High BET Surface Area Research Articles

Remarkable Structural Diversity between Zr/Hf and Rare-Earth MOFs via Ligand Functionalization and the Discovery of Unique (4, 8)-c and (4, 12)-connected Frameworks.

Ligand modification in MOFs provides great opportunities not only for the development of functional materials with new or enhanced properties but also for the discovery of novel structures. We report here that a sulfone-functionalized tetrahedral carboxylate-based ligand is capable of directing the formation of new and fascinating MOFs when combined with Zr4+/Hf4+ and rare-earth metal cations (RE) with improved gas-sorption properties. In particular, the resulting M-flu-SO2 (M: Zr, Hf) materials display a new type of the augmented flu-a net, which is different as compared to the flu-a framework formed by the nonfunctionalized tetrahedral ligand. In terms of properties, a remarkable increase in the CO2 uptake is observed that reaches 76.6% and 61.6% at 273 and 298 K and 1 bar, respectively. When combined with REs, the sulfone-modified linker affords novel MOFs, RE-hpt-MOF-1 (RE: Y3+, Ho3+, Er3+), which displays a fascinating (4, 12)-coordinated hpt net, based on nonanuclear [RE9(μ3-Ο)2(μ3-ΟΗ)12(-COO)12] clusters that serve as hexagonal prismatic building blocks. In the absence of the sulfone groups, we discovered that the tetrahedral linker directs the formation of new RE-MOFs, RE-ken-MOF-1 (RE: Y3+, Ho3+, Er3+, Yb3+), that display an unprecedented (4, 8)-coordinated ken net based on nonanuclear RE9-clusters, to serve as bicapped trigonal prismatic building units. Successful activation of the representative member Y-ken-MOF-1 reveals a high BET surface area and total pore volume reaching 2621 m2 g-1 and 0.95 cm3 g-1, respectively. These values are the highest among all RE MOFs based on nonanuclear clusters and some of the highest in the entire RE family of MOFs. The present work uncovers a unique structural diversity existing between Zr/Hf and RE-based MOFs that demonstrates the crucial role of linker design. In addition, the discovery of the new RE-hpt-MOF-1 and RE-ken-MOF-1 families of MOFs highlights the great opportunities existing in RE-MOFs in terms of structural diversity that could lead to novel materials with new properties.

Ceramic membrane-based ultrafiltration combined with adsorption by waste derived biochar for textile effluent treatment and management of spent biochar.

Effluents produced in the textile industries are important sources of water pollution due to the presence of toxic dyes, auxiliary chemicals, organic substances etc. Recycling of such industrial wastewater is one major aspect of sustainable water management; hence present study is focused on an eco-friendly process development for reclamation of higher loading textile wastewater. Industrial effluent samples with varying loading were collected from textile processing units located in and around Kolkata city. Vegetable waste collected from local market was utilized to prepare an efficient biochar for elimination of the recalcitrant dyes. Prior to adsorption, ceramic ultrafiltration (UF) process was used for reduction of the organic loading and other suspended and dissolved components. A remarkably high BET surface area of 1216 m2g-1 and enhanced pore volume of 1.139 cm3g-1 was observed for biochar. The maximum adsorption capacity obtained from the Langmuir isotherm was about 300mg.g-1. The combined process facilitated >99% removal of dyes and 77-80% removal of chemical oxygen demand (COD) from the various samples of effluent. The treated effluent was found suitable to discharge or reuse in other purposes. About 95% of dye recovery was achieved during biochar regeneration with acetone solution. The dye loaded spent biochar was composted with dry leaves and garden soil as bulking agent. Prepared compost could achieve the recommended parameters with high nutritional value after 45days. The overall study showed potential of the proposed process towards treatment of toxic dye loaded textile effluent in an environment friendly and sustainable approach.

