Narrow Pore Size Distribution Research Articles

MgH2 nanoparticles confined in reduced graphene oxide pillared with organosilica: a novel type of hydrogen storage material.

Hydrogen is a promising alternative fuel that can push forward the energy transition because of its high energy density (142 MJ kg-1), variety of potential sources, low weight and low environmental impact, but its storage for automotive applications remains a formidable challenge. MgH2, with its high gravimetric and volumetric density, presents a compelling platform for hydrogen storage; however, its utilization is hindered by the sluggish kinetics of hydrogen uptake/release and high temperature operation. Herein we show that a novel layered heterostructure of reduced graphene oxide and organosilica with high specific surface area and narrow pore size distribution can serve as a scaffold to host MgH2 nanoparticles with a narrow diameter distribution around ∼2.5 nm and superior hydrogen storage properties to bulk MgH2. Desorption studies showed that hydrogen release starts at relatively low temperature, with a maximum at 348 °C and kinetics dependent on particle size. Reversibility tests demonstrated that the dehydrogenation kinetics and re-hydrogenation capacity of the system remains stable at 1.62 wt% over four cycles at 200 °C. Our results prove that MgH2 confinement in a nanoporous scaffold is an efficient way to constrain the size of the hydride particles, avoid aggregation and improve kinetics for hydrogen release and recharging.

Enhanced CO2 Methanation over Nickel‐Based Unsupported Catalyst Synthesized by Chemical Precipitation Method

AbstractThis study investigated the catalytic CO2 methanation using nickel oxide (NiO) nanoparticles and nickel oxalate (NiC2O4) as catalysts. The NiC2O4 precursor was synthesized through a chemical precipitation reaction between nickel (II) nitrate hexahydrate (Ni(NO3)2.6H2O) and oxalic acid (H2C2O4.2H2O). Nickel oxide (NiO) nanoparticles were synthesized through thermal decomposition of NiC2O4 precursor at 450 °C in air. The samples were characterized by XRD, FTIR, BET, SEM, and EDX. The XRD and FTIR analyses revealed that the NiO nanoparticles were well‐crystallized having size 17.30 nm. The BET analysis of the NiO sample revealed mesoporous NiO nanoparticles with a specific surface area (SBET) of 29.08 m2/g and a narrow distribution of pore sizes. The catalytic performance of NiO and NiC2O4 catalysts studied for the CO2 methanation in tubular packed bed reactor at 150–550 °C and 1 atm. The reduced NiO nanoparticles exhibited more catalytic activity than the decomposed NiC2O4 catalyst. At 380 °C, 1 atm, and gas hourly space velocity (GHSV) of 9000 mL g−1 h−1, the reduced NiO nanoparticle catalyst showed high catalytic activity, with a maximum CO2 conversion of 85.54 %, 99 % CH4 selectivity, and 84.69 % CH4 yield. Furthermore, the NiO nanoparticle catalyst demonstrated excellent stability after 12 h of streaming at 380 °C.

Fouling resistance of novel amphiphilic polyampholyte membranes with varying hydrophobicity towards common foulants and cell culture media

Self-assembly is a spontaneous and scalable manufacturing method to create much-needed fouling resistant membranes with narrow pore size distributions. However, there is a limited number of self-assembled membrane chemistries that can access pore sizes below 2 nm. Novel thin film composite membranes with a selective layer manufactured from a random Polyampholyte Amphiphilic Copolymer (r-PAC) have an effective pore size of 1.5 nm, relevant to various nanofiltration and water treatment applications. This is the first study that reports the membrane performance of novel r-PAC layers, prepared with varying degrees of ionic content, in filtering several classes of foulants (oil, organics, proteins, and complex mixtures). The net neutral charge of the r-PACs used enabled steady salt rejections independent of the ionic strength of the feed. The best performing r-PAC membrane composition showed no irreversible flux decline in all fouling tests and was further tested with a realistic feed, a complex cell culture media mixture utilized in cellular agriculture. This membrane exhibited an impressive 0 % irreversible flux decline after filtering the cell culture media for 20 h while a comparable commercial membrane exhibited 90 % irreversible flux decline. The chemical stability and excellent fouling resistance behavior of these membrane materials to a broad range of feeds implies these materials can enable the filtration of feeds with extreme fouling potential in biomanufacturing, wastewater treatment, and resource recovery applications.

