The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out....The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out. High conversion （≥98%） and specific selectivity were obtained using the novel carbon based acid, which kept high activity after it was reused 5 times. Moreover. the catalyst could be used to catalyze the acetalization and ketalization of different aldehydes and ketones with superior yield. The yield of several products was over 90%. The novel heterogeneous catalyst has the distinct advantages of high activity, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the success of the green process greatly.展开更多
Nowadays, many kinds of software, which have succes sf ully created the integration of CAD, CAPP and CAM, find their disadvantages in p ractical manufacturing. As a result, it is welcomed to develop small CAD/CAPP sy ...Nowadays, many kinds of software, which have succes sf ully created the integration of CAD, CAPP and CAM, find their disadvantages in p ractical manufacturing. As a result, it is welcomed to develop small CAD/CAPP sy stems on a proper CAD platform, which aim at requirements of factories. Based on the one of the most popular three-dimensional design software SolidWorks, we successfully developed a set of gear pump CAD /CAPP software for Huaiyin Gene ral Factory of Mechanics. 1 The architecture and function of the software According to the need of the enterprises, the general structure of the software contain two subsystems, which are detailed as follows: · The gear pump CAD subsystem contains four main modules, including the optiona l design module of gear pump, module of part design, the module of entity modeli ng and the module of drawing which creates 2 D drawings of parts and assembly c orresponding 3 D modals. · The gear pump CAPP subsystem, which is a combination of creative mode and der ivate mode, also includes four modules, they are the module of access to feature s, the module of planning process route, the module of designing process sheets and the module of generating process documents. 2 The developing environment of the system Basing on Windows 98 and SolidWorks2001 platform, this system creates all functi ons by using Visual C++ 6.0 as developing tools. 3 The keys to the CAD/CAPP integration 3.1 The establishment of product information modal The information of parts is the basis of process planning. In this system, we us e feature modeling to describe the information of parts and assembly of gear pum p, and set up a fundamental basis for the whole system. The information module o f gear pump includes the information of both the assembly and the parts; the par t-describing module uses four-layer structure that is subassembly layer, part layer, feature layer and geometric layer. 3.2 The operation of the information on feature modeling After establishment of information mode of gear pump, the next key problem is ho w to transmit information of product to CAPP subsystem. In order to integrate pe rfectly, connecting CAD with CAPP directly can be a good method. In this system, all information of parts is store in the part drawing files, and the CAPP syste m can load these files to get information. The gear pumps, which are produced by Huaiyin General Factory of Mechanics, are usually belong to several similar typ es, and this means that most products possess large number of similar feature. T herefore, we can easily establish a specific feature for gear pump CAD/CAPP syst em. All parts are created by selecting these features and/or adding few special features. In the module of access to feature of CAPP subsystem, the main task is to find the features and the information will be easily got. 4 Conclusion This system successfully creates gear pump CAD/CAPP integration based on SolidWo rks. 3D CAD software provide more convenient platform for integration and will i nevitably become the mainstream of product design. By developing this system, we clearly realize the promising future of SolidWorks.展开更多
The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid ...The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid spin NOON state is investigated. Based on the tunable effective coupling coefficient, we propose a generation scheme of the three-spin NOON state, i.e, the Creenberger-Horne-Zeilinger （CHZ） state, and discussed the mea- surement resolution reduction due to decoherence. It is unnecessary to entangle spins as many as possible when decoherence exists. In practice, defect spins in diamond and alp donors with long coherence time can be applied with current techniques in the nano-scaled high resolution magnetic measurement.展开更多