Graphitic porous carbon with multiple structural merits for high-performance organic supercapacitor

To circumvent the trade-off contradiction between porosity and graphitization of carbon materials for high-performance electrical double layer supercapacitors (EDLCs), we herein demonstrate a facile and effective solution by simultaneously achieving the etching reaction and graphitization process of a coal precursor with high carbon content and pre-formed graphite-like crystallites. The resulting graphitic porous carbon (AC-1000) exhibits simultaneously a high BET surface area up to 3214 m2 g−1 and a long-range graphitic network. In addition, AC-1000 also possesses a high packing density, low heteroatom and metal impurity contents (oxygen content less than 3.5 at.% and metal impurity less than 200 ppm) as well as an unprecedented production yield of 40%, all of which are highly desirable, but rarely achieved in reported porous carbons. The constructed organic supercapacitor delivers all-round improvements in capacitive performances in term of high capacitances (172 F g−1 at 0.5 A g−1 and 150 F g−1 at 30 A g−1), high energy density (37.2 Wh kg−1 at 303 W kg−1) and high power density (20.5 kW kg−1 at 25.3 Wh kg−1) as well as an excellent cycling stability of 10,000 cycles, markedly surpassing commercial activated carbon and showing application potential for commercial organic EDLCs.

One-step in-situ synthesis of porous Fe3+-doped TiO2 octahedra toward visible-light photocatalytic conversion of CO2 into solar fuel

Here, hollow Fe3+ doped TiO2 (Fe–TiO2) octahedra were obtained via one-step hydrothermal method with MIL-101(Fe) as the template as well as the iron ion source. By introducing Ti precursor onto MIL-101(Fe) followed by HF etching and hydrothermal treatment, Fe-doped TiO2 with high porosity and hollow structure was obtained. The as-synthesized Fe–TiO2 octahedra consist of numerous small nanoparticles with particle sizes between 10 and 20 nm and possess a high specific surface area of 275 m2 g−1 together with uniform mesopores of 3.7 nm in pore diameter. After heat treatment in air at 500 °C (named Fe–TiO2-500), the BET surface area and the mesopore size of the sample were changed to 202 m2 g−1 and 3.9 nm, respectively. Compared to other Fe-doping methods, this method reported here favors better and more uniform Fe doping into the TiO2 lattice and improves the porosity and specific surface area. As a result of the Fe doping, the bandgaps of Fe–TiO2 and Fe–TiO2-500 were about 2.75 eV and 2.42 eV, respectively. Fe–TiO2-500 shows excellent photocatalytic activity due to its special structure, high BET surface area and porosity. The yield of CH4 is about 7.73 μmol g−1 after loading of Pt within 12 h of reaction time under visible light illumination (λ > 420 nm).

Highly permeable polyimides incorporating Tröger's base (TB) units for gas separation membranes

Two novel polyimides incorporating Tröger's Base (TB) units, Bio-PITB-1 and Bio-PITB-2, were facilely synthesized from lignin-based imide-containing diamines via TB polymerization. The polymers exhibited excellent thermal stability, finely tuned microporous structures with high BET surface areas (~569 m2 g−1), high fractional free volumes (~0.224), and appropriate inter-chain distances (~0.68 and ~0.38 nm). Mechanically tough Bio-PITB membranes were successfully achieved due to their high molecular weights (~1.24 × 105 g mol−1) and good solubility in organic solvents. Bio-PITBs presented superior gas transport properties with improved gas permeability compared to the previously reported PI-TBs as well as Bio-TBPIs prepared from the same lignin-based dianhydrides but different synthetic routes. As a result, Bio-PITBs located near the 2008 upper bounds in H2/CH4, H2/N2, and CO2/CH4 gas pairs with H2 and CO2 permeabilities over 1000 Barrer. Furthermore, the effects of membrane drying protocols and physical aging on gas transport behaviors of Bio-PITBs were investigated.