Preparation of novel highly stable fluorinated microporous polyketone networks through direct C–H arylation polycondensation for efficient natural gas separation

Two novel hyper-cross-linked fluorinated microporous polyketone networks (FMPN-1 and FMPN-2) with permanent porosity and narrow pore size distribution were synthesized via a facile “one-step” polycondensation between the trifluoroacetophenone-based monomers and 1,3,5-triphenylbenzene. The result polymers were investigated by FTIR, solid state NMR, EDX, XRD, TGA, SEM, and TEM et al. The geometry configurations difference of building blocks resulted in the polyketone networks exhibiting the BET special surface areas from 622 to 706 m2 g−1 and total volume from 0.58 to 0.66 cm3 g−1. What's more, ideal adsorbed solution theory (IAST) analysis showed that the two polymers possessed good C3H8/CH4, C2H6/CH4 selectivities at 298K/1 bar. Together with the excellent thermal and physicochemical stabilities, the microporous fluorinated polyketone networks obtained in this work showed promising applications in adsorption/separation for C1–C3 hydrocarbons.

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction.

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2-5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14-20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH4F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction.

Solvent-resistant isoporous membranes with tailored pore characteristics and on-demand sieving by site-selective hyper-crosslinking

Isoporous block copolymer membranes with high porosity and narrow pore size distribution have been viewed as ideal membrane platforms for precise separation of similarly sized particles or solutes. However, tailored made fabrication of solvent-resistant isoporous membranes with switchable pores and rigid pores for customizable sieving have been rarely reported. Herein, we show that site-selective hyper-crosslinking is effective and robust to prepare such membranes from polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP). The selective crosslinking in PS domains endows the membrane with excellent solvent resistance and structural stability. Since not participated in the crosslinking reaction, the P4VP brushes located in pore walls endow the crosslinked membranes with adaptive pore size, switchable permeance and tunable rejections that vary with Hansen solubility parameter of solvents. Moreover, by a facile while complete etching the P4VP from pores, the switchable performance is removed and resultant membranes show rigid pore characteristics and constant rejections. Crosslinked membranes with either switchable pores or rigid-likes pores exhibit superior long-term stability (30 days) in harsh solvents. This work presents a top-down method to construct highly stable isoporous membranes with both switchable and rigid pore characteristics from the same block copolymer, which will shed the light on precisely tailoring the pore size and pore rigidity for crosslinked isoporous membranes that will not only enable the tailored sieving but also the modelling of solvent flowing behaviours in nanopores.

Incorporation of organic photochromic molecules in mesoporous silica materials: Synthesis and applications

Abstract The ability to control the function and structure of some promising nanosystems using an external stimulus is attractive research to develop programmable and reconfigurable intelligent nanomaterials. The focal point of this review is the silicon-based nanoporous materials, and particularly the mesoporous silica materials (MSMs) class (pore size: 2–50 nm), due to their important intrinsic properties, such as high surface area, highly ordered nanostructure, narrow pore size distribution, various dimensions (one-dimensional, two-dimensional, and three-dimensional), and easily functionable. One of the most essential organic components that can be incorporated in MSMs is organic photochromic molecules (OPMs), such as azobenzene, stilbene, dithienylethenes, and spiropyrans. OPMs can be incorporated into MSMs, to form photochromic mesoporous organosilica materials (PMOMs), in two different ways: physical (non-covalent immobilization) or chemical (covalent immobilization) binding. PMOMs are considered smart nanomaterials because they have the ability to undergo reversible changes in the solid state when exposed to an external electromagnetic radiation. PMOMs have been the subject of many research studies during the last decade due to their potential applications, especially as chemosensors. This review discusses the main families of OPMs, their incorporation into MSMs using different methods, and the applications of some PMOMs as chemosensors.

