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
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
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
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
A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the sampl...A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6+ and Cr^3+ are the catalytic activity center.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
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
ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve...ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N<sub>2</sub> adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h<sup>-1</sup>,and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.展开更多
The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and T...The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and Ti are simultaneously incorporated into V-TiMCM-41 framework.展开更多
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.
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.
基金This work was financially supported by the Sci—ence and Technology Department of Jilin Province,China(20040703—2)and the sub·Program of the Sci—ence and Technology Cooperation Project between China and Spain.
文摘A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6+ and Cr^3+ are the catalytic activity center.
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.
基金Supported by the National Natural Science Foundation of China (20276029) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (20040291005).
文摘ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N<sub>2</sub> adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h<sup>-1</sup>,and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.
文摘The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and Ti are simultaneously incorporated into V-TiMCM-41 framework.