PAA@ZIF-8 incorporated nanofibrous membrane for high-efficiency PM2.5 capture

With growing concerns over air quality in many countries around the world, metal–organic frameworks are now being widely researched for its application in developing air filtration technology for PM2.5 removal. Our study reports the successful fabrication of a polyacrylic acid @zeolitic imidazolate framework-8 (PAA@ZIF-8) membrane using electrospinning technology which shows great promise for PM2.5 filtration. Our PAA@ZIF-8 membrane had a small pore size at 0.5 µm with a porosity of 89.4%, and after modification by ZIF-8, the PAA@ZIF-8 membrane gained porous rough nanofibers, positive surface zeta potential, and high tensile strength. Our tests confirmed the PAA@ZIF-8 membrane’s high potential for PM2.5 filtration over commercial PVDF and electrospun PAA membranes, recording a PM2.5 retention rate of 99.6%. Besides its small pore size, the PAA@ZIF-8 membrane’s rough and porous nanofiber structure created a high BET surface area (344.9 m2/g) which physically adsorbs the PM2.5 particles. Additionally, we found that the positive surface zeta potential (67.3 mV at PH = 7) of the ZIF-8-coated nanofibers attracts negatively charged PM2.5 particles combined in air moisture, thereby further improving the PM2.5 filtration rate.

Ru/P-Containing Porous Biochar-Efficiently Catalyzed Cascade Conversion of Cellulose to Sorbitol in Water under Medium-Pressure H2 Atmosphere

Abstract This paper discloses a simple and productive strategy for the preparation of biochar-based bifunctional catalysts. In this strategy, very cheap bamboo powder is thermally carbonized to yield P-containing porous biochars (PBCs) by the activation of concentrated phosphoric acid (H3PO4), and the latter can be transformed into the target catalysts via loading Ru nanometer particles (NPs) on them (marked as Ru/PBCs). A series of characterizations and measurements support that PBCs have stable and rich micro-meso pores and small strong acidic protons (0.10–0.28 mmol·g−1) attributable to the grafted and/or skeleton phosphorus groups, as well as a strong affinity to β-1,4-glycosidic bonds, thus exhibiting a good acid catalytic activity for the hydrolysis of cellulose to glucose. More importantly, they are excellent acidic supports for the loading of Ru NPs owing to high BET surface area, which can give the loaded Ru NPs uniform and narrow distribution (1–6 nm). The resulting bifunctional Ru/PBCs catalysts possess excellent hydrolytic hydrogenating activity for the one-pot cascade conversion of cellulose and the optimized conditions can achieve ca. 89% hexitol yield with 98% sorbitol selectivity under relatively mild conditions. This work provides a good example for the preparation of biomass-derived bifunctional catalysts and their applications in biorefinery.

A three-dimensional covalent organic framework with turn-on luminescence for molecular decoding of volatile organic compounds

A rare example of fluorescence sensing was realized by 3D covalent organic framework (3D-LCOF) as molecular decoder for VOCs identification based on turn-on luminescence. 3D-LCOF was synthesized via [T4 + C4] imine condensation of TFBM and PyTTA. The structure of 3D-LCOF was confirmed by FT-IR, 13C CP-MAS solid state NMR and Powder X-ray diffraction. Structural simulation revealed that 3D-LCOF had three-dimensional pts topological structure with quadrilateral pores. 3D-LCOF present high BET surface area of 875 m2 g−1 with an average pore size of ∼0.85 nm. Due to the conjugated skeleton and unique porous structure, 3D-LCOF can accurately distinguish and locate more than twenty kinds of VOCs, including aromatic, alcohol-based and other industrial common VOCs. Furthermore, 3D-LCOF was also very efficient for the ultra-low detection of nitro pesticides at ppm levels (0.056 ppm for NA, 0.15 ppm for DCN). This study sheds lights on the design of porous framework sensor and expand the utilization of COF materials.

