Pb、Bi改性Pd催化剂合成芳樟醇

反应温度30～75℃,压力0.5～1.0MPa,以Pb、Bi改性的Pd催化剂合成芳樟醇,当催化剂中w(Pd)=1%时,脱氢芳樟醇转化率为99%～100%,合成芳樟醇选择性大于98%。产品经减压精馏,w(芳樟醇)>98%,收率为80%～90%。以Lindlar催化剂合成芳樟醇,脱氢芳樟醇转化率为99%～100%,合成芳樟醇选择性为95%～97%。     

去氢芳樟醇加氢催化剂的制备与活性评价

采用浸渍法制备了Pd-Pb-Bi/CaCO3催化剂,考察了钯质量分数对催化剂活性的影响,并对催化剂加氢性能进行了评价。结果表明,钯质量分数为1.5%的催化剂活性较高,在反应温度为60～65 ℃,系统压力为0.6 MPa,催化剂用量为原料质量的0.5％,去氢芳樟醇转化率大于99%时,芳樟醇选择性大于96%,催化剂套用7次后,利用ICP对使用前后催化剂的组成进行分析后,根据反应结果分析了Pb和Bi对加氢反应的作用。     

芳樟醇减压精馏残液合成四氢芳樟醇工艺

以脱氢芳樟醇选择性加氢合成芳樟醇减压精馏残液为原料,在不同反应温度、氢气压力、催化剂用量等实验条件下,考察Lindlar催化剂、RaneyNi、5%Pd/C对残液中的芳樟醇、二氢芳樟醇加氢反应合成四氢芳樟醇的影响,通过GC/MS、1HNMR确定了反应主要产物。以5%Pd/C为催化剂,反应温度90～92℃,氢气压力2.0MPa,反应时间4h,m(催化剂)∶m(芳樟醇减压精馏残液)=1.2∶100,残液中的芳樟醇、二氢芳樟醇质量分数分别为59.2%、38.3%,残液合成四氢芳樟醇反应收率96.3%,反应液中的四氢芳樟醇质量分数为96.5%。     

高纯四氢芳樟醇的研究

在一定条件下,芳樟醇可高选择性地氢化成四氢芳樟醇,氢化选择性与催化剂的特性、氢化温度及芳樟醇来源有关。在适宜的氢压及搅拌条件下,改变催化剂的特性、反应温度及使用不同来源的芳樟醇能提高加氢产物中四氢芳樟醇的含量。以日本进口的合成芳樟醇（含量98.7%）为原料,采用W-6型雷尼镍为催化剂,在（60±10）℃、1～3 MPa氢压的条件下进行氢化,所得四氢芳樟醇含量为98.7%,选择性为100%。     

选择性加氢合成芳樟醇催化剂的研究进展

综合介绍了选择性加氢合成芳樟醇催化剂的国内外研究情况。催化加氢合成芳樟醇，主要采用固体催化剂，活性组分大多为Pd，载体通常为CaCO3、BaSO4、Al2O3、金属材料，改性剂为铅、铋、锰或吡啶、喹啉、含硫化合物，转化率可达100％，选择性在98％以上。     

钛酸异丙酯催化脱氢芳樟醇合成柠檬醛

以钛酸异丙酯为主催化剂,氯化亚铜为助催化剂,在氮气保护和有机酸的存在下,研究了脱氢芳樟醇经迈耶－舒斯特重排反应合成柠檬醛.优化的反应条件如下:n(钛酸异丙酯):n(氯化亚铜)=4:1,催化剂(钛酸异丙酯+氯化亚铜)和对甲基苯甲酸的用量分别为原料脱氢芳樟醇质量的3.5%和10%,在110℃下反应3h,得到脱氢芳樟醇的转化率为98.8%,生成柠檬醛的收率为88.4%.采用水蒸气蒸馏的方法分离反应液,得到纯度≥97%的柠檬醛,采用FTIR对产物进行表征,确定了产品柠檬醛中所含有的主要杂质.最后,探讨了脱氢芳樟醇合成柠檬醛的反应机理.     

钒化合物催化芳樟醇酯化异构制取香叶醇、橙花醇

以钒化合物作催化剂与硼酸酯为介质组成催化体系,由芳樟醇异构制取香叶醇和橙花醇,分别考察了反应温度、时间、介质等因素对反应的影响。结果表明,在适宜的反应条件下,芳樟醇的转化率达 70. 8%,选择性 98. 2%。     

响应曲面法优化芳樟醇合成香叶基丙酮的工艺研究

在Na₂HPO₄·12H₂O催化剂作用下,通过Carroll反应,以芳樟醇与乙酰乙酸乙酯为原料合成了香叶基丙酮。考察反应温度、反应时间、物料摩尔比、催化剂用量对香叶基丙酮产率的影响。结果表明,优化出香叶基丙酮合成工艺为：反应温度174℃,反应时间7 h,芳樟醇与乙酰乙酸乙酯摩尔比1∶2.0,催化剂用量为3%(以芳樟醇质量为基准)。优化工艺条件下,香叶基丙酮的产率达89.1%。     

