苯乙烯氢甲酰化反应铱基催化剂的改性研究

研究了无机盐对铱基催化剂在苯乙烯氢甲酰化反应中催化性能的改进。结果表明:铱基的羰基配合物Ir2(CO)8对反应具有较好的催化活性和较高的选择性,NaCl对催化剂的改性效果较好。最佳反应条件:甲苯作溶∶PCO=1∶1),NaCl∶Ir2(CO)8=1∶1(摩尔比),苯基丙醛的产率剂,Ir2(CO)8作催化剂,温度100℃,压力5.0MPa(PH2达到64.5%,i/n=2.48。     

季铵盐离子液体催化苯胺选择性烷基化反应

对离子液体介质中苯胺与卤代烃的N-单烷基化反应,考察了9种不同结构的季铵盐、季鏻盐对反应的影响。结果表明,在60℃,用四丁基氯化铵作催化剂、三乙胺作缚酸剂,n(三乙胺)∶n(苯胺)∶n(卤代烃)∶n(四丁基氯化铵)=2∶1∶1∶0.05,苯胺能快速有效地与卤代烃发生N-烷基化反应,高选择性制备仲胺化合物,苯胺转化率达到86%,仲胺选择性达到87%,通过简单的乙醚萃取就可实现产物分离。季铵盐离子液体对邻位或对位有取代基的苯胺烷基化反应,也具有高的苯胺转化率和仲胺选择性,可以代替咪唑鎓盐离子液体用于苯胺选择性单烷基化反应。     

盐酸丁卡因的合成工艺改进

以对氨基苯甲酸乙酯(苯佐卡因,EPABA)为原料,经过N-烷基化、水解、酯化三步反应得到盐酸丁卡因。采用FTIR、~1HNMR和HPLC对产物进行了表征。对N-烷基化过程、水解条件、酯化条件进行了优化。结果表明:盐酸丁卡因被成功合成。N-烷基化的最佳工艺条件为:反应温度60℃,n(三乙胺)∶n(EPABA)∶n(1-溴丁烷)=1.2∶1.0∶4.6,在此条件下合成对丁氨基苯甲酸乙酯(Ⅰ),产品收率为75.62%;与现有工艺路线相比,在生成关键中间体Ⅰ时成功减少了双丁基化副产物的产生;水解反应的最佳合成条件为:n(Na OH)∶n(Ⅰ)=1.4∶1.0、反应温度为50℃、反应时间为8 h,在此条件下合成对丁氨基苯甲酸(Ⅱ)的收率为99.78%;当n[(β-氯乙基)二甲胺盐酸盐,Ⅲ]∶n(Ⅱ)=1.3∶1.0、反应温度为116℃、溶剂为甲基异丁基酮时,合成了盐酸丁卡因,收率为85.07%。     

N-甲基乙酰胺合成工艺研究

以乙酸甲酯、一甲胺为原料合成N-甲基乙酰胺,在n(乙酸甲酯)∶n(一甲胺)=1∶1.10~1.15,助剂用量为原料乙酸甲酯的20%~30%(质量分数),反应温度120~125℃,反应时间3.5~4.0h;反应压力2.0~2.5MPa,催化剂加入量占乙酸甲酯原料量0.05%~0.07%的条件下,乙酸甲酯转化率≥95%,N-甲基乙酰胺选择性≥93%。     

绿色溶剂法制备2,6-二苦氨基吡啶的研究

采用水作为溶剂,以2,6-二氨基吡啶(DAP)和2,4,6-三硝基氯苯为原料,经N-烷基化反应,制得2,6-二苦氨基吡啶(PAP)。考察了相转移催化剂、反应物配比、缚酸剂用量、反应温度、反应时间等对PAP收率的影响。结果表明,优化工艺条件为:采用AEO9作相转移催化剂,n(三硝基氯苯)∶n(二氨基吡啶)=2.2∶1,n(碳酸氢钠)∶n(二氨基吡啶)=1.83∶1,反应温度95℃,反应时间为5 h。此时2,6-二苦氨基吡啶的得率可达84.6%,熔点315℃,液相色谱分析纯度为97.6%。     

