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1.
以LiBH4和MnCl2为初始原料, 采用反应球磨法制备了LiMn(BH4)3/2LiCl复合物, 并系统地研究了该复合物的脱氢性能及含钛催化剂的掺杂对其脱氢性能的影响. 结果表明: LiMn(BH4)3/2LiCl复合物是由非晶态的LiMn(BH4)3和晶态的LiCl组成, 在135-190 °C分解, 分解反应的活化能为114.0 kJ·mol-1; LiMn(BH4)3/2LiCl复合物分解失重约7.0% (w). 组分分析表明除H2外, 释放的气体中还含有4.0% (摩尔分数, x)的B2H6. B2H6的生成是该复合物失重超过其理论储氢容量6.3% (w)的原因; 进一步研究发现, 含钛催化剂(TiF3、TiC、TiN和TiO2)中, 仅TiF3能够催化LiMn(BH4)3/2LiCl复合物的分解反应, 使其起始分解温度和分解反应活化能分别降低至125 °C和104.0 kJ·mol-1. 这主要归因于TiF3中的Ti原子取代了LiMn(BH4)3中的部分Li原子, 并在局域形成了易于分解的Ti(BH4)3.  相似文献   

2.
 本文用(Ph3P)2PdCl2为催化剂,合成了1,4-丁炔二醇(BD)与4,4-二乙炔联苯(DEBP)共聚物。对用不同比例的两种单体得到的共聚物测定了比重(d425、溶胀度(θD)、最良溶剂及相邻两交联点之间的平均分子量(Mc)。实验表明,在两种单体摩尔比中,DEBP用量越多,共聚物中泡状微孔越多,颜色越淡,溶胀度和比重越小,交联度越大;DEBP/BD(摩尔比)大于1/5时,共聚物的最良溶剂为苯,溶度参数为9.15卡0.5·cm-1.5,是1/10时,其最良溶剂为乙醇,溶度参数是12.7卡0.5·cm-1.5。对共聚物还做了红外光谱表征。  相似文献   

3.
通过碱性水热-离子交换法制备了Cu、N共掺杂TiO2纳米管(Cu/N-TNT),对其光催化重整甘油制备合成气性能进行了研究。结果表明,Cu/N-TNT具有富含氧空位(OV)的管状结构,N以Ti-N形式取代部分O形成杂质能级,Cu以Cu2+形式掺杂在催化剂晶格间隙和表面,Cu、N共掺杂促进TiO2表面电荷有效分离,有利于其光催化重整甘油制备合成气活性和选择性的提高。紫外光照射8 h时,掺Cu量为0.15%的Cu/N-TNT催化剂上CO和H2产量分别为7.3和8.5 mmol·g-1,是原始TiO2的9.1和70.8倍,nH2/nCO从0.52提高为1.18,nCO/nCO2从0.21提高至0.42。Cu/N-TNT表面N和OV为醛类脱羰和甲酸脱水生成CO提供反应活性位点,Cu作为浅势阱提高光生电子-空穴分离效率。光生空穴(h+)是光催化重整甘油制备合成气过程中的主要活性物种,大量羟基自由基(·OH)和超氧自由基(·O2-)会导致甘油过度氧化,使CO选择性降低。  相似文献   

4.
采用等温蒸发法研究了五元体系Li, K//, , -H2O 在288 K时的介稳相平衡关系, 测定了该五元体系在288 K条件下的介稳平衡的溶解度和溶液密度, 根据实验数据绘制了相应的介稳平衡相图和水图. 相平衡研究结果表明该五元体系介稳相平衡中有复盐K2SO4•Li2SO4生成, 其介稳相图(Li2CO3饱和)有4个共饱和点, 9条单变量曲线, 6个Li2CO3饱和的结晶区分别为LiBO2•8H2O, K2B4O7•4H2O, K2CO3•3/2H2O, K2SO4, Li2SO4•H2O和复盐 K2SO4•Li2SO4.  相似文献   

