In order to study the production of porous silica compacts by the combustion of rice husk ash (RHA) for tundish lining, the experimental design technique was used to evaluate the effect of firing temperature, soakin...In order to study the production of porous silica compacts by the combustion of rice husk ash (RHA) for tundish lining, the experimental design technique was used to evaluate the effect of firing temperature, soaking time and compaction pressure on controlling both the porosity degree and compressive strength of rice husk ash compacts. The results revealed that while the porosity degree of the compacts decreased with the increase in the entire studied parameters, the compressive strength exhibited another trend especially at a lower soaking time. At a lower soaking time, the increase in firing temperature led to a slight decrease in compressive strength and then increasing thereafter. The porous silica compacts having 30% porosity and 〉 2.5 MPa compressive strength suitable for tundish lining could be obtained from the combustion of rice husk ash compacts.展开更多
Structrue and pore characteristics of the mesoporous silica synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results sho...Structrue and pore characteristics of the mesoporous silica synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results show that mesopores in the sample possess hexagonal arrays obviously, whereas the structure of silica matrix is amorphous. The results also show that the acting mode of silica and CTMA+ inside the mesopores was chemical bonding force. The structure of mesoporous silica was mainly dependent on the aggregational condition of micelle of CTMA+ as well as their liquid-crystallized status. In addition, condensation and dehydration of silicate radicals were accompanied in the process of calcination, which resulted in the mesoporous structure ordered in local range and the pore sizes largening.展开更多
The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-dry...The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-drying (FD),low pressure drying (LPD),high temperature drying (HTD) and chemical modification & ambient drying (CMD) techniques.Observation under pore distribution and structural properties showed that CMD technique leads to homogenous mesoporous silica material with specific surface area of 745 m2/g,and the average pore size around 20 nm,while LPD and HTD result in loosely packed particles with non-isotropic aggregation pattern.The specific surface areas of LPD and HTD samples are 419 and 513 m2/g respectively,and the pore size distribution of the samples are observed distributing widely in range of 10-100 nm.Freeze drying method is a new but prospective way to prepare mesoporous silica.The specific area of FD sample is around 500 m2/g.By the comparison for the properties of the gels,this paper wants to induce a further interest in finding a proper method to synthesize the porous silica gels for low price use.展开更多
Kinetic resolution of DL-phenylalanine methyl ester was carried out using drimobilized α -chymotrypsin (IC) as catalyst. The effects of temperatUre, pH, concentration of substrate and reactionvessels on the resolutio...Kinetic resolution of DL-phenylalanine methyl ester was carried out using drimobilized α -chymotrypsin (IC) as catalyst. The effects of temperatUre, pH, concentration of substrate and reactionvessels on the resolution were investigated. High quality L-phenylalanine was obtained in good yieldby an IC column.展开更多
Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Si05 species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectro...Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Si05 species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption/desorption techniques. EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi2SiO5, which is substantiated by XRD. The UV-Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica. FTIR spectra illustrate the formation of Bi-O-Si linkages in the porous silica framework. SEM and TEM show the spherical morphology, whereas N2 adsorption/desorption study confirms the porosity of the prepared materials. The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa TiO2.展开更多
Porous silica modified with -(CH2)3NH2 (primary amine), -(CH2)3NHCH2CH2NH2 (secondary/primary amine) and -(CH2)3N-cycl-(CH2)4 (tertiary amine) were synthesized by ultrasonic technique under mild conditio...Porous silica modified with -(CH2)3NH2 (primary amine), -(CH2)3NHCH2CH2NH2 (secondary/primary amine) and -(CH2)3N-cycl-(CH2)4 (tertiary amine) were synthesized by ultrasonic technique under mild conditions. The samples were characterized by BET, elemental analysis and TG, showing that the organosilane moieties were grafted onto the surface of porous silica by covalent bond. The structure of the organosilane moieties and ultrasonic treatment time were all significant for the quantities of grafted amino groups. The samples exhibited promising catalytic properties towards the methylation reaction of phenol with dimethyl carbonate (DMC). The methylation reaction with the modified samples featured high selectivity at high conversion. The samples were subjected to utilization for a few recycles without obvious loss of activity to indicate that ultrasonic technique was effective for the preparation of organically modified porous silica catalysts.展开更多
