Synthesis Of Porous Materials Research Articles

Ecological Utilization of the CO2 Mineralization Using Alkaline Solid Wastes: Synthesis of Porous Materials for Sandy Soil Restoration

Ecological Utilization of the CO₂ Mineralization Using Alkaline Solid Wastes: Synthesis of Porous Materials for Sandy Soil Restoration

Capacity building in porous materials research for sustainable energy applications.

The project aimed to develop porous materials for sustainable energy applications, namely, hydrogen storage, and valorization of biomass to renewable fuels. At the core of the project was a training programme for Africa-based researchers in (i) the exploitation of renewable locally available raw materials; (ii) the use of advanced state-of-the-art techniques for the design and synthesis of porous materials (zeolites and metal-organic frameworks (MOFs)) for energy storage; and (iii) the valorization of sustainable low-value feedstock to renewable fuels. We found that compaction of the UiO-66 MOF at high pressure improves volumetric hydrogen storage capacity without any loss in gravimetric uptake, and experimentally demonstrated the temperature-dependent dynamic behaviour of UiO-66, which allowed us to propose an activation temperature of ≤ 150°C for UiO-66. Co-pelletization was used to fabricate UiO-66/nanofibre monoliths as hierarchical porous materials with enhanced usable (i.e. deliverable) hydrogen storage capacity. We clarified the use of naturally occurring kaolin as a source of silica and alumina species for zeolite synthesis. The kaolin-derived zeolite X was successfully used as a catalyst for the transesterification of Jatropha curcas oil (from non-edible biomass) to biodiesel. We also prepared porous composites (i.e. carbon/UiO-66, organoclay/UiO-66 and zeolite/carbon) that were successfully applied in electrochemical sensing.

Liquid Metal Interfacial Engineering Strategy to Synthesize All-Carbon-Linked Porous Aromatic Frameworks for the Cycloaddition of CO2 with Epoxides.

This study explores the room-temperature synthesis of porous materials and the immobilization of CO2 without the use of metals. The porous aromatic frameworks synthesized at room temperature retain the important functional group structure, and the abundance of carbon-chlorine bonds creates an excellent environment for imidazole linkage. Consequently, a catalyst conducive to the cycloaddition of carbon dioxide is obtained. Hexachloro-p-xylene is explored as the precursor, and a catalyst conducive to carbon dioxide cycloaddition is obtained. The functionalized porous aromatic frameworks (PAF-280-I/B) possess a conversion of 99.6% with a selectivity of 98.9% toward styrene carbonate (SC). The findings of this study can help mitigate the impact of greenhouse gases and enable the production of organic compounds in the circular carbonate platform, turning waste into valuable resources.

Synthesis of Porous Materials Using Magnesium Slag and Their Adsorption Performance for Lead Ions in Aqueous Solution.

Magnesium slag-based porous materials (MSBPM) were successfully synthesized using alkali activation and foaming methods as an effective adsorbent for Pb2+ in solution. The effects of foaming agent type, foaming agent dosage, alkali dosage, and water glass modulus on the properties of the MSBPM were studied, and the micromorphology and porosity of the MSBPM were observed using microscopy. The influence of pH value, initial concentration, and adsorbent dosage on the Pb2+ adsorption was investigated. The results showed that a porous material (MSBPM-H2O2) with high compressive strength (8.46 MPa) and excellent Pb2+ adsorption capacity (396.11 mg·g-1) was obtained under the optimal conditions: a H2O2 dosage of 3%, an alkali dosage of 9%, a water glass modulus of 1.3, and a liquid-solid ratio of 0.5. Another porous material (MSBPM-Al) with a compressive strength of 5.27 MPa and the Pb2+ adsorption capacity of 424.89 mg·g-1 was obtained under the optimal conditions: an aluminum powder dosage of 1.5‱, an alkali dosage of 8%, a water glass modulus of 1.0, and a liquid-solid ratio of 0.5. When the pH of the aqueous solution is 6 and the initial Pb2+ concentrations are 200~500 mg·L-1, the MSBPM-H2O2 and MSBPM-Al can remove more than 99% of Pb2+ in the solution. The adsorption process of both materials followed the Langmuir isotherm model and pseudo-second-order kinetic model, indicating that the adsorption process was a single-molecule layer chemical adsorption.

