微波场中T型分子筛的合成及晶化研究

研究了微波场中T型分子筛的结晶过程。考察了微波加热体系中合成参数如合成时间、溶胶组成、反应压力和模板剂用量对分子筛晶化的影响。微波加热的主要优点是减少合成时间,无模板剂的溶胶在普通加热条件下的晶化时间需要120 h,而在微波场中则仅需要20～25 h。另一方面,由于微波的快速加热特性促进了稳定相钙十字沸石的生成,从而减小了次稳定相T型分子筛的结晶区间。在未添加模板剂条件时,100 ℃下微波水热合成T型分子筛的结晶区间为：20≤n_SiO2/n_Al2O3≤22和0.31≤ n_M2O/n_SiO2≤0.33(其中M₂O=Na₂O+K₂O, n_Na/n_K=3和n_M2O/n_SiO2=11.70)。在普通加热和微波加热合成体系中,添加模板剂均能扩大结晶区间,同时还可以进一步减少合成时间。     

微波场中甲烷部分氧化制合成气 Ⅰ.Ni/La_2O_3催化剂在微波场中的升温行为及催化活性

微波场中甲烷部分氧化制合成气Ⅰ．Ｎｉ／Ｌａ２Ｏ３催化剂在微波场中的升温行为及催化活性毕先钧段爱红（云南师范大学化学系，昆明６５００９２）王真洪品杰戴树珊（云南大学化学系，昆明６５００９１）关键词微波，甲烷，合成气，氧化镍，氧化镧分类号Ｏ６４３近年来，...     

Hot or not—the influence of elevated temperature and microwave irradiation on the solid phase synthesis of an affibody

Despite the advances of solid phase peptide synthesis (SPPS) the synthesis of long peptides is still challenging. Microwave irradiation and conventional heating are considered to improve the efficiency of SPPS. It has been shown that conventional heating and heating by microwave irradiation improves the efficiency of solid phase synthesis of peptides that are prone to aggregation as compared to the synthesis at room temperature. In this Letter, the influence of elevated temperature and microwave irradiation on the homogeneity of the synthesis product of a 58-mer peptide affibody has been compared. A detailed analysis by high resolution HPLC and LC-MS mass spectrometry using a high-mass resolution Orbitrap Exactive mass spectrometer was performed. This study revealed that neither thermal heating nor microwave heating improves the yield and purity of the crude product as compared to the synthesis at room temperature. In contrast, the formation of undesirable side products rather increased by microwave irradiation. These results indicate that neither heating nor microwave enhancement of solid phase synthesis does allow a significant improvement of peptide sequences with a low aggregation potential.     

Supramolecular Interactions and Morphology Control in Microwave Synthesis of Nanoporous Materials

Application of a microwave technique to the conventional hydrothermal process is gaining importance, especially, in the synthesis of nanoporous materials. This microwave technique is regarded as a novel synthesis tool because it gives several beneficial advantages such as homogeneous nucleation, rapid synthesis, formation of uniform crystals, and small crystallites, facile morphology control, energy efficiency and so on. Recently, it was found that it offers an efficient way to control the crystal morphology, size and orientation, and even crystalline phase which are required for many emerging applications of nanoporous materials. This review summarizes recent work on the microwave effect, supramolecular interactions and control of crystal morphology upon microwave synthesis of nanoporous materials performed by the present authors. Synthesis and morphology control of nanoporous materials such as ZSM-5, zeolite beta, metallosilicates, AlPO, MCM-41, SBA-15, SBA-16, etc. have been accomplished with microwave irradiation. In particular, the rapid nucleation and crystallization of ZSM-5 zeolite under microwave irradiation made it possible to enable the continuous microwave synthesis, implying a great industrial and technological importance. The formation of nanoporous materials, especially, silicate or aluminosilicate molecular sieves was described on the basis of supramolecular interactions between organic template molecules and silicate species under microwave irradiation. Besides decreasing synthesis time, it was duly demonstrated that the microwave technique provides an effective way to control particle size distribution and macroscopic morphology in the synthesis. Moreover, for the application of these porous materials, microwave-induced nanofabrication of microporous and mesoporous materials is more important than that of simple porous materials.     