The development and application of Cu@TiO2@SAPO-34 as better photocatalyst towards degradation of various pollutants

The study developed a novel Cu@TiO2@SAPO-34 nanocomposite for photocatalytic mortification of organic pollutants using modified hydrothermal synthesis. The material was characterized using XRD, BET, XPS, SEM, TEM, UV–vis, and Photoluminescence spectroscopy, confirming high pollutant absorption and photocatalytic capability. The structural analysis identified the emergence of monoclinic CuO and pure anatase phase TiO2, with ligands matching the formation of SAPO-34 at various planes of 2theta degrees. Also, species of Cu-SAPO-34 (35.43 and 65.88°) and TiO2-SAPO-34 (25.56°) were identified. The BET analysis indicated a narrow pore size distribution of 5.59 nm for Cu@TiO2@SAPO-34, with a high surface area to volume ratio of 145.7868 m2. g−1. The optical property analysis revealed that TiO2 exhibited light absorption mainly in the visible region, while Cu@TiO2@SAPO-34 exhibited early adsorption in the ultraviolet region and extended to the visible regions. This was accompanied by a concomitant decrease in band gap energy from 3.09 eV for TiO2 to 2.61 eV for Cu@TiO2@SAPO-34. The Photodegradation experiment demonstrated that TiO2 nanoparticles achieved 83 % degradation of methylene blue (MB) dye solution after 120 minutes under ultraviolet irradiation, while the Cu@TiO2@SAPO-34 composite achieved 98 % within 30 minutes. The novel nanocomposite material was further tested for real wastewater treatment, self-cleaning of the coated film, and nature of wettability, which all confirmed that the novel Cu@TiO2@SAPO-34 composite is superhydrophilic and a better photocatalyst for degrading organic contaminants. The study details the Photodegradation reaction mechanism for the Cu@TiO2@SAPO-34 nanocomposite, comparing it to TiO2 under UV–vis irradiation, and proposes a chabazite-related structure using Biovia Materials Studio 2020.

High-performance separation for ultra-low concentration nanoparticles with mesoporous silica thin membrane

Mesoporous silica thin film membrane (MSTF) emerges as an ideal ultrafiltration membrane for the removal of nanoparticles, ensuring the production of particle-free water. This is mainly ascribed to its uniform and narrow pore size distribution, having vertical nanochannels with low tortuosity, and being ultrathin, which helps enhance its selectivity and permeability. In this study, we demonstrated the potential of MSTF overlayed on macroporous anodic aluminum oxide (AAO) support for separating gold nanoparticles even at a very low concentration. Moreover, with the addition of pore-expanding agents, E-MSTF⊥AAO (pore size 3.12 nm) and D-MSTF⊥AAO (pore size 5.26 nm) membranes are formed, and both membranes indeed showed high rejection efficiency towards 150 ppb gold nanoparticles of sizes 10 nm and 5 nm, ∼99 %, and ∼96 %, respectively. It is also worth noting that as compared to the state-of-the-art conventional UF membranes, the E-MSTF⊥AAO membrane showed significantly high permeance of 114.1 ± 12.76 L m−2 h−1 bar−1 and 104.1 ± 50.6 L m−2 h−1 bar−1 while efficiently separating 150 ppb and 50 ppb 5 nm gold nanoparticles, respectively. Moreover, the promising long-term stability and chemical stability of the MSTF⊥AAO membrane paved a promising path for applying mesoporous silica membranes for effective nanoparticle separation in wastewater treatment and particle-free water production in industries.

Oriented Interpenetrating Capillary Network with Surface Engineering by Porous ZnO from Wood for Membrane Emulsification.

