ZIF-67的制备和热稳定性能研究

通过控制Co(NO_3)_2·6H_2O和2-甲基咪唑的摩尔比,即分别为1∶4,1∶8,1∶16和1∶32,在室温下合成出四组不同的ZIF-67产物。XRD结果表明四种不同配比的反应物均能采用溶剂热方法合成出具有高度结晶的纯相ZIF-67材料。SEM观察发现不同配比所合成的ZIF-67只在粒径大小和分布上有较大的差异。随着2-甲基咪唑含量逐渐增加,ZIF-67晶粒变得越来越不规整,分布更不均匀。TG分析表明当两者的摩尔比是1∶4时,合成的ZIF-67有较好的热稳定性。     

ZIF-67与ZIF-8对水溶液中碘离子吸附性能研究

以Co(NO_3)_2、Zn(NO_3)_2、2-甲基咪唑和甲醇为原料制备出两种金属骨架结构材料ZIF-67和ZIF-8,并以该两种材料对碘离子进行了吸附实验,探究了溶液pH值、吸附时间、温度等因素对两种材料吸附溶液中碘离子的吸附效果及其影响。结果表明,两种材料对碘离子均在pH为7的水溶液体系中达到最大吸附量,在18 h左右达到吸附动态平衡。拟合结果表明,ZIF-67对碘离子的吸附符合Langmuir吸附等温线,ZIF-8对碘离子的吸附更符合Freundlich吸附等温线。最大吸附量分别为141.81 mg/g和474.02 mg/g。两种材料对碘离子的吸附行为更符合准一级动力学模型,吸附类型属于单分子层吸附。     

ZIF-67/聚磷腈复合微球的可控制备及表征

以聚(环三磷腈-co-4,4’-二羟基二苯砜)微球(PZS)作为ZIF-67晶体的生长基板,通过原位自组装法设计制备了一种新型核壳结构的ZIF-67/聚磷腈复合微球ZIF-67@PZS。通过调节原料配比确定了ZIF-67@PZS较佳的结构形貌。结果表明,在六水合硝酸钴∶2-甲基咪唑∶三乙胺的摩尔比为1∶4∶4,PZS与六水合硝酸钴的质量比为5∶1的条件下,制备的聚磷腈复合微球ZIF-67@PZS的品质较高;相较于ZIF-67和PZS,ZIF-67@PZS的初始分解温度分别提高了119℃和20℃,800℃的质量保留率分别提高了25.4%和4.7%,表现出更加优异的热稳定性能;通过观察梯度时间下的扫描电子显微镜照片,进一步推测了ZIF-67@PZS的可能形成机理。     

基于生物质模板制备ZIF-8及抗菌性能

为赋予皮革表面优异的抗菌性，以己内酰胺(CPL)改性酪素(CA)(CA-CPL)胶束为模板原位生长金属有机骨架化合物，类沸石咪唑酯骨架(ZIF-8)，得到了CA-CPL@ZIF-8，并将其应用于皮革涂饰中。采用FTIR、XRD、SEM、TEM、N₂吸附-脱附对样品进行了表征。对涂饰后皮革的抗菌、力学和卫生性能进行了测试。结果表明，通过调整生物质模板CA-CPL的尺寸与形貌，成功生长出晶体结构完整的CA-CPL@ZIF-8。随着CA-CPL@ZIF-8添加量(以CA-CPL质量计，下同)的增加，涂饰后皮革对大肠杆菌和金黄色葡萄球菌产生了明显的抗菌效果，力学性能和卫生性能相应提升；当其添加量为0.8%时，涂饰后皮革对金黄色葡萄球菌的抑菌圈为4mm，抗张强度和断裂伸长率分别可达6.32MPa和56%；当其添加量为0.5%时，透气性和透水汽性可达1522 mL/(cm²·h)和353 mg/(10 cm²·24 h)。     