微波水热合成Mn-Ti-Al-MCM-41分子筛及其催化双氧水环氧化苯乙烯的性能

采用原位微波水热合成Mn-Ti-Al-MCM-41介孔分子筛,并以双氧水为氧化剂和微波加热,研究了该介孔分子筛在苯乙烯环氧化反应中的催化性能.利用XRD、29SiMAS-NMR、N2吸附、SEM-EDS和HRTEM手段对该材料进行了表征,结果表明它具有典型的六方相介孔结构、高的比表面积以及窄的孔径分布.本实验表明Mn-Ti-Al-MCM-41的新颖合成方法加速了整个合成时间:从几天到几个小时.在催化苯乙烯液相环氧化实验中该材料具有较高的催化活性.而且利用本实验合成的介孔分子筛与传统方法制备的在较大程度上提高了对苯基环氧乙烷的选择性.     

Dawson型磷钨钼杂多酸的制备及其对H2O2氧化环己酮制己二酸的催化

采用水热法制备了新型H6P2W9Mo9O62.24H2O催化剂,并用UV-Vis、FT-IR和TG-DTA等测试技术对催化剂进行了表征。以微波促进30%过氧化氢氧化环己酮制备己二酸合成反应为探针,考察了催化剂的催化性能。通过正交实验探讨了几种因素对反应的影响,确定了优化工艺条件为:n(环己酮)∶n(过氧化氢)∶n(草酸)∶n(催化剂)=100∶400∶1.25∶0.25,反应温度100℃,微波辐射功率400 W,反应时间3.5 h,己二酸产品的收率达87.33%,纯度可达99.7%。反应结束后,将反应后含催化剂的溶液浓缩至一定浓度,催化产率降低,重复使用5次收率降低为45.89%。     

Microwave Effect in the Fast Synthesis of Microporous Materials: Which Stage Between Nucleation and Crystal Growth is Accelerated by Microwave Irradiation?

Microporous materials, such as silicalite-1 and VSB-5 molecular sieves, have been synthesized by both microwave irradiation (MW) and conventional electric heating (CE). The accelerated syntheses by microwave irradiation can be quantitatively investigated by various heating modes conducted in two steps such as MW-MW, MW-CE, CE-MW, and CE-CE (in the order of nucleation-crystal growth). In the case of synthesis by MW-CE or CE-MW, the heating modes were changed for the second step just after the appearance of X-ray diffraction peaks in the first step. We have quantitatively demonstrated that the microwave irradiation accelerates not only the nucleation but also crystal growth. However, the contribution to decrease the synthesis time by microwave irradiation is larger in the nucleation stage than in the step of crystal growth. The crystal size increases in the order of MW-MW相似文献   

A Critical Assessment of the Specific Role of Microwave Irradiation in the Synthesis of ZnO Micro‐ and Nanostructured Materials

A rapid, microwave‐assisted hydrothermal method has been developed to access ultrafine ZnO hexagonal microrods of about 3–4 μm in length and 200–300 nm in width by using a 1:5 zinc nitrate/urea precursor system. The size and morphology of these ZnO materials can be influenced by subtle changes in precursor concentration, solvent system, and reaction temperature. Optimized conditions involve the use of a 1:3 water/ethylene glycol solvent system and 10 min microwave heating at 150 °C in a dedicated single‐mode microwave reactor with internal temperature control. Carefully executed control experiments ensuring identical heating and cooling profiles, stirring rates, and reactor geometries have demonstrated that for these preparations of ZnO microrods no differences between conventional and microwave dielectric heating are observed. The resulting ZnO microrods exhibited the same crystal phase, primary crystallite size, shape, and size distribution regardless of the heating mode. Similar results were obtained for the ultrafast preparation of ZnO nanoparticles with diameters of approximately 20 nm, synthesized by means of a nonaqueous sol–gel process at 200 °C from a Zn(acac)₂ (acac=acetylacetonate) precursor in benzyl alcohol. The specific role of microwave irradiation in enhancing these nanomaterial syntheses can thus be attributed to a purely thermal effect as a result of higher reaction temperatures, more rapid heating, and a better control of process parameters.     

Novel Two‐Dimensional Porous Materials for Electrochemical Energy Storage: A Minireview