5.
本文报道了配合物[Cu2(EBTC)(H2O)2]·8H2O·DMF·DMSO(1, EBTC=1, 1′-乙炔基苯-3, 3′, 5, 5′-四羧酸根;DMF=N, N-二甲基甲酰胺;DMSO=二甲基亚砜)的合成、晶体结构和吸附性质。1拥有内径为0.85 nm和0.85 nm×2.15 nm的两种孔洞, 分别被6个和12个四羧酸根桥联的[Cu2(CO2)4]螺旋桨式结构围绕, 并被EBTC连接成三维超分子结构, 该结构拥有可容纳溶剂分子的一维孔道。1为(3, 4)-连接的fof(sqc1575)拓扑结构, 具有非常大的孔体积, 其值高达单位晶胞体积的72.8%。去除溶剂分子后的1a表现出永久孔性, 其Langmuir表面积为2844 m2·g-1, BET 表面积为1 852 m2·g-1。它对H2、CO2、CH4和C2H2具有可观的气体吸附量和相对较高的吸附焓。特别是, 在迄今所有已报道的孔性金属-有机材料中, 1a在273 K、1.0×105 Pa下, 表现出最高的乙炔吸附量(252 cm3·g-1)和很高的吸附焓(吸附量为1 mmol·g-1时的吸附焓为34.5 kJ·mol-1)。  相似文献   

6.
The layered zirconium [N-(phosphonomethyl)iminodiacetic acid-phosphate] Zr(HPO4)1.34[O3PCH2N-(CH2CO2H)2]0.66·H2O can only be prepared in the series of the zirconium phosphonate-phosphates Zr(HPO4)2-x[O3PCH2N(CH2CO2H)2]x·H2O (ZPPMIDA) by the reaction of zirconium oxychloride with phosphonic acid and H2O3PCH2N(CH2CO2H)2 in the designed x range of 0 < x < 2, which had been monitored by using the phosphorus integration value ratio of HPO42- and [O3PCH2N(CH2CO2H)2]2- group in the 31P MAS NMR spectra. After intercalation of n-butyl amine, the 31P chemical shift of HPO42- group at -8.0~-10.0 ppm moved to 6.0 ppm with a change of 14.0~16.0 ppm and that of [O3PCH2N(CH2CO2H)2]2- group at -29.1 ppm changed only 0.5 ppm. Due to the pillared effect of [O3PCH2N(CH2CO2H)2]2- groups on the interlayer spacing, intercalated amines such as n-butylamine, n-hexyl amine and n-octyl amine easily reacted with HPO42- group in ZPPMIDA (x=0.66) rather than that in α-ZrP, and carboxylic group (-CO2H) in ZPPMIDA (x=0.66).  相似文献   

7.
采用密度泛函理论(DFT)研究了NH3/KI、KI及无催化剂条件下, CO2与环氧丙烷(PO)合成碳酸丙烯酯(PC)的反应机理. 在B3LYP/6-311++G**基组水平上(I采用MIDIX基组)优化了反应过程中的反应物、中间体、过渡态和产物, 通过振动分析及内禀反应坐标(IRC)确定中间体和过渡态的真实性. 同时, 在相同基组水平应用自然键轨道(NBO)理论和分子中的原子(AIM)理论分析了这些化合物的轨道间相互作用和成键特征. 研究结果表明: 在无催化剂条件下非协同反应通道PO+CO2→M0a→TS0c→M0c→TS0c′→PC为最有利通道, 其活化能为200.65 kJ·mol-1; KI催化下活化能降低至187.40 kJ·mol-1, 反应速率较小; 在KI/NH3协同催化下, 除KI的催化作用外, NH3中的氢原子还能与CO2或PO中的氧原子形成氢键, 活化反应, 活化能降低至154.64 kJ·mol-1, 大幅度提高了PO与CO2环合生成产物PC的反应速率, 理论计算与实验结果一致.  相似文献   

8.
采用溶胶-凝胶法制备出偏硼酸锶(SrB2O4)光催化剂. 紫外光催化还原CO2合成CH4(在液相水中)的实验证明: SrB2O4催化剂的光催化活性略高于TiO2(P25). 利用X射线电子衍射谱(XRD)、傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、荧光(PL)光谱和紫外-可见(UV-Vis)漫反射吸收光谱等技术, 研究了SrB2O4 催化剂的晶体结构、形貌和能带结构. 结果表明: SrB2O4 的价带为2.07 V (vs normalhydrogen electrode (NHE)), 低于(H2O/H+)的氧化还原电位Eredoxo (0.82 V (vs NHE)); 而导带为-1.47 V (vsNHE), 高于(CO2/CH4)的氧化还原电位Eredoxo (-0.24 V (vs NHE)). 因此, SrB2O4催化剂可以有效地光催化还原CO2生成CH4. 与TiO2(P25)相比, SrB2O4催化剂具有相对较高导带, 光生电子的还原能力强于TiO2(P25), 更有利于CH4的生成, 从而决定了SrB2O4催化剂光催化还原CO2合成CH4具有较高的光催化活性.  相似文献   

