非晶态Pd-B/Al2O3催化剂用于邻氯硝基苯加氢合成邻氯苯胺的研究

用化学还原法制得了Pd-B/Al2O3非晶态催化剂,并用于邻氯硝基苯液相加氢反应的研究.采用XRD、SEM、SAED等技术手段对催化剂进行了表征,表明Pd-B以超细颗粒的形式分散在载体上,并且明确了催化剂的非晶态性质、结构形态等.以邻氯硝基苯液相加氢为目标反应,对所制备催化剂的催化性能进行系统评价.在反应温度90℃、氢气压力1.0MPa的反应条件下,邻氯硝基苯的转化率达99.9%,邻氯苯胺的选择性达98.0%;在不加脱卤抑制剂的情况下,脱卤率小于2%,表明负载Pd系非晶态催化剂具有较好的邻氯硝基苯加氢活性及良好的选择性,优于Pd基晶态催化剂和Ni基晶态催化剂.从催化剂的微观结构、金属-载体相互作用、活性组分在载体表面的几何效应和电子效应等方面对非晶态催化剂响影响邻氯硝基苯加氢性能进行了讨论和解释.     

Pd/Fe_2O_3金属催化剂的制备及其催化还原邻氯硝基苯的研究

本文采用浸渍法制备了一系列负载型金属催化剂,进一步考察了它们催化邻氯硝基苯加氢反应的催化性能。研究表明:以纳米Fe_2O_3为载体所制得的Pd/Fe_2O_3金属催化剂用于邻氯硝基苯催化加氢反应具有较高的反应活性和选择性,反应转化率达90%以上,其中邻氯苯胺的选择性也达到90%以上。     

Pt/C催化剂催化邻硝基苯甲醚加氢制备邻氨基苯甲醚

以邻硝基苯甲醚为原料,采用Pt/C催化剂,通过液相催化加氢工艺合成邻氨基苯甲醚,研究不同反应条件对其转化率和选择性的影响,确定最佳工艺条件为,无水乙醇作溶剂、反应温度80℃、反应压力2 MPa、Pt/C催化剂用量0.01 g和反应时间2 h。相比传统硫化钠法和铁粉盐酸法等,催化加氢还原工艺可有效解决废水污染问题,提高产品收率和品质,降低生产成本,同时更易实现自动化生产,属于绿色新型工艺,具有良好的工业化前景。     

温和条件下Pt/MSU-S催化氯代硝基苯选择性加氢研究

采用乙醇还原法制备负载型Pt/MSU-S催化剂,采用X射线衍射、透射电镜、N2吸附-脱附对催化剂进行了表征。TEM表明,质量分数为0.5%的Pt在MSU-S载体上高度分散,Pt粒径在5 nm左右,无团聚现象。在常压反应温度30℃下分别考察了Pt/MSU-S催化剂对邻位、间位和对位氯代硝基苯催化加氢性能的影响,反应3 h,底物转化率为100%,邻氯苯胺的选择性达到96%,间氯苯胺和对氯苯胺的选择性达到98%。催化剂重复使用5次后仍然有很高催化活性和选择性。     

Pd/CNTs金属纳米催化剂的制备及其催化对氯硝基苯加氢性能

通过硝酸浸渍法对碳纳米管(CNTs)进行预处理改性,并采用乙二醇液相还原法制备Pd/CNTs纳米催化剂,通过XRD、TEM、BET、拉曼光谱、ICP等手段对其进行表征。结果表明,Pd/CNTs催化剂中Pd的负载量为0.9 wt%,Pd纳米颗粒均匀地分散在CNTs表面,粒径平均大小为5 nm。该催化剂用于对氯硝基苯的选择加氢反应,在常压、60℃下反应2 h,转化率为94.7%,选择性为89.2%。     

从邻氯硝基苯制造邻氟硝基苯的反应动力学

从邻氯硝基苯制造邻氟硝基苯的反应动力学徐敬柱，石祖芸，洪朝锽（浙江大学化工系）关键词邻氟硝基苯；相转移催化剂；反应动力学；卤交换反应１前言由于氟原子的引入，含氟有机化合物大多具有其它有机化合物所不能比拟的特点。含氟有机化合物独特而优良的性能引起人们对...     

