Cu-SSZ-13/堇青石整体式催化剂的原位合成及其NH3选择性催化还原NO性能

采用水热合成技术, 在堇青石蜂窝陶瓷载体上原位合成了SSZ-13分子筛, 并借助X射线衍射(XRD)和场发射扫描电子显微镜(FESEM)等手段对其进行表征. 在此基础上, 研究了合成时间对催化剂结构和机械性能的影响. 另外, 使用固定床反应器测试了离子交换度为50%的Cu-SSZ-13/堇青石催化剂和Cu-SSZ-13催化剂水热老化前后的氨气选择性催化还原(NH₃-SCR) NO性能. 结果表明, 通过原位合成法制备的Cu-SSZ-13/堇青石催化剂在200-500 ℃ 的窗口温度内能达到80%以上的转化率, 并在300 ℃ 时达到96.4%的转化率. 在850 ℃水热老化12 h后, Cu-SSZ-13催化剂完全丧失了催化性能, 而Cu-SSZ-13/堇青石催化剂在300 ℃时仍然保持91%的转化率. 使用XRD和固体27Al 核磁共振(²⁷Al NMR)的方法, 研究了水热老化前后两种催化剂结构的变化, 结果表明, 当水热老化12 h 后, Cu-SSZ-13 基本丧失了SSZ-13 结构特征峰, 而Cu-SSZ-13/堇青石仍然保持了一定的SSZ-13 骨架结构. 证明了通过原位合成法制备的Cu-SSZ-13/堇青石催化剂具有较好的抗水热老化性能.     

生物质焦油模型化合物催化转化实验研究

以苯和甲苯为焦油的模型化合物,在固定床反应器上研究了堇青石和白云石两种催化剂作用下,温度、蒸汽量和空速对焦油催化转化的影响。结果表明,苯和甲苯的转化率都随温度的提高和空速的降低而升高。在堇青石和白云石催化作用下,甲苯在裂解温度900℃,S/C摩尔比为1.5时转化率最高,转化率均达到95%。苯在裂解温度900℃,S/C摩尔比为1.0时转化率最高,转化率分别为61%和53%。蒸汽量的增大有助于裂解气体成分的调整。堇青石稳定性实验表明,积炭是造成催化剂活性降低的重要原因。     

稀土金属氧化物改性整体式钌基氨合成催化剂的制备和性能的研究

研究了稀土金属氧化物La2O3，CeO2，Pr2O3，Nd2O3和Sin2O3对Ru-Bd堇青石催化剂的活性的影响。利用BET，BJH，SEM，XRD，CO化学吸附等测试手段对催化剂进行表征，并对催化剂的反应性能进行评价。SEM测试结果显示La2O3呈“虫卵状”聚集在茧青石表面，而CeO2呈立方CaF2型均匀的覆盖在堇青石表面，Ru粒子呈“孤岛状”均匀地分散在铈改性的堇青石载体表面。茧青石载体经CeO2改性后，催化剂的比表面积、比孔容积以及中、微孔数量均有所提高，孔径分布也得到了明显改善。活性数据显示，适量的稀土金属氧化物均能促进Ru-Ba/堇青石催化剂的活性，其中CeO2的改性效果最好，在10MPa，475℃，5000h^-1时CeO2改性的Ru-Ba／茧青石催化剂的氨合成转化率达到9．9％。研究了CeO2对氨浓度随温度、压力、空速变化趋势的影响。     

Cu/ZnO@H-β-P催化剂在合成气制备液化石油气反应中的性能研究

采用共沉淀法制备Cu/ZnO催化剂、水热合成法制备H-β分子筛、通过物理包膜法制备了具有核壳结构的Cu/ZnO@H-β-P催化剂,并用于合成气制备液化石油气(LPG)反应。通过XRD、NH3-TPD、BET和SEM-EDS等手段对催化剂进行了表征,利用固定床连续反应装置对催化剂进行了活性评价。结果表明,Cu/ZnO@H-β-P催化剂是具有中孔的核壳结构材料,其协同作用打破了原有的热力学平衡,促进了甲醇→DME→LPG串联反应的连续进行。与物理混合的Mix-Cu/ZnO-H-β催化剂相比,Cu/ZnO@H-β-P催化剂的CO转化率和LPG选择性更高,空速和反应温度对催化剂活性影响明显,最佳空速和反应温度分别为2 400 h~(-1)和350℃。使用Cu/ZnO@H-β-P催化剂在最佳条件下进行合成气制备LPG反应,CO转化率达到了57.22%,LPG选择性达到了60.52%。     

合成气一步法制备二甲醚核壳结构催化剂的制备及其反应性能

以生物质(葡萄糖、蔗糖、淀粉)为模板剂,通过水热合成法制备具有核壳结构的CuO-ZnO-Al₂O₃@Al₂O₃复合催化剂,该催化剂以甲醇合成催化剂CuO-ZnO-Al₂O₃为核,甲醇脱水催化剂Al₂O₃为壳.SEM-EDS对催化剂核壳结构的表征发现,通过改变水热合成温度和合成时间可以调变催化剂中Al₂O₃壳层的厚度.将该复合催化剂用于合成气直接制备二甲醚的反应,在空速1 500 mL/(h·g_cat)、温度260 ℃、压力5.0 MPa的条件下,CO转化率和二甲醚选择性分别达到35.2%和61.1%.     

