CO_2/H_2O体系中金属选择性还原芳香硝基物研究

CO2溶于H2O形成碳酸,在一定温度、压力下,体系的pH值可达2.8,是一种自中和的酸性体系。利用CO2和H2O原位形成的碳酸代替传统金属还原芳香硝基物方法中的永久性无机酸或有机酸,反应结束后,无需加碱中和体系,体系因没有盐的生成,不仅减少了后处理的麻烦,避免了对环境的污染;而且CO2和H2O都可以循环使用。是一种具有环境友好特性的绿色化学方法。本文报告在此体系中,1)应用铁粉选择性还原各种芳香硝基物制备芳胺的反应研究及2)应用锌粉选择性还原芳香硝基物的N-芳基羟胺反应研究。

金属离子选择性的甲硫氨酰氨肽酶抑制剂研究进展

甲硫氨酰氨肽酶(MetAP)是潜在的抗细菌、抗真菌和肿瘤治疗的分子靶点。MetAP是一类两价金属离子依赖的蛋白水解酶。然而,生理状态下,MetAP在细胞内结合并利用的金属离子类型目前还没有定论。因而,研究和发展不同金属离子选择性的甲硫氨酰氨肽酶抑制剂对细胞内源性金属离子的解析以及新型抗肿瘤及抗感染药物的研发具有重要意义。

Evolution of microstructure and mechanical properties in multi-layer 316L-TiC composite fabricated by selective laser melting additive manufacturing

In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,consisting of 316L stainless steel,316L-5 wt%TiC and 316L-10 wt%TiC,were additively manufactured.The microstructure of these layers was characterized by optical microscopy(OM)and scanning electron microscopy(SEM).X-ray diffraction(XRD)was used for phase analysis,and the mechanical properties were evaluated by tensile and nanoindentation tests.The microstructural observations show epitaxial grain growth within the composite layers,with the elongated grains growing predominantly in the build direction.XRD analysis confirms the successful incorporation of the TiC particles into the 316L matrix,with no unwanted phases present.Nanoindentation results indicate a significant increase in the hardness and modulus of elasticity of the composite layers compared to pure 316L stainless steel,suggesting improved mechanical properties.Tensile tests show remarkable strength values for the 316L-TiC composite samples,which can be attributed to the embedded TiC particles.These results highlight the potential of SLM in the production of multi-layer metal-ceramic composites for applications that require high strength and ductility of metallic components in addition to the exceptional hardness of the ceramic particles.

Single atom doping induced charge-specific distribution of Cu1-TiO_(2) for selective aniline oxidation via a new mechanism

Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2)) is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2) from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2) did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2) catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2) generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.

Enhancing photo-generated carriers transfer of K-C_(3)N_(4)/UiO-66-NH_(2) with Er doping for efficient photocatalytic oxidation of furfural to furoic acid

Biomass-derived platform molecules,such as furfural,are abundant and renewable feedstock for valuable chemical production.It is critical to synthesize highly efficient photocatalysts for selective oxidation under visible light.The Er@K-C_(3)N_(4)/UiO-66-NH_(2) catalyst was synthesized using a straight-forward hydrothermal technique,and exhibited exceptional efficiency in the photocatalytic oxidation of furfural to furoic acid.The catalyst was thoroughly characterized,confirming the effective adjustment of the band gap energy of Er@K-C_(3)N_(4)/UiO-66-NH_(2).Upon the optimized reaction conditions,the conversion rate of furfural reached 89.3%,with a corresponding yield of furoic acid at 79.8%.The primary reactive oxygen species was identified as·O_(2)^(-) from ESR spectra and scavenger tests.The incorporation of Er and K into the catalyst enhanced the photogenerated carriers transfer rate,hence increasing the separating efficiency of photogenerated electron-hole pairs.This study expands the potential applications of rare earth element doped g-C_(3)N_(4) in the photocatalytic selective oxidation of furfurans.