Membrane emulsification technology has garnered increasing interest in emulsion preparation due to controllable droplet size, narrower droplet size distribution, low energy consumption, simple process design and excellent reproducibility. Nevertheless, the pore structure and surface engineering in membrane materials design play a crucial role in achieving high-quality emulsions with high throughput simultaneously. In this work, an oriented interpenetrating capillary network composed of highly aligned and interconnected wood cell lumens has been utilized to fabricate an emulsion membrane. A novel honeycomb porous ZnO layer obtained by a seed prefabrication-hydrothermal growth method was designed to reconstruct wood channel surfaces for enhanced microfluid mixing. The results show that through the unique capillary mesh microstructure of wood, the emulsion droplets were smaller in size, had narrower pore-size distribution, and were easy to obtain under high throughput conditions. Meanwhile, a well-designed ZnO layer could further improve the emulsion quality of a wood membrane, while the emulsifying throughput is still maintained at a higher level. This demonstrates that the convection process of the microfluid in these wood capillary channels was intensified markedly. This study not only develops advanced membrane materials in emulsion preparation, but also introduces a brand-new field for functional applications of wood.

Enrichment of Nutmeg Essential Oil from Oil-in-Water Emulsions with PAN-Based Membranes.

This study used polyacrylonitrile (PAN) and heat-treated polyacrylonitrile (H-PAN) membranes to enrich nutmeg essential oils, which have more complex compositions compared with common oils. The oil rejection rate of the H-PAN membrane was higher than that of the PAN membrane for different oil concentrations of nutmeg essential oil-in-water emulsions. After heat treatment, the H-PAN membrane showed a smaller pore size, narrower pore size distribution, a rougher surface, higher hydrophilicity, and higher oleophobicity. According to the GC-MS results, the similarities of the essential oils enriched by the PAN and H-PAN membranes to those obtained by steam distillation (SD) were 0.988 and 0.990, respectively. In addition, these two membranes also exhibited higher essential oil rejection for Bupleuri Radix, Magnolia Officinalis Cortex, Caryophylli Flos, and Cinnamomi Cortex essential oil-in-water emulsions. This work could provide a reference for membrane technology for the non-destructive separation of oil with complex components from oil-in-water emulsions.

Physicochemical and Adsorption Characterization of Char Derived from Resorcinol-Formaldehyde Resin Modified with Metal Oxide/Silica Nanocomposites.

A series of metal- and silica-containing carbon-based nanocomposites were synthesized by pyrolysis of a resorcinol-formaldehyde polymer modified with metal oxide/silica nanocomposites (MxOy/SiO2, where M = Mg, Mn, Ni, Cu and Zn) via the thermal oxidative destruction of metal acetates adsorbed on highly dispersed silica (A380). The concentration of metals was 3.0 mmol/g SiO2. The phase composition and morphological, structural and textural properties of the carbon materials were analyzed by X-ray diffraction, SEM, Raman spectroscopy and low-temperature N2 adsorption. Thermal decomposition under a nitrogen atmosphere and in air was analyzed using TG-FTIR and TG-DTG-DSC techniques to determine the influence of the filler on the decomposition process. The synthesized composites show mesoporous structures with high porosity and narrow pore size distributions. It could be shown that the textural properties and the final composition of the nanocomposites depend on the metal oxide fillers of the precursors. The data obtained show that nickel and copper promote the degree of graphitization and a structural order with the highest porosity and largest specific surface area of the hybrid composites. The good adsorption properties of the obtained materials were shown for the recovery of p-chlorophenol and p-nitrophenol from aqueous solutions.

Formation of Polyimide Membranes via Non-Solvent Induced Phase Separation: Insight from Molecular Dynamics Simulations.

Molecular dynamics simulations were applied to investigate the formation of P84 polyimide membranes through the non-solvent induced phase separation (NIPS) process, considering two scenarios: one using a conventional organic solvent like n-methyl-2-pyrrolidone (NMP) and the other a greener alternative, γ-butyrolactone (GBL), with water serving as the non-solvent. Different compositions of polymer solutions were established along the binodal boundaries of the respective systems, derived from experimental cloud point data on the ternary phase diagram. The resulting polymer membranes were analyzed and compared in terms of their morphology. The wettability of their surfaces was notably affected by the polymer content in the initial casting solution and demonstrated a correlation with the Brunauer-Emmet-Teller (BET) specific surface area of the associated polymer nanostructures. The GBL solvent systems produced porous polymers qualitatively similar to those obtained with NMP, albeit with slightly narrower pore size distributions.