负载型Pd/SBA—15催化剂催化性能研究

将负载型催化剂Pd/SBA—15用于催化邻氯硝基苯加氢。考察了反应温度、催化剂用量对Pd/SBA—15催化性能的影响,并考察了催化剂的使用寿命。实验结果表明,Pd/SBA—15催化剂表现出很好的催化性能,有望应用于工业生产。     

球形Pd催化剂应用于对氯硝基苯催化加氢

在聚乙二醇、环己胺和水组成的W/O乳状液体系中,用BH4-还原Pd2+制得了球形纳米Pd催化剂,并用XRD、XPS、TEM等方法表征了催化剂的结构、表面电子态和形貌等。通过催化对氯硝基苯加氢制备对氯苯胺来评价其催化性能。结果表明,该催化剂具备较高的催化活性和选择性,对氯硝基苯转化率达到100%,对氯苯胺的选择性达到99%以上,催化剂稳定性较好可以套用6次以上。     

金属添加剂对Ni-B非晶态合金催化剂邻氯硝基苯加氢性能的影响

研究金属添加剂（Cr、Mn、Fe、Co、Cu、Mo和Zn）负载的Ni-B非晶态合金催化剂催化加氢制备邻氯苯胺的影响。结果表明,适量的Zn、Cr和Mo能提高催化剂的活性和选择性,Mn对催化剂的活性和选择性影响不大,Fe、Co和Cu降低催化剂的活性。这与能和硝基形成多位吸附的单元镍以及电子因素有关。     

氯代硝基苯催化加氢制备氯代苯胺的研究进展

综述了近年来氯代硝基苯催化加氢制备氯代苯胺的研究进展。对铂基、钯基、钌基和镍基非均相催化剂的结构和催化性能进行了比较,讨论了催化剂助剂抑制脱氯副反应的机理。铂基催化剂活性和选择性较高,但是铂金属价格昂贵,且不能完全避免脱氯副反应;钯基和镍基催化剂活性好,但脱氯严重,通常需要引入脱氯抑制剂或使其形成非晶态合金提高产物的选择性;钌基催化剂的活性比铂基、钯基、镍基催化剂低,但选择性高,如何提高钌基催化剂的催化活性是今后的研究方向。     

Hydrogenation of phenol to cyclohexanone over Pd/MgO

Hydrogenation of phenol to cyclohexanone has been investigated in the temperature range 160–250°C on a series of Pd/MgO catalysts. At 160°C the orders of reaction were found on all catalysts to be about ?1 with respect to phenol and about + 1 with respect to hydrogen. On the basis of the kinetic results it is suggested that the rate determining step is the surface reaction between phenol and hydrogen adsorbed on the catalyst. An increase in the reaction temperature decreases the rate of reaction. This has been explained through a change of the orders of reaction which increase with temperature. Palladium dispersion does not influence the reaction mechanism. The specific activity was found to be independent of palladium particle size.     

苯甲酸加氢用钯碳催化剂的制备、失活及再生研究

研究了苯甲酸加氢用钯碳催化剂的制备、失活及再生。提出了钯碳催化剂的制备关键、加入甲烷化助剂可以延长钯碳催化剂寿命、利用超临界流体再生方法可以有效再生失活钯碳催化剂。     

负载Pt-B非晶态催化剂的氯代硝基苯加氢性能

分别以纳米碳管（CNTs）、SiO₂、γ-Al₂O₃和活性炭(AC)为载体,贵金属铂(Pt)为活性组分,用浸渍－化学还原法制备了负载型Pt-B非晶态催化剂,并以邻氯硝基苯的氢化为探针反应考察其催化性能。结果表明,Pt-B/CNTs催化剂具有较好的抑制脱卤的效果,分别较其他三种载体所得脱卤率降低了5.5倍、12.1倍和14.75倍。在SAED和TEM表征的基础上,从电子效应、催化剂粒子大小及载体的结构等方面解释了产生上述差别的原因。     

