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Ce-promoted Ni/Mg/Al mixed oxides hydrotalcite-derived catalyst washcoated on metallic FeCrAlloy monolith was investigated in catalytic steam cracking of Vacuum Gas Oil (VGO) over a mild temperature range (300–400 °C). Hydrotalcite-derived powder solids were used as a slurry for the washcoating process were synthesized using co-precipitation and subsequent thermal decomposition. The as-fabricated catalyst exhibited over 40% VGO conversion with 46% light cut (Naphtha, Kerosene and Diesel) and 47.7% light VGO selectivity and Total Acidity Number of 0.9 mg KOH/g sample. This result seems promising for steam cracking of VGO over a novel structured catalyst. The washcoated catalyst was characterized using X-ray diffraction, surface area and X-ray Photoelectron Spectroscopy. Also, the liquid products composition/ quality and gas products composition were measured with various techniques such as simulation distillation, gas chromatography, viscosimeter and micro carbon residue.

Exfoliated 2D MAX Ti3AlC2 conductive cocatalyst anchored with g-C3N4/TiO2 to construct 2D/0D/2D heterojunction has been explored for enhanced CO2 photoreduction in a fixed-bed and monolith photoreactor. The TiO2 particle sizes (NPs and MPs) were systematically investigated to determine effective metal-support interaction with faster charge carrier separation among the composite materials. When TiO2 NPs were anchored with 2D Ti3AlC2 MAX structure, 10.44 folds higher CH4 production was observed compared to anchoring TiO2 MPs. Maximum CH4 yield rate of 2103.5 µmol g−1 h−1 achieved at selectivity 96.59% using ternary g-C3N4/TiO2/Ti3AlC2 2D/0D/2D composite which is 2.73 and 7.45 folds higher than using binary g-C3N4/Ti3AlC2 MAX and TiO2 NPs/Ti3AlC2 samples, respectively. A step-scheme (S-scheme) photocatalytic mechanism operates in this composite, suppressed the recombination of useful electron and holes and provides higher reduction potential for efficient CO2 conversion to CO and CH4. More importantly, when light intensity was increased by 5 folds, CH4 production rate was increased by 3.59 folds under visible light. The performance of composite catalyst was further investigated in a fixed-bed and monolith photoreactor and found monolithic support increased CO production by 2.64 folds, whereas, 53.99 times lower CH4 production was noticed. The lower photocatalytic activity in a monolith photoreactor was due to lower visible light penetration into the microchannels. Thus, 2D MAX Ti3AlC2 composite catalyst can be constructed for selective photocatalytic CO2 methanation under visible light in a fixed-bed photoreactor.

In this work, we report on fabricating a solid-state naked-eye sensor for targeting industrially relevant cobalt ions, using a tailor-made bimodal macro-/meso-porous polymer carbon-based monolithic cage-like template of high surface area and voluminous porosity. The solid-state sensor has concocted through the homogenous dispersion of a unique chromoionophoric ion-receptor (probe), i.e., 4-((9H-purin-6-yl)diazenyl)-6-hexylbenzene-1,3-diol (PDHBD), onto the polymer monolith. The ion-receptor anchored monolithic sensor's structural and surface morphology features are subjected to characterization by surface area analysis, electron microscopic, diffraction, and spectroscopic techniques. The monolith sensor exhibits exclusive selectivity for Co(II), with an incremental color transition from pale-orange to deep-red, for Co(II) concentrations ranging from 0-500 ppb. The influence of investigational factors is systematically studied to enhance sensor performance. The monolithic sensor reveals a maximum signal response in the pH range of 7.0-8.0, with response kinetics of ≤3 min, at 40°C≤ T ≥20°C, for Co(II). The multi-reusable solid-state sensor exhibits a superior detection and quantification limit of 0.3 and 1.0 ppb, respectively, for Co(II). The sensor proves its real-time monitoring efficiency in recovering Co(II) from environmental and industrial water samples with excellent data reproducibility. The binding mechanism of PDHBD molecules with Co(II) for exclusive ion-selectivity is studied using density functional theory.

In this paper, it was used a monolithic-type structured photoreactor with a high surface area calcined brass as a substrate for TiO2-P25. The TiO2 immobilization over the monoliths was carried out by the washcoating process. The films were characterized via XRD and diffuse reflectance. The monoliths were tested at a recirculation reactor using a solar simulator as an energy source and their efficiency was evaluated at Reactive Black 5 (RB5) textile dye photodegradation. It was investigated the effect of the impregnated catalyst mass, the monolith size, the initial dye concentration and the reaction medium pH. The preliminary tests of the brass calcination temperature (500, 600, and 700 °C) showed the formation of ZnO and CuO semiconductors at the brass surface, thus suggesting that the monoliths can act as photocatalysts. Furthermore, the brass calcined at 500 °C showed the greater formation of both oxides (ZnO and CuO) and greater photocatalytic efficiency. The TiO2/brass monolith presented more than 59 % of degradation for an initial dye concentration of 12.5 mg.L−1. In regarding to stability test, the system set forth a decrease at RB5 degradation efficiency of 62 % and presented an adherence of 77.5 % after 5 cycles of monoliths reuse. Therefore, the brass monolithic systems with immobilized TiO2 showed to be a feasible alternative for textile effluent treatment.

