焦炭与重质油共气化联产烯烃技术研究

针对中国乙烯、丙烯等低碳烯烃生产原料供需日益尖锐的矛盾和重质油利用技术的不足，提出焦炭与重质油共气化联产烯烃技术。阐述了焦炭与重质油共气化联产烯烃的技术原理及过程设计，并以固定床为反应器，焦炭和常压渣油为原料进行实验模拟。结果表明，当裂解温度为750℃~800℃，停留时间τ＜0.5s时，渣油在焦炭介质中裂解，其低碳烯烃含量最高；渣油在模拟气化裂解区、750℃下裂解时，得到出口气体中低碳烯烃（C2H4＋C3H6）、烷烃（CH4＋C2H6）及合成气（H2＋CO）的体积分数分别为20%、28%及46%。应用扫描电镜观察了焦炭介质表面上结焦生成物的形貌，发现通氧气后结焦生成物残留量较少。实验模拟结果证明，焦炭与重质油共气化技术可以制备低碳烯烃并联产合成气，且能有效地解决重质油裂解造成的结焦问题。     

A reactive analytical approach for the estimation of olefinic content in gasoline-range hydrocarbons by gas chromatography

The estimation of olefinic content in conversion processes such as the etherification of olefins in fluid catalytic cracking (FCC) gasoline is essentially required. Gas chromatography (GC) is the well-established method for the quantitative analysis of olefins in etherification processes. The current state-of-the-art GC methods employing highly specific long single capillary columns such as Petrocol-DH are being used for the analysis of gasoline-range hydrocarbons. However, the method needs many standard reference samples of respective components in a complex mixture of hydrocarbons, which limits the scope of the analytical method. The alternative approach followed by this investigation is based on the reactive method of the analysis of olefins in FCC light gasoline by subjecting them to hydrogenation and estimating the olefinic content by GC comparing the gas chromatograms of the original feed and hydrogenated product using a Petrocol-DH column. A decrease in the quantity and disappearances of the peaks are assumed as olefins, and their number and total composition is calculated. In this study the bromine number method is used to estimate the olefinic content for a comparison of results with the adopted proposed methodology. The adopted methodology quantitates olefinic content in FCC light gasoline, which is comparable with reported literature values and the bromine number method. With the availability of standard reference samples of some important major reactive olefins, the adopted methodology can also give component-wise analysis as well as total olefinic content in a single step in processes such as etherification. The methodology can be also useful in reactions in which the conversion of total olefinic content is needed such as hydration, esterification, and alkylation of olefins in a complex mixture of hydrocarbons apart from the etherification of olefins in FCC gasoline.     

Hydrogen-free homogeneous catalytic reduction of olefins in aqueous solutions

Herein we report a study involving the homogeneous catalytic reduction of unsaturated substrates in aqueous solutions or water-organic solvent mixtures. The reduction of olefins has been carried out in the presence of catalytic amounts of [Fe(CN)5NH3](3-) and excess of NH2OH, which under mild reaction conditions can be used to reduce carbon-carbon unsaturations without affecting carbonyl functionalities and aromatic rings. To explore the scope of the catalytic reduction, a wide variety of representative unsaturated substrates have been examined. The steric effects of the substituents on the carbon-carbon multiple bond as well as the regioselectivity and stereoselectivity of the catalyst have been studied. The deuterium kinetic isotope effect on the catalytic reduction of double bonds in olefins has been analyzed, and no significant kinetic isotope effect was found. Among the great advantages of this novel procedure for catalytic reduction are that hydrogen and high pressures are not needed, the catalyst is inexpensive and easily prepared, and water as well as water-organic solvent mixtures can be used as reaction media.     

