双溶剂法制备Pd/MIL-100及其催化Suzuki偶联反应的研究

采用溶剂热法合成了MIL-100(Cr),通过双溶剂浸渍法负载Pd纳米粒子制备负载型Pd/MIL-100催化剂。以溴苯与苯硼酸偶联合成联苯为模型反应,考察了溶剂、碱助剂、温度等因素对Suzuki偶联反应性能的影响。结果表明,以V(EtOH)∶V(H₂O)=2∶1为溶剂、K₂CO₃为碱助剂,在60℃反应0.5 h,溴苯转化率达到97%,目标产物联苯选择性>99%;催化剂对于对位和间位供电子基团取代的芳基硼酸具有良好的底物适用性;Pd/MIL-100催化剂循环使用3次仍保持良好的催化活性及稳定性。XRD、XPS、ICP及TEM表征结果表明,催化剂失活的主要原因是由于Pd纳米粒子在MIL-100表面发生了迁移团聚。     

Al2O3负载Pd基催化剂的研究进展

氧化铝的化学性质稳定，并具有丰富的孔道结构，常被用为催化剂载体来分散金属活性组分，起到提高催化剂的催化活性和稳定性的作用，已被广泛地应用于化学工业中。负载型纳米Pd基催化剂具有优异的反应活性和产品选择性，己被广泛应用于催化加氢、脱氢、碳-碳耦合等反应中。综述了近年来Al₂O₃负载Pd基催化剂的研究进展。     

PtSn/MgAl2O4-sheet催化剂的制备及其PDH反应性能

近年来，因为页岩气大规模开采的成功可以为丙烷脱氢制丙烯(PDH)工艺提供大量廉价的丙烷，丙烷脱氢制丙烯已成为最有前途和最具吸引力的丙烯生产技术。目前工业上丙烷脱氢主要采用的是负载型PtSn/Al₂O₃催化剂。然而在丙烷脱氢高温反应中，PtSn纳米粒子易烧结和积炭使催化剂遭受严重的失活。为了解决上述问题，本文合成了片状的MgAl₂O₄尖晶石载体负载PtSn金属纳米粒子，制备了PtSn/MgAl₂O₄-sheet催化剂。该催化剂具有较大的孔径，有利于PDH反应中反应物的吸附和产物的脱附，提高了催化剂的活性同时降低了积炭含量。同时片状的MgAl₂O₄尖晶石载体的(111)面与PtSn纳米颗粒存在着强的相互作用，阻止了PtSn纳米颗粒在高温反应中的烧结。在丙烷脱氢反应中，丙烷的转化率达到了43.2%，丙烯的选择性达到了95.0%，失活速率仅为0.008h^-1，其性能优于商用的PtSn/Al_...     

两种负载型钯基催化剂在Heck反应中的性能比较

制备了碳负载钯催化剂(Pd/C)以及氨基改性二氧化硅负载钯(Pd/Si O2-NH2)催化剂。两种催化剂应用于以溴苯为模型反应的Heck反应中,对比了两种催化剂的反应活性以及重复使用率。研究表明,Pd/C催化剂在Heck反应中有较高的催化活性,但是其重复使用寿命低于Pd/Si O2-NH2催化剂。     

MCM-41负载钳形钯配合物的制备及其在α-芳基化反应的应用

以MCM-41为载体,NCN钳形钯配合物为活性组分,以氨基甲酸酯和三乙氧基硅烷为联结基团,制备出负载型催化剂NCN-Pd/MCM-41,采用FTIR、XRD、氮气吸附仪对其进行了表征。结果表明,合成的催化剂具有介孔结构,无机载体和有机金属配合物均保持了原有结构的完整性。将负载型催化剂应用于催化苯乙酮与溴苯的α-芳基化反应,考察了催化剂用量、反应时间和反应温度对产率的影响。结果表明,负载型催化剂NCN-Pd/MCM-41在催化酮与溴苯的α-芳基化反应中表现出优异的催化活性,最优条件为:催化剂用量1. 0%(摩尔分数),反应时间2 h,反应温度81℃,在此条件下芳基化产物产率达到了90%,催化剂重复使用4次,产率仍在84%以上。     

MCM-41负载钳形钯配合物的制备及其在α-芳基化反应的应用

以MCM-41为载体,NCN钳形钯配合物为活性组分,以氨基甲酸酯和三乙氧基硅烷为联结基团,制备出负载型催化剂NCN-Pd/MCM-41,采用FTIR、XRD、氮气吸附仪对其进行了表征。结果表明,合成的催化剂具有介孔结构,无机载体和有机金属配合物均保持了原有结构的完整性。将负载型催化剂应用于催化苯乙酮与溴苯的α-芳基化反应,考察了催化剂用量、反应时间和反应温度对产率的影响。结果表明,负载型催化剂NCN-Pd/MCM-41在催化酮与溴苯的α-芳基化反应中表现出优异的催化活性,最优条件为:催化剂用量1. 0%(摩尔分数),反应时间2 h,反应温度81℃,在此条件下芳基化产物产率达到了90%,催化剂重复使用4次,产率仍在84%以上。     