With their hollow morphology and large openings, the as-synthesized porous silica nano-tubes (NTPS), prepared through a sol-gel routine by using nano-sized needle-shaped CaCO3 particles as templates, were used as hos...With their hollow morphology and large openings, the as-synthesized porous silica nano-tubes (NTPS), prepared through a sol-gel routine by using nano-sized needle-shaped CaCO3 particles as templates, were used as host for enzyme immobilization. Bioimmobilization study showed that enzyme molecules could not only be adsorbed on the external surface of NTPS but also entrapped in their inner hollow cores, leading to higher enzyme loading capacities of NTPS (more than 350 mg/g silica) in a shorter time, as compared to common porous silica (less than 50 mg/g) and most conventional mesoporous silica materials (less than 100 mg/g).展开更多
Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance ...Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance to conduct the intracellular trace of nanocarriers.Among many analytical techniques,surface enhanced Raman scattering(SERS)method is one of the current state-of-the-art techniques for cell visualization and trace.In this work,a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose.A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags.The results show that the designed system not only could deliver si RNA into cells for therapy,but also could realize SERS trace with high sensitivity and non-invasive features.The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.展开更多
A sol-gel procedure in a water/oil emulsion was introduced for the synthesis of porous silica spheres. Tetraethoxysilane was used as the silica source. The specific surface area and total pore volume of the product re...A sol-gel procedure in a water/oil emulsion was introduced for the synthesis of porous silica spheres. Tetraethoxysilane was used as the silica source. The specific surface area and total pore volume of the product reached 772.3 m2/g and 0.663 cm3/g, respectively. The electrolyte washing process conferred a surface charge to the product, which displayed self-dispersal properties in water. The porous spheres have potential applications in the fields of drug delivery, controlled release capsules, indoor air pollutant scavengers, and hydrogen storage agents. The oil phase, which accounts for over 8O% of the chemical cost of the procedure, could largely be recycled by filtering, standing, and layering. The whole procedure is suitable for application as an industrial process.展开更多
In this study, we present a facile method to prepare thiocyanato-functionalized porous silica nanospheres. Thiocyanato functionalized silica shells were coated on positively charged cetyltrimethylammonium bromide (C...In this study, we present a facile method to prepare thiocyanato-functionalized porous silica nanospheres. Thiocyanato functionalized silica shells were coated on positively charged cetyltrimethylammonium bromide (CTAB) micelles via hydrolysis and condensation of (3-thiocyanatopropyl)triethoxysilane (TCPTES), the CTAB cores were removed subsequently to form thiocyanato-functionalized porous sil- ica nanospheres. We demonstrate that the contents of the thiocyanato groups within the functionalized porous silica nanosphere frameworks gradually diminished as a function ofhydrothermal treatment time at 100~C until complete removal, confirmed by TGA and FTIR spectra. The data indicate that extended operation at relatively elevated temperatures may lead to the decomposition of the thiocyanato functional groups. In addition, at a lower CTAB concentration (0.0009 M), non-porous thiocyanato functionalized sil- ica nanospheres were formed. However, increasing the CrAB concentration to 0.01 M resulted in porous nanospheres inferring that a CTAB concentration threshold is needed to form thiocyanato-functionalized porous silica nanospheres.展开更多
A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica ...A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica (Mo-M-SiO2) in argon atmosphere at 973 K. Mo-M-SiO2 precursor was facilely obtained via a one-pot synthesis route, using (NH4)6Mo7O24 4H2O (AHM) as molybdenum sources and polymethylhydrosiloxane (PMHS) as silica sources at the initial synthetic step. The optimal C/Mo molar ratio in reaction system for complete carburization of molybdenum species was 7. The carburization process of molybdenum species followed a nontopotactic route involving a MoO2 intermediate phase, which was evidenced by XRD, N2 adsorption-desorption and in situ XPS. Formation mechanism of Mo-M-SiO2 precursor was also proposed by observation of the reaction between AHM and PMHS with TEM. Furthermore, by adding TEOS into silica sources and adjusting TEOS/PMHS mass ratio, crystal phase of molybdenum carbides transferred from β-Mo2C to α-MoC1-x, and SiO2 structure changed from microporous to micro/mesoporous. Catalytic performances of samples were tested using CO hydrogenation as a probe reaction. The supported molybdenum carbides exhibited high selectivity for higher alcohol synthesis compared with bulk β-Mo2C and α-MoC1-x.展开更多
