High Brunauer Emmett Teller Surface Area Research Articles

Microporous Carbon and Carbon/Metal Composite Materials Derived from Bio-Benzoxazine-Linked Precursor for CO2 Capture and Energy Storage Applications.

There is currently a pursuit of synthetic approaches for designing porous carbon materials with selective CO2 capture and/or excellent energy storage performance that significantly impacts the environment and the sustainable development of circular economy. In this study we prepared a new bio-based benzoxazine (AP-BZ) in high yield through Mannich condensation of apigenin, a naturally occurring phenol, with 4-bromoaniline and paraformaldehyde. We then prepared a PA-BZ porous organic polymer (POP) through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) in the presence of Pd(PPh3)4. In situ Fourier transform infrared spectroscopy and differential scanning calorimetry revealed details of the thermal polymerization of the oxazine rings in the AP-BZ monomer and in the PA-BZ POP. Next, we prepared a microporous carbon/metal composite (PCMC) in three steps: Sonogashira coupling of AP-BZ with P-T in the presence of a zeolitic imidazolate framework (ZIF-67) as a directing hard template, affording a PA-BZ POP/ZIF-67 composite; etching in acetic acid; and pyrolysis of the resulting PA-BZ POP/metal composite at 500 °C. Powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller (BET) measurements revealed the properties of the as-prepared PCMC. The PCMC material exhibited outstanding thermal stability (Td10 = 660 °C and char yield = 75 wt%), a high BET surface area (1110 m2 g–1), high CO2 adsorption (5.40 mmol g–1 at 273 K), excellent capacitance (735 F g–1), and a capacitance retention of up to 95% after 2000 galvanostatic charge–discharge (GCD) cycles; these characteristics were excellent when compared with those of the corresponding microporous carbon (MPC) prepared through pyrolysis of the PA-BZ POP precursors with a ZIF-67 template at 500 °C.

Biosynthesis of Tithonia diversifolia leaf mediated Zinc Oxide Nanoparticles loaded with flamboyant pods (Delonix regia) for the treatment of Methylene Blue Wastewater

The large capacity of wastewater production due to rapid growth of industries has resulted in limited water resources. The need to protect and conserved water resources have enforced researchers worldwide to focus on the development of an effective, economical and environmentally friendly novel materials. In this study, green synthesis of zinc oxide nanoparticles (ZnONPs) using T. diversifolia leaf extract by hydrothermal method was loaded on the surface of flamboyant pods (Delonix regia) activated carbon (FPAC). The developed ZnONPs loaded on the surface flamboyant pods activated carbon (ZnONPs-FPAC) was used successfully to remove of methylene blue (MB) from aqueous solution. The developed FPAC, ZnONPs and ZnONPs-FPAC were characterized UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) techniques. The antibacterial activity of the synthesized FPAC, ZnONPs and ZnONPs-FPAC were screened and the results revealed that ZnONPs has an excellent antibacterial activity when compared. Batch adsorption studies were conducted to investigate the influence of process parameters such as initial concentration, contact time, pH, adsorbent dosage and temperature on MB uptake. The high BET surface area of 794.48 m2/g and mesoporous ZnONPS-FPAC developed gave good adsorption capacity of 186 mg/g. Equilibrium adsorption data of MB were modelled using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherm model. The adsorption of MB onto ZnONPs-FPAC was best described by Freundlich model indicating surface heterogeneity, and pseudo-second-order kinetics according to %Δqe (normalized standard deviation), SSE (sum of square error), and R2 (coefficient of determination) values. The results of the thermodynamic suggest that the adsorption process of MB onto ZnONPs-FPAC is endotherm, favourable, spontaneous, and physical. In nature. The reusability of ZnONPs-FPAC was examined upto five cycles with no significant loss in removal efficiency. The mean free energy (E), and Enthalpy (ΔH) values calculated, suggested that the adsorption mechanism of MB on ZnONPs-FPAC is dominated by physical adsorption.

