Co-B/SBA-15非晶态催化剂应用于肉桂醛选择性加氢的研究

以介孔材料SBA-15作为载体,采用浸渍法制备Co-B/SBA-15非晶态催化剂,该样品仍然保持SBA-15特有的有序规整孔道结构,Co-B非晶态合金颗粒均匀分布在孔道内壁,采用普通SiO2载体制备的Co-B/ SiO2,Co-B颗粒主要分布在外表面.在肉桂醛选择性加氢制肉桂醇中,Co-B/SBA-15的催化活性和对肉桂醇的最佳得率显著高于Co-B/SiO2,主要归因于活性位的高分散,规整的孔道结构,以及独特的活性位团簇结构和电子态.     

锌对非晶态Co-B合金的改性及催化肉桂醛加氢为肉桂醇的研究

采用KBH4还原法制备了非晶态Co-B和Co-Zn-B催化剂,以肉桂醛选择加氢制肉桂醇为探针反应,研究了Zn对Co-B非晶态催化剂的修饰改性作用,并采用XRD、DSC、XPS、和H2-TPD对催化剂进行了表征.研究表明,少量的Zn没有改变Co-B催化剂的非晶结构,但提高了催化剂主体的热稳定性,其中1%的Zn可使Co-B非晶态催化剂主体结晶放热峰提高12K,并在665K出现新的H2脱附峰,说明催化剂因掺入锌形成了新的氢吸附中心,锌在催化剂中以金属态和氧化态两种形式存在.催化剂的整体均衡而局部电子分布不均衡的缺陷势结构增强了对肉桂醛分子C=O双键O原子的侧链偶合吸附与金属氧化物的金属离子对羰基的极化作用协同活化了肉桂醛的C=O双键,提高了催化剂对C=O双键的加氢选择性.加氢反应工艺条件及催化剂寿命研究表明,适宜的反应温度为413K,氢压为2.5MPa,反应时间为3.0h,肉桂醇的最高产率可达84.0%,并具有较好的催化稳定性.     

Co-B非晶态合金催化肉桂醛液相选择性加氢制备肉桂醇的研究

本文首次报道Co-B非晶态合金催化剂应用于肉桂醛（CMA）液相选择性加氢制备肉桂醇（CMO），考察了催化活性、CMO选择性及其得率以及不同湿度预处理的影响。实验发现，Co-B非晶态合金催化剂的催化活性和对CMO的选择性显著优于Raney Co等催化剂，加热晶化后导致其催化活性显著下降而对CMO的选择性略有升高，根据XRD，SEM，XPS，BET等一系列的表征，初步讲座了Co-B催化剂催化性能与催化剂结构的关系。     

1,10-菲啰啉修饰Cu/Al2O3催化肉桂醛羰基高效选择性加氢

肉桂醛作为α,β-不饱和醛的代表性物质,其羰基选择性加氢的高效催化剂设计还存在一定挑战.经过1,10-菲啰啉(L₁)修饰制备的Cu催化剂(Cu/Al₂O₃-L₁),可以在肉桂醛几乎完全转化的情况下实现>95%的肉桂醇选择性.表征和DFT结果表明,1,10-菲啰啉的空间位阻限制了肉桂醛的平面吸附,提高了肉桂醇的选择性,同时其与Cu的相互作用降低了H₂的解离能,提高了催化剂的活性.这项工作强调了含N-配体在催化剂表面修饰中的重要性,并为进一步合理设计高选择性加氢催化剂提供了一些借鉴.     

Sn对肉桂醛加氢催化剂Pt/Al2O3的修饰作用

研究了负载型Pt催化剂上肉桂醛加氢反应规律,并对Sn的修饰作用进行了考察.未修饰催化剂Pt/Al2O3上,主要以C=C加氢为主;加入少量Sn修饰剂,肉桂醛加氢活性大幅度提高,而且C=O加氢选择性有所提高.当Sn/Pt摩尔比大于0.8后,虽然C=O加氢选择性仍较高,但加氢活性明显降低.Sn/Pt摩尔比为1的催化剂上,肉桂醛转化率高于96%时,肉桂醇选择性可高达80%.结合XRD与化学吸附等表征结果,表明电子因素和立体因素的综合作用是影响肉桂醛加氢选择性的主要因素.     

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%.     

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.     