Novel large-sized mesoporous nanofilm-constructed macroporous SiO2(LMNCMS)with two sets of well-defined 3D continuous pass-through macropores(pore size of 0.5-1.0 um,wall thickness of 40-50 nm)was prepared through a d...Novel large-sized mesoporous nanofilm-constructed macroporous SiO2(LMNCMS)with two sets of well-defined 3D continuous pass-through macropores(pore size of 0.5-1.0 um,wall thickness of 40-50 nm)was prepared through a dual-templating approach,and used as an advanced support for TiO2 nanocrystalline photocatalyst.The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts'features and catalytic performance.The photocatalytic activities were evaluated by degradations of methylene blue(MB)and phenol under the simulated sunlight irradiation.To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes,experiments were conducted at wide ranges of the TiO2 loading content,calcination temperature,solution pH,and photocatalyst dosage.Nano-TiO2/LMNCMS exhibited high photocatalytic activity and stability.Rapid matter transport,good access ibility of pollutants to TiO2 and high light harvesting could mainly account for the superior photocatalytic performance.The trapping experiments were performed to identify the main reactive species in the catalytic reactions.展开更多
In this study, novel molecularly imprinted open porous membranes(MIOPMs) were prepared using the Pickering HIPEs template method and molecular imprinting technology for selective adsorption and separation of methyl ...In this study, novel molecularly imprinted open porous membranes(MIOPMs) were prepared using the Pickering HIPEs template method and molecular imprinting technology for selective adsorption and separation of methyl 4-hydroxybenzoate(M4HB). The template M4 HB, functional monomers,crosslinker and plastifier 2-ethylhexyl acrylate(2-EHA) were contained in the oil phase. Hydrophobic silica nanoparticles(HNP-SiO2) were employed as a stabilizer to establish stable W/O Pickering HIPEs with nonionic surfactant sorbitantrioleate(Span 85). The results of SEM and FTIR indicated that the optimal MIOPMs were prepared successfully and possessed open and interconnecting pores. Then, the MIOPMs were used as sorbents for M4 HB. The correlation coefficient(R^2) values for the Langmuir–Freundlich isotherm model and pseudo-second-order kinetic model fitting to the adsorption equilibrium and kinetic data respectively were all higher than 0.95. The maximum adsorption capacity and the time of rapid adsorption for MIOPM4 were 4.146 mg g^-1 and 100 min, respectively. In addition, the permeability separation factor of MIOPMs for M4 HB compared to a structurally related analog methyl2-hydroxybenzoate(M2HB) could reach 3.122.展开更多
Pd-based egg-shell nano-catalysts were prepared using porous hollow silica nanoparticles (PHSNs) as support, and the as-prepared catalysts were modified with TiO2 to promote their selectivity for hydro-genation of a...Pd-based egg-shell nano-catalysts were prepared using porous hollow silica nanoparticles (PHSNs) as support, and the as-prepared catalysts were modified with TiO2 to promote their selectivity for hydro-genation of acetylene. Pd nanoparticles were loaded evenly on PHSNs and TiO2 was loaded on the active Pd particles. The effects of reduction time and temperature and the amount of TiO2 added on catalytic per-formances were investigated by using a fixed-bed micro-reactor. It was found that the catalysts showed better performance when reduced at 300 ℃ than at 500℃, and if reduced for 1 h than 3 h. When the amount of Ti added was 6 times that of Pd, the catalyst showed the highest ethylene selectivity.展开更多
文摘In order to study the production of porous silica compacts by the combustion of rice husk ash (RHA) for tundish lining, the experimental design technique was used to evaluate the effect of firing temperature, soaking time and compaction pressure on controlling both the porosity degree and compressive strength of rice husk ash compacts. The results revealed that while the porosity degree of the compacts decreased with the increase in the entire studied parameters, the compressive strength exhibited another trend especially at a lower soaking time. At a lower soaking time, the increase in firing temperature led to a slight decrease in compressive strength and then increasing thereafter. The porous silica compacts having 30% porosity and 〉 2.5 MPa compressive strength suitable for tundish lining could be obtained from the combustion of rice husk ash compacts.