ZIF-67衍生的多孔钴氧化物碳纤维制备及其储锂性能

以六水合硝酸钴、2-甲基咪唑为溶质,甲醇为溶剂,采用室温共沉淀法制备ZIF-67,并采用静电纺丝技术将ZIF-67掺杂在碳纤维中。研究了此负极材料的结构、形貌与电化学性能。由电子显微镜（SEM）、能谱分析（EDS）、综合热分析、X射线衍射（XRD）以及LAND电化学测试结果表明：以ZIF-67衍生的多孔钴氧化物碳纤维作为负极材料,具有较高比容量、良好的循环稳定性(在电流密度为100 mA·g^-1时,100次循环后比容量仍具有597.7 mAh·g^-1)。     

合成多级孔分子筛的研究进展

构建多级孔分子筛是提高分子筛扩散性能的重要手段,是目前催化领域研究的热点之一。多级孔分子筛的合成方法较多,从脱除骨架元素、原位合成和重结晶3个方面综述近年来多级孔分子筛的合成研究。脱除骨架元素主要有蒸汽处理和化学处理;原位合成法主要包括硬模板法和软模板法;重结晶是分子筛晶体经碱溶解后在表面活性剂条件下自组装形成多级孔分子筛,并对多级孔分子筛的发展前景进行展望。     

多级孔分子筛的合成研究进展

多级孔分子筛由于其高的外比表面积、良好的传热及扩散性能,在重油裂化、异丙苯制备、加氢异构化等催化反应中显示出优良的性能。综述近年来多级孔分子筛的合成进展,着重介绍多级孔分子筛的合成方法、合成机理及性质特点。     

PET synthesis in the presence of lanthanide catalysts

Syntheses of poly(ethylene terephthalate), PET, by transesterification of dimethyl terephthalate with ethylene glycol in the presence of well-known catalysts and various lanthanide compounds were performed. Lanthanide catalysts appeared to be much more efficient in the first stage of the process (transesterification in the presence of an excess of ethylene glycol), and less active in polycondensation. PET produced with lanthanides was found to possess enhanced thermal and hydrolytic stability as compared to PET synthesized with well-known catalysts and commercial PET. © 1995 John Wiley & Sons, Inc.     

晶种法合成整体式多级孔ZSM-5分子筛

以四丙基氢氧化铵为模板,采用原位水热法,添加Silicalite-1晶种和十六烷基三甲基溴化铵,一步合成直径约为2cm、高约为0.8cm、中间部位向内凹、边缘部位凸起且表面较光滑的分子筛圆片集聚体。XRD、SEM和N2吸附-脱附表征结果表明,该分子筛圆片集聚体是由小晶粒堆积成的具有微孔和介孔的多级孔ZSM-5分子筛。     

Catalytic activity of ZIF-8 in the synthesis of styrene carbonate from CO2 and styrene oxide

The catalytic activity of ZIF-8 in the synthesis of styrene carbonate from carbon dioxide and styrene oxide is presented. ZIF-8 crystals displayed catalytic activity even at temperatures as low as 50 °C, with styrene carbonate yields as high as ~ 54% at 100 °C. In contrast to many prior-art catalysts, solvents or co-catalysts were not required. Pyridine and ammonia were used as probe molecules to estimate the type and density of acid sites in fresh and reused ZIF-8 catalysts. DRIFT spectroscopy of adsorbed pyridine revealed the presence of both Brönsted (B) and Lewis (L) acid sites. The B-sites have nearly vanished in the case of recycled ZIF-8 catalysts. The simultaneous presence of both the acid sites and the nitrogen basic moieties from the imidazole linker in ZIF-8 promoted the adsorption of the CO₂ on the solid surface and its further conversion to the cyclic carbonate. The ZIF-8 catalysts could be recycled and reused without significant loss in catalytic activity.     