Importance of geometric parameters in modeling of porous materials – a finite element study

AbstractPorous materials consist of interconnected skeletal structure around a porous space. The skeletal structure is usually formed of a solid phase and the pores are typically filled with a fluid (liquid or gas). Porous materials are characterized by two essential geometric properties: porosity and pore size distribution (PSD), which influence their bulk mechanical properties. Porosity, which is defined in terms of the ratio between the envelope and the skeletal densities, is sufficient to describe the elastic bulk properties of porous materials. Gibson and Ashby developed a power scaling law expressing the linear relation between the elastic modulus and the relative density. The PSD describes the spatial variation of the pore sizes and has recently been shown to influence the mechanical properties of porous materials. In addition to porosity and PSD, the pore characteristics, namely pore size and shape, and pore‐wall size and shape, also determine the geometric properties that influence the bulk response of these materials. In this study, the importance of the above‐mentioned geometric parameters in the modeling of the porous materials is studied using a computational framework. The bulk mechanical response under large deformation of various porous structures with PSD based on different probability density functions (PDF) and different combinations of other geometric properties under uniaxial compression is investigated. The sensitivity of mechanical response to these geometric parameters is studied. Interdependent parameters which are significantly influential are identified. By controlling these parameters, the synthesis of porous materials can be guided and optimized.

Etching Phosphate Glass-Ceramic with Phosphoric Acid to the Recyclable Synthesis of Porous Materials

Etching Phosphate Glass-Ceramic with Phosphoric Acid to the Recyclable Synthesis of Porous Materials

What induces the dense storage of hydrogen of liquid- or solid-like density levels in carbon nanopores with sub-1 nm diameters?

Hydrogen energy is promising renewable energy and specifically, hydrogen storage is a bottleneck to commercializing hydrogen energy. Researchers have relied on the synthesis of porous materials in physisorption and lowering the H2 binding energy of hydride materials in chemisorption, all of which have been conducted in a similar manner respectively. However, the development of hydrogen storage materials applicable to onboard system isn't found yet. Hence, we examined the phenomenon of eccentric H2 storage in carbon nanopores with sub-1 nm diameters reported earlier, finding a lack of deep research on the fundamentals of this phenomenon. We formulate a hypothesis of H2 storage by intrinsic EMF (IEMF) interaction and firstly discover that in contrast to general intuition, the neutral carbon nanopore forms a significant IEMF even without an external EMF. Moreover, we confirm the difference of IEMF inside the nanopore from that outside the nanopore due to the overlap between the graphene layers and demonstrate that the resultant IEMF inside the nanopore governs the H2 storage in the carbon nanopore. This result will shed light on all the other areas related to abnormal phenomena in nanopores with sub-1 nm diameters.

Block Copolymer Self-Assembly Directed Synthesis of Porous Materials with Ordered Bicontinuous Structures and Their Potential Applications.

Porous materials with their ordered bicontinuous structures have attracted great interest owing to ordered periodic structures as well as 3D interconnected network and pore channels. Bicontinuous structures may favor efficient mass diffusion to the interior of materials, thus increasing the utilization ratio of active sites. In addition, ordered bicontinuous structures confer materials with exceptional optical and magnetic properties, including tunable photonic bandgap, negative refraction, and multiple equivalent magnetization configurations. The attractive structural advantages and physical properties have inspired people to develop strategies for preparing bicontinuous-structured porous materials. Among a few synthetic approaches, the self-assembly of block copolymers represents a versatile strategy to prepare various bicontinuous-structured functional materials with pore sizes and lattice parameters ranging from 1 to 500nm. This article overviews progress in this appealing area, with an emphasis on the synthetic strategies, the structural control (including topologies, pore sizes, and unit cell parameters), and their potential applications in energy storage and conversion, metamaterials, photonic crystals, cargo delivery and release, nanoreactors, and biomolecule selection.

Synthesis of porous materials by the modification of coal fly ash and its environmentally friendly use for the removal of heavy metals from wastewater

Wastewater is a complex mixture of many pollutants, where the high-risk pollutants are heavy metals (HMs) in industrial wastewater due to their difficult removal. In this study, the waste CFA was used as the main raw material for production of new innovated flocculants porous particles by modification of coal fly ash (CFA) using a multi-step base–acid–base (NaOH–HCl–NaOH) modification method. The morphological structure and elemental composition of the prepared MCFA were analyzed through characterization analysis, i.e., SEM, EDX, FT-IR, BET, XPS, and XRD. Results found that the surface area of the flocculant particles of MCFA was increased from 5.241 to 32.011 m2/g, which increased the adsorption process of HMs (Mn2+, Cu2+, Ni2+, and Pb2+). The maximum removal efficiencies (Re %) of MCFA for Mn2+, Cu2+, Ni2+, and Pb2+ were recorded at 94.26%, 95.88%, 71.04%, and 99.91%, respectively. The Freundlich isotherm model was fitted for the adsorption process, and the maximum adsorption amounts of MCFA for Mn2+, Cu2+, Ni2+, and Pb2+ were 558.9219, 0.4341, 210.9737, and 12.1957 mg/g, respectively. Moreover, the kinetic model indicated that physicochemical adsorption occurred between the adsorbate materials and the adsorbent.