Incorporation of Fe in mixed CoCu-alkoxide hollow sphere for enhancing the electrochemical water oxidation performance

The promotion of water electrolysis performance heavily relies on the development of affordable and efficient electrocatalytic materials for the oxygen evolution reaction (OER). In this study, ternary Fe-substituted CoCu-glycerate microspheres (CoCuFe(X)-Gly) with cobalt (Co):copper (Cu):iron (Fe) atomic ratio of 2:1-X:X (X = 0.15, 0.3, 0.5, 0.8) have been prepared through facile template-free solvothermal method to examine their performance as alkaline OER catalyst. The results suggested that Fe incorporation could enhance the OER activity, and all Fe-modified samples showed lower overpotential with faster kinetic, as revealed by their Tafel slope and electrochemical impedance spectroscopy (EIS) analysis. Among the fabricated samples, CoCuFe(0.5)-Gly possessed the smallest overpotential of 317 mV at 10 mA/cm2 with 3.58-fold higher current density than that of Fe-free CoCu-Gly at the overpotential of 350 mV. Cyclic voltammetry (CV) disclosed that Fe incorporation imposed strong electronic interactions that facilitate the transformation of metal-glycerate surface into active oxyhydroxide species under anodic condition prevalent before oxygen evolution reaction. Using various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) method of surface area analysis, and thermogravimetric analysis (TGA), the physiochemical traits of samples have been carefully elucidated to determine the changes applied upon Fe substitution. Also, through Fe introduction, owing to the outward diffusion of ions to replace 2-propanol with glycerol, the solid microspheres partly become hollow which results in higher BET surface area and increase in accessible active sites. However, the evaluation of current density normalized by electrochemical active surface area (ECSA) indicates that the promotional effect of Fe was not solely related to the higher surface area but also because the intrinsic activity of Fe-modified samples has also been enhanced. The durability of optimal CoCuFe(0.5)-Gly catalyst has been examined using chronopotentiometry, chronoamperometry and potential cycling methods the findings of which suggest the good short-term and long-term stability of catalyst.

Imparting Superhydrophobicity to Porphyrinic Coordination Frameworks Using Organotin

Imparting Superhydrophobicity to Porphyrinic Coordination Frameworks Using Organotin

Preparation and characterization of activated carbon from hydrochar by hydrothermal carbonization of chickpea stem: an application in methylene blue removal by RSM optimization

Herein, mesoporous activated carbon (AC) was prepared through potassium hydroxide (KOH) activation of hydrochar derived from the hydrothermal carbonization (HTC) of chickpea stem (CS), and successfully applied to remove methylene blue (MB) dye from aqueous solutions in a batch system. The HTC-CSAC was prepared depending on different impregnation ratios (hydrochar:KOH, 50–150%), impregnation times (12–48 h), activation temperatures (400–600) and activation times (30–60 min). To define HTC-CSAC, various analytical techniques such as iodine adsorption number (IAN), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) were used. In the removal process of MB by the best HTC-CSAC with a high IAN of 887 mg g−1 obtained under conditions including impregnation ratio of 70%, activation time of 45 min, activation temperature of 600 and impregnation time of 24 h, the effects of adsorption parameters such as pH factor (2–10), adsorbent dosage (50–100 mg), initial MB concentration (40–80 mg/L) and contact time (90–180 min) were studied. Besides, a detailed evaluation of the adsorption mechanism for the removal of MB by HTC-CSAC was performed. The Langmuir model indicated the best isotherm data correlation, with a maximum monolayer adsorption capacity (Qmax ) of 96.15 mg g−1. The adsorption isotherm findings demonstrated that the MB removal process is feasible, and that this process takes place through the physical interaction mechanism. Additionally, the HTC-CSAC adsorbent exhibited a high regeneration and reuse performance in MB removal. After five consecutive adsorption-desorption cycles, HTC-CSAC maintained the reuse efficiency of 77.86%. As a result, the prepared HTC-CSAC with a high BET surface area of 455 m2 g−1 and an average pore diameter of 105 Å could be recommended as a promising and reusable adsorbent in the treatment of synthetic dyes in wastewaters.