Effect of preparation conditions of nanocrystalline Pd/MgO catalysts on their performance in selective hydrogenation of acetylene

In the present work, an alkoxide sol-gel method was applied to prepare Pd/MgO catalysts. The sol-gel procedure was followed by supercritical drying (aerogels) or conventional drying (xerogels) in a furnace. These materials were compared with the impregnated samples. The Pd loading was 1 wt% in all the cases. The as-prepared catalysts were characterized by a set of physicochemical methods. Both the type of the Pd precursor and the preparation route were found to affect the porous structure of the materials as well as the dispersion of the palladium particles and their localization over the MgO support. Both the xerogel and incipient wetness impregnation methods lead to a narrower pore size distribution in comparison to the aerogel technique. The most dispersed particles with an average size of ∼ 2.0–2.2 nm were observed for the samples prepared by xerogel and impregnation methods. In the case of aerogel-prepared samples, metallic palladium particles possess bimodal distribution with average diameters of 4.3 and 8.4 nm. The best catalytic performance in acetylene hydrogenation to ethylene (50 % acetylene conversion at 37 °C with selectivity ∼60 %) was observed for the Pd/MgO catalyst prepared via the aerogel route using [Pd(NH3)4](NO3)2. Compared to other samples, this material is characterized by relatively weak metal-support interactions and the availability of active sites for reactants, which ensures the kinetic mode of the hydrogenation reaction (Ea = 74.9 kJ/mol).

PolyMOF interlayers modulated interfacial polymerization of ultra-thin nanofiltration membranes with efficient and stable desalination performance

Ultra-thin nanofiltration (NF) membranes exhibit excellent potential in the high-efficiency removal of ions due to their superior water permeability and selectivity. However, the stability of these membranes under pressure still poses a significant challenge. In this study, we have developed an innovative polyMOF interlayer using trimesoyl chloride (TMC) cross-linked UiO-66-NH2 (denoted as UiO-66-NH2-TMC) to bolster the construction of a pressure-resistant and ultra-thin polyamide (PA) membrane, achieving stable and high-permeance desalination performance. The introduced hydrophilic and structurally reinforced UiO-66-NH2-TMC interlayer with high pore density and narrow pore size distribution provides essential benefits: (1) it ensures a uniform distribution of amine monomers, which are critical for creating defect-free PA membranes; (2) it optimizes the diffusion of amine monomers, encouraging the formation of an ultra-thin PA membrane; and (3) it enhances the overall compatibility and structural support of the membrane, significantly improving pressure resistance. Consequently, our interlayer-modulated thin-film composite (i-TFC) membrane, with 13 nm thickness, demonstrates exceptional water permeance at 25 L m−2 h−1⋅bar−1 and maintains a high sodium sulfate (Na2SO4) rejection of 96 %. Moreover, the i-TFC membranes exhibit stable performance under pressures ranging from 2 to 10 bar, display excellent long-term operational stability over 36 h, and show an anti-fouling propensity with a notable flux recovery ratio of 81.5 %. This research offers a novel approach to polyMOF interlayer application, carving a path toward designing and fabricating ultra-thin NF membranes with efficient and stable desalination properties.

Effect of applied stress on microstructural evolution during the sintering of nanocrystalline tetragonal zirconia below 1000 °C

Microstructural evolution during the sintering of tetragonal ZrO2 nanoparticles was investigated using stress-free sintering and sinter forging. The green body prepared via gel casting had a densely packed structure with a narrow pore size distribution. Special attention was paid to the evolution of pore structures in the initial and intermediate stages of sintering. Pore coarsening, which is considered an important issue in the nanoceramics densification, was not remarkable in sinter forging. The accelerated densification rate, coupled with the retention of finer pore size than that in stress-free sintering throughout densification, lowered the sintering temperature requirement. This temperature reduction effectively inhibited grain growth, allowing samples prepared via pressure-assisted sintering to maintain a nanometric structure.