Solid strong base catalysts are highly attractive for diverse reactions owing to their advantages of neglectable corrosion,facile separation,and environmental friendliness.However,their widespread applications are imp...Solid strong base catalysts are highly attractive for diverse reactions owing to their advantages of neglectable corrosion,facile separation,and environmental friendliness.However,their widespread applications are impeded by basic components aggregation and low stability.In this work,we fabricate single calcium atoms on graphene(denoted as Ca1/G)by use of a redox strategy for the first time,producing solid strong base catalyst with high activity and stability.The precursor Ca(NO_(3))_(2)is first reduced to CaO at 400℃ by the support graphene,forming CaO/G with conventional basic sites,and the subsequent reduction at 850℃results in the generation of Ca1/G with atomically dispersed Ca.Various characterizations reveal that Ca single atoms are anchored on graphene in tetra-coordination(Ca-C_(2)-N_(2))where N is in situ doped from Ca(NO_(3))_(2).The atomically dispersed Ca,along with their anchoring on the support,endow Ca1/G with high activity and stability toward the transesterification reaction of ethylene carbonate with methanol.The turnover frequency value reaches 128.0 h^(-1)on Ca1/G,which is much higher than the traditional counterpart CaO/G and various reported solid strong bases(2.9-46.2 h^(-1)).Moreover,the activity of Ca1/G is well maintained during 5 cycles,while 60%of activity is lost for the conventional analogue CaO/G due to the leaching of Ca.展开更多
We demonstrate eftlcient generation of continuous spectrum centered at 40Ohm from solid thin plates. By frequency doubling of 0.8m J, 3Ors Ti：sapphire laser pulses with a BBO crystal, 0.2m J, 33fs laser pulses at 400...We demonstrate eftlcient generation of continuous spectrum centered at 40Ohm from solid thin plates. By frequency doubling of 0.8m J, 3Ors Ti：sapphire laser pulses with a BBO crystal, 0.2m J, 33fs laser pulses at 400nm are generated. Focusing the 400-nm pulses into 7 thin fused silica plates, we obtain 0.15mJ continuous spectrum covering 350-450 nm. After compressing by 3 pairs of chirped mirrors, 0. 12 m J, 8.6 fs pulses are achieved. To the best of our knowledge, this is the first time that sub-10-fs pulses centered at 400nm are generated by solid thin plates, which shows that spectral broadening in solid-state materials works not only at 800nm but also at different wavelengths.展开更多
All-solid-state lithium metal batteries(ASSLMBs)are emerging as a groundbreaking solution,offering higher energy and power densities along with improved safety compared to conventional lithium-ion systems.However,crit...All-solid-state lithium metal batteries(ASSLMBs)are emerging as a groundbreaking solution,offering higher energy and power densities along with improved safety compared to conventional lithium-ion systems.However,critical challenges remain-particularly the instability at the interface between solid-state electrolytes(SSEs)and lithium metal,and the growth of lithium dendrites.展开更多
Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-a...Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.展开更多
Biodiesel industrial production based on a solid base catalyst in a fixed-bed was simulated. The lab and bench scale experiments were carded out effectively, in which the kinetic model is established and it can descri...Biodiesel industrial production based on a solid base catalyst in a fixed-bed was simulated. The lab and bench scale experiments were carded out effectively, in which the kinetic model is established and it can describe the transesterification reaction well. The Antoine equation of biodiesel is regressed with the vapor-liquid data cited of literature. The non-random two liquid （NRTL） model is applied to describe the system of fatty acid methyl ester （FAME）, methanol and glycerol and parameters are obtained. The Ternary phase map is obtained from Aspen Plus via the liquid-liquid equilibrium （LLE） data. In order to describe the production in a fixed-bed performs in industrial scale after being magnified 1 000 times, the Aspen Plus simulation is employed, where two flowsheets are simulated to predict material and energy consumption. The simulation results prove that at least 350. 42 kW energy consumption can be reduced per hour to produce per ton biodiesel compared with data reported in previous references.展开更多
Composite solid base catalysts derived from Ca‐M‐Al(M=Mg,La,Ce,Y)layered double hydroxides(LDH)were synthesized,characterized and applied to the transesterification of methanol with propylene carbonate.X‐ray diffra...Composite solid base catalysts derived from Ca‐M‐Al(M=Mg,La,Ce,Y)layered double hydroxides(LDH)were synthesized,characterized and applied to the transesterification of methanol with propylene carbonate.X‐ray diffraction analyses of the catalysts show that all of the catalysts were in the form of composite oxides.Compared with the Ca‐Al LDH catalyst,the specific surface areas and pore volumes of the catalysts were increased with the introduction of Mg,La or Ce.The catalytic performance of these catalysts increases in the order of Ca‐Y‐Al<Ca‐Al<Ca‐Ce‐Al<Ca‐La‐Al<Ca‐Mg‐Al,which is consistent with the total surface basic amounts of these materials and the formation of especially strong basic sites following modification with Mg and La.The Ca‐Mg‐Al catalyst shows the highest(Ca+Mg):Al atomic ratio,indicating that it likely contains more unsaturated O2?ions,providing it with the highest concentration of very strong basic sites.The recyclability of these catalysts is improved following the addition of Mg,La,Ce or Y,with the Ca‐Mg‐Al maintaining a high level of activity after ten recycling trials.X‐ray diffraction analyses of fresh and used Ca‐Mg‐Al demonstrate that this catalyst is exceptionally stable,which could be of value in practical applications related to heterogeneous catalysis.展开更多