Structured catalysts have important advantages compared to powder formulations and they are required for processes intensification. In this work, three different ceramic structures: a cordierite monolith, an alumina foam and an alumina-silica paper were used as substrates for the deposition of a NiO-Al2O3 coating and tested in the oxidative dehydrogenation of ethane to produce ethylene. For comparison, a NiO-Al2O3 powder catalyst was also prepared. Nickel oxide species with different physicochemical features were obtained over each structure, evidenced by morphological (SEM-EDX) and physicochemical characterization (XRD, LRS and XPS). The best distributions of the catalytic coatings and NiO physicochemical properties were obtained when the monolith and the foam were used as substrates. These led to higher NiO-Al2O3 interactions and consequently to high ethylene selectivity values, 70–90 %, corresponding to the former an ethane conversion of 22 % and to the latter a 5 %. The distribution of the active phase on the ceramic paper was heterogeneous, with NiO agglomerations and poor NiO-support interaction thus achieving low olefin selectivity (∼ 30 %). The addition of a second element such as cerium was also studied in those structured catalysts with high selectivity, resulting in both cases in an increment of ethane conversion but a decrease in ethylene selectivity. This behavior was attributed to the generation of electrophilic oxygen species.

We use a multi-scale multi-mode reduced order model for coupled homogeneous-catalytic reaction systems to present a comprehensive bifurcation (ignition-extinction) analysis of the oxidative coupling of methane (OCM) in monolith, gauze or wire-mesh type reactors. We determine the impact of methane to oxygen ratio in the feed, space time, channel hydraulic radius (or gas phase to catalyst volume ratio), washcoat diffusional limitations, operating pressure and substrate thermal conductivity on the ignition and extinction behavior of the system as a function of the feed temperature. The computations show that for typical operating conditions, the methane conversion and C 2 product selectivity are non-monotonic on the ignited branch and there exists an optimum point of operation away from the extinction point. The predicted methane, oxygen conversions and C 2 selectivity are compared to reported experimental results in the literature. We also present the various species and temperature profiles along the length of the reactor and examine how these profiles are impacted by the substrate conductivity, space time and heat loss. The results obtained for monolith, gauze or wire-mesh reactors are compared to those in packed-bed reactors and suggestions are provided for scale-up and optimization of these reactors for carrying out OCM as well as other catalytic partial oxidations.

Efficiently processing volatile organic compounds (VOCs) with nonthermal plasma and honeycomb catalyst for practical industrial applications presents a sizable challenge. An attempt has been made to generate a large volume of uniform plasma at atmospheric pressure in a practical-scale honeycomb catalyst. H-ZSM-5, a type of zeolite, was washcoated on a commercial bare honeycomb monolith as the catalyst-supporting material, after which the monolith was impregnated with Pd. The plasma discharge power can be controlled by controlling the humidity in the feed gas, metal content, applied voltage, and total flow rate of the feed gas. The plasma was characterized by the voltage and current waveforms, and optical emission spectroscopy (OES). In this study, 85% of dilute toluene (15 ppm) was successfully removed from an airstream at a large flow rate of 60 L/min with an energy density of 84 J/L. Under this condition, the selectivity of CO2 was 76%. This investigation demonstrated the practical applicability of the plasma-honeycomb catalytic reactor to process a fast-flowing feed gas without resulting in a significant large pressure drop, which can hardly be achieved with typical packed-bed plasma reactors.

Separation of oil/water mixtures using monolithic porous materials is an attractive approach for absorbing a variety of polar and apolar solvents from their mixtures. In our work, we report a simple and low-cost fabrication of macroporous monolith followed by hydrophobization with adsorption of candle soot particles (CSPs). This modification makes it omniphilic and substantially enhance its hydrophobic nature by packing of CSPs into the polymeric walls of the monolith as confirmed by scanning electron micrographs. Water contact angle (WCA) and solvent absorption behaviour of CSP-adsorbed monoliths were studied and subsequently, were employed for the separation of floating oil/water mixture. Unmodified monolith S0 is hydrophilic in nature and absorbs over 30 times its weight when dipped in water. WCA study reveals that the contact angle increases systematically from 0 to ∼ 130° with an increase in CSP concentration and monolith S5 can absorb chloroform more than 38 times its weight. Monoliths possess high mechanical strength and can be used for repetitive compression/absorption cycle for solvent absorption. These high porosity sponges provide an effective strategy, high-performance controllable absorbability, and can be used as a separation tool for floating oil/water mixtures.

Coated monolith/foam catalysts are promising materials for chemistry applications due to structured reactor configuratiions providing low expansion coefficient, good thermal stability and low pressure loss. In this study, powedered Ni(0)/La2O3 catalysts in perovskite structures, were deposited on cordierite monolith substrates (2MgO-2Al2O3-5SiO2) by dip-coating method. The catalysts were characterized by N2 adsorption, XRD, TPR-H2 analysis. The activity of structured catalysts with various powder loadings (4, 8, 12, 20 and 30 wt %) were evaluated in combined Steam-CO2 reforming reaction (CH4/CO2/H2O = 2/1/2 vol%) at GHSV = 60.000 h-1. XRD and TPR results showed that the active phase LaNiO3 were mainly Ni and La2O3distributed on the surface of cordierite channels after air calcination of 850oC, 3 hours and hydrogen reduction of 600oC, 2 hours . The conversion of methane and CO2 on monolith catalysts, with proper active sites loadings of 12 – 20 wt%, were close to 80 vol% at 800oC. At the same reaction amount of active sites, the feedstock conversion on LaNiO3/monolith (12 %wt LaNiO3/monolith) was significantly higher than on corresponding powdered type, respectively 1.6 times of CH4, 1.8 times of CO2 conversion.