水中合成2-苯甲酰基-1,3,5-三苯基-4,4-二腈基环己醇的洁净方法

在水中以苯亚甲基苯乙酮和丙二腈为原料,十六烷基三甲基溴化铵(HTMAB)催化下,合成了标题化合物。考察了不同催化剂、催化剂用量及不同溶剂对反应的影响。产物的结构经IR和1HNMR进行了表征确证。该方法具有反应条件温和、操作简便、环境友好的优点。     

PET synthesis in the presence of new aluminum catalysts

A new polycondensation catalyst (ethylene glycol aluminum) was synthesized and applied in PET synthesis. It has been characterized by spectral studies (IR, NMR). The catalytic activity of organic aluminum compound was discussed in this paper. In this investigation, the synthesis of poly(ethylene terephthalate) (PET) is presented using ethylene glycol (EG) and terephthalic acid (TPA). The result proved that ethylene glycol aluminum was the real catalytic material. And it was proved to be the most efficient catalyst for the polycondesation reaction among the organic aluminum compounds. Similar catalytic activity has been observed for ethylene glycol aluminum compared to ethylene glycol antimony. The esterification reaction was monitored by measuring the distilled water as a function of time and the modeling of this process was carried out from these data. The received PET samples were characterized by viscometry, carboxyl end-group content and diethylene glycol (DEG) content. A mechanism of aluminum catalysis has been proposed to explain these observations.     

1,3,-三苯基苯的超声快速有效合成研究

以苯乙酮为原料,氯化亚砜(Cl2OS)为催化剂,在超声的条件下,合成三苯基苯,并探讨了超声功率,超声时间等因素对三苯基苯合成的影响,确定了合成反应的最佳条件为:超声功率60Hz,超声时间40min.在此条件下,收率可达83％～86％,与常规回流法相比,达到同等的产率,反应时间缩短了20min.目标物分子的结构经1HNM...     

A hierarchical approach for the synthesis of batch water network

This work addresses the problem of synthesising cost-effective batch water networks where a number of process sources along with fresh water are mixed, stored, and assigned to process sinks. In order to address the complexity of the problem, a three-stage hierarchical approach is proposed. In the first stage, global targets are identified by formulating and solving a linear transportation problem for minimum water usage, maximum water recycle, and minimum wastewater discharge. These targets are determined a priori and without commitment to the network configuration. Next, a network with minimum number of tanks is synthesised by solving a mixed-integer non-linear program. The bilinear constraints are relaxed to transform the program into a mixed-integer linear program that is globally solvable. The third stage is aimed at simplifying the network configuration by minimising the number of network inter-connections. Insights gained from the water pinch analysis are also incorporated into the approach to further reduce the water flows via the placement of water regeneration unit. A case study is solved to illustrate the effectiveness of the proposed procedure.     

The polycondensation of dimethyl terephthalate and ethylene glycol in the presence of dye derivatives of 1,3,5-sym-triazine

Two new triazine-based dyes have been prepared with the following general formula: in which R = ? HNCH₂CH₂OH or ? NHCH₂COOH. As a result of the presence of suitable functional groups, these compounds can be incorporated in the polycondensation process which gives colored polyethylene glycol terephthalates (PEGT). By means of a spectrophotometric investigation, it has been demonstrated that the dye does not change its structure under high temperature or its incorporation in the polymer chain. A colorimetric study has been made of the dye content of the polymer as related to the quantity initially taken for the reaction. It has been shown that the inclusion of the dye in the polycondensation process does not affect notably the molecular weight, melting point, and the polydispersion of the polymers. Intensive coloration can be obtained with very low concentrations of the dye, 0.1–0.5%. By comparing the infrared spectra of the polymer and the pure dyes, the dyes have been demonstrated to be bound to the polymer molecule. Since the dye is part of the basic chain of PEGT, the polymers retain their color after repeated reprecipitation. The proposed method can be used for the preparation of saturated polyesters of divers properties and persistent colors.     