基于紫外光/臭氧化学改性-选择性化学镀的聚甲基丙烯酸甲酯表面区域金属化

研究以紫外光光化学反应为基础的在聚甲基丙烯酸甲酯(PMMA)表面区域选择性金属化的方法.通过对无臭氧紫外光、紫外光+臭氧(UV/O3)、臭氧对PMMA表面亲水化改性效果的对比,发现仅有UV/O3可有效地使PMMA表面亲水.表面红外光谱表明,UV/O3对PMMA表面协同作用的结果是在辐照区域生成了羧基等含氧活性基团.以此含氧活性基团为基础,经过胺化、氯金酸阴离子交换、NaBH4还原等表面反应,在UV/O3作用区域形成化学镀所必须的金纳米催化中心,再将PMMA浸入镀金、镀铜等化学镀浴中,即可实现PMMA表面的区域金属化.以打印的菲林片为原始掩膜,该方法分辨率可达50μm或更小.以该法制备了金和铜的薄膜微电极、金膜微电热器等金属微器件,并表征了它们的物理化学性能.

水溶性大豆多糖体外吸附Pb^(2+)的研究

以水溶性大豆多糖(SSPS)为吸附剂,改变pH、吸附时间、初始Pb^(2+)浓度、加入人体必需金属元素(Ca^(2+),Mg^(2+),Zn^(2+),Cu^(2+))探究其体外吸附Pb^(2+)的规律性质。结果表明:适宜吸附的pH范围为4~6;等温吸附曲线符合Langmuir单层吸附模型;动力学实验表明初始Pb^(2+)质量浓度为25 mg/L和50 mg/L时符合准一级动力学方程,初始Pb^(2+)质量浓度为100 mg/L时符合准二级动力学方程。大豆多糖对Pb^(2+)的选择性优于Zn^(2+)和Mg^(2+),其清除Pb^(2+)的同时可避免有益微量元素Zn^(2+)和Mg^(2+)的过度损失,是一种安全的Pb^(2+)吸附剂。

导电PEDOT膜的液相沉降聚合及应用研究——全加成线路板制作的可行性

为开发全加成PCB制作新工艺,将水解PI膜浸入H2O2和FeCl3溶液后再浸入EDOT溶液,研究EDOT原位聚合新方法,分析VUV辐射对PEDOT导电性的影响和在掩膜下制作导电图纹,以SEM揭示在导电PEDOT上电镀铜箔的形成.PI膜经H2O2和FeCl3溶液浸泡可引入mmol/m2量级的过氧基团和FeCl3,于EDOT溶液中与滞留层中的EDOT反应,形成PEDOT膜,使PI的表面电阻降至400Ω/□;VUV照射使PEDOT的导电性下降,可透过掩膜制作导电图纹;在电解池中导电PEDOT可传递电子使铜离子还原,沉积于导电PEDOT表面,形成针状晶核,再发育成枝晶、纺锤晶和连续铜箔,将导电图纹转化成铜线图纹.

大功率激光在3D打印中的应用

激光技术已应用于许多行业,其中在3D打印中激光技术主要用于金属粉末或陶瓷的烧结工艺过程中。本次论文论述了激光技术在3D打印中的作用和他们的发展趋势,3D打印中选择性激光烧结的基本工作机理以及其工艺,阐明了激光技术在3D打印中的地位无可替代,激光3D打印技术的作用不可估量。

Enhancing ethylene selectivity in MTO reaction by incorporating metal species in the cavity of SAPO-34 catalysts

The SAPO‐34 catalysts were modified with metal cations by different processes(conventional ion exchange(CIE),template‐assisted ion incorporation(TII)and alcoholic ion exchange(AIE)),systematically characterized by XRD,XRF,N2 adsorption‐desorption,UV‐VIS,H2‐TPR,EPR,SEM,EDX,XPS,NH3‐TPD,1H NMR and IGA,and applied in MTO reaction.The metal cations incorporation introduces extra diffusion hindrance by metallic species located in the cavity of SAPO‐34.In particular,the Zn cations‐modified SAPO‐34 catalysts exhibit core‐shell like structure,with Si‐rich and Zn‐rich sublayer near the external surface,which favors the coke deposition at the beginning of MTO reaction,exerts marked impact on the diffusion of the generated products with relatively large molecular size(e.g.propylene),and significantly increases the selectivity to ethylene and the ratio of ethylene to propene in the MTO reaction.

