N2 Adsorption Desorption Research Articles

Management of caffeine in wastewater using MOF and perovskite materials: optimization, kinetics, and adsorption isotherm modelling

Pharmaceuticals and personal care products (PPCPs) have been increasingly used all over the world and they have been reported on water cycle and cause contamination. Among these pharmaceuticals is caffeine (CAF). In this work, CAF removal from aqueous samples by metal–organic framework (UIO-66) and perovskite (La0.7Sr0.3FeO3) was achieved. Detailed studies on the preparation of MOFs and perovskite oxides compounds have been presented. Extensive characterizations such as X-Ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared spectra (FT-IR), N2 adsorption–desorption isotherms were also carried out to assure proper formation and to better understand the physico-chemical behavior of the synthesized samples before and after adsorption. Batch experiments of CAF adsorption onto both MOFs and perovskite were performed to compare the effectiveness of both materials on the removal competence of the CAF residue at different conditions including the effect of pH, initial concentration, and contact time. It was observed that the adsorption capacity of CAF by MOF increased with increasing acidity. On the other hand, the adsorption capacity of perovskite is stable in pH 4–10. The maximum adsorption capacities of UiO-66 and perovskite toward CAF are high as 62.5 mg g−1 and 35.25 mg g−1, respectively. Equilibrium isotherms were investigated by numerous models: Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, Langmuir-Freundlich, Toth, Kahn, Baudu, and Fritz Schlunder. Moreover, the kinetics of the CAF@MOF and CAF@Perovskite systems have been studied by five kinetic models (Pseudo-1st -order (PFO), Pseudo-2nd -order (PSO), Mixed 1st, 2nd-order, Intraparticle diffusion and Avrami). The best model described the adsorption of CAF onto both of MOF and perovskite was the mixed 1st, 2nd-order model. The metal–organic framework and perovskite were applied to quickly extract CAF from water samples successfully. The maximum removal percentage obtained for MOF and perovskite was 0.89% and 0.94% respectively within 30 min contact time which suggests that these materials are considered as promising adsorbents for CAF.

Impact of VAPO molecular sieve configuration on catalytic oxidation of ethyl lactate to ethyl pyruvate and its reaction mechanism

The presence of the template agent within the pore or cage during the synthesis process of the molecular sieve plays a crucial role in the formation of its porous structure. Using triethylamine and diisopropylamine as structure-guiding agents, VAPO molecular sieve with AFI and AEL topologies were synthesized by hydrothermal method. The physical and chemical properties of hierarchical VAPO-5 and VAPO-11 molecular sieves were characterized by XRD, SEM, N2-adsorption desorption, UV–Vis, XPS, NH3-TPD and Py-IR, etc. It was verified that V isomorphically displaced the P-site of the molecular sieve in pentavalent form, and more acid sites were obtained on the surface of VAPO-5 molecular sieve. This is closely related to the performance of the catalytic oxidation of ethyl lactate to ethyl pyruvate. The activity evaluation showed that the VAPO-5 molecular sieve outperformed the VAPO-11 molecular sieve in terms of catalytic performance. The theoretical study on the reaction mechanism showed that the rate-determining step energy barriers of the catalytic oxidation of EL to EP were 118.7 kJ/mol and 150.18 kJ/mol, respectively. They were consistent with the apparent activation energies of 98.92 kJ/mol and 119.24 kJ/mol obtained by kinetic experiments. The conjecture of the reaction mechanism was confirmed in which the VAPO molecular sieve adsorbs H2O2 molecules and produces surface reactive oxygen species, thus promoting the catalytic oxidation of EL to EP.

