循环供氢溶剂在神华煤直接液化工艺中的应用

在神华煤直接液化工艺中,为达到理想的反应深度,煤直接液化反应需要供氢性能良好的循环供氢溶剂、氢气、煤粉及催化剂等原料。其中,经过预加氢处理后的循环溶剂,具有良好的供氢性能,使得煤直接液化反应条件温和。在煤直接液化过程中,溶剂起着溶解煤粒、溶胀分散、稳定自由基、提供和传递转移活性氢、稀释液化产物等作用。当前,提高循环供氢溶剂自身的供氢和传递氢能力是煤直接液化新技术开发的重点之一。     

煤直接液化溶剂研究进展

分析了煤加氢液化的反应机理,发现溶剂在加氢液化过程中起着非常重要的作用。重点讨论了溶剂在反应过程中的热溶解作用以及供氢和传递氢作用,介绍了目前煤直接液化工业生产中溶剂的常用分类,最后指出开发新型溶剂,对缓和煤加氢液化条件和改善生产工艺具有重要意义。     

洗油对五彩湾高惰质组煤直接液化性能的影响

以洗油为供氢溶剂,考察了溶煤比、反应温度和氢初压对新疆五彩湾煤样加氢液化性能的影响.结果表明,在煤液化中,洗油部分加氢,生成具有强供氢能力的物质,增强其供氢能力,可以作液化溶剂,且溶煤比由四氢萘为溶剂的3降低到1.75;虽然氢初压为8.0 MPa,但反应终压为16.3 MPa,与四氢萘为溶剂时相当;油产率达到59.24％,转化率达到81.05％.     

煤直接液化中溶剂的作用和种类

讨论了煤液化中溶剂的作用和种类,煤液化中溶剂的作用为溶解溶胀作用,稀释分散粒以及对煤热裂解生成的自由基的保护作用。并着重讨论了供氢溶剂的供氢作用和转移氢作用。溶剂的各类分为工业和研究中常用的普通混合溶剂,煤焦油,石油渣油等重质油溶剂和废塑料、废橡胶等废化学品溶剂,初步分析了它们的供氢作用和传递转移活性氢作用。     

氢气在煤高温快速液化中的作用

首先利用实验室建立的一套平衡液相取样法实验装置测定了氢气在四氢萘和萘中的溶解规律,其次通过间歇式微型反应釜研究了氢气在煤高温快速液化中的作用。结果表明:①氢气在溶剂中的溶解度随温度与压力的增加而增加;在一定的温度与压力下,氢气在四氢萘和萘中的溶解度在5 min内达到最大溶解量的78.54%左右,之后溶解度开始逐步缓慢上升直到30 min时达到最大溶解量;②在充足的四氢萘作为溶剂的液化反应中,氢气对于煤高温快速液化反应几乎没有影响,活性氢主要来源于溶剂;在萘作为溶剂的液化反应中,钼酸铵催化剂促进了氢气参与反应,但是总转化率的变化较小,仅仅促进了沥青烯向油方向的转化。③压力对于煤高温快速液化中四氢萘的供氢性能有影响。     

植物纤维原料液化新技术

介绍了植物纤维原料液化的几种新技术。植物纤维在微波作用下可以有效地液化,反应时间也显著缩短,即使是结晶度较高的纤维素也可充分降解;固体酸催化剂有较高的催化活性和选择性,而且可以循环利用;离子液体能使液化反应在近似均相的反应体系中进行,能高效地溶解纤维素、木质素和半纤维素,提高液化效率。超临界流体具有高扩散性和低表面张力,能够很好地渗透到固体内部,是植物纤维原料液化的优异溶剂。     

煤液化油中低级酚生成的影响因素研究

为了探究反应温度、反应压力、催化剂添加量以及供氢溶剂对褐煤直接液化油中低级酚生成的影响以及低级酚生成的机理,利用模型化合物邻苄基苯酚在煤直接液化条件下进行加氢反应。实验结果表明:邻苄基苯酚在液化条件下主要发生桥键断裂反应生成低级酚,苯环不易被加氢饱和。温度升高对促进邻苄基苯酚桥键断裂有利;压力升高则不利于其桥键断裂;铁系催化剂添加量的增加会促进桥键断裂;供氢溶剂四氢萘相比十氢萘会抑制低级酚的生成。邻苄基苯酚加氢液化的产物以苯酚与甲苯为主,邻甲酚与苯相对较少。     

