Mesoporous Molecular Sieve SBA-15 Research Articles

Si,N co-doped carbon quantum dots in mesoporous molecular sieves: A fluorescence sensing platform for Cr(VI) detection

Carbon quantum dots (CQDs) are highly efficient fluorescent probes for metal ion detection; however, they are limited by non-uniform particle size, aggregation, and the inability to facilitate quantitative analysis. Herein, a smart host–guest strategy is utilized, wherein CQDs are immobilized in mesoporous molecular sieves, proving to be an effective method to minimize these drawbacks. Si,N-CQDs@SBA-15 is successfully synthesized by the one-step hydrothermal route using Si,N-CQDs precursor materials as guests and the mesoporous molecular sieve SBA-15 as the host. A good linear relationship between the concentration of Cr(VI) ions and fluorescent intensity is observed from 0 μM to 100 μM (R2 = 0.9986). Thelimitofdetection(LOD) is 0.213 μM, approximately three times lower than that of pristine Si,N-CQDs (0.677 μM). Additionally, Si,N-CQDs@SBA-15 exhibit good detection selectivity for Cr(VI) detection over other metal ions. Moreover, a smartphone-based laboratory device and RGB analysis app are employed to capture and analyze fluorescence images, revealing a LOD for Cr(VI) of 0.201 μM. Förster Resonance Energy Transfer (FRET) is identified as the possible mechanism for the fluorescence quenching of Si,N-CQDs@SBA-15 by Cr(VI) through UV–vis and fluorescence experiments. The practicability of the synthesized fluorescent probes is further validated in river water, yielding satisfactory spiked recoveries ranging from 99.24 % to 106.21 %.

In Vitro Synthesis of Isoprene by the Mevalonate Pathway in a Multi-step Enzyme Cascade Immobilized Biocatalyst Based on Mesoporous Molecular Sieve SBA-15

In Vitro Synthesis of Isoprene by the Mevalonate Pathway in a Multi-step Enzyme Cascade Immobilized Biocatalyst Based on Mesoporous Molecular Sieve SBA-15

Thermogravimetry Applied for Investigation of Coke Formation in Ethanol Conversion over Heteropoly Tungstate Catalysts

Thermogravimetric analysis (TGA) was used to evaluate the thermal stability and the amount of coke deposition resulting from the deactivation of catalysts during ethanol dehydration reaction in a fixed bed continuous flow reactor. In this study, a series of catalysts containing 30% of Pd doped and pure 12-tungstophosphoric acid and its insoluble Cs2.5H0.5PW12O40 salt supported on SBA-15 were prepared. The catalytic efficiency of ethanol dehydration reaction was also evaluated. Two types of coke are identified from the TPO (Temperature programmed oxidation) profiles and assigned to the coke precursor and hard coke, respectively. The results indicate that cesium salts reduced the formation of hard coke. The amount of total coke formed was significantly reduced by supporting the catalysts on mesoporous SBA-15 molecular sieves.

Surface Functionalization of SBA-15 for Immobilization of Myoglobin.

Mesoporous molecular sieve SBA-15 was successfully modified with 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTMS). The functionalized SBA-15 were characterized by small-angle X-ray (SAXRD), thermogravimetric analysis (TG), N2 adsorption, and Fourier transformed infrared spectrum (FT-IR). APTES functionalized SBA-15 (named SBA-15-A) and GPTMS functionalized SBA-15 (named SBA-15-G) were used to immobilize myoglobin (Mb). The loading amounts of Mb by SBA-15-A and SBA-15-G were 511.2 and 547.8 mg/g, respectively, whereas only 359.6 mg/g was achieved by SBA-15. Mb/SBA-15-G and Mb/SBA-15-A demonstrated better reusability than SBA-15, retaining 84.6% and 82.7% of the initial activity after repeated use seven times. The Mb/SBA-15-A and Mb/SBA-15-G also exhibited improved thermal stability and storage stability.

Facile immobilization of his-tagged Microbacterial esterase on Ni-SBA-15 with enhanced stability for efficient synthesis of key chiral intermediate of d-biotin.

