Highly Active Sulfided NiPMo Hydrodesulfurization Catalyst Prepared from Keggin-type Phosphomolybdic Acid

A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.

Thermal Behaviour of Some New Polyoxometalate Complexes of Ciprofloxacin with Keggin-type Heteropoly Acids

Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.

Syntheses and Properties of Two Complexes Based on Keggin-type Polyoxometalate

Two unusual complexes [Cda（Do）4（H2O）2CI]（PW12O4O）＇2H2O （1） and [Aga（Do）6（PW12O40）][Ag（Do）2]2（PW12O4O）＇2H2O （2） were hydrothermally synthesized by the combination of two different metallic salts, Keggin-type polyoxometalate and 1,10-phen-5,6-dione （Do）, and characterized by elemental analyses, inductively coupled plasma analyses, infrared spectra, X-ray photoelectron spectroscopy, thermal gravimetry, photoluminescent spectra and single-crystal X-ray diffraction analyses. Crystal 1 is of monoclinic, space group P21/n with a = 12.383（3）, b = 18.326（4）, c = 16.437（3） A, β = 90.29（3）°, V = 3730.1（13） A3, Z = 2, CdzCasH32NsC1052PW12, Mr. = 4050.24, Dc = 3.604 g＇cm-3,μ（MoKa） = 19.145 mm1, F（000） = 3608, GOOF = 1.168, the final R = 0.0569 and wR = 0.0745 for 5715 observed reflections （1 〉 2σ（I））. Crystal 2 is of triclinic, space group Pi with a = 13.959（5）, b = 16.972（5）, c = 17.647（5）A, α = 85.970（5）, β = 81.353（5）, γ = 86.316（5）°, V = 4117（2） A3 Z = 1, Ag6C120H64N200102P2W24, Mr. = 8539.47, Dc = 3.444 g-cm-3,μ（MoKa） = 17.511 mm-1, F（000） = 3828, GOOF = 1.033, the final R = 0.0981 and wR = 0.1658 for 9906 observed reflections （I 〉 2σ（I））. Structural analyses show that complex 1 has a zero dimensional structure, which is further assembled into a one-dimensional ladder-like structure through hydrogen bonds. Complex 2 possesses a one-dimensional chain structure. Furthermore, solid-state luminescent spectra of complexes 1 and 2 indicate red and green fluorescent emission, respectively.

Rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)} with fast-responsive photochromism and switchable luminescence properties

Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-dimethylformamide) were synthesized by the conventional solution method.Structure analyses indicate that four compounds are isostructural and are all built from three [SiW_(12)O_(40)]^(4-) polyoxoanions and DMF ligands linked by RE^(3+).Compounds 1-4 are extremely sensitive to UV light and present excellent photochromic properties,in which the coloring and fading time of samples are both no more than 2 min,and the reversible coloring-fading process can be repeated for at least 10 cycles with little fatigue,suggesting that compounds 1-4 can be a series of fast-responsive and durable photochromic materials.Moreover,the solid-state photoluminescence spectra of compounds 3(Sm) and 4(Eu)display strong characteristic emissions of rare earth ions based on f-f transitions.Meanwhile,compound4(Eu) has a longer fluorescence lifetime up to 566.74 μs.Notably,co mpounds 3(Sm) and 4(Eu) exhibit the switchable luminescence behavior induced by photochromism,which allows them to be used as potential molecular switches.

Keggin-type H_4PVMo_(11)O_(40)-based catalysts for the isobutane selective oxidation

Cesium heteropolysalts Cs3PMo12O40 and HCs3PVMo11O40 were synthesized by modifying the preparation conditions in order to get materials with a much higher surface area than the original Keggin-type heteropolyacids(H3PMo12O40 and H4PVMo11O40).These solids were used as carriers for the dispersion of H4PVMo11O40 heteropolyacid by the incipient wetness impregnation technique.The textural and structural properties of supports and catalysts were examined by scanning electron microscopy,N2 adsorption-desorption isotherms and Raman spectroscopy.The supported catalysts were studied before and after red/ox pretreatments by X-ray photoelectron spectroscopy,which showed that both the surface composition and oxidized to reduced species ratio depend on the used carrier.The catalytic performances of these novel supported catalysts in the selective oxidation of isobutane to methacrylic acid and methacrolein were studied.The best catalytic properties were obtained when H4PVMo11O40 was supported on HCs3PVMo11O40.The isobutane conversion and yield of the desired oxygenates increased along the unsupported H4PVMo11O40<H4PVMo11O40/Cs3PMo12O40<H4PVMo11O40/HCs3PVMo11O40 series.