9.
[RuCl2(PPh3)3],B10H102-与p-BrC6H4COOH在CH2Cl2中回流, 得到两个闭式十一顶钌十硼烷簇合物: [(PPh3)(p-BrC6H4CO2)2RuB10H8] (1) 和 [(PPh3)2Ru(PPh3)(p-BrC6H4CO2)RuB10H9] (2), 并进行了元素分析、红外光谱、1H核磁共振谱、13C核磁共振谱、X-射线单晶衍射表征. 簇合物1属于单斜晶系,空间群为C2/c, a = 2.569(4) nm, b=1.546(2) nm, c=1.927(3) nm, β=95.11(2)°, Z=8, V=7.622(21) nm3, Dc=1.533 Mg/m3, F(000)=3472, S=1.009, R=0.0418, wR=0.0775; 簇合物2属于三斜晶系, 空间群为P-1, a = 1.3142(3) nm, b=1.3761(3) nm, c=1.8503(4) nm, α=90.445(4)°, β=105.950(4)°, g=108.980(4)°, Z=2, V=3.0251(12) nm3, Dc=1.434Mg/m3, F(000)=1316, S=1.007, R=0.0464, wR=0.1175. 单晶结构分析表明, 两个簇合物的中心都具有一个闭式1:2:4:2:2堆砌结构的十一顶{RuB10}金属硼烷骨架, 硼笼开口处具有船式构象的环状的六个硼原子对Ru(1)原子呈h6船式配位. 在簇合物1中, 钌原子有三个簇外配体, 一个三苯基膦, 两个对溴苯甲酸根. 对溴苯甲酸根上另外的两个氧原子分别取代了B(2)和B(3)上的氢原子, 从而在簇合物的两侧形成两个对称的Ru-O-C-O-B五员环. 簇合物2是一个双金属钌硼烷簇合物, Ru(2)通过一个Ru-Ru键和两个{RuHmB}桥键与簇合物中心{RuB10}相连, 从而在簇外形成了一个变形的Ru(1)-Ru(2)-B(3)-B(6)四面体结构.  相似文献   

10.
在溶剂热条件下,以不对称三羧酸5-(6-羧酸-2-萘基)-间苯二羧酸(H3L)为配体合成了2个镉的金属-有机骨架化合物:{[Cd3L2(H2O)3]·6DMF}n(1)和{[Cd3L2(H2O)4]·3DMA}n(2)。通过X射线单晶衍射,粉末衍射,热重和红外光谱进行了结构表征。结构分析表明,12形成3,6-连接的三维结构,其拓扑符号分别为:(45.64.86)(43)2和(612.83)(63)2。此外,还对2个化合物进行了荧光分析。  相似文献   

11.
TPPAlCl-PPN+Cl binary catalyst (where TPPAlCl is 5,10,15,20-tetraphenylporphyrin aluminum chloride, PPN+Cl is bis[triphenylphosphine] iminium chloride, the molar ratio of TPPAlCl to PPN+Cl is 1 to 0.5) can initiate the effective one-pot/one-step ternary copolymerization of CO2, lactide and 4-vinyl-1-cyclohexene-1,2-epoxide, and the quaternary copolymerization of CO2, propylene oxide, lactide, 4-vinyl-1-cyclohexene-1,2-epoxide, to form multiblock poly(carbonate-co-lactide) products with pendant vinyl group. The ternary copolymerization product composes of polylactide (PLA) block and poy(vinylcyclohexylene carbonate) (PVCHC) block, and the quaternary copolymerization product composes of poy(propylene carbonate) (PPC) block, PLA block and PVCHC block, which are verified by 1H NMR, 13C NMR, 1H-1H cosy, hetero-nuclear multiple bond correlation, DTG, and Gel permeation chromatography analysis. The functionality and glass-transition temperature of the products can be easily adjusted by the copolymerization variables, such as the molar ratio of comonomers, copolymerization temperature, pressure of CO2, the concentration of the catalyst.  相似文献   

12.
A novel SalenCoIII (2,4‐dinitrophenoxy) (Salen = N,N'‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamino) and 1,10‐phenanthroline monohydrate catalyst system was designed and employed for the copolymerization of CO2 and propylene oxide (PO). The perfectly alternating copolymerization of CO2 and PO proceeds effectively under middle temperature and pressure to yield poly(propylene carbonate) with a high yield and a high number average molecular weight of polymer. The structure of polymer was characterized by the IR and NMR measurements. The perfectly alternating copolymer was confirmed. The MALDI‐TOF spectrum insinuates that the copolymerization of CO2 and PO was initiated by H2O. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

13.