Facile synthesis of amine-functionalized three-dimensional graphene composites for CO2 capture

Excessive emissions of carbon dioxide (CO2) cause the greenhouse effect. CO2 capture and storage has been recognized as an important solution for reducing carbon dioxide emissions and coping with global warming. The synthesis of porous materials for effective CO2 adsorption is considered to be one of the most possible methods for CO2 capture and storage at present, however, achieving selective and efficient CO2 adsorption and conversion is still quite a challenge. Herein, a series of three-dimensional graphene-based materials (3D GBMs) were synthesized by alkali metal involved method, which showed high specific surface area (477.56 m2 g−1–792.96 m2 g−1) and abundant micropore and mesopore surface structures. We demonstrated that introducing N-containing or O-containing functional groups into the carbon framework can create more surface microporous structures and active adsorption sites, and significantly enhance the CO2 adsorption performance of 3D GBMs. Furthermore, it was found that the simultaneously introduction of the two kinds of functional groups into 3D GBMs could further increase the adsorption capacity of CO2 (from 2.06 mmol g−1 to 4.79 mmol g−1). All the above results indicate the treated 3D GBMs could have a great potential as efficient adsorbent in CO2 capture and storage.

Preparation and performance for CO2 adsorption of large‐scale microporous fiber membrane based on electrostatic spinning technology

AbstractAlthough nano‐porous materials are widely used, they are still difficult to prepare in large size and expand flexibly. In this work, a new method for the synthesis of porous materials is proposed. First, the block polymers were prepared by atom transfer radical polymerization. Through electrostatic spinning, the fiber films were fabricated, then the fibers were modified by surface post‐treatment and related Friedel–Crafts alkylation reaction. The pore and CO2 adsorption properties of the porous fiber films are characterized by nitrogen adsorption–desorption isotherm. In order to improve the pore properties and CO2 adsorption properties of thin films, the additives and pretreatment process are optimized. The maximum specific surface area of the porous fiber membrane is determined to be 640 m2/g, and the CO2 adsorption capacity is high up to 36.3 wt.% (8.68 mmol/g). Moreover, the porous fiber membrane derived from this strategy is superior in the aspects of large size, convenient adjustment and simple processing, which makes up for the drawbacks of traditional porous materials. The fiber membrane obtained by this strategy has high productivity, and the fiber membrane is easy to be postprocessed, which can be integrated into functional devices, and is widely used.

Releasing the π-conjugated stack in triazine-derived porous materials for highly accessible active sites

Covalent triazine-derived porous materials, a class of nitrogen-rich porous materials, show great potential for a broad scope of applications. How to reduce or reaggregate the π-conjugated stack among the adjacent layers of covalent triazine-derived porous materials for more accessible active sites, is always the high-profile key point. Herein, we report a facile and mild cross-linking strategy between cyanuric chloride (CC) and octaphenyl polyhedral oligomeric silsesquioxane (POSS-P) to synthesize triazine-derived porous materials. Due to the steric hindrance of POSS-P, the π-stacking of CC has been released intelligently, making the constructed porous materials with good affinity and highly accessible active sites. Benefiting from these notable merits, prominently pseudocapacitive lithium storage invoking by prolonged cycling has been achieved by using triazine-derived porous materials as the organic electrode of lithium-ion batteries, with the discharge capacity of 817 mAh g−1 at the current density of 2 A g−1 after 2000 cycles. Also, these accessible active sites on triazine-derived porous materials have also been proved to be favor for high adsorption capability and fast mass transfer. This work opens a new avenue for ingenious design and simple synthesis of porous materials with more accessible active sites, further promoting their performance in energy and adsorption fields.

Polymeric Network Hierarchically Organized on Carbon Nano-onions: Block Polymerization as a Tool for the Controlled Formation of Specific Pore Diameters.

