煤氧化产物的萃取分离

为实现对煤的高附加值利用,在温和条件下适度和选择性地氧化解聚煤,尽可能多地将其所含有机质转化为组成比较简单的有机化合物,并揭示氧化解聚反应机理,全面了解煤的组成结构特征、建立有效分离和分析反应混合物的科学方法。利用GC/MS对准东煤氧化解聚产物进行分析,发现煤的解聚产物非常复杂,氯代物、脂肪酸和芳香酸是煤氧化的典型物质。通过依次用七种不同极性溶剂对煤氧化所得水溶物进行萃取,实现了氧化产物族组分的初步分离。通过对产物的综合分析发现,主要产物有苯二甲酸、苯三甲酸、苯四甲酸、苯五甲酸、苯六甲酸。     

几种低阶煤的过氧化氢氧化解聚性能研究

在40℃利用5%H2O2水溶液分别对神府次烟煤(SF)、准东次烟煤(ZD)、胜利褐煤(SL)和先锋褐煤(XF)四种低阶煤进行了氧解,计算其氧解转化率和CO2生成率,结合元素分析、红外光谱以及酸性官能团测定结果比较了四种低阶煤的氧解性能以及其结构特征对氧化解聚性能的影响。结果表明,煤的氧化解聚与变质程度密切相关,变质程度越高,氧化反应性降低。另外煤的氧含量越高,特别是羧基以及酚羟基含量较高时,氧化解聚程度增大。     

几种低阶煤的过氧化氢氧化解聚性能研究

在40℃利用5％H2 O2水溶液分别对神府次烟煤（ SF）、准东次烟煤（ ZD）、胜利褐煤（ SL）和先锋褐煤（ XF）四种低阶煤进行了氧解,计算其氧解转化率和CO2生成率,结合元素分析、红外光谱以及酸性官能团测定结果比较了四种低阶煤的氧解性能以及其结构特征对氧化解聚性能的影响。结果表明,煤的氧化解聚与变质程度密切相关,变质程度越高,氧化反应性降低。另外煤的氧含量越高,特别是羧基以及酚羟基含量较高时,氧化解聚程度增大。     

木质素的催化加氢转化

木质素是来源于木质纤维素的一种重要的可再生生物质资源,可用于制备化学品和燃料。由于木质素本身结构的复杂性和稳定性使其难以有效利用。目前大量的制浆和造纸工业的木质素没有得到有效利用,大部分用于燃烧供能,并且造成了一定程度的环境污染。为了保护环境、实现可持续发展,催化转化木质素制备高附加值化学品成为了研究的热点。木质素转化的研究众多,但是进展依然相对缓慢。目前主要的转化方法包括碱催化解聚、酸催化解聚、热化学转化、加氢处理解聚、氧化解聚等。由于加氢处理解聚木质素可以获得低聚木质素、酚类等有价值的化学品和制备烃类燃料,是目前研究的热点和最有效的方法之一。但是,催化剂失活和解聚产物产率不高等依然是需要进一步解决的问题。基于此,梳理了近年来木质素加氢处理主要的催化体系和相关结果,提出了尚待解决的问题,以期为今后建立有效的木质素解聚体系并实现其高值化利用的相关研究提供参考。     

木质素的催化加氢转化

木质素是来源于木质纤维素的一种重要的可再生生物质资源,可用于制备化学品和燃料。由于木质素本身结构的复杂性和稳定性使其难以有效利用。目前大量的制浆和造纸工业的木质素没有得到有效利用,大部分用于燃烧供能,并且造成了一定程度的环境污染。为了保护环境、实现可持续发展,催化转化木质素制备高附加值化学品成为了研究的热点。木质素转化的研究众多,但是进展依然相对缓慢。目前主要的转化方法包括碱催化解聚、酸催化解聚、热化学转化、加氢处理解聚、氧化解聚等。由于加氢处理解聚木质素可以获得低聚木质素、酚类等有价值的化学品和制备烃类燃料,是目前研究的热点和最有效的方法之一。但是,催化剂失活和解聚产物产率不高等依然是需要进一步解决的问题。基于此,梳理了近年来木质素加氢处理主要的催化体系和相关结果,提出了尚待解决的问题,以期为今后建立有效的木质素解聚体系并实现其高值化利用的相关研究提供参考。     

木质素氧化解聚制备芳香醛研究进展

木质素作为自然界最丰富的芳香族化合物资源，通过可控的氧化解聚方式得到小分子芳香醛类化合物是实现木质素高附加值利用的重要途径。芳香醛作为重要的食用及日化香料、医药中间体、大宗化学品，目前主要通过石油化工产业链生产，以木质素生产芳香醛是具有重要研究意义和应用潜力的可再生资源利用途径。本文综述了国内外有关木质素制备芳香醛的最新研究进展，包括化学氧化解聚、电化学解聚、光催化解聚和生物催化解聚；对不同方法制备芳香醛的转化率和产率进行了对比，基于不同的解聚工艺与催化体系的特点进行评述与分析，展望未来木质素生产芳香醛的研究方向，以实现木质素的高值化利用。得出多方法耦合催化是可能进一步提高木质素生产芳香醛转化率与选择性的有效策略。     