Dispersion of KF on AlPO4-5 molecular sieve created basic sites and caused 1654 cm- band of bidentate carbonate in CO2 adsorption.After pre-treated above 823K. 5%KF/AlPO4-5exhibited basic catalytic activity in the iso...Dispersion of KF on AlPO4-5 molecular sieve created basic sites and caused 1654 cm- band of bidentate carbonate in CO2 adsorption.After pre-treated above 823K. 5%KF/AlPO4-5exhibited basic catalytic activity in the isomerization of butenes at 273K. and the activity increasedwith the pre-treatment temperature up to 923K.展开更多
The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 C and atmospheric pressure.The KOH/mordenite processed transesterifi...The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 C and atmospheric pressure.The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of96.7%under optimum conditions,while a methyl ester content over 94.5%was obtained in the packed-bed reactor.This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor.Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts.Leaching of the potassium species was negligible,whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.展开更多
One-pot synthesis of Mg containing MCM-41(Mg-MCM-41) materials was respectively carried out by a room temperature(RT) method and a hydrothermal(HT) method for aldol condensation of 4-nitrobenzaldehyde and acetone and ...One-pot synthesis of Mg containing MCM-41(Mg-MCM-41) materials was respectively carried out by a room temperature(RT) method and a hydrothermal(HT) method for aldol condensation of 4-nitrobenzaldehyde and acetone and self-condensation of acetone. The RT method can prepare MCM-41 materials containing large amounts of Mg while maintaining the structural characteristics of MCM-41 even at very low Si/Mg ratios(large Mg loadings), but the HT method cannot. The RT method can also give more active catalysts than the HT method, because the catalysts prepared by the RT method are more basic than those prepared by the HT one. The characterization indicates that Mg atoms in the Mg-MCM-41 prepared by the RT method exist as MgO disperses well on the wall surface of pores, while those in Mg-MCM-41 prepared by the HT method are included in the bulk with a smectite-like structure.展开更多
MgO/Al2O3 and Fe2O3/MgO/Al2O3 solid bases were prepared through mixing method. After sulfonated cobalt phthalocyanine （CoPcS） being supported on these solid bases, the catalytic performance of these catalysts was ev...MgO/Al2O3 and Fe2O3/MgO/Al2O3 solid bases were prepared through mixing method. After sulfonated cobalt phthalocyanine （CoPcS） being supported on these solid bases, the catalytic performance of these catalysts was evaluated by means of mercaptan oxidation reaction. The samples were characterized by X-ray diffraction （XRD）, CO2 temperature-programmed desorption （CO2-TPD）, FTIR spectroscopy, and X-ray photoelectron spectroscopy （XPS）. Investigation was focused on the effect of Fe2O3 on activity, crystal structure, basicity, and stability of the catalyst and also on the role of Fe2O3 in the mercaptan oxidation processes. Test results have shown that the Fe2O3/MgO/Al2O3- CoPcS catalyst has a higher initial activity and a much longer service life than the MgO/Al2O3-CoPcS catalyst. The increased types of basic sites coupled with an enhanced oxidation ability resulted from the addition of Fe2O3 have contributed to the improvement of the catalytic activity of the MgO/Al2O3-CoPcS catalyst.展开更多
For the development of fiber optics for the range from 0.2 to 50.0 μm, one needs light-stable, nonhygroscopic, ductile crystals that would be transparent within this spectral range and have a lack of cleavage, and fr...For the development of fiber optics for the range from 0.2 to 50.0 μm, one needs light-stable, nonhygroscopic, ductile crystals that would be transparent within this spectral range and have a lack of cleavage, and from which the flexible infrared （IR） fibers are extruded. The crystals based on solid solutions of silver and monadic thallium haides meet the conditions listed above. Consequently, by differential thermal and x ray analyses, we study the TIBr-TII phase diagram using the crystals with optimal compositions, which we grow ourselves. We also manu- facture light-stable nanocrystalline IR fibers that are transparent at longer wavelengths compared with AgC1-AgBr fibers.展开更多
A new reaction system was designed to economically convert glucose to lactic acid environment-friendly. Hydrophobic ionic liquids were chosen as solvent that can promote the decomposition reaction of glucose, and the ...A new reaction system was designed to economically convert glucose to lactic acid environment-friendly. Hydrophobic ionic liquids were chosen as solvent that can promote the decomposition reaction of glucose, and the catalytic performance of the solid bases was evaluated. Both the reaction temperature and time can affect the yield of lactic acid. A high yield （97%） of lactic acid was achieved under the optimal reaction condition. The IH NMR spectra and HPLC-MS were used to identify the formation of the lactic acid and variations of ionic liquid. It is found that ionic-liquids have a unique solvent effect for glucose and bases. Water can be used as solvent to extract calcium lactate. This shows a great potential of hydrophobic ionic liquids in the solid bases catalyzed reaction that is limited by the weak solubility of solid bases in organic and water solution.展开更多