绿色溶剂法制备2,6-二苦氨基吡啶的研究

采用水作为溶剂,以2,6-二氨基吡啶(DAP)和2,4,6-三硝基氯苯为原料,经N-烷基化反应,制得2,6-二苦氨基吡啶(PAP)。考察了相转移催化剂、反应物配比、缚酸剂用量、反应温度、反应时间等对PAP收率的影响。结果表明,优化工艺条件为:采用AEO9作相转移催化剂,n(三硝基氯苯)∶n(二氨基吡啶)=2.2∶1,n(碳酸氢钠)∶n(二氨基吡啶)=1.83∶1,反应温度95℃,反应时间为5 h。此时2,6-二苦氨基吡啶的得率可达84.6%,熔点315℃,液相色谱分析纯度为97.6%。     

N,N-二甲基-3-氯丙胺盐酸盐的相转移催化合成

以1,3-溴氯丙烷和33%二甲胺水溶液为原料,PEG-600为相转移催化剂进行烷基化反应得到了N,N-二甲基-3-氯丙胺盐酸盐,考察了相转移催化剂用量、二甲胺水溶液与1,3-溴氯丙烷摩尔比、反应温度和反应时间等因素对产率的影响。确定适宜反应条件为:n(二甲胺水溶液)∶n(1,3-溴氯丙烷)=1.2,PEG-600 2.0 g,反应时间4 h,反应温度为35~40℃,产率可达73.7%。     

微波促进高相对分子质量N-丁烷基壳聚糖的合成

在微波促进下首先对高相对分子质量壳聚糖碱化,再使之与溴代正丁烷进行烷基化反应,合成出了高取代度的N-丁烷基化壳聚糖.在n(氢氧化钠)∶n(壳聚糖)=4∶1,(壳聚糖粘均相对分子质量为1.49×106)、60℃下微波碱化处理1h、n(溴代正丁烷)∶n(碱化壳聚糖)=1.4∶1、80℃烷基化反应4h的较佳反应条件下,所得产...     

大颗粒SiO_2载体负载Ir/FeO_x催化剂的巴豆醛加氢性能

选择粒径(1~3)mm的Si O2为载体,采用浸渍法制备Ir/Fe Ox/Si O2催化剂,考察Fe含量对催化剂气相巴豆醛选择加氢反应性能的影响,采用X射线粉末衍射、拉曼光谱及光电子能谱等对催化剂进行表征。结果表明,随着Fe添加量的增加,反应1 h时巴豆醛转化率和反应10 h时巴豆醇选择性呈现先提高后下降趋势,n(Fe)∶n(Ir)=1.0时,反应1 h时巴豆醛转化率最高(达67%);n(Fe)∶n(Ir)=0.3时,反应1 h时巴豆醛转化率和反应10 h时巴豆醇选择性分别达88%和95%,反应过程中催化剂表面积炭是导致巴豆醛转化率降低的主要原因。对于同种催化剂,反应后电子结合能往低结合能方向偏移可能是导致选择性提高的原因。     

苯乙基间苯二酚的合成工艺研究

以间苯二酚和苯乙烯为原料、乙醚为溶剂、N-甲基吡咯烷酮硫酸氢盐为催化剂合成苯乙基间苯二酚,并考察了催化剂、溶剂、物料比、反应温度、反应时间等因素对合成反应的影响。结果表明,在n(间苯二酚)∶n(苯乙烯)∶n(N-甲基吡咯烷酮硫酸氢盐)∶n(乙醚)为1∶1∶0.2∶3、反应温度为40℃、反应时间为5h的最优条件下,苯乙基间苯二酚产率达到最高,为88%。     

铑-铱双金属催化甲醇制醋酸工艺

采用贵金属铑和铱作为催化剂主成分,以α形态的三氧化二铝为载体,组成双金属非均相催化剂,考察该催化剂的最佳制备条件及催化效果.选用硝酸铑和硝酸铱分别作为铑和铱的前躯体,采用先浸渍焙烧铑再浸渍焙烧铱的制备方法,分别制备了不同铑铱质量分数的双金属催化剂,催化剂中的金属质量分数通过ICP-AES法来测定.该双金属催化剂在450...     