Adsorption behavior and mechanism of Hg(Ⅱ)on highly stable Zn-based metal organic frameworks

A novel adsorbent(MTZ-MOFs)was synthesized by a one-step reaction of zinc nitrate hexahydrate and 1-(2-dimethylaminoethyl)-1H-5-mercaptotetrazole to remove mercury from waste water.The results showed that MTZ-MOFs had excellent selectivity and repeatability for Hg(Ⅱ),the optimum pH was 3.0,the maximum adsorption capacity was 872.8 mg/g,and the process was a spontaneous exothermic reaction.The adsorption behavior was chemisorption,which conformed to the pseudo-second-order kinetic and Freundlich isothermal model.Moreover,the adsorption mechanism showed that the adsorption process mainly depended on ion exchange and chelation,and the synergistic action of S and N atoms played a key role.So,MTZ-MOFs were an efficient adsorbent for mercury ion removal.

Synergism of Pt nanoparticles and iron oxide support for chemoselective hydrogenation of nitroarenes under mild conditions

An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes.The conversion of nitrobenzene can reach 3170 molconv h^–1 molPt^–1 under mild conditions(30°C,5 bar),which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions.The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity,which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles.The unique surface properties ofα-Fe2O3 play an important role in the reaction process.It provides active sites for hydrogen spillover and reactant adsorption,and ultimately completes the hydrogenation of the nitro group on the catalyst surface.

Enhanced stability of highly-dispersed copper catalyst supported by hierarchically porous carbon for long term selective hydrogenation

Copper based catalysts have high potential for the substituent of noble-metal based catalysts as their high selectivity and moderate activity for selective hydrogenation reaction;however,achieving further high catalytic stability is very difficult.In this work,the carbonization process of Cu-based organic frameworks was explored for the synthesis of highly-dispersed Cu supported by hierarchically porous carbon with high catalytic performance for selective hydrogenation of 1,3-butadiene.The porous hierarchy of carbon support and the dispersion of copper nanoparticles can be precisely tuned by controlling the carbonization process.The resultant catalyst carbonized at 600°C exhibits a rather low reaction temperature at 75°C for 100%butadiene conversion with 100%selectivity to butenes,due to its reasonable porous hierarchy and highly-dispersed copper sites.More importantly,unprecedentedly stability of the corresponding Cu catalyst was firstly observed for selective 1,3-butadiene hydrogenation,with both 100%butadiene conversion and 100%butenes selectivity over 120 h of reaction at 75°C.This study verifies that a simply control the carbonization process of metal organic frameworks can be an effective way to obtain Cu-based catalysts with superior catalytic performance for selective hydrogenation reaction.

Development of New Generation Catalysts for Selective Hydrodesulfurization of FCC Naphtha

The influence of active metal components of catalyst, additives and catalyst preparation method on the reactivity of catalyst for selective hydrodesulfurization (HDS) of FCC naphtha was investigated, and the RSDS-21 catalyst with high HDS performance and the RSDS-22 catalyst with high selectivity were developed by RIPP. The composite loading of a new series of catalysts for selective HDS of FCC gasoline has demonstrated excellent desulfurization activity and selectivity and can under conventional hydrotreating conditions manufacture clean gasoline product meeting the national IV emission standard and the Euro V emission standard with less loss in antiknock index. The finalized new series of FCC catalysts upon being adopted for selective HDS of FCC naphtha have good adaptability to different feedstocks along with good stability.