Effects of vanadium(V)-substitution on the oxidative properties of α-Keggin-type heteropolyanion clusters——progress in DFT theoretical studies

The redox properties of α-Keggin-type heteropolyanion clusters [XM12O40]n-(X = Si,P; M = Mo,W) mainly depend on their constituent outer metal-oxygen cages {M12O36}. They act as "reservoirs",through which the transfer and transition of electrons and protons may occur. At the atomic and molecular level,the redox properties of these clusters can be controlled and also tuned by modifying the metal M in the cages and the central heteroatom X of the clusters. Combined with relevant experimental results,this review summarizes our recent theoretical investigations of the effect of vanadium substitution on the redox properties of Keggin anion clusters. Theoretical modeling and calculation results showed that the oxidative ability of the modified species was increased by partial substitution of the cage M atoms of the Keggin clusters by vanadium atoms which have lower electronegativity. A linear correlation between the catalytic efficiency per vanadium atom and the microstructures of the vanadium(V)-substituted heteropolyanions [PVnMo12-nO40](3+n)-(n = 1-3) was established for the first time. This relationship may be suitable to interpret the catalytic behavior of the title compounds in the hydroxylation of benzene to phenol,and may also be used in understanding other reactions such as the oxidative dehydrogenation of isobutyric acid and the nitration of adamantine. The establishment of this nearly linear structure-property relationship may lay the foundations of understanding the behavior of the title compounds in homogeneous catalytic oxidation reactions,and may direct the design of future catalysts and the choice of other catalytic reactions.

Catalytic Aerobic Oxidation of Acetaldehyde over Keggin-type Molybdovanadophosphoric Acid/SBA-15 under Ambient Condition

Keggin-type molybdovanadophosphoric acids （HPA）, H4PMo11VO40 （1）, H5PMo10V2O40 （2） and H6PMo9V3O40 （3） were anchored onto γ-aminopropyltriethoxysilane （APTS） aminosilylated silica mesoporous SBA-15 through acid-base neutralization and the resulting HPA/APTS/SBA-15 were characterized by BET, TEM, XRD, ICP, FFIR and ^31p MAS NMR. The characterization results indicate that the Keggin-structure of these HPAs is preserved within the mesoporous silica host. The samples were tested for catalytic aerobic oxidation of acetaldehyde heterogeneously in liquid phase under ambient condition. The electrostatic force between heteropoly acid and amino groups grafted on the silica channel surface leads to strong immobilization of HPA inside SBA-15 which is against the leaching during the reaction. The good catalytic performance and easy recycle of these catalysts make them as potential environmental friendly catalysts for elimination of indoor air pollutants.

Keggin-type polycationic AlO_(4)Al_(12)(OH)_(24)H_(2)O_(12)^(7+)intercalated MoO_(3)composites for methyl orange adsorption

Molybdenum trioxide(MoO_(3))can be employed as an excellent host for intercalation due to its 2D lay-ered structure that connected by van der Waals interactions.Herein,a series of polyoxometalate-based MoO_(3) composites(Al_(13)@MoO_(3))were successfully prepared by interpolating the Keggin-type polycationic AlO_(4)Al_(12)(OH)_(24)H_(2)O_(12)^(7+)(Al_(13))into MoO_(3)gallery.These composites can be applied to rapidly adsorb the anionic dye methyl orange(MO)through strong electrostatic interactions lead to compact and sta-ble gathering in the surrounding of the numerous charged Al_(13).Adsorption behaviors of composites with the different amount of Al_(13) were determined,these results revealed that Al_(13)-3.34%@MoO_(3)exhibited the most remarkable adsorption capacity.More importantly,the composite maintains superior adsorption capacity for five consecutive adsorption/desorption cycles,suggesting that Al_(13)@MoO_(3)can be an efficient and durable adsorbent.

PW_(11)M@Cu_(3)(BTC)_(2)杂化物的合成及燃料油深度脱硫活性

合成了过渡金属单取代的Keggin型钨磷酸盐(PW_(11)M,M=Ti^(4+),Cr^(3+),Mn^(2+),Fe^(3+),Co^(2+),Ni^(2+),Cu^(2+)和Zn^(2+)),并将其担载在Cu_(3)(BTC)_(2)金属有机框架中,合成了一系列过渡金属取代的多酸基金属有机框架杂化物[PW_(11)M@Cu_(3)(BTC)_(2)].通过单晶X射线衍射分析、元素分析(ICP)、粉末X射线衍射(PXRD)、热重分析(TG)和氮气吸附-脱附实验等确定了杂化物的组成、结构和多孔性.该类杂化材料对燃料油中二苯并噻吩具有良好的吸附作用,并催化其快速氧化为二苯并噻吩砜,实现了以氧气为氧化剂的燃料油深度脱硫.

