Ru/ZrO2·xH2O催化剂催化肉桂醛选择性加氢制肉桂醇

采用共沉淀法制备了7.5%Ru/ZrO2·xH2O催化剂,运用N2物理吸附-脱附法、X射线衍射、X射线光电子能谱和高分辨透射电子显微镜等技术对催化剂进行了表征,并用于催化肉桂醛选择加氢制肉桂醇反应中,考察了温度、H2压力和溶剂对肉桂醛转化率和肉桂醇选择性的影响.结果表明,肉桂醛转化率随着温度或H2压力的升高而升高,而肉桂醇选择性则随之下降.该催化剂在极性溶剂中比在非极性溶剂中表现出更高的活性和肉桂醇选择性.尤其在极性溶剂三乙胺(Et3N)中反应活性最高,且具有较高的肉桂醇选择性.在Et3N中加入水可进一步提高反应活性和选择性.以V(Et3N)/V(H2O)=4的混合物为溶剂,在4MPa和70℃的优化条件下,反应6h,肉桂醛转化率为97.9%,肉桂醇选择性达85.2%.     

杂多酸盐修饰骨架镍催化剂上肉桂醛的选择加氢

研究了杂多酸盐改性：Raney Ni催化剂上肉桂醛选择加氢制备肉桂醇的反应，考察了杂多酸盐负载量、反荷阳离子、杂多阴离子对RaneyNi催化剂上肉桂醛加氢活性和选择性的影响，结果表明：随着Cu1.5PMo12O40负载量增加，肉桂醛加氢沽性降低而生成肉桂醇的选择性增加，当Cu1.5PMo12O40负载量达到6．3％时，肉桂醇的选择性达到了26．4％，而没有改性的RaneyNi催化剂上肉桂醛加氢生成肉桂醇的选择性为零；在各种不同反荷阳离子的PM012盐中，只有反荷阳离子为Cu2 的Cu1.5PMo12O40改性Raney Ni催化剂具有最高的选择性，在选定的四种杂多阴离子的铜盐中，Cu2SiMo12O40和Cu2SiW12O40改性Raney Ni催化剂的选择性为零，Cul．5PW12O40改性Raney Ni催化剂上肉桂醛加氢生成肉桂醇的选择性也比Cu1.5PMo12O40改性Raney Ni的低的多．     

Ru/ZrO2·xH2O催化剂催化肉桂醛选择性加氢制肉桂醇

采用共沉淀法制备了7.5%Ru/ZrO2·xH2O催化剂,运用N2物理吸附-脱附法、X射线衍射、X射线光电子能谱和高分辨透射电子显微镜等技术对催化剂进行了表征,并用于催化肉桂醛选择加氢制肉桂醇反应中,考察了温度、H2压力和溶剂对肉桂醛转化率和肉桂醇选择性的影响.结果表明,肉桂醛转化率随着温度或H2压力的升高而升高,而肉...     

Sn改性的Ru/H-CMK-3催化剂的制备及其肉桂醛选择性加氢性能的研究

用浸渍-原位还原法制备了Ru-Sn/H-CMK-3催化剂. 以肉桂醛选择性加氢制备肉桂醇为探针反应. 详细研究了催化剂的制备及反应条件对肉桂醛选择性加氢性能的影响. 采用X 射线粉末衍射(XRD)、比表面积(BET)、X光电子能谱(XPS)、透射电镜(TEM)等手段对催化剂结构和性质进行了表征. 结果表明, 介孔CMK-3碳材料能够更好地分散活性物种. 添加适量的Sn(IV)有利于Ru处于电子富集状态. 催化剂的主要活性物种是纳米Ru粒子, Ru和Sn之间的相互作用更加有利于C＝O的活化. 同时, 反应温度和反应压力等条件的变化对肉桂醛选择性加氢制备肉桂醇反应也具有较大的影响.     

乙醇/水溶剂体系中Pt-Co/ZrO2催化剂上肉桂醛的选择性加氢性能

研究了乙醇/水溶剂体系中Pt-Co/ZrO2催化剂上肉桂醛的选择性加氢性能研究结果表明,在乙醇/水溶剂体系中,催化剂Pt-0.4% Co/ZrO2具有良好的肉桂醛加氢活性和生成肉桂醇的选择性.载体ZrO2的织构性质对Pt-Co/ZrO2催化剂的活性具有重要影响,具有较大孔径、高比表面积的载体有利于活性组分的分散和反应底...     

