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

08-06-06 Chapter 1 Coal as an Organic Sediment Review: Guide to 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 coal 　　3 Coal-forming processes（成煤过程，成煤作用） Summary 2. Precursors of coal Lignins （木质素） Carbohydrates （碳水化合物） Proteins （蛋白质） Lipoids （类脂） : Oils, fats, and waxes B. Carbohydrates 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 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 forms but usually as a food reserve. 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 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 of the order of several thousand. 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, but a general range o