甲烷部分氧化制合成气

对镍铜甲烷部分氧化催化剂的制备化学研究表明，在Ａｌ２Ｏ３、ＳｉＯ２、ｍｇＯ、ＴｉＯ２、Ｙ型分子筛等载体中，具有较好氢溢流功能的Ａｌ２Ｏ３所担载的镍铜催化剂，有最佳的反应性能、载体的产物溢物功能对反应中合成气的生成是有利的，对ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３催化剂，组分Ｃｕ的最佳含量是Ｃｕ／Ａｌ＝０．２／４（原子比），Ｎｉ／Ａｌ（原子比）在１／４－１．５／４范围内催化剂均保持最佳的反应性能，此时，甲烷转化     

甲烷部分氧化制合成气Ⅱ．镍系催化剂的反应性能

主要用第四周期金属元素的氧化物与Ａｌ２Ｏ３的复合氧化物催化剂上甲烷氧化的结果证实了催化剂设计中的预测：（１）催化剂首先应能解离活化甲烷，（２）催化剂要能较快地活化Ｏ２分子．只有同时满足这两个条件，催化剂才可能有较好的甲烷部分氧化活性．第四周期元素中只有镍具有这样的性质．Ｃｕ，Ｍｎ，Ｃｒ，Ｌａ，Ｃａ，Ｚｎ等氧化物的添加可明显提高Ｎｉ－Ａｌ２Ｏ３催化剂的甲烷部分氧化性能，其中Ｃｕ的助催化性能最好．催化剂ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３，ＮｉＯ－ＭｎＯ－Ａｌ２Ｏ３，ＮｉＯ－Ｃｒ２Ｏ３－Ａｌ２Ｏ３的反应活性和选择性顺序，与金属Ｃｕ，Ｍｎ，Ｃｒ上ＣＯ和Ｈ２脱附的顺序是一致的     

Ni-Cu-Al2O3催化剂的活性相及作用机理

对新鲜和７００℃反应过的Ｎｉ－Ａｌ和Ｎｉ－Ｃｕ－Ａｌ催化剂的ＸＲＤ、ＸＰＳ表征结果表明，新鲜ＮｉＯ－Ａｌ２Ｏ３催化剂体相中的ＮｉＯ，ＮｉＡｌ２Ｏ４经７００℃反应后转变成金属Ｎｉ，同时表面的镍物种由单一的ＮｉＡｌ２Ｏ４变为ＮｉＡｌ２Ｏ４，ＮｉＯ和金属Ｎｉ的混合物，经反应后ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３催化剂体相和表相中的ＮｉＡｌ２Ｏ４，ＣｕＡｌ２Ｏ４均转变成为Ｎｉ－Ｃｕ合金，这是此催化剂对甲烷部分氧化反     

Ni/Al2O3催化剂上甲烷部分氧化制合成气反应机理

用变应答／质谱在线检测技术研究了Ｎｉ／Ａｌ２Ｏ３催化剂上甲烷部分氧化制合成气的反应要理，研究结果指出，在常压９７３Ｋ条件下，Ｎｉ／Ａｌ２Ｏ３催化剂上甲烷部分氧化制合成气按直接氧化机理进行，Ｈ２和Ｃ烛甲烷部分氧化的一次产物，其主要反应可表示如下：１．ＣＨ４＋ｘＮｉ－ＮｉｘＣ＋２Ｈ２，２．Ｏ２＋２Ｎｉ－２ＮｉＯ，３．ＮｉｘＣ＋ＮｉＯ－ＣＯ＋（ｘ＋１）Ｎｉ。     

Ni／Al2O3上甲烷二氧化碳氧气转化制备合成气的研究

在固定床流动反应装置上，从活性组分的负载量，载体的焙烧温度、反应温度，空速等几个方面考察了Ｎｉ／Ａｌ２Ｏ３催化剂对ＣＨ４－ＣＯ２－Ｏ２转化制备合成气的催化活性，发现采用１１００℃焙烧的γ－Ａｌ２Ｏ３载体制备的镍负载量为９．１７ｗ％的Ｎｉ／Ａｌ２Ｏ３催化剂。     

CH4,CO2和O2制合成气反应中载体对Ni催化剂抗氧化性能的影响

在ＣＨ４、ＣＯ２ 催化氧化制合成气反应中, Ｎｉ／Ａｌ２Ｏ３ 催化剂在高温下生成ＮｉＡｌ２Ｏ４ 尖晶石,是导致催化剂失活的一个重要因素． 通过向载体（Ａｌ２Ｏ３）中添加各种氧化物, 使得催化剂的抗氧化性能得到改善． 并运用ＴＰＲ、ＸＲＤ对催化剂进行表征, 发现催化剂的抗氧化性顺序为： Ｎｉ／ＣａＯ－Ａｌ２Ｏ３ ＞ Ｎｉ／ＭｇＯ－Ａｌ２Ｏ３ ＞ Ｎｉ／ＣｅＯ２－Ａｌ２Ｏ３ ＞ Ｎｉ／Ｌａ２Ｏ３－Ａｌ２Ｏ３ ＞ Ｎｉ／Ｙ２Ｏ３－Ａｌ２Ｏ３ ＞ Ｎｉ／ＴｉＯ２－Ａｌ２Ｏ３＞ Ｎｉ／Ａｌ２Ｏ３＞ Ｎｉ／Ｆｅ２Ｏ３－Ａｌ２Ｏ３．     