煤直接液化循环溶剂加氢稳定试验研究

在300 m L加氢试验装置上进行加氢稳定试验,考察了反应压力对煤直接液化循环溶剂性质的影响,并通过0.5 L高压釜煤液化试验,考察了煤在不同加氢深度循环溶剂中的液化效果。结果表明,随着溶剂加氢反应压力的升高,循环溶剂密度、黏度及氮含量递减,氢碳原子比及供氢指数递增,循环溶剂性质得到改善,供氢性能得到提高,从而促进煤的转化率和油收率提高。当加氢反应压力由12.5 MPa升至19.3 MPa时,煤的转化率从87.21%提高到88.40%,液化油收率从51.62%提高到55.58%。     

煤高温快速液化过程中的单原子与双原子氢转移机理

氢转移对煤的加氢液化至关重要,理解氢转移机理对于改善煤液化过程具有重要意义。在微型反应釜中通过考察氢气的溶解、溶剂类型以及不同类型催化剂对煤高温快速液化的影响,揭示了煤高温快速液化过程中单原子氢和双原子氢的转移机理。结果表明,在以四氢萘、氢气为条件的高温快速液化过程中,主要的活性氢来源于溶剂所提供的单原子;在以四氢萘、氮气为条件的高温快速液化过程中,不同催化剂对溶剂提供单原子氢的影响不同。在以四氢萘和萘、氢气为条件的高温快速液化过程中,双原子氢基本未参与液化反应,溶解并不是其参与液化反应的主要影响因素。以萘为溶剂、氢气气氛下的高温快速液化过程中,双原子氢参与反应需要一定的时间。在以萘或四氢萘、氢气为条件的高温快速液化过程中通过加入一定量的催化剂,可以促使双原子氢快速参与反应。     

煤液化油的性质与化学组成

煤液化可以分成两个重要步骤,第一步是煤结构单元中连接部分的热分解,并接着反应碎片被供氢溶剂所稳定;第二步是所谓沥青烯结构的加氢裂解。因此,煤液化油的收率和性质在很大程度上取决于反应条件、催化剂和进料煤。本文简要地综述了几个正在开发过程(SRC-Ⅰ,SRC-Ⅱ,EDS,H-Coal和Synthoil)的煤液     

木材液化及其在高分子材料中的应用

木材通过液化可转化为具有反应活性的液态产物,进一步反应可以制备胶粘剂、聚氨酯材料等新型高分子材料。文章从方法、机理以及其产物在制备高分子材料等方面对木材液化的研究进展进行了评述。     

植物纤维组分在聚氨酯中的应用

植物纤维原料及其组分可部分替代多元醇用于聚氨酯的制备中,其中的纤维素、木质素及其衍生物均可在其中作为多元醇组分或者填料。这种多元醇组分既可由纤维素、半纤维素或木质素直接充当,也可以通过液化手段制得。植物生物质基多元醇与异氰酸酯反应可制成聚氨酯;植物纤维原料及其组分作为填料时,可以改善聚氨酯的热稳定性及机械性能。文章综述了植物纤维以及植物纤维组分在聚氨酯中的应用,介绍了液化过程中植物纤维原料、液化试剂、催化剂等的使用方法。     

煤直接液化残渣改性沥青的可行性研究

介绍了道路沥青的组成、性质和评价指标,以及煤直接液化残渣的来源和组成特性。简单介绍了煤直接液化残渣制备改性沥青的工艺,对国内的研究现状进行总结及分析,总结前人研究成果,并指出煤直接液化残渣作为沥青改性剂在实验研究中是可行的,但能否适用于工业化应用还需要开展更加深入的研究性工作。     

Studies on the Mechanism of Formation of the Products of Liquefaction of Cellulose and Aspen Poplar Wood

Abstract

Studies are reported on the chemical nature and mechanism of formation of the components of the oil fraction obtained by the alkali-catalyzed liquefaction of aspen poplar wood and separately of cellulose. Along with the smaller molecular weight compounds reported earlier (5) evidence has been obtained for the presence of polymeric fractions involving ether linkages and which show a bimodal pattern of molecular weights. Using appropriate model substances, some evidence ha3 been obtained for the production and involvement of one- and two-carbon fragments as well as ketene-type intermediates in the liquefaction process. Examination of the role of pH during the conversion process suggests that the initially alkaline medium is required to degrade the cellulose to smaller fragments, including possible saccharinic acids, with a corresponding decrease in pH. Then at an appropriate pH (now acidic) and temperature the resulting degradation products are converted to components of the final oil.     