The possibility of using a new graphene-based carbon monolith for searching new oil deposits or branches adjacent to the already registered oilfields by areal geochemical survey is demonstrated. The material has been developed at the Faculty of Chemistry of M. V. Lomonosov Moscow State University. Sorption of volatile organic compounds (VOCs) from soil air at the oilfield was carried out using two sorbents (carbon adsorbent and Tenax-TA traditionally used for such analyses) with subsequent determination by gas chromatography with mass spectrometric detection and thermal desorption as a way of sample injection (TD/GC/MS). The new material absorbs more hydrocarbons (n-alkanes and monoaromatics) in the range from C8 to C16 than Tenax-TA, the intensities of the chromatographic peaks of the compounds also being higher. The phenomenon of irreversible sorption from carbon materials is observed for VOCs from C17 and more. However, the concentration of such substances in the soil air is rather low due to the low pressure of saturated vapors of these compounds under normal conditions. Hence, the chromatogram of carbon monolith reflects the macro-characteristics of this oil deposit better than Tenax-TA. To increase the sensitivity of the determination, a preliminary optimization of thermal desorption conditions was carried out. The values of the helium flow rate through the sorbent sample and the desorption time of the compounds are chosen to get the largest peak area. The regeneration of sorbent samples is carried out to provide the possibility of their reusage. Tenax-TA decomposes at lower temperatures compared to carbon sorbent and thus cannot be purified completely unlike the new monolith. The graphene-based sorbent is reusable and much cheaper in the manufacture than imported polymer Tenax-TA since it is made of domestic materials.

Sunflower oil hydrogenation was carried out in a 2 mm diameter jacketed capillary reactor coated with a Pd/Al2O3 catalyst, mimicking a channel of a heat exchanger monolith reactor. The operating conditions were chosen to ensure Taylor flow conditions and to evaluate their impact on the reaction selectivity. CFD simulations of the experiments were performed using the unit cell approach. They accounted for the dependence of viscosity on the degree of oil saturation, kinetic laws describing the effects of pressure on cis/trans selectivity, and bubble shrinkage along the channel using a moving mesh strategy. The model captured the experimental trends, in which the fraction of monounsaturated cis fatty acids did not exceed 35% (vs 30% originally). Poor selectivity is mainly due to the strong mass transfer resistance at the catalyst wall, either from fatty acids (favoring their complete saturation) and/or from hydrogen (due to bubble shrinkage, favoring cis to trans isomerization)

Due to the limited specific capacity of graphite anodes in lithium-ion batteries (LIBs), it is imperative to find alternatives with better performance. In this work, we propose, for the first time, a three dimensional (3D) porous metallic 5-5-8 carbon monolith with hexagonal lattice as a potential candidate. With 5-5-8 carbon nanoribbon as the building block, this material, named Hex-C558, goes beyond graphene-nanoribbon-based 3D porous carbon structures. Using first-principles calculations, we show that Hex-C558 is not only dynamically and thermally stable, but also is energetically more favorable than many other theoretically predicted carbon allotropes. More importantly, Hex-C558 is metallic with ordered ionic conducting channels and possesses a low mass density of 1.05 gcm−3, exhibiting great potential for ion-battery applications. As an anode for LIBs, Hex-C558 possesses a large specific capacity of 591 mAhg−1, low diffusion energy barrier of 0.27 eV (at low Li concentration) and 0.52 eV (at high Li concentration), a low open-circuit voltage of 0.51 V, and a small volume change of 2.4%. This work provides a new route for the design and synthesis of novel carbon materials for battery applications by using pentagon-based building units.

An investigation of the effect of catalyst separation in stratified autothermal reforming was conducted. A reactor containing two catalyst beds - a platinum group metal monolith followed by a pelletized copper-based steam reforming catalyst - was investigated under four different configurations corresponding to different distances between the catalyst beds. Heat shields were utilized in some trials to promote reactant mixing and increase radial heat transfer through the reactor. Reactor performance, as measured by conversion, hydrogen yield, and selectivity was quantified for each configuration. Results confirm that the reaction is heat transfer limited, with the short-distance, high-temperature configuration corresponding to an improved reactor performance. This was indicated by a 4–5% drop in methanol conversion as well as in the hydrogen yield and selectivity upon the addition of spacing between the catalysts. Visual inspection of the catalyst revealed suspected signs of potential degradation due to high temperatures, indicating the need for longer-duration experiments to determine the long-term effects of sustained high temperatures on catalyst performance.