A series of nickel-incorporated SBA-15 mesoporous molecular sieves (Ni-SBA-15) were prepared as support for the immobilization of his-tagged recombinant Microbacterium esterase. The Ni-SBA-15 could strongly and specific absorb the his-tagged esterase from cell disrupted supernatant. It was found that the nickel amount in Ni-SBA-15 has dramatic influence on the activity and thermo-stability of immobilized enzyme, while the kinds of nickel precursor had little effect on enzyme stability. The morphology, chemical composition and structure of the best support NiCl2-SBA-15 (Ni-SBA-15 prepared from NiCl2 precursor) were characterized by various spectroscopy techniques. The immobilized esterase retained full activity of free esterase and showed high immobilized yield (> 90%) with higher thermo-stability, pH stability and organic solvent resistance compared with free enzyme. The optimum reaction temperature increased from 35 to 40°C and the optimal reaction pH moved from 10.0 to 8.0 after enzyme immobilization. The immobilized esterase exhibited excellent storage stability and keeping 92% of the initial activity after 30days' storage at 25°C. In addition, the immobilized esterase had excellent reusability for the synthesis of key chiral intermediate of d-biotin and the substrate conversion could still keep 100% after 13 cycles continuously. Finally, optical pure (4S, 5R)-hemiester was obtained in 80.8% isolated yield and 99% purity in the gram preparative scale.

Improving sorption performance of amolecularly imprinted monolithic column by doping mesoporous molecular sieve SBA-15.

For the first time a hybrid molecularly imprinted polymer (MIP)doped with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS)-modified mesoporous molecular sieve SBA-15 for target peptide recognitionhas been developed. Zinc acrylate and methacrylic acid were used as binary functional monomers, and ethylene dimethacrylate was used as cross-linking agent to prepare animprinted monolith against Val-Tyr-Ala-Leu-Lys(glutarylation) (VYALKglu). The morphology of the polymers was characterized by scanning electron microscopy, FT-IR spectroscopy, energy dispersive spectroscopy, and 1H NMR. The SBA-15-MPS MIP showed high recovery of 87.1% and the IF of 12.9 for the enrichment of the template peptide. When the template peptide concentration ranged from 5 to 90μgmL-1, the correlation coefficients (R2) for the calibration function obtained was better 0.999. The limit of detection (LOD, 0.30μgmL-1) and limit of quantification (LOQ, 1.0μgmL-1) were achieved for signal-to-noise ratios of 3:1 and 10:1, respectively. When other kinds of synthetic peptides were used as analogs, the selectivity of the SBA-15-MPS MIP was much better than the SBA-15-MPS NIP (without template peptides)with relative selectivity coefficients of 52.8-265. In contrast, little quinolones and biogenic amines areadsorbed with the SBA-15-MPS MIP. The SBA-15-MPS MIP could enrich VYALKglu from spiked histone digestion with the average recovery of 87.8% and the relative standard deviation (RSD) of 0.99%. As a conclusion, doping of SBA-15 is an effective approach to the improvement of performance of molecularly imprinted monolith.

A Microfluidic Platform for Proteomics Based on Enzyme Reactor Monolith Incorporated with Mesoporous Molecular Sieve Sba-15

A Microfluidic Platform for Proteomics Based on Enzyme Reactor Monolith Incorporated with Mesoporous Molecular Sieve Sba-15

Activation of peroxymonosulfate by bimetallic CoMn oxides loaded on coal fly ash-derived SBA-15 for efficient degradation of Rhodamine B

• Mesoporous SBA-15 is successfully synthesized with coal fly ash as the silicon source. • CoMn/SBA-15 exhibits excellent performance for RhB degradation by activating PMS. • Synergistic effects of Co and Mn species are inferred. • Non-radical ( 1 O 2 ) rather than radicals (SO 4 − and OH) contributes most to the degradation. • Mechanisms of PMS activation and the degradation pathways of RhB are proposed. In this study, we successfully synthesized SBA-15 mesoporous molecular sieve with coal fly ash (CFA) as the silicon source, fabricated bimetallic CoMn catalysts with the obtained SBA-15 as the support, and evaluated their performance for activating peroxymonosulfate (PMS) to degrade the Rhodamine B (RhB) in an aqueous solution. The characterization results signified that MnCo 2 O 4 spinel was formed and uniformly dispersed on SBA-15 for the as-prepared CoMn/SBA-15. The CoMn/SBA-15/PMS system exhibited markedly higher RhB removal efficiency compared with Co/SBA-15/PMS and Mn/SBA-15/PMS under the same reaction conditions. Moreover, bimetallic CoMn/SBA-15 presented much lighter metal leaching than the monometallic catalysts. Chemical quenching tests and electron paramagnetic resonance experiments ascertained the generation of free radicals (SO 4 − and OH) and non-radical (singlet oxygen, 1 O 2 ) reactive oxygen species by PMS activation and the dominant role 1 O 2 in RhB degradation. The formed intermediate products by RhB degradation were identified with LC-MS analyses. We have also performed LC-MS analyses to determine the formed intermediate products during RhB degradation. The present results demonstrate the pronounced potential of CFA as a silicon source of molecular sieve support for preparing various heterogeneous catalysts for the PMS-based oxidation of organic pollutants in wastewater.