Two dimensional (2D) porous materials have great potential in electrochemical energy conversion and storage. Over the past five years, our research group has focused on Simple, Mass, Homogeneous and Repeatable Synthesis of various 2D porous materials and their applications for electrochemical energy storage especially for supercapacitors (SCs). During the experimental process, through precisely controlling the experimental parameters, such as reaction species, molar ratio of different ions, concentration, pH value of reaction solution, heating temperature, and reaction time, we have successfully achieved the control of crystal structure, composition, crystallinity, morphology, and size of these 2D porous materials including transition metal oxides (TMOs), transition metal hydroxides (TMHOs), transition metal oxalates (TMOXs), transition metal coordination complexes (TMCCs) and carbon materials, as well as their derivatives and composites. We have also named some of them with CQU‐Chen (CQU is the initialism of Chongqing University, Chen is the last name of Lingyun Chen), such as CQU‐Chen‐Co?O‐1, CQU‐Chen‐Ni?O?H‐1, CQU‐Chen‐Zn?Co?O‐1, CQU‐Chen‐Zn?Co?O‐2, CQU‐Chen‐OA?Co‐2‐1, CQU‐Chen‐Co?OA‐1, CQU‐Chen‐Ni?OA‐1, CQU‐Chen‐Gly?Co‐3‐1, CQU‐Chen‐Gly?Ni‐2‐1, CQU‐Chen‐Gly?Co?Ni‐1, etc. The introduction of 2D porous materials as electrode materials for SCs improves the energy storage performances. These materials provide a large number of active sites for ion adsorption, supply plentiful channels for fast ion transport and boost electrical conductivity and facilitate electron transportation and ion penetration. The unique 2D porous structures review is mainly devoted to the introduction of our contribution in the 2D porous nanostructured materials for SC. Finally, the further directions about the preparation of 2D porous materials and electrochemical energy conversion and storage applications are also included.     

Investigation of porous Ni-based metal-organic frameworks containing paddle-wheel type inorganic building units via high-throughput methods

In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2, 3a, 3b, and 3c. All compounds were structurally characterized. In addition to IR, elemental and TG analyses, gas and vapor sorption experiments were carried out.     

Microwave Effect On Partial Oxidation of Methane to Syngasover Ni/ZrO_2

MicrowavedielectricheatingisfoundtobeanalternativeproceduretoconventionalconductiveheatingforintroducingenergyintocheInicalreactionsandseemstobeawell-suitedprocessforactivatingsolidcatalystS'-'.TheoriginofthendcrowavecouplingdielectricheatingIiesinthecapacityofanelectricfieldtopolarizechargesinamaterial.TheheatingeffectismoreemphasizedwhentheirradiatedmaterialhasastrongdipoIarcharacter.ThisisparticularlythecasewiththosecatalystswhosesupportisanoxidewithnumerouspoIarOHgroups.Moreover,whenpol…     

Two-dimensional carboxylate bridged network of europium(III)-transition metal(II) glutarate compounds

Four new heterometallic glutarate coordination polymers, [Eu2M(H2O)4][O2C(CH2)3CO2]4.2H2O (M = Mn (1), Fe (2), Co (3) and Ni (4)) have been obtained under hydrothermal synthesis. The single-crystal X-ray diffraction analyses showed that they have two-dimensional frameworks based on the linear polyhedral chains consisting of two nine-coordinated Eu(III)O9 and a six-coordinated M(II)O6. These 1-D MO6-Eu2O16 chains are cross-linked by glutarate ligands as an interchain pillared architecture, whose conformations vary depending upon the transition metals. The magnetic behavior of the compounds show a weak antiferromagnetic interaction, in which shielding of the 4f electrons by the outer shell electrons effectively precludes significant coupling interactions between the Eu-4f electrons and transition metal (M)-3d electrons.     

微波场对固态氧离子导体上的甲烷氧化偶朕的影响

研究了微波场下甲烷在具有Bi2O3结构的固态氧离子导体上氧化偶联反应行为．与常规加热条件下的反应结果相比较,微波辐照下的反应有如下特点;（1）在达到相同甲烷转化率时,微波辐照下所需床层温度要远低于常规加热条件下所需床层温度;（2）微波辐照下,甲烷氧化偶联产物中C2烃的选择性普遍较高,在低温区尤为突出．微波场下甲烷偶联产物乙烷、乙烯的再氧化得到一定程度的抑制,致使微波场下的甲烷氧化偶联反应通常有较低的烯／烷比．     

一种多核镍取代砷钨酸盐对罗丹明-B染料光催化降解行为的影响

在前期研究中,我们在水热条件下合成了一种多核镍取代砷钨酸盐[化合物(1)][Ni(H2O)(en)2]2 [Ni(H2O)3(en)][Ni(H2O)(en)]{[(α-AsW6 O26) Ni6(OH)2 (en)2.5(B-α-AsW9O34)]2 H4[W4O16][Ni4(H2O)2(en)2]2 }·13H2...     