The organization of specific pores in carbonaceous three-dimensional networks is crucial for efficient electrocatalytic processes and electrochemical performance. Therefore, the synthesis of porous materials with ordered and well-defined pores is required in this field. The incorporation of carbon nanostructures into polymers can create material structures that are more ordered in comparison to those of the pristine polymers. In this study we applied polymer-templated methods of carbon material preparation, in which outer blocks of the star copolymers form the carbon skeleton, while the core part is pore-forming. Well-defined 6-star-(poly(methyl acrylate)-b-poly(4-acetoxystyrene)) dendrimers were synthesized by reversible addition–fragmentation chain-transfer polymerization. They were then transformed into poly(4-vinylphenol) derivatives (namely 6-star-(poly(methyl acrylate)-b-poly(4-vinylphenol)), subjected to polycondensation with formaldehyde, and pyrolyzed at 800 °C. Cross-linking of phenolic groups provides a polymer network that does not depolymerize by pyrolysis, unlike poly(methyl acrylate) chains. The selected star polymers were attached to carbon nano-onions (CNOs) to improve the organization of the polymer chains. Herein, the physicochemical properties of CNO-polymer hybrids, including the textural and the electrochemical properties, were compared with those of the pristine pyrolyzed polymers obtained under analogous experimental conditions. For these purposes, we used several experimental and theoretical methods, such as infrared, Raman, and X-ray photoelectron spectroscopy, nitrogen adsorption/desorption measurements, scanning and transmission electron microscopy, and electrochemical studies, including cyclic voltammetry. All of the porous materials were evaluated for use as supercapacitors.

Simultaneous conventional and microwave heating for the synthesis of adsorbents for CO2 capture: Comparative study to pristine technologies

Microwave has become an attractive technology in the valorisation of renewable biomass and in the mitigation of challenges of climate change. In this work, the synergic effects of coupling microwave and mild conventional heating conditions has been investigated in preparing engineered ultra-micropore carbons from lignocellulosic biomass. The processing conditions were systematically investigated and correlated to the physicochemical properties of activated carbons produced and their performance in post-combustion CO2 capture. The highest CO2 uptake (225 mg g−1) was achieved for the hybrid carbon produced at low temperature (600 °C) and modest microwave intensity. The synergic effect of hybrid heating was confirmed by the significant CO2 uptake increase up to 80 and 60 % for the activated carbons prepared by microwave and conventional heating, respectively. The enhanced adsorption was confirmed by cyclic regeneration up to 99 % after 16 adsorption–desorption cycles, showing a linear correlation between the surface area, micropore volume and CO2 uptake. The Pseudo-first order model accurately describes the adsorption phenomena, indicating that physisorption is the primary mechanism governing the process. The results acquired from this study highlight the process intensification in the synthesis of porous materials with comparable properties that are typically attained in conventional heating using energy intensive conditions. Additionally, this approach reveals the benefits of conventional treatment for increasing the material’s microwave susceptibility and as consequence to reduce the processing time by microwave heating. The synergic effects confirms the potential of hybrid heating for applications where fast and selective heating is paramount.

Universal low-temperature and template-free synthesis of sponge-like porous micron-sized elemental materials for high-performance lithium/potassium storage

Interconnected porous micron-sized materials can effectively enhance the ion transfer kinetics and structural stability, thus improving their rate capability and long-term lifespan, and maintaining high volumetric performance, but developing a universal and low-temperature method for the large-scale synthesis of porous materials remains a formidable challenge. Herein, we develop a universal low-temperature and template-free strategy to fabricate a series of sponge-like, interconnected porous micron-sized elements (e.g., Se, Te, Sb) through H2O2-assisted water bath. The formation mechanism of porous structure is demonstrated, originating from the non-homogeneous and continuous corrosion due to the preferential intergranular corrosion of polycrystalline particles and the soluble reaction products that do not passivate the corrosion interface. The as-obtained sponge-like porous elements present large reversible gravimetric and volumetric capacities and long stable lifespans. Specifically, the porous Te electrode delivers a high reversible capacity of 392.7 mAh g−1 (volumetric capacity: 1531.5 mAh cm−3) with 93.5% utilization ratio of active materials at 0.1 A g−1 and a long-stable lifespan with 500 cycles at 1.0 A g−1 in Li-Te batteries. Besides, in-situ TEM and ex-situ SEM observations demonstrate a small volume expansion and strong structural robustness of porous Te during cycling, stemming from its inward expansion mechanism and 3D stable interconnected porous structure. This work demonstrates a simple and universal strategy to design sponge-like porous materials for energy storage and catalysis, etc.

Efficient Shaping of Cellulose Nanocrystals Based on Allomorphic Modification: Understanding the Correlation between Morphology and Allomorphs.

