丙二酸锂-铑配合物的结构及催化性能研究

本文采用丙二酸锂为配体，与四羰基二氯二铑形成双齿配位的顺二羰基铑配合物，研究表明，在催化甲醇羰基化制乙酸的反应中，该配合物显示出高的活性和选择性。     

铑螯合物对苯乙烯氢甲酰化的催化作用

合成了螯合物二羰基邻氨基苯酚铑、二羰基(8-羟基喹啉)铑和二羰基亮氨酸铑,在常压、60℃下研究了其对苯乙烯氢甲酰化的催化作用.催化活性及选择性与氮氧螯合配体和外加膦配体结构有关,在双齿膦配体存在下,催化活性和选择性较高,膦铑比增大一般可使初活性降低,但转化率提高,而膦铑比对区域选择性影响很小.二羰基亮氨酸铑既表现出较好的活性和选择性,又可作为苯乙烯氢甲酰化手性催化剂,旋光产率9.5％.苯乙烯氢甲酰化的化学选择性均达100％.     

碳复合载体负载铑催化剂的制备及其对气相甲醇羰基合成乙酸的催化反应性能

碳复合载体负载铑催化剂的制备及其对气相甲醇羰基合成乙酸的催化反应性能李小宝王恩来田世忠蒋大智＊（中国科学院化学研究所，北京１０００８０）关键词碳复合载体，铑催化剂，甲醇，羰基合成，乙酸，乙酸甲酯，气相催化多孔炭负载催化剂在许多方面显示出独特的反应行为...     

有机溶剂萃取-分光光度法测定双三苯基磷羰基氯化铑中铑

铑的三苯基磷羰基络合物在工业上是低压羰基合成的催化剂,类似的络合物如双三苯基磷羰基氯化铑[RhCl(CO)(Ph_3P)_2]作为催化剂也得到人们的重     

高分子铑配合物（PYBRh）催化甲醇羰基化为乙酸和乙酸酐的动力学研究

采用２－乙烯吡啶－丁烯酮共聚物为配体，与四羰基二氯二铑形成顺二羰基铑（Ｉ）配合物（ＰＹＢＲｈ），用于催化甲醇羰基化制备乙酸和乙酸酐的反应动力学研究。结果表明，其对反应物甲醇和一氧化碳均为零级反应，在一定范围内，对高分子铑催化剂及助催化剂碘甲烷均为一级反应，极性溶剂的加入可以提高甲醇羰基化速度。通过实验结果计算了其反应活化能，活化熵和热焓研究证明其反应机理与小分子铑催化剂相似。     

RhCo双金属催化剂的研究 Ⅲ.Rh+Co/A1_2O_3上表面羰基氢化物及其动态行为

利用连续流动微反研究了Rh+Co/Al_2O_3催化剂的CO加氢反应.结果表明反应在220℃以上发生.反应活性随温度的升高和H_2/CO值的增加而增加.利用TP-IR动态方法研究了Rh+Co/Al_2_3上CO和H_2共吸附及其动态行为.结果表明在Rh+Co/Al_2O_3的孪生及线式中心上,CO和H_2室温共吸附时即有部分孪生及线式CO转化为相应的羰基氢化物.随温度的升高,剩余的孪生和线式CO继续向相应的羰基氢化物转化.而羰基氢化物则向多氢羰基氢化物转化.在到达反应温度之前,催化剂表面只存在羰基氢化物及相应的多氢羰基氢化物.在反应温度则导致产物CH_4生成.与CO加氢反应和CO歧化的吸附态研究结果相关联,作者认为在Rh+Co/Al_2O3上CO加氢生成CH_4是经由羰基氢化物-多氢羰基氢化物途径.     