由煤和页岩直接制取化学品的途径

由煤和页岩直接制取化学品的方法很多,其中主要的几种是:(1)深度氧化;(2)溶剂抽提;(3)加氢裂化;(4)循环干馏;(5)高温裂解。兹分述如下:一、深度氧化从最完全的利用煤的化学能的观点出发,氧化过程可以说是最有前途的方法。因为从氧化过程可以制取55～60%的重要化学品,而焦化过程最多也不超过3%。煤的氧化可以采用的氧化剂有硝酸、高锰酸钾、臭     

关于煤制芳香化合物的探讨

由煤制取高附加值芳香化学品是实现煤的清洁高效利用的有效途径,在对国内外相关研究现状分析的基础上,对煤的快速热解技术、煤热解物定向催化转化技术和煤加氢液化技术制取芳香化学品技术进行了探讨,提出了由煤制取高附加值芳香化学品的新思路。     

大兴煤的氧化产物红外和差热分析

对大兴煤先进行萃取再用双氧水将萃余煤进行氧化,并对其残余产物进行分析。热重结果显示煤有4次比较明显的质量减少,但第三次煤中不太稳定的大分子化合物发生分解、解聚导致失重最多。红外表明原煤的结构最复杂,而萃取和氧化使煤中的官能团种类变化很小但其中某些物质的含量却发生了较大的变化,从而导致大内部结构发生变化。     

煤有机化工产品—碳酸二甲酯

本文概述了由甲醇氧化羰基化合成碳酸二甲酯的催化体系及目前国外采用的生产工艺。简述了碳酸二甲酯及其所衍生的化学品的主要用途。结果表明:碳酸二甲酯应用范围十分广泛,是极有发展前途的煤有机化工产品。     

Physical mechanism of solvolytic liquefaction of coal through depolymerization: Factors leading to reduction in reagent concentration and reaction time

This Paper reports studies on the depolymerization reaction of Assam coal using p-toluenesulphonic acid (PTS) in phenol. Attempts have been made to determine the true extractability of coal by depolymerization by balancing the mineral matter present in the original coal with that in the residual depolymerized coal after extraction, and thus allow for the addition of phenol to the coal. The factors that could lead to a reduction in the amount of catalyst and reaction time required for depolymerization were studied. Three successive depolymerization reactions, followed by extractions in benzene/methanol (7:3 vol/vol), allowed the extraction of ≈50% coal with a coal:catalyst (PTS) ratio of 2:1. The particle size of the coal also affected the depolymerization reaction. Smaller coal particles (? 60 to + 120 BSS mesh, 250-125 gmm) resulted in a better extraction (60% in benzene/methanol (7:3 vol/vol)) compared with larger particles. The depolymerization reaction was found to be under diffusion and chemical control within the coal particle. Exposure of active sites in coal through extraction, increase in surface area through size reduction, chemical pretreatments, use of promoters and elevated temperatures should help to increase the rate of the depolymerization reaction.     

Coal liquefaction in lignin-derived liquids under low severity conditions

It is found that lignin-derived liquids when reacted with coal under mild reaction conditions (375 °C and 2.17 × 10⁶ − 3.55 × 10⁶ N m⁻¹) enhance the rate of coal depolymerization. Up to 30% enhancement in coal conversion rate is achieved using lignin-derived liquids. The influence of time of reaction and temperature on the degree of reaction was investigated. The lignin liquid-assisted coal depolymerization products (liquid) are observed to contain a significant amount of the desirable pentane-soluble fraction. Influence of the time of storage of lignin-derived liquids on coal conversion was also determined. Also reported are data on elemental analyses of the solid and liquid products. The liquid product analyses using n.m.r. and s.e.c. techniques are also presented. Based upon the experimental data collected, it is hypothesized that enhancement in coal depolymerization rate can be explained by a reaction pathway involving intermediates formed from lignin-derived lignin liquids. A mathematical model describing the reaction chemistry has been developed. Computed rate constants are also reported. The analysis indicates that the lignin-derived intermediates are short-lived as compared to the time needed for complete coal depolymerization.     

Internal rearrangement of hydrogen during heating of coals with phenol

Heating either Bruceton or Wyodak coal with phenol results in the thermal depolymerization of the coal yielding pyridine-soluble products and an insoluble residue. The depolymerization is accompanied by extensive rearrangements of hydrogen within the coals producing a soluble material enriched in hydrogen and a residue which is hydrogen poor. The hydrogen shuttle in Wyodak coal has a different temperature dependence than does the depolymerization, being favoured at higher temperatures. The $\text{H}\text{C}$ ratio of the soluble products increased with increasing conversion. Relatively small amounts (ca. 5%) of the products at high conversion are derived from phenol.     