Preparation and electrochemical hydrogen storage application of mesoporous carbon CMK-3 coated Co2B alloy composite

Mesoporous carbon CMK-3 is synthesized using mesoporous molecular sieve SBA-15 as the template. Co2B alloy is prepared by the high temperature solid phase method. Composites of Co2B mixed with 2%, 5%, 7% and 10% of CMK-3 are fabricated via ball-milling to improve the electrochemical performance of Co2B alloy. Ultimately, the discharge capacity reaches a maximum (662.8 mAh/g) for 5% doping amount of CMK-3. The CMK-3/Co2B composite materials exhibit preferable HRD and improved corrosion and oxidation resistance. CMK-3/Co2B displays excellent electrochemical and kinetics properties owing to the unique electrocatalytic activity and structural feature of CMK-3, which can accelerate the hydrogen transmission.

Ion-Imprinted Polymer Modified with Carbon Quantum Dots as a Highly Sensitive Copper(II) Ion Probe.

Fluorescence analysis technology and ion imprinting technology are combined to prepare a copper ion fluorescence sensor. Carbon quantum dots (CQDs), with a quantum yield of 79%, were synthesized by a hydrothermal process using citric acid as the carbon source. The prepared CQDs, acting as the fluorophore, were grafted onto the surface of an SBA-15 mesoporous molecular sieve by an amidation reaction. Then, the fluorescent sensor CQDs@Cu-IIP was prepared using a surface imprinting technique with the modified SBA-15 as the substrate, copper ions as a template, tetraethoxysilane as the crosslinker, and 3-aminopropyl-3-ethoxysilane as the functional monomers. The sensor showed strong fluorescence from CQDs and high selectivity due to the presence of Cu(II)-IIP. After the detection conditions were optimized, the fluorescence intensity of the sensor had good linearity with Cu(II) concentration in a linear range of 0.25–2 mg/L and 3–10 mg/L. This CQDs@Cu-IIP was applied to the determination of traces Cu(II) in real water samples and good recoveries of 99.29–105.42% were obtained. The present study provides a general strategy for fabricating materials based on CQDs for selective fluorescence detection of heavy metals.

Near-room temperature transesterification over bifunctional CunO-Bs/SBA-15 catalyst for biodiesel production

The transesterification of triglycerides is a critical step in biodiesel production. In this work, by loading boron-doped copper oxides onto SBA-15 mesoporous molecular sieve, an acid-base bifunctional catalyst (i.e., CunO-Bs/SBA-15) was prepared and applied to triglyceride transesterification. Compared with pure copper, sodium or boron oxides-based catalysts, CunO-Bs/SBA-15 enabled a higher biodiesel yield (>97.5%) at near room temperature (i.e., 40 °C) in 120 min. The characterization results showed that after B doping, the CunO-Bs/SBA-15 catalyst contained highly-dispersed acid-base sites without blocking the channels of porous SBA-15 support, which had good catalytic performance. Finally, in-situ DRIFTS was used to reveal the catalytic mechanism of the acid-base bifunctional groups of the as-prepared CunO-Bs/SBA-15 during transesterification.

Capturing Carbon Dioxide on the Wet SBA-15 Mesoporous Molecular Sieves with Different Surfactants

SBA-15 mesoporous molecular sieves were used as the adsorption medium to capture carbon dioxide by the gas hydrate method. First, it is confirmed that the synthesized SBA-15 material has a uniform ...

The effect of hydrothermal temperature on the properties of SBA-15 materials

In present work, ordered mesoporous material SBA-15 was synthesized by using poly (alkylene oxide) block copolymer (Pluronic P123) as template and ethylsilicate as silica source in weak acid environment in a wide range of temperature. The focus of synthesis research was high hydrothermal temperature. The obtained products were characterized by various techniques, including XRD, N2 sorption isotherms, FTIR spectroscopy and thermogravimetric. The effect of hydrothermal temperature on the specific surface area, pore volume and pore size of SBA-15 products was investigated systematically. As the hydrothermal temperature increases from the 100–120 °C, the specific surface area and the pore volume of the mesoporous molecular sieve increase greatly. When the hydrothermal temperature increase further, the pore volume of the mesoporous molecular sieve increase continually. But the specific surface area decrease significantly. When the hydrothermal temperature is too high (over 140 °C), the order degree begins to decrease, So the specific surface area and pore volume decrease significantly because the pores structure have significant destruction and collapse. Mechanism and structural characteristics of P123 block copolymer could explain in detail the effect of hydrothermal temperature on the property and structure of mesoporous molecular sieve SBA-15.