Characterization, luminescence and dye adsorption study of manganese and samarium doped and co-doped zinc sulfide phosphors

Luminescent materials are widely used for various applications such as light-emitting diodes (LEDs), thermoluminescence dating, phosphor thermometry, as well as phosphors. Zinc sulfide is one of the most common phosphors due to its facile preparation and relatively low materials cost. Herein, manganese-doped, samarium-doped, and co-doped zinc sulfides were successfully synthesized by a precipitation method. XRD results showed no other crystalline phases observed in the synthesized products. The synchrotron-XRF confirmed the successful incorporation of Mn and Sm into the doped and co-doped samples, in which approximately 10% of the initial doping amount of Mn and 1% of the initial concentration of Sm3+ were found. XAS analysis revealed the oxidation state and local structure of the manganese dopant and the zinc in the ZnS host matrix. SEM and TEM showed the agglomeration of nanoparticles into secondary particles with irregular shapes. A comparative study on the photoluminescence characteristics of the pristine ZnS and its corresponding doped phosphors thoroughly ensued. The result showed that all the samples had identical defect-derived fluorescence peaks. However, the addition of Mn2+ ion had led to the extra emission at the wavelength around the value of 607 nm corresponding to the 4T1 to 6A1 transition within the Mn2+ activator. Interestingly, the samarium dopant shifted both the excitation and the emission maxima up to 11 nm and 10 nm, respectively. These shifts were not very high due to the limited incorporation of the samarium in the ZnS structure, as suggested by the synchrotron-XRF study. Our work, therefore, showed the prospects of tuning the bandgap energy of the transition doped ZnS by the addition of rare-earth ions. The N2 sorption isotherms revealed the relatively high specific BET surface areas (~171–196 m2/g). Apart from the luminescent applications, the present samples are also prospectively candidates for anionic-dye adsorption due to their dye selectivity.

A three-in-one strategy for facile fabrication of hierarchically porous n-doped carbons: enhanced CO2 capture and tetracycline removal

The formation of high-quality hierarchically porous N-doped carbons with multi-scale pores, high specific surface area and large pore volume generally suffers from multistep complicated procedures. It still remains a great challenge to develop facile and effective approaches. Here, a novel three-in-one strategy (synergistic self-templating, self-activation and in-situ N-doping) was designed to fabricate hierarchically porous N-doped carbons (HPNCs) directly, via a one-pot carbonization using ethylenediaminetetraacetic acid tripotassium salt dehydrate (EDTA-3K) as the sole starting material. The as-obtained HPNCs exhibited 3D porous architecture, very high BET surface areas (e.g., 2787 m2 g−1), rich porosity and good nitrogen doping amounts, resulting in good CO2 capture capacity (e.g., 5.80 mmol g−1, at 273 K and 1.0 bar), and tetracycline adsorption ability (e.g., 1092 mg g−1). This discovery can provide a new concept for simply fabricating well-defined and unique functional porous carbons for various applications, such as sensor, energy storage and conversion, adsorption, separation, catalysis, bio-medicine, environmental protection.

Adsorption of lead(II) and chromium(VI) from aqueous environment onto metal-organic framework MIL-100(Fe): Synthesis, kinetics, equilibrium and thermodynamics

In present research, MIL-100(Fe) was efficiently synthesized by hydrothermal strategy applying HF as mineralizing agent and its ability was examined for lead(II) and chromium(VI) adsorption from an aqueous environment. Structural, chemical and morphological properties of the synthesized MOF were specified by different experimental techniques including XRD, FTIR, SEM, EDS and adsorption isotherms of N2 at 77 ​K (BET). D-spacing was measured with Debye–Scherrer’s formula as 7.98 ​Å. Also, the analyses confirmed relatively high BET surface area (1843.9 ​m2 ​g−1) and an octahedral-shaped structure for MIL-100(Fe) synthesized. Additionally, the adsorption behavior of lead(II) and chromium(VI) onto the MIL-100(Fe) was investigated using kinetics, equilibrium and thermodynamic parameters. Equilibrium analysis exhibited that the maximum uptake capacity for lead(II) was 23.46 ​mg ​g−1 based on sips model and for chromium(VI) was 30.45 ​mg ​g−1 ​by Langmuir isotherm. The sorption kinetics of lead(II) followed the pseudo 1st order model, while for chromium(VI) followed both pseudo 1st order and pseudo 2nd order models. Thermodynamic conclusions indicated a non-spontaneous nature for the sorption of each two metals and an exothermic reaction for lead(II) and endothermic nature for chromium(VI). Meanwhile, chemical ion-exchange and physisorption were distinguished as dominant adsorption mechanisms for lead(II) and chromium(VI), respectively.

