•Coating MOF-74 and UTSA-16 on cordierite monolith.•CO2 adsorption performance of MOF-coated monoliths.•Good CO2 capture capacity and fast kinetics for MOF-coated monoliths.
Monolithic structures ...offer a cost-effective and practical platform for scaling up gas separation processes in comparison to traditional packing systems. In this study, the immobilization of several metal-organic frameworks (MOFs) namely, MOF-74(Ni) and UTSA-16(Co) on commercial cordierite monolith (600cpsi) was investigated and their corresponding adsorptive performance in CO2 capture was assessed systematically. To gain control over crystal nucleation and growth, various bottom-up growth techniques were employed and optimized with respect to loading, thickness, and adsorption characteristics of the MOFs films. Our results indicated that the choice of suitable coating procedure depends primarily on the type of the MOF material used. It was shown that layer-by-layer technique followed by a secondary growth is a suitable method for MOF-74(Ni) film growth on the monolith walls which gives rise to ∼52wt% MOF loading, whereas for UTSA-16(Co), in-situ dip coating was found to be a promising coating method which results in ∼55wt% MOF weight gain. Moreover, the MOF-coated monoliths displayed relatively moderate CO2 adsorption capacity with fast kinetics.
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•Porous RGO/PC monoliths with novel micro-nanoscale binary structure were prepared.•Superhydrophobicity of RGO/PC monoliths was ascribed to unique porous structure.•The monoliths ...exhibited excellent capability to selectively adsorb oil from water.•The monoliths possessed stable water repellency against corrosive liquid.
Superhydrophobic and superoleophilic porous reduced graphene oxide/polycarbonate (RGO/PC) monoliths with novel micro-nanoscale binary structure were first fabricated by thermally impacted nonsolvent induced phase separation (TINIPS) method. Owing to the unique pore structure, the porous monoliths possessed high specific surface area (137.19m2/g) and porosity (91.3%). The superhydrophobic RGO/PC monoliths exhibited excellent capability to selectively adsorb a wide range of oils and organic solvents from water. Furthermore, the monoliths could keep a stable repellency against corrosive mediums (e.g., acidic and alkali solutions). Based on these superior properties, porous RGO/PC monoliths will be a promising candidate for high-efficiency oil/water separation to deal with water pollution.
Direct air capture (DAC) removes CO2 from the atmosphere and can therefore address sizable nonpoint sources emissions of CO2 such as those from transportation. We propose a five-step temperature ...vacuum swing adsorption process for direct air capture using solid adsorbents coated as films on monolithic contactors using steam as the stripping agent during desorption. We perform a modeling study and economic assessment for DAC using two metal organic frameworks, MIL-101(Cr)-PEI-800 and mmen-Mg2(dobpdc), for which we have experimentally demonstrated film growth on monolith structures. The results indicate minimum energy requirements, and cost estimates are 0.145 MJ/mol-CO2 and $75–140/t-CO2 for MIL-101(Cr)-PEI-800, and 0.113 MJ/mol-CO2 and $60–190/t-CO2 for mmen-Mg2(dobpdc), respectively. The overall DAC cost is sensitive to adsorbent purchase cost and lifetime as well as cycle parameters such as adsorption and desorption times. We conclude that mmen-Mg2(dobpdc) has better performance compared to MIL-101(Cr)-PEI-800 in terms of energy requirements because of its higher capacity and nonlinear isotherm.
The development of monolith catalysts with high reusability for the advanced oxidation processes targeting water-pollution remains a big challenge. In this work, we prepared a series of Cu-based ...monolith catalysts by simply calcining metallic Cu foam or Cu sheet under different temperatures. Performance of the monolith catalysts was evaluated in degradation of Methylene Blue or Orange II with peroxymonosulfate as oxidant. The monolith catalyst is more efficient at higher pH of the reaction medium, and can be used at least 20 cycles without loss of the degradation activity. Based on the characterizations of XRD, XPS and EPR, the active composition of the catalysts for the degradation is ascribed to CuO, and the active radicals generated during the degradation process are speculated to be O2•–, ·OH, SO4•– and 1O2.
•Monolithic metal catalysts for advanced oxidation processes are desirable.•Monolith Cu-based catalysts were prepared through facile calcination in air.•Monolith catalyst was reused at least 20 times while keeping its origin activity in dye degradation.•CuO composition played an important part in producing active species for degradation reactions.
Considerable research has been conducted on monolithic catalysts for various applications. Strategies toward coating monoliths are of equal interest and importance. In this paper, the preparation of ...monoliths and monolithic catalysts have been summarized. More specifically, a brief explanation for the manufacturing of ceramic and metallic monoliths has been provided. Also, different methods for coating γ-alumina, as a secondary support, are included. Techniques used to deposit metal-based species, zeolites and carbon onto monoliths are discussed. Furthermore, monoliths extruded with metal oxides, zeolites and carbon are described. The main foci are on the reasoning and understanding behind the preparation of monolithic catalysts. Ideas and concerns are also contributed to encourage better approaches when designing these catalysts. More importantly, the relevance of monolithic structures to reactions, such as the selective oxidation of alkanes, catalytic combustion for power generation and the preferential oxidation of carbon monoxide, has been described.