Aluminium-induced component engineering of mesoporous composite materials for low-temperature NH3-SCR

Supported Mn2O3 is useful in achieving high dinitrogen selectivity at low temperature during ammonia-selective catalytic reduction (SCR). However, its controlled synthesis is challenging when the supporting material is the conventional pure silicon SBA-15 mesoporous molecular sieve. Here we show that silicon and aluminium in fly ash, the solid waste produced by coal-fired power plants, can be used to synthesize an Al-SBA-15 mesoporous molecular sieve support, which can guide the growth of Mn2O3 in the as-synthesized Fe-Mn/Al-SBA-15 NH3-SCR catalyst. Its superior catalytic performance is demonstrated by the high NOx conversion (≥90%) and selectivity (≥86%) at low temperatures (150–300 °C). The combined theoretical and experimental results reveal that the introduction of Al induces the growth of Mn2O3 catalysts. Our findings, therefore, provide a strategy for the rational design of low-temperature NH3-SCR catalysts through dopant-induced component engineering of composite materials.

Zinc-tetraphenylporphyrin grafted on functionalised mesoporous SBA-15: synthesis and utilisation for nitroaldol condensation

Functional free-tetraphenylporphyrin (TPP) molecule was prepared by simple one-step method and subsequently zinc ion was introduced in the cavities of TPP (Zn-TPP). The prepared functional free Zn-TPP was grafted by covalent bonding of zinc with amine functionality present on the internal surface of organo-functionalised mesoporous SBA-15 molecular sieves through axial position. The resultant material was completely characterised using various analytical and spectroscopic techniques including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy, proton nuclear magnetic resonance, X-ray powder diffraction, thermo-gravimetry–differential thermal analysis, 13C magic-angle spinning nuclear magnetic resonance (MAS-NMR), N2 physisorption studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The presence of organo-functionality and Zn-TPP on the surface was confirmed by conducting 13C MAS-NMR and FT-IR studies. Often, zinc containing functional porphyrin derivatives have shown as potential biological, luminescent properties, whereas in the present studies the functional free Zn-TPP and heterogenised functional-free Zn-TPP materials (SBA-15-AM-Zn-TPP) explored for the first time as catalytic materials for nitroaldol condensation under varying reaction conditions. The present functional free Zn-TPP has an advantage of ease on preparation and strong interaction on the surface linker through axial position, which made it a potential catalyst for aldol condensation and exhibit promising catalytic activity.

Study on the controlled synthesis of Zr/TiO2/SBA-15 nanophotocatalyst and its photocatalytic performance for industrial dye reactive red X–3B

Nanophotocatalytic technology is one of the most promising technologies to treat industrial dyes in waste water. Nanosized TiO2 was loaded on mesoporous SBA-15 molecular sieve by chemical method to prepare TiO2/SBA-15 (TS1) in this work. Then, the transition metal element Zr was further deposited on the surface of TS1 to obtain Zr/TiO2/SBA-15 (ZTS) nanophotocatalysts. The crystal structure, morphology, element distribution and pore size distribution of several samples were studied using small-angle x-ray scattering, X-ray diffraction, Transmission electron microscope, Scanning electron microscope, X-ray photoelectron spectroscopy, N2 adsorption-desorption, UV–Vis diffuse reflectance spectroscopy. The photocatalytic performance of the nanophotocatalyst was evaluated by photocatalyzing reactive red X–3B. The results show that the ZTS nanophotocatalyst has a good mesoporous structure, wherein, the TiO2 is an anatase phase. The specific surface of ZTS reaches 538.24 m2/g and its spectral absorption threshold reaches 425 nm. When the deposition amount of Zr is moderate the ZTS nanophotocatalyst shows quite high photocatalytic activity. In pH 2–10, the photocatalytic activity of ZTS exhibits change with variation of pH value. Under proper conditions, the degradation rate of reactive red X–3B reaches about 96% in ZTS photocatalytic system. Therefore, ZTS nanophotocatalyst has great potential in the treatment of dye wastewater.