离子液体中离子型共聚高分子保护的铂纳米粒子催化剂催化肉桂醛选择性加氢

用离子型共聚高分子poly(NVP-co-VBIM Cl-)保护离子液体[bmim]BF4中的铂纳米粒子.以肉桂醛选择性加氢制肉桂醇反应来评价铂纳米粒子的催化活性.结果表明,该体系下得到的铂纳米粒子粒径分布均一,并具有很高的稳定性.在离子液体中,此种高分子保护的铂纳米粒子对肉桂醛加氢制肉桂醇表现出良好的活性(转化率>90%)和选择性(>95%).催化剂可多次循环,其活性和选择性均能良好保持.     

固体聚合物电解质在肉桂醇电化学氧化中的应用(I)

研究使用白金-SPE 复合电极, 以二价锰离子为催化剂进行肉桂醇的电化学氧化实验. 电解结果的分析表明, 在电化学氧化中肉桂醇中的双键不被破坏. 该反应为后续化学反应(即EC 反应), 对电解生成物的选择性较高, 肉桂醛生成的电流效率高于80%, 肉桂酸生成的电流效率仪在5%左右.     

超声波辅助Ru-B非晶态合金常压催化肉桂醛加氢制备肉桂醇

采用KBH₄化学还原法制备了超细Ru-B非晶态合金催化剂。Ru-B催化剂在肉桂醇液相常压加氢中显示出较高的肉桂醇选择性。在加氢过程中使用超声辐射能大大提高反应速率而肉桂醇的选择性几乎保持不变。加氢速率随着超声频率或超声时间的增加而增加。通过XRD、XPS、TEM、BET和ICP等各种表征手段，简要研究了超声辐射对Ru-B催化剂结构和电子特征的影响。同时，还讨论了超声对肉桂醛选择性加氢制肉桂醇催化性能的促进作用。     

Co-B/γ-Al2O3非晶态催化剂的制备及其催化乳酸乙酯液相加氢性能

采用浸渍-还原法制备了负载型Co-B/γ-Al₂O₃非晶态合金催化剂, 并将其应用于乳酸乙酯液相加氢制备1,2-丙二醇(1,2-PDO)反应中, 研究了其催化加氢性能. 采用电感耦合等离子体(ICP)发射光谱仪、X射线衍射(XRD)仪、透射电子显微镜(TEM)、差示扫描量热(DSC)、X射线光电子能谱(XPS)等手段对催化剂的性能进行了表征, 考察了制备条件对催化剂性能的影响. 结果表明, 新鲜的Co-B/γ-Al₂O₃催化剂具有非晶态结构, Co-B均匀地分散在载体γ-Al₂O₃上. 随着Co负载量的增加, 催化剂的热稳定性提高, 催化剂表面Co/B原子比增加. 当金属Co理论负载量为30%(质量分数, w)时, Co-B/γ-Al₂O₃催化剂表现出最高的加氢催化性能, 在160 ℃, 氢气压力为6.0 MPa条件下反应9 h, 乳酸乙酯的转化频率(TOF)为1.41 h^-1, 转化率达到93.63%, 1,2-丙二醇的选择性达到96.10%. 催化剂的加氢性能取决于其分散均匀的Co-B纳米粒子、较高的表面Co/B原子比及Co和B之间的电子转移效应.     

Hydroformylation of 1-Octene over Nanotubular TiO2-supported Amorphous Co-B Catalysts

TiO₂ nanotubes supported amorphous Co-B(Co-B/TNTs) catalyst was prepared via impregnationchemical reduction procedure. The catalyst was characterized with transmission electron microscopy(TEM), ammonia temperature-programmed desorption(NH₃-TPD), thermogravimetry-differential thermal analysis(TG-DTA), Fourier transform infrared spectroscopy(FTIR) and Raman spectroscopy. The effects of temperature and ratio of CO to H₂ on the hydroformylation of 1-octene were studied. At an optimized reaction temperature(150℃) and volume ratio of CO to H₂(2:1), the conversion of 1-octene can reach 97.4% with a selectivity of 23.1% for total aldehydes and n/i-aldehyde molar ratio of 40:60. To obtain higher selectivity for linear aldehydes, Co-B/TNTs modified with triphenylphosphine for the hydroformylation of 1-octene were investigated. When molar ratio of P/Co was 4, the yield of total aldehydes was the highest(31.6%) with a good selectivity for linear product(n/i-aldehyde molar ratio was 70:30). In recycle use, the Co-B/TNTs catalyst modified with triphenylphosphine could be reused five times without reducing the activity and selectivity obviously. For a comparative study, all the Co-B/TNTs to catalyze the hydroformylation of other olefins exhibited high conversion under the optimized conditions.     