Fast synthesis of temperature-sensitive PNIPAAm hydrogels by microwave irradiation

A novel method, microwave irradiation synthesis, is proposed for the preparation of thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The PNIPAAm hydrogels were separately synthesized by using microwave irradiation method and water-bath heating method. Chemical groups, lower critical solution temperature (LCST) and surface morphology of these PNIPAAm hydrogels were characterized by FT-IR, DSC and SEM. Swelling ratios of the gels were measured gravimetrically in the temperature range from 10.0 to 60.0 °C. Results showed that (1) the use of microwave irradiation can greatly shorten the reaction time required for PNIPAAm hydrogel synthesis from several hours to several minutes in comparison with water-bath heating method, and obviously improve the yields of the PNIPAAm gels, which were up to 99% after a short reaction time; (2) SEM micrographs and textural measurement revealed that the gels synthesized using microwave irradiation had more porous structure, and their average pore sizes and specific surface areas were larger than those of the gels synthesized using water-bath heating method; and (3) the PNIPAAm hydrogels synthesized using microwave irradiation had much higher swelling ratios at 10.0 °C below the LCST, and had lower swelling ratio at 60.0 °C above the LCST compared to the hydrogels synthesized by water-bath method.     

微波辐照下（Bi_2O_3）_（0．8）（La_2O_3）_（0．2）固熔体对甲

微波辐照下（Ｂｉ_２Ｏ_３）_（０．８）（Ｌａ_２Ｏ_３）_（０．２）固熔体对甲烷氧化偶联的催化行为陈长林,洪品杰,戴树珊,阚家德（云南大学化学系,昆明,６５００９１）关键词微波,甲烷氧化偶联,（Ｂｉ_２Ｏ_３）_（０．８）（Ｌａ_２Ｏ_３）_（０．２）甲烷氧化...     

有序介孔碳CMK-3微波负载NiO及其电容性能研究

微波法负载具有简便、快速、均匀的优点. 本文尝试以乙二醇为还原剂, Ni(Ac)₂为Ni源, 通过微波辐射负载及低温空气煅烧在CMK-3上形成NiO. 对样品进行X射线衍射(XRD)、透射电子显微镜(TEM)、N₂吸脱附等结构表征及循环伏安(CV)等电化学性能测试. 结果显示, 微波法并经低温空气煅烧后有序介孔碳CMK-3的小角XRD峰强度变弱、比表面积下降、孔容减小, 但却使其比电容从229.3 F/g提高到295.9 F/g, 大于文献报导中介孔碳负载MnO₂, RuO₂•xH₂O后的比电容值. 由此说明微波法是有效的负载方法, 具有较好的应用前景.     

微波作用下的多肽固相缩合反应及动力学研究

分别在微波作用以及传统加热两种方式下, 研究了Fmoc-Val-OH与NH₂-Tyr(t-Bu)-Wang树脂的固相缩合反应及其动力学. 测定了温度变化对反应速率的影响, 并获得了两种方式下的缩合反应的宏观动力学参数: 300 W微波作用下表观缩合反应级数为2.3, 活化能为104.7 kJ/mol; 传统方法中表观反应级数为2.9, 活化能为142.4 kJ/mol. 微波作用将常规条件下的连接率由68%提高到95%, 而所需时间降为常规条件的1/14.     

Hybrid organic-inorganic 1D and 2D frameworks with epsilon-Keggin polyoxomolybdates as building blocks

Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36(OH)4[La(H2O)4]]5+ polyoxocation with glutarate (C5H6O(2)(2-)) and squarate (C4O(4)(2-)) organic ligands. [epsilon-PMo12O37(OH)3[La(H2O)4(C5H6O4)0.5]4].21 H2O (1) and [epsilon-PMo12O39(OH)[La(H2O)6]2-[La(H2O)5(C4O4)0.5]2].17 H2O (2) form unprecedented 1D chains built from alternating polyoxocations and organic ligands connected through LaO links. The structures of these materials are compared to the 2D hybrid organic-inorganic framework [NC4H12]2-[Mo22O52(OH)18[La(H2O)4]2[La(CH3CO2)2]4].8H2O (3) isolated from the hydrothermal reaction of elemental precursors (MoO(4)(2-), Mo, La3+) in acetate buffer. Compound 3 is built from previously undescribed polyoxometalate units with twenty-two MoV centers capped by six La3+ ions, four of which are bridged by acetate ligands.     

Microwave synthesis of zinc sulfite and porous zinc oxide microrods

ZnSO(3) microrods with uniform size and shape can be prepared under microwave irradiation at much higher speed than a conventional heating bath, usually in minutes. The annealing of ZnSO(3) microrods produced porous ZnO microrods with pore size between 50-200 nm.