芳樟醇选择加氢制备二氢芳樟醇

用常用的Pd／C或RaneyNi催化剂对芳樟醇实现了选择加氢,以98％以上的收率得到二氢芳樟醇。     

脱氢芳樟醇催化重排合成柠檬醛试探

选用廉价易得的催化剂钛酸丁酯和氯化铜 ,以脱氢芳樟醇为原料 ,在酸性条件下对催化重排制取柠檬醛进行了探索。考察了反应温度、反应时间、催化剂加入量等因素对脱氢芳樟醇转化率和反应收率的影响 ,得到最佳反应温度、时间和催化剂用量分别为 12 5℃、3小时和 2 .5 % (重量计 )。相应转化率 90 %以上 ,收率达 73.1% ,接近钼催化剂的水平。     

乙醇蒸汽重整Pd/γ-Al2O3催化剂制氢

通过对不同Pd负载量、温度以及寿命的考察,评价了负载型Pd/γ-Al2O3催化剂在乙醇蒸汽重整制氢的催化反应中的性能。试验表明较高的Pd负载量或者较高的反应温度可以获得理想的氢气选择性。在650℃反应温度下,对含Pd为5%(质量分数)的Pd/Al2O3催化剂进行考察获得了最高的氢气选择性136%。而且在反应温度为750℃条件下,含Pd为1%(质量分数)的Pd/Al2O3催化剂对氢气的选择性可以达到110%。通过NH3-TPD,TGA分析手段对催化剂进行表征分析。     

钌钯双金属催化剂催化L-氨基丙酸加氢特性

通过添加金属Pd对Ru/C催化剂进行改性,提高了L-氨基丙酸加氢制备L-氨基丙醇的收率和光学选择性。采用ICP-MS、XRD、TEM和XPS对所制备的催化剂进行了系统的表征,结果表明：RuPd物种在载体活性炭上分散均匀粒径较小,Pd原子的加入可显著改善Ru的电子特性,调变不同的RuPd原子比,可影响RuPd物种的存在状态,进而影响L-氨基丙醇的收率和光学选择性。在氨基丙酸浓度为0.9 mol·L^-1,磷酸浓度0.69 mol·L^-1,催化剂用量为反应物的20%,反应温度95℃,压力4.0 MPa的反应条件下,RuPd原子比为3∶1时催化剂表现出最好的催化性能,L-氨基丙醇的收率达到99.7%,产品的光学选择性同样达到了99.7%,同时催化剂能循环使用20次,催化性能基本保持不变。     

FeCrAl金属壁载PdZn/Al2O3催化剂上甲醇水蒸汽重整制氢

采用等体积浸渍法制备了不同Pd负载量和不同Pd与Zn物质的量比的PdZn/Al<,2>O<,3>甲醇水蒸汽重整颗粒催化剂,结果表明,Pd负载质量分数9.25%和n(Pd):n(Zn)=0.24的催化剂表现出较佳的催化性能.XRD表征表明,由于生成了较大的Pd-Zn合金粒子,从而有利于甲醇重整反应的进行.制备了金属壁载型...     

Benzylacetate synthesis by oxyacetoxylation of toluene on Pd–Bi binary catalyst

Benzylacetate synthesis from toluene, acetic acid and oxygen on Pd–Bi binary catalyst was studied in the liquid phase. By incorporation of Bi with Pd, both the activity and selectivity were improved. Especially better stability was obtained with the catalyst having Pd/Bi = 3. Deactivation of the catalyst was investigated in detail by XRD, XPS, TEM, elemental analysis, EPMA and so on. Comparing the used catalyst with the fresh one, it was indicated that the main cause of deactivation was the dissolution of Pd into the reaction mixture from the most outer surface of the catalyst. By adopting proper reaction conditions to prevent the Pd dissolution, the catalyst having Pd/Bi = 3 was suggested to be used as an industrial catalyst. This revised version was published online in June 2006 with corrections to the Cover Date.     

Selectivity controlling in the hydrogenation of 1,3-butadiene on Tl-modified Pd catalyst

The selectivity and reactivity in the hydrogenation of 1,3-butadiene catalyzed by Tl-modified 5 wt% Pd/Al₂O₃ catalysts vary with amounts of Tl loading and with the reduction temperatures, that is, the main product was 1-butene and trans-2-butene for values of Tl loading of 0.5 and 2 in Tl/Pd atomic ratio, respectively, when the catalysts were reduced at 673 K. 1,3-butadiene was hydrogenated selectively towards 1-butene and trans-2-butene when the Tl modified 5 wt% Pd/Al₂O₃ catalyst of Tl/Pd = 2 was reduced at 300 and 373 K or above, respectively. On the catalyst with Tl/Pd = 2 reduced at 373 K or above, the butenes formed are not hydrogenated to butane, even after a long reaction time. These results suggest the formation of Pd-Tl alloy or intermetallic compounds during the reduction procedure which is responsible for the selectivity controlling in the reaction. TPR and XRD results were in consistence with the reaction data.     