基金FundedbytheNationalNaturalScienceFoundationofChi na (5 0 2 72 0 4 8)andtheNaturalScienceFoundationofHubeiProv ince (2 0 0 1ABB0 76 )
文摘Structrue and pore characteristics of the mesoporous silica synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results show that mesopores in the sample possess hexagonal arrays obviously, whereas the structure of silica matrix is amorphous. The results also show that the acting mode of silica and CTMA+ inside the mesopores was chemical bonding force. The structure of mesoporous silica was mainly dependent on the aggregational condition of micelle of CTMA+ as well as their liquid-crystallized status. In addition, condensation and dehydration of silicate radicals were accompanied in the process of calcination, which resulted in the mesoporous structure ordered in local range and the pore sizes largening.
基金Sponsored by the National Mega-Project of Scientific & Technical Supporting Programs,Ministry of Science &Technology of China (Grant No.2006BAJ04A04)the Science Foundation of Liaoning Province,China (Grant No. 2008S190)
文摘The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-drying (FD),low pressure drying (LPD),high temperature drying (HTD) and chemical modification & ambient drying (CMD) techniques.Observation under pore distribution and structural properties showed that CMD technique leads to homogenous mesoporous silica material with specific surface area of 745 m2/g,and the average pore size around 20 nm,while LPD and HTD result in loosely packed particles with non-isotropic aggregation pattern.The specific surface areas of LPD and HTD samples are 419 and 513 m2/g respectively,and the pore size distribution of the samples are observed distributing widely in range of 10-100 nm.Freeze drying method is a new but prospective way to prepare mesoporous silica.The specific area of FD sample is around 500 m2/g.By the comparison for the properties of the gels,this paper wants to induce a further interest in finding a proper method to synthesize the porous silica gels for low price use.
文摘Kinetic resolution of DL-phenylalanine methyl ester was carried out using drimobilized α -chymotrypsin (IC) as catalyst. The effects of temperatUre, pH, concentration of substrate and reactionvessels on the resolution were investigated. High quality L-phenylalanine was obtained in good yieldby an IC column.
基金PAKR and MS thank CSIR,New Delhi for funding this work under Emeritus Scientist Scheme
文摘Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Si05 species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption/desorption techniques. EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi2SiO5, which is substantiated by XRD. The UV-Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica. FTIR spectra illustrate the formation of Bi-O-Si linkages in the porous silica framework. SEM and TEM show the spherical morphology, whereas N2 adsorption/desorption study confirms the porosity of the prepared materials. The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa TiO2.
文摘Porous silica modified with -(CH2)3NH2 (primary amine), -(CH2)3NHCH2CH2NH2 (secondary/primary amine) and -(CH2)3N-cycl-(CH2)4 (tertiary amine) were synthesized by ultrasonic technique under mild conditions. The samples were characterized by BET, elemental analysis and TG, showing that the organosilane moieties were grafted onto the surface of porous silica by covalent bond. The structure of the organosilane moieties and ultrasonic treatment time were all significant for the quantities of grafted amino groups. The samples exhibited promising catalytic properties towards the methylation reaction of phenol with dimethyl carbonate (DMC). The methylation reaction with the modified samples featured high selectivity at high conversion. The samples were subjected to utilization for a few recycles without obvious loss of activity to indicate that ultrasonic technique was effective for the preparation of organically modified porous silica catalysts.
