Using cetyl-trimethyl-ammonium bromide (CTMAB) as the template agent and tetraethylorthosilicate (TEOS) as the silica source, the MCM-41 mesoporous materials were synthesized with La or Ce incorporated in the fram...Using cetyl-trimethyl-ammonium bromide (CTMAB) as the template agent and tetraethylorthosilicate (TEOS) as the silica source, the MCM-41 mesoporous materials were synthesized with La or Ce incorporated in the framework under hydrothermal conditions. The structure and the state of La or Ce were investigated through the analyses of XRD, nitrogen adsorption-desorption, FT-IR, and UV-Vis. XRD and N2 adsorption-desorption results showed that Ln-MCM-41 exhibited the loss of the lattice ordering of the MCM-41 construct, and larger unit cell parameter and pore diameter than pure silica MCM-41. The FT-IR and UV-Vis results indicated the presence of isolated tetra-coordinated La or Ce ions in the framework and other Ln species dispersed highly on the Ln-MCM-41 surface simultaneously. Furthermore, their catalytic behaviors in the oxidation of styrene were studied using H2O2 as the oxidant. The La-MCM-41 catalysts exhibited high reactivity and the reactivity increased with the increase of the La content in the La-MCM-41 samples. On the contrary, Ce-MCM-41 catalysts showed low reactivity in the oxidation of styrene and the conversion of styrene decreased with the increase of the Ce content in the Ce-MCM-41 samples.展开更多
Using cetyl-trimethyl-ammonium bromide (CTMAB) as template and tetraethylortho-silicate (TEOS) as silica source, the MCM-41 mesoporous materials incorporated in framework by Y, Nd and Sm were synthesized by hydrot...Using cetyl-trimethyl-ammonium bromide (CTMAB) as template and tetraethylortho-silicate (TEOS) as silica source, the MCM-41 mesoporous materials incorporated in framework by Y, Nd and Sm were synthesized by hydrothermal synthesis method. The structure, morphology of materials and the state of Y, Nd, Sm in materials were investigated by means of XRD, nitrogen adsorption-desorption, SEM, IR spectrometry, TG-DTA. The XRD results indicate that the samples possess the mesoporous MCM-41 structures with ordered hexagonal arrangements. Y, Nd and Sm ions can get into the framework of mesoporous materials. Nitrogen adsorption desorption isotherms show that the samples have typical mesopores characteristics. SEM micrographs reveal that incorporated sampies show a spherical morphology and the diameters are averagely 0. l0 to 0.15 μm. In IR spectrum of samples, there are the feature adsorption peaks about Si-O-Ln(Ln=Y, Sm, Nd)at 960-985 cm^-1, which affirm that Y, Nd, Sm ions locate in the framework of several mesoporous materials. Results from TG-DTA analysis suggest that two different template sorption sites exist in the framework of YMCM-41, SmMCM-41, NdMCM-41, which powerfully proves that the presence of Y, Nd and Sm in Si framework of the materials.展开更多
Using cetyl-trimethyl-ammonium bromide (CTMAB) as template agent and tetraethylorthosilicate (TEOS) as silica Source, the MCM-41 mesoporous materials were synthesized with Y, Nd and Sm incorporated in the framewor...Using cetyl-trimethyl-ammonium bromide (CTMAB) as template agent and tetraethylorthosilicate (TEOS) as silica Source, the MCM-41 mesoporous materials were synthesized with Y, Nd and Sm incorporated in the framework under hydrothermal conditions. The structure and the micro-morphology of the materials and the state of Y, Nd and Sm were investigated through the analyses of XRD, nitrogen adsorption-desorption isotherm, SEM, IR and TG-DTA. The XRD resuits indicate that the synthetic samples are of typical structure of mesoporous MCM-41 with ordered hexagonal arrangements, and Y, Nd and Sm can be incorporated into the framework of these mesoporous materials. Nitrogen adsorption-desorption isotherms show that the samples possess the typical mesopores character. SEM micrographs reveal that the incorporated samples show a well-defined spherical morphology with the diameter ranging 0.10 - 0.15μm. The occurrence of two different template sorption sites in the framework as revealed by TG-DTA analysis further suggests the presence of Y, Nd and Sm in siliceous framework.展开更多