Gelatin‐pyrolyzed mesoporous N‐doped carbon supported Pd as high‐performance catalysts for aqueous Heck reactions

Nitrogen‐doped mesoporous carbon‐supported Pd (Pd@N‐C) catalysts were prepared by pyrolyzing gelatin/templates/PdCl2 hydrogels under N2 atmosphere at 800°C. Using poly (ethylene glycol) block poly (propylene glycol) block poly (ethylene glycol) (P123) as soft template and/or colloidal SiO2 as hard templates can significantly improve the Brunauer‐Emmett‐Teller (BET) surface area, porous structure, and pore volumes of the resultant Pd@N‐C catalysts. Pd nanoparticles sized from 10–20 nm can be well immobilized on the mesoporous carbon matrix by one‐pot carbonization (OC) and/or solution impregnation (SI) process. The resultant Pd@N‐C catalysts with best physical properties was found in the case of Pd@N‐C‐SiO2‐OC (1/1), exhibiting high BET surface area of 695.2 m2/g, large pore volume of 1.05 cm3/g, high mesoporous centered at 3.7 and 9.1 nm, rich N content of 7.7%, and high thermal stability with beginning decomposition temperature above 500°C. It showed excellent activities for aqueous Heck coupling reactions of aromatic iodides and butyl acrylates and can be recycled for at least eight times with yield still higher than 80%. This work might facilitate a versatile platform for green and functional utilization of nature‐rich biopolymer of gelatin.

A Tröger's Base-Derived Covalent Organic Polymer Containing Carbazole Units as a High-Performance Supercapacitor.

Porous organic polymers have been received considerable attention due to their heteroatom-containing structures and high surface areas, which can offer high electrochemical performance in energy applications. The majority of reported Tröger’s base-functionalized porous organic polymers have been applied as effective candidates for sensing and gas separation/adsorption, while their use as electrode materials in supercapacitors is rare. Here, a novel covalent microporous organic polymer containing carbazole and Tröger’s base CzT-CMOP has been successfully synthesized through the one-pot polycondensation of 9-(4-aminophenyl)-carbazole-3,6-diamine (Cz-3NH2) with dimethoxymethane. The polycondensation reaction’s regioselectivity was studied using spectroscopic analyses and electronic structure calculations that confirmed the polycondensation occurred through the second and seventh positions of the carbazole unit rather than the fourth and fifth positions confirmed by first-principles calculations. Our CzT-CMOP exhibited high thermal stability of approximately 463.5 °C and a relatively high Brunauer–Emmett–Teller surface area of 615 m2 g−1 with a nonlocal density functional theory’s pore size and volume of 0.48 cm3 g−1 and 1.66 nm, respectively. In addition, the synthesized CzT-CMOP displayed redox activity due to the existence of a redox-active carbazole in the polymer skeleton. CzT-CMOP revealed high electrochemical performance when used as active-electrode material in a three-electrode supercapacitor with an aqueous electrolyte of 6 M KOH, and it showed specific capacitance of 240 F g−1 at a current density of 0.5 A g−1 with excellent stability after 2000 cycles of 97% capacitance retention. Accordingly, such porous organic polymer appears to have a variety of uses in energy-related applications.

Synthesis of self-assembled hierarchical AlPO-34 microspheres by using an ionic liquid and its application in heavy metal removal.