Organic and polymer chemistry of electrophilic tri‐ and tetrasubstituted ethylenes

A survey of the spontaneous reactions of electrophilic olefins and nucleophilic olefins is presented as an area in which organic chemistry merges with polymer chemistry. The products include both small molecules and polymers, arising via tetramethylene biradical zwitterions that can cyclize or initiate polymerizations. Electrophilic tri‐ and tetrasubstituted olefins are particularly useful in delineating the transition from radical chemistry to ionic chemistry. A periodic table embodying these results enables predictions. Charge‐transfer complexes, although observed in many of these reactions, play no significant role. Various aspects arising from these investigations include new cationic initiators, Lewis acid catalysis, quinodimethane chemistry, and photochemistry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2845–2858, 2004     

Direct Synthetic Processes for Cyclic Carbonates from Olefins and CO<Subscript>2</Subscript>

This short review presents the recent developments in the direct synthesis of cyclic carbonates from olefins and CO₂. The straightforward synthesis of cyclic carbonates from olefins instead of epoxides, also called one-pot “oxidative carboxylation” of olefins, can be viewed as the coupling of two sequential reactions of epoxidation of olefins and CO₂ cycloaddition to epoxides formed. The facile synthetic approach would make carbonate synthesis simpler and even cheaper with industrial potential from environmental and economic points of view. Some progresses have been made on this direct synthetic reaction for cyclic carbonates with homogeneous and heterogeneous catalysts, however, this reaction system is still at a preliminary stage. Among the catalysts reported, only a few can be considered as effective for the direct oxidative carboxylation of olefins to cyclic carbonates. Thus active and selective catalysts should be explored to put the direct synthesis of cyclic carbonates into practical applications.     

β-Oxido膦叶立德的亲卤反应: 一种便利地合成三取代卤代烯 烃的方法

β-Oxido膦叶德作为新核试剂对一系列全卤代烷烃中的碳卤键能顺利地进行新卤进攻,生成α-卤代betaine中间体,并由此直接转化成相应的以Z式构型为主、反应产率中等的氯代、溴代或碘代的三取代烯烃。利用不同结构的鏻盐和醛缩合而? 傻摩?Oxido膦叶立德与全卤代烷反应,可以方便地合成一系列不同的结构的三取? 贝┨? $601$Aβ-OxidophosphoniumylidesasnucleophilesreactreadilywithvariousperhalalkanesviahalophilicattackonC—X(X=I,BrorCl)bondstoformaα-halosubstitutedbetaineintermediates,whichcanbetransformedinsituintoZ-isomersofchloro-,bromo-oriodo-substitutedolefinsasmajorproductsingoodyields.Thesenovelreactiosnmayaffordafacileroutetovarioustrisubsitutedhaloolefinsbymeansofβ-Oxidophosphoniumylidespreparedinsitufromvariousphosphoniumsaltsandaldehydes.     

Re-based heterogeneous catalysts for olefin metathesis prepared by surface organometallic chemistry: reactivity and selectivity

Herein we describe the catalytic activity of 1, a well-defined Re alkylidene complex supported silica, in the reaction of olefin metathesis. This system is highly active for terminal and internal olefins with initial rates up to 0.7 mol per mol Re per s. It also catalyses the self-metathesis of methyl oleate (MO) without the need of co-catalysts. The turnover numbers can reach up to 900 for MO, which is unprecedented for a heterogeneous Re-based catalyst. Moreover the use of silica as a support can bring major advantages, such as the possibility to use branched olefins like isobutene, which are usually incompatible with alumina-based supports; therefore, the formation of isoamylene from the cross-metathesis of propene and isobutene can be performed. All these results are in sharp contrast to what has been found for other silica- or alumina-supported rhenium oxide systems, which are either completely inactive (silica system) or typically need co-catalysts when functionalised olefins are used. Finally the initiation step corresponds to a cross-metathesis reaction to give a 3:1 mixture of 3,3-dimethylbutene and trans-4,4-dimethylpent-2-ene, and make this catalyst the first generation of well-defined Re-based heterogeneous catalysts.     

Toluene as a novel carrier of xanthates—preparation,use and surrogate of S-tri- and di-chloromethyl xanthates

Toluene has been identified as a novel carrier of xanthates. Their corresponding fragmentative precursors proved to behave efficiently in radical group transfer reactions. As examples, unprecedented S-tri/di-chloromethyl xanthates could be prepared, isolated and further used in radical additions to olefins. Their precursors (de-aromatized toluene upon which is grafted, at one end, a tri/di-chloromethyl-group and, at the other end, a dithiocarbonyl group) can also be used directly in the transfer of both groups to olefins. The re-aromatizing loss of toluene by radical initiated fragmentation of the precursors brings thus new opportunities to the chemistry of xanthates, exemplified here in the intermolecular additions to olefins of new S-tri/di-chloromethyl xanthates.     

