煤化学 英语课件 chapter 1 coal as an organic sediment - a copy

1、Chapter 1 Coal as an Organic Sediment,Review:,Coal is a kind of sedimentary organic rock Coal had originated from ancient plant remains. Very complicatedly biochemical and physicochemical actions had worked in coal-forming process. Coal-formation had proceeded under certain climatic, biological, env

2、ironmental and geological conditions.,A definition of Coal Coal is a kind of sedimentary organic rock originating from ancient plant remains undergone complicatedly biochemical and physicochemical changes under certain climatic, biological, environmental and geological conditions.,08-06-06,2,Guide t

3、o new lecture,Prelude questions to Coal as an Organic Sediment Which plant remains could have been converted into coal? And what precursors had been experienced before coal had been formed ? How is the processes like from the origins to coal? Contents 1 Origins of coal 2 Precursors (先驱，前体，母体) of coa

4、l 3 Coal-forming processes（成煤过程，成煤作用）,08-06-06,3,1. The origins of coal,A brief description (please rehearse this paragraph) Coal was formed from partially decomposed (已降解的，已腐烂的）(and subsequently (后来，随后） metamorphosed (变质，变形）) plant debris (碎片，残骸） which collected in regions where waterlogged (浸满水的，涝

5、的） or swampy (沼泽的，湿地的） conditions prevailed (流行，盛行，占优势）. These conditions prevented complete decay (腐烂，降解） of the debris as it accumulated and eventually (最后的） led to the material now as coal.,08-06-06,4,In general terms, the debris consisted of trees, ferns（蕨类植物）, rushes （灯芯草，灌木）, lycopods （石松属植物）,

6、 and several thousand plant species that have been identified in coal beds, but it appears that none of the species identified in many different coals originated in brackish-water （盐水） locales （区域）. Similar types of plant remains may be found in all types (ranks （煤阶）) of coal， but, of course, the re

7、lative amounts （相对含量） vary considerably （相当地，非常地）. On this basis （由此）, it is not surprising that coal differs markedly （显著地） in composition from one particular seam are not uncommon, due not only to the wide variety of plant debris that could have formed the precursors （母体，前体） but also to the many d

8、ifferent chemical reactions that can occur during the maturation （成熟） process.,By the eyes of coal chemistry: plants-higher and lower plants. the lower : unicellular （单细胞的） or multicellular （多细胞的） fungoids （菌类） and algaes （藻类） without distinction （区分，分化） of roots, stems and leaves the higher : liche

9、ns （苔藓）, ferns （蕨类）, gymnosperm （裸子植物） and angiosperm （被子植物）, etc, and there is distinction of roots, stems and leaves,08-06-06,5,Thus, once plant debris has accumulated under the “correct” conditions, the formation of peat（泥炭） gradually occurs （发生，出现）. Peat is not actually classified as coal but it

10、 is, nevertheless （仍然，不过）, believed to be that material which is formed as the initial step in the process. However, to become coal, peat must progress （前进，进展，经历） through what is loosely termed “coalification” （煤化作用） process.,The coalification process is, in essence （本质）, the progressive （渐进的，累进的） c

11、hange in the plant debris as it becomes transformed from peat to lignite （褐煤） and then through the higher ranks （高阶） of coal （such as subbituminous （次烟煤） and bituminous （烟煤） coals） to anthracite （无烟煤）. The degree of coalification generally determines the rank of the coal, but the process is not a se

12、ries of straightforward （简单的，直截了当的） chemical changes. For example, the metamorphism （变质作用） of the plant debris not only relies on （depend on） geological time （地质年代） but also on temperature and pressure.,08-06-06,6,Thus, when the organic debris (which may be identified as peat) is buried beneath （在 之

13、下） overburden （过载，重压）, various physicochemical （物理化学的） processes occur as part of the metamorphosis （变质，变形）. The major influences are believed to be the resulting （由此引起的） heat and pressure developed because of the overlying （上面堆垛的） sedimentary cover (overburden).,This leads to changes in the constit