RhCo双金属催化剂的研究III. Rh+Co/Al2O3上表面羰基氢化物及其动态行为

利用连续流动微反研究了Rh+Co/Al2O3催化剂的CO加氢反应, 结果表明反应在220℃以上发生, 反应活性随着温度的升高和H2/CO值的增加而增加。利用TP-IR动态方法研究了Rh+Co/Al2O3上CO和H2共吸附及其动态行为。结果表明在Rh+Co/Al2O3的孪生及线式中心上, CO和H2室温共吸附时即有部分孪生及线式CO转化为相应的羰基氢化物, 随着温度的升高, 剩余的孪生和线式CO继续向相应的羰基氢化物转化。而羰基氢化物则向多羰基氢化物转化。在到达反应温度之前, 催化剂表面只存在羰基氢化物及相应的多氢羰基氢化物。在反应温度则导致产物CH4生成。与CO加氢反应和CO歧化的吸附态研究结果相关联, 作者认为Rh+Co/Al2O3上CO加氢生成CH4是经由羰基氢化物-多氢羰基氢化物途径。     

RhCo双金属催化剂的研究III. Rh+Co/Al2O3上表面羰基氢化物及其动态行为

利用连续流动微反研究了Rh+Co/Al2O3催化剂的CO加氢反应, 结果表明反应在220℃以上发生, 反应活性随着温度的升高和H2/CO值的增加而增加。利用TP-IR动态方法研究了Rh+Co/Al2O3上CO和H2共吸附及其动态行为。结果表明在Rh+Co/Al2O3的孪生及线式中心上, CO和H2室温共吸附时即有部分孪生及线式CO转化为相应的羰基氢化物, 随着温度的升高, 剩余的孪生和线式CO继续向相应的羰基氢化物转化。而羰基氢化物则向多羰基氢化物转化。在到达反应温度之前, 催化剂表面只存在羰基氢化物及相应的多氢羰基氢化物。在反应温度则导致产物CH4生成。与CO加氢反应和CO歧化的吸附态研究结果相关联, 作者认为Rh+Co/Al2O3上CO加氢生成CH4是经由羰基氢化物-多氢羰基氢化物途径。     

RhCo双金属催化剂的研究Ⅵ.Rh_2Co_2/Al_2O_3上表面羰基氢化物及其动态行为

利用连续流动微反研究了Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３上的ＣＯ加氢反应．该反应在２００℃以上发生，反应活性随着温度的升高和Ｈ２／ＣＯ比的增大而增大．利用ＴＰＩＲ动态方法研究了Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３上ＣＯ和Ｈ２的共吸附及其动态行为．结果表明，在Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３的Ｒｈ上的孪生和桥式中心及Ｃｏ上的线式中心上，ＣＯ和Ｈ２室温共吸附时即有部分孪生、桥式ＣＯ及Ｃｏ上的线式ＣＯ转化为相应的羰基氢化物．随着温度的升高，剩余的孪生、桥式ＣＯ及Ｃｏ上的线式ＣＯ向羰基氢化物转化，而羰基氢化物又向多氢羰基氢化物转化．在ＣＯ加氢反应温度下，Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３的三种吸附中心上只存在多氢羰基氢化物．与ＣＯ加氢反应和ＣＯ歧化的吸附态动态研究结果相关联，可以认为在Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３上ＣＯ加氢生成ＣＨ４经由了羰基氢化物多氢羰基氢化物途径．     

顺二羰基(三齿N-配体)铑(Ⅰ)配合物的分子内取代反应

报道了3种不同结构的三齿N-配体以及与铑形成的顺二羰基配合物.研究表明,正方平面顺二羰基铑配合物在遇热条件下,其配体中未参与配位的授体N原子可取代它的一个端羰基而形成新的三齿配位结构.而在CO气氛下,三齿配位结构回到二齿配位状态.正方平面铑配合物的这一特殊分子内取代可逆反应过程,对于研究这类配合物结构、性能及催化作用均有重要的意义.非正方平面顺二羰基铑配合物则不发生上述分子内取代反应.利用IR和XPS对上述反应进行了表征.     

Rh2CO2/Al2O3上H2吸附及CO和H2共吸附

CO加氢反应机理一直是许多化学工作者感兴趣的课题．Rh催化剂因其优良的性能而被用于 CO加氢机理研     

烯烃氢甲酰化催化剂活性物种的原位1H NMR研究

The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pressurized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃. The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Ph-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.     