The applications of silica aerogels are restricted due to their intrinsic fragile property. Polymerization of di-isocyanates can be templated onto the mesoporous surface of the –NH2 group modified silica clusters, resulting in the conformal crosslinked coating on surface of silica clusters. Aminopropyltriethoxysilane (APTES), as the silica co-precursor and amine group modification agent, is involved containing tetramethyl orthosilicate (TMOS) silica precursor, while hexamethylene diisocyanate (HDI) is incorporated as the polymer crosslinking agent. The effects of different amounts of APTES on the physicochemical properties of the resulting crosslinked aerogels are investigated. The results show that the optimized APTES/TMOS volume ratio can be determined at 0.5:1. The resulting optimal crosslinked silica aerogel possesses large BET specific surface area of 150.9 m2/g, low thermal conductivity of 0.037 W/(m·K), and the Young's modulus is as large as 18 MPa under strain of 4.2%, much higher than that in the previously published works. The polymerization reaction mechanism forming the polyurethane chains has also been proposed. In addition, the interactions between silica clusters and polymer chains are studied by molecular mechanics and molecular dynamics. The interactions are mainly dependent on non-bonding energy, and the electrostatic energy has decisive impact on the combination of silica clusters and polymer chains. The density field of C, H, N, O, and Si elements overlaps with each other, indicating that the polymer crosslinked silica aerogel maintains typical three-dimensional porous structure. The N element enriches in the region between silica clusters, further verifying the formation –CONH–(CH2)6–CONH- polyurethane chains, which is actually responsible for the much enhanced mechanical property.

Selective and durable fixed-bed catalysts are highly desirable for developing eco-efficient HPPO (hydrogen peroxide propylene oxide) process. The powder titanosilicate catalysts must be shaped before being applied in industrial processes. As the essential additives for preparing formed catalysts, binders are usually the catalytically inert components, but they would cover the surface and pore mouth of zeolite, thereby declining the accessibility of active sites. By recrystallizing the binder (silica)/Ti-MWW extrudates with the assistance of dual organic structure-directing agents, the silica binder was converted into MWW zeolite phase to form a structured binder-free Ti-MWW zeolite with Si-rich shell, which enhanced the diffusion efficiency and maintained the mechanical strength. Meanwhile, due to the partial dissolution of Si in the Ti-MWW matrix, abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO6 ones, improving the accumulation and activation ability of H2O2 inside the monolith. Successive piperidine treatment and fluoridation of the binder-free Ti-MWW further enhanced the H2O2 activation and oxygen transfer ability of the active Ti sites, and stabilized the Ti-OOH intermediate through hydrogen bond formed between the end H in Ti-OOH and the adjacent Si-F species, thus achieving a more efficient epoxidation process. Additionally, the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si-OH groups. The lifetime of the modified binder-free Ti-MWW catalyst was 2400 h with the H2O2 conversion and PO selectivity both above 99.5%.

Constrained by the unsatisfactory physical adsorption capacity and the low carbon yield from chemical activation, practical utilization of carbon materials for CO2 capture and separation (CCS) remains a huge challenge. Herein, we proposed a novel in-situ activation methodology to prepare a category of porous carbon monoliths in which the potassium ion activation sites are evenly introduced through acid-base reaction, contributing to the high carbon yield, abundant ultramicropores as well as rich nitrogen content. Tested at adsorption temperatures of 0, 25 and 40 °C, the as-prepared carbon monoliths display remarkable static CO2 uptake (7.1, 5.0 and 3.7 mmol/g, respectively) and excellent selective adsorption ability in dynamic breakthrough experiment with a binary mixture of CO2/N2 (68, 63 and 67, respectively). Along with the experiments, the CO2 adsorption mechanism was determined by calculating the adsorption density and adsorption energy on slit pore with various pore sizes and surface functionalities using grand canonical Monte Carlo (GCMC) simulation. The narrow micropores can significantly and effectively increase the CO2adsorption capacity, while the functional groups played the second role.

In this study, NH3 adsorption isotherms for a commercial vanadium-based SCR catalyst coated on a monolith substrate were obtained using a gas flow reactor over a wide range of parameters which have not been performed before in a single study. The isotherms were obtained under different conditions, where adsorption temperature, NH3 concentration, water concentration, washcoat loading, and catalyst oxidation state were varied. For this purpose, a systematic data processing method was developed, which characterizes the dispersion and delay effects in the experimental setup using a residence time distribution model, and artifacts such as NH3 adsorbed in the experimental setup and uncertainties in the washcoat loading were removed. As a result, data from different catalyst samples were integrated, and adsorption isotherms with low data spread and well-defined regions were obtained. This allows the identification of the complex nature of the catalyst and dynamics, where multiple types of adsorption sites are present. For instance, the oxidized catalyst has 50% higher NH3 storage capacity compared to the reduced state of the sample. Moreover, water reduces the NH3 storage capacity at high concentrations (5.0%), whereas at low concentration (0.5%), water increases the NH3 adsorption capacity for an oxidized catalyst. The proposed data processing method can be extended for the analysis of further phenomena in catalysts studied using gas flow reactors, complementing current methods and providing information for models with extended validity and lower parameter correlations.