Pt/MIL-101(Cr)在肉桂醛选择性加氢反应中的催化性能

采用简单易行的浸渍法将Pt纳米粒子负载到MIL-101(Cr)上, 制备了Pt/MIL-101(Cr)催化剂, 并对其在肉桂醛选择性加氢反应的催化性能进行了研究。XRD、N₂吸附、TEM和催化性能的研究结果表明, Pt的负载量对负载于MIL-101(Cr)上Pt纳米粒子的尺寸及所制备催化剂对肉桂醇的选择性有很大影响。低Pt负载量(1.0wt%)的Pt/MIL-101(Cr)较其他MOFs和无机材料在肉桂醛选择性加氢反应中表现出了高的催化性能, 在优化的反应条件下肉桂醛转化率和对肉桂醇的选择性可分别达96.5%和86.2%。Pt/MIL-101(Cr)催化剂具有良好的稳定性。Pt/MIL-101(Cr)所表现出的优良的催化性能同MIL-101(Cr)载体的孔道结构及其表面性质密切相关。     

Pt/MIL-101(Cr)在肉桂醛选择性加氢反应中的催化性能

采用简单易行的浸渍法将Pt纳米粒子负载到MIL-101(Cr)上,制备了Pt/MIL-101(Cr)催化剂,并对其在肉桂醛选择性加氢反应的催化性能进行了研究。XRD、N₂吸附、TEM和催化性能的研究结果表明,Pt的负载量对负载于MIL-101(Cr)上Pt纳米粒子的尺寸及所制备催化剂对肉桂醇的选择性有很大影响。低Pt负载量(1.0%)的Pt/MIL-101(Cr)较其他MOFs和无机材料在肉桂醛选择性加氢反应中表现出了高的催化性能,在优化的反应条件下肉桂醛转化率和对肉桂醇的选择性可分别达96.5%和86.2%。Pt/MIL-101(Cr)催化剂具有良好的稳定性。Pt/MIL-101(Cr)所表现出的优良的催化性能同MIL-101(Cr)载体的孔道结构及其表面性质密切相关。     

苯乙烯-丁二烯-苯乙烯嵌段共聚物负载Pt催化肉桂醛制备肉桂醇的研究

用紫外光交联的方法制备不同交联度的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)负载Pt的催化膜并探讨其对肉桂醛选择性加氢制备肉桂醇的催化效果.其中催化剂Pt纳米簇用微波法制备,XRD测其平均粒径为3.7 nm.膜载催化剂的负载量、光交联剂三羟甲基丙烷三丙烯酸酯(TMPTA)和光引发剂二苯甲酮(BP)的用量均为3%.用色谱-质谱联用、XRD、紫外分光光度计对膜载催化剂和反应产物进行了表征,结果表明,随着交联度的增加,肉桂醇的催化选择性先增后减,紫外光光照80s时,负载膜交联度23.63%,肉桂醛转化率为91.46,肉桂醇选择性80.98%.质谱分析表明交联度大于30%后,催化产物中开始有膜分解产生的小分子杂质出现,并随交联度的进一步增大而增多;显微镜检测同时说明此时膜结构发生变化,造成肉桂醇选择性的降低.     

特种氧化铝负载氧化钛作为异丙醇还原肉桂醛的高性能催化剂

肉桂醇在香料、香精以及医药等诸多高端领域有着重要应用,常通过肉桂醛加氢法制备.由于热力学上肉桂醛中C=C–C=O官能团的C=C双键加氢比C=O双键更有优势,因此不管是从学术角度还是工业生产角度来看,高选择性还原C=O基团都是一项极具挑战的任务.肉桂醛加氢反应的副产物苯丙醛以及苯丙醇的生成不仅导致肉桂醇收率降低,而且大大增加分离纯化成本,因此设计并制备出有利于C=O官能团高选择性氢化的高效催化剂具有重要意义.Meer-wein-Ponndorf-Verley(MPV)反应以异丙醇为氢供体,是一种可选择加氢C=C–C=O中C=O官能团的反应.目前用于MPV还原的催化剂(均相或多相)在实际应用中通常选择性不高,使得目标产物得率低且分离成本高.本文报道了负载于一种特殊氧化铝表面的氧化钛催化剂(记为TiOx/γ-Al2O3-nt),其催化肉桂醛经MPV还原为肉桂醇的催化性能优异,表征结果发现该特殊氧化铝可导致表面氧化钛呈较高比例的低价钛物种高度分散状态,从而成为一种高效的肉桂醛MPV还原催化剂.TEM结果表明,这种特殊氧化铝和普通氧化铝在形貌上有很大差别,具有比较规整的一维纳米粒子形貌.综合XRD,TEM,Raman以及H/D同位素交换表征结果,可得到氧化钛高度分散在氧化铝表面的结论.原位XPS结果表明,Ti-Ox/γ-Al2O3-nt催化剂表面具有较高浓度的Ti(III)物种,而以普通氧化铝为载体的催化剂TiOx/γ-Al2O3-c在相同的还原条件下其表面Ti(Ⅲ)物种浓度较低,这种差异的来源是具有规整形貌的一维纳米氧化铝提供了更加均匀的表面位点使得表面高度分散的氧化钛容易被还原为低价态.NH3-TPD结果表明,TiOx/γ-Al2O3-nt催化剂具有高的L酸酸量.肉桂醛MPV还原反应结果显示,表面负载氧化钛的特殊氧化铝(TiOx/γ-Al2O3-nt)是一种非常高效的催化剂,具有很高的目标产物肉桂醇的选择性,几乎观察不到副产物的生成,多次套用实验结果也证实该催化剂具有良好的稳定性.该催化剂的高性能可归纳为以下两个方面的原因:一方面,L酸是MPV还原反应的活性中心,该催化剂具有高的L酸酸量,因此转化率高;另一方面,其表面较高浓度的Ti(III)物种可以使肉桂醛以垂直吸附模式(吸附终端为C=O)在催化剂表面吸附,这种吸附模式可以高选择性地还原为目标产物肉桂醇,因此同时具有很高的选择性.     