Synthesis of carbon nanotubes by detonation of 2,4,6-triazido-1,3,5-triazine in the presence of transition metals

The formation of carbon nanotubes via explosive decomposition of an energetic precursor, 2,4,6-triazido-s-triazine C₃N₁₂, was investigated with respect to the presence of the transition metals Fe, Ni, Cu, Ti and the degree of confinement of the explosive charge. The carbonaceous detonation products were characterized by transmission and scanning electron microscopy, energy dispersive X-ray analysis and infrared absorption spectroscopy. Multi-walled carbon nanotubes with diameters from 50 to 150 nm and a variety of morphologies were found. Metal particles in the tubes and at some of the tube ends indicate a catalytic growth mechanism.     

固相法合成ZIF-8的表征和催化性能研究

以二甲基咪唑为有机配体,ZnO为Zn源,采用固相法制备了系列沸石咪唑酯骨架结构材料ZIF-8(S),并用XRD、FTIR、N_2吸附、SEM等手段进行了表征。主要考察了固相法制备ZIF-8的合成条件,并与常规溶剂法合成的ZIF-8(MeOH)进行了比较研究。结果表明,采用固相法可成功制备出高结晶度纯相的ZIF-8,且所制备的ZIF-8(S)与在甲醇体系中合成的ZIF-8(MeOH)相比,结晶度高,晶体粒度大,但由于其较小的外表面积,在丙二腈与苯甲醛的Knoevenagel缩合反应中的催化活性相对较低,对简单高效、环境友好的固相合成法制备ZIF-8的性能与应用研究具有重要意义。     

ZIF-67衍生Co/NC多孔碳材料的改性及其电催化水氧化性能

通过将前体ZIF-67高温热解并采用Na BH₄还原的方法制得表面富含氧空位的多孔碳复合材料(R-Co/NC-800)。利用X射线衍射(XRD)、场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、X射线光电子能谱仪(XPS)等手段对材料的物相、形貌、元素分布以及表面化学键结构等进行了表征;采用线性扫描伏安法(LSV)等方法研究了材料的电催化水氧化活性。结果表明制得的多孔碳复合材料(R-Co/NC-800)与未经NaBH₄还原处理的Co/NC-800样品对比,其表面氧空位浓度明显增加,形成新的催化活性位点,有效提升了电催化水氧化活性。在1.0 mol/L KOH溶液中,达到10 mA/cm²的电流密度,所需过电势仅为287 mV,同时表现出优异的电化学稳定性。     

Matrix synthesis of water-soluble polyaniline in the presence of polyelectrolytes

The matrix polymerization of aniline hydrochloride in the presence of polyanions with different chemical structures and molecular masses is studied. Poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and poly(4-styrenesulfonic acid) or its sodium salt are used as polyelectrolyte matrices. It is shown that, if the polymerization of aniline hydrochloride is conducted in the presence of a polyelectrolyte matrix, water-soluble polyelectrolyte complexes in which polyaniline occurs in the form of an emeraldine salt are formed. The mechanism of polymerization is advanced. It is found that the sizes of polyaniline complexes in water are independent of the molecular mass of the polyelectrolyte matrix and its chemical structure.     

Kinetics of the solid-phase synthesis of mullite in the presence of topaz

Results of a kinetic study of solid-phase interactions in stoichiometric oxide mixtures of mullite composition are reported. The mechanism of mullitization, irrespective of the oxide form (crystalline or amorphous), is diffusive in character. Topaz added in small quantities accelerates the process through generating surface and structure imperfections and activating the diffusion of reactants owing to the assistance of gaseous fluorides released by topaz. The secondary mullite produced by thermal degradation of topaz facilitates the formation of nucleation centers for topochemical reactions and activates the mullite crystallization.__________Translated from Novye Ogneupory, No. 10, pp. 83 – 90, October, 2004.For previous papers, see Novye Ogneupory, Nos.7 – 9 (2004).