14、uents （成分，组成） of the debris such as an increase in the carbon content, alteration （改变） of the functional groups （官能团）, alteration of the various molecular structures ultimately （finally） resulting in the loss of water , oxygen, and hydrogen with the increased resistance （阻力，阻抗，电阻） to solvents, heat,

15、 and oxidation.,08-06-06,7,All theories about the formation of coal require that the original plant debris eliminate （去除，减少，消除） oxygen and hydrogen continuously under the prevailing （优势的） conditions, ultimately leading to a product containing approximately （大约） 90% w/w carbon, i. e., anthracite （无烟煤

16、）. In order for the maturation （成熟） to proceed, chemical principles （原理，法则） require that oxidation reactions be completely inhibited （禁止）.,However, in the early stages （早期阶段） of calcification, microorganisms （微生物） may play an important role and, somewhat paradoxically （看似矛盾而实际地）, they may interact w

17、ith the plant material under aerobic （需氧的） conditions as well as under anaerobic （厌氧的） conditions.,The formation of coal under the slow conditions generally referred to （指的是） as geological time （地质时期） may , nevertheless （不过，仍然）, be regarded as （被认为是） occurring in the absence of （缺少 的） oxygen, thereb

18、y （因此） promoting （促进，提高，提升） the formation of highly carbonaceous （碳质的，高碳的） molecules through losses of oxygen and hydrogen from the original organic molecules.,08-06-06,8,9,08-06-06,Summary,Plant remains,2. Precursors of coal,Lignins （木质素） Carbohydrates （碳水化合物） Proteins （蛋白质） Lipoids （类脂） : Oils, fa

19、ts, and waxes,The constituents （组成，组分） of the organic portion of the original plants, which ultimately （最终，最后） transformed （转化） into coal, has great influence on （对 有极大影响） the finished coal structure and its composition. So it is necessary to make complete understanding of the constituents of the or

20、ganic portion of plants.,The makeup of the organic portion of plants consists of carbohydrates, lignin, proteins and lipoids.,Note that each of these compound types is a very broad classification, indicating the general complexity （复杂性） of the original plant debris. It is this fact alone which deter

21、mines the complexity of the “finished coal molecules”.,08-06-06,10,The relative amount （相对量） of these constituents vary greatly with the particular species of plant as well as the relative stage of growth （生长阶段）. Nevertheless （不过）, it is possible (in an attempt to simplify （使简化） an already complex （

22、复杂的） situation) to acknowledge （承认，答谢） some generalities （共性，一般性）; the lignin content of plants may fall within （在之间） the range 10-35% w/w while in woody material the lignin may be within the narrower range of 25-30% w/w range. Thus, from these broad generalities alone, the original plant debris (de

23、pending on location and the circumstances leading to the deposition （沉积）) is, indeed, increasing in complexity （复杂性）.,08-06-06,11,Lignin （木质素） and cellulose （纤维素） are considered to be the major organic precursors （母体） to coal although there is little evidence （证据） to support （赞成，支持，证明） this theory.

24、Nevertheless, laboratory （实验室） investigations （研究） into the nature of the transformation （变化，转化） have been carried out （实施，进行） for many years and perhaps a brief discussion is warranted （保证，授权，有理由） here not only to indicate the complexity of the problem but also to show the speculation （思考） involved

25、 in （涉及） this concept （概念）. Indeed, the concept of a coal structure has continued for several decades （十年） and it is questionable （有争议的，可疑的） as to whether or even if there is a need to define coal in terms of （根据，按照） a distinct （clear） molecular structure.,08-06-06,12,A. Lignin,Lignin（木质素） has been

26、considered one of the most important substances involved in the transformation of plant constituents（成分） into coal, and the molecular structure of lignin remains largely unknown and speculative （费解的）. A Lignin is regarded as a polymer 。,08-06-06,13,Aromatic polymers （芳香族聚合物）,Monomeric units: aromati

27、c alcohols （单体的单位）,Simplified representation of part of the lignin structure,(I) coniferyl alcohol （针叶树的） (II) sinapyl alcohol （芥子醇） (III)p-coumaryl alcohol （香豆醇）,These are the monomeric (单体) units found in lignin. Lignin is regarded as a polymer (or mixed polymer) of any one (or more) of these alco

