低阶煤溶剂热解序列特征及含氧结构组分分级加氢转化机理的研究

Low-rank coals are regarded as an abundant reserve in China, and low-rank coal liquefaction is a feasible way to reduce the external dependence of crude oil. The thermal decomposition temperature range is quite wide due to the complexity of coal structure, and coal pyrolysis in the direct liquefaction temperature range shows unique sequence characteristics. The pyrolysis of different components have different requirements for catalysis and hydrogen supply environment, and the differences bring difficulties for the optimization of high oxygen-containing coal liquefaction in traditional processes. In light of the technical problems of high oxygen-containing coal liquefaction, a grading liquefaction technology was proposed to solve the problems of high hydrogen consumption and high energy consumption caused by the high oxygen and water contents of coal. This new technology can give full play to the advantageous of different catalysts in their appropriate reaction conditions, therefore improve the oil yield and conversion of coal liquefaction. The main research contents are as follows: the pyrolytic sequence characteristics of low-rank coal in organic solvents, the grading conversion mechanism of oxygen-containing structure in low-rank coal, the effect of staged conversion of oxygen-containing structure with high–stability on the hydroliquefaction of low-rank coal. This study can provide scientific basis and basic data for the development of direct liquefaction technology of high oxygen-containing coal, which has important theoretical significance and application value.

我国低阶煤资源丰富，利用其液化制油是减少原油对外依存度现实可行的途径。煤因结构组成的复杂性造成热分解温度范围相当宽，在直接液化温度范围内的热解反应呈现特有的序列特征，而不同组分结构的热解反应对催化及供氢环境等有着不同的需求，这种需求上的差异给高含氧煤采用传统液化工艺的优化运行带来了工艺不协调甚至冲突。针对高含氧煤液化技术难题提出分级复合催化液化新工艺技术，解决了原料高含氧含水引起的高氢耗和高耗能等问题，同时充分发挥不同催化剂在各自适宜反应条件下的优势，提高煤直接液化的转化率及油收率。主要研究内容包括：低阶煤在有机溶剂中的热解序列特征；低阶煤含氧结构组分的分级转化反应机理；高稳定性含氧结构组分分级深度转化对低阶煤加氢液化率的影响。本项研究可为高含氧煤直接液化新技术的开发提供科学依据和基础数据，具有重要的理论意义和应用价值。

我国低阶煤资源丰富，利用其液化制油是减少原油对外依存度现实可行的途径。煤因结构复杂性在直接液化温度范围内的热解反应呈现特有的序列特征，而不同组分结构的热解反应对催化及供氢环境等有着不同的需求，这种需求上的差异给高含氧煤采用传统液化工艺的优化运行带来了工艺不协调甚至冲突。本项目以低阶煤为原料，构建适合低阶煤直接液化的分段多级加氢液化催化体系。全面考察褐煤在供氢溶剂中的热解序列特征，探讨了供氢溶剂下褐煤含氧结构断裂与褐煤液化转化关系；考察碱催化剂在褐煤液化过程中的催化作用并构建褐煤分段多级催化加氢液化反应过程，开展了煤温和液化性能以及煤与重油共加氢反应特性的探索研究，构建了煤与重油共加氢反应动力学模型。研究发现，在温和条件下添加γ-FeOOH和γ-Fe2O3可以提高红柳林煤液化转化率和油产率，添加α-Fe能显著降低沥青质产率，提高液化油产率。褐煤液化转化与含氧结构的断裂显著相关。在H2/THN体系中，相对较低的液化温度下(330~380℃)，单独添加NC催化剂能明显提高锡林浩特褐煤的液化性能，且催化效果显著优于单独添加FO催化剂；NC催化条件下，N2/THN系统中褐煤液化转化率和油产率均显著高于H2/1-MN系统。两段升温液化反应过程可以减少液化气体产率和水产率，同时降低氢耗，但沥青质产率较高。添加NC或NCFO后两段升温褐煤液化转化率和油产率均高于单段升温液化。根据煤与重油共加氢反应过程中产物产率和煤转化率随时间的变化关系，建立了三组分恒温反应动力学模型，易反应部分反应生成油气和沥青质所需表观活化能分别为113.33kJ/mol和98.17kJ/mol，难反应部分反应生成沥青质所需表观活化能为28.74kJ/mol，沥青质反应生成油气所需表观活化能为88.31kJ/mol。本项目围绕煤加氢液化过程中与转化效率高相关性的含氧结构组分开展分级加氢转化机理的研究，为进一步研究高含氧煤多级催化液化体系提供了技术支撑。