褐煤是初具芳香结构基本单元、煤化程度最低的一种煤，因其具有较高的H/C原子比、挥发分以及镜质组含量而具有良好的液化性能。同时，因O/C原子比含量高，加氢反应过程中容易生成水，不利于原料煤中含氧官能团在直接液化过程中有效生产潜在高附加值含氧化合物。在供氢溶剂存在下，褐煤大分子结构单元含有多种含氧官能团，如酚类、醇类、羧基、醚类等，在热转化过程中表现出不同的反应行为。在氢自由基不足的情况下，裂解产生的苯氧自由基容易发生缩合反应;在氢自由基充足时可将苯氧自由基稳定至酚类，这些稳定后的酚类化合物在较高的温度下将发生脱羟基反应生成水。上述两个过程都在很大程度上降低了生成含氧有机化合物的可能性。以酚类化合物为主要目标产物为例，既要考虑对褐煤中含有酚羟基官能团在加氢转化过程中的保护，又要考虑醚键、醇类等官能团缩聚向酚类物质的转化。与此同时，探索产生水或CO_x的最小化工况，不仅有助于减少氢的消耗，也相应获得高附加值的有机含氧化合物。因此，探索煤中含氧官能团在供氢体系下加热过程中如何得到“保留”和“抑制缩聚”的机制是很有必要的。本文旨在分析褐煤中含氧官能团热加氢转化行为，围绕含氧芳香族化合物高值产品导向生产存在的问题，提出定向转化的研究思路，并针对褐煤本身特点提出其高值化利用路径合理建议。

Being a coal with the lowest degree of coalification,lignite is comprised of the basic aromatic structural u- nits. High H / C atom ratio,volatile content and vitrinite content of lignite favor the good liquefaction performance. On the other hand,high O / C atom ratio of lignite undesirably induces the generation of water during the hydrogenation, which is not conducive to the effective retention of potentially high value-added oxygen-containing compounds in the raw coal during the direct coal liquefaction. The direct liquefaction process of lignite in the presence of a hydrogen do- nor solvent leads to a series of reactions ( e. g. pyrolysis,hydrogenolysis,polycondensation and hydrogenation reac- tions). The macromolecular structural units of lignite contain a variety of oxygen-containing functional groups,such as phenolic,alcoholic,carboxylic,ether,etc. ,which exhibit the different chemical behaviors during the thermal transfor- mation process. Thermal cracking of oxygen radical fragments from the phenolic hydroxyl radicals in presence of the isufficient hydrogen radicals is inclined towards the crosslinking reactions. Also,these stable phenolic compounds unfa- vorably undergo the dehydroxylation at higher temperature that results in the formation of water. These two unsolicited processes heavily decrease the amount of oxygen contents which are expected to be present as phenolic compounds. This compels to explore the mechanism of retention and inhibition of polycondensation of oxygen-containing functional groups during the thermal transformation. However,contrary to this,at high temperature,the cleavage of aromatic ether bonds may become the valuable source of phenolic compounds. Therefore,for the investigation of the guided transfor- mation of phenolic compounds as the major target,it is essential to consider both the protection of the native phenols, and the trans-formation of ether bond and other functional groups into phenolic compounds. In this context,exploring the details about the minimization of hydrodeoxidation,which generates water or COx ,is beneficial to reduce the hydro- gen consumption and also to obtain the high value-added organic compounds containing oxygen functional groups. Suc- cinctly,it is presumed that this paper gives a sufficient information on the analysis of the transformation behavior of ox- ygen-containing organic compounds in lignite by the thermal hydrogenation. Through this review,the research ideas of guided transformation can be understood and the reasonable utilization pathways of high-value products on the basis of the characteristics of lignite are suggested.n