Dry reforming of CH4 /CO2 provides a promising and economically feasible route for the large-scale carbon fixation; however, the coking and sintering of catalysts remain a fundamental challenge. Here we stabilize single-crystalline Ni nanoparticles at the surface of porous single-crystalline MgO monoliths and show the quantitative production of syngas from dry reforming of CH4 /CO2 . We show the complete conversion of CH4 /CO2 even only at 700 °C with excellent performance durability after a continuous operation of 500 hours. The well-defined and catalytically active Ni-MgO interfaces facilitate the reforming reaction and enhance the coking resistance. Our findings would enable an industrially and economically viable path for carbon reclamation, and the "Nanocrystal On Porous Single-crystalline Monoliths" technique could lead to stable catalyst designs for many challenging reactions.

Channeling carbon dioxide The separation of gas molecules with physisorbents can be challenging because there is often a tradeoff between capacity and selectivity. Zhou et al. report a template-free hydrothermal synthesis of the one-dimensional channel zeolite mordenite, in which some silicon was replaced by iron. Rather than forming a powder that requires further shaping, this mechanically stable material self-assembled into monoliths. Iron atoms bound in tetrahedral zeolite sites narrowed the channels and enabled the size-exclusion separation of carbon dioxide (CO 2 ) over nitrogen (N 2 ) and methane. High CO 2 uptake and highly efficient CO 2 –N 2 separation was demonstrated for both dry and humid conditions. Science , aax5776, this issue p. 315

The complete study on the synthesis of biomass waste-based activated carbon monolith from Tectona grandis leaf for supercapacitor electrode materials has been successfully studied. This study was p...

In this study, iron removal was carried out by the adsorption process as a well-known method of removing heavy metal. Natural bentonite with magnetic properties in a monolithic form or Magnetite-Bentonite-based Monolith (MBM) adsorbent was used as an adsorbent to remove Iron (II) ion from the aqueous solution. The magnetic properties of adsorbents are obtained by adding magnetite (Fe3O4), which is synthesized by the coprecipitation process. The characterization of magnetic properties was performed using the Vibrating Sample Magnetometer (VSM). VSM results showed that the magnetic particles were ferromagnetic. Adsorption efficiency, isotherm model, and adsorption kinetics were investigated in a batch system with iron solution concentration varied from 2 to 10 mg/L and magnetite loading at 2% and 5% w/w. The highest removal efficiency obtained reached 89% with a 5% magnetite loading. The best fit to the data was obtained with the Langmuir isotherm (non-linear) with maximum monolayer adsorption capacity (Qo) at 5% magnetic loading MBM adsorbent is 0.203 mg/g with Langmuir constants KL and aL are 2.055 L/g and 10.122 L/mg respectively. The pseudo-first-order (non-linear) kinetic model provides the best correlation of the experimental data with the rate of adsorption (k1) with magnetite loading 2% and 5%, respectively are 0.024 min-1 and 0.022 min-1.

In this work, we prepared a hollow Co3O4 nanoparticles (NPs) immobilized reduced graphene oxide (rGO)/carbon monolith (HCGCM) via a one-step carbonization method. The doping of nanomaterial and transition metal oxide can improve the poor conductivity and low capacitance of pure carbonaceous materials. The optimal addition concentration of polystyrene microspheres as a template provided the HCGCM composite with a hierarchical pore structure and a large specific surface area (1600 cm2/g), which is conducive to generating sufficient electroactive sites. At the same time, three dimensional (3D) interconnected pores shorten ion transport paths and reduced diffusion resistance of ions. Due to the existence of pseudocapacitive behavior, the HCGCM composite, as an electrode material working in a three-electrode system, achieved a high capacitance value of 1106 F/g at a current density of 1 A/g. In two-electrode system, the asymmetric supercapacitor had excellent stability performance and remained about 86.7% capacitance after 5000 cycles test. Moreover, it also exhibited a maximum energy density of 66.7 Wh/kg at power density of 750 W/kg. Thus, the strategy of manufacturing 3D porous electrodes is beneficial to improve the overall electrochemical performance of supercapacitors.

Recently, metal organic frameworks (MOFs) derived porous carbon (PC) was integrated with phase change materials (PCMs) to form composite with enhanced thermal conductivity and stability. However, the aggregation of PC particles during carbonization results in low utilization of supporting material and decrease of loading capacity. In this research, Cu foam monolith was decorated with highly dense nanorods (NRs) to provide numerous attached sites for PC particles. Stearic acid (SA) was then filled into the PC/NRs support to prepare a SA-based hierarchical composite (SA@PC/NRs). The hierarchical composite exhibits enhanced loading capacity (42%) and thermal conductivity (0.81W/mK) than that of referent SA@PC/CF and SA@PC, as well as improved energy storage efficiency, durability and shape-stability. The hierarchical composite PCM allows light-driven thermal energy storage with high conversion and storage efficiency, indicating its potential applications in solar-energy utilization and storage.