An automatic visible spectrometer based on a non-collinear acousto-optic tunable filter (AOTF) is constructed for high-speed spectrometry. Its spectral filtering characteristics, such as relationships between the radi...An automatic visible spectrometer based on a non-collinear acousto-optic tunable filter (AOTF) is constructed for high-speed spectrometry. Its spectral filtering characteristics, such as relationships between the radio-frequency (RF) driving frequency and the output central wavelength, the output bandwidth and the central wavelength, its typical spectral point spread function (PSF), and so on, are studied systematically. The preliminary measurement results of AOTF spectrometer show that it is a solid-state, high-speed, easily controllable by computer-programming, rugged and compact spectroscopic device in comparison with a conventional grating spectrometer, and has the potential for widespread spectrometric applications.展开更多
Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results revea...Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.展开更多
A rapid and environmentally friendly approach to synthesize hierarchical sodalite from natural aluminosilicate mineral without the involvement of any mesoporogen or post-synthesis treatment was developed.This strategy...A rapid and environmentally friendly approach to synthesize hierarchical sodalite from natural aluminosilicate mineral without the involvement of any mesoporogen or post-synthesis treatment was developed.This strategy involves three important steps:the first is the depolymerization of an aluminosilicate mineral into highly reactive silicon and aluminum species with ideal meso-scale structures through activation of a sub-molten salt.The second step is the hydrolysis and condensation of the activated aluminosilicate mineral into zeolitic precursors that also have a meso-scale structure.The third is the rapid zeolitization of the zeolitic precursors through the reversed crystal growth route at room temperature and ambient pressure to form hierarchical sodalite.The physicochemical properties of the as-synthesized sodalite were systematically characterized,and the formation mechanism of the hierarchical pore structure was discussed.When used as a solid base catalyst for Knoevenagel condensation,the as-synthesized sodalite and its potassium ion-exchanged product with hierarchical micro-meso-macroporous structure both exhibited high catalytic activity and product selectivity.展开更多
A facile route for the synthesis of dimethyl adipate （DAP） from cyclopentanone and dimethyl carbonate （DMC） in the pres- ence of solid base catalysts has been developed. It was found that the intermediate carbomet...A facile route for the synthesis of dimethyl adipate （DAP） from cyclopentanone and dimethyl carbonate （DMC） in the pres- ence of solid base catalysts has been developed. It was found that the intermediate carbomethoxycyclopentanone （CMCP） was produced from cyclopentanone with DMC in the first step, and then CMCP was further converted to DAP by reacting with a methoxide group. The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the a-position by base sites, and solid bases with moderate strength, such as MgO, favor the formation of DAP.展开更多
Ordered porous solid strong bases(OPSSBs)have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions.The main obstacle for fabricating OPSSBs is the requirem...Ordered porous solid strong bases(OPSSBs)have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions.The main obstacle for fabricating OPSSBs is the requirement of high temperature to produce strong basicity on ordered porous materials.For example,the temperatures of 600-650℃ are required for the decomposition of base precursor NaNO_(3)to basic sites on mesoporous silica SBA-15 and zeolite Y.Such high decomposition temperatures are energy-intensive and harmful to the structure of supports.Herein,we report the fabrication of OPSSBs by utilizing the redox interaction between base precursor and low-valence metal centers(e.g.,Cr^(3+))in metal-organic frameworks(MOFs).The base precursor NaNO_(3)on MIL-101(Cr)can be converted to basic sites entirely at 300℃,which is quite lower than those of the conventional thermal conversion on SBA-15 and zeolite Y(600-650℃).The exploration on decomposition mechanism reveals that the valence change of Cr^(3+)to Cr^(6+)takes place during the conversion of NaNO_(3)to basic sites.In this way,MOFs-derived base catalysts have been synthesized successfully by the host-vip redox strategy and exhibit high catalytic activity in typical base-catalyzed reactions.展开更多
基金the National Key Project ofScientific and Technical SupportingPrograms Funded by the Ministry of Science & Technology of China (No.2006BAE03B06)the Shanghai International Cooperation of Science and Technology Project (No.06SR07101).
