursor and tantalum (V) ethoxide (TaEO) as the tantalum source. Amounts of TaEO from 0 mol% to 40 mol% were used in the CVD gas mixture and high H2 permeances above 10−7 mol m−2 s−1 Pa−1 were obtained for all conditions. Close examination was made of the H2/CH4 and O2/CH4 selectivities due to the potential use of these membranes in methane reforming or partial oxidation of methane applications. Increasing deposition temperature correlated with increasing H2/CH4 selectivity at the expense of O2/CH4 selectivity, suggesting a need to optimize membrane synthesis for a specific selectivity. Measured at 400 °C, the highest H2/CH4 selectivity of 530 resulted from thermal CVD at 650 °C, whereas the highest O2/CH4 selectivity of 6 resulted from thermal CVD at 600 °C. The analysis of the membranes attempted by elemental analysis, X-ray photoelectron spectroscopy, and X-ray absorption near-edge spectroscopy revealed that Ta was undetectable because of instrumental limitations. However, the physical properties of the membranes indicated that the Ta must have been present at least at dopant levels. It was found that the pore size of the resultant membranes increased from 0.35 nm for pure Si to 0.37 nm for a membrane prepared with 40 mol% Ta. Similarly, an increase in Ta in the feed resulted in an increase in O2/CH4 selectivity at the expense of H2/CH4 selectivity. Additionally, it resulted in a decrease in hydrothermal stability, with the membranes prepared with higher Ta suffering greater permeance and selectivity declines during 96 h of exposure to 16 mol% H2O in Ar at 650 °C.

Dimensional stabilization of wood by microporous silica aerogel using in-situ polymerization

In this paper, a method for dimensional stabilization of wood through bulk hydrophobization was investigated using a sol–gel process resulting in in-situ formation of microporous SiO2 aerogel. Two different wood species, beech (Fagus sylvatica) and Scots pine (Pinus sylvestris) were investigated. The incorporation of microporous silica aerogel inside the cell wall and lumen was verified by scanning electron microscopy, energy dispersive spectrometry and Fourier-transform infrared spectroscopy. A leaching test using paper as model material proved the bonding of the aerogel to the cellulose component of the cell wall, which indicates a long-lasting effect of the treatment. The modification of wood with silica aerogel significantly improved its hygroscopicity and dimensional stability, decreased the equilibrium moisture content and water uptake beside a low weight percent gain. Permeability was reduced as a result of the silica aerogel deposition in the macro- and micropores of the modified wood. The treatment resulted in an obvious colour change as well.

Mass transfer approaches for CO2 separation in non-isothermal and non-adiabatic pressure swing adsorption system for biomethane upgrading

The mass transfer of CO2 over solid materials can be quite complex. The complexity arises as a result of the adsorbent’s complex surface morphology and dynamic process operating conditions. In this study, a new model was proposed to predict the mass transfer behavior of CO2 over silica gel in biogas upgrading process in which three mass transfer systems (lumped, micro-/macropore, and particle) were introduced. An overview for such mathematical models for CO2 mass transfer was conducted and then a new non-adiabatic and non-isothermal model for pressure swing adsorption (PSA) that is different from the existing models in the literature, i.e., adiabatic and isothermal models, was built and assessed. The new model was executed using Aspen Adsorption and validated using experimental data reported previously over silica gel bed. The validation was performed by comparing molar fractions of CH4 and CO2, temperature profile of silica gel bed, and bio-CH4 purity and recovery with previously reported experimental data. The particle mass transfer system, which estimated the adsorption rate and gas concentration profile in the adsorbent’s particle, recorded the highest bio-CH4 purity of 99.12%. Lumped approach, which comprised mass transfer resistances in one overall resistance and ignored the dispersion effect, recorded bio-CH4 purity of 97.63% followed by micro-/macropore, which accounted micro and macropore resistance individually, with purity of 84.65%. Particle mass transfer approach yielded the highest bio-CH4 recovery of 96.745%, followed by lumped (95.41077%), and micro/macropore (82.433%) systems. Particle mass transfer was one of the most realistic systems in predicting the CO2 diffusion over silica gel due to its comprehensive heat/mass transfer consideration along with its assumption of uniform pore structure that fitted well with the true nature of the microporous silica character.