Noble metal-based electrocatalysts present high activities for methanol oxidation reaction (MOR), but are limited by their high cost, low stability and poor resistance to carbon monoxide (CO) poisoning. The development of active and stable non-noble metal electrocatalysts for MOR is desired, but remains a challenge. Herein, we report a simple strategy to make copper nanocrystal/nitrogen-doped carbon (Cu/N-C) monoliths, which can serve as active and robust electrodes for MOR. Copper nanocrystals were electrochemically deposited onto a conductive polyaniline hydrogel and calcined to form Cu/N-C monolith, where the active copper nanocrystals are protected by nitrogen-doped carbon. Owing to their extremely high electrical conductivity (1.25 × 105 S cm−1) and mechanical robustness, these Cu/N-C monoliths can be directly used as electrodes for MOR, without using substrates or additives. The optimal Cu/N-C (FT) @500 monolith shows a high MOR activity of 189 mA cm−2 at 0.6 V vs. SCE in alkaline methanol solution, superior to most of reported Cu-based MOR catalysts. Cu/N-C (FT)@500 also presents a better stability than Pt/C catalyst in the long-term MOR test at high current densities. Upon carbon monoxide (CO) poisoning, Cu/N-C (FT)@500 retains 96% of its MOR activity, far exceeding the performance of Pt/C catalyst (61% retention). Owing to its facile synthesis, outstanding activity, high stability and mechanical robustness, Cu/N-C (FT)@500 monolith is promising as a low-cost, efficient and CO-resistant electrocatalyst for MOR.

Deactivation of honeycomb V2O5-WO3/TiO2 catalysts by arsenic has been studied widely in coal-fired power plants but rarely in glass furnaces. In this paper, deactivated catalysts that had been used for more than 4000 h were analyzed. We maintained the catalysts in their original monolith shape to retain their adhered substance and used appropriate methods to strip the substance layer by layer. With various characterization techniques, it was determined that the adhered substance was composed almost entirely of Na2SO4 and CaSO4. We also quantified the penetration depth of arsenic visually, which was more than 370 μm. A three-stage penetration and deactivation process induced by arsenic was proposed. It was pointed out that molten and volatile As2O3 played a key role in the deactivation process, while substances in the solid state had little impact on the deep bulk of the catalyst. In this study, we proposed an integrated deactivation process consisting of adhesion, penetration, and deactivation in a honeycomb V2O5-WO3/TiO2 catalyst by arsenic in a glass furnace. Finally, we also provided guidance on alleviating the deactivation caused by arsenic. The key is to convert molten and volatile As2O3 to solid-state substances before it contacts the catalyst.

The Pickering emulsion polymerization of styrene (St), divinylbenzene (DVB) as a crosslinking agent, and sodium 4-vinyl benzene sulfonate (VBS) used for in situ surface-modification of silica nanoparticles (SNps) was investigated. At 1.0 wt% DVB, amphiphilic SNps with hydrophobic patches were formed, further self-assembling into copolymer-SNps clusters occurred. Subsequently, these clusters grow by monomer swelling to finally lead to the formation of core-shell polymer microspheres. Unlike the hydrophilic patchy SNps, at 2.0 and 3.0 wt% DVB, surface-patterned SNps with higher effective hydrophobicity do not self-assemble in the water phase but rather lead to the formation of monoliths. The polymerization mechanisms related to the formation of polymer silica-coated microspheres hybrid-materials, or percolated monoliths with bi-continuous porosity, formed by interfacially jammed emulsion gel (bijels) templates, are discussed herein.

A polyethylenimine-grafted cellulose monolith was developed for efficient bacterial capture in a continuous flow system. The amino-functionalized monolith showed superior capture capacity for high concentration of both gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacteria compared with the unmodified one. The efficiency and structural stability of the monolith were consistent during bacterial filtering at a high flow velocity. Bacteria were observed to be anchored to the skeleton surface of the monolith. The performance was attributed to the well-interconnected porous structure and strong electrostatic interaction with cells, which endowed the large surface area with retention force allowing for the local adhesion of bacteria in a flow process.

The adopted ligand type of a palladium precursor has a great influence on the microstructure, morphology and catalytic performance of obtained Pd-based monolith catalysts by a one-step method with ...

Experiments were conducted for developing an on board MOFs hydrogen storage system by cryo-adsorption in terms of adsorption equilibrium and charge/discharge characteristic of the adsorbent bed. MIL-101 was synthesized by hydrothermal method, the expanded natural graphite (ENG) and a honeycomb heat exchanging device were then introduced for monolith and heat conducting enhancement. Structural characterization and measurement of thermal conductivity were performed on the MIL-101 and its composites synthesized by mixing ENG with different mass ratios. Adsorption equilibrium data of hydrogen on the MIL-101 and MEI-01 (composite formed by adding ENG with a mass ratio 0.1) were measured at a temperature-pressure range from 77.15K to 87.15 K and 0–6 MPa. Accuracies of results predicted by Langmuirian equations were compared, Toth equation and Henry law were then employed to calculate the isosteric heat of hydrogen adsorption. Charge and discharge tests were conducted under the flow rate 20 L · m i n − 1 on a 3.2 L conformable vessel respectively filled MIL-101, MIL-101+honeycomb heat exchanging device and MEI-01. It shows that the isosteric heats on two samples are similar and are about 3.1 kJ · m o l − 1 − 7.4 kJ · m o l − 1 ; the honeycomb heat exchanging device is better on weakening the thermal effect of the adsorbent bed than adding the ENG. It suggests that employing a conformable shape vessel equipped with a honeycomb heat exchanging device is a feasible solution to an on board MOFs hydrogen storage system.