木质纤维原料的热化学液化

用热化学方法 ,可以将木质纤维原料液化成为烃、醇、酚、羧酸等多种有机物以及一些无机物。在所有的木质纤维原料液化手段中 ,热化学液化是最容易实现、同时又最经济的方法。综述了木质纤维原料热化学液化反应机理及实现木质纤维原料液化的工艺进展。将木质纤维原料转化成液体燃料或化工原料 ,对充分利用自然界中可再生资源 ,降低燃烧石油造成的环境污染 ,具有重要的意义     

Regulation of radicals by hydrogen-donor solvent in direct coal liquefaction

Radicals are important intermediates in direct coal liquefaction. Certain radicals can cause the cleavage of chemical bonds. At high temperatures, radical fragments can be produced by the splitting of large organic molecules, which can break strong chemical bonds through the induction pyrolysis of radicals. The reaction between the formation and annihilation of coal radical fragments and the effect of hydrogen-donor solvents on the radical fragments are discussed in lignite hydrogenolysis. Using the hydroxyl and ether bonds as indicators, the effects of different radicals on the cleavage of chemical bond were investigated employing density functional theory calculations and lignite hydrogenolysis experiments. Results showed that the adjustment of the coal radical fragments could be made by the addition of hydrogen-donor solvents. Results showed that the transition from coal radical fragment to H radical leads to the variation of product distribution. The synergistic mechanism of hydrogen supply and hydrogenolysis of hydrogen-donor solvent was proposed.     

未经化学改性的木材液化研究进展

木材是固态的天然高分子材料,通过液化可将其转化为具有反应活性的液态分子,该技术对充分利用自然界中可再生资源具有重要的意义。综述了未经化学改性的木材液化的研究进展,并对木材液化技术存在的问题以及木材液化的发展趋势进行简要分析。     

Chemistry of solvents in coal liquefaction: Quantification of transferable hydrogen in coal-derived solvents

Hydrogen was evolved as hydrogen sulphide when coal-derived solvents for liquefaction were heated with sulphur (dehydrogenation method) and their naphthene contents were quantified by titration and ¹³C n.m.r. analysis to estimate the amount of transferable hydrogen from hydroaromatics present in the solvent. Examination of synthetic solvents consisting of model compounds confirmed the validity of both approaches. The content of transferable hydrogen, thus measured, in the various solvents correlated well with their liquefaction activities using Morwell brown coal. This suggests that the sufficient stabilization of radical fragments derived thermally from the coal at the initial stage of its liquefaction leads to high conversion. It was also shown that the dehydrogenation method was applicable to non-distillable heavy fractions of coal-derived liquids such as SRC which are difficult to measure by n.m.r. because of their limited solubility.     

The roles of vehicle and gaseous hydrogen during short contact time coal liquefaction

The roles of the vehicle and gaseous hydrogen during short contact time liquefaction (SCTL) in microreactors were examined by using a number of synthetic vehicles. The importance of vehicles during SCTL was evaluated on their ability to convert coal to tetrahydrofuran (THF)-soluble products. Reaction conditions were three minutes at 425 °C following a one minute heat-up. Although the consumption of hydrogen (hydrogen donor or gaseous hydrogen) by reactive coal fragments is minimal during the early stages of liquefaction (as in SCTL reactions), hydrogen donors were important and could be ranked according to the extent of conversion to THF-soluble products (tetrahydroquinoline > hydrogenated pyrene > dihydroanthracene = dihydrophenanthrene > tetralin). The importance of gaseous hydrogen was also studied. Gaseous hydrogen was needed if either quality or quantity of hydrogen donor was not adequate in a SCTL reaction. With certain synthetic vehicles, the SCTL stage of an integrated two-stage liquefaction process could be conducted in the absence of hydrogen. Solubility properties that might enhance solubilization of coal-derived products, and therefore the extent of liquefaction, were examined by varying the concentration of certain components (m-cresol and quinoline) of the synthetic vehicle mixtures. Solubility effects were minimal.