In this work, a novel NH2-MIL-53(Al) incorporated poly(styrene-divinylbenzene-methacrylic acid) (poly(St-DVB-MAA)) monolith was prepared via chemical fabrication. Moreover, it has been efficiently ...applied to the in-tube solid-phase microextraction (SPME) for online coupling with high-performance liquid chromatography (HPLC) to the direct determination of five estrogens in human urine samples. The NH2-MIL-53(Al)-polymer monolith was suitable for in-tube SPME owing to its good permeability, high extraction efficiency, chemical stability, good reproducibility and long lifetime. The extraction conditions including extraction solvent, pH of sample solution, flow rate of extraction and desorption, and desorption volume were investigated. Under the optimum conditions, the enrichment factors were 180–304 and saturated amounts of extraction were 2326–21393 pmol for estriol, 17β-estradiol, estrone, ethinyl estradiol and progesterone, respectively. The adsorption mechanism was also explored which contributed to its strong extraction to target compounds. The proposed method had low limit of detection (2.0–40ng/L) and good linearity (with R2 between 0.9908 and 0.9978). Four endogenous estrogens were detected in urine samples and the recoveries of all five analytes were ranged from 75.1–120% with relative standard deviations (RSDs) less than 8.7%. The results showed that the proposed online SPME-HPLC method based on NH2-MIL-53(Al)-polymer monolithic column was highly sensitive for directly monitoring trace amount of estrogens in human urine sample.
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•A NH2-MIL-53(Al) polymer monolith column prepared by in situ polymerization.•The monolithic column showed high extraction capacity to estrogens.•An in-tube SPME for online coupled to HPLC method was developed.•The method applied to directly online sensitive analysis of estrogens in urine.
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•A method is developed to shape COF powder into monoliths.•The crystallinity and micropore of COF in monolith are well remained.•COF-based monoliths feature a hierarchically porous ...structure.•COF-based monoliths exhibit good removal performance for bisphenol A.
Subject to synthetic conditions, covalent organic frameworks (COFs) are usually in powder form. Herein, taking an azine-linked COF as an example, detailed characterizations indicated that accessible aldehyde groups and hydrazine groups (CNNH2, 88 μmol g−1) concurrently existed on its surface. Intrigued by such feature, we have developed an approach based on ring-opening polymerization to shape COF powder into monoliths. The crystallinity and micropore of COF in monoliths were well remained, meanwhile, the ring-opening polymerization remarkably generated macropores ranging from 0.43 to 3.51 μm, indicating a hierarchically porous structure. The BET surface area of resultant monoliths with different COF mass fractions of 16%, 28% and 43% ranged from 105 to 281 m2 g−1. Due to the π–π interaction and hydrogen bond interaction, COF-based monoliths exhibited strong retention and rapid adsorption for bisphenol A (BPA) in aqueous medium. When 29 mL BPA solution (22.8 mg L−1) passed through COF-based monolith (28%), the adsorption capacity was up to 61.3 mg g−1. Furthermore, the COF-based monolith demonstrated excellent cycle use for catalyzing Suzuki-Miyaura coupling reaction after being coordinated with palladium acetate.
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•Graphene-based monolith (GBM) was made using magnesium ascorbyl phosphate (MAP).•MAP-GBM could effectively remove low concentration of BPA through column adsorption.•The adsorption ...mechanisms of BPA onto MAP-GBM were deeply discussed.
In this study, a non-shell graphene-based monolith (GBM) with huge surface area was synthesized by chemical reduction of Graphene oxide (GO) using magnesium ascorbyl phosphate (MAP), and tested as an adsorbent for trace Bisphenol A (BPA) removal. The properties of MAP-GBM was characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller N2 specific surface area (BET), X-ray powder diffraction, Fourier transform-infrared (FTIR), Raman, and X-ray photoelectron spectroscopies. BPA adsorption was investigated in batch and column adsorption experiments. The data showed that MAP-GBM was a three-dimensional (3D) graphene material with macrostructure and most CC double bonds were recovered. Adsorption isotherms and kinetics of BPA on MAP-GBM followed the Langmuir model and fitted well with a pseudo-second-order kinetic model, respectively, and the adsorption process was endothermic. The saturated adsorption capacity of MAP-GBM was 324 mg/g for BPA, which was 2.43 times of that of ascorbic acid-GBM. A MAP-GBM adsorption column completely removed BPA from solution at low concentration (50 μg/L) for ∼450 mL.This efficiency is much higher than traditional adsorbents such as activated carbon, which could be ascribed to the unique 3D porous structure, hydrogen bonding, and π-π interaction characteristics of this MAP-GBM. The material can be easily regenerated by simply immersing in methanol for 24 h, and the adsorption efficiency remain as high as 88% after five regenerations. These findings demonstrated that MAP-GBM is a promising adsorbent for the effective and cost-efficient removal of low concentration endocrine-disrupting chemicals.
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•Water-tolerant Pd/CeO2 catalysts were prepared by simple heat treatment of ceria.•Surface defect, surface oxygen, and basicity of ceria were tuned by heat treatment.•Defect removal ...and surface oxygen formation prevent deactivation by water poisoning.•Pd/CeO2(900) monolithic catalyst showed excellent durability in humid condition.•Bench-scale Pd/CeO2(900) monolith has high potential for practical O3 decomposition.
Durability is a crucial requirement in heterogeneous catalysis; however, many catalysts suffer from severe deactivation in humid conditions due to water poisoning. Ozone, as a significant air pollutant, should be efficiently removed through catalytic decomposition, making it imperative to develop a water-tolerant monolithic catalyst for practical air purification. In this study, we present highly durable Pd/CeO2 monolithic catalysts resistant to water poisoning achieved through a simple heat treatment of the ceria support. The heat treatment controlled the ceria surface properties, including oxygen vacancy defects, surface oxygen, and basicity, thereby improving resistance to water poisoning. When Pd/CeO2 monolithic catalysts were used in bench-scale ozone decomposition under humid conditions, the catalyst heat-treated at 900 °C exhibited superior performance without experiencing deactivation due to water poisoning. Modulating the ceria surface properties plays a pivotal role in enhancing water resistance, and heat-treated Pd/CeO2 monolithic catalysts stand as a promising candidate for practical ozone decomposition in air purification applications.
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