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Liquid Fuels and Chemical Feedstocks

机译：液体燃料和化学原料

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Coal can react directly with hydrogen to cleave C-C bonds and remove heteroatoms (O, N and S), which is referred to as "direct liquefaction". Such processes are catalyzed and involve more than one stage and generate distillates in high yield. Alternatively, coal can be gasified with steam into a mixture of carbon monoxide and hydrogen, known as synthesis gas or "syngas", which then can be converted with suitable catalysts into a wide variety of fuels and chemical feedstocks by what is commonly referred to as Fischer-Tropsch or FT synthesis. This route is known as "indirect liquefaction", which is mature in the sense that commercial plants are currently operating using this process, notably the SASOL process in South Africa. This contrasts with direct liquefaction where, despite the intensive process development that has occurred with a number of demonstration plants being operated, high capital costs and current low oil prices have prevented commercial plants coming into operation using this process, with the exception of the Shenhua plant in China. Despite the uncertain outlook, a major development programme since the 1970s, triggered by rapid increases in oil prices, has led to the severity of the process conditions being reduced considerably and a much greater understanding of the underlying chemistry has been gained, which provides the main focus for this overview. The impact of coal structure, solvent composition and catalysis on the conversion of coal to liquids is described, together with the chemical nature of the heavy intermediates and final distillate products.
机译：煤可以与氢直接反应以裂解C-C键并除去杂原子（O，N和S），这被称为“直接液化”。这样的过程被催化并且涉及一个以上的阶段，并且以高收率产生馏出物。或者，可以用蒸汽将煤气化成一氧化碳和氢气的混合物，称为合成气或“合成气”，然后可以用合适的催化剂将其转化为多种燃料和化学原料，通常称为费-托合成法。该路线被称为“间接液化”，从商业工厂目前正在使用该工艺（特别是南非的SASOL工艺）运行的意义上说，它已经成熟。这与直接液化形成鲜明对比，尽管许多示范工厂都在进行密集的工艺开发，但高资本成本和当前的低油价却阻止了商业工厂使用该工艺运行，神华工厂除外在中国。尽管前景不明朗，但自1970年代以来，由于石油价格的迅速上涨而触发了一项重大开发计划，该计划导致工艺条件的严重性大大降低，并且对基本化学方法有了更深入的了解，这为本概述的重点。描述了煤的结构，溶剂组成和催化对煤转化为液体的影响，以及重质中间体和最终馏出产物的化学性质。

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