Anti-competitive adsorption of gaseous benzene on hydrophilic microporous carbon in humid conditions

The adsorption capture of ambient volatile organic compounds (VOCs) is of practical importance for air quality management. Herein, unique anti-competitive adsorption behavior of benzene on a hydrophilic activated carbon (Procarb-900 (P900)) is evidenced in the presence of competing components (e.g., formaldehyde (FA) and/or moisture). Contrary to general expectations, the adsorption capacity of 10 Pa benzene (QB) onto P900 (30 mg) at the 99 % breakthrough level improves from 144.8 to 187 mg g−1 as the relative humidity (RH) increases from 0 to 25 %. Such pattern is maintained at 183.9 mg g−1 even at the relatively high RH of 50 %. Furthermore, QB exhibits a remarkable increase of 56.1 % (to 226.0 mg g−1) in the binary phase (100 ppm benzene plus 50 ppm FA) relative to its single phase (144.8 mg g−1). The kinetic studies confirm the occurrence of anti-competitive adsorption of benzene under humid conditions with the unusual decrease in rate constants at the elevated RHs (i.e., 25 and 50 %). The thermodynamic studies suggest the exothermic nature of benzene adsorption onto P900. The hydrophilicity of P900's outer surface promotes the preferential adsorption of polar FA and water vapor over non-polar benzene, which deforms the activated carbon texture and lowers the pore size distribution (PSD). The narrow PSD enhances benzene uptake in the complex systems due to the confinement effect. Overall, this study offers insights into the unique anti-competitive adsorption of non-polar VOCs (e.g., benzene) on hydrophilic microporous adsorbents in the presence of potential interferences such as polar water vapor and FA. These findings offer a guideline for the practical implementation of adsorption techniques for gaseous VOCs in humid conditions.

Effective hierarchical ZSM‐5 catalysts for the cracking of naphtha and waste tire‐derived oil to light olefins

AbstractHierarchical ZSM‐5 zeolite materials with different SiO2/Al2O3 molar ratios in the range of 60–300 were synthesized using soft templating and microemulsion methods to generate zeolite materials with narrow mesopore size distributions. The resulting materials were characterized by X‐ray flourescence (XRF), Fourier transform infra‐red (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature programmed desorption (NH3‐TPD), thermo‐gravimetric analysis (TGA), Brunauer‐Emmett‐Teller (BET) surface area measurements, and products from the catalytic tests were analyzed by gas chromatography (GC). The XRF analysis determined that the Si/Al ratios for the synthesized ZSM‐5 were close to the batch ratios. The XRD and FTIR results revealed that the synthesized samples had crystalline ZSM‐5 zeolite structures. The small angle observed from the XRD patterns confirmed the presence of mesopores in the structure of the prepared materials. The SEM results showed that the ZSM‐5 synthesized materials had different morphologies and particle sizes, as well as worm‐like holes indicating that some macropores with average pore sizes ranging between 68 and 85 nm were successfully generated in these materials. NH3‐TPD results showed that the total acidity of the prepared materials decreased with an increase in the Si/Al (SA) ratio following this trend: SA = 71 > 177 > 345. This may be due to the decrease in the aluminum content, which is largely responsible for the formation of acidic sites in zeolites. The acid strength was found to increase with a decrease in the Si/Al ratio, highlighted by the peak shifts to higher temperatures. From the BET results, the SA = 71 was observed to have the highest SSA of 618 m2/g given by its micropore area of 103 m2/g and an external surface area of 515 m2/g. The high external surface area present in the material was due to the development of mesopores with narrow pore size distribution of approximately 6 nm indicating the success of the microemulsion method for the generation of hierarchical zeolites with well controlled pore sizes. The hierarchical ZSM‐5 catalysts were tested for the cracking of various hydrocarbon chain lengths. Low conversions, less than 10%, were obtained in the cracking of hexane; however, when cracking longer chain C12 hydrocarbons, the conversion increased remarkably to 100%. The catalyst with SA = 71 had the highest selectivity towards ethylene and propylene olefins due to its higher acidity in comparison with the other prepared catalysts. Improved activity, selectivity towards ethylene and propylene greater than 60%, and enhanced catalyst stability were demonstrated when using a hierarchical ZSM‐5 compared to the commercial catalyst in the cracking of dodecane. High selectivity towards light olefins was obtained for the cracking of waste tire‐derived oil. The results suggest that these hierarchical materials are suited to the cracking of long chain hydrocarbons and are promising materials for the valorization of waste tire‐derived oils.