铈改性CuMn/Al2O3/堇青石整体催化剂的甲苯催化燃烧性能研究(英文)

本研究以堇青石为载体,采用超声浸渍法制备了一系列CuMnCe_x/Al₂O₃/堇青石整体式催化剂,同时,通过N₂吸附-脱附、XRD、SEM、EDX、H₂-TPR、O₂-TPD、XPS和EPR等方法对样品的物理、化学性质进行了系统的表征分析。实验结果表明,CuMnCe_x/Al₂O₃/堇青石整体式催化剂中的Ce含量明显影响甲苯催化燃烧性能。其中,CuMnCe₂/Al₂O₃/堇青石整体式催化剂对甲苯氧化具有最高活性,当甲苯浓度为1 g/L、空速为78000 mL/(g·h)、温度为263℃时甲苯转化率达到90%,究其原因为CeO₂在CuMnO_x上分散均匀,不仅提高了氧空位的浓度和氧物种的迁移率,还增强了催化剂的低温还原性。同时,CuMnCe₂/Al₂     

金属-ZSM-5/堇青石整体式催化剂上稀燃汽车尾气的净化

 在原位合成的ZSM-5/堇青石整体式样品基础上制备了几种金属(Cu, In或Ag)改性的ZSM-5/堇青石催化剂,并将其应用于稀燃发动机尾气的净化. 结果表明, Cu-ZSM-5/堇青石催化性能最好,尾气中的三种主要污染物NOx, CO和HC可以同时得到净化. 用微量(0.02%)贵金属(Pd, Rh或Ir)对Cu-ZSM-5/堇青石进一步改性,所得催化剂对CO的净化能力大大增强,保持高NOx转化率的温度窗口也大大加宽,因而该催化剂在稀燃汽车尾气净化方面具有潜在的应用前景. 微量贵金属对Cu-ZSM-5/堇青石催化剂的改性作用也在文中进行了讨论.     

复合催化剂上合成气一步法制备液化石油气的研究

合成气一步法制备液化石油气(LPG)可在甲醇合成催化剂和分子筛组成的复合催化剂上实现.本实验选用与Y分子筛孔径相近的SAPO-5分子筛(0.73 nm × 0.73 nm)作为研究对象,在335 ℃、3.0 MPa、空速1 500 h^-1、Cu-Zn-Al/Pd-SAPO-5质量比为1/2的条件下获得了73.9%的CO转化率和73.0%的LPG选择性,该结果进一步证实了较大孔径的分子筛有利于LPG的合成.此外,研究结果还表明,合成气一步法制备LPG过程中甲醇/二甲醚向烃类的转化遵循烃池机理.     

CuxCe1-xO2-x/SBA-15/堇青石整体式催化剂及其CO催化氧化性能

以堇青石蜂窝陶瓷为载体,CuxCe1-xO2-x/SBA-15为催化活性组分,制备了一系列10%~60%Cu0.5Ce0.5O1.5/SBA-15/堇青石和50%CuxCe1-xO2-x/SBA-15/堇青石(x=0~1)整体式催化剂,采用低温氮吸附-脱附、XRD、XPS和H2-TPR对催化剂进行了表征,在微型固定床反应器中评价了催化剂的CO催化氧化活性。结果表明:整体式催化剂仍然保持SBA-15的介孔结构,催化剂中除了堇青石的物相外,还有CuO和CeO2物相,催化剂表面的Cu以Cu2+和Cu+两种状态存在,Ce以Ce4+状态存在,催化剂表面的氧化还原性能与Cu0.5Ce0.5O1.5的含量和Cu、Ce的比例有一定的关系,50%Cu0.5Ce0.5O1.5/SBA-15/堇青石催化剂具有最好催化活性,CO可以在140℃完全转化。     

Co-Ni2P/SBA-15/Cordierite整体式催化剂的制备及其二苯并噻吩加氢脱硫性能

用共浸渍法制备了Co-Ni2P/SBA-15前躯体,将其调制成活性胶后均匀涂覆到预处理后的堇青石载体上,程序升温还原后制备了一系列Co-Ni2P/SBA-15/堇青石整体式催化剂。采用XRD、N2吸脱附和XPS等对催化剂进行了表征,以1 wt%二苯并噻吩(DBT)/十氢萘溶液为模型化合物,在微型固定床反应器上对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,不同Co含量的Co-Ni2P/SBA-15/堇青石整体式催化剂中都形成了Ni2P相。Co的加入提高Ni2P/SBA-15/堇青石催化剂的比表面积和孔体积。Co含量为0.55wt%的Co-Ni2P/SBA-15/堇青石整体式催化剂有最好的二苯并噻吩加氢脱硫活性,在380℃,二苯并噻吩转化率能够达到98.8%。Co的加入能够提高二苯并噻吩直接加氢脱硫产物联苯的选择性。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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 substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.