Catalytic combustion of methane over barium hexaferrites

Barium hexaferrite BaFe₁₂O₁₉ and iridium-containing barium hexaferrites have been prepared by the citrates gel method. Their catalytic activity in methane combustion has been evaluated. BaFe₁₂O₁₉ is an efficient catalyst for this reaction, and the introduction of iridium in the hexaferrite structure does not improve this activity. Mössbauer spectroscopy suggests that a part of the iridium ions are incorporated in the hexaferrite structure, however in crystallographic sites where they cannot interact with the gas phase. Infrared study of CO adsorption reveals the presence of two types of iridium particles in the surface: small Ir particles, in strong interaction with the hexaferrite structure, and some larger Ir particles which were not incorporated into the lattice.     

Graphene–NHC–iridium hybrid catalysts built through –OH covalent linkage

Graphene oxide (GO) and thermally reduced graphene oxide (TRGO) were covalently modified with imidazolium salts through their hydroxyl surface groups. The selective reaction of the –OH groups with p-nitrophenylchloroformate produced labile intermediate organic carbonate functions which were used for the covalent anchoring of a hydroxy-functionalized imidazolium salt. Nanohybrid materials containing iridium N-heterocyclic carbene (NHC)-type organometallic complexes were prepared by causing the imidazolium-functionalized materials to react with [Ir(μ-OMe)(cod)]₂. The iridium content of the graphene-based hybrid catalysts, as determined by XPS and ICP-MS was the order of ∼5 and 10 wt.%, for the TRGO and GO-based materials, respectively. The graphene-supported iridium hybrid materials were active in the heterogeneous hydrogen-transfer reduction of cyclohexanone to cyclohexanol with 2-propanol/KOH as the hydrogen source. The thermally reduced graphene–NHC–iridium hybrid catalyst showed the best catalytic performance with an initial TOF of 11.500 h⁻¹, slightly better than the related acetoxy-functionalized NHC iridium homogeneous catalyst. A good catalyst recyclability and stability were achieved.     

A site-isolated mononuclear iridium complex catalyst supported on MgO: Characterization by spectroscopy and aberration-corrected scanning transmission electron microscopy

Supported mononuclear iridium complexes with ethene ligands were prepared by the reaction of Ir(C₂H₄)₂(acac) (acac is CH₃COCHCOCH₃) with highly dehydroxylated MgO. Characterization of the supported species by extended X-ray absorption fine structure (EXAFS) and infrared (IR) spectroscopies showed that the resultant supported organometallic species were Ir(C₂H₄)₂, formed by the dissociation of the acac ligand from Ir(C₂H₄)₂(acac) and bonding of the Ir(C₂H₄)₂ species to the MgO surface. Direct evidence of the site-isolation of these mononuclear complexes was obtained by aberration-corrected scanning transmission electron microscopy (STEM); the images demonstrate the presence of the iridium complexes in the absence of any clusters. When the iridium complexes were probed with CO, the resulting IR spectra demonstrated the formation of Ir(CO)₂ complexes on the MgO surface. The breadth of the ν_CO bands demonstrates a substantial variation in the metal–support bonding, consistent with the heterogeneity of the MgO surface; the STEM images are not sufficient to characterize this heterogeneity. The supported iridium complexes catalyzed ethene hydrogenation at room temperature and atmospheric pressure in a flow reactor, and EXAFS spectra indicated that the mononuclear iridium species remained intact. STEM images of the used catalyst confirmed that almost all of the iridium complexes remained intact, but this method was sensitive enough to detect a small degree of aggregation of the iridium on the support.     