深度脱除富氢气体中CO的纳米Ni/ZrO2催化剂

针对富氢气体中甲烷化反应深度脱除CO过程中催化剂活性不足的问题,研究了一种新型的纳米Zr O₂负载的Ni基催化剂。通过尿素水解法制备不同活性金属含量的纳米Ni/ZrO₂催化剂,在体积分数为3%CO、2%CO₂、95%H₂的富氢气氛中,采用固定床反应器,研究了在不同反应温度、体积空速WHSV等对CO转化率以及最终出口气体中CO浓度的影响,同时进行了催化剂寿命评价。研究结果表明：Ni O的负载质量分数为30%的催化剂,在反应温度为200～400℃、反应空速为1 000 h^-1的条件下,可以将CO的体积分数降低至2×10^-6以下,且催化剂在连续评价100 h内,催化剂性能稳定。研究认为,由于纳米Zr O₂对CO的吸附能力增强,有利于提高催化剂上CO甲烷化反应的效率和稳定性。     

胶体负载法制备Au/C催化剂用于乳酸合成的研究

将预先制备好的十二烷基硫醇保护的纳米金胶体负载到用硝酸处理过的活性炭上,制备得到纳米Au/C催化剂,并用1,2-丙二醇直接氧化合成乳酸的反应考评催化剂。重点讨论载体的预处理方法和负载温度对金胶体负载的影响以及载体上金的含量、粒径、热处理方式等对纳米金催化剂活性的影响。结果表明:胶体负载法制备的纳米Au/C催化剂在1,2-丙二醇直接氧化合成乳酸反应的转化率达到50%以上,选择性达到80%以上。     

腐植酸负载钯催化剂对Heck反应的催化性能

研究了腐植酸负载钯催化剂对碘苯、溴苯及其芳基卤衍生物与丙烯酸的Heck芳基化反应的催化性能。在氮气保护下，测定了时间、温度、催化剂用量、碱和溶剂对反应产率的影响。结果表明，以溴苯与丙烯酸的反应为例，催化剂在130℃反应12h，三丁胺作为碱，催化剂用量为0．44mol％的钯含量，四丁基溴化铵作为溶剂的条件下具有较好的催化性能；对碘苯及溴苯的衍生物与丙烯酸的反应也有很高的催化活性。     

KF/Al_2O_3在C-N偶联反应中的应用研究

以Cu_2O纳米颗粒作为催化剂,KF/Al_2O_3作为碱,成功实现了N-芳基咪唑类化合物的合成,其结构经1H NMR确证。考察了催化剂、配体、KF的负载量、碱的煅烧温度、溶剂、反应温度、碱的种类等反应条件对偶联反应的影响。实验结果表明,在最佳反应条件:Cu_2O纳米颗粒作为催化剂,KF/Al_2O_3-30%-450℃作为碱,DMF为溶剂,于130℃反应20 h,成功地实现了溴苯与咪唑的偶联,反应的收率达到80.8%。     

Synthesis of chitosan microsphere-resin supported palladium complex and its catalytic properties for Mizoroki–Heck reaction

Chitosan microsphere-resin supported palladium complex was synthesized and characterized by SEM/EDS, FT-IR, TG/DTA and XPS. The configuration of microsphere with a diameter of 10–100 μm was exhibited through SEM images. The microsphere-resin possesses a high thermal stability as proved by the TG/DTA. Some investigations were later carried out on the catalytic properties of the complex for Mizoroki–Heck reaction. It was found that the complex could not only efficiently catalyze Mizoroki–Heck reaction of iodobenzene with acrylic acid, but it also exhibited catalytic properties for the activated bromobenzene. Surprisingly, the complex was an efficient catalyst in inorganic base and water system, especially, a moderate yield of 76% was obtained by using water as solvent.     

无机物负载型钯催化剂的研究进展

钯催化剂是重要的金属催化剂,近年来,负载型钯催化剂作为一类新型催化剂广受关注。介绍了以硅胶、MCM-41分子筛、活性炭和金属氧化物等无机物为载体的负载型钯催化剂的特征及应用,并展望了其在不对称反应中的开发应用前景。     

Reusability, Durability and Treatability of Palladium Catalyst on a Semiconductor Plate: Comparison with Commercially Available Solid-Supported Palladium Catalysts

A palladium catalyst supported on a semiconductor plate underwent the Heck reaction effectively to afford a coupling product. The catalytic plate was easily recovered from the reaction mixture with tweezers and reused several times without any special treatment. Comparison of reusability, durability, and treatability of seven kinds of commercially available solid-supported palladium catalysts and the semiconductor-supported catalyst plate was studied.     