Alkylation of Phenol with Methanol over ZSM‐5 Zeolite

AbstractThe catalytic performance of different molecular sieves in the alkylation of phenol with methanol to produce p‐cresol was evaluated, and the acidity and structure of the catalysts were characterized using N2 adsorption–desorption and Fourier transform infrared spectroscopy techniques. It was shown that the catalytic activity of molecular sieves was closely related to their acidic site number, specific surface area, and pore structure. Since Zeolite ZSM‐5 (Zeolites Socony Mobil No. 5) has a relatively small amount of strong acid as well as a small pore size, it is favorable for the diffusion of p‐cresol out of the pores. Therefore, focusing on ZSM‐5, the effects of operating conditions such as weight hourly space velocity (WHSV), phenol/methanol (P/M) ratio, and reaction temperature on the catalytic performance were investigated. The results showed that increasing the WHSV, P/M ratio, and reaction temperature improved the selectivity to cresol. In addition, X‐ray diffraction and Thermal Gravity/Differential Thermal Gravity characterization methods were also carried out for ZSM‐5, and it was found that the deactivation of ZSM‐5 was due to coke deposition and pore blockage on the active site and that the selectivity to cresol could be restored by regenerating the catalyst and covering the strong acid site, which resulted in the reduction of the strong acid site to increase the selectivity of the product.

In situ synthesis of porous metal-organic frameworks NH2-UiO-66 on tea stem biochar and application in odours adsorption

Multiple odour nuisance in livestock farming is a notorious problem that has a significant impact on the living environment of surrounding communities. Adsorbents based on metal-organic framework (MOF) materials show great promise for controlling odour pollution, as they offer a high specific surface area, a controllable structure and an abundance of active sites. However, the MOF formation process is prone to problems such as pore clogging or collapse and reduced porosity, which limits its further application. In this study, a series of odour adsorbents were prepared by in situ growth of NH2-UiO-66 on tea stem biochar (TSBC) using a hydrothermal method and named UiO (Zr)-TSBCx. The physical and chemical properties and composition of UiO (Zr)-TSBCx have been systematically characterized using SEM, TEM, XRD, FT-IR, N2 adsorption-desorption and XPS. The release of odours from the pig farm effluent was monitored using in-situ continuous Proton-Transfer-Reaction Mass Spectrometry (PTR-MS), and the obtained primary compositions were tested for further adsorption. In dynamic adsorption experiments focused on butyric acid, UiO (Zr)-TSBC2 showed a high adsorption capacity of 3.99 × 105 μg/g and exceptional structural stability. UiO (Zr)-TSBC2 showed variable adsorption efficiencies for different odorous gases, with the best performance for the removal of ammonia, toluene and butyric acid. It also demonstrated the ability to rapidly mitigate instantaneous high concentrations of hydrogen sulfide (H2S), methanethiol and toluene resulting from agitation. Additionally, based on the relationship between the adsorption amount and the structural characteristics of the adsorbent as well as the nature of the odours, a possible adsorption mechanism of UiO (Zr)-TSBC2 for a variety of odours released from pig farm effluent was proposed. This work demonstrates a novel approach to promote deodorization applications in livestock and poultry farming environments by the in-situ growth of NH2-UiO-66 on biochar prepared from tea stem.

Modification of new magnetic nanocomposites Bi2WO6/CuFe2O4 and its excellent catalytic reduction for toxic nitroaromatic compounds and chromium (VI)

New magnetic Bi2WO6/CuFe2O4 nanocomposites were synthesized using hydrothermal method. The specific features of Bi2WO6/CuFe2O4 nanocomposites were studied using various analytical techniques such as Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and N2 adsorption desorption analyses, Brunauer-Emmett-Teller (BET). The BET analysis demonstrates that embedded CuFe2O4 nanoparticles in Bi2WO6 structure have increased the pore diameters and surface area for better adsorption of NaBH4 and catalytic performance. The VSM analysis confirms the magnetic behavior of nanocomposite which showed that Bi2WO6/CuFe2O4 could be separated and recoverd easily by an external magnet after catalytic reactions. The catalytic performance of nanocomposites was investigated for the reduction of nitroaromatic compounds including 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA) and 2-nitrophenol (2-NP) and chromium (VI) in aqueous solution. The results show the nanocomposites have excellent ability to reduces Cr(VI) to Cr(III) and nitroaromatic compounds to the corresponding amines in green water solution at room temperature. The best performance observed for the 100% conversion of 4-nitrophenol reduction belongs to Bi2WO6/CuFe2O4 20%, which completes in 6 min, and its rate constant is about 0.67 min−1. In addition, the Bi2WO6/CuFe2O4 nanocomposite can be appropriately recycled and reused several times without changing its structure and activity, which is essential for practical applications.

