丁烯氧化脱氢制丁二烯反应中丁烯转化的动力学初步考察

在10毫升催化床的小型装置上进行了丁烯转化动力学的初步考察,以期求出丁烯在L-2605型催化剂上氧化脱氢总包反应的似活化能与反应速度方程. 在排除线速度干扰的情况下,考察了催化剂粒度(粒度平均半径为0.025—0.16厘米)对丁烯氧化盼氢反应中丁烯转化速度的影响.在排除外扩散与内扩散干扰的条件下,进行了反应温度(350—530℃)及各反应物分压(丁烯、丁二烯、氧及水蒸气)对丁烯转化速度的影响的考察.求得丁烯在L-2605型催化剂上氧化脱氢的总包反应似活化能为20.7千卡/克分子.在试验的反应温度范围内,丁烯氧化脱氢中丁烯转化速度方程可表示如r=kp_u,式中r为丁烯转化速度,克分子/小时·克催化剂;k为速度常数,克分子/小时·克催化剂·大气压;p_u为丁烯分压,大气压.     

异戊烯与甲醇成醚反应机理的量子化学研究

对2-甲基-1-丁烯、2-甲基-2-丁烯与甲醇反应生成甲基叔戊基醚的反应历程进行了量子化学研究, 结果表明, 反应过程包括两个基元步骤: 2-甲基-1-丁烯和2-甲基-2-丁烯与氢离子作用生成碳正离子, 活化能分别为E1=2.26 kJ/mol, E2=7.72 kJ/mol; 甲醇与叔碳正离子反应成醚, 活化能为E3=1.29 kJ/mol, 碳正离子的生成是反应的速控步骤. 2-甲基-1-丁烯与2-甲基-2-丁烯相互转化的异构化活化能分别为E'1=4.40 kJ/mol, E'2=63.11 kJ/mol, 高于成醚的活化能, 反应体系不发生烯烃相互转化的异构化反应.     

1-丁烯氢甲酰化反应的宏观动力学研究

采用三苯基膦羰基氢化铑作为催化剂,进行1-丁烯氢甲酰化合成戊醛反应,主要考察温度、铑浓度、配体浓度、丁烯浓度、合成气中H2和CO分压等因素对反应速率的影响.动力学研究表明温度、Rh浓度、丁烯浓度和H2分压的增加均可提高反应速度,CO分压和配体量的增加使反应速度降低.给出了RhH(CO)(PPh3)3催化1-丁烯氢甲酰化的反应动力学方程,并采用非线性最小二乘法对模型进行参数估值,计算值与实验值具有较好的一致性.     

DFT法研究离子液中EMIM~ 催化丁烯双键异构反应机理(II)

用密度泛函理论(DFT)在B3LYP/6鄄31G(d,p)的计算水平上研究了离子液中1鄄乙基鄄3鄄甲基咪唑阳离子(EMIM )的4鄄H和5鄄H原子催化丁烯双键异构反应的可能途径,优化了反应体系的平衡态和过渡态的几何构型,分析了反应过程中键参数的变化,通过振动分析对平衡态和过渡态进行了验证.计算结果表明,离子液中的EMIM 首先通过4鄄H和5鄄H原子吸附丁烯,进而催化丁烯的双键异构反应,EMIM 的4鄄H和5鄄H催化1鄄丁烯异构为2鄄丁烯的正反应活化能分别为204.2和207.3kJ·mol-1,逆反应活化能约为220.9和223.8kJ·mol-1,反应为基元反应.     

丁烯异构化L-H机理复杂反应动力学

用玻璃外循环无梯度反应器研究了丁烯异构化L-H机理复杂反应动力学. 用正交设计法估计了动力学方程中的参数. 色谱法测定了丁烯吸附热, 并研究了异构化生成反-2-丁烯及顺-2-丁烯的动力学方程.     

分子筛催化cis-2-丁烯的双键异构反应机理的DFT研究

基于含有两个Si和一个Al的分子筛3T簇模型, 利用密度泛函方法(DFT)研究了分子筛催化1-丁烯双键异构为cis-2-丁烯的反应机理. 在B3LYP/6-31G(d,p)计算水平上对反应各驻点进行了全优化, 并计算了反应的活化能. 研究发现, 分子筛上的酸性OH基团首先通过物理吸附靠近1-丁烯的双键, 形成了π配位复合物后, 丁烯双键的端基C原子逐渐抽取这个质子, 同时相邻酸性位的一个O原子也抽取丁烯碳链上的一个H原子, 形成吸附态的cis-2-丁烯, 最后通过脱附形成产物, 使分子筛复原, 反应按照协同反应机理发生. 计算得到的表观活化能是55.9 kJ/mol, 与实验结果接近.     