High-molecular-weight polymers with different contents of propylene carbonate (PC), and trimethylene carbonate (TMC) units in the polymer chain were synthesized by the coordination anionic copolymerization of carbon dioxide, propylene oxide (PO), and TMC in supercritical carbon dioxide (scCO2). Zinc adipate (ZnAd) was used as a catalyst. The terpolymerization products were characterized by 1H and 13C NMR, IR spectroscopy, GPC, and DSC. The effect of the reaction conditions on the yield, composition, structure, and molecular weight and thermal characteristics of the terpolymers was studied. The phase behavior of the synthesized polymers and mixtures of polypropylene carbonate with polytrimethylene carbonate was examined.

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14.
The catalytic activities of tetraphenylporphinatoaluminum chloride (TPPAlCl) and its propylene oxide adduct (TPPAl(PO)2Cl) were investigated in detail together with a quarternary salt Et4NBr for the copolymerization of carbon dioxide and propylene oxide. In addition, for the components and starting raw materials of the catalyst systems, catalytic activities were examined for the copolymerization. The TPPAlCl catalyst delivered oligomers containing ether linkages to a large extent, regardless of its PO adduction. And cyclic propylene carbonate, as byproduct, was formed in a very small portion. Using the TPPAlCl coupled with Et4NBr as a catalyst system, the formation of ether linkages was reduced significantly in the copolymerization; however, the obtained oligomer still contained ether linkages of 25.0 mol % in the backbone. On the other hand, the formation of cyclic carbonate was increased to 22.4 mol % relative to the oligomer product. The results indicate that the salt, which was coupled with the TPPAlCl catalyst, plays a key role in reducing the formation of ether linkage in the oligomer and, however, in enhancing the formation of cyclic carbonate. Similar results were obtained for the copolymerization catalyzed by the TPPAl(PO)2Cl/Et4NBr system. That is, the formation of ether linkages was not restricted further by the PO adduction of the TPPAlCl component in the catalyst system. Only oligomers with a relatively high molecular weight were produced. This indicates that the PO adduction of the TPPAlCl component contributes highly to the initiation and propagation step in the oligomerization, consequently leading to a relatively high molecular weight oligomer. In contrast, the Et4NBr, as well as the Et2AlCl, produced only cyclic carbonate in a very low yield. Furthermore, tetraphenylporphine exhibited no catalytic activity, regardless of using together with Et4NBr. On the other hand, the Et2AlCl coupled with Et4NBr provided a low molecular weight oligomer having ether linkages of 92.3 mol % in addition to the cyclic carbonate. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3329–3336, 1999  相似文献   

15.
Synthetic routes to a series of new (salen)CoX (salen = N,N′-bis(salicylidene)-1,2-diaminoalkane; X = Br or pentafluorobenzoate (OBzF5)) species are described. Several of these complexes are active for the copolymerization of propylene oxide (PO) and CO2, yielding regioregular poly(propylene carbonate) (PPC) without the generation of propylene carbonate byproduct. Variation of the salen ligand, as well as the inclusion of organic-based ionic or Lewis basic cocatalysts, has dramatic effects on the resultant (salen) CoX catalytic activity. Highly active (R,R)-(salen- 1 )CoOBzF5 (salen- 1 = N,N′-bis(3,5- di-tert-butylsalicylidene)-1,2-diaminocyclohexane) catalysts with [Ph4P]Cl or [PPN]Y ([PPN] = bis(triphenylphosphine)iminium; Y = Cl or OBzF5) cocatalysts exhibited turnover frequencies up to 720 h1 for rac-PO/CO2 copolymerization, yielding PPC with greater than 90% head-to-tail connectivity. Additionally, the (R,R)-(salen- 1 )CoOBzF5/[PPN]Cl catalyst system demonstrated a krel of 9.7 for the enchainment of (S)- over (R)-PO when the copolymerization was carried out at low temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5182–5191, 2006  相似文献   