Hierarchical AlPO-34 molecular sieves microspheres were synthesized in a [BMIm]Br ionic liquid without template or complex post-treatment process. The formation mechanism of such framework structures and their morphology were investigated. [BMIm]Br was proven to serve as both solvent and sole provider of the structure directing agent. The organic amine in the compound affects the framework density of the crystals and promotes the formation of a chabazite (CHA) type framework. After ageing for 1 h the AlPO-34 microspheres are formed due to the aggregation properties of the ionic liquid. The hierarchical mirosphere has a relatively high Brunauer–Emmett–Teller surface area and a considerably uniform mesoporous channel network. The hierarchical AlPO-34 microspheres were used as absorbers of heavy metal cations and showed a higher loading capacity and distribution coefficient compared with the AlPO-34-NH.

Highly Efficient Heterogeneous Pd@POPs Catalyst for the N-Formylation of Amine and CO2

Utilization of CO2 for the production of fine chemicals has become a research hotspot for a long time. In order to make use of CO2, we developed a highly efficient heterogeneous catalyst (denoted as Pd@POPs) for the N-formylation reaction of amine and CO2 under mild conditions. The Pd catalyst was based on a porous organic polymer derived from the solvothermal polymerization of vinyl-functionalized PPh3. A series of characterizations and comparative experiments demonstrated that the Pd@POPs catalyst has high BET (Brunauer-Emmett-Teller) surface areas, hierarchical pore structure, and uniform dispersion of Pd active sites resulting from the formation of strong coordination bonds between Pd species and P atoms in the porous organic polymer (POP) support. In addition to the excellent activity, the Pd@POPs catalyst shows good stability for the N-formylation reaction of amine and CO2.

Preparation of Vanillic Acid-Loaded Core-Shell Gold Nanospheres/Mesoporous Silica Nanoparticles for the Treatment of Orthopedic Infection.

Orthopedic infection is a serious complication in surgeries and remains a great challenge in clinics. Here, the natural antimicrobial compound vanillic acid-loaded gold nanospheres/mesoporous silica nanoparticles (VA@Au-MSNs) were fabricated for chemo-photothermal synergistic therapy to orthopedic infections. The shape and morphology of Au-MSN and VA@Au-MSN were observed by scanning electron microscopy and transmission electron microscopy. The properties of VA@Au-MSN or related components were characterized by dynamic light scattering, thermogravimetric analysis, Brunauer–Emmett–Teller (BET) analysis, and photothermal analysis. Vanillic acid released from VA@Au-MSN was detected in phosphate-buffered saline. A cytotoxicity test and an antibacterial assessment were performed to explore the biosafety and antibacterial activity of VA@Au-MSN, respectively. The results showed that Au-MSN possessed a high BET surface area (458 m2/g). After loading vanillic acid, the BET surface area reduced to 72 m2/g. The loading efficiency of Au-MSN was 18.56%. Under 808 nm laser irradiation, the temperature at the wound site injected with the Au-MSN solution in the mouse increased from 24 to 60 °C within about 12 s. Also, the high temperature could promote the release of vanillic acid from VA@Au-MSN. Additionally, VA@Au-MSN has no obvious cytotoxicity to MC3T3-E1 cells, but the generated local hyperthermia and the VA released from VA@Au-MSN had excellent antibacterial activity against Staphylococcus aureus in a synergistic way. In conclusion, the VA@Au-MSN with biosafety and excellent antibacterial performance might be applied for the treatment of orthopedic infection.

Core and dopant effects toward hydrogen gas sensing activity using Pd@N-CeO2 core–shell nanoflatforms

Developing efficient and stable hydrogen gas sensors may be of urgent demand for its safety uses. Herein, Pd@N-CeO2 core–shell nanoflatforms (CSNFs) are fabricated and utilized for this purpose. The resulting Pd@N-CeO2 CSNFs offer small particle sizes with high Brunauer–Emmett–Teller (BET) surface area and porous nanostructures. The core–shell sensors establish high hydrogen sensing response and fast response and recovery times at a lower optimal working temperature compared to undoped and doped CeO2 ones. In addition, it further demonstrates high selectivity and stability toward hydrogen gas among interfering different target gases. The hydrogen gas sensing betterment is synergistically assigned to Pd core, N dopant, and high BET surface area effects, which decidedly modulate the electrical resistance of core–shell sensors to improve overall gas sensing performance accordingly. Our finding provides an efficient way to design and fabricate versatile hydrogen gas sensors based on metal@nitrogen doped-semiconductor oxide core–shell nanostructures.