Rh-BIPHEPHOS催化剂作用下的丁烯异构与氢甲酰化反应（英文）

为了深入研究丁烯氢甲酰化反应中可能发生的异构化与氢甲酰化反应,在Rh-BIPHEPHOS的催化作用下,对比研究了不同丁烯原料在不同温度下与合成气的反应。结果表明,1-丁烯与合成气反应时,异构化产物(2-丁烯)比氢甲酰化产物多,而以2-丁烯作为原料时,氢甲酰化反应占优势;受到1-丁烯和2-丁烯之间反应平衡的限制,温度对异构化反应有较大的正向影响。此外,在Rh-BIPHEPHOS的催化作用下,因为BIPHEPHOS较大的咬合角限制了异戊醛形成过程中的中间重排,所以产物中正戊醛的量要比异戊醛多。     

1-丁烯齐聚反应Ⅲ对-甲基苯磺酸镍及聚苯乙烯磺酸镍催化体系

本文考察了对-甲基苯磺酸镍/二氯乙基铝均相催化剂对1-丁烯齐聚反应的催化作用;考察了聚苯乙烯磺酸镍/二氯乙基铝固相化催化剂对1-丁烯齐聚反应的催化作用;通过对产物组成、原料丁烯异构体分析及所发现的反应产物中微量C_6烯烃,作者对均相催化剂和固相化催化剂进行了关联.     

双亚磷酸酯和双膦混合配体在丁烯氢甲酰化反应中的应用研究

考察了双亚磷酸酯配体Bisphosphite 1、Bisphosphite 2及双膦配体DPPE、DPPP、DPPB、BISBI在丁烯氢甲酰化反应中的反应活性和选择性,并对双亚磷酸酯配体和双膦配体进行混合,应用到丁烯氢甲酰化反应当中,对混合配体进行筛选发现Bisphosphite 1与DPPB混合配体的反应效果最佳,明显提高了1-丁烯氢甲酰化产物醛的正异构比,并通过31P NMR等方法推测了混合配体与铑配位的关键配合物中间体.通过正交实验优选了铑催化剂浓度、Bisphosphite 1浓度与DPPB浓度,其优化的催化剂配方对1-丁烯氢甲酰化的正异构比达到76.3,平均TOF 1821 h-1.     

铑配合物催化丁烯氢甲酰化性能的研究

制备了一系列铑配合物,并对其催化丁烯氢甲酰化的催化性能进行了研究.在1-丁烯的反应中,RhCl(PPh3)3和trans-RhCl(CO)(PPh3)2的反应速度很慢,而RhH(CO)(PPh3)3、Rh(CO)2(acac)和 Rh(CO)(acac)(PPh3)三者反应速度都很快.而不同丁烯原料氢甲酰化的反应速度也各不相同,反应速度依次为1-丁烯》2-丁烯》异丁烯.     

The solvent extraction of alkali metal picrates with 4,13-N,N'-dibenzyl-4,13-diaza-18-crown-6

Extraction of alkali metal picrates with N,N'-dibenzyl-18-crown-6 was carried out, with dichloromethane as water-immiscible solvent, as a function [ligand]/[metal cation]. The extractability of metal picrates (Li(+), Na(+), K(+), Rb(+), Cs(+)) was evaluated as a function of [L]/[M(+)]. The extractability of complex cation-picrate ion pairs decreases in this sequence: Li(+)>Rb(+)>Cs(+)>K(+)>Na(+). The overall extraction equilibrium constants (K(ex)) for complexes of N,N'-dibenzyl-18-crown-6 with alkali metal picrates between dichloromethane and water have been determined at 25 degrees C. The values of the extraction constants (logK(ex)) were determined to be 10.05, 6.83, 7.12, 7.83, 6.73 for Li(+), Na(+), K(+), Rb(+) and Cs(+) compounds, respectively. DB186 shows almost 2-fold extractability against Li(+) compared to the other metal picrates, whereas it shows no obvious extractability difference amongst the other metal cations when [L]/[M(+)] is 0.2-1. However, an increasing extractability is observed for Cs(+) when [L]/[M(+)] [1].     