文摘With their hollow morphology and large openings, the as-synthesized porous silica nano-tubes (NTPS), prepared through a sol-gel routine by using nano-sized needle-shaped CaCO3 particles as templates, were used as host for enzyme immobilization. Bioimmobilization study showed that enzyme molecules could not only be adsorbed on the external surface of NTPS but also entrapped in their inner hollow cores, leading to higher enzyme loading capacities of NTPS (more than 350 mg/g silica) in a shorter time, as compared to common porous silica (less than 50 mg/g) and most conventional mesoporous silica materials (less than 100 mg/g).
基金financially supported by the Australian Research Council(ARC)Discovery Projects(Nos.DP140104062 and DP160104866)Fundamental Research Funds for the Central Universities(Nos.FRF-TP-19-017B1,2302015-06500017,FRF-BR-19-003B,FRF-BD-20-14A)National Natural Science Foundation of China(No.21501009)。
文摘Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance to conduct the intracellular trace of nanocarriers.Among many analytical techniques,surface enhanced Raman scattering(SERS)method is one of the current state-of-the-art techniques for cell visualization and trace.In this work,a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose.A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags.The results show that the designed system not only could deliver si RNA into cells for therapy,but also could realize SERS trace with high sensitivity and non-invasive features.The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.
基金supported by the Key Project of the National Eleventh Five-Year Research Program of China(2008BAE66B00)by the Scientific and Technological Planning Project of JilinProvince(200,75,009)
文摘A sol-gel procedure in a water/oil emulsion was introduced for the synthesis of porous silica spheres. Tetraethoxysilane was used as the silica source. The specific surface area and total pore volume of the product reached 772.3 m2/g and 0.663 cm3/g, respectively. The electrolyte washing process conferred a surface charge to the product, which displayed self-dispersal properties in water. The porous spheres have potential applications in the fields of drug delivery, controlled release capsules, indoor air pollutant scavengers, and hydrogen storage agents. The oil phase, which accounts for over 8O% of the chemical cost of the procedure, could largely be recycled by filtering, standing, and layering. The whole procedure is suitable for application as an industrial process.
文摘In this study, we present a facile method to prepare thiocyanato-functionalized porous silica nanospheres. Thiocyanato functionalized silica shells were coated on positively charged cetyltrimethylammonium bromide (CTAB) micelles via hydrolysis and condensation of (3-thiocyanatopropyl)triethoxysilane (TCPTES), the CTAB cores were removed subsequently to form thiocyanato-functionalized porous sil- ica nanospheres. We demonstrate that the contents of the thiocyanato groups within the functionalized porous silica nanosphere frameworks gradually diminished as a function ofhydrothermal treatment time at 100~C until complete removal, confirmed by TGA and FTIR spectra. The data indicate that extended operation at relatively elevated temperatures may lead to the decomposition of the thiocyanato functional groups. In addition, at a lower CTAB concentration (0.0009 M), non-porous thiocyanato functionalized sil- ica nanospheres were formed. However, increasing the CrAB concentration to 0.01 M resulted in porous nanospheres inferring that a CTAB concentration threshold is needed to form thiocyanato-functionalized porous silica nanospheres.
基金supported by the National Natural Science Foundation of China (No. 200573128)the Natural Science Foundation of Shanxi Province, China (No. 20051025)the Natural Science Foundation for Young Scientists of Shanxi Province, China (No. 2006021031)
文摘A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica (Mo-M-SiO2) in argon atmosphere at 973 K. Mo-M-SiO2 precursor was facilely obtained via a one-pot synthesis route, using (NH4)6Mo7O24 4H2O (AHM) as molybdenum sources and polymethylhydrosiloxane (PMHS) as silica sources at the initial synthetic step. The optimal C/Mo molar ratio in reaction system for complete carburization of molybdenum species was 7. The carburization process of molybdenum species followed a nontopotactic route involving a MoO2 intermediate phase, which was evidenced by XRD, N2 adsorption-desorption and in situ XPS. Formation mechanism of Mo-M-SiO2 precursor was also proposed by observation of the reaction between AHM and PMHS with TEM. Furthermore, by adding TEOS into silica sources and adjusting TEOS/PMHS mass ratio, crystal phase of molybdenum carbides transferred from β-Mo2C to α-MoC1-x, and SiO2 structure changed from microporous to micro/mesoporous. Catalytic performances of samples were tested using CO hydrogenation as a probe reaction. The supported molybdenum carbides exhibited high selectivity for higher alcohol synthesis compared with bulk β-Mo2C and α-MoC1-x.