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

The structure of lignin suggests that it can be a valuable source of chemicals, particularly phenolics. However, lignin depolymerization with selective bond cleavage is the major challenge for converting it into value‐added chemicals. Pyrolysis (thermolysis), gasification, hydrogenolysis, chemical oxidation, and hydrolysis under supercritical conditions are the major thermochemical methods studied with regard to lignin depolymerization. Pyrolytic oil and syngases are the primary products obtained from pyrolysis and gasification. A significant amount of char is also produced during pyrolysis. Thermal treatment in a hydrogen environment seems very promising for converting lignin to liquid fuel and chemicals like phenols, while oxidation can produce phenolic aldehydes. Reaction severity, solvents, and catalysts are the factors of prime importance that control yield and composition of the product.     

木质素催化解聚的研究进展

木质素是一种芳环结构来源丰富且价格低廉的可再生资源。从木质素出发催化解聚制备单酚类高附加值精细化学品和芳香烃烷烃等高品位生物燃料,可以部分替代以化石燃料为原料的生产过程,是生物质资源全组分高效综合利用的重要组成部分。在木质素催化解聚方法中,催化氢解可以直接将木质素转化为低氧含量的液体燃料,在生物燃料利用方面展现出巨大的潜力。本文详细总结了木质素的催化解聚方法,从催化剂类型、溶剂种类、反应机理及催化剂循环使用性等方面介绍了国内外的主要研究进展,着重阐述了木质素催化氢解方法。最后总结了当前木质素催化解聚过程中存在的难题,并对未来的技术发展提出了建议和展望。     

Depolymerization of oxidized bituminous coals

Certain high-sulphur-containing, high-volatile bituminous (hvb) coals have been converted into products which are almost completely soluble in chloroform. These products were obtained by a series of reactions involving initial oxidation with 2N nitric acid, depolymerization with boron trifluoride-phenol, and acetylation. Solubility of the depolymerized coal decreased sharply when the nitric acid reaction was eliminated or was replaced with a hydrochloric acid treatment. The extent of oxidation by the nitric acid treatment is discussed. Also included in this investigation are a low-sulphur-containing hvb coal and a low-volatile bituminous coal. After depolymerization, the solubilities of these two coals in chloroform were comparatively low.     

Enhancement of benzene-methanol extraction (low molecular weight products) of coal in depolymerization reactions

Depolymerization of coals is an important reaction for the study of coal structure. Coal is depolymerized by using p-toluenesulphonic acid in phenol. Depolymerization takes place mainly through the cleavage of C-C and C = bonds and subsequent phenolation, whereas C-O-C linkages of coal are not affected by this treatment. In the present work, reactions, such as, reduction of coal through Li in ethylene-diamine, alkaline-degradation and dry HCl gas, which are known to cleave C-O-C linkages in coal selectively, have been coupled (as a pre-treatment) with depolymerization reactions. This could enhance the yields of low molecular weight products from coal as revealed by the enhancement in the benzene-methanol (7/3 vol/vol) extractability of depolymerized coals. The use of Ce(IV) salt, benzoyl peroxide, lead tetra-acetate and potassium persulphate, promotes the depolymerization reaction to low molecular weight products. These studies help in understanding the mechanism of generation of asphaltenes and, thereby, might help in the studies of liquefaction of coal.     

Depolymerization of Turkish lignites. 2. Effect of phenol concentration in a closed system

A lignite (C, 66.9 wt%) was depolymerized, using sulphuric acid as a catalyst, in a closed system in which the phenol/coal ratio was varied from 1.5 to 10. The products were separated by solvent extraction and silica gel chromatography. The i.r. and n.m.r. spectra, and the molecular weight of the products were measured. In the experiments with a phenol/coal ration of 10, complete depolymerization of the coal was seen provided the temperature of depolymerization was at least 210 °C. The products generally contained disubstituted aromatic structures connected by methylene bridges, it was found that as the phenol/coal ratio was increased there was a decrease in the number of methylene bridges connecting the aromatic structures. The molecular weights of the straight-chain pentane and benzene-soluble material were lower than the molecular weights of similar fractions in depolymerization experiments carried out in open systems. A method for the structural analysis of straight-chain pentane and benzene-soluble material based on i.r., ¹H n.m.r. and molecular weight measurements is suggested.     

基于CPD模型的低阶煤催化解聚过程模拟分析

低阶煤催化解聚过程定量分析和放大需要合理描述该过程的宏观动力学模型,使用化学渗透脱挥发分（CPD）模型结合陕西长焰煤的催化解聚实验,对低阶煤催化解聚过程进行了定量分析。综合对催化剂作用机理的认识,结合催化解聚实验结果确定相应表观动力学参数,所得模拟结果与实验结果趋势一致、吻合良好,其较好地体现了不同热解过程差异,低温下催化解聚产物释放量较少,温度升高后产物量才会高于原煤热解。模型中催化剂对焦油产率的影响体现在复合速率常数、交联反应活化能上,随两者增大,焦油产率均增加;Fe基催化剂有助于促进侧链断裂,提高气体产率,Zn基催化剂可抑制交联反应,但交联反应活化能较大时,受热解温度限制,焦油量增加变缓。     

Depolymerization of coals in hot pyridine or phenol

Experimental evidence is presented that suggests cleavage of bonds by solvent attack is a possible contributing mechanism for coal depolymerization.