State of supported rhodium nanoparticles for methane catalytic partial oxidation (CPO): FT-IR studies

The effect of pretreatments as well as of rhodium precursor and of the support over the morphology of Rh nanoparticles were investigated by Fourier transform infrared (FT-IR) spectroscopy of adsorbed CO. Over a Rh/alumina catalyst, both metallic Rh particles, characterized by IR bands in the range 2070-2060 cm-1 and 1820-1850 cm-1, and highly dispersed rhodium species, characterized by symmetric and asymmetric stretching bands of RhI(CO)2 gem-dicarbonyl species, are present. Their relative amount changes following pretreatments with gaseous mixtures, representative of the catalytic partial oxidation (CPO) reaction process. The Rh metal particle fraction decreases with respect to the Rh highly dispersed fraction in the order CO approximately CO/H2 > CH4/H2O, CH4/O2 > CH4 > H2. The metal particle dimensions decrease in the order CH4/O2 > H2 > CH4/H2O > CO > CO/H2. Grafting from a carbonyl rhodium complex also increases the amount and the dimensions of Rh0 particles at the catalyst surface. Increasing the ratio (extended rhodium metal particles/highly dispersed Rh species) allows a shorter conditioning process. The surface reconstruction phenomena going on during catalytic activity are related to this effect.     

Thermodynamics of rhodium hydride reactions with CO, aldehydes, and olefins in water: organo-rhodium porphyrin bond dissociation free energies

Tetra(p-sulfonato-phenyl) porphyrin rhodium hydride ([(TSPP)Rh-D(D2O)](-4)) (1) reacts in water (D2O) with carbon monoxide, aldehydes, and olefins to produce metallo formyl, alpha-hydroxyalkyl, and alkyl complexes, respectively. The hydride complex (1) functions as a weak acid in D2O and partially dissociates into a rhodium(I) complex ([(TSPP)Rh(I)(D2O)](-5)) and a proton (D+). Fast substrate reactions of 1 in D2O compared to reactions of rhodium porphyrin hydride ((por)Rh-H) in benzene are ascribed to aqueous media promoting formation of ions and supporting ionic reaction pathways. The regioselectivity for addition of 1 to olefins is predominantly anti-Markovnikov in acidic D2O and exclusively anti-Markovnikov in basic D2O. The range of accessible equilibrium thermodynamic measurements for rhodium hydride substrate reactions is substantially increased in water compared to that in organic media through exploiting the hydrogen ion dependence for the equilibrium distribution of species in aqueous media. Thermodynamic measurements are reported for reactions of a rhodium porphyrin hydride in water with each of the substrates, including CO, H2CO, CH3CHO, CH2=CH2, and sets of aldehydes and olefins. Reactions of rhodium porphyrin hydrides with CO and aldehydes have nearly equal free-energy changes in water and benzene, but alkene reactions that form hydrophobic alkyl groups are substantially less favorable in water than in benzene. Bond dissociation free energies in water are derived from thermodynamic results for (TSPP)Rh-organo complexes in aqueous solution for Rh-CDO, Rh-CH(R)OD, and Rh-CH2CH(D)R units and are compared with related values determined in benzene.     

A new interpretation of the IR bands of supported Rh(I) monocarbonyl complexes

The characteristic CO vibrational frequency of supported monocarbonyl complexes Rh(I)CO, at 2014 and 1984 cm(-1) on dealuminated Y zeolite and alumina, respectively, is lower than the frequencies of both the symmetric and the antisymmetric CO normal modes of the corresponding stable supported Rh(I) dicarbonyls. The CO mode with a measured frequency between those of the symmetric and antisymmetric CO frequencies of the dicarbonyls, previously assigned to rhodium monocarbonyl, is reassigned to mixed carbonyl dihydrogen complexes Rh(H(2))(CO) or Rh(H)(2)(CO). This reassignment is based on a critical analysis of reported experimental data, supplemented by quantum chemical calculations.     