碱金属离子对Fe(phen)3/Y催化氧化性能的影响

采用自由配体法,将铁邻菲啰啉(Fe(phen)3)配合物封装在含有不同碱金属阳离子的Y型分子筛中,制备了系列Fe(phen)3/M-Y(M=Li+,Na+,K+和Cs+)催化剂.采用X射线衍射、红外光谱、紫外-可见光谱、热重-差热分析、电感耦合等离子原子发射光谱、N2吸附-脱附以及催化氧化反应考察了碱金属离子对Fe(phen)3/M-Y催化剂物化性质和催化氧化性能的影响.结果表明,交换有不同碱金属离子的Y型沸石中Fe(phen)3的封装量不同,而且Fe(phen)3在Y型沸石中的热稳定性随着碱金属离子半径的增加有所降低,其中Fe(phen)3/Li+-Y具有最高的配合物封装量和热稳定性能.在环己烷或苯乙烯氧化反应中,在较低的反应温度下,Fe(phen)3/K+-Y表现出最高的催化活性,而在较高的反应温度下,Fe(phen)3/Cs+-Y的催化活性最高,碱金属离子对Fe(phen)3/M-Y催化氧化性能的影响是电子效应、空间限制作用和扩散效应的综合结果.     

Growth of filamentous carbon from the surface of Ni/SiO2 doped with alkali metal bromides

The growth of ordered filamentous carbon, catalytically generated from the decomposition of ethylene, has been studied over the temperature range 673-898 K using an 11% w/w Ni/SiO2 catalyst doped to varying degrees (0.1-9.3% w/w) with a range of alkali metal bromides. The effect of these alkali metal/halogen adatoms in promoting/inhibiting carbon growth has been assessed and variations in the associated carbon structural characteristics have been examined. The introduction of Li consistently promoted filamentous carbon growth (where 723 K相似文献   

Artificial ion channel formed by cucurbit[n]uril derivatives with a carbonyl group fringed portal reminiscent of the selectivity filter of K+ channels

Novel artificial ion channels (1 and 2) based on CB[n] (n = 6 and 5, respectively) synthetic receptors with carbonyl-fringed portals (diameter 3.9 and 2.4 A, respectively) can transport proton and alkali metal ions across a lipid membrane with ion selectivity. Fluorometric experiments using large unilamellar vesicles showed that 1 mediates proton transport across the membranes, which can be blocked by a neurotransmitter, acetylcholine, reminiscent of the blocking of the K+ channels by polyamines. The alkali metal ion transport activity of 1 follows the order of Li+ > Cs+ approximately Rb+ > K+ > Na+, which is opposite to the binding affinity of CB[6] toward alkali metal ions. On the other hand, the transport activity of 2 follows the order of Li+ > Na+, which is also opposite to the binding affinity of 2 toward these metal ions, but virtually no transport was observed for K+, Rb+, and Cs+. It is presumably because the carbonyl-fringed portal size of 2 (diameter 2.4 A) is smaller than the diameters of these alkali metal ions. To determine the transport mechanism, voltage-clamp experiments on planar bilayer lipid membranes were carried out. The experiments showed that a single-channel current of 1 for Cs+ transport is approximately 5 pA, which corresponds to an ion flux of approximately 3 x 107 ions/s. These results are consistent with an ion channel mechanism. Not only the structural resemblance to the selectivity filter of K+ channels but also the remarkable ion selectivity makes this model system unique.     

二氧化硅负载的不同碱金属硝酸盐催化乳酸缩合反应制备2, 3-戊二酮的催化性能比较研究

考察了二氧化硅负载的不同碱金属硝酸盐催化乳酸缩合制备2, 3-戊二酮的催化性能。在考察的碱金属硝酸盐如硝酸锂、硝酸钠、硝酸钾和硝酸铯作为催化剂的前驱体中,重点关注的是碱金属阳离子对乳酸缩合反应的影响。通过对这些硝酸盐前驱体在反应中的作用研究,发现硝酸铯的催化性能最佳。为了探究影响催化剂性能的原因,对新鲜催化剂和用过的催化剂采用X射线衍射（XRD）、傅里叶变换红外（FT-IR）光谱进行表征,发现所有的硝酸盐在反应过程中快速地转变为乳酸盐,并认为乳酸盐才是催化活性物种。随后,又借助CO₂程序升温脱附（CO₂-TPD）表征手段对用过的催化剂的碱性进行表征,发现二氧化硅负载的硝酸铯具有最强的碱性。乳酸缩合反应制备2, 3-戊二酮被广泛认为是碱催化反应,因此,二氧化硅负载的硝酸铯展示了最佳的催化性能。此外,本文还讨论了反应温度、硝酸盐的负载量等工艺条件对反应的影响。以4.4%（x,摩尔分数）CsNO₃/SiO₂为催化剂,在反应温度为300 ℃条件下,2, 3-戊二酮的收率达54.1%。     