Pd/HZSM-5催化剂催化加氢丙酮合成甲基异丁基酮

以HZSM-5为载体,采用浸渍法制备系列Pd/HZSM-5催化剂,在高压连续流动固定床反应器中考察Pd/HZSM-5催化剂催化加氢丙酮一步法合成甲基异丁基酮性能,并对工艺条件进行优化。结果表明,当HZSM-5载体上Pd负载质量分数为0.5%时,在反应温度140 ℃、氢压1 MPa、空速0.48 h^-1和氢酮物质的量比为1条件下,Pd/HZSM-5催化剂催化活性较高,丙酮转化率为45.91%,甲基异丁基酮选择性为94.33%。采用XRD、H₂-TPD、SEM、EDS和TGA等对催化剂进行表征,结果表明,负载质量分数0.5%的Pd在HZSM-5分子筛表面分散均匀,且0.5%Pd/HZSM-5催化剂具有较高氢吸附能力,失活的主要原因为催化剂表面积炭,采用流化床反应器取代传统的固定床反应器可以很好的解决催化剂积炭问题。     

Preparation of catalyst Pd-Au/1cTiO2/SiO2 and epoxidation of olefins

Two kinds of Pd-Au bimetallic nanocatalysts (0.01% Pd-Au/1cTiO₂/SiO₂ and 0.05% Pd-Au/1cTiO₂/SiO₂) were prepared by using 1cTiO₂/SiO₂ as support, which had a single layer TiO₂ thin film on SiO₂ substrate by atomic layer deposition (ALD) technique. Deposition of Au and Pd on 1cTiO₂/SiO₂ was carried out by means of deposition precipitation and impregnation. Au loading of the two catalysts was both 0.01%(mass), and the Pd loading were 0.01% and 0.05% respectively. The prepared catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS), and the morphology of nanoparticles, the chemical valence state and composition of Pd and Au elements were determined. The Pd-Au bimetallic nanocatalysts were used in the selective epoxidation of cyclohexene using oxygen as oxidant, and the conditions such as the reaction solvent, the type of co-reductant and the reaction temperature were screened. The applicability of the catalyst to different structural olefins was investigated under the optimized reaction conditions. For cyclic olefins, the substrate conversion rate is greater than 95%, and the epoxy product selectivity is greater than 91%. After the catalyst is recycled 5 times, the catalytic activity and reaction selectivity remain unchanged.     

Pd-Au/1cTiO2/SiO2催化剂的制备及其烯烃的环氧化性能

使用沉淀沉积法及溶液浸渍法分别将Au和Pd纳米粒子负载在原子层沉积法制备的1cTiO₂/SiO₂载体上,制备出两种不同Pd负载量的Pd-Au双金属活性中心纳米催化剂。采用TEM、EDX、XPS对所制备的催化剂进行了详细的表征,确定了纳米粒子的形貌、Pd-Au元素的化学价态和组成。测试了该类催化剂在以氧气为氧源的环己烯环氧化反应中的活性和选择性,并对反应溶剂、共还原剂种类、反应温度等条件进行了筛选。在优化后的反应条件下考察了该催化剂对不同结构烯烃的适用性。对于环状烯烃,底物转化率均大于95%,环氧产物选择性均大于91%。催化剂在循环回收5次后,催化活性和反应选择性保持不变。     

Effect of Palladium on Iron Fischer–Tropsch Synthesis Catalysts

Studies were conducted to investigate the effect of Pd on the Fischer–Tropsch Synthesis (FTS) selectivity, activity and kinetics as well as on the water–gas shift activity of an iron catalyst. Two palladium promoted catalysts (Pd0.002/Fe100 and Pd0.005/Fe100) were prepared from a base Fe100/Si5.1 (atomic ratio) catalyst. Results of FTS over the two palladium promoted catalysts were compared to those obtained from the K/Fe/Si base catalyst and a Cu/K/Fe/Si catalyst. The results indicate that Pd enhanced the FT activity while the selectivity for CO₂ and CH₄ changed little compared to the results for the base catalyst and the Cu promoted catalyst. Palladium promotion had a negative effect on the C₂—C₄ olefin to paraffin ratio. Pd promotion led to a higher WGS rate than the other two catalysts at high syngas conversions. A higher WGS rate compared to the FTS rate was obtained only for the Pd promoted catalysts. The FTS rate constant for the Pd promoted catalyst is higher than the base catalyst but lower than for the Cu promoted catalyst.     

Co - Bi2(MoO4)3应用于环己烷催化氧化制环己酮和环己醇

采用沉淀法合成了Co - Bi2( MoO4)3催化剂,以环己烷的液相选择性氧化为探针反应评价催化剂的性能,结果表明,金属原子数的最佳配比为n( Mo)∶ n( Bi)∶ n( Co) =1.5∶1.0∶0.2,在一定转化率前提下,有效减缓Bi2( MoO4)3氧化性的同时,环已酮和环己醇选择性分别达到74.1％和22...