Sulfhydryl MCM-41(SH-MCM-41) mesoporous materials were prepared via a hydrothermal method,and-SH was successfully imported by a post-grafting method.The structure and surface properties of the materials were character...Sulfhydryl MCM-41(SH-MCM-41) mesoporous materials were prepared via a hydrothermal method,and-SH was successfully imported by a post-grafting method.The structure and surface properties of the materials were characterized using Fourier Transform infrared spectroscopy,X-ray diffraction and Transmission Electron Microscopy analysis.The low concentrations of La^3+,Gd^3+ and Yb^3+ adsorption on the material were investigated.This paper discusses the effects of system factors,such as pH and the solid-liquid ratio,on the performance of the adsorption process.The adsorption thermodynamics and kinetics were also explored.Experimental results indicated that the materials were in good order and had high specific surface area(956 m^2/g) with an average pore diameter of 2.1 nm;the mercapto groups were successfully grafted onto a molecular sieve,and the best grafted amount was 1.46×10^-3 mol/g.The materials showed preferable adsorption of La^3+,Gd^3+ and Yb^3+ with maximum adsorption capacities of560.56 mg/g,467.60 mg/g and 540.68 mg/g,respectively.The adsorption process can be described by the Freundlich isotherm model,and the adsorption data fits pseudo-second-order kinetics.After repeating the elution-regeneration cycle four times,the adsorption capacity of rare earth ions was mostly maintained,indicating that the adsorbent can be regenerated well and recycled to save costs.It has potential in practical application.展开更多
Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCh.SH2O was reacted with the Schiff base ligands for complex formation. The structural pr...Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCh.SH2O was reacted with the Schiff base ligands for complex formation. The structural properties of the synthesized materials were investigated by a number of analytical techniques including X-ray diffraction, N2 sorption-desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscpopy, and energy dispersive X-ray spectroscopy. Catalytic studies of the mesoporous materials functionalized with Zr(IV)-Schiff base complexes were investigated and extended to selective oxida- tion of sulfides to sulfoxides and the Knoevenagel condensation reactions of aldehydes with malo- nonitriles and ethyl cyanoacetate. Additionally, catalyst recycling of the Zr-salen-MCM-41 materials was also studied.展开更多
Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impreg...Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.展开更多
From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel a...From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.展开更多
Mesoporous silicon oxynitrides MCM-41 were synthesized successfully. The resulting materials not only have high nitrogen contents and good structural characteristics of MCM-41 (high surface area, narrow pore size dist...Mesoporous silicon oxynitrides MCM-41 were synthesized successfully. The resulting materials not only have high nitrogen contents and good structural characteristics of MCM-41 (high surface area, narrow pore size distribution and good order), but also are amorphous. The composition and structure of the materials were investigated by CNH element analysis, XPS, Si MAS NMR, XRD, HRTEM and N-2 sorption, respectively. Mesoporous silicon oxynitrides MCM-41 with a high nitrogen content are still non-crystal (amorphous).展开更多
Fluoride above 1.5 mg<span><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span></span>L...Fluoride above 1.5 mg<span><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span></span>L<sup><span style="color:#4f4f4f;">-</span></sup><sup>1</sup> is injurious to health. Removal of fluoride from water using mesoporous MCM-41 as a strong adsorbent material has been attempted. Characterization using transmission electron microscopic study of calcined MCM-41 showed the regular hexagonal array of mesoporous channels with <span style="font-family:;" "="">an </span><span style="font-family:;" "="">average size of 20 nm and the surface area (BET study) of 1306.96 m<sup>2</sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>g<sup><span style="color:#4f4f4f;">-</span></sup></span><sup>1</sup>. The average pore size of the particles was found to be 14.21 nm. <span style="font-family:;" "="">A </span><span style="font-family:;" "="">study on the effect of contact time on the removal of fluoride revealed that more than 85% uptake of fluoride onto MCM-41 was achieved at a contact time of 120 min. From </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">Langmuir adsorption study, the maximum sorption capacity of fluoride was found to be 63.05 mg/g at 301 K. From </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">thermodynamic study, the +ΔH<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">o</span> value of 2.29 kJ<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>mol<sup><span style="white-space:normal;"><sup></sup></span><span style="white-space:normal;color:#4f4f4f;">-</span></sup></span><sup>1</sup> indicated the endothermic nature of the removal process. Application of Response Surface Model suggested that 77.88% of fluoride removal can be achieved at fluoride concentration of 10 mg<span><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span></span>L<sup>-</sup><sup>1</sup>, pH (6.3)<span style="font-family:;" "="">,</span><span style="font-family:;" "=""> and contact time of 120 min.</span>展开更多
Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be...Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nsurf/nsi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.展开更多
Mesoporous molecular sieve MCM-41 has been synthesized in the extremely dense system (with H2O/Si<10) and characterized by XRD, N-2 adsorption isotherm as well as probe reactions of cracking of cumene and isomeriza...Mesoporous molecular sieve MCM-41 has been synthesized in the extremely dense system (with H2O/Si<10) and characterized by XRD, N-2 adsorption isotherm as well as probe reactions of cracking of cumene and isomerization of o-xylene.展开更多
The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 w...The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.展开更多
基金Project supported by the National Basic Research Program of China (2004CB719500)the Commission of Science and Technology of Shanghai Municipality (03DJ14006)
文摘Using cetyl-trimethyl-ammonium bromide (CTMAB) as the template agent and tetraethylorthosilicate (TEOS) as the silica source, the MCM-41 mesoporous materials were synthesized with La or Ce incorporated in the framework under hydrothermal conditions. The structure and the state of La or Ce were investigated through the analyses of XRD, nitrogen adsorption-desorption, FT-IR, and UV-Vis. XRD and N2 adsorption-desorption results showed that Ln-MCM-41 exhibited the loss of the lattice ordering of the MCM-41 construct, and larger unit cell parameter and pore diameter than pure silica MCM-41. The FT-IR and UV-Vis results indicated the presence of isolated tetra-coordinated La or Ce ions in the framework and other Ln species dispersed highly on the Ln-MCM-41 surface simultaneously. Furthermore, their catalytic behaviors in the oxidation of styrene were studied using H2O2 as the oxidant. The La-MCM-41 catalysts exhibited high reactivity and the reactivity increased with the increase of the La content in the La-MCM-41 samples. On the contrary, Ce-MCM-41 catalysts showed low reactivity in the oxidation of styrene and the conversion of styrene decreased with the increase of the Ce content in the Ce-MCM-41 samples.
文摘Using cetyl-trimethyl-ammonium bromide (CTMAB) as template and tetraethylortho-silicate (TEOS) as silica source, the MCM-41 mesoporous materials incorporated in framework by Y, Nd and Sm were synthesized by hydrothermal synthesis method. The structure, morphology of materials and the state of Y, Nd, Sm in materials were investigated by means of XRD, nitrogen adsorption-desorption, SEM, IR spectrometry, TG-DTA. The XRD results indicate that the samples possess the mesoporous MCM-41 structures with ordered hexagonal arrangements. Y, Nd and Sm ions can get into the framework of mesoporous materials. Nitrogen adsorption desorption isotherms show that the samples have typical mesopores characteristics. SEM micrographs reveal that incorporated sampies show a spherical morphology and the diameters are averagely 0. l0 to 0.15 μm. In IR spectrum of samples, there are the feature adsorption peaks about Si-O-Ln(Ln=Y, Sm, Nd)at 960-985 cm^-1, which affirm that Y, Nd, Sm ions locate in the framework of several mesoporous materials. Results from TG-DTA analysis suggest that two different template sorption sites exist in the framework of YMCM-41, SmMCM-41, NdMCM-41, which powerfully proves that the presence of Y, Nd and Sm in Si framework of the materials.
文摘Using cetyl-trimethyl-ammonium bromide (CTMAB) as template agent and tetraethylorthosilicate (TEOS) as silica Source, the MCM-41 mesoporous materials were synthesized with Y, Nd and Sm incorporated in the framework under hydrothermal conditions. The structure and the micro-morphology of the materials and the state of Y, Nd and Sm were investigated through the analyses of XRD, nitrogen adsorption-desorption isotherm, SEM, IR and TG-DTA. The XRD resuits indicate that the synthetic samples are of typical structure of mesoporous MCM-41 with ordered hexagonal arrangements, and Y, Nd and Sm can be incorporated into the framework of these mesoporous materials. Nitrogen adsorption-desorption isotherms show that the samples possess the typical mesopores character. SEM micrographs reveal that the incorporated samples show a well-defined spherical morphology with the diameter ranging 0.10 - 0.15μm. The occurrence of two different template sorption sites in the framework as revealed by TG-DTA analysis further suggests the presence of Y, Nd and Sm in siliceous framework.