大位阻烯烃不对称环氧化合成手性环氧化合物

采用大位阻的有机锂试剂或格氏试剂与卤代烯烃偶联合成了7种大位阻取代烯烃. 以Oxone(KHSO₅)作为氧化剂, 分别在D-果糖衍生酮和(2S,5R)-2-异丙基-5-甲基环己酮为催化剂的催化下, 将合成的7种大位阻取代烯烃转变成了7个大位阻的手性环氧化合物. 其中以D-果糖衍生酮的对映选择性最好, 当双键碳上含有3个取代基时, 对映选择性最高, e.e.值为96.8%~99.5%. (2S, 5R)-2-异丙基-5-甲基环己酮的对映选择性较差, 无论是一取代的烯烃还是三取代的烯烃, 其e.e.值均介于25.6%~34.1%之间.     

Synthesen durch Halbleiter‐Photokatalyse: Solare Chemie

Semiconducting zinc and cadmium sulfide powders are photocatalysts for novel organic syntheses. Due to their ability to generate reducing and oxidizing surface centers through light absorption, these powders can catalyze C‐C and C‐N coupling reactions via initial interfacial electron transfer with adsorbed substrates like olefins, imines, and 1,2‐diazenes. The thus obtained primary intermediates may be transformed to reduced and oxidized products, like in an electrochemical reaction, or combine to one unique addition product. In the latter case the addition of cyclic olefins to imines and 1,2‐diazenes affords novel homoallylamines and allylhydrazines. This is a good example for “green chemistry”, since no waste materials are produced and solar light is used as energy source. The eterogeneous sensitizer can be conveniently separated from the products by filtration.     

Palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups in scCO2

Product control of palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups can be achieved through modifying reaction conditions. When the oxidant, such as CuCl₂/O₂, benzoquinone/O₂ or O₂, was present in scCO₂, aerobic oxidation of terminal olefins goes smoothly. With enough MeOH and sufficient oxygen, acetalization preponderated over cyclotrimerization, while with little MeOH as co-solvent in scCO₂ or no MeOH in DMF and an appropriate pressure of O₂, cyclotrimerization of terminal olefins became the dominated reaction. When oxygen is absent and triethylamine was added into the reaction system, palladium-catalyzed C-N bond formation occurs to produce β-amino acid derivatives as the sole product.     

Synthesis of spirocyclic thiazolidinediones using ring-closing metathesis and one-pot sequential ring-closing/cross metathesis

A novel synthetic route to spirocyclic thiazolidinediones is reported by utilizing ring-closing metathesis (RCM). A selective cross metathesis (CM) of N-allyl azaspiro derivatives with different olefins has been demonstrated to prepare substituted azaspiro-[4.4]nonenediones. The X-ray crystal structure of a spirocyclic thiazolidinedione dimer is described, which has been prepared in two steps from thiazolidinedione using a one-pot sequential ring-closing and self metathesis. Cross metathesis proceeds smoothly with both electron rich and poor olefins. The symmetrical bis-thiazolidinedione spirocyclic system can be used as CM coupling partner with olefins. One-pot sequential RCM-CM has been developed for the synthesis of substituted spirocyclic compounds. The methodology allows a quick access to thia-azaspiro-[4.4]nonene and -[4.5]decene-dione ring systems from readily available starting materials which are not otherwise accessible.     

Catalytic intermolecular C-alkylation of 1,2-diketones with simple olefins: a recyclable directing group strategy

We describe the first example of Rh-catalyzed intermolecular C-alkylation of cyclic 1,2-diketones using simple terminal olefins as alkylating agents. Aminopyridine is employed as a recyclable directing group. First, it reacts with ketones to give enamines and delivers Rh to activate the vinyl C-H bonds in the same pot; second, it can be cleaved off and recovered via hydrolysis. A broad range of olefins can be utilized as substrates, including aliphatic, aromatic olefins and vinyl esters. The efficiency of this method is also demonstrated in the synthesis of a natural flavoring compound, 3-ethyl-5-methyl-1,2-cyclopentadione (one-pot 53% yield vs a previous four-step route 16% yield from the same starting material). This work is expected to serve as a seminal study toward catalytic ketone α-alkylation with unactivated olefins.     