Ir/C催化剂氯代硝基苯选择性催化加氢反应性能

采用浸渍法制备Ir/C和Pd/C催化剂,并用于氯代硝基苯选择性催化加氢反应,采用ICP-MS、XRD、XPS和TEM等手段对催化剂进行表征。结果表明,在相同负载量条件下,Ir在活性炭表面的分散与Pd有显著差异,Ir颗粒粒径更小且更均匀。在氯代硝基苯液相催化加氢反应中,Ir催化剂的催化活性较低,对氢解脱氯副反应有较好的抑制作用,这些性能与Ir的特殊性能有关。     

Dehydrogenation of methylcyclohexane over Pt supported on Mg–Al mixed oxides catalyst: The effect of promoter Ir

To enhance the hydrogen release during hydrogen storage, several Pt–Ir supported on Mg–Al mixed oxide catalysts were prepared and then applied into the dehydrogenation of methylcyclohexane (MCH) in this study. The effects of iridium content, reduction temperature on the activity and stability of the catalysts were studied in detail. In the presence of Ir, metal particle size was decreased and electron transfer between Ir and Pt was observed. High reduction temperature increased the metallic Ir content but enlarged the particle size of active sites. During the dehydrogenation reaction on Pt–Ir bimetallic catalyst, MCH was efficiently converted into toluene and PtIr-5/Mg–Al-275 exhibited the highest activity. After prolonging the residence time and raising the reaction temperature to 350 °C, the conversion and hydrogen evolution rate were increased to 99.9% and 578.7 mmol·(g Pt)⁻¹·min⁻¹, respectively. Moreover, no carbon deposition was observed in the spent catalyst, presenting a high anti-coking ability and good potential for industrial application.     

Selective Hydrogenation of 5‐Ethoxymethylfurfural over Alumina‐Supported Heterogeneous Catalysts

We report here the synthesis and testing of a set of 48 alumina‐supported catalysts for hydrogenation of 5‐ethoxymethylfurfural. This catalytic reaction is very important in the context of converting biomass to biofuels. The catalysts are composed of one main metal (gold, copper, iridium, nickel, palladium, platinum, rhodium, ruthenium) and one promoter metal (bismuth, chromium, iron, sodium, tin, tungsten). Using a 16‐parallel trickle‐flow reactor, we tested all 48 catalyst combinations under a variety of conditions. The results show that both substrate conversion and product selectivity are sensitive towards temperature changes and solvent effects. The best results of >99% yield to the desired product, 5‐ethoxymethylfurfuryl alcohol, are obtained using an iridium/chromium (Ir/Cr) catalyst. The mechanistic implications of different possible reaction pathways in this complex hydrogenation system are discussed.     

铱催化ω-苄基苯乙酮类化合物的合成研究

以碳双三苯基膦氯化铱(Ir(Pph_3)(CO)Cl)为催化剂,3,3-二苯丙基-2-丙烯-醇类化合物(1a~1g)为原料合成ω-苄基苯乙酮类化合物(2a~g),其结构经过核磁共振氢谱、碳谱和元素分析表征确认。以3,3-二苯丙基-2-丙烯-醇(1a)为模板,研究了催化剂、物料比γ[n(3,3-二苯丙基-2-丙烯-醇):n(Ir(Pph_3)(CO)Cl)]、溶剂以及温度对2a产率的影响。确定了最终的反应条件为:温度为100℃,催化剂为3 mmol%的Ir(pph_3)(CO)Cl,溶剂为甲苯,碱性添加剂为K_2CO_3,并通过最优条件合成了7种羰基化合物2a~2g,产率介于85%~98%之间,此方法具有操作简单、原子经济性好、产率高、底物普适性良好等诸多优点。     

A Cooperative Catalytic System of Platinum/Iridium Alloyed Nanoclusters and a Dimeric Catechol Derivative: An Efficient Synthesis of Quinazolines Through a Sequential Aerobic Oxidative Process

A cooperative catalytic system of heterogeneous polymer‐supported bi‐metallic platinum/iridium (Pt/Ir) alloyed nanoclusters and 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spiro‐bisindane (TTSBI) enabled the facile preparation of quinazoline derivatives with low catalyst loadings and broad substrate scope under mild aerobic oxidative conditions. The ability to perform the reaction in gram‐scale and under open‐air conditions highlights the synthetic application of this cooperative catalytic system.