文摘The synthesis of 2, 4-diisopropyl-5,5-dimethy1- 1.3-dioxane through the acetalization of isobutyraldehyde with 2, 2, 4-trimethy1-1,3-pentanediol （TMPD） catalyzed by the novel carbon based acid was first carried out. High conversion （≥98%） and specific selectivity were obtained using the novel carbon based acid, which kept high activity after it was reused 5 times. Moreover. the catalyst could be used to catalyze the acetalization and ketalization of different aldehydes and ketones with superior yield. The yield of several products was over 90%. The novel heterogeneous catalyst has the distinct advantages of high activity, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the success of the green process greatly.
文摘Nowadays, many kinds of software, which have succes sf ully created the integration of CAD, CAPP and CAM, find their disadvantages in p ractical manufacturing. As a result, it is welcomed to develop small CAD/CAPP sy stems on a proper CAD platform, which aim at requirements of factories. Based on the one of the most popular three-dimensional design software SolidWorks, we successfully developed a set of gear pump CAD /CAPP software for Huaiyin Gene ral Factory of Mechanics. 1 The architecture and function of the software According to the need of the enterprises, the general structure of the software contain two subsystems, which are detailed as follows: · The gear pump CAD subsystem contains four main modules, including the optiona l design module of gear pump, module of part design, the module of entity modeli ng and the module of drawing which creates 2 D drawings of parts and assembly c orresponding 3 D modals. · The gear pump CAPP subsystem, which is a combination of creative mode and der ivate mode, also includes four modules, they are the module of access to feature s, the module of planning process route, the module of designing process sheets and the module of generating process documents. 2 The developing environment of the system Basing on Windows 98 and SolidWorks2001 platform, this system creates all functi ons by using Visual C++ 6.0 as developing tools. 3 The keys to the CAD/CAPP integration 3.1 The establishment of product information modal The information of parts is the basis of process planning. In this system, we us e feature modeling to describe the information of parts and assembly of gear pum p, and set up a fundamental basis for the whole system. The information module o f gear pump includes the information of both the assembly and the parts; the par t-describing module uses four-layer structure that is subassembly layer, part layer, feature layer and geometric layer. 3.2 The operation of the information on feature modeling After establishment of information mode of gear pump, the next key problem is ho w to transmit information of product to CAPP subsystem. In order to integrate pe rfectly, connecting CAD with CAPP directly can be a good method. In this system, all information of parts is store in the part drawing files, and the CAPP syste m can load these files to get information. The gear pumps, which are produced by Huaiyin General Factory of Mechanics, are usually belong to several similar typ es, and this means that most products possess large number of similar feature. T herefore, we can easily establish a specific feature for gear pump CAD/CAPP syst em. All parts are created by selecting these features and/or adding few special features. In the module of access to feature of CAPP subsystem, the main task is to find the features and the information will be easily got. 4 Conclusion This system successfully creates gear pump CAD/CAPP integration based on SolidWo rks. 3D CAD software provide more convenient platform for integration and will i nevitably become the mainstream of product design. By developing this system, we clearly realize the promising future of SolidWorks.
基金Supported by the National Basic Research Program of China(No 2011CB921200)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant (No XDB01030200)+1 种基金the National Natural Science Foundation of China(No11374290)the Fundamental Research Funds for the Central Universities and the Foundation for Authors of National Excellent Doctoral Dissertation of China
文摘The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid spin NOON state is investigated. Based on the tunable effective coupling coefficient, we propose a generation scheme of the three-spin NOON state, i.e, the Creenberger-Horne-Zeilinger （CHZ） state, and discussed the mea- surement resolution reduction due to decoherence. It is unnecessary to entangle spins as many as possible when decoherence exists. In practice, defect spins in diamond and alp donors with long coherence time can be applied with current techniques in the nano-scaled high resolution magnetic measurement.
基金supported by the National Science Fund for Distinguished Young Scholars(22125804)the National Natural Science Foundation of China(22078155 and 22178163)the National Students'platform for innovation and entrepreneurship training program(20210291013Z).
