Pd-Sn-K/SiO2催化剂上甲苯气相氧乙酰化反应

 在常规固定床流动反应体系中研究了Pd-Sn-K/SiO2催化剂上气/固相氧化条件下甲苯与乙酸一步合成乙酸苄酯的反应. 结果表明,金属态钯是催化甲苯氧乙酰化合成乙酸苄酯的高活性组分,锡化合物的存在可明显提高催化剂的活性. 催化剂的活性与制备方法密切相关,用H2将SiO2上负载的钯化合物还原之后再负载锡化合物所得催化剂的活性较高. XRD分析结果表明,钯还原前负载锡化合物所得催化剂的活性大幅度降低的原因在于Pd和Sn形成了金属间化合物. 使用Pd/SiO2质量比为0.015, K∶Sn∶Pd摩尔比为27∶3∶1的Pd-Sn-K/SiO2催化剂,在反应温度为180 ℃,混合原料气甲苯∶乙酸∶氧气∶氮气摩尔比为1∶4∶1∶4以及空速为 1680 h-1的条件下,甲苯转化率可达25.3%, 乙酸苄酯选择性为91%. 以TiO2和ZrO2代替SiO2载体,或以其它变价金属氧化物代替Sn氧化物助剂或金属钯,均未发现有更好的催化效果.     

介孔Ni/MgO催化剂催化水蒸气重整生物质油制氢

采用水热法制备了介孔MgO作为催化剂的载体,并制备了介孔Ni/MgO催化剂。利用N_2吸附-脱附、XRD、H_2-TPR等对样品进行表征,并考察了介孔Ni/MgO催化水蒸气重整糠醛、生物质油模型物和两种商用生物质油制氢的活性。结果表明,在介孔Ni/MgO催化剂催化水蒸气重整糠醛制氢反应中,随着反应温度的提高,水蒸气重整糠醛中糠醛的转化率、氢气的产率和氢气的选择性,都呈现递增的趋势。在反应温度提高到600℃时,糠醛的转化率和氢气的产率分别达到94.9%和83.2%。Ni/MgO催化水蒸气重整二组分模拟生物质油,糠醛/乙酸、糠醛/羟基丙酮制氢的反应中,氢气的产率分别达到87.3%和86.8%,均高于水蒸气重整糠醛反应中氢气的产率。由此表明,乙酸或羟基丙酮的存在,提高了模拟生物质油中主要有机物组分糠醛的转化率,并相应地提高了氢气的产率。在水蒸气重整商用生物质油制氢反应中,随着反应物水碳比(S/C(molar ratio)=5、10、15、20、25)的提高,主要有机物的转化率、氢气的产率和选择性呈现出增加的趋势。在水碳比为20时,两种生物质油的主要有机物组分(糠醛、乙酸和羟基丙酮)的转化率均可达90%以上,氢气的产率也达到81.0%以上。由此可知,Ni催化剂对于水蒸气重整商用生物质油也具有较高的催化活性。     

低水碳摩尔比条件下液化石油气高效预重整的Ni/CeO2/Al2O3 催化剂

 采用硝酸镍和硝酸铈水溶液共浸渍薄水铝石制备了 Ni/CeO2/Al2O3 催化剂, 并将其用于低水碳摩尔比条件下商用液化石油气 (LPG) 预重整反应. 考察了 Ni 含量和反应温度对催化剂性能的影响. 结果表明, 在 300~400 oC 和水碳摩尔比为 1.0 的条件下, 该催化剂具有很高的催化 LPG 预重整反应活性. 15%Ni/CeO2/Al2O3 催化剂在 350 oC, 3 000 ml/(g•h) 和水碳摩尔比 1.0 的条件下, 反应 105 h 后 LPG 转化率和产气组成均保持不变, 表现出较高的稳定性. 反应后催化剂表面没有明显的积炭.     

ZrxCe1－xO2催化剂催化湿式氧化乙酸的活性研究

采用共沉淀法制备了Zr_xCe_1－xO₂催化剂, 利用BET, XRD和XPS对其进行了表征, 并研究了催化剂催化湿式氧化乙酸的活性. 结果表明: Zr和Ce摩尔比为1∶9的催化剂催化湿式氧化乙酸时具有最好的活性, 当乙酸溶液的初始化学需氧量(COD)为5000 mg/L, 反应温度为230 ℃, 压力为5 MPa时, 120 min后, COD的去除率为76% . 催化剂具有良好的活性是因为在CeO₂中加入Zr能够增大催化剂的比表面积和表面缺陷氧的含量, 并最终加快了HO₂•自由基的产生, 从而提高了催化剂的活性.     