Ni-B/SiO2非晶态合金催化加氢制备邻氯苯胺

以水合肼和硼氢化钾为共还原剂制备了Ni-B/SiO2非晶态合金催化剂,并将其应用于邻氯硝基苯的催化加氢反应,较佳的制备条件是:温度=60℃,氢氧化钠0．1 g,水合肼3ml。使用该催化剂可使邻硝基氯苯的转化率达到100％,选择性达到98．20％,通过X衍射(XRD)和透射电镜观察(TEM)分析可知:该催化剂是一种纳米级非晶态合金。     

对羧基苯甲醛在Pd/AC催化剂上加氢反应表观动力学

在实验室间歇高压釜中对Pd/AC催化剂上对苯二甲酸(TA)加氢精制过程的对羧基苯甲醛(4-CBA)加氢反应进行了研究。考察了氢分压、反应温度、催化剂颗粒大小对4-CBA消失速率的影响,并采用幂函数动力学模型拟合得到了接近工业反应温度范围的表观动力学方程。结果表明,氢分压0.35~1.0 MPa时,对4-CBA加氢反应的速率影响很小,反应速率对氢分压可视为零级,随着温度升高和催化剂颗粒减小,4-CBA加氢反应速率显著增加;工业条件下的TA加氢精制过程存在着严重的内外扩散,4-CBA加氢反应的表观活化能为28 kJ/mol,对4-CBA的反应级数为1.23。     

Studies on the hydrogenation of cinnamaldehyde over Pd/C catalysts

The hydrogenation of cinnamaldehyde was investigated using a 5% Pd/C catalyst in a 250 cm³ stirred tank reactor and 500 cm³ autoclave. The experiments were carried out at 273–343 K and 0·1–1·1 MPa. Non-polar solvents, e.g. toluene, decane, methylcyclohexane, decalin, ether and heptane, and polar solvents such as methanol, ethanol, propan-1-o1, propan-2-ol, butan-1-ol and butan-2-ol were used to study the selectivity with respect to hydrocinnamaldehyde formation, the reaction kinetics and mass transfer. The additives, such as potassium acetate, ferrous chloride, ferrous sulphate and quinoline were incorporated into the catalyst in order to improve the catalyst selectivity, which was observed especially in the case of potassium acetate. © 1998 SCI     

对苯二甲酸精制钯炭催化剂载体活性炭的研究

分析了不同厂家生产的对苯二甲酸精制用钯炭催化剂载体活性炭的各种物性指标。实验结果表明,各种活性炭比表面相同时,其吸附量基本相近,但孔结构有较大差异,尤其是中孔孔容相差较大。中孔孔容增大,有利于钯炭催化剂分散度的提高和热稳定性增强.活性炭的表面基团对催化剂分散度也有影响,表面酸性基团含量增加,值化剂分散度提高.     

Hydrogenation reactions catalyzed by colloidal palladium nanoparticles under flow regime

A glycerol colloidal solution of palladium nanoparticles stabilized by PVP (PdPVP, mean diameter of 2.2 ± 0.8 × 10⁻⁹ m) was employed under flow conditions for hydrogenation reactions. After optimization, we selected the tube-in-tube flow reactor as the more suitable system for this catalytic process due to its ability to regulate the addition of hydrogen. PdPVP nanoparticles were synthesized and fully characterized ((HR)-TEM, PXRD, EA, and ICP) both in glycerol solution and at solid state. The reduction of different substrates, including nitrobenzene, 4-phenylbut-3-en-2-one, and isophorone, was achieved under relatively smooth conditions (5–7 × 10⁵ Pa of H₂) in short times (<600 s). Unfortunately, the reduction of 1-dodecene was not possible due to the faster isomerization reaction. The optimal effusion of hydrogen in the colloidal phase together with the catalytic efficiency of this system is noteworthy.     

Hydrogenation of citral over Ru-Sn/C

Citral has been hydrogenated over Ru-Sn/C catalysts. The Ru-Sn/C system has been studied as a function of the Ru/Sn ratio. Under the conditions used the carbonyl group and the conjugated double bond are hydrogenated. No products obtained from the hydrogenation of the isolated double bond are formed. Addition of tin on the Ru/C decreases the number of Ru active sites on the surface with a corresponding increase in the specific catalytic activity. A higher selectivity (>80%) to geraniol + nerol is observed on the samples with the highest Sn/Ru ratio. The higher selectivity and higher specific activity are attributed to an activation of the CO bond by tin ions.