文摘Solid strong base catalysts are highly attractive for diverse reactions owing to their advantages of neglectable corrosion,facile separation,and environmental friendliness.However,their widespread applications are impeded by basic components aggregation and low stability.In this work,we fabricate single calcium atoms on graphene(denoted as Ca1/G)by use of a redox strategy for the first time,producing solid strong base catalyst with high activity and stability.The precursor Ca(NO_(3))_(2)is first reduced to CaO at 400℃ by the support graphene,forming CaO/G with conventional basic sites,and the subsequent reduction at 850℃results in the generation of Ca1/G with atomically dispersed Ca.Various characterizations reveal that Ca single atoms are anchored on graphene in tetra-coordination(Ca-C_(2)-N_(2))where N is in situ doped from Ca(NO_(3))_(2).The atomically dispersed Ca,along with their anchoring on the support,endow Ca1/G with high activity and stability toward the transesterification reaction of ethylene carbonate with methanol.The turnover frequency value reaches 128.0 h^(-1)on Ca1/G,which is much higher than the traditional counterpart CaO/G and various reported solid strong bases(2.9-46.2 h^(-1)).Moreover,the activity of Ca1/G is well maintained during 5 cycles,while 60%of activity is lost for the conventional analogue CaO/G due to the leaching of Ca.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11434016,11574384 and 11674386the National Key Basic Research Program of China under Grant Nos 2013CB922401 and 2013CB922402
文摘We demonstrate eftlcient generation of continuous spectrum centered at 40Ohm from solid thin plates. By frequency doubling of 0.8m J, 3Ors Ti：sapphire laser pulses with a BBO crystal, 0.2m J, 33fs laser pulses at 400nm are generated. Focusing the 400-nm pulses into 7 thin fused silica plates, we obtain 0.15mJ continuous spectrum covering 350-450 nm. After compressing by 3 pairs of chirped mirrors, 0. 12 m J, 8.6 fs pulses are achieved. To the best of our knowledge, this is the first time that sub-10-fs pulses centered at 400nm are generated by solid thin plates, which shows that spectral broadening in solid-state materials works not only at 800nm but also at different wavelengths.
文摘All-solid-state lithium metal batteries(ASSLMBs)are emerging as a groundbreaking solution,offering higher energy and power densities along with improved safety compared to conventional lithium-ion systems.However,critical challenges remain-particularly the instability at the interface between solid-state electrolytes(SSEs)and lithium metal,and the growth of lithium dendrites.
基金supported by the National Natural Science Foundation of China(22279028,22179018)the Natural Science Foundation of Hebei Province(B2021205019)the 333 Project of Hebei Province(C20231106).
文摘Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.
基金The National Basic Research Program of China(973Program)(No.2010CB732206)the National Natural Science Foundation of China(No.21076044,21276050)
文摘Biodiesel industrial production based on a solid base catalyst in a fixed-bed was simulated. The lab and bench scale experiments were carded out effectively, in which the kinetic model is established and it can describe the transesterification reaction well. The Antoine equation of biodiesel is regressed with the vapor-liquid data cited of literature. The non-random two liquid （NRTL） model is applied to describe the system of fatty acid methyl ester （FAME）, methanol and glycerol and parameters are obtained. The Ternary phase map is obtained from Aspen Plus via the liquid-liquid equilibrium （LLE） data. In order to describe the production in a fixed-bed performs in industrial scale after being magnified 1 000 times, the Aspen Plus simulation is employed, where two flowsheets are simulated to predict material and energy consumption. The simulation results prove that at least 350. 42 kW energy consumption can be reduced per hour to produce per ton biodiesel compared with data reported in previous references.