反应条件对固相合成负载羰基铑原子簇催化剂及其性能的影响

本文报告了由金属盐直接固相合成负载铑络合物或原子簇催化剂的新方法及IR谱表征。CO容易使表面吸附有水分子的RhCl_3/SiO_2还原并生成表面羰基物Rh~+-(CO)_2/SiO_2;CO、CO/H_2和CO/2H_2等不同还原气对表面络合物的生成没有影响。采用H_2还原只能得到金属Rh催化剂。水是重要影响因素,如果RhCl_3/SiO_2先抽空脱水,再用含水的CO还原,就会使Rh~+(CO)_2/SiO_2转化为Rh_6(CO)_(16)/SiO_2。此外,还考察了负载原子簇的CO加氢和热分解反应性能。采用CO还原RhCl_3/SiO_2制备的催化剂同负载原子簇催化剂的反应行为非常相近,而且比传统催化剂具有更高的反应活性。     

Infrared emission and theoretical study of carbon monoxide adsorbed on alumina-supported Rh, Ir, and Pt catalysts

The infrared emission spectra of CO adsorbed on alumina-supported 1, 3, and 5 wt % Rh, Ir, and Pt metal-containing catalysts were studied at 423 and 473 K. While CO is adsorbed in dicarbonyl (dimer), linearly (on-top) bonded and bridged carbonyl forms on rhodium and platinum, the dimer form is dominant on iridium. The relative intensity of Rh-CO and Ir-CO linear bands decrease with increasing temperature compared to the intensity of the dicarbonyl bands; the corresponding bands on Pt behave the opposite way. Two dicarbonyl and two linear Pt-CO bands were identified in the infrared spectra of Pt/Al(2)O(3) catalysts. The surface structure (kinked or planar Pt atoms), the dispersity of the metal, the temperature, and the quantity of adsorbed CO on the surfaces all have an effect on the fine structure of the Pt-CO stretching bands. The metal-carbon and CO stretching force constants were calculated for surface dicarbonyl, linearly bonded CO, and bridged carbonyl species. The metal-carbon stretching wavenumbers and force constants were predicted and compared between surface species and metal carbonyl complexes. The iridium-carbon bonds were found always stronger than the Rh-C and Pt-C ones in all surface species. The observed stretching wavenumbers and force constants seem to support the idea that CO and metal-carbon bonds are always stronger in metal carbonyl complexes than in adsorbed surface species. The distribution and mode of CO adsorption on surface metal sites can be effectively studied by means of infrared emission spectroscopy.     

Superoxo, peroxo, and hydroperoxo complexes formed from reactions of rhodium porphyrins with dioxygen: thermodynamics and kinetics

Rhodium(II) porphyrin complexes react with dioxygen to form terminal superoxo and bridged mu-peroxo complexes. Equilibrium constants for dioxygen complex formation with rhodium(II) tetramesitylporphyrin ((TMP)Rh*) and a m-xylyl-tethered dirhodium(II) diporphyrin complex (*Rh(m-xylyl)Rh*) are reported. (TMP)Rh-H reacts with oxygen to form a transient hydroperoxy complex ((TMP)Rh-OOH), which reacts on to form the rhodium(II) complex ((TMP)Rh*) and water. Kinetic studies for reactions of (TMP)Rh-H with O2 suggest a near concerted addition of dioxygen to the (TMP)Rh-H unit. Reactivity studies for mixtures of H2/O2 and CH4/O2 with the dirhodium(II) complex (*Rh(m-xylyl)Rh*) are reported.     

铑催化合成气制乙醇反应中CO断键途径的研究

利用程序升温表面反应─红外（ＴＰＳＲ－ＩＲ）动态技术考察ＣＯ吸附物种对氢的反应性能并检验表面反应生成的中间物，结果表明线式ＣＯ对氢的反应性能高于桥式ＣＯ，即线式ＣＯ更可能是活性吸附态；表面反应生成了ＨＣＯ、ＣＨ２等中间物．用键级守恒（ＢＯＣ）－Ｍｏｒｓｅ势方法计算比较了ＣＯ→ＣＨ２过程中各可能基元步骤在Ｒｈ（１１１）面上的反应活化能和反应热，结果表明ＣＯ经其部分氢化物种（如Ｈ２ＣＯ、ＨＣＯＨ）的氢解反应断裂Ｃ─Ｏ键在能量上最有利．根据这些实验结果，提出铑基催化剂上合成气转化反应主要按缔合式机理进行；ＣＯ的优势断键途径为先部分氢化，而后氢助断键．