A general model for selectivity in olefin cross metathesis

In recent years, olefin cross metathesis (CM) has emerged as a powerful and convenient synthetic technique in organic chemistry; however, as a general synthetic method, CM has been limited by the lack of predictability in product selectivity and stereoselectivity. Investigations into olefin cross metathesis with several classes of olefins, including substituted and functionalized styrenes, secondary allylic alcohols, tertiary allylic alcohols, and olefins with alpha-quaternary centers, have led to a general model useful for the prediction of product selectivity and stereoselectivity in cross metathesis. As a general ranking of olefin reactivity in CM, olefins can be categorized by their relative abilities to undergo homodimerization via cross metathesis and the susceptibility of their homodimers toward secondary metathesis reactions. When an olefin of high reactivity is reacted with an olefin of lower reactivity (sterically bulky, electron-deficient, etc.), selective cross metathesis can be achieved using feedstock stoichiometries as low as 1:1. By employing a metathesis catalyst with the appropriate activity, selective cross metathesis reactions can be achieved with a wide variety of electron-rich, electron-deficient, and sterically bulky olefins. Application of this model has allowed for the prediction and development of selective cross metathesis reactions, culminating in unprecedented three-component intermolecular cross metathesis reactions.     

烯烃在催化裂化催化剂上反应机理的初步研究

在自制的微反-色谱装置上,进行了单体烯烃和催化裂化汽油在不同条件下的催化裂化反应实验。对单体烯烃的裂化反应规律和汽油中的烯烃在半再生催化剂和待生催化剂上的催化裂化反应规律进行对比分析。结果表明,单体烯烃反应中,C6及C6以下的烯烃主要发生骨架异构和双键异构反应,氢转移和直接裂化反应发生的较少。C7以上的烯烃95%以上发生转化,高温下直接裂化生成C3、C4,氢转移和异构化比率较大。汽油中的烯烃转化主要集中在C7以上,烯烃之间存在一定的交互作用,单体烯烃的催化裂化反应规律可以初步预测汽油中烯烃的转化。催化剂上的结焦类型对汽油中的烯烃的转化方式没有影响。     

碳纳米管封装铁纳米粒子催化剂上CO加氢制低碳烯烃

由于石油资源的逐步枯竭,近年来费托(F-T)反应因其可以高效将煤、天然气和生物质等转化成液体燃料和高值化学品而越来越受到人们的关注。相比于Co, Ni和Ru等F-T催化剂, Fe基催化剂因其价格低廉,产物分布广而被广泛研究。以合成气直接制备低碳烯烃的F-T过程为例,铁基催化剂通常会因积碳和烧结的问题,而导致失活。因此,人们通常使用一些氧化物载体,比如氧化硅,氧化铝或者分子筛来分散并稳定铁粒子。但是这类氧化物载体通常与铁有非常强的相互作用,特别是在铁粒子较小的情况下,容易生成一些难于还原的硅酸铁和铝酸铁。而活性炭、碳纤维等惰性载体与铁的相互作用较弱,不足以稳定小的铁粒子在而反应过程中聚集。近来,我们组提出了利用石墨烯碳层封装过渡金属粒子作为催化剂,利用“穿透”的金属电子来催化反应,从而可以使活性中心和反应介质隔离,有效地增强了非贵金属催化剂的活性和稳定性。在此基础上,我们组和其他课题组的研究表明,一系列石墨烯碳层封装的非贵金属催化剂在燃料电池阴极氧还原反应,电催化析氢反应,染料敏化太阳能电池中的I3–还原反应以及催化氧化还原反应中都有着广泛的应用前景。这种材料中碳层不仅能在氧化气氛、酸性介质中保护包覆的金属,防止其被氧化或者腐蚀,还与包覆的金属有着较强的相互作用,可以促进非贵金属的电子向碳层表面的转移,有望在一些苛刻的反应条件下实现对贵金属催化剂的替代。本文进一步拓展了其在高温反应中的应用,发现豆荚状碳纳米管封装的金属铁纳米粒子在合成气制备低碳烯烃中可以有效防止金属铁纳米粒子的烧结和聚集,因此表现出优异的低碳烯烃选择性和催化稳定性。我们利用一步化学反应法合成了豆荚状碳纳米管封装的铁纳米粒子催化剂(Pod-Fe),并通过酸洗除去碳管外面裸露的铁粒子。透射电镜(TEM)和X射线衍射(XRD)表明酸洗后铁粒子被包覆在碳管内,并且呈金属态,而酸洗前,则还有大量的氧化铁粒子分布于碳管外部(FeOx/Pod-Fe)。将酸洗前后的两个催化剂用于固定床气相F-T反应中。通过调节空速和温度考察了它们的催化反应性能,结果表明两个催化剂在不同的反应条件下都有着良好的低碳烯烃选择性。不同反应温度下,它们表现出不同的变化趋势：Pod-Fe活性随着温度的升高而缓慢增长,至380 oC都没有明显的失活现象;而对于FeOx/Pod-Fe催化剂,随着温度的升高, CO的转化率先升高,在300 oC时达最高,但随着温度进一步升高,活性迅速降低,呈现一个火山型曲线。 TEM结果发现,反应后FeOx/Pod-Fe催化剂粒子上产生了很多杂乱的碳丝,并且铁粒子有着明显的聚集长大。而Pod–Fe催化剂即使在380 oC反应后,其形貌仍然保持完好,没有积碳产生,粒子也没有发生聚集和长大。进一步在320 oC下120 h的寿命试验发现, Pod-Fe催化剂的初始活性较低,但经20 h的活化阶段,活性会先增加后略有下降,20 h后趋于稳定。而FeOx/Pod-Fe催化剂在反应初始虽然表现出较高的活性,但是随着时间进行,活性迅速下降一半以上,最后趋于稳定。同时结合反应后TEM和XRD的结果发现碳管外部裸露的铁粒子会在反应过程中形成碳化铁物种,并随着反应进行产生聚集,并伴有大量积碳,导致活性迅速下降;而碳层的包覆对于铁粒子有着很好的稳定作用,使得铁粒子能够在高温反应中保持稳定,并且没有积碳的产生。由此可见石墨烯碳层可以有效保护其包覆的金属粒子,并且能够提高其在高温反应下的低碳烯烃选择性和稳定性。此类催化剂有望在一些苛刻条件下的多相催化反应中得到广泛应用。     