Preparation of epoxy resin foam by composite foaming agent prepared from microporous silica and 4,4′‐bisoxybenzenesulfonyl hydrazide

AbstractGenerally, foamed epoxy resin prepared by chemical method has relatively large average cell size and low cell density, resulting in low mechanical properties and poor heat resistance. In this work, a new type of composite foaming agent (CFA) was prepared by filling the chemical foaming agent 4,4′‐bisoxybenzenesulfonyl hydrazide (OBSH) into microporous silica microspheres (MSMs), and then used for epoxy resin foaming research. The effects of curing agent diethylenetriamine (DETA) and CFA contents on cell density and size were also discussed. The best epoxy resin foaming sample has a cell density of 106 cells cm−3 with an average cell diameter of 65 μm, and a high compressive strength of 34 MPa as well as a good heat resistance. These results indicate the potential application of CFA in epoxy resin foaming area.

Formation of spherical microporous silica particles from organosilane and quat molecules

The approach is developed to obtain submicron spherical particles of amorphous silica with interconnected micropores. The particles were synthesized via hydrolysis of organosilanes, i.e. tetraethoxysilane (TEOS) and (3-methacryloyloxy) propyltrimethoxysilane (MPTMOS) in a presence of quat surfactants. It was shown that the replacement of a part of TEOS with MPTMOS in the reaction mixture led to formation of particles containing only micropores instead of mesopores. At comparable amounts of MPTMOS and quat for both Cquat > CMC and Cquat < CMC the particle growth mechanism changed from aggregative to that of the layer-by-layer type. Presumably, various associates are formed in the reaction mixture from quat surfactant and MPTMOS molecules by the van der Waals and Coulomb interactions. The associates are built into the silica framework formed as a result of hydrolysis of organosilanes. After the organics are removed, a branched system of interconnected micropores 0.5 - 2 nm in size is formed within the particles at place of the associates. The synthesized microporous particles have a specific surface area of up to ~ 1000 m2 g−1 and pore volume of up to 0.5 cm3 g−1. The adsorption of transition-metal ions (Co2+, Ni2+) by the synthesized microporous particles was studied. It was shown that the adsorption capacity of microporous particles is twice that of particles with mesopores.

Deactivation Mechanisms of Engineering Adsorbents for VOCs Adsorption and the Lifetime-Prolonging Strategy

Adsorption–desorption process has been considered as a promising way for both the removal and recovery of volatile organic compounds (VOCs) from waste gases. However, during the engineering applications of the adsorbents, they would be deactivated or deteriorated. Herein, the deactivation mechanisms of different engineering VOC adsorbents (activated carbons and silica gels) by different processes or parameters have been investigated. It is found that the deactivation of adsorbents is mainly attributed to the following reasons: accumulation of VOCs in the pores, breaking of the pore structures due to the frequent-changing of processing conditions, occupation of the pores by water or other impurities, and so forth. For the temperature swing adsorption (TSA) process, the performance of adsorbents would be deteriorated by (i) the accumulation of VOCs due to incomplete desorption or (ii) the collapse of the pore structure of adsorbents (e.g., activated carbons and microporous silica gel) due to frequent cooling and heating between adsorption and desorption, respectively, leading to the deactivation of adsorbents. This phenomenon could be weakened when the pores in the adsorbents increased (e.g., the mesoporous silica gel, SG B). For the vacuum swing adsorption (VSA) process, the pore structure of adsorbents was slightly influenced during the adsorption–desorption cycles. The decrease in the adsorption capacity of adsorbents was mainly ascribed to the accumulation of VOC chemicals in the pores. In addition, in the TSA or VSA process, when the water vapor was present, the adsorption performance of adsorbents will be significantly reduced due to the occupation of adsorption sites by the water, resulting in faster deactivation. Considering the processing cost and lifetime of adsorbents, the TSA and VSA are combined together herein. The results show that, compared with the single TSA and VSA, the combined VSA–TSA process could be applied to different VOCs and improve the desorption rate of the adsorbents greatly at lower energy consumption and longer lifetime.