Lead halide perovskite quantum dots (PQDs) are reported as a promising branch of perovskites, which have recently emerged as a field in luminescent materials research. However, before the practical applications of PQDs can be realized, the problem of poor stability has not yet been solved. Herein, we propose a trioctylphosphine (TOP)-assisted pre-protection low-temperature solvothermal synthesis of highly stable CsPbBr3/TiO2 nanocomposites. Due to the protection of branched ligands and the lower temperature of shell formation, these TOP-modified CsPbBr3 PQDs are successfully incorporated into a TiO2 monolith without a loss of fluorescence intensity. Because the excellent nature of both parent materials is preserved in CsPbBr3/TiO2 nanocomposites, it is found that the as-prepared CsPbBr3/TiO2 nanocomposites not only display excellent photocatalytic activity but also yield improved PL stability, enabling us to build highly stable white light-emitting diodes and to photodegrade rhodamine B.

Polymeric monoliths are of great interest in a variety of applications. A new gelation approach to produce a mechanically stable polystyrene (PS) gel directly from its microemulsion is reported. To produce a PS gel, the as-prepared microemulsion is first demulsified by adding selected water-miscible organic solvents. The small PS latex particles liberated from the surfactant are assembled into a piece of bulk material at an appropriate temperature with a high degree of entanglement of the polymer chains. It is found that the d2T/η value is an important parameter to evaluate the gelation ability of the organic solvents and helps determine the gelation conditions. Finally, PS monoliths are obtained by capillary drying and their pore structures can be effectively tuned by changing the gelation time and the amount of solvent exchanged with water. This allows the controlled preparation of bulk PS artefacts with densities in the range of 0.06 to 1.14 g cm−3. This simple method of PS monolith production avoids the use of shaping tools or chemical templates, needs less energy, and is a promising alternative approach to design either integrated porous or compact polymer materials.

Aerogel technologies provide high-performance lightweight materials with unique textural characteristics such as high specific surface area and open porosity. The complete removal of liquid solvent from the wet gel without crumpling the delicate nanoporous texture is one of the significant challenges during the synthesis of aerogels. In this avenue, inspecting the effect of drying time on textural properties is conceived as a noteworthy aspect in the design and development of aerogel-based systems. Therefore, the influences of pressure and temperature on drying time during supercritical CO2 drying were investigated in this report. Results revealed that at a fixed temperature of 40 °C, the drying time was shortened significantly with increasing pressure. When the temperature and pressure were 40 °C and 25 MPa, respectively, the 60 min of drying time was adequate to completely remove the ethanol from the silica aerogel monolith, while the structure of silica aerogel remained intact. Extending the drying time from 60 to 120 min did not make any difference in terms of the silica aerogel textural properties. In conclusion, this new approach sheds light on solving the big issue of the drying time required for the complete removal of ethanol from the silica aerogel in practical application on a large scale.

Nanowires (NWs) with ultrahigh aspect ratio are good one-dimensional (1D) nano scaffolds for building functional aerogels. However, challenges still remain in exploring methods to prepare shape designable NW aerogels with high quality, and to reveal multi functions in a single NW aerogel monolith. Here, we report a general camphene freeze-drying method for preparation of various inorganic NW aerogels (e.g, Cu, hydroxylapatite, MnO2 and MnOOH NW aerogels), 2D graphene oxide nanosheet aerogels, organic polymer aerogels of polystyrene (post-synthesis) and resin (in situ polymerization) aerogels, which can be freely shaped in the frozen monolith stage. The as prepared aerogels have even distributed porosity and smooth surface. Also camphene is cheap and can be effectively recycling collected for reuse. For the Cu NW aerogel with even porosity and low density of 20 mg cm−3, multifunctional pressure/gas/photo-sensing was demonstrated. A high pressure sensitivity of 1.7 kPa−1 was achieved.

Silica phosphate/chitosan-based dendritic hyperbranched polymer doped with Er3+ ions nanocomposite (i.e. SiPhDEr3+) was prepared by a sol-gel technique in monolith and thin film forms for planar wa...

A two-stage plasma catalyst system for high-throughput NOx removal was investigated. Herein, the plasma stage involved the large-volume plasma discharge of humidified gas and was carried out in a sandwich-type honeycomb monolith reactor consisting of a commercial honeycomb catalyst (50 mm high; 93 mm in diameter) located between two parallel perforated disks that formed the electrodes. The results demonstrated that, in the plasma stage, the reduction of NOx did not occur at room temperature; instead, NO was only oxidized to NO2 and n-heptane to oxygenated hydrocarbons. The oxidation of NO and n-heptane in the honeycomb plasma discharge state was largely affected by the humidity of the feed gas. Furthermore, the oxidation of NO to NO2 occurs preferably to that of n-heptane with a tendency of the NO oxidation to decrease with increasing feed gas humidity. The reason is that the generation of O3 decreases as the amount of water vapor in the feed gas increases. Compared to the catalyst alone, the two-stage plasma catalyst system increased NOx removal by 29% at a temperature of 200 °C and an energy density of 25 J/L.