28、hols.,08-06-06,14,Thus, the carbon-carbon linkages are of the diphenyl type (I) as are a variety of aliphatic （脂肪族的） carbon-carbon linkages between the aromatic rings (II). In addition, the molecule of lignin contains various ether linkages (III; IV, and V;).,The chemical structure of lignin is stil

29、l largely speculative, but it has been possible to make some general deductions (推论) about the nature of the linkage in this complex natural product.,Furthermore (此外，而且), investigations with lignin from conifers (松类，针叶树) have shown that diphenyl-type linkages (联苯型桥键) account for (占) approximately (a

30、bout) 25% of carbon-carbon linkages. The remainder (其余，剩余) are connected by means of ether (醚) bonds. Thus, while (虽然) data of this type do not illustrate (阐明) the molecular structure of a complex molecule such as lignin, they do illustrate the bonds which either may remain intact(完整的) or may be rup

31、tured (破裂，打破) during the maturation process.,08-06-06,15,Table 1-1 Methoxyl（甲氧基） and nitrogen contents (wt. %) of lignins from various sources,The extent of the amount of each particular alcohol has been presumed (推测) to be recognizable (可知的) from determinations (测试) of the methoxyl (-OCH3) content

32、of various lignins，but the complication (复杂化) of nitrogen in the lignin is also evident .,This latter problem has not been fully resolved (解决) and therefore it is not known whether the nitrogen is inherent (内在的) in the lignin (i.e., chemically combined and part of the lignin substance) or whether th

33、e nitrogen arises (出现) by virtue of (由于) the presence (存在) of nitrogen-containing molecules that are difficult to separate from the lignin.,08-06-06,16,Lignin（木质素） is the main substances in cell wall of the higher plants, and has been considered one of the most important precursors involved in the t

34、ransformation of plant constituents（成分） into coal, and the molecular structure of lignin still remains largely unknown and speculative （费解的）.,08-06-06,17,18,08-06-06,B. Carbohydrates,Sugars（糖）,Saccharides （糖）,Monosaccharides（单糖）,Polysaccharides（多糖）,Carbohydrates （碳水化合物）,Disaccharides （二糖）,Tetrasacch

35、arides （四糖）,Trisaccharides （三糖）,Pentasaccharides （戊糖）,Celluloses （纤维素）,Starches （淀粉）,Carbohydrate，namely saccharide or sugar, is quite a broad type of constituents of plant, and was believed to have made a lot of contribution to coal formation.,Carbon Oxygen Hydrogen,The monosaccharides(单糖), are the

36、 building blocks(构造单元) of the more complex carbohydrates. They are actually polyhydric(多羟基的) alcohols(醇) containing five to eight carbon atoms, and the five-and six-carbon sugars are the most common.,Table Structure and occurrence of the common five- and six-carbon atom sugars in plants,Their simple

37、 formulas indicate that they contain a carbonyl(羰基) (aldehyde(醛) or ketone(酮) function(官能), but this is not the actual case. The carbonyl functions usually occur in combination with (与 一起)one of the hydroxyl functions (in the same molecule) to form a cyclic(成环的，环状的) hemiacetal(半缩醛) or a hemiketal(半酮

38、缩醇),08-06-06,19,Although the monosaccharides (单糖) do occur as such in nature, it is more common to find the sugars occurring naturally in pairs (disaccharides(二糖) or in threes (trisaccharides(三糖) and , more likely, as the high molecular weight polysaccharides(多糖) It is the polysaccharides which most

39、 probably contribute to(贡献于) the source material(原始材料/物质) of coal, especially as the two well-known polysaccharides cellulose(纤维素) and starch(淀粉). The fibrous tissue in the cell wall of plants and trees contains cellulose and starch，and starch also occurs throughout the plant kingdom in various form