One-pot synthesis of quinazolinone heterocyclic compounds using functionalized SBA-15 with natural material ellagic acid as a novel nanocatalyst

The nanoporous compound SBA-15 was functionalized using (3-aminopropyl)trimethoxysilane (APTES). Then the obtained product was modified with ellagic acid (ELA), a bioactive polyphenolic compound. The structure of the prepared nanoporous composition SBA-15@ELA was extensively characterized and confirmed by various techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, Energy dispersive X-ray (EDX) elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption–desorption isotherms (BET). The novel, recoverable, heterogenous SBA-15@ELA nanoporous compound was used to investigate its catalytic effect in the synthesis of 4-oxo-quinazoline derivatives (19 examples) with high yields (78–96%), as an important class of nitrogen-containing heterocyclic compounds. The use of an inexpensive mesoporous catalyst with a high surface area, along with easy recovery by simple filtration are among the advantages of this catalysis research work. The catalyst has been used in at least 6 consecutive runs without a significant loss of its activity.

Feasibility study of replacing part of cement by igneous rock powder as cementitious material: based on mortar macroscopic properties and microstructure

To address the increasing demand for cement and promote sustainable development, the utilization of igneous rock powder as a supplementary material to partially replace cement has emerged as an effective strategy. In this study, the fluidity and mechanical properties of the igneous rock powder-cement (IRP-OPC) composite system were investigated, and the hydration product and microstructure of IRP-OPC were analyzed by using TG/DSC, N2 adsorption-desorption curve (BET) and SEM. The experimental findings demonstrate that the performance of the andesite powder-cement composite cementing system (AP-OPC) surpasses that of tuff powder-cement slurry (TP-OPC) and granite powder-cement slurry (GP-OPC). When the dosage of andesite powder (AP) is 5%–15%, the flowability, flexural strength and compressive strength of cement mortar are improved. When the dosage is 10%, the 28-day compressive strength is 48.3 MPa. Under the condition of low content (10%), part of Ca(OH)2 is fully consumed by active SiO2 in AP and reacts to form C-S-H. Hydration products and AP particles with small particle size are filled into the structural gap, which refines the pore structure of cement slurry, and the increase in compactness provides support for the development of strength in the later stage. The use of 5%–15% AP instead of OPC can improve fluidity and meet the strength requirements of P.O 42.5 Portland cement. This substitution not only reduces engineering costs but also enhances resource utilization.

Construction of Bi2WO6/g-C3N4/Cu foam as 3D Z-scheme photocatalyst for photocatalytic CO2 reduction

Photocatalytic CO2 reduction to hydrocarbon fuels represents a promising solution to CO2 emission challenges. However, photocatalytic CO2 reduction systems face hurdles in practical utilization for the low efficiency of photocatalysts and challenge in catalyst immobilization. Therefore, a novel monolithic three-dimensional Z-scheme photocatalyst was synthesized by fabricating Bi2WO6/g-C3N4 heterojunction on Cu foam substrate (Bi2WO6/g-C3N4/Cu foam) via thermal polymerization and electrophoresis deposition. A series of characterization results, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and N2 adsorption–desorption, illustrate the crystalline properties, pore structure, and morphology of the composite photocatalyst. Consequently, Bi2WO6/g-C3N4/Cu foam achieved CO production yield of 33.84 μmol/g cat under visible light illumination for 6 h and retained 96.2 % of initial photocatalytic activity after 30 h of reaction. UV–Vis diffuse reflection spectra, photoluminescence spectra and photoelectrochemical analysis was involved to reveal the mechanism of the photocatalytic activity of composite photocatalyst.The synergistic effect of the Z-scheme mechanism and the hierarchical macroporous structure improves the light absorption, light-induced electron-hole pair separation, and charge transmission. This catalyst construction strategy provides a viable approach for facilitating practical photocatalytic CO2 reduction.

