钾改性氧化铝基羰基硫水解催化剂及其失活机理

天然气、油田伴生气、高炉煤气等化工生产过程中伴生COS气体,不仅会腐蚀管道和毒害催化剂,还会严重污染环境并危害人类健康。COS催化水解反应可在温和条件下高效的将COS脱除,是最具应用前景的COS脱除技术之一。碱金属元素因其具有独特的电子供体性质、表面碱性和静电吸附等特性,常被用作助催化剂以提高Al₂O₃的COS催化水解性能。近年来,以钾为助剂改性的Al₂O₃催化剂(K₂CO₃/Al₂O₃)在COS催化水解反应中得到广泛的应用,但由于负载在Al₂O₃上的K物种的组成复杂,目前研究者对K₂CO₃/Al₂O₃催化剂上COS水解机理的理解仍存在一定的困惑和争议。本论文通过湿法浸渍法合成出一系列钾盐和钠盐改性的Al₂O₃催化剂,并利用各类先进的表征技术对这些催化剂进行分析。活性测试表明,以K₂CO₃、K₂C₂O₄、NaHCO₃、Na₂CO₃和NaC₂O₄改性Al₂O₃催化剂均有助于COS的水解。其中K₂CO₃/Al₂O₃拥有最佳的COS水解性能,连续运行20 h后其COS转化率仍高于~93%,远远优于未改性的Al₂O₃ (~58%)。我们利用原位红外光谱和X射线光电子能谱探明了反应过程中催化剂的化学结构特征,阐明了H₂O分子在K₂CO₃/Al₂O₃上的水解作用机制。原位红外表明COS在K₂CO₃/Al₂O₃上的水解过程中形成了硫代碳酸氢盐中间产物。X射线光电子能谱表征证明催化剂的失活主要是因为催化剂表面积累了硫酸盐和单质硫。此外,我们还研究了水蒸气含量对COS水解性能的影响,研究发现,由于H₂O和COS分子在催化剂表面存在竞争吸附,过量的H₂O会引起催化活性的下降。上述研究表明,K₂CO₃/Al₂O₃催化剂上COS水解性能的提高主要是形成了HO-Al-O-K界面活性位。更为重要的是,所制备的催化剂都是在模拟工业工况条件下进行的,这为后续的工业应用提供了宝贵理论指导。本工作为理解助剂钾在Al₂O₃催化剂上COS水解活性的增强提供了新的见解,这为未来设计稳定高效的COS水解催化剂打开了新的发展方向。     

Synthesis and Crystal Structure of a Novel Zinc Phosphonate Compound： [Zn（phen）（m-OOCC6H4PO3H）]

A novel zinc（H） metal phosphonate compound [Zn（phen）（m-OOCC6H4PO3H）] 1 （phen = phenanthroline） has been synthesized under hydrothermal conditions. Single-crystal X-ray structure analysis reveals that compound 1 belongs to the triclinic system, space group P1 with a = 9.3356（19）, b = 10.203（2）,c = 10.743（2）A,α = 76.3030（70）, β= 69.2317（51）, y = 84.3833（74）°,V = 929.4（3） ,A3, Z = 2, C2OH15N2O5PZn, Mr = 459.68, Dc = 1.643 g/cm^3,μ= 1.444, mm^-1, F（000） = 468, the final R = 0.0330 and wR = 0.0848. In the structure, the central ion Zn（H） is five-coordinated, linking three O atoms with one from carboxyl and the other two from phosphonyl group. The remained two coordinate sites were occupied by two N atoms from one phen molecule to form the asymmetric unit. Then every two adjacent asymmetric units are bridged by the O atoms from phosphonate group and carboxyl to give rise to a 1D chain along the b axis. These chains are constructed by weak π-π stacking interactions and C-H…π interactions to generate a 3D supramolecular framework.     

Synthesis and Structural Characterization of a New Polyoxovanadium Borate: (H_3NCH_2CH_2NH_3)_4[(VO)_6(B_(10)O_(22))_2]·(H_3O)_7

1 INTRODUCTION Transition metal oxide clusters and their deriva- tives offer an unmatched variety of structural motifs and wide ranging applications in several areas, such as analytical chemistry, materials science and cataly- sis, nanotechnology, chemical sensing, environmental decontamination, biochemical and geochemical pro- cesses, and medicine[1～3]. Polyoxovanadates or vana- dium oxide clusters constitute an important subclass of polyoxometalates and have been studied exten- sively.…     

Two Zinc（Ⅱ） Carboxyarylphosphonates with Unusual Polynuclear Zn（Ⅱ） Units：Syntheses and Crystal Structures