Cr掺杂对Cu-Ce复合催化剂催化甲醇水蒸气重整制氢的影响

采用浸渍法制备了不同Cr含量的Cr/Cu-Ce催化剂,通过N_2O滴定、H_2-TPR和XPS等表征,对其结构、性质和催化性能进行了探究。结果表明,Cr助剂会改变Cu-Ce催化剂的铜比表面积、CuO还原温度以及氧空穴含量。其中,添加3%Cr的催化剂的Cu比表面积较大,CuO还原温度较低,氧空穴较多,进而表现出优良的催化性能。当反应温度为533 K,n(水)∶n(甲醇)=1.2∶1,甲醇和水的进料量为0.072 mL/min时,其催化效率达100%,重整气体组分中的CO体积分数为0.15%。与未掺杂Cr助剂的催化剂相比,其催化效率提高了10%,重整气体组分中的CO体积分数降低了0.34%。     

Ru/ZrO2-CeO2催化剂催化湿式氧化乙酸和苯酚的研究

采用共沉淀法制备了ZrO2-CeO2颗粒载体,利用浸渍法制备了Ru/ZrO2-CeO2颗粒催化剂,采用BET、XRD、SEM、TEM等方法对其进行了结构表征,测定了其催化湿式氧化乙酸的活性,并以苯酚为模型物进行了动态试验.结果表明,Zr的添加抑制了CeO2晶粒的长大,增加了催化剂的抗热性能.当催化剂Zr、Ce摩尔比为1∶9,焙烧温度为300℃时催化剂活性最高,在200℃和4 MPa下,催化湿式氧化乙酸反应120 m in后,COD去除率可达99%.动态实验100 h内,苯酚与COD的去除率都保持在90%以上,催化剂具有很好的活性和稳定性.     

乙醇水蒸气重整Co/CeO2催化剂

 采用共沉淀法制备了Co/CeO2催化剂并将其应用于乙醇水蒸气重整制氢反应,考察了活性组分含量和焙烧温度对催化剂性能的影响. 结果表明,在原料气水∶乙醇∶N2摩尔比为3∶1∶16, 空速为40 L/(g·h)和反应温度为350～600 ℃的条件下, 经650 ℃焙烧的10%Co/CeO2催化剂对乙醇水蒸气重整制氢反应具有高活性和高选择性. 在500 ℃下进行的40 h稳定性测试中,该催化剂上的乙醇转化率始终接近100%, 反应后气体中的H2含量保持在65%左右. X射线衍射表征结果显示,焙烧后催化剂的主要物相组成为Co3O4和CeO2, 二者之间存在相互作用. Co/CeO2催化剂中钴的主要存在形式包括小晶粒的钴氧化物、大晶粒Co3O4和进入CeO2晶格的钴,Co3O4含量和焙烧温度的改变可影响催化剂中钴的存在形式. 由催化剂中高分散小晶粒的钴氧化物还原所得的金属钴是关键的活性组分.     

烷氧基化法一步合成乙酸乙二醇单乙醚酯的反应研究

采用具备酸碱双活性位的复合金属氧化物固体催化剂,催化乙酸乙酯(EA)、环氧乙烷(EO)的羧酸酯乙氧基化反应,合成乙酸乙二醇单乙醚酯(CAC)。探索了铝镁锆、铝锌锆等7种不同类型的三金属复合氧化物对EA乙氧基化反应的影响,并研究了EA乙氧基化反应中原料配比、反应温度、催化剂用量等对EO转化率、CAC产率的影响。实验结果表明,铝镁锆复合金属氧化物催化剂具有较高的催化活性,在EA∶EO原料摩尔比为4∶1、反应温度120℃、催化剂用量为1.5(wt)%时,EO转化率为88.3%,CAC产率为43.5%,乙酸二(三)乙二醇单乙醚酯(DCAC,TCAC)产率分别为26.7%和11.4%。     

烷氧基化法一步合成乙二醇乙醚乙酸酯的反应研究

采用具备酸碱双活性位的复合金属氧化物固体催化剂,催化乙酸乙酯(EA)、环氧乙烷(EO)的羧酸酯乙氧基化反应,合成乙酸乙二醇单乙醚酯(CAC)。探索了铝镁锆、铝锌锆等7种不同类型的三金属复合氧化物对EA乙氧基化反应的影响,并研究了EA乙氧基化反应中原料配比、反应温度、催化剂用量等对EO转化率、CAC产率的影响。实验结果表明,铝镁锆复合金属氧化物催化剂具有较高的催化活性,在EA∶EO原料摩尔比为4∶1、反应温度120℃、催化剂用量为1.5(wt)%时,EO转化率为88.3%,CAC产率为43.5%,乙酸二(三)乙二醇单乙醚酯(DCAC,TCAC)产率分别为26.7%和11.4%。     

ZrxCe1－xO2催化剂催化湿式氧化乙酸的活性研究

采用共沉淀法制备了Zr_xCe_1－xO₂催化剂, 利用BET, XRD和XPS对其进行了表征, 并研究了催化剂催化湿式氧化乙酸的活性. 结果表明: Zr和Ce摩尔比为1∶9的催化剂催化湿式氧化乙酸时具有最好的活性, 当乙酸溶液的初始化学需氧量(COD)为5000 mg/L, 反应温度为230 ℃, 压力为5 MPa时, 120 min后, COD的去除率为76% . 催化剂具有良好的活性是因为在CeO₂中加入Zr能够增大催化剂的比表面积和表面缺陷氧的含量, 并最终加快了HO₂•自由基的产生, 从而提高了催化剂的活性.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.