催化合成咔唑的研究进展

综述了催化合成咔唑的研究进展。介绍了有关负载钯和雷尼镍催化剂在脱氢反应中的理论与实验研究,阐述了以1,2,3,4-四氢咔唑为原料,经催化脱氢反应得到咔唑的具体条件,脱氢的效率与催化剂的用量和种类、溶剂的种类以及反应条件等有关。以廉价原料二苯胺合成咔唑,反应由负载钯或铂催化剂催化;2-氨基联苯可经催化氧化反应或贵金属催化的偶联反应得到合成咔唑,这两条路线是制备咔唑的重要途径。     

Systematic Study of the Oxidation of Methane Using Supported Gold Palladium Nanoparticles Under Mild Aqueous Conditions

The oxidation of methane using hydrogen peroxide has been studied using supported gold palladium catalysts prepared using the incipient wetness technique. The effect of reaction conditions and catalyst parameters has been investigated. The supported gold palladium nanoparticles produce methyl hydroperoxide as the primary reaction product which is subsequently converted to methanol with high selectivity, ca. 40–70 %. The selectivity to methanol is influenced by the oxidation state the palladium component of the catalyst. In contrast to homogeneous gold and palladium catalysts the heterogeneous gold palladium nanoalloys are reusable and affords high oxygenate selectivity (ca. 90 %).     

Study of Deactivation of Pd(OH)2/C Catalyst in Reductive Debenzylation of Hexabenzylhexaazaisowurtzitane

The conversion of hexabenzylhexaazaisowurtzitane (HBIW) to 2,6,8,12‐tetraacetyl‐4,10‐dibenzyl‐2,4,6,8,10,12‐hexaazaisowurtzitane (TADB) is the major challenge in the production of hexanitrohexaazaisowurtzitane (HNIW) which only proceeds over supported palladium catalyst in a reductive debenzylation reaction. The catalyst is quickly deactivated during the debenzylation reaction. In this study, the change in Pd content in the catalyst during the reaction was measured. It was demonstrated that a portion of the palladium particles in the catalyst was leached during the reaction. The H₂ chemisorption isotherm on the catalyst at 303 K showed that the volume of chemisorbed H₂ on spent catalyst was significantly less than that on fresh catalyst. The N₂ physisorption isotherm on the catalyst at 77 K revealed that the surface area of spent catalyst was less than that of fresh catalyst. Moreover, the FESEM‐EDS and TEM images and also wide‐angle XRD patterns demonstrated that the mean sizes of palladium crystallites and particles in spent catalyst were larger than those in the fresh catalyst. These results demonstrated that the leaching of palladium particles and the aggregation of palladium particles in catalyst play active roles in the deactivation of catalyst in the debenzylation of HBIW.     

碳材料负载钯催化Suzuki偶联反应的研究进展

过渡金属钯催化的Suzuki偶联反应是有机合成中的重要反应之一。固载钯催化剂具有制备简单、易分离、廉价等优点;碳材料具有大的比表面积、良好的孔结构、性质稳定、容易回收再生等优点,是理想的钯催化剂载体。综述了不同碳材料负载钯催化剂催化Suzuki偶联反应的研究进展。     

High-pressure synthesis of ethyl benzoate from chloro- and bromobenzene

When chlorobenzene was reacted with ethyl alcohol and carbon monoxide under pressure, the conversions of chlorobenzene to ethyl benzoate and benzoic acid under optimum reaction conditions were 31.3% and 30.1% respectively, with nickel naphthenate supported on silica gel (Ni:SiO₂ = 50:50) as the best catalyst. When bromobenzene was used instead of chlorobenzene, the best catalyst was found to be nickel iodide supported on silica gel (Ni:SiO₂ = 50:50), and the above conversions were 74.7% and 25.1% respectively under optimum reaction conditions.     

Palladium nanoparticles supported on polymer: An efficient and reusable heterogeneous catalyst for the Suzuki cross-coupling reactions and aerobic oxidation of alcohols

Polymer supported palladium nanoparticle catalyst was synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. This catalyst exhibits good activity and stability in Suzuki cross-coupling reaction of arylboronic acid with aryl halides and oxidation reaction of alcohols to corresponding aldehydes or ketones without over oxidation. After reaction, the catalyst can be separated by simple method and used many times in repeating cycles without considerable loss in its activity.     

High-pressure synthesis of ethyl benzoate from chloro- and bromobenzene

When chlorobenzene was reacted with ethyl alcohol and carbon monoxide under pressure, the conversions of chlorobenzene to ethyl benzoate and benzoic acid under optimum reaction conditions were 31.3% and 30.1% respectively, with nickel naphthenate supported on silica gel (Ni:SiO₂= 50:50) as the best catalyst. When bromobenzene was used instead of chlorobenzene, the best catalyst was found to be nickel iodide supported on silica gel (Ni:SiO₂ = 50:50), and the above conversions were 74.7% and 25.1% respectively under optimum reaction conditions.