Physico-chemical characterization of activated carbon synthesized from Datura metel's peels and comparative capacitive performance analysis in acidic electrolytes and ionic liquids

Oxygen-rich biomass-derived activated carbon is synthesized for electrode materials using Datura metel peels as precursor. Herein, a simple approach activation and carbonization at the same time is utilized to synthesize activated carbon. The as-prepared material exhibits high BET surface area ~818 m2/g and high mesopores volume ~0.85 cm3/g. Owing to its high oxygen content, supercapacitor was fabricated using the as-prepared activated carbon as electrode material. The calculated value of specific capacitance is 76.4 F/g in the potential window of 0.8 V at scan rate of 20 mV/s using 1 M sulfuric acid (H2SO4) as aqueous electrolyte, revealing good electrochemical performance of prepared electrode material. Furthermore, the assembled cell in the potential range 0–0.8 V yields an energy density of 6.79 Wh/kg at power density 24,450 W/kg. According to the above features, it can be suggested that Datura metel peel is a low cost, and green renewable candidate for the synthesis of activated carbon for its application as electrode material for high efficiency supercapacitor application.

Hypercrosslinked porous organic polymers based on tetraphenylanthraquinone for CO2 uptake and high-performance supercapacitor

We successfully synthesized two different kinds of hyper-crosslinked porous organic polymers (CPOPs) based on tetraphenylanthraquinone units by a reaction of 9,10-bis(diphenylmethylene)- 9,10-dihydroanthracene (An-4Ph) as the building unit with formaldehyde dimethyl acetal and 2,4,6-trichloro-1,3,5-triazine as two external crosslinkers by using a simple and friendly one-step Friedel−Crafts polymerization in the presence anhydrous FeCl3 as a catalyst to afford An-CPOP-1 and An-CPOP-2 as a black solid with high yield, respectively. Fourier-transform infrared (FTIR) and NMR spectroscopy were confirmed the chemical structures of the synthesized monomers and the corresponding polymers. Both An-CPOP-1 and An-CPOP-2 showed amorphous character, outstanding thermal stability, and high BET surface area (up to 1000 m2/g) with microporosity and mesoporosity architectures based on XRD, TGA analyses and N2 adsorption/desorption measurements. Interestingly, TEM and SEM images revealed that An-CPOP-1 had regular tubular nanotubes structure without using template or surfactant or carbonization at the elevated temperature. The as-prepared An-CPOP-2 exhibited a high specific capacitance of 98.4 F g−1 at a current density of 0.5 A g−1 and excellent cycling stability (95.3% capacitance retention over 2000 cycles), which could be used as good material for energy storage application.

A facile preparation of nitrogen-doped porous carbons from renewable as efficient catalysts for oxygen reduction reaction

Developing cost-effective and high active catalysts for the oxygen reduction reaction (ORR) is vital for the application of fuel cells. In this work, nitrogen-doped porous carbon nanosheets(N-PC) derived from biomass waste soybean residue were prepared by a facile combining method of solid state grinding and pyrolysing, using g-C3N4 as both nitrogen source and sacrificial template. The benefit of this facile process is that neither a designated template nor a chemical activating agent is required. The influence of g-C3N4 level on the structure and ORR behavior of the resulting N-PC was systematically investigated by means of spectroscopy (XPS), surface area analysis (BET), electron microscopy (TEM, SEM) et al., and electrochemical experiments. The optimized sample possesses appropriate defect structure, high BET surface area and pore volume (483 ​m2 ​g−1 and 1.57 ​cm3 ​g−1), and high N content (6.04 ​at.%), and exhibits decent activity and methanol tolerance in ORR process. Its superior stability versus the commercial Pt/C is also evidenced by almost 50% higher in chronoamperometric current response after 3600 ​s testing duration. This work supplies a simple and economical route to synthesize superior electrocatalyst for ORR on the basis of biomass waste.