Synergy between Fe-Co oxide catalysts supported over HZSM-5 for direct conversion of methane to methanol

The direct conversion of methane to methanol over iron and cobalt oxide based composite catalysts supported over HZSM-5 was carried out in a fixed-bed micro reactor under changing process parameters and catalyst compositions. The prepared catalysts were well characterized by various techniques including N2 adsorption desorption, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), pyridine FTIR, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and temperature programmed reduction (H2-TPR). The characterization results revealed the presence of various reducible iron and cobalt oxide species depending on the Fe/Co molar ratio and total metal oxide loading. Moreover, the XPS and UV–vis spectroscopic results also confirmed the variation of Fe2+/Fe3+ and Co2+/Co3+ species depending on the Fe-Co molar ratio which had strong influence on the performance of the composite catalysts. It was found that the cobalt species favours the formaldehyde formation whereas the iron species promotes the formic acid formation in their respective pure supported oxide catalysts. However, the synergistic effect of iron and cobalt oxide in equimolar ratio in composite catalysts appeared as effective for achieving highest yield of methanol. The methanol selectivity was also influenced by the alteration of various studied process parameters. The higher reaction temperature favoured the overoxidation of methanol to CO2 whereas the methanol selectivity increased with increasing the methane to oxygen ratio. The lattice to adsorbed oxygen ratio also had strong influence on the activity of composite catalysts and methanol selectivity. The highest methanol yield of 1.87% was achieved at the methane conversion of 42.81 % with the 20Fe1Co1Z catalyst at 873 K reaction temperature with CH4/O2 ratio of 2:1 and WHSV of 1030 ml hr−1 gcat−1.

Degradation of TCH by Fe3O4/B4C catalyzed heterogeneous Fenton oxidation

In this work, Fe3O4/B4C (FeB) composites were successfully prepared by a facile co-precipitation process. FeB composites were characterized using XRD, FTIR, N2 adsorption-desorption, XPS, etc techniques and then used as heterogeneous Fenton catalysts to activate green oxidant (H2O2) for the degradation of TCH. The removal efficiency of TCH by FeB composites was explored including different parameters of Fe3O4 loading on B4C, catalyst dosage, initial solution pH, H2O2 dosage, and reaction temperature. The highest photo-Fenton catalytic efficiency was obtained for the composites with a mass ratio of Fe3O4 to B4C of 1:0.75. At this time, the removal efficiency of Fe3O4/B4C was 2 times and 391 times that of the parent Fe3O4 and B4C, respectively, and B4C can effectively improve the efficiency of the Fenton cycle. h+, e-, and ·OH were mainly responsible for the degradation of TCH by Fe1B0.75 composites. After repeated use for five times, the removal efficiency of the catalyst was reduced by only 8.0%. The disparity in work functions by density functional theory calculations confirmed the formation of an internal electric field at the Fe3O4/B4C composites interface, which contributed the transfer of charge carriers between the Fe3O4 and B4C. Moreover, the FeB composite showed a high stability, indicating that FeB composites may be a promising heterogeneous catalyst.

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

Noble metal modified copper-exchanged mordenite zeolite (Cu-ex-MOR) catalysts for catalyzing the methane efficient gas-phase synthesis methanol

Copper mordenite catalysts are key for methane oxidation to methanol, yet lack sufficient activity. In this paper, noble metal (Au, Ru, Pt and Pd) modified copper ion-exchanged mordenite catalysts were prepared by the ion-exchange method for further improving the methanol yield in the gas-phase continuous catalytic direct partial oxidation of methane to methanol reaction, and the role of noble metal doping on Cu-ex-MOR catalysts was investigated. Experimental results showed that the doping of Ru resulted in a significant increase in the methanol yield of Ru/Cu-ex-MOR catalyst to 157.36 μmol/gcat/h compared to that of Cu-ex-MOR catalyst (12.89 μmol/gcat/h). SEM, XRD, FT-IR, N2 adsorption-desorption, XPS, NH3-TPD and H2-TPR results showed that Ru/Cu-ex-MOR had uniformly dispersed Ru elements and the largest number of surface acidic and oxidation sites, which facilitated the adsorption and activation of methane. Additionally, it was found by TEM, in situ FT-IR and DFT characterization that Ru played a role in stabilizing the Cu active sites, the adsorptive activation of water on the Ru site and the H-transfer process reduced the energy required for breaking C–H bond of CH4 at the Cu active site, which significantly improved the methane activation capacity of the Ru/Cu-ex-MOR catalysts, resulting in higher methanol yields.

