磁性负载型超强碱的构筑及其在中低阶煤催化加氢裂解中的应用

Middle- and low-rank coals mainly include subbituminous coals and lignites. Selectively cleaving oxygen-containing bridged bonds in organic matter of the coals is crucially important for the coal directional depolymerization and subsequent efficient utilization. In this project, our main investigations are: (1) to prepare magnetic powders using chemical coprecipitation method and incorporate the powders with proper adhesive and template, coat the comlex powders with a proper silica-containing material; (2) to wash out the template with ammoniumnitrate/ethanol solution for making mesopores in the support; (3) to sequentially impregnate two strongly alkalinous inorganic active components into the mesopores to finally prepare magnetic supported superbase (MSSB); (4) to understand microstructure and adsorption properties of the MSSB using multiple advanced instruments; (5) to examine the MSSB-catalyzed hydrocracking of model compounds, in which oxygen-containing bridged bonds (OCBBs) are contained between aromatic rings, to reveal the mechanisms for the MSSB-catalyzed cleavage of the OCBBs; (6) to successively destroy different OCBBs in the coals by sequential hydrocracking over the MSSB at lower temperatures to 300 oC to comprehensively and deeply understand the OCBB types and the structures of aromatic rings which are connected by the OCBBs by subsequent analyses; (7) to examine the recoverability of MSSB and change in the activity of MSSB for catalytic hydrocracking during repeated use. These investigations will provide important scientific basis for the coal directional conversions.

在温和条件下选择性地切断中低阶煤有机质中的含氧桥键对于中低阶煤的定向解聚和后续的高效利用至关重要。本项目利用化学共沉淀法制备磁性粉体，进而选用适当的粘合剂和模板剂与粉体复合并用适宜的含硅原料包覆，用硝酸铵的乙醇溶液从复合后的粉体中洗涤出模板剂使载体富含介孔，在微波辐射下依次浸渍两种强碱性的无机活性组分于介孔中使之原位反应从而形成磁性负载型超强碱（MSSB）；借助多种先进的手段了解MSSB的微观结构和吸附性能等；以芳环间具有含氧桥键的化合物作为模型化合物，考察MSSB催化的模型化合物的加氢裂解，了解MSSB催化含氧桥键断裂的机理；用MSSB由低温到300oC依次催化中低阶煤的加氢裂解，逐级破坏中低阶煤中的含氧桥键，通过后续的分析了解中低阶煤中含氧桥键的类型和所连接的芳环的结构；考察MSSB的可回收性和循环使用过程中催化加氢裂解活性的变化。基于上述研究为中低阶煤定向转化提供重要依。

中低阶煤富含芳环（特别是缩合芳环）和含氧桥键。在温和条件下，有效切断连接芳环的含氧桥键对于中低阶煤的高效利用至关重要。.本项目利用浸渍和原位分解的方法制备了高活性的磁性双功能固体超强碱Ni-Mg2Si/AP，重点考察了二苄醚（DBE）和二苯醚（DPE）及新疆皮里青次烟煤的两种萃余物，即超声辐射萃取所得萃余煤（R1）和常规萃取所得萃余煤（R2），在Ni-Mg2Si/AP存在下的加氢裂解和加氢反应。.研究结果表明：在150 oC下，Ni-Mg2Si/AP和加压氢气存在下，DBE和DPE均能够被完全转化；在初始氢压（IHP）3 MPa和240 oC下反应2 h，DBE被全部转化为甲基环己烷，而在同样的IHP和温度下反应4 h，DPE被完全转化为环己烷。在240 oC和3 MPa的IHP下，R1催化加氢转化（CHC）所得可溶物的收率为36.4%，远高于R1非催化加氢转化（NCHC）所得可溶物（SP）的收率（1.8%）。R1的NCHC所得SP的主要成分是芳酚（占45.5%），其次是芳烃，而R1的CHC所得SP的主要成分是芳烃（占68.2%），其次是链烷烃和氢化芳烃。R2的NCHC所得SP的主要成分是非取代芳烃（占28.0%），其次为烷基取代的菲和少量的醚及含氮有机化合物，而R2的CHC所得SP中主要成分为非取代的环烷烃，收率高达66.8%，其中环己烷的相对含量为65.3%，其次是链烷烃及少量的烷基取代的环己烷、四氢萘和烷基取代的四氢萘。从分子水平上提出了两种模型化合物及R1和R2的CHC的路径和H-与H…H协同转移的机理。.本项目所制备的Ni-Mg2Si/AP是一种同时具备加氢裂解和加氢的双功能高活性催化剂，可以有效地切断连接芳环的含氧桥键、脱除杂原子并使芳环饱和加氢。