Novel puffball–γ–MnO2 nanoparticles: preparation, Cu2+–modification, and application in photocatalytic decolorization of dyes

Puffball-like γ–MnO2 nanoparticles of about 40 ± 1 nm size, having a unique morphology and high BET surface area were synthesized under reflux conditions and subsequently modified with Cu2+. The as-synthesized nanoparticles were systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT–IR), N2 adsorption–desorption isotherms (BET) and energy dispersive X-ray analysis (EDX). The puffball–γ–MnO2 nanoparticles showed remarkable photocatalytic activity in treatment of wastewater and decolorization of dyes, especially Rhodamine 6G in presence of ultraviolet light–emitting diodes (UV–LEDs) irradiation. Under the optimized conditions, 91.5% decolorization was obtained for 200 mL of a 5 ppm solution of Rhodamine 6G within 40 min. It was also found that inclusion of Cu2+ has a significant positive effect (up to 17%) on the performance of these newly devised nanoparticles.

Enhanced Direct Dimethyl Ether Synthesis from CO2-Rich Syngas with Cu/ZnO/ZrO2 Catalysts Prepared by Continuous Co-Precipitation

The manufacturing of technical catalysts generally involves a sequence of different process steps, of which co-precipitation is one of the most important. In this study, we investigate how continuous co-precipitation influences the properties of Cu/ZnO/ZrO2 (CZZ) catalysts and their application in the direct synthesis of dimethyl ether (DME) from CO2/CO/H2 feeds. We compare material characteristics investigated by means of XRF, XRD, N2 physisorption, H2-TPR, N2O-RFC, TEM and EDXS as well as the catalytic properties to those of CZZ catalysts prepared by a semi-batch co-precipitation method. Ultra-fast mixing in continuous co-precipitation results in high BET and copper surface areas as well as in improved metal dispersion. DME synthesis performed in combination with a ferrierite-type co-catalyst shows correspondingly improved productivity for CZZ catalysts prepared by the continuous co-precipitation method, using CO2-rich as well as CO-rich syngas feeds. Our continuous co-precipitation approach allows for improved material homogeneity due to faster and more homogeneous solid formation. The so-called “chemical memory” stamped during initial co-precipitation is kept through all process steps and is reflected in the final catalytic properties. Furthermore, our continuous co-precipitation approach may be easily scaled-up to industrial production rates by numbering-up. Hence, we believe that our approach represents a promising contribution to improve catalysts for direct DME synthesis.

Porous Cr2O3@C composite derived from metal organic framework in efficient semi-liquid lithium-sulfur battery

A carbon composite including Cr2O3 (Cr2O3@C) and benefitting of a metal organic framework (MOF) precursor is herein synthesized, and originally employed in a semi-liquid lithium-sulfur cell using a catholyte solution formed by Li2S8 polysulfide, conducting lithium salt and film forming additive dissolved in diethylene glycol dimethyl ether (DEGDME). The adopted cell configuration may actually allow the porous structure of the MOF derivative to efficiently enable the lithium/sulfur electrochemical process. Thus, structure, chemical composition, morphology and porosity of the composite are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption/desorption isotherms, respectively. The data reveal a mesoporous material consisting of aggregated nanometric particles (<100 nm) with relatively high BET surface area (170 m2 g−1), uniform element distribution, and a carbon content of about 13 wt%. Cyclic voltammetry of the Cr2O3@C in semi-liquid lithium sulfur cell using the catholyte solution shows a reversible reaction with fast kinetics and Li-diffusion coefficient ranging from about 3 × 10−8 cm2 s−1 at 2.4 V vs. Li+/Li, to 1 × 10−8 cm2 s−1 at 2 V vs. Li+/Li. Furthermore, electrochemical impedance spectroscopy reveals a very stable interphase with an impedance below 5 Ω after an activation process promoted by cycling. The semi-liquid Li/S cell operates with remarkable stability and efficiency approaching 100%, delivers a capacity ranging from 900 mAh g−1 at C/10 rate to 780 mAh g−1 at C/3 rate, and performs over 100 charge/discharge cycles with very modest capacity decay.