文摘Sulfhydryl MCM-41(SH-MCM-41) mesoporous materials were prepared via a hydrothermal method,and-SH was successfully imported by a post-grafting method.The structure and surface properties of the materials were characterized using Fourier Transform infrared spectroscopy,X-ray diffraction and Transmission Electron Microscopy analysis.The low concentrations of La^3+,Gd^3+ and Yb^3+ adsorption on the material were investigated.This paper discusses the effects of system factors,such as pH and the solid-liquid ratio,on the performance of the adsorption process.The adsorption thermodynamics and kinetics were also explored.Experimental results indicated that the materials were in good order and had high specific surface area(956 m^2/g) with an average pore diameter of 2.1 nm;the mercapto groups were successfully grafted onto a molecular sieve,and the best grafted amount was 1.46×10^-3 mol/g.The materials showed preferable adsorption of La^3+,Gd^3+ and Yb^3+ with maximum adsorption capacities of560.56 mg/g,467.60 mg/g and 540.68 mg/g,respectively.The adsorption process can be described by the Freundlich isotherm model,and the adsorption data fits pseudo-second-order kinetics.After repeating the elution-regeneration cycle four times,the adsorption capacity of rare earth ions was mostly maintained,indicating that the adsorbent can be regenerated well and recycled to save costs.It has potential in practical application.
基金Financial support to this work by the Ilam University
文摘Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCh.SH2O was reacted with the Schiff base ligands for complex formation. The structural properties of the synthesized materials were investigated by a number of analytical techniques including X-ray diffraction, N2 sorption-desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscpopy, and energy dispersive X-ray spectroscopy. Catalytic studies of the mesoporous materials functionalized with Zr(IV)-Schiff base complexes were investigated and extended to selective oxida- tion of sulfides to sulfoxides and the Knoevenagel condensation reactions of aldehydes with malo- nonitriles and ethyl cyanoacetate. Additionally, catalyst recycling of the Zr-salen-MCM-41 materials was also studied.
基金financial supportfrom PRAMX 98-05 and helpful discussion with Dr.A.C.Franville.
文摘Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.
文摘From a basic solution containing celyltrimethylammonium cations as the template, thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.
文摘Mesoporous silicon oxynitrides MCM-41 were synthesized successfully. The resulting materials not only have high nitrogen contents and good structural characteristics of MCM-41 (high surface area, narrow pore size distribution and good order), but also are amorphous. The composition and structure of the materials were investigated by CNH element analysis, XPS, Si MAS NMR, XRD, HRTEM and N-2 sorption, respectively. Mesoporous silicon oxynitrides MCM-41 with a high nitrogen content are still non-crystal (amorphous).
文摘Fluoride above 1.5 mg<span><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span></span>L<sup><span style="color:#4f4f4f;">-</span></sup><sup>1</sup> is injurious to health. Removal of fluoride from water using mesoporous MCM-41 as a strong adsorbent material has been attempted. Characterization using transmission electron microscopic study of calcined MCM-41 showed the regular hexagonal array of mesoporous channels with <span style="font-family:;" "="">an </span><span style="font-family:;" "="">average size of 20 nm and the surface area (BET study) of 1306.96 m<sup>2</sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>g<sup><span style="color:#4f4f4f;">-</span></sup></span><sup>1</sup>. The average pore size of the particles was found to be 14.21 nm. <span style="font-family:;" "="">A </span><span style="font-family:;" "="">study on the effect of contact time on the removal of fluoride revealed that more than 85% uptake of fluoride onto MCM-41 was achieved at a contact time of 120 min. From </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">Langmuir adsorption study, the maximum sorption capacity of fluoride was found to be 63.05 mg/g at 301 K. From </span><span style="font-family:;" "="">the </span><span style="font-family:;" "="">thermodynamic study, the +ΔH<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#ffffff;"="">o</span> value of 2.29 kJ<span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span>mol<sup><span style="white-space:normal;"><sup></sup></span><span style="white-space:normal;color:#4f4f4f;">-</span></sup></span><sup>1</sup> indicated the endothermic nature of the removal process. Application of Response Surface Model suggested that 77.88% of fluoride removal can be achieved at fluoride concentration of 10 mg<span><span style="color:#4F4F4F;font-family:-apple-system, " font-size:16px;white-space:normal;background-color:#f7f7f7;"="">·</span></span>L<sup>-</sup><sup>1</sup>, pH (6.3)<span style="font-family:;" "="">,</span><span style="font-family:;" "=""> and contact time of 120 min.</span>
文摘Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nsurf/nsi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.
文摘Mesoporous molecular sieve MCM-41 has been synthesized in the extremely dense system (with H2O/Si<10) and characterized by XRD, N-2 adsorption isotherm as well as probe reactions of cracking of cumene and isomerization of o-xylene.
文摘The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.