40、s but usually as a food reserve.,08-06-06,20,The chemical composition of starch varies with the source but in any one starch there are two structurally different polysaccharides. Both usually consist entirely of glucose(葡萄糖) units but one is a linear(线型的) structure（amylose(直链淀粉)）whereas the other is

41、 a branched structure (amylopectin(支链淀粉)，. Thus, in contrast to(相对于) the somewhat speculative chemistry of lignin, the structural chemistry of the polysaccharides （多糖） (cellulose and starch) is generally more well defined. For example, the molecular formula of cellulose is (C6H10O5)n, where n may be

42、 of the order of several thousand.,08-06-06,21,Fig. 1-6 Simplified structures for cellulose (I) and starch (II).,08-06-06,22,23,08-06-06,1-7 A three-dimensional representation of the carbon skeleton of cellulose,Fig. 1-8 A three-dimensional representation of the carbon skeleton of starch (amylose),F

43、ig. 1-9 A three-dimensional representation of the carbon skeleton of branched starch (amylopectin),08-06-06,24,C. Proteins,Proteins are those nitrogen-containing organic substances which occur in the protoplasm of all plant and animal cells. The element composition of proteins varies with the source

44、, but a general range of protein composition is usually of the order:,With other elements, e.g., phosphorous (nucleoproteins) and iron (hemoglobin) also being present in trace amounts in certain proteins.,08-06-06,25,The characteristic structural feature of proteins is a chain, or a ring, of amino a

45、cids(氨基酸) joined together by amide linkages .,Simplified representation of part of a protein (peptide) chain of alanine,But the distinction between a protein and a peptide is not always clear. One arbitrary choice is to use a molecular weight of 10000 as a distinction between the two classes. That i

46、s: proteins have a molecular weight in excess of 10000 while peptides below this value.,Amido group,Carboxyl group,The naturally occurring peptides have relatively short, flexible chains and, although hydrated in aqueous solution, can be reversibly dehydrated. On the other hand, proteins have very l

47、ong chains which have definite conformational character with water molecules filling the interstices.,Amino acids,Peptides,Proteins,08-06-06,26,Proteins occur throughout nature in a wide variety of sizes and shapes and many proteins contain metals such as iron, zinc, and copper which, in turn, are i

48、ntimately involved in the physiological (biological) functions of the molecules to which they are bound. They are believed to be the main contributors of the organic nitrogen-containing comounds.,08-06-06,27,Fig. 1-11 Schematic representation of protein structure with indications of (a) atomic and (

49、spatial arrangement of the helix.,08-06-06,28,Table 1-4 Some commonly occurring proteins,08-06-06,29,D. Lipoids,脂类化合物是指不溶于水而溶于醚、苯、氯仿等有机溶剂的有机化合物。在植物中脂类化合物主要有以下几种。 脂肪：属于长链脂肪酸的甘油酯。高等植物中含量少(1-2%)，低等植物含量高(20%左右)。在生化作用下在酸性或碱性溶液中分解生成脂肪酸和甘油，参与成煤作用。 蜡质：主要是长链脂肪酸与含有2426个碳原子的高级一元醇形成的脂类，化学性质稳定，不易受细菌分解。 树脂: 树脂是植物

50、生长过程中的分泌物，当植物受伤时，胶状的树脂不断分泌出来保护伤口。针状植物含树脂较多，低等植物不含树脂。树脂不溶于有机酸，不易氧化，微生物也不能破坏它，因此能很好地保存在煤中。 角质和木栓质、孢粉质：化学性质十分稳定，不溶于有机酸，微生物也难以作用，在成煤过程中能保存下来。,All the organic constituents in plants, which not soluble in the organic solvents such as ethers, benzene, chloroform, etc., fall within lipoid. They are: Oils an

51、d fats; Waxes; Resins; Cutins, Seberins, sporins.,08-06-06,30,Carbohydrates （碳水化合物） Lignins （木质素） Proteins （蛋白质） Lipoids （类脂） : Oils, fats, and waxes,Precursors of coal,包括纤维素、半纤维素及果胶质。 纤维素：在泥炭沼泽的酸性介质中，纤维素可以分解为纤维二糖和葡萄糖等简单化合物。半纤维素：比纤维素更易分解或水解为糖类和酸。果胶质为糖的衍生物，呈果冻状。在生物化学作用下，水解成一系列单糖和糖醛酸,木质素也是植物细胞壁的主要成分，在