[Zn2(PCP)(phen)(H2O)F]n 1 and {[Zn3(MCP)2(phen)2(H2O)]·2.5H2O}n 2(PCP = p-O2C(C6H4)PO33-,MCP = m-O2C(C6H4)PO33- and phen = phenanthroline) were obtained by hydrothermal synthesis and characterized by X-ray single-crystal diffraction.Compound 1 crystallizes in the monoclinic P21/c space group with a = 7.908(2),b = 20.254(3),c = 13.477(2) ,β = 107.76(3)°,V = 2055.7(8) 3,Z = 4,C20H16FN2O6PZn2,Mr = 561.10,Dc = 1.813 g/cm3,μ = 2.463 mm-1,F(000) = 1128,the final R = 0.0340 and wR = 0.0794.Compound 2 crystallizes in the monoclinic P21/n space group with a = 15.629(3),b = 18.141(4),c = 17.723(7) ,β = 121.89(2)°,V = 4267(2) 3,Z = 4,C40H31N4O13.5P2Zn3,Mr = 1041.70,Dc = 1.620 g/cm3,μ = 1.818 mm-1,F(000) = 2108,the final R = 0.0669 and wR = 0.1775.In compound 1,the tetranuclear Zn4 units are linked together by μ4-PCP3- to build 2D(4,4) layers,which are further interconnected through the μ2-bridging fluorion into a 3D framework with 1D phen ligands-filled channels.As for the 3D supramolecular framework of 2,the novel hexanuclear Zn6 units with "chair" conformation are extended by the moieties of μ4-MCP3- ligand to a 2D(4,4) layer on the bc plane,which is viewed as the 2-folded layers in 1.In both compounds,the structures are stabilized by hydrogen bonding interactions and π-π stacking interactions between the phen rings.Additionally,FT-IR spectroscopy and the fluorescent properties are discussed.     

Synthesis and Crystal Structure of a Novel 1D Coordination Polymer:[Pr(BYBA)_3(H_2O)_2]·[Pr(BYBA)_3(H_2O)]

The novel coordination polymer [Pr(BYBA)3(H2O)2]·[Pr(BYBA)3(H2O)] (BYBAH=2-benzoylbenzoic acid) was yielded by hydrothermal synthesis,determined by single-crystal X-ray diffraction,and characterized by FT-IR and UV-Vis spectra. The crystal crystallizes in the triclinic system,space group P1 with a=9.112(3),b=14.644(5),c=27.076(11),α=84.223(3),β= 87.816(4),γ=88.902(4)o,V=3592(2)3,C84H60O21Pr2,Mr=1687.14,Z=2,F(000)=1700,Dc= 1.560 g/cm3,μ=1.419 mm-1,the final R=0.0485 and wR=0.1258 for 13035 observed reflections with I > 2σ(I). The compound contains two different building units,[Pr2(BYBA)6(H2O)4] and [Pr2(BYBA)6(H2O)2]. It is noticeable that [Pr2(BYBA)6(H2O)4] is an isolated binuclear building block,in which the Pr3+ ion centers are both located in an eight-coordinated environment. However,in [Pr2(BYBA)6(H2O)2] the Pr3+ ion centers are located in a nine-coordinated environment and connected by BYBA ligands to form 1D chains.     

高比表面积铝土矿载体的制备及在CO氧化反应中的应用

采用水热法,对天然铝土矿进行改性,获得高比表面积的铝土矿载体(Bauxite)。用等体积浸渍法制备了不同Pt含量的Pt/bauxite和1.0%Pt/Al2O3催化剂,以CO氧化为探针反应,考察了催化剂性能。采用XRF、XRD、低温N2-物理吸附、H2-TPR以及CO-TPD等对载体和催化剂样品进行表征。结果表明:Pt/bauxite催化剂具有优异的CO氧化性能,特别是当反应温度为200℃时,催化剂1.0%Pt/bauxite的CO转化率为93.4%,而1.0%Pt/Al2O3CO转化率仅为9.4%。其原因是铝土矿含有的Fe2O3是CO氧化反应的催化剂,且Fe2O3与负载的Pt之间发生了相互作用,降低了Pt和Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的CO氧化反应性能。     

Synthesis,Spectroscopic Properties and Crystal Structure of (C4N2H12)2Zr(C2O4)4·H2O

The title compound (C4N2H12)2Zr(C2O4)4·H2O 1 was synthesized by the reaction of ZrOCl2·8H2O, H2C2O4·2H2O and piperazinium in aqueous solution. Single-crystal X-ray analysis has revealed that compound 1 (C16H26N4O17Zr, Mr = 637.63) crystallizes in the monoclinic system, space group P21/c with a = 9.0425(3), b = 13.3844(3), c = 19.1191(5)A, β = 98.365(1)o, V = 2289.34(11) A3, Z = 4, Dc = 1.850 g/cm3, F(000) = 1304, μ = 0.577 mm-1, the final R = 0.0240 and wR = 0.0628 for 4386 observed reflections with I > 2σ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Zr(C2O4)4]4- anion and two protonated piperazinium cations. The anions are linked through hydrogen bonds of piperazinium. FT-IR and Raman spectra clearly show the existence of oxalate groups in the crystal lattice.     