基金supported by the Natural Science Foundation of Shanxi Province(201601D102006)the Key Science and Technology Program of Shanxi Province,China(MD2014-09,MD2014-10)~~
文摘Composite solid base catalysts derived from Ca‐M‐Al(M=Mg,La,Ce,Y)layered double hydroxides(LDH)were synthesized,characterized and applied to the transesterification of methanol with propylene carbonate.X‐ray diffraction analyses of the catalysts show that all of the catalysts were in the form of composite oxides.Compared with the Ca‐Al LDH catalyst,the specific surface areas and pore volumes of the catalysts were increased with the introduction of Mg,La or Ce.The catalytic performance of these catalysts increases in the order of Ca‐Y‐Al<Ca‐Al<Ca‐Ce‐Al<Ca‐La‐Al<Ca‐Mg‐Al,which is consistent with the total surface basic amounts of these materials and the formation of especially strong basic sites following modification with Mg and La.The Ca‐Mg‐Al catalyst shows the highest(Ca+Mg):Al atomic ratio,indicating that it likely contains more unsaturated O2?ions,providing it with the highest concentration of very strong basic sites.The recyclability of these catalysts is improved following the addition of Mg,La,Ce or Y,with the Ca‐Mg‐Al maintaining a high level of activity after ten recycling trials.X‐ray diffraction analyses of fresh and used Ca‐Mg‐Al demonstrate that this catalyst is exceptionally stable,which could be of value in practical applications related to heterogeneous catalysis.
文摘Dispersion of KF on AlPO4-5 molecular sieve created basic sites and caused 1654 cm- band of bidentate carbonate in CO2 adsorption.After pre-treated above 823K. 5%KF/AlPO4-5exhibited basic catalytic activity in the isomerization of butenes at 273K. and the activity increasedwith the pre-treatment temperature up to 923K.
基金supported financially by the National Metal and Materials Technology Center,Thailandthe Center of Excellence on Petrochemical and Materials Technology,Thailand
文摘The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 C and atmospheric pressure.The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of96.7%under optimum conditions,while a methyl ester content over 94.5%was obtained in the packed-bed reactor.This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor.Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts.Leaching of the potassium species was negligible,whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.
文摘One-pot synthesis of Mg containing MCM-41(Mg-MCM-41) materials was respectively carried out by a room temperature(RT) method and a hydrothermal(HT) method for aldol condensation of 4-nitrobenzaldehyde and acetone and self-condensation of acetone. The RT method can prepare MCM-41 materials containing large amounts of Mg while maintaining the structural characteristics of MCM-41 even at very low Si/Mg ratios(large Mg loadings), but the HT method cannot. The RT method can also give more active catalysts than the HT method, because the catalysts prepared by the RT method are more basic than those prepared by the HT one. The characterization indicates that Mg atoms in the Mg-MCM-41 prepared by the RT method exist as MgO disperses well on the wall surface of pores, while those in Mg-MCM-41 prepared by the HT method are included in the bulk with a smectite-like structure.
文摘MgO/Al2O3 and Fe2O3/MgO/Al2O3 solid bases were prepared through mixing method. After sulfonated cobalt phthalocyanine （CoPcS） being supported on these solid bases, the catalytic performance of these catalysts was evaluated by means of mercaptan oxidation reaction. The samples were characterized by X-ray diffraction （XRD）, CO2 temperature-programmed desorption （CO2-TPD）, FTIR spectroscopy, and X-ray photoelectron spectroscopy （XPS）. Investigation was focused on the effect of Fe2O3 on activity, crystal structure, basicity, and stability of the catalyst and also on the role of Fe2O3 in the mercaptan oxidation processes. Test results have shown that the Fe2O3/MgO/Al2O3- CoPcS catalyst has a higher initial activity and a much longer service life than the MgO/Al2O3-CoPcS catalyst. The increased types of basic sites coupled with an enhanced oxidation ability resulted from the addition of Fe2O3 have contributed to the improvement of the catalytic activity of the MgO/Al2O3-CoPcS catalyst.
文摘For the development of fiber optics for the range from 0.2 to 50.0 μm, one needs light-stable, nonhygroscopic, ductile crystals that would be transparent within this spectral range and have a lack of cleavage, and from which the flexible infrared （IR） fibers are extruded. The crystals based on solid solutions of silver and monadic thallium haides meet the conditions listed above. Consequently, by differential thermal and x ray analyses, we study the TIBr-TII phase diagram using the crystals with optimal compositions, which we grow ourselves. We also manu- facture light-stable nanocrystalline IR fibers that are transparent at longer wavelengths compared with AgC1-AgBr fibers.
