艾丁褐煤直接液化产物中酚类形成影响因素研究

Study on influencing factors of phenols formation in direct liquefaction of Aiding lignite

针对艾丁褐煤高氧含量的特征,通过高压釜对艾丁褐煤直接加氢液化进行试验研究,考察了反应温度、催化剂添加量、氢气初压和溶剂含量对艾丁褐煤液化产物酚类物质生成的影响。结果表明,艾丁褐煤直接液化生成酚类物质的最适宜条件为:反应温度430℃,催化剂添加量1%,氢气初压5.0 MPa,溶剂含量50%。各低级酚在总酚中的占比分别为:苯酚0.39%,邻甲酚0.51%,间甲酚1.08%,对甲酚0.97%,二甲酚5.07%。通过碱抽提煤液化油得到的酚类物质中的低级酚(苯酚+C1phenol+C2 phenol)在总酚中占比10.7%,低级酚主要集中在保留时间为24~33 min,高级酚占比较大,且随保留时间的延长既多又杂;提高反应温度、溶剂含量和催化剂添加量有利于提升总酚产率,促进煤反应生成酚类物质,氢气初压对总酚产率影响不大;提高反应温度和催化剂添加量能提升低级酚在总酚中的占比,使高级酚趋向于反应生成低级酚,提高溶剂含量和氢气初压抑制低级酚在总酚中的占比。煤直接液化工艺流程中,通过加氢反应,在低温分离过程中尽可能达到较高的酚产率,同时通过将高分进行循环,以延长高分的反应时间,提高油产率,即实行分级加氢液化将有利于控制和提高油和酚产率。

According to the characteristics of high oxygen content of Aiding lignite,the hydrogenation liquefaction of Aiding lignite were investigated in the autoclave.The effects of reaction temperature,amount of catalyst loading,H 2 initial pressure and solvent content on the formation of phenols in direct liquefaction products of Aiding lignite were investigated.The results show that the optimum conditions for the direct liquefaction of Aiding lignite to produce phenolic compounds are listed as follow:reaction temperature 430℃,catalyst addition 1%,hydrogen initial pressure 5.0 MPa,solvent content 50%.The proportion of low-boiling phenol in total phenol is 0.39% phenol,0.51%o-cresol,1.08% m-cresol,0.97% p-cresol and 5.07% xylenol,respectively.The lower phenol(phenol+C1 phenol+C2 phenol)accounts for 10.7% of the total phenol by alkaline extraction of coal liquefaction oil,and the retention time of low-boiling phenol is 24-33 minutes,high phenol accounts for a large proportion,which is both abundant and complex with the extension of retention time.The increase of reaction temperature,catalyst content,and solvent content can promote the total phenol yield and the reaction of coal to produce phenolic compounds,while the hydrogen initial pressure has little effect on the total phenol yield.The increase of reaction temperature and catalyst content promotes the proportion of low-boiling phenol in total phenol,which makes the high-boiling phenol tend to produce low-boiling phenol,while the solvent content and initial pressure of hydrogen inhibit the proportion of low-boiling.In the process of direct coal liquefaction,high phenol yield can be achieved in the process of low temperature separation through hydrogenation reaction.And through circulation of high fraction,the reaction time of high fraction is prolonged and the oil yield can be increased,that is to say,it will be beneficial to control and increase the yield of oil and phenol by the graded hydroliquefaction.