Influence of nickel contents on synthesis gas production over nickel-based catalysts supported by treated activated carbon in dry reforming of methane

This study focuses on the utilization of activated carbon (AC) as a catalyst support after undergoing treatment with HNO3. The treated AC exhibited a microporous structure and a high specific surface area (SBET) of 1483.8 m2 g−1. In this study, supported nickel-based catalysts were synthesized using the wet impregnation method with varying amounts of NiO (2.5, 5, 7.5, 10, 12.5, and 15 wt%). The calcined catalyst samples were then evaluated for their performance in the dry reforming of methane (DRM). Characterization of the catalysts was conducted through FESEM, TPO, H2-TPR, XRD, and N2 adsorption-desorption (BET) analyses. The results revealed that catalytic efficiency increased with an increase in the nickel loading percentage, up to 12.5 wt%. The NiO (12.5)/AC catalyst demonstrated the highest CH4 (60%) and CO2 (68%) conversions and exhibited good stability at 700 °C during 10 h of reaction. Additionally, the catalyst's efficiency decreased with an increase in the calcination temperature from 400 to 600 °C. However, alterations in the CH4/CO2 molar ratio from 0.5 to 1.5 indicated that CH4 and CO2 conversions decreased from 85% to 40% and increased from 63% to 74% at 700 °C, respectively. Moreover, the findings demonstrated that elevating the gas hourly space velocity (GHSV) from 12,000 to 18,000 ml h−1.g−1cat resulted in a decline in catalytic efficiency at a temperature of 700 °C. Moreover, the catalytic efficiency declined with an increase in the reduction temperature from 500 to 600 °C.

Mesoporous silica aerogels for sunflower oil refining and investigation of their adsorption performance

AbstractInvolving a succession of oil refining stages for edible oil production, a notable constraint lies in the necessity to employ diverse adsorbents at various steps within these processes. This study investigates the synthesis of mesoporous silica aerogels from rice husk ash, comparing their efficacy in physical sunflower oil refining with earth clay (Bentonite) and commercial silica (Trisyl). Tetraethyl orthosilicate (TEOS) impact during aging was analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and N2 adsorption-desorption analyzer to examine alterations in the structure of silica aerogels. The surface areas of TEOS-doped silica aerogel (TSA) and non-TEOS-doped silica aerogel (NTSA) were 296.18 and 267.06 m²/g. Mesoporous silica aerogels were evaluated for their ability to reduce free fatty acids (FFA), peroxide value (PV), phosphorus, and color pigments in sunflower oil. TSA and NTSA demonstrated significant FFA removal, with TSA at 3 wt.% achieving the highest performance of 32.2%. TSA also effectively reduced PV and phosphorus compared to NTSA, Bentonite and Trisyl, exhibiting performance similar to Bentonite in the bleaching process. TEOS-doped silica aerogels have shown promise as adsorbents for impurity removal in sunflower oil and has emerged as the potential adsorbent that can comprehensively and effectively meet the requirements of many edible oil physical refining applications in a singular step. Graphical Abstract

Visible-light-driven photocatalytic degradation of tetracycline using citric acid and lemon juice-derived carbon quantum dots incorporated TiO2 nanocomposites

Tetracyclines (TC) are consistently found in aquatic ecosystems, contributing to the development and spread of antibiotic resistance genes and antibiotic-resistant bacteria. This poses adverse effects on aquatic organisms and humans, emphasizing the need for an effective approach to remove these contaminants. TiO2-based photocatalysts hold great potential for efficiently removing TC from water. This study aimed to synthesize TiO2 nanocomposites incorporated with carbon quantum dots (CQDs) derived from both artificial and natural sources. The nanocomposites were characterized using X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption test. The incorporation of CQDs into TiO2 resulted in the reduction of the band gap energy from 3.17 eV in pure TiO2 to 3.10 eV, broadening the light absorption range, and improving the charge carrier transfer efficiency. Continuously generated electrons led to the production of reactive oxygen species, predominantly •O2–, contributing to TC degradation. Holes and •OH radicals also played a significant role in TC degradation. As a result, CQDs/TiO2 nanocomposites exhibited 91.5 % TC removal under visible light irradiation (λ ≥ 400 nm) for 120 min at pH 8. The active sites of TC molecules were determined through density functional theory calculations, and the corresponding degradation pathways of TC were proposed using liquid chromatography-mass spectrometry. Furthermore, this study attempted to synthesize CQDs using lemon juice, showcasing the potential of these eco-friendly photocatalysts for TC removal. The visible-light-driven degradation of TC by the natural-source-derived CQDs/TiO2 nanocomposites demonstrated their applicability in water treatment to effectively address current environmental challenges.