Surface engineering of intrinsically microporous poly(ether-ether-ketone) membranes: From flat to honeycomb structures

Surface engineering of polymeric membranes can induce subtle changes in membrane properties and enhance their performance. Numerous membrane surface modification methods have been developed to improve the material performance. However, these methods can be complex, thus limiting their practical applications. Herein, we present a simple method for fabricating membranes with honeycomb surfaces by controlling the polymer molecular weight (Mw). Spirobisindane-based intrinsically microporous poly(ether-ether-ketone) (iPEEK-SBI) homopolymers with low and high Mws were synthesized and used to prepare organic solvent nanofiltration (OSN) membranes. The significant effects of polymer Mw on its physical properties, membrane morphology, and OSN performance were systematically investigated. iPEEK showed excellent solution processability, high Brunauer–Emmett–Teller surface area, and remarkable thermal stability. Three mechanically flexible OSN membranes exhibiting honeycomb surfaces with different honeycomb cell sizes were prepared using iPEEK-SBI homopolymers with low Mws at concentrations of 27–39 wt% in N-methyl-2-pyrrolidone. By contrast, the use of iPEEK-SBI homopolymers with high Mws yielded membranes with flat surfaces. The Mw cutoffs of the membranes were fine-tuned in the range of 408–772 g mol−1 by adjusting the dope solution concentration. Although the Mw cutoffs were unaffected by polymer Mw, the membranes derived from the polymer with low Mw exhibited substantially higher solvent permeance (18%–26%) than that of the high Mw membrane prepared at the same dope solution concentration. Stable performance was demonstrated over seven days of continuous cross-flow filtration and a six-month aging of the membranes. This work shows the importance of surface engineering for OSN membranes by adjusting polymer Mw. These findings open a new avenue for fine-tuning the properties of OSN membranes.

Microwave Solvothermal Synthesis of Three-Dimensional Bi2MoO6 Microspheres with Enhanced Photocatalytic Activity.

In this study, three-dimensional (3D) Bi2MoO6 microspheres were successfully fabricated by a facile, rapid, and mild microwave solvothermal strategy for the first time. The resultant 3D Bi2MoO6 microspheres exhibited superior adsorption capacity and photocatalytic efficiency in the degradation of the representative antibiotic ciprofloxacin under visible light, for which the reaction kinetic rate constant is 7.5 times as high as that of the as-synthesized zero-dimensional Bi2MoO6 nanoparticles. The 3D hierarchical porous structure and the high Brunauer–Emmett–Teller surface area providing abundant reactive sites mainly contributed to the enhanced photocatalytic activity. The results highlight the feasibility of 3D Bi2MoO6 microspheres as an efficient visible-light-responsive photocatalyst for antibiotic removal in an aqueous system.

Correlations Between Alkali and Crystallinity in lyocell-Based ACF Probed with X-Ray Diffraction

This study examined the effect of alkalis on lyocell-based activated carbon fibres (ACFs) with high Brunauer-Emmett-Teller (BET) surface areas, using X-ray diffraction (XRD). Here, alkali treatments were conducted using 10 ~ 25 % NaOH and KOH on lyocell samples for 3 h at ambient room temperature. A secondary treatment with 4 % each of KOH and H3PO4 for an additional 3 h followed. An activated form of the samples was prepared by oxidation (stabilisation), carbonisation, and activation. The final ACF form of the samples showed a porous structure with high BET surface areas (> 1,000 m<sup>2</sup> g<sup>-1</sup>). A 25 % dosage of NaOH produced the highest BET surface area compared to other samples. In terms of crystallinity, a 15 % dosage of KOH was found to be the optimum dosage to secure the highest degree of crystallinity among all samples. Meanwhile, the NaOH was successfully shifted the samples into the most distinct form of cellulose II. 15 % NaOH was found to secure the most stable thermal characteristics, as determined via thermo-gravimetric analysis. The present work demonstrates the various physio-chemistries of ACFs prepared with different proportions and types of alkalis, leading to intriguing potential applications.