Co－B非晶态合金超细微粒催化剂的研究

Ｃｏ－Ｂ非晶态合金超细微粒催化剂的研究姚凯文，范以宁，陈懿，李新生（南京大学化学系，南京２１００９３；中国科学院大连化学物理研究所催化基础国家重点实验室，大连１１６０２３）关键词非晶态，超细微粒，钴基合金，硼合金，一氧化碳，加氢非晶态合金超细微粒兼有...     

超声辅助化学还原法制备高活性Co-B非晶态合金催化剂

采用超声辅助KBH4化学还原Co(OH)2胶体法制备了粒径均匀的Co-B非晶态合金.在乙腈液相选择性加氢制取乙胺反应中,与传统化学还原法制备的Co-B非晶态合金催化剂相比,该催化剂具有很高的催化活性.这归因于其Co活性位的高度分散、Co活性位对氢的强吸附,以及Co-B非晶态合金间强电子相互作用.     

Hydrogenation of Furfural to Furfuryl Alcohol over Co-B Amorphous Catalysts Prepared by Chemical Reduction in Variable Media

Five Co-B amorphous alloy catalysts were prepared by chemical reduction in different media, including pure water and pure ethanol as well as the mixture of ethanol and water with variable ethanol content, Their catalytic properties were evaluated using liquid phase furfural hydrogenation to furfuryl alcohol as the probe reaction. It was found that the reaction media had no significant influence on either the amorphous structure of the Co-B catalyst or the electronic interaction between metallic Co and alloying B. This could successfully account for the fact that all the as-prepared Co-B catalysts exhibited almost the same selectivity to furfuryl alcohol and the same activity per surface area （ Rs ）, which could be considered as the intrinsic activity, since the nature of active sites remained unchanged. However, the activity per gram of Co （ R^mH ） of the as-prepared Co-B catalysts increased rapidly when the ethanol content in the water-ethanol mixture used as the reaction medium for catalyst preparation increased. This could be attributed to the rapid increase in the surface area possibly owing to the presence of more oxidized boron species which could serve as a support for dispersing the Co-B amorphous alloy particles.     

羟基硅酸镁纳米管负载非晶态Co-B催化环己烯氢甲酰化

采用浸渍化学还原法制备羟基硅酸镁纳米管(MgSNTs)负载非晶态钴硼催化剂(Co-B/MgSNTs)。应用X衍射技术(XRD),透射电子显微镜(TEM),X射线光电子能谱仪(XPS),元素分析(ICP)和比表面积(BET)分析等手段对催化剂进行了表征。研究了催化剂对于环己烯氢甲酰化反应的催化活性及循环使用。研究结果表明,具有高比表面积(250 m2·g-1)、较强耐受性和稳定性的MgSNTs可以有效的分散金属粒子,防止活性中心团聚和流失,催化环己烯的转化率为75.8%,醛的选择性为65.8%,实验重复3次以上,催化剂依然保持良好的催化活性和选择性。     

Synthesis of a Novel Co-B/CTAB Catalyst via Solid-state-reaction at Room Temperature for Hydrolysis of Ammonia-borane

Cobalt-boride(Co-B) is emerging as one of the promising materials in the base-hydrolytic dehydrogenation of ammonia-borane(AB). In order to avoid the low specific area and poor catalytic capacity of Co-B catalyst caused by aggregation arising from the strong reducing property and rapid reaction condensation of sodium borohydride(NaBH₄), novel cobalt boride/cetyltrimethylammonium bromide(Co-B/CTAB) catalyst was obtained via solid-state grinding at room temperature, and the catalyst was further characterized by XRD, SEM, XPS and BET. The hydrogen generation rate(HGR) was then determined by the hydrolysis reaction of AB. The SEM images indicate that a lot of irregular folds and curled edges are formed on the sample with a maximum surface area of 145.57 m²/g, thus possibly resulting in the high hydrogen production(HGR was 10.68 L·min^-1·g^-1), which may be attributed to CTAB that provide favorable large specific surface area and abundant porous structure. Additionally, catalyst will not be affected by solvants during solid-state reaction. As a diluent, the surfactant CTAB hindered the reaction rate of sodium borohydride reduction to cobalt boride and obtained the novel catalyst with a large specific surface area.