改性铝土矿载体负载Ru催化剂上的水煤气变换制氢

采用水热法对天然铝土矿进行改性,获得高比表面积的铝土矿(bauxite)载体.用等体积浸渍法制备了Ru含量为1.0%-4.0%(质量分数,下同)的Ru/bauxite催化剂和Ru含量为2.0%的Ru/Al2O3催化剂,以水煤气变换反应为探针反应,考察了催化剂性能.利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、低温N2物理吸附、H2程序升温还原(H2-TPR)以及CO程序升温脱附(CO-TPD)等对载体和催化剂样品进行表征.结果表明,不同Ru含量的Ru/bauxite催化剂具有优异的水煤气变换制氢性能,优于Ru/Al2O3催化剂.其原因是铝土矿本身含有的Fe2O3与负载的Ru之间发生了相互作用,降低了Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的水煤气变换反应性能.     

碳纳米管-氧化铝:高抗硫及再生性能的Pt基催化剂载体及在NO_x还原反应中的应用(英文)

通过乙炔在Al2O3上的分解制备碳纳米管-氧化铝(Al2O3-CNTs)载体.采用浸渍法,分别制备了Pt/Ba/Al2O3-CNTs和Pt/Ba/Al2O3催化剂.利用XRD,SEM,TEM,低温N2物理吸附,XPS和in-situ DRIFTS等手段对催化剂的物化性质进行了表征.结果表明,在SO2存在下的NOx还原反应中,Pt/Ba/Al2O3-CNTs比Pt/Ba/Al2O3具有更高的抗SO2性能和再生性能.In-situ DRIFTS表明SO2的存在对NOx储存还原的途径没有影响.     

乙酸调控MIL-53(Fe)的形貌演变及其高效选择性氧化H2S性能

硫化氢(H2S)广泛存在于以煤、石油和天然气等为原料的化工生产过程中,不仅腐蚀管道和设备,而且还会对健康和环境造成危害.因此,高效脱除H2S已成为工业废气减排的重点.在各种方法中,H2S选择性氧化技术(H2S+(1/2)O2→(1/n)Sn+H2O)由于具有设备需求低、反应不受热力学平衡限制、理论转化率可达100%等优点展现出了巨大的应用前景.实现这一过程的关键在于发展高效稳定的催化剂.作为一类新兴的多孔材料,金属-有机骨架材料(MOFs)由于其独特的结构和性质吸引了广泛的研究兴趣.与传统的脱硫材料相比,MOFs的优势主要体现在:1)高度分散的金属原子可作为催化活性中心;2)超高比表面积和规则的孔结构有利于反应物与活性位点之间的接触;3)结构可调变性高,通过在合成过程中有目的地引入配体或调控剂可产生额外的活性位点,满足特定催化的需求.基于以上特点可知,MOFs是一类有潜力的催化剂,但目前将其应用于H2S选择性氧化领域的研究尚处于起步阶段.本文以典型的铁基MOFs MIL-53(Fe)为研究对象,在制备MIL-53(Fe)过程中添加乙酸(HAc)作为调控剂,通过控制HAc的量,得到一系列具有不同形貌的MIL-53(Fe)-xH样品,并将其应用于H2S选择性氧化反应.SEM结果表明,在MIL-53(Fe)的合成过程中引入乙酸可以显著影响样品的形貌和尺寸.活化前后样品的XRD结果表明,HAc具有与对苯二甲酸(H2BDC)相似羧基基团,二者均可与Fe–O团簇配位.此外,TG-DSC结果证实,随着HAc加入量的提高,与Fe^3+形成配位的HAc/H2BDC比值随之增加.FT-IR和Raman结果进一步证明HAc成功地配位到MIL-53(Fe)的框架中,并且参与配位的HAc可通过真空活化移除从而暴露出Fe^3+不饱和位点.H2S选择性氧化测试表明,MIL-53(Fe)-xH的脱硫活性随着HAc含量的提高先增加然后降低,其中MIL-53(Fe)-5H活性最优.此外,MIL-53(Fe)-5H催化剂在连续运行55 h后仍能保持100%H2S转化率和86%硫选择性,性能远优于传统的Fe2O3催化剂.吡啶原位红外光谱结果表明,HAc的引入可以产生额外的Lewis酸性位点(LAS),LAS含量的不同是造成催化剂活性差异的主要原因.