Study on the preparation and mechanism of chitosan-based nano-mesoporous carbons by hydrothermal method

In this paper, the hydrothermal method to synthesize and characterize nano-mesoporous carbons and their synthesis mechanism are reported. Using tri-block Pluronic F127 as a structuring agent and chitosan (CS) as a carbon source, the nano-mesoporous carbons were synthesized by a one-step sol polymerization and hydrothermal process, followed by carbonization at high temperature. The pore structure of the carbon materials was characterized by physical adsorption analyzer, and the morphology was characterized by SEM and TEM. Fourier-transform infrared, Raman and x-ray photoelectron spectroscopy were used to study the synthesis mechanism. The results showed that the self-assembly polymerization reaction between CS and F127 in a weakly acidic system was only implemented driven by the hydrogen bond auxiliary electrostatic interactions initiated by protonated amino groups. The nitrogen from amino groups and acetylamino groups, the oxygen in acetylamino groups, hydroxyl groups and the glycosidic bonds of CS, and the oxygen from the hydrophilic segments of F127 were the main active sites. The mesoporous material possesses a high Brunauer–Emmett–Teller surface area (163 m2/g) and large pore volume (0.462 cm3/g) with pore diameter around 2.1 nm. The nitrogen content was 1.08% and existed in the pore wall as the form of pyridine, pyrrole and quaternary nitrogen.

Synthesis of carbazole-based polymer derived N-enriched porous carbon for dyes sorption

A (N-vinyl carbazole)-based polymer, namely PPVK, was subsequently synthesized by free radical polymerization and oxidative polymerization. This material exhibits permanent porosity, good physicochemical stability, and plenty of nitrogen units. All these features make PPVK promising precursor for constructing N-enriched porous carbon. Using KOH as the activating agent, porous carbon material was prepared and its adsorption performance was also evaluated. Due to the high Brunauer–Emmett–Teller surface area (1832 m2 g−1) and abundant nitrogen atoms, the porous carbon, CPVK-800, displays adsorption capacity of 1074 mg g−1 for Rhodamine B, which is far higher than that reported for commercial activated carbon (0.36 mmol g−1). Kinetic investigations indicate that the adsorption behaviour follows the Langmuir isotherm model and pseudo-second-order kinetics. Besides the cationic dye rhodamine B, CPVK-800 also can be used to adsorption removal of anionic dye methyl orange, with uptake of 739 mg g−1. Findings in this study highlight the potential of using carbonaceous polymer as an effective adsorbent for organic dyes.

Dual‐Function Fluorescent Covalent Organic Frameworks: HCl Sensing and Photocatalytic H2 Evolution from Water

AbstractTwo ultrastable luminescent covalent organic frameworks (COFs), PyTA‐BC and PyTA‐BC‐Ph, are synthesized through polycondensations of 4,4′,4″,4′″‐pyrene‐1,3,6,8‐tetrayl)tetraaniline (PyTA‐4NH2) with two carbazole‐based derivatives having different degrees of conjugation. The PyTA‐BC and PyTA‐BC‐Ph COFs exhibit ultrahigh thermal stabilities (up to 421 °C), excellent crystallinity, and high Brunauer–Emmett–Teller surface areas (up to 1445 m2 g−1). These COFs display strong fluorescence emissions in various solvents, with their emission maxima gradually red‐shifting upon increasing the polarity of the solvent (solvatochromism). Upon exposure to HCl, they respond very rapidly and sensitively in terms of changing their colors and fluorescence emission maxima. In the presence of a sacrificial electron donor, these COFs mediate the highly efficient photocatalytic evolution of H2 from water. In the absence of a noble metal cocatalyst, the COFs and ascorbic acid provide a photocatalytic H2 production of up to 1183 µmol g−1 h−1 (λ ≥ 420 nm); this value is the highest reported to date for a COF. Such COFs appear to be potentially useful as chemosensors for the naked‐eye and sensitive spectroscopic detection of HCl and as cocatalysts for the sustainable photocatalytic production of H2 from water.