52、泥炭沼泽中，在水和微生物作用下发生分解，与其他化合物共同作用生成腐植酸类物质，这些物质最终转化成为煤。所以木质素是植物转变为煤的原始物质中最重要的有机组分。,蛋白质：高等植物中蛋白质含量少；低等植物中蛋白质含量高。在泥炭沼泽和湖泊的水中，蛋白质分解成氨基酸、喹啉等含氮化合物，参与成煤作用，但对煤的性质没有决定性的影响。是煤中硫、氮元素的来源之一。,脂类化合物是指不溶于水而溶于醚、苯、氯仿等有机溶剂的有机化合物。化学性质稳定，在成煤过程中能保存下来。,08-06-06,31,. Coal formatting process,Question: what is the coal forming

53、process like?,08-06-06,32,Coal-forming process peatification coalification The rank, type and grade of coal,Contents,08-06-06,33,key terms and expressions,Diagenetic 成岩的 Geophysical 地球物理的 Geochemical 地球化学的 tectonic 地质的，构造的 coal seam/strata 煤层 Coalbed gas 煤层气 depositional environment 沉积环境 temperature

54、, time, and forces grade of coal 煤级 type of coal 煤的类型 rank of coal 煤阶,the range of impurities included,Acording to the coal-forming vegetation,the degree of metamorphism or coalification,Coal formation 成煤作用 Coal forming process 成煤作用 Peatification 泥炭化作用 Saprofication 腐泥化作用 Coalification 煤化作用 metamorp

55、hism 变质作用 Peat 泥炭 Lignite，brown coal 褐煤 subbituminous coal 次烟煤 bituminous coal 烟煤 Anthracite 无烟煤 Hard coal 硬煤 Soft coal 软煤 stone-like coal 石煤,08-06-06,34,1. Coal forming process,The complicated and far-lasting way had been undergone over millions and millions of years from ancient plant remains, whi

56、ch is called coal-forming process today. The process is also called coal-formation and is often expressed as followed:,Higher Plants lower plants,Peat sapropel,Peatification,Lignite sapropelic coal,Bituminous coal,Anthracite stone-like coal,Diagenisis or lignification,metamorphism,coalification,Bitu

57、minization,anthracization,saprofication,Diagenisis or lignification,coalification,从远古植物遗体到煤，经历了复杂且慢长的历程，这个历程就是今天所说的成煤过程，也称为成煤作用（过程），常用下图来表述：,08-06-06,35,36,08-06-06,Plant remains,peat,Peatification,lignite,Bituminous coal,Anthracite,Diagenisis or lignification,metamorphism,coalification,Coal forming

58、 process,Bituminization,anthracization,Including two stages: peatification and coalification.,高等植物死亡后，在生物化学作用下，变成泥炭的过程称为泥炭化作用。 在这一阶段，植物首先在微生物作用下，分解和水解为分子量较小的性质活泼的化合物，然后小分子化合物之间相互作用，进一步合成新的较稳定的有机化合物，如腐植酸、沥青质等。植物经泥炭化作用成为泥炭，在两方面发生巨大变化： （1）组织器官（如皮、叶、茎、根等）基本消失，细胞结构遭到不同程度的破坏，变成颗粒细小、含水量极大、呈胶泥状的膏状体泥炭； （2）组成

59、成分发生了很大的变化，如植物中大量存在的纤维素和木质素在泥炭中显著减少，蛋白质消失，而植物中不存在的腐植酸却大量增加，并成为泥炭的最主要的成分之一，通常达到40%以上。,Three processes: the microbiological degradation of the initial plant material, the conversion of the lignin of the plants into humic substances, and the condensation of these humic substances into larger coal molecules The kind of original plants, conditions of decay, depositional environment, and movements of the Earths crust are important factors in determining the nature, quality, and rela