Ni/Al2O3催化剂上甲烷部分氧化制合成气

本研究了Ｎｉ／Ａｌ２Ｏ３催化剂的表面特征以及其与ＣＨ４部分氧化制合成气反应性能的关系。ＴＰＲ，ＸＲＤ和评价结果表明，催化剂Ｎｉ组分含量在９．０％时反应性能最佳，反应过程中催化剂表面上部有部分镍氧化物在５２０～５４０℃就还原，反应条件实验表明，在１１．５２×１０＾５ ｍｌ．ｇ＾－１下，随着反应管外控制温度的升高，ＣＨ４转化率，ＣＯ和Ｈ２选择性及收率增加，在７００℃下，随着原料气空速的增加，ＣＨ４转     

甲烷在Ni/TiO_2催化剂表面的活化

考察了Ｎｉ／ＴｉＯ２催化剂甲烷部分氧化和二氧化碳重整制合成气的反应活性,实验表明,以ＴｉＯ２为载体的镍系催化剂对于甲烷部分氧化制合成气反应具有较好的活性,尤其对Ｈ２的选择性较高,对二氧化碳重整制合成气反应具有较好的低温反应活性．采用脉冲－质谱在线分析等技术,在无气相氧条件下向Ｎｉ／ＴｉＯ２催化剂脉冲ＣＨ４,发现甲烷在催化剂表面的活化（转化）及其氧化产物的选择性与金属催化剂表面氧的浓度密切相关．ＣＨ４与Ｎｉ／ＴｉＯ２催化剂作用过程中存在明显的氢溢流和氧溢流现象,可能是这种溢流效应使得Ｎ／ＴｉＯ２催化剂具有良好的反应活性和抗积碳性能．     

对称电场催化增强甲烷转化合成C_2研究(英文)

利用电场作用通过交流和直流等离子体在低温、常压和低功率下催化反应将甲烷直接转化为碳二烃（乙烷、乙烯、乙炔）。考察了在对称电场作用下催化剂的催化性能。实验结果表明,在交流电场作用下,碳二烃选择性差别不大;甲烷转化率的大小顺序为： ＭｎＯ_２／Ａｌ２Ｏ３＞Ｎｉ／Ａｌ２Ｏ３＞ＭｏＯ_３／Ａｌ２Ｏ３＞Ａｌ２Ｏ３＞Ｎｉ／Ａｌ２Ｏ３＞ＭｏＯ_３／Ａｌ２Ｏ３＞Ｎｉ／ＮａＹ＞Ｐｄ／ＺＳＭ－５＞Ｎｉ／Ｈ４Ｍｇ２Ｓｉ３Ｏ４＞Ｎｉ／ＺＳＭ－５＞Ｃｏ／ＺＳＭ－５＞无催化剂：在直流电场作用下,碳二烃选择性差别也不大（除Ｎｉ／ＮａＹ外）,甲烷转化率的大小顺序为： Ｎｉ／Ａ１２Ｏ３＞Ｎｉ／Ｈ４Ｍｇ２Ｓｉ３Ｏ４＞Ｎｉ／ＺＳＭ－５＞Ｃｏ／ＺＳＭ－５＞ＭｎＯ２／Ａ１２Ｏ３＞ＭｏＯ３／Ａ１２Ｏ３＞Ｎｉ／ＮａＹ＞无催化剂＞Ｐｄ／ＺＳＭ－５。     

Ni系列催化剂上甲烷直接氧化制合成气

采用固定床流动反应装置，考察负载型Ｎｉ系列催化剂在甲烷直接氧化制合成气反应上的催化活性．空速为５．０×１０５ｈ－１，ＣＨ４／Ｏ２＝２条件下，不同Ｎｉ含量的催化剂中，１５％Ｎｉ／Ａｌ２Ｏ３活性较好．利用ＴＰＤ和ＸＲＤ技术将催化剂引发温度与催化剂组成进行关联，并在７００℃下考察空速对催化性能的影响．随着空速的增加，ＣＨ４的转化率增加，７．０×１０５ｈ－１时达到最大，与此同时，ＣＯ的选择性一直增加．实验结果说明在非平衡体系中，ＣＯ和Ｈ２是由ＣＨ４直接转化而来，ＣＯ２是ＣＯ深度氧化的产物，在此基础上对催化剂过程的机理作了初步的探讨．     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.