16.
Cobalt porphyrin complex (TPPCoIIIX) (TPP = 5, 10, 15, 20‐Tetraphenyl‐ porphyrin; X = halide) in combination with ionic organic ammonium salt was used for the regio‐specific copolymerization of propylene oxide and carbon dioxide. A turnover frequency of 188 h?1 was achieved after 5 h, and the byproduct propylene carbonate was successfully controlled to below 1%, where the obtained poly(propylene carbonate) (PPC) showed number average molecular weight (Mn) of 48 kg/mol, head‐to‐tail content of 93%, and carbonate linkage of over 99%. When the polymerization time was prolonged to 24 h, PPC with Mn over 115 kg/mol and head‐to‐tail linkage maintaining 90% was prepared, whose glass transition temperature reached 44.5 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5959–5967, 2008  相似文献   

17.
A new chromium(III) complex, bearing a bis-thioether-diphenolate [OSSO]-type ligand, was found to be an efficient catalyst in the copolymerization of CO2 and epoxides to achieve poly(propylene carbonate), poly(cyclohexene carbonate), poly(hexene carbonate) and poly(styrene carbonate), as well as poly(propylene carbonate)(cyclohexene carbonate) and poly(propylene carbonate)(hexene carbonate) terpolymers.  相似文献   

18.
Low‐molecular weight oligo(carbonate‐ether) diols are important raw materials for polyurethane formation, which with tunable carbonate unit content (CU) may endow new thermal and mechanical performances to polyurethane. Herein, facile synthesis of oligo(carbonate‐ether) diols with number average molecular weight (Mn) below 2000 g mol?1 and CU tunable between 40% and 75% are realized in high activity by immortal copolymerization of CO2/propylene oxide (PO) using zinc‐cobalt double metal cyanide complex (Zn‐Co‐DMCC) in the presence of sebacic acid (SA). Mn of the oligomer is in good linear relationship to the mole ratio of PO and SA (PO/SA) and hence can be precisely controlled by adjusting PO/SA. Besides, the molecular weight distribution is quite narrow due to the rapid reversible chain transfer in the immortal copolymerization. High pressure and low temperature are favorable for raising CU. In all the reactions, the weight fraction of propylene carbonate (WPC) can even be controlled as low as 2.0 wt %, and the catalytic activity of Zn‐Co‐DMCC is above 1.0 kgg?1 cat. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

19.
A series of ethylene, propylene homopolymerizations, and ethylene/propylene copolymerization catalyzed with rac‐Et(Ind)2ZrCl2/modified methylaluminoxane (MMAO) were conducted under the same conditions for different duration ranging from 2.5 to 30 min, and quenched with 2‐thiophenecarbonyl chloride to label a 2‐thiophenecarbonyl on each propagation chain end. The change of active center ratio ([C*]/[Zr]) with polymerization time in each polymerization system was determined. Changes of polymerization rate, molecular weight, isotacticity (for propylene homopolymerization) and copolymer composition with time were also studied. [C*]/[Zr] strongly depended on type of monomer, with the propylene homopolymerization system presented much lower [C*]/[Zr] (ca. 25%) than the ethylene homopolymerization and ethylene–propylene copolymerization systems. In the copolymerization system, [C*]/[Zr] increased continuously in the reaction process until a maximum value of 98.7% was reached, which was much higher than the maximum [C*]/[Zr] of ethylene homopolymerization (ca. 70%). The chain propagation rate constant (kp) of propylene polymerization is very close to that of ethylene polymerization, but the propylene insertion rate constant is much smaller than the ethylene insertion rate constant in the copolymerization system, meaning that the active centers in the homopolymerization system are different from those in the copolymerization system. Ethylene insertion rate constant in the copolymerization system was much higher than that in the ethylene homopolymerization in the first 10 min of reaction. A mechanistic model was proposed to explain the observed activation of ethylene polymerization by propylene addition. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 867–875  相似文献   

20.

The catalytic activity of the systems based on titanium(iv) alkoxides (Ti(OPri)4, Ti(OPri)2(OCH(CF3)2)2, and Ti(OCH(CF3)2)4) and mixtures of alkylaluminum chlorides (Et2AlCl or Et3Al2Cl3) with dibutylmagnesium in ethylene polymerization and ethylene copolymerization with propylene and 5-ethylidene-2-norbornene was studied. Ultrahigh-molecular-weight polyethylene with the molecular weight reaching 4.9 · 106 Da was found to be formed in the homopolymerization reaction, whereas copolymerization gives ter-copolymers containing propylene (up to 35 mol.%) and 5-ethylidene-2-norbornene (4.3 mol.%) units.

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