金属盐对轻质油品氧化脱硫效果的影响

过氧化氢与低分子醛的氧化体系可以氧化脱除轻质油品中的部分硫,金属盐作为助剂有利于提高油品的脱硫率,尤其对硫醇硫和硫醚硫的脱除。以氧化法分别对三种类型硫-硫醇硫、硫醚硫和噻吩硫的模拟轻质油品进行脱硫实验,并考察四种不同金属盐的助脱硫效果,研究发现助剂SnCl4的作用最为显著。本文还考察了助剂的不同加入比例对脱硫率的影响,结果表明,硫醚硫的脱硫率与SnCl4加入量的大小正比关系比较明显;硫醇硫仅表现于脱臭率的增加;噻吩的硫原子参与芳香环共轭,与金属离子较难络合,因此助剂的加入对其脱除并没有明显效果。     

过渡金属添加剂对煤热解脱硫的影响

利用坩埚焦考察了过渡金属添加剂Fe、Cr和Mn的不同形态在焦化过程中对高硫焦煤中硫脱除的影响,并通过固定床热解实验考察了不同气氛下添加剂对煤热解脱硫及含硫化合物逸出的影响。结果表明,不同金属添加剂对煤中硫形态有不同影响,氧化性较高的Fe3+降低了煤中黄铁矿硫的含量,而其他金属添加剂对煤中硫形态影响不大。在模拟焦化过程中,铬系添加剂提高了热解脱硫率,而铁系和锰系添加剂降低了脱硫率;负载Cr3+的介休煤在不同气氛下的热解表明,氮气抑制了Cr的脱硫作用,显著地减少了含硫气体的生成量,并使煤中易脱除硫转化为稳定的有机硫;还原性气氛有利于Cr3+添加剂的脱硫作用,显著地增加了含硫气体的生成量;焦炉气和氢气下添加剂对热解脱硫及煤热解过程中含硫气体逸出的影响相似,焦炉气可以作为提高过渡金属添加剂脱硫性能的反应气体。     

高硫煤加氢热解脱硫的研究

以兖烟煤和在褐煤为考察对象，在加压固定床上压力为３ＭＰａ，温度从３５０－６５０℃范围内，研究了中氢热解以及氮气下热解过程中硫在半焦、焦油中的含量以及脱硫率和硫分布的变迁规律。实验表明，加氢热解比氮气下热解有着更好的脱硫作用，有地降低半焦中的硫含量。这种硫作用随煤 不同而不同，尤其受到煤中矿物质的显著影响。因此红庙煤加氢热解焦油的硫含量显著降低，半焦的硫含量随温度的同，先逐渐降低然后增加；而兖 煤一     

流化床燃烧过程中水煤浆硫分析出规律的研究

燃烧脱硫县有投资省、设备简单、脱硫剂价廉易得等优点,尤以流化床燃烧技术最能适应燃烧过程中添加石灰石或其它脱硫剂来实现脱硫。与流化床燃烧过程中煤的脱硫研究相比,对水煤浆的硫分析出规律的研究甚少。因此,本文作者用改进的ZCL自动测硫仪进行了不同流化床燃烧条件及不同煤浆中硫分析出规律的研究,并讨论了各因素对硫分析出规律的影响。     

提纯烟气脱硫渣载氧体煤化学链燃烧性能研究

基于电厂烟气脱硫渣,采用多步酸洗工艺加以提纯并制备获得CaSO_4载氧体。在高温固定床反应器上研究了还原反应温度、载氧体过量系数Φ、多次还原氧化循环等因素对提纯脱硫渣载氧体与煤化学链燃烧特性和气相硫演化规律的影响。结果表明,提纯脱硫渣载氧体有较高的反应活性,能够促进煤的充分转化;综合考虑碳的转化以及气相硫释放的抑制,最优反应工况中还原反应温度确定为900℃、载氧体过量系数Φ=1.0为最佳。经过五次还原氧化循环实验发现,随着循环次数的增加,CaSO_4副反应的进行及气相硫的不断释放,导致提纯脱硫渣载氧体循环反应活性略有降低,反应稳定性受到了一定的影响。     

高硫煤加氢热解脱硫的研究Ⅱ.反应条件对煤加氢热解脱硫的影响

本文采用红庙褐煤在加压固定床上，详细考察了不同反应条件对加氢热解脱硫的影响。研究结果表明：氢气流速的增加可以显著降低焦中的硫含量，增加脱硫率和硫在气相中的分布。氢气压力增加有利于增加煤中含硫化合物的加氢脱硫反应，提高脱硫率。加氢热解过程中的传质作用对脱硫率和硫分布也有重要影响。在一定的热解温度下，适当增加停留时间有利于氢气与含硫化合物的扩散接触，提高脱硫率。同时红庙煤加氢热解产生的焦油中的硫分布随各种反应条件的变化不大。     

提纯烟气脱硫渣载氧体煤化学链燃烧性能研究

基于电厂烟气脱硫渣，采用多步酸洗工艺加以提纯并制备获得CaSO₄载氧体。在高温固定床反应器上研究了还原反应温度、载氧体过量系数Φ、多次还原氧化循环等因素对提纯脱硫渣载氧体与煤化学链燃烧特性和气相硫演化规律的影响。结果表明，提纯脱硫渣载氧体有较高的反应活性，能够促进煤的充分转化；综合考虑碳的转化以及气相硫释放的抑制，最优反应工况中还原反应温度确定为900℃、载氧体过量系数Φ=1.0为最佳。经过五次还原氧化循环实验发现，随着循环次数的增加，CaSO₄副反应的进行及气相硫的不断释放，导致提纯脱硫渣载氧体循环反应活性略有降低，反应稳定性受到了一定的影响。     

粉尘对高温煤气脱硫反应的影响

研究了在400℃-550℃范围内粉尘对氧化铁高温脱硫剂的硫容和脱硫反应速度的影响。结果表明随着温度的升高,粉尘对脱硫剂的硫容和脱硫反应速度的影响增大。并利用收缩核模型计算比较了由于粉尘加入引起的H2S有效扩散系数的变化,发现有效扩散系数由于粉尘的作用,随温度升高显著降低。为脱硫除尘一体化工艺的开发提供了一定的理论依据。     

溴化钠水溶液体系中煤的电化学脱硫

煤炭脱硫技术包括:物理洗选、化学脱硫、生物脱硫、超声波脱硫和微波脱硫等[1～3]。物理洗选法脱硫最经济,但只能脱无机硫。生物、化学法脱硫不仅能脱无机硫,也能脱有机硫,但生产成本昂贵,距工业应用尚有一定距离。20世纪80年代出现的电化学脱硫技术是一种既能克服物理、化学等法的缺点,又能达到较好脱硫效果的洁净、温和的脱硫方法[4,5]。本文对电化学氧化脱硫进行了研究,探讨了电化学氧化法脱除煤中硫的适宜体系和条件。1　实验部分1 1　原料和试剂　实验采用山西平朔煤(Pingsucoal)为原料,煤样粒径小于0 125mm。对煤样进行硫分析,其…     

煤的乙醇超临界萃取脱硫

采用等温半连续超临界乙醇萃取方法对高变质程度的汾西主焦煤脱硫效果进行了考察。实验表明，煤的脱硫率随温度、时间和压力的增加而增大，脱总硫的选择率为２．８４～１４．０５。对于无机硫的脱除而言，温度比萃取时间更为有效。脱硫后残渣的发热量较原煤高。对于有机硫的脱除而言，当乙醇浓度为９５％时脱硫率最大。     

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.