Cellulose nanocrystals (CNC) are green, safe, and renewable nanomaterials with a variety of excellent performances but their morphologies are notoriously difficult to control as this is unfavorable to the diversification of the end products. Allomorphic conversion plays an important role in diversifying the morphology of CNC. However, this further complicates the prediction, design, and control of the geometric dimensions of CNC. Herein, allomorphically modified cellulose (mercerized cellulose, ethylenediamine (EDA)-treated cellulose, and ball-milled cellulose) is designed and used as the starting material for CNC isolation. Subsequently, the morphological evolution of cellulose particles during acid hydrolysis is traced by scanning electron microscopy observations. A mechanism that facilitates further understanding of CNC shaping during sulfuric acid hydrolysis is proposed. According to the CNC shaping mechanism, precise prediction, design, and efficient control of the morphology of CNC (needle-like, ribbon-like, ellipsoid, and spherical) can be realized. CNC with various morphologies are favorable for their applications, such as templating synthesis of porous materials and Pickering emulsion dispersion.

Hyper cross‐linked polymers containing amino group functionalized polyimide mixed matrix membranes for gas separation

AbstractThe design and synthesis of porous materials with novel structures and functional groups to prepare mixed matrix membranes (MMMs) is an effective way to break through trade‐off effect of membrane technology. Here, hyper cross‐linked polymers containing amino groups (HCPs‐NH2) with philic‐CO2 frame were successfully prepared for the fabrication of polyimide (PI)/HCPs‐NH2 MMMs. The separation performance of pure gas is studied in order to explore NH2 groups facilitating CO2 diffusion and transmission and enhancing CO2 permeability. Consequently, the permeability of the PI/HCPs‐NH2 MMMs toward CO2 and O2 are 77.56 Barrer and 17.91 Barrer versus pure PI film toward CO2 and O2 (62.42 Barrer and 13.85 Barrer). The selectivity for CO2/CH4 and O2/N2 pairs is 24.44 and 4.01, and the selectivity of pure PI film toward CO2/CH4 and O2/N2 pairs is 20.76 and 3.29, respectively. The permeability and selectivity of PI/HCPs‐NH2 MMMs are higher than pure PI film breaking through the trade‐off effect. Moreover, the PI/HCPs‐NH2 MMMs show better separation performance on the CO2/CH4 pair than the O2/N2 pair, indicating HCPs‐NH2 with philic‐CO2 frame plays a very important role in promoting CO2 permeability. Thus, the PI/HCPs‐NH2 MMMs have potential applications in the field of natural gas purification.

Combination of aluminum molecular rings with chemical reduction centers for iodine capture and aggregation

Presented herein is the designed synthesis of porous materials by the assembly of aluminum molecular rings with flexible pseudo-tetracarboxylic acid ligands and their application in atomically precise iodine capture and aggregation.

Synthesis of Porous Material from Coal Gasification Fine Slag Residual Carbon and Its Application in Removal of Methylene Blue.

A large amount of coal gasification slag is produced every year in China. However, most of the current disposal is into landfills, which causes serious harm to the environment. In this research, coal gasification fine slag residual carbon porous material (GFSA) was prepared using gasification fine slag foam flotation obtained carbon residue (GFSF) as raw material and an adsorbent to carry out an adsorption test on waste liquid containing methylene blue (MB). The effects of activation parameters (GFSF/KOH ratio mass ratio, activation temperature, and activation time) on the cation exchange capacity (CEC) of GFSA were investigated. The total specific surface area and pore volume of GSFA with the highest CEC were 574.02 m2/g and 0.467 cm3/g, respectively. The degree of pore formation had an important effect on CEC. The maximum adsorption capacity of GFSA on MB was 19.18 mg/g in the MB adsorption test. The effects of pH, adsorption time, amount of adsorbent, and initial MB concentration on adsorption efficiency were studied. Langmuir isotherm and quasi second-order kinetic model have a good fitting effect on the adsorption isotherm and kinetic model of MB.

Quantitative Coassembly for Precise Synthesis of Mesoporous Nanospheres with Pore Structure-Dependent Catalytic Performance.

Precise synthesis of porous materials is essential for their applications. Self-assembly is a widely used strategy for synthesizing porous materials, but quantitative control of the assembly process still remains a great challenge. Here, a quantitative coassembly approach is developed for synthesizing resin/silica composite and its derived porous spheres. The assembly behaviors of the carbon and silica precursors are regulated without surfactants and the growth kinetics of the composite spheres are quantitatively controlled. This assembly approach enables the precise control of the size and pore structures of the derived carbon spheres. These carbon spheres provide a good platform to explore the structure-performance relationships of porous materials, and demonstrate their pore structure-dependent performance in catalytic water decontamination. This work provides a simple and robust approach for precise synthesis of porous spheres and brings insights into function-oriented design of porous materials.