Optimization Aging Parameters of Mg Silica Aerogel Using Box-Behnken Approach

The main objective of the present study was to investigate the application of Box–Behnken design which is a type of optimization design of response surface methodology (RSM) to predict and optimize some aging condition of magnesium silica aerogel (MSA) for improving surface properties such as surface area, pore volume and pore size. Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) techniques, tap density method and helium pycnometer were used to characterize aerogels. The operating conditions were optimized as a function of the molar ratio of Mg:Si (0.35, 0.50 and 0.65), aging time (24 h, 60 h and 96 h) and aging temperature (50 oC, 70 oC and 90 oC). Lack of fit test indicates that the quadratic regression model was significant with the high coefficients of determination values for all three properties. Optimized aging factors for synthesis MSA with high BET surface area, high BJH pore volume and average BJH pore size were found to be 0.5 Mg:Si molar ratio, 79.62 oC and 61.51 h, respectively. Under these conditions, magnesium silica aerogels have great properties: 734 m2.g-1 BET surface area, 0.41 cm3.g-1 BJH pore volume and 4.91 nm BJH pore size, 0.12 g.cm−3 density and 95 % porosity. Box-Behnken is useful optimization tool for production of nanoporous magnesium silica aerogel.

PREPARATION of Gd2O3 NANOMATERIALS via SOLUTION COMBUSTION SYNTHESIS FOR OXIDATIVE COUPLING OF METHANE

In this study, in the production of Gd2O3 material which has many usage areas, solution combustion synthesis was used and the changes in the physical and structural properties of the material were investigated by changing the oxidant/fuel ratio. The resulting metal oxide powders were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Thermogravimetric-Differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM) analysis and tested in oxidative coupling of methane. Cubic and monoclinic phases were observed in Gd2O3 crystal structure at fuel-rich and stoichiometric conditions, and only cubic phase was determined at fuel-lean conditions. It was determined that the obtained powders were mesoporous and the highest BET surface area was obtained at stoichiometric oxidant/fuel ratio (18.6 m2/g). It was determined that the powders were formed from rather small particles (<30 nm) and with layered or stacked structure. The catalytic performance of Gd2O3 nanoparticles was found to be dependent on the BET surface area and crystal structure. The highest C2 yield was obtained at 720°C with Gd2O3-0.5 (8.5%).

Effective Approach toward Conjugated Porous Organic Frameworks Based on Phenanthrene Building Blocks: Metal-Free Heterogeneous Photocatalysts.

This paper reports a simple approach for the preparation of new photo-active conjugated porous polymers (CPPs) based on phenanthrene building blocks with a high Brunauer-Emmett-Teller (BET) surface area. Starting from 2,7-diiodophenanthrene-9,10-dione and its bis-dioxolane derivative with different alkynyl comonomers, we prepared a series of CPPs by C-C Sonogashira-Hagihara coupling activated by microwaves. Moreover, we demonstrated that these functionalized CPPs after hydrolysis to the corresponding diketones show much higher BET surface areas than those obtained directly from the phenanthrene-9,10-dione monomer. Reaction of diketone-hydrolyzed polymers with 2,4-difluoro-6-hydroxybenzaldehyde yields phenantroimidazole derivatives. Indeed, these structurally robust polymers result in efficient, recyclable, heterogeneous photo-organocatalysts for the aza-Henry reaction (C-H functionalization) induced by visible-light irradiation.