K2O Doped Dolomite as Heterogeneous Catalyst for Fatty Acid Methyl Ester Production from Palm Oil

Biodiesel obtained from palm oil over an environmentally friendly catalyst is highlydesirable. For that matter, dolomite, a natural material was used as a catalyst in this work, and this included potassium oxide (K2O)-doped dolomite, 5 wt% K/D, 10 wt% K/D, 15 wt% K/D, and 20 wt% K/D. X-ray diffraction analysis of dolomite revealed the CaO and MgO phases with high crystallinity, in which intensity reduced after doped with varying concentrations of K2O. When the catalysts were evaluated, the K2O-doped dolomite exhibited a better catalytic activity for palm oil transesterification. In the presence of K2O, the methyl ester reached 98.7%, with the highest being displayed by 15 wt% K/D as compared to 87% over dolomite at reaction temperature of 60 °C, 12:1 methanol to palm oil ratio, 1 wt% catalyst amount and 1 h reaction time. SEM revealed that as more K2O was doped on dolomite, the particles became more agglomerated, with a reduced BET surface area of 1.3 m2/g in 20 wt% K/D as opposed to homogeneously small-sized MgO and CaO particles in dolomite with a high BET surface area of 19.0 m2/g. However, the high activity of the doped catalyst was dictated by the high amount of basic site, as evidenced in TPD-CO2 which showed an increase in the capacity of the basic site with an increased amount of K2O. The catalyst was also reusable up to six times with a negligible decrease in activity due to K+ leaching.

A comparison of Cu/CeO2 catalysts prepared via different precipitants/digestion methods for single stage water gas shift reactions

CeO2 supports have been synthesized through a different precipitation/digestion method with various cerium precursors (cerium hydroxide (CH), cerium hydroxy carbonate (CHC), cerium carbonate (CC)). Nano-sized CeO2 supports with a high BET surface area were prepared through the pre-calcination of cerium precursors. 20 wt.% of Cu was loaded onto the prepared CeO2 supports through an incipient wetness impregnation method. Among the prepared catalysts, Cu/CeO2-CHC yielded the highest CO conversion between the temperature range from 200 to 360 °C. This result was primarily due to possessing the highest Cu dispersion and a high oxygen storage capacity (OSC). In addition, the 20 wt.% Cu/CeO2 catalyst exhibited 100 % CO2 selectivity.

Nonhydrolytic sol-gel in-situ synthesis of novel recoverable amorphous Fe2TiO5/C hollow spheres as visible-light driven photocatalysts

A novel recoverable visible-light photocatalyst, amorphous Fe2TiO5/C composite, was prepared via nonhydrolytic sol-gel method with carbon-containing precursors as in-situ carbon sources. It is demonstrated that the precursors, iron ethoxide and butyl titanate, react to form Fe-O-Ti bonds in gel through a ether elimination reaction and amorphous Fe2TiO5 at 300 °C, which finally crystallizes at 600 °C. The residual organic groups form uniform-doped C. Interestingly, the photocatalytic activity of amorphous Fe2TiO5/C is distinctly superior to those of its crystalline counterparts without C and P25 (43-fold increase and 12-fold increase, respectively), which is mainly attributed to the incorporation of C (8.17 wt%) and amorphous Fe2TiO5 with a hollow spherical structure and a high BET surface area of 195.5 m2/g. Importantly, the photocatalyst can be recovered with a recovery rate of 100% simply by an external magnetic field, making it have promising applications in the wastewater treatment field.