Co/γ-Al_2O_3催化剂上肉桂醛的选择加氢──反应性能的考察

研究了γ－Al2O3负载的Co／γ－Al2O3催化剂上肉桂醛的选择加氢反应．反应结果表明,以CoCl2作为前驱物的Co／γ－Al2O3催化剂的选择性要高于以Co（NO3）2作为前驱物的Co／γ－Al2O3催化剂,而活性则正好相反．当钴的负载量小于9％时,随着钴负载量的增加,催化剂的活性和选择性随之增加,当钴的负载量大于9％时,随着钴负载量的增加,Co／γ－Al2O3催化剂的活性略有增加,而生成肉桂醇的选择性变化也很小,认为9％的钴负载量是催化剂反应活性和选择性的一个阈值．在所选定的范围内,反应温度和压力对肉桂醛加氢的选择性几乎没有影响．     

肉桂醛催化选择加氢反应中双金属的协同效应

对既含有ＣＣ键又含有ＣＯ键的分子,ＣＣ键的选择加氢意义重大［１］．α,β不饱和醛选择加氢成饱和醛就属于此类．钯是已知的可在温和条件下将α,β不饱和醛选择加氢生成饱和醛最有效的催化剂之一．人们曾研究了不同钯化合物催化剂对α,β不饱和醛中ＣＣ的双键选择加...     

Hydrogenation of crotonaldehyde and cinnamaldehyde catalyzed by water-soluble palladium complex

The selective hydrogenations of crotonaldehyde and cinnamaldehyde in the aqueous-benzene biphasic system were investigated using water-soluble palladium complex PdCl₂(TPPTS)₂ as catalyst. The hydrogenation rate of crotonaldehyde was higher than that of cinnamaldehyde under similar reaction conditions. The palladium complex selectively catalyzed the hydrogenation of CC bond in crotonaldehyde to form butanal (100%). On the contrary, hydrogenation of both CC and CO bonds in cinnamaldehyde occurred simultaneously, with the amount of phenylpropanal only slightly higher than that of phenylpropanol. However, the reduction of CO bond of cinnamaldehyde could be inhibited by the addition of Na₂CO₃ solution. Therefore, high selectivity to form phenylpropanal (91%) could be obtained by using Na₂CO₃ solution at pH 12.2. Other factors affecting the hydrogenation conversion and selectivity of crotonaldehyde and cinnamaldehyde were also discussed.     

Cobalt-catalyzed photopromoted carbonylation of chloroalkanes in the presence of KI

<正>The photopromoted carbonylation of chloroalkanes with carbon monoxide catalyzed by cobalt compounds[Co(OAc)_2,CoCl_2] in the presence of KI was carried out under ambient conditions.The results revealed that the catalytic activity of Co(OAc)_2 was higher than that of CoCl_2.A basic additive NaOAc was beneficial to the reaction.Interestingly,with NaOAc as an additive, Co(OAc)_2 and CoCl_2 exhibited similar catalytic activity.Preliminary work showed that the role of iodide ion was initially to form active iodoalkanes via substituting chloride ion in chloroalkanes in situ,and then,the carbonylation of iodoalkanes proceeded under irradiation.     