Amine-free synthesis of high-silica ZSM-5 assisted with calcined silicalite-1 and ethanol with the investigation of mechanism

Amine-free synthesis of high silica ZSM-5 with high crystallinity and well-defined morphology was challenging. In this work, ZSM-5 with the fed silica-alumina ratio (SAR) of 100 was rapidly synthesized with the assistance of the calcined silicalite-1 seed and ethanol, and their crystal structures, morphology and microporous properties were characterized by XRD, SEM, FT-IR, ICP and N2 adsorption-desorption and so on. Firstly, the crystallization temperature was optimized between 140 and 180 °C at a certain alkalinity and ethanol content, and 160 °C was selected to not only provide high crystallization rate but also ensure the stability of high-silica skeleton. Secondly, the influences of the EtOH/SiO2 ratio, Na2O/SiO2 ratio and crystallization time on the crystallization of high-silica ZSM-5 were investigated at 160 °C. The results showed well-crystalline high-silica ZSM-5 could be synthesized within a wide range of the EtOH/SiO2 ratios (0.5–2.0) and the increase of ethanol content slightly inhibited the growth of ZSM-5 along b-axial of hexagonal prisms due to the preferential adsorption of excess ethanol on the {010} crystal plane and the formation of Si–O–C2H5; high alkalinity was favorable for the preparation of a small-sized and well-crystalline ZSM-5 due to the rapid depolymerization of calcined seed and the contribution of mass nucleation sites; meanwhile, excellent micropore characteristic of high-silica ZSM-5 further proved that the synthetic strategy of seed + ethanol was feasible. Finally, the synergistic action mechanism of calcined seed and ethanol for the synthesis of high-silica ZSM-5 was revealed that silicalite-1 with MFI structure unit combined with Na+(H2O/EtOH) with larger radius were very important for rapidly assembly of a large number of silica species into MFI framework.

Preparation of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts and reaction mechanism of the side-chain alkylation of toluene to styrene

A series of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts with varied CuAl-LDO contents were prepared by growing CuAl-LDH layers on the surface of Al2O3@Fe3O4 magnetic cores, impregnated with Cs and followed by calcination. The as-synthesized catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM(EDS), XPS, NH3-TPD, CO2-TPD, and VSM techniques. The catalytic performance and reusability of the catalysts for the side-chain alkylation of toluene with formaldehyde were evaluated in a micro-high-pressure reactor, and the reaction mechanism was further studied. The results showed that the Al2O3@Fe3O4 magnetic core of the catalyst was about 110 nm, and the CuAl-LDO formed a staggered lamellar structure with a shell thickness of around 30–45 nm. The magnetic catalyst demonstrated excellent catalytic performance and reusability for the side-chain alkylation of toluene with formaldehyde in one-step to styrene. As-synthesized magnetic Cs/CuAl-LDO@Al2O3@Fe3O4 catalyst with CuAl-LDO content of 20 wt% delivered toluene conversion of 7.97% under optimized conditions, while the styrene selectivity and the selectivity of side-chain alkylation were 90.17% and 98.36%, respectively. The reaction mechanism showed that the benzene ring of toluene was stably adsorbed on the Al3+ acid sites of the CuAl-LDO layers. The C–H group of the side-chain of toluene formed carboanions and protons under the action of the Cuδ+–Oδ– base sites. Formaldehyde formed a transition state of adsorbed formaldehyde under the action of Cuδ+ acid sites. Finally, these adsorbed states and intermediate species accomplished the side-chain alkylation of toluene with formaldehyde to styrene in one-step under the synergic action of acid-base sites. The synergistic effects of suitable acid-base sites and lamellar spatial structures in the catalyst were the key to styrene formation with high selectivity.