一种多功能性Keggin型多酸基配合物的合成、结构及性能

设计合成一种基于Keggin型多酸的无机-有机杂化配合物,利用水热原位合成法获得[SiW_(12)O_(40)][Ag(bpy)_(2)]4·H_(2)O(1),(bpy=2,2′-联吡啶).该配合物中的bpy由2,2′-联吡啶-6,6′-二羧酸原位脱羧得到.利用单晶X射线衍射、元素分析、红外光谱及热重分析对该配合物的结构进行表征,并研究其荧光、光催化降解有机染料、电化学性质及抑菌性能.

六元瓜环和Keggin型杂多酸自组装及催化合成乙酸乙酯

杂多酸(HPAs)是一类用途广泛的多功能材料,在酯化反应中具有优异的催化剂性能。由于HPAs良好的溶解性,作为均相催化剂使用时,不易与产物分离、难以回收和重复利用。利用六元瓜环(Q[6])与Keggin型杂多酸的自组装作用,制备了系列难溶性Q[6]-HPAs催化剂。该类催化剂具有性质稳定、比表面积大、回收率高,可循环利用等特点,在乙酸乙酯(EA)合成中表现出较高的催化活性和循环利用率,具有潜在的应用前景。

含有甘氨酸的Keggin型杂多蓝的合成和抗艾滋病毒(HIV-1)活性研究

采用控制电位电解方法 ,制得 8种含有甘氨酸的Keggin型钨系杂多蓝配合物 .通过IR ,UV vis ,1 HNMR ,1 83 WNMR ,XPS等方法对其结构进行了表征 .这类化合物具有较强的抗碱解能力 .在MT 4细胞内 ,对合成化合物进行了抗艾滋病毒(HIV 1)活性及毒性测定 ,发现该类化合物的抗艾滋病毒 (HIV 1)活性随着还原电子数增多有增强的趋势 ,其中含有甘氨酸的十二钨锗酸 4电子杂多蓝 (代号HPBG 110 )有较高的治疗指数 (TI) .初步的试验结果表明 :该类化合物的抗HIV 1活性作用是在病毒感染早期 ,通过抑制艾滋病毒 (HIV 1)

柱撑粘土矿物材料的晶体结构和晶体化学特征

以铝基柱撑粘土矿物和钛基柱撑粘土矿物为例 ,讨论了柱撑粘土矿物材料的晶体结构和晶体化学特点。Al多核笼状阳离子基团的结构形式为 1∶ 12 Keggin型离子 ,Ti多核笼状阳离子基团的结构形式为 2∶ 18Dawson型离子 ,两类笼状阳离子的直径均在 1nm左右 ,前者的高度约为 0 .9nm,后者的高度约为 1.4nm。经与粘土矿物层间阳离子交换后 ,择位固定在粘土矿物层间。由于多核笼状阳离子与粘土矿物硅氧四面体层之间形成了较强的化学键 ,其具有不可交换性。铝基柱撑粘土和钛基柱撑粘土的层间孔道分别为 1.2 nm× 1.2 nm× 1.2 nm和 0 .5 2 nm× 0 .5 2 nm× 1.6 0 nm。柱撑粘土矿物材料有很好的化学稳定性和耐热性 ,且又具有一定的层间化学活性 ,可用于催化剂载体 ,由于它又具有选择性吸附能力 。

Keggin型磷钼矾杂多化合物在氧化羰基化合成碳酸二苯酯中的应用

采用酸化乙醚萃取法制备了Keggin型磷钼矾杂多酸及其盐,并采用FT-IR和BET对磷钼矾杂多酸进行了表征。考察了磷钼矾杂多化合物在苯酚氧化羰基化合成碳酸二苯酯反应中的性能。结果表明,高含钒量的杂多酸具有更好的催化活性,它们的活性顺序为:H6PMo9V3O40>H5PMo10V2O40>H4PMo11VO40。用不同价态的金属阳离子取代H6PMo9V3O40中的氢离子后,CeH3PMo9V3O40表现出了最好的性能,DPC的收率达6.7%;当进一步用VO2+取代了CeH3PMo9V3O40中的氢离子后,Ce[VO]1.5PMo9V3O40的性能更好,碳酸二苯酯的收率达10.2%。

Keggin结构阳离子[AlO_4Al_(12)(OH)_(24)(H_2O)_(12)]^(7+)与杂多阴离子构筑的新型无机纳米簇凝胶

The novel class of inorganic nanoclusters, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[SiW\-\{11\}O\-\{39\}CoCl\]\}\511H\-2O, \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\{\[P\-2W\-\{18\}O\-\{62\}\]\}Cl\533H\-2O and \{\[AlO\-4Al\-\{12\}(OH)\-\{24\}(H\-2O)\-\{12\}\]\}\-2\[NaP\-5W\-\{30\}O\-\{110\}\]\524H\-2O, consisting of Keggin cations and heteropolyoxometalates, has been synthesized and characterized by ICP, IR and NMR. It is proved that the intrinsic identities of Keggin cation and heteropolyanions of the clusters are preserved within the gels.