基金This work was financially supported by the Science and Technology Benefiting Projects of Ningbo(Grant No.2017C50033),the Public Projects of Zhejiang Province(Grant No.LGG19E020002),and the KC Wong Happiness Fund in Ningbo University.
文摘Novel large-sized mesoporous nanofilm-constructed macroporous SiO2(LMNCMS)with two sets of well-defined 3D continuous pass-through macropores(pore size of 0.5-1.0 um,wall thickness of 40-50 nm)was prepared through a dual-templating approach,and used as an advanced support for TiO2 nanocrystalline photocatalyst.The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts'features and catalytic performance.The photocatalytic activities were evaluated by degradations of methylene blue(MB)and phenol under the simulated sunlight irradiation.To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes,experiments were conducted at wide ranges of the TiO2 loading content,calcination temperature,solution pH,and photocatalyst dosage.Nano-TiO2/LMNCMS exhibited high photocatalytic activity and stability.Rapid matter transport,good access ibility of pollutants to TiO2 and high light harvesting could mainly account for the superior photocatalytic performance.The trapping experiments were performed to identify the main reactive species in the catalytic reactions.
基金financially supported by the National Natural Science Foundation of China(Nos.21406085,21207051)
文摘In this study, novel molecularly imprinted open porous membranes(MIOPMs) were prepared using the Pickering HIPEs template method and molecular imprinting technology for selective adsorption and separation of methyl 4-hydroxybenzoate(M4HB). The template M4 HB, functional monomers,crosslinker and plastifier 2-ethylhexyl acrylate(2-EHA) were contained in the oil phase. Hydrophobic silica nanoparticles(HNP-SiO2) were employed as a stabilizer to establish stable W/O Pickering HIPEs with nonionic surfactant sorbitantrioleate(Span 85). The results of SEM and FTIR indicated that the optimal MIOPMs were prepared successfully and possessed open and interconnecting pores. Then, the MIOPMs were used as sorbents for M4 HB. The correlation coefficient(R^2) values for the Langmuir–Freundlich isotherm model and pseudo-second-order kinetic model fitting to the adsorption equilibrium and kinetic data respectively were all higher than 0.95. The maximum adsorption capacity and the time of rapid adsorption for MIOPM4 were 4.146 mg g^-1 and 100 min, respectively. In addition, the permeability separation factor of MIOPMs for M4 HB compared to a structurally related analog methyl2-hydroxybenzoate(M2HB) could reach 3.122.
基金the financial support provided by National Natural Science Foundation of China (Nos.20821004 and 50642042)the Key Research Program of Ministry ofEducation of China (No. 108009)+1 种基金CNPC Innovation Foundation (No.06-04D-01-01-02)the Chinese Universities Scientific Fund
文摘Pd-based egg-shell nano-catalysts were prepared using porous hollow silica nanoparticles (PHSNs) as support, and the as-prepared catalysts were modified with TiO2 to promote their selectivity for hydro-genation of acetylene. Pd nanoparticles were loaded evenly on PHSNs and TiO2 was loaded on the active Pd particles. The effects of reduction time and temperature and the amount of TiO2 added on catalytic per-formances were investigated by using a fixed-bed micro-reactor. It was found that the catalysts showed better performance when reduced at 300 ℃ than at 500℃, and if reduced for 1 h than 3 h. When the amount of Ti added was 6 times that of Pd, the catalyst showed the highest ethylene selectivity.