Preparation of the MoO3- Fe3O4 nanocomposites for deep oxidative desulfurization of model fuel: Optimization and experimental design

In the present study, the catalytic activity of the MoO3-Fe3O4 of molybdenum oxides prepared by the impregnation method was investigated in the extractive oxidative desulfurization (EODS) process. Structural characterization of the nanocomposite catalysts was studied by XRD, N2 adsorption–desorption isotherm, FT-IR, and VSM analyses. The EODS technology was applied to remove sulfur from a model fuel (dibenzothiophene in n-octane, DBT) using H2O2 as the oxidant, acetonitrile as the extracting solvent, and MoO3-Fe3O4 as the catalysts. Among the catalysts with various loadings of MoO3 on Fe3O4 nanoparticles (3, 6, 9, 12, and 15 wt%), the catalyst with 9 wt% MoO3 demonstrated the highest performance. Subsequently, the optimal design of the experiments using response surface methodology (RSM) based on Box-Behnken design (BBD) was applied to study the effects of the independent parameters such as O/S molar ratio, reaction temperature, and catalyst dosage on sulfur removal efficiency. Optimization studies were performed, and maximum sulfur removal efficiency of 98 % was achieved under the optimal conditions of 58 °C, O/S molar ratio: 5.9, and 0.116 g of 9 wt% MoO3-Fe3O4 as catalysts. The activity of the catalyst remained unchanged after six times recycling in the EODS process. Additionally, a catalytic reaction mechanism was proposed.

Physical Characteristic and In-Vitro Bioactivity Property of Sintered Glasses made via Sol-Gel and Powder Sintering Process

In this work, ternary system (SiO2-CaO-P2O5) biocompatible glass with different compositions (CaO/P2O5 ratio) were prepared by sol-gel method and sintering process. The physical characteristic and bioactive properties of each different sample composition were analyzed using XRF, particle sizer, N2 adsorption-desorption, FTIR, XRD, and FESEM-EDX. The sintered glass pellets were subjected to immersion studies in a simulated body fluid (SBF) solution for 14 days. All compositions of gel-glass particulates showed mesoporous-type structures and consisted of very high porosities with nano-pores in size. Different Ca/P ratios in gel-glass composition are affected by different porous characteristics. All compositions of sintered glass showed very good bioactive behavior by significant deposition of the carbonate apatite layer. Sintered glass with the Ca/P ratio = 2.33 showed very significant bioactive properties as it also comprised the highest pore volume and size. However, sintered glass with the lowest Ca/P ratio (Ca:P=1.50) showed a quite significant reduction in the bioactive property as it also consisted of the lowest pore volume and pore sizes. Hence, the in-vitro bioactivity property of sintered glass is significantly influenced by the increase in its porous characteristics due to differences in the Ca/P ratio.

Ni decorated three-dimension hierarchical pyramidal ZrO2–Al2O3 nanoporous sheets for methane production

ZrO2–Al2O3 nanocomposites were synthesized by a modified co-precipitation method and loaded with 5%Ni as catalysts for methane production via n-heptane cracking. The as-synthesized nanocomposites were characterized by several techniques such as XRD, N2 adsorption-desorption, XPS, TEM, SEM, AFM, TGA, DTG, NH3 -TPD and Raman analysis. The XRD results confirmed the synthesis of amorphous γ alumina and hexagonal phase of zirconium alumina oxide (Zr5Al3O0.5) solid solution. XRD and SEM analyses showed additional small size Related to monoclinic phase of ZrO2 particles loaded on the Al2O3 surface. BET analyses confirmed the ZrO2–Al2O3 formation in mesoporous sheets structure. TEM images of the neat alumina, 10 ZA and their corresponding Ni loaded samples (Ni@10 ZA) revealed well-defined 3D hierarchical pyramidal structures with a height about 200 nm. All catalysts under this study exhibited high tendency to favor methane production via n-heptane cracking. At higher reaction temperatures, Ni@10 ZA catalyst exhibited higher cracking activity compared to the other prepared catalysts under this investigation which confirmed by NH3 -TPD analysis. A promising yield of methane was achieved at about 88 % coupled with 94.71 % selectivity at reaction temperature of 400 °C. Herein, the data collected through this research work revealed that Ni@10 ZA is a promising candidate for methane production via n-heptane cracking.