Thermally induced phase separation PVDF membrane fabricated by using NaCl coagulation bath: Relation of membrane surface morphology and permeation performance

Efforts have been made in thermally induced phase separation (TIPS) process to modify the morphology of polyvinylidene fluoride (PVDF) membranes in order to improve their permeation performance and mechanical properties. Nevertheless, many methods not only altered the outer surface but also impacted the overall membrane structure, resulting in a trade-off between permeability and mechanical properties. In this study, we utilized a modified TIPS process to refine the outer surface morphology without altering the bulk structure. This was achieved by introducing NaCl in the coagulation bath. The PVDF membranes were fabricated using a dope with water insoluble diluent dimethyl phthalate (DMP) as main solvent and water-soluble additives polyethylene glycol 400 (PEG400)/triethylene glycol (TEG) as pore formers. The inclusion of NaCl in the coagulation bath serves to decrease the solubility of PEG within this medium, owing to the salting-out effect. Consequently, the NaCl concentration in the coagulation bath emerges as a crucial factor in regulating the migration of PEG400 toward the membrane surface. This control mechanism facilitates the precise adjustment of the outer surface morphology in the fabrication of membranes. As the NaCl concentration increases in the coagulation bath, the outer surface of the fabricated membrane transited from a mesh-like structure to a spherulite structure. As 0.5 mol L−1 NaCl was added to the coagulation bath, the membranes displayed a pure water permeability of 1073.9 L m−2 h−1 bar−1 while maintaining a narrow pore size distribution. Compared to the membranes fabricated without NaCl addition, the increment of the PWP contributed to the slight increase in mean pore size from 65 nm to 84 nm. Meanwhile, the water-insoluble diluent DMP was not affected by the addition of NaCl, which means that the bulk structure of the membrane could be maintained. Consequently, the increase in permeability did not compromise the mechanical properties of the membranes. All the membranes fabricated in this study maintained a reasonable tensile strength of approximately 3 MPa. This study introduces a simple and environmental method to increase the permeability effectively and fine-tune the pore size of the TIPS membranes while having little effect on the bulk structure. Furthermore, the study provides valuable insights into how changes in outer surface morphology can impact the pore size and permeability of TIPS PVDF membranes.

Utilization of rice husk substituting fossil fuel for pelletization process of goethite iron ore

The study investigated the pelletization of goethite iron ore using rice husk as a renewable carbon and energy substitute for coke breeze, which is a traditional fuel used as pellet feed in integrated steel plants. Cold Crushing Strength and porosity of the indurated pellets with rice husk addition were assessed to determine the utilization potential in the blast furnace iron making process. The X-ray diffraction studies showed the presence of iron rich magnetite and wustite, along with hematite and other oxide slag phases, which may impart high strength to the indurated pellets. FESEM studies showed the absence of free granules, which in turn confirmed the occurrence of particle-particle fusion. 3D skeleton image analyses of the indurated pellets in an X-ray micro-CT show uniform formation of round pores with good pore compactness and narrow pore size distribution inside the pellets, which are favorable properties to achieve high strength and porosity of the indurated pellets.