Effect of Transition Metals on Selective Hydrogenation of Cinnamaldehyde over Pt／ZrO2 Catalysts

The effect of transition metals (Cr, Mn, Fe, Co and Ni) on the hydrogenation of cinnamaldehyde over Pt/ZrO2 catalysts was studied in ethanol at 343K under 2.0MPa H2 pressure. PtCo/ZrO2 and PtFe/ZrO2 catalysts exhibit high selectivity and activity of hydrogenation for C=O (93.8% at 87.3% conversion and 83.6% at 88.6% conversion, respectively), and PtNi/ZrO2 exhibits high selectivity of hydrogenation for C=C (64.3% at 70.6% conversion). In the presence of trace H2O and NaOH, over the PtNi/ZrO2 (0.4wt%Ni) catalyst the selectivity to hydrocinnamalde hydereaches 90.6% and the conversion of cinnamaldehyde is 90.5%.     

Photopromoted carbonylation of bromobenzene under ambient conditions

The photopromoted carbonylation of bromobenzene with carbon monoxide catalyzed by inexpensive commercially available cobalt salts[Co(OAc)_2,CoCl_2]was carried out under ambient conditions.The results revealed that methyl benzoate was produced in the presence of basic additives(CH_3ONa,NaOAc or(n-C_4H_9)_3N).The catalytic activity of Co(OAc)_2was higher than that of CoCl_2.Furthermore,the activity of the carbonylation was greatly improved by addition of acetophenone,e.g.both the yield and selectivity of t...     

Catalytic activity of palladium supported on single wall carbon nanotubes compared to palladium supported on activated carbon Study of the Heck and Suzuki couplings, aerobic alcohol oxidation and selective hydrogenation

Nanoparticles (2–10 nm) of palladium have been deposited on single wall carbon nanotubes (SWNT) by spontaneous reduction from Pd(OAc)₂ or from oxime carbapalladacycle. These catalysts exhibit higher catalytic activity than palladium over activated carbon (Pd/C) for the Heck reaction of styrene and iodobenzene and for the Suzuki coupling of phenylboronic and iodobenzene. This fact has been attributed as reflecting the dramatic influence of the size particle on the activity of the palladium catalyst for CC bond forming reactions as compared to other reaction types less demanding from the point of view of the particle size. Thus, in contrast to the Heck and Suzuki reactions, Pd/C is more active than palladium nanoparticles deposited on SWNT for the catalytic oxidation by molecular oxygen of cinnamyl alcohol to cinnamaldehyde and for the hydrogenation of cinnamaldehyde to 3-phenylpropionaldehyde.     

Mn（OAc）2/Schiff base as a new efficient catalyst system for the Henry reaction of nitroalkanes with aldehydes

A series of novel Schiff bases bearing triazole structure were synthesized and characterized by IR and NMR.Mn（OAc）₂/Schiff base efficiently catalyzed Henry reaction of nitroalkanes with aldehydes to produce the corresponding products of β-nitroalcohols, under mild conditions with high yields（up to 99%）.A reaction mechanism is proposed based on the experimental results.     

Highly chemoselective hydrogenation method using novel finely dispersed palladium catalyst on silk-fibroin: its preparation and activity

A palladium-fibroin complex (Pd/Fib) was prepared by soaking silk-fibroin in MeOH solution of Pd(OAc)₂ for 2 days (under Ar atmosphere)—4 days (under air). Pd(OAc)₂ was gradually absorbed by fibroin and the rapid reduction of fibroin conjugated Pd(OAc)₂ proceeded with MeOH as a reductant at room temperature to be the Pd(0) complex. Pd/Fib catalyzed chemoselective hydrogenation of acetylenes, olefins and azides in the presence of aromatic ketones and aldehydes, halides, N-Cbz protective groups and benzyl esters which are readily hydrogenated using Pd/C or Pd/C(en) as a catalyst.     

Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over An Ultrafine Co—B Amorphous Catalyst

A novel Co-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of CoCl2 with aqueous NaBH4, which exhibited excellent activity and selectivity during the hydrogenation of cinnamaldehyde to cinnamyl alcohol in liquid phase. The optimum yield of cinnamyl alcohol was 87.6%, much better than the yield of using Raney Ni, Raney Co and other Co-based catalysts.     

Cooperative Effect of Two Metals: CoPd(OAc)4‐Catalyzed CH Amination and Aziridination

The first Co/Pd‐cocatalyzed intramolecular C?H amination and aziridination reactions were developed. Sulfamate esters were converted to oxathiazinanes by using CoPd(OAc)₄ as catalyst and PhI(OAc)₂ as oxidant. The mutual presence of both Co and Pd is crucial for the catalytic activity. This combination of two metals with simple acetate ligands provides an economical alternative to the Rh‐catalyzed insertion of nitrenoids into C?H bonds.