三苯甲基取代烯烃的环氧化研究

合成了6种三苯甲基取代烯烃. 以二甲基二氧杂环丙烷作为主要氧化剂, 在催化剂(R,R)-Salen Mn(III)的催化下, 进行不对称环氧化, 其不对称环氧化产物ee值较高(81%). 初步研究表明, 二甲基二氧杂环丙烷(DMD)和(R,R)-Salen Mn(III)的环氧化体系对于含亚甲基的三苯甲基取代的烯烃的氧化产率高但对映选择性差, 对于不含亚甲基的三苯甲基取代的烯烃的氧化产率低但对映选择性好.     

Sigma-Pi Rearrangements of Organotransition Metal Compounds

σ-Bonded organic groups in transition-metal complexes can rearrange to π-bonding ligands and vice versa: the classic example is the formation of π-arenechromium complexes from σ-arylchromium compounds. Rearrangements of this kind can be induced, inter alia, by reactions of the metal or of the ligand, as well as by migration or insertion of a ligand. Rearrangements play a role in many industrial processes, including the polymerization and isomerization of olefins and the hydroformylation of olefins.     

Diversity-oriented synthesis of tamoxifen-type tetrasubstituted olefins

A general synthetic scheme for tamoxifen-type tetrasubstituted olefins based on the novel Cu-catalyzed carbomagnesation across alkynyl(2-pyridyl)silane has been developed. A wide array of electronically and structurally diverse tetrasubstituted olefins can be prepared in a regiocontrolled, stereocontrolled, and diversity-oriented manner. Noteworthy features are that (i) the three aryl groups, which are believed to be important (essential) for anti-estrogenic activity, can be varied at will because they all stem from readily available aryl iodides, and (ii) any stereo- and regioisomers can, in principle, be prepared by simply changing the applying order of aryl iodides into the sequence.     

Use of Lewis Acids in Free Radical Reactions

The neglect of free radicals over the past few years has been overcome, and they are no longer only considered as interesting reactive intermediates with limited synthetic potential. New opportunities are opened up by performing radical reactions in the presence of Lewis acids. Rate enhancement of radical addition to olefins as well as stereochemical control of such reactions can be achieved in a unique manner. Recent examples of enantioselective radical reactions and perspectives for applications in catalysis are discussed.