Morphology evolution of acetic acid-modulated MIL-53(Fe)for efficient selective oxidation of H2S

MIL-53(Fe)was synthesized using a“modulator approach”that utilizes acetic acid(HAc)as an additive to control the size and morphology of the resulting crystals.We demonstrate that after activation under vaccum at 100℃,the MIL-53(Fe)functions well for H2S selective oxidation.The introduction of acetic acid in the presence of benzene-1,4-dicarboxylic acid(H2BDC)would result in a series of MIL-53(Fe)nanocrystals(denoted as MIL-53(Fe)-xH,x stands for the volume of added HAc with morphology evoluting from irregular particles to short hexagonal columns.The vacuum treatment facilitates the removal of acetate groups,thus generating Fe3+Lewis acid sites.Consequently,the resulted MIL-53(Fe)-xH exhibits good catalytic activity(98%H2S conversion and 92%sulfur selectivity)at moderate reaction temperatures(100–190℃).The MIL-53(Fe)-5H is superior to the traditional iron-based catalysts,showing stable performance in a test period of 55 h.

Nano-baskets of Calix[4]-l,3-crown in Emulsion Membranes for Selective Extraction of Alkali Metal Cations

Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclu sion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of diacid calix[4]-1,3-crowns-4,5 were synthesized, and their inclusion-extraction parameters were optimized including the calixcrown scaffold （4.4%, by mass） as the carrier/demulsifier, the commercial kero sene as diluent in membrane, sulphonic acid （0.2 mol.L-1） and ammonium carbonate （0.4 mol.L-1） as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed （300 r.min-1）, and initial solute concentration （100 mg.L-1）. The selectivity of membrane over more than ten interfering cations was examined and the re sults reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98%-99%.

ZIF-67 derived CoSx/NC catalysts for selective reduction of nitro compounds

Transition metal sulfides(TMSs)-based materials have been extensively investigated as effective non-noble catalysts for various applications.However,the exploration of TMSs-based catalysts for hydrogenation of nitro compounds is limited.Herein,CoSx/NC catalysts were prepared by solvothermal sulfurization of ZIF-67,followed by high-temperature annealing(300–600℃)under NH3 atmosphere.It was found that the structures and compositions of the as-prepared CoSx/NC can be readily tuned by varying the annealing temperature.Particularly,CoSx/NC-500,which possesses higher degree of S defects and larger specific surface areas,can achieve high conversion,selectivity and stability for catalytic reduction of nitro compounds into amines under mild reaction conditions.

Experimental and kinetic study of n-heptane isomerization on nanoporous Pt-(Re,Sn)/HZSM5-HMS catalysts

Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,temperature-programmed reduction of H2,temperature-programmed desorption of NH3,infrared spectroscopy of adsorbed pyridine,H2 chemisorption,nitrogen adsorption-desorption,scanning electron microscopy and thermogravimetric analysis were performed.Kinetics of n-C7 isomerization were investigated under various hydrogen and n-C7 pressures,and the effects of reaction conditions on catalytic performance were studied.The results showed that bi-and trimetallic catalysts exhibit better performance than monometallic catalysts for this reaction.For example,a maximum i-C7 selectivity（ 〉74%） and multibranched isomer selectivity（40%） were observed for Pt-Sn/HZSM5-HMS at 200 ℃.

Biosorption of Toxic Zn（ll） Ion from Water Using Ion Imprinted Interpenetrating Polymer Networks

Toxic Zn（II） ion imprinted interpenetrating polymer networks were synthesized for the selective sorption of Zn（ll） from aqueous solutions using a biopolymer alginic acid. The polymeric biosorbant was prepared using Zn（II） ion as template, acrylamide as functional monomer, cross linker NNMBA （N,N＇ Methylene-bis-acrylamide） and potassium persulphate as an initiator. The non-imprinted polymer networks were also prepared without use of the Zn（II） ion. The synthesized interpenetrating networks were characterized by various spectral techniques. Metal ion binding studies were carried out and the factors affecting binding were also optimized. Competitive sorption studies were investigated to determine the selectivity of Zn（II） ion imprinted interpenetrating polymer network. Zinc ion imprinted polymer networks showed good selectivity for the target ion.

Selective Separation of Au（lll） by the Column of Alginate Xerogel Microcapsules Enclosing TOA Extractant

The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.