基金Project(2006BAE02B05) supported by the Key Projects in the National Science and Technology Pillar Program During the 11th Five-year Plan PeriodProject(2005CB221406) supported by the National Basic Research Program of China
文摘A new reaction system was designed to economically convert glucose to lactic acid environment-friendly. Hydrophobic ionic liquids were chosen as solvent that can promote the decomposition reaction of glucose, and the catalytic performance of the solid bases was evaluated. Both the reaction temperature and time can affect the yield of lactic acid. A high yield （97%） of lactic acid was achieved under the optimal reaction condition. The IH NMR spectra and HPLC-MS were used to identify the formation of the lactic acid and variations of ionic liquid. It is found that ionic-liquids have a unique solvent effect for glucose and bases. Water can be used as solvent to extract calcium lactate. This shows a great potential of hydrophobic ionic liquids in the solid bases catalyzed reaction that is limited by the weak solubility of solid bases in organic and water solution.
基金This work was supported by the National Natural Sciences Foundation of China under Grant No. 60007002.
文摘An automatic visible spectrometer based on a non-collinear acousto-optic tunable filter (AOTF) is constructed for high-speed spectrometry. Its spectral filtering characteristics, such as relationships between the radio-frequency (RF) driving frequency and the output central wavelength, the output bandwidth and the central wavelength, its typical spectral point spread function (PSF), and so on, are studied systematically. The preliminary measurement results of AOTF spectrometer show that it is a solid-state, high-speed, easily controllable by computer-programming, rugged and compact spectroscopic device in comparison with a conventional grating spectrometer, and has the potential for widespread spectrometric applications.
基金Project supported by National Basic Research Program of China(2010CB732300)111 Project(B08021)China Scholarship Council for the Joint-Training Scholarship Program with Institut de Recherches sur la Catalyse et l'Environnement de Lyon(IRCELYON)and Universite Claude Bernard Lyon 1(UCBL1)
文摘Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(grant Nos.91434206,21506034,and 21276270).
文摘A rapid and environmentally friendly approach to synthesize hierarchical sodalite from natural aluminosilicate mineral without the involvement of any mesoporogen or post-synthesis treatment was developed.This strategy involves three important steps:the first is the depolymerization of an aluminosilicate mineral into highly reactive silicon and aluminum species with ideal meso-scale structures through activation of a sub-molten salt.The second step is the hydrolysis and condensation of the activated aluminosilicate mineral into zeolitic precursors that also have a meso-scale structure.The third is the rapid zeolitization of the zeolitic precursors through the reversed crystal growth route at room temperature and ambient pressure to form hierarchical sodalite.The physicochemical properties of the as-synthesized sodalite were systematically characterized,and the formation mechanism of the hierarchical pore structure was discussed.When used as a solid base catalyst for Knoevenagel condensation,the as-synthesized sodalite and its potassium ion-exchanged product with hierarchical micro-meso-macroporous structure both exhibited high catalytic activity and product selectivity.
基金supported by the Zhangjiang Science and Technology Development Foundation of Guangdong,China (2009C3101015)Doctoral Starting Foundation of Guangdong Medical College (XB0811)
文摘A facile route for the synthesis of dimethyl adipate （DAP） from cyclopentanone and dimethyl carbonate （DMC） in the pres- ence of solid base catalysts has been developed. It was found that the intermediate carbomethoxycyclopentanone （CMCP） was produced from cyclopentanone with DMC in the first step, and then CMCP was further converted to DAP by reacting with a methoxide group. The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the a-position by base sites, and solid bases with moderate strength, such as MgO, favor the formation of DAP.
基金This work was supported by the National Natural Science Foundation of China(Nos.21878149,22078155 and 21722606)National Science Fund for Distinguished Young Scholars(No.22125804)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Ordered porous solid strong bases(OPSSBs)have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions.The main obstacle for fabricating OPSSBs is the requirement of high temperature to produce strong basicity on ordered porous materials.For example,the temperatures of 600-650℃ are required for the decomposition of base precursor NaNO_(3)to basic sites on mesoporous silica SBA-15 and zeolite Y.Such high decomposition temperatures are energy-intensive and harmful to the structure of supports.Herein,we report the fabrication of OPSSBs by utilizing the redox interaction between base precursor and low-valence metal centers(e.g.,Cr^(3+))in metal-organic frameworks(MOFs).The base precursor NaNO_(3)on MIL-101(Cr)can be converted to basic sites entirely at 300℃,which is quite lower than those of the conventional thermal conversion on SBA-15 and zeolite Y(600-650℃).The exploration on decomposition mechanism reveals that the valence change of Cr^(3+)to Cr^(6+)takes place during the conversion of NaNO_(3)to basic sites.In this way,MOFs-derived base catalysts have been synthesized successfully by the host-vip redox strategy and exhibit high catalytic activity in typical base-catalyzed reactions.