Photometric reagents for alkali metal ions, based on crown-ether complex formation--III. 4'-picrylaminobenzo-15-crown-5 derivatives

An extraction study of alkali metal cations has been made with crown-ether reagents, 4'-picrylaminobenzo-15-crown-5 derivatives (HL). On dissociation in alkaline medium, the orange HL gives the blood-red anion L(-) and extracts alkali metal ions into chloroform as coloured complexes of composition ML.HL or ML. The ease of extraction decreases in the order, K(+) > Rb(+) > Cs(+) > Na(+) > Li(+). The extracted complexes are ML.HL for K(+) and Rb(+), and both ML.HL and ML for Na(+). The Li(+) complex is not extracted. The photometric determination of 10-800 ppm of K(+) is possible in the presence of other alkali and alkaline earth metal ions.     

Na^+/CaO催化剂上的甲烷氧化偶联

研究了不同碱金属离子对CaO的促进作用,发现以Na~+的添加效果最好。在此基础上,研究了不同含钠化合物对CaO的促进作用,并用脉冲反应技术研究Na~+/CaO催化剂表面氧物种的特性及其作用。CaO表面上存在非选择性氧化的氧物种。Na~+对CaO的修饰作用是抑制非选择性氧化。当表面上的非选择性氧化的氧物种消耗后,体相的晶格氧会向表面迁移,以补充消耗掉的表面氧物种。消耗掉的表面氧物种也可由气相氧补充。CH_4脉冲和混合气脉冲说明仅靠[Na~+O~-]中心不足以使甲烷转化成C_2产物,必须有气相氧的参与才能使甲烷转化成C_2产物。     

催化剂对CaO固硫反应动力学的影响

提高CaO的固硫率是对煤炭燃烧污染防治的研究热点。本研究探索用催化剂提高CaO固硫率的可行性及其对固硫反应动力学的影响。用热天平测试了在CaO中添加不同催化剂的固硫反应的进程,并采用等效粒子模型处理实验数据,计算了表面化学反应控制阶段及产物层扩散控制阶段的动力学参数。实验表明,CaO固硫反应初期为表面化学反应控制阶段,后期转为产物层扩散控制阶段。以碱金属的盐类为催化剂,它们均能使固硫反应前期的化学反应控制阶段的反应活化能下降,并按Li,Na,K,Cs的顺序依次递减,而碱金属盐的负离子主要影响产物层扩散阶段的固硫反应。     

Relative binding affinities of alkali metal cations to

The binding affinity and selectivity of a new ionophore, [1(8)]starand (1), toward alkali metal cations in methanol were examined through NMR titration experiments and free energy perturbation (FEP) and molecular dynamics simulations. The preference was determined to be K(+) > Rb(+) > Cs(+) > Na(+) > Li(+) in both FEP simulations and NMR experiments. The FEP simulation results were able to predict the relative binding free energies with errors less than 0.13 kcal/mol, except for the case between Li(+) and Na(+). The cation selectivity was rationalized by analyzing the radial distribution functions of the M-O and M-C distances of free metal cations in methanol and those of metal-ionophore complexes in methanol.     

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

Structural information of gas phase complexes of poly(ethylene glycol) (PEG) cationized by one or two different alkali metal ions is inferred from MS and MS/MS experiments performed with an electrospray quadrupole ion trap mass spectrometer. The rationale for selecting PEG was that its sites for cation binding are non-selective with respect to the repeating monomeric unit of the polymer, but there is selectivity with respect to the formation of an inner coordination sphere specific to each metal ion. The dissociation of [M1+ M2+ (EO23)], where EO23 = linear polymer of ethylene oxide, 23 units in length, resulted in loss of one of the alkali metal ions, with preference for loss of the larger cation, with no fragmentation of the PEG backbone for Na, K, Rb, and Cs. Li was not examined in this portion of the study. The selectivity for loss of the larger alkali metal ion was [Na+ K+ (EO23)] to [Na+ (EO23)] + K+ at 100%; [K+ Rb+ (EO23)] to [K+ (EO23)] + Rb+ at 93%; and [Rb+ Cs+ (EO23)] to [Rb+ (Eo23)] + Cs+ at 99%. The resolution of [M+ (EOx)] for x = 20-30 was dependent on the alkali metal ion, with the highest resolution observed for Cs+ and the lowest for Na+. These results are discussed with respect to the packing of the oxygen atoms on PEG (M.W.(avg) = 1000) around an alkali metal ion of different radius, and how this packing leads to an ensemble of unique structures, and therefore mobilities for [M+ (EOx)].