Performance of Brӧnsted-Lewis acidic ionic liquids supported Ti-SBA-15 for the esterification of acetic acid to benzyl alcohol

Brӧnsted-Lewis acidic ionic liquids (BLAILs)[3-methyl-1-(3-sulfonic acid) imidazolium zinc sulfate ([MIMPS]+(1/2Zn2+)SO42−)] with Brӧnsted acid ionic liquid [MIMPS]+HSO4- and ZnO were synthesized, and their acidities were determined by infrared pyridine probe. Ti doped SBA-15 mesoporous molecular sieves (Ti-SBA-15) were synthesized by co-condensation method. Ionic liquid [MIMPS]+(1/2Zn2+)SO42− and Ti-SBA-15 are compounded at different mass ratios by impregnation method. FT-IR, TG, XRD, N2 physical adsorption, elemental analysis, mass spectroscopy, TEM, and XPS were used to characterize the composition and structure of the catalysts. The catalytic activities of catalysts were investigated via esterification of acetic acid with benzyl alcohol (BnOH). When the reaction temperature is 90 ℃, reaction time is 3 h, nbenzyl alcohol/nacetic acid =1.8, and the amount of catalyst was 0.4 g, the conversion of acetic acid was as high as 93.8 %. After 5 cycles, the conversion of acetic acid decreased only 5%, suggesting that the resulting catalyst had good stability.

Catalytic activity of heteropoly tungstate catalysts for ethanol dehydration reaction: Deactivation and regeneration

The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its cesium salts CsxH3-xPW12O40 (x = 1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. In this paper were determined the optimal reaction temperature and the effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200−350 °C. Above 300 °C, a strong deactivation of the catalysts was caused by coke formation. The catalytic tests demonstrate that by supporting the HPW and PdyPW (y = 0.15, 0.2 and 0.25) on mesoporous molecular sieve SBA-15 the catalytic activity in ethanol dehydration reaction was improved. Palladium doping of HPW/SBA-15 significantly decreases the formation of coke deposit. The formation of coke during the ethanol dehydration does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.

Ultrasound-enhanced matrix solid-phase dispersion micro-extraction applying Mesoporous Molecular Sieve SBA-15 for the determination of multiple compounds in Fructus Psoraleae

An efficient ultrasound enhanced matrix solid-phase dispersion micro-extraction method was established for the extraction and determination of multiple ingredients (psoralenoside, isopsoralenoside, psoralen, isopsoralen, bavachin, psoralidin, isobavachalcone and bakuchiol) from Fructus Psoraleae applying ultra-high-performance liquid chromatography. The experimental factors affecting the extraction efficiency, including extraction solvent concentration, extraction solvent volume and ultrasound time, were optimized by the design of experiments methodology. Central composite design was applied in this optimization approach as a quadratic model. Under optimum conditions, good linear regression (r2 > 0.9999) and recovery (96.8%–104%, RSD<3.73%) for targets were attained. In addition, the intra-day of analytes was below 4.42% and inter-day precision of analytes was below 2.08%. This proposed method only required small amounts of reagent (0.5 mL) and materials usage (20 mg). Thus, the present study applied the efficient method to exhibit fast preparation and determination of eight ingredients of continents in Fructus Psoraleae.

Effect of additive on CuO-ZnO/SBA-15 catalytic performance of CO2 hydrogenation to methanol

AbstractThree kinds of porous catalysts CuO-ZnO/SBA-15 (CZ/SBA-15), CuO-ZnO-MnO2/SBA-15 (CZM/SBA-15) and CuO-ZnO-ZrO2/SBA-15 (CZZ/SBA-15) were synthesized by impregnation method with a siliceous framework mesoporous molecular sieve SBA-15. The performance of all catalysts for catalytic hydrogenation of CO2 to methanol was evaluated on a fixed bed reactor, combined with N2 adsorption-desorption (BET), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), temperature programmed desorption (H2-TPD, CO2-TPD), N2O titration, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) . The results show that the introduction of metal oxide in the catalyst changes the pore size and specific surface area of the SBA-15 molecular sieve support. The CuO-ZnO-MnO2/SBA-15 and CuO-ZnO-ZrO2/SBA-15 have high copper dispersion (DCu), large specific surface area (ACu), small surface CuO particle size, and easy to be reduced. Compared with the Mn-O cluster, the Zr-O cluster enhances the basic site and improves the methanol selectivity. In addition, CuO-ZnO-ZrO2/SBA-15 has the highest oxygen vacancy concentration and better catalytic activity among three catalysts. The methanol selectivity of CuO-ZnO-ZrO2/SBA-15 is 25.02%, which is 28% and 136.9% higher than those of CuO-ZnO/SBA-15 and CuO-ZnO-MnO2/SBA-15, respectively.