The stationary phase based on sol–gel ground silica monolith particles has been produced by one-pot polymerization method incorporation of styrene and ethylene dimethacrylate. First, the ground silica monolith particles were prepared by a sol–gel process followed by sedimentation. The particles were then subjected to modify with styrene ligand via one-pot polymerization, whereas ethylene dimethacrylate was used as the cross-linker. The glass lined stainless steel columns (1 mm internal diameter, 150 mm length) were packed with the above phase for estimation of the chromatographic performance in high-performance liquid chromatography. An average number of theoretical plates of as high as 39,300 plates/column was obtained under the optimized elution condition. The column-to-column reproducibility was proved satisfactory in separation efficiency and retention factor. The experimental results indicate that sol–gel ground silica particles prepared by an aid of one-pot modification can provide a better way for preparation of highly efficient stationary phase.

To improve the catalytic combustion performance of toluene, a series of Co–CeOx monolith catalysts were synthesized by the citric acid sol–gel method. The results showed that the introduction of Co...

In order to explore a superior washcoat material to give full play to the catalytic activity of perovskite active components on the monolithic catalysts, three novel types of LaCoO3/washcoat/cordierite monolith catalysts were prepared by a facile two-step procedure which employed the cordierite honeycomb ceramic as the monolith substrate, the nano-oxides (ZrO2, ɤ-Al2O3, TiO2) as the washcoat, and the perovskite of LaCoO3 as the active components. The blank cordierite, powdered LaCoO3, semi-manufactured monolithic catalysts (washcoat/cordierite), and manufactured monolithic catalysts (LaCoO3/washcoat/cordierite) were characterized by XRD, SEM, XPS, N2 adsorption-desorption, H2-TPR, and ultrasonic test, and their catalytic activities and catalytic stability were evaluated by the toluene oxidation test. The research results indicate that the nanoparticles coated on the cordierite substrate as the washcoat can give full play to the catalytic ability of the LaCoO3 active components and also showed high catalytic stability. However, the catalytic properties of the monolithic catalysts vary notably with the species of nano-washcoat. Among all the catalysts, the porous honeycomb surface structure, uniform distribution, high ratio of surface adsorbed oxygen, and strong reducing ability together give the LaCoO3/ZrO2/cordierite monolithic catalyst the highest catalytic activity on the oxidation of toluene at low temperature, which could be attributed to the excellent interactions of perovskite and nano-ZrO2 washcoat. Therefore, the nano-oxides, especially the nano-ZrO2, have a broad practical application potential for toluene oxidation at low temperature as the washcoat of perovskite-based monolithic catalysts.

The non-oxidative dehydrogenation of propane to propylene plays an important role in the light-olefin chemical industry. However, the conversion and selectivity remain a fundamental challenge at low temperatures. Here we create and engineer high-density Lewis acid sites at well-defined surfaces in porous single-crystalline Mo2 N and MoN monoliths to enhance the non-oxidative dehydrogenation of propane to propylene. The top-layer Mo ions with unsaturated Mo-N1/6 and Mo-N1/3 coordination structures provide high-density Lewis acid sites at the surface, leading to the effective activation of C-H bonds without the overcracking of C-C bonds during the non-oxidative dehydrogenation of propane. We demonstrate a propane conversion of ≈11 % and a propylene selectivity of ≈95 % with porous single-crystalline Mo2 N and MoN monoliths at 500 °C.

The article demonstrates the design of two solid-state sensors for the capturing of industrially relevant ultra-trace Co(II) ions using porous monolithic silica and polymer templates. The mesoporous silica reveals high surface area and voluminous pore dimensions that ensures homogeneous anchoring of 4-((5-(allylthio)-1,3,4-thiadiazol-2-yl)diazenyl)benzene-1,3-diol, as the chromoionophore. We report a first of its kind solid-state macro-/meso-porous polymer monolithic optical sensor from a monomeric chromoionophore, i.e., 2-(4-butylphenyl)diazenyl)-2-hydroxybenzylidene)hydrazine-1-carbothioamide. The monolithic solid-state sensors are characterized using HR-TEM-SAED, FE-SEM-EDAX, p-XRD, XPS, 29Si/13C CPMAS NMR, FT-IR, TGA, and BET/BJH analysis. The electron microscopic images reveal a highly ordered hexagonal mesoporous network of honeycomb pattern for silica monolith, and a long-range macroporous framework with mesoporous channels for polymer monolith. The sensors offer exclusive ion-selectivity and sensitivity for trace cobalt ions, through a concentration proportionate visual color transition, with a response kinetics of ≤ 5 min. The optimization of ion-sensing performance reveals an excellent detection limit of 0.29 and 0.15 ppb for Co(II), using silica- and polymer-based monolithic sensors, respectively. The proposed sensors are tested with industrial wastewater and spent Li-ion batteries, which reveals a superior cobalt ion capturing efficiency of ≥ 99.2% (RSD: ≤ 2.07%).

Titanium honeycomb substrates having TiO2 surface with nano- to micro-sized pores were prepared by electrochemical anodization and used to make Pt-based oxidation catalyst monoliths without conventional oxide-based washcoat layers for pre-turbocharger catalyst (PTC) applications exposed to harsh conditions under very high flow rates of exhaust gas and engine vibration. Adhesion strength and CO/C3H6 oxidation performance of the catalysts were compared with conventional washcoated FeCrAl monolith catalysts. The intermediate porous TiO2 layer formation by the anodization can dramatically enhance the catalyst adhesion strength without sacrificing the catalytic performance under GHSV (gas hourly space velocity) higher than 100,000 h−1 for PTC.