Keggin杂多阴离子电子结构和物化性质与中心原子的关系

使用密度泛函理论中的离散变分方法(DFr-DVM),以(XMo12O40)n-(X=B,Al,Si,Ge,P,As,S)为例计算了七个Keg-n杂多阴离子的电子结构,讨论了中心原子对Keggin阴离子的电子结构、稳定性、氧化还原性和酸性的关系.根据计算结果,给出稳定性、氧化还原性强弱顺序,计算给出结果与实验一致.

Keggin型P-Mo-V杂多酸催化合成苯甲酸正丁酯

以苯甲酸和正丁醇为原料,甲苯为带水剂,用自制的Keggin型钼钒磷杂多酸为催化剂,合成了苯甲酸正丁酯。探讨了催化剂用量、原料配比、带水剂用量和反应时间对产品收率的影响,并用多种手段对产品做了检测分析。结果表明,合成该酯的最佳工艺条件为:n(正丁醇)/n(苯甲酸)=3,催化剂用量为反应物料总质量的12%,甲苯做带水剂,反应温度控制在110～115℃,反应时间2h。在此条件下,酯收率可达80 49%。

三维结构多金属氧酸盐Ag_4H_3PTi_2W_(10)O_(40)·16H_2O的合成与表征

以Keggin型钛取代钨磷酸钾和醋酸银为反应物合成了1个新的多金属氧酸盐Ag4H3PTi2W10O40.16H2O(1),通过X射线单晶衍射分析确定了其晶体结构,通过ICP分析和热重分析确定了其组成,通过红外光谱和固体漫反射光谱表征了其性质.单晶结构分析表明,化合物1属于四方晶系,I4/m空间群,晶胞参数a=b=1.39905(13)nm,c=1.14358(18)nm,V=2.2384(5)nm3,Z=2,R1=0.0550,wR2=0.1590.化合物1中的Ag+均为六配位,每个Ag+同时与3个多阴离子上的2个端氧和4个桥氧配位形成{AgO6}单元,这些{AgO6}将该多阴离子连接成三维网络结构.

PW_(11)O_(39)Co(Ⅱ)(H_2O)^(5-)的均相及异相体系可见光催化性能研究

以模型污染物罗丹明B(RhB)的光降解为探针,评估了Keggin型钴取代杂多阴离子PW11O39Co髤(H2O)5-(PW11Co)及其异相体系PW11Co/D301R的可见光催化活性,提出了光催化反应的机理,同时考察了催化剂用量、溶液酸度以及溶液中PW11Co和RhB的相互作用对RhB可见光催化降解速率的影响。实验结果表明,PW11Co均相体系及其异相体系PW11Co/D301R对RhB的可见光降解均有较高的光催化活性,但PW11Co/D301R的光催化活性更高。导致RhB降解的主要是羟基自由基。与PW11Co均相体系相比,在PW11Co/D301R异相体系中由于PW11Co与RhB的配位作用大为减弱,同时D301R对RhB具有富集作用,因而大大提高了RhB的光催化降解速率。

K_4H_(2.2)PTi_(1.60)W_(10.40)4O_(40)·13H_2O的合成、表征、晶体结构及抗菌活性

Na2WO4·2H2O与NaH2PO4及TiCl4在常规条件下反应合成Keggin型钨钛磷酸钾K4H2.2PTi1.60W10.40O40·13H2O(1),并通过元素分析,IR,UV,X-ray单晶衍射表征。化合物1晶体属于四方晶系,P4/mnc空间群,a=1.4158(2)nm,b=1.4158(2)nm,c=1.2449(3)nm,V=2.4955(7)nm3,Z=2,R1=0.0583,wR2=0.1447。该晶体沿a轴方向晶胞堆积有一截面为0.72nm×0.62nm的孔道,水分子填充在孔道内。183WNMR谱表明多阴离子在溶液中主要以C2对称性的异构体存在。该化合物对绿脓杆菌和β-溶血链球菌有较强的抑制活性。