西部地区富油煤资源丰富，煤热解是实现其高效低碳化清洁利用的重要途径。但传统的煤热解技术存在焦油产率低、品质差和煤气热值低等问题。深化催化热解基础研究是突破上述技术瓶颈的关键。为此，本文聚焦煤热解催化剂的设计策略创新与催化剂构效关系这一核心科学问题，以提高煤催化热解催化剂回收性能及提高焦油产率和品质为出发点，设计制备了系列磁性催化剂MgFe₂O₄、SiO₂@MgFe₂O₄、HZSM-5@SiO₂@MgFe₂O₄(HSMF)、Mo/MgFe₂O₄和Mo/HSMF。并且，以补连塔煤（BLcoal）为富油煤样，系统研究磁性催化剂结构、性质，以及回收再生次数等对富油煤催化热解产物分布及品质的影响。研究结果对于富油煤催化热解关键技术应用开发有一定理论指导价值，同时，对富油煤清洁低碳化高效利用有一定现实意义。主要研究结果如下：

(1) 通过溶胶凝胶法合成了磁性能稳定的MgFe₂O₄。采用溶胶凝胶法，结合XRD和VSM分析，研究了焙烧温度和升温速率对MgFe₂O₄结构和磁性的影响规律。结果表明，焙烧温度700℃，升温速率25℃/min条件下，所合成的MgFe₂O₄结构及磁性能较好，其达到了181.5 emu/g，经5次循环热处理后，MgFe₂O₄的结构和回收率无明显变化。

(2) 以MgFe₂O₄为核合成了具有核壳结构的磁性催化剂SiO₂@MgFe₂O₄和HSMF。采用Stober法和原位生长法制备了SiO₂@MgFe₂O₄和HSMF，通过XRD、SEM、N₂低温吸脱附和VSM等方法对核壳磁性催化剂结构和磁性能进行了表征。结果表明，SiO₂@MgFe₂O₄和HSMF具有核壳结构，HSMF比表面积与HZSM-5比表面积相近；与纯MgFe₂O₄相比，经SiO₂隔离包覆后，SiO₂@MgFe₂O₄饱和磁化强度下降了10.7 %， 进一步经HZSM-5载体层包覆后，HSMF饱和磁化强度总体下了29.3 %，其饱和磁化强度仍能达到128.2 emu/g。因此，包覆改性是影响MgFe₂O₄磁性关键因素。

(3) 以MgFe₂O₄和HSMF为载体，采用等体积浸渍法合成了负载体型Mo/MgFe₂O₄和Mo/HSMF催化剂。通过XRD、N₂低温吸脱附和VSM等方法对核壳磁性催化剂结构和磁性能进行了表征。结果表明，由于金属氧化物的负载量小于10%，在XRD中未发现属于Mo的特征峰。与未负载金属的磁性催化剂相比，Mo/MgFe₂O₄的比表面积增加了373.7%，孔径减少了43.9%，Mo/HSMF的比表面积减少了13.8%，孔径减少了2.6%，这表明活性钼氧化物已成功负载到了磁性载体上，Mo/MgFe₂O₄和Mo/HSMF催化剂饱和磁化强度仅分别降低了0.6%和1.7%。

(4) 磁性催化剂可以有效的提高热解产物中焦油的产率及品质。在固定床反应器上，以BLcoal煤为研究样品，对所上述系列磁性催化剂进行了催化热解性能表征。研究了磁性催化剂组成、结构和磁性对热解产物分布的影响规律。结果表明，在氢气气氛下，催化剂的活性总体优于氮气气氛，且磁性催化剂的活性大小表现为Mo/HSMF＞HSMF＞Mo/MgFe₂O₄＞MgFe₂O₄＞SiO₂@MgFe₂O₄；在氢气气氛下，焦油收率最高达到15.08 %,比原煤提高了5.87%。GC-MS分析表明，与无催化剂相比，在磁性催化剂上，煤催化热解产生的焦油中，稠环芳烃含量减少，脂肪烃含量增加。不同磁性催化剂上，脂肪烃含量增加的顺序为HSMF＞MgFe₂O₄＞SiO₂@MgFe₂O₄。因此，在磁性催化剂存在下，BLcoal煤热解可实现焦油产率和品质的同步提高。

(5) 回收磁性催化剂经再生后仍保持较好的催化活性。采用磁选方法，从热解半焦产物中回收磁性催化剂，采用800℃焙烧1h处理进行回收催化剂的再生，结合XRD、N₂低温吸脱附和VSM等分析，研究了催化剂再生与循环使用次数对其结构和催化活性的影响规律。结果表明，磁选法可从催化热解半焦中高效分离回收磁性催化剂，但积炭较为严重；经再生后，再生磁性催化剂回收率最低值仍高出加入量的0.51%，其中Mo/MgFe₂O₄经三次循环再生后，回收率仍可达到98%。这表明磁性催化剂积炭量较大。与新鲜催化剂相比，在氢气气氛下，催化剂磁性下降程度高于氮气气氛，饱和磁化强度下降程度顺序为：1R-MgFe₂O₄＞1R-SiO₂@MgFe₂O₄＞1R-HSMF。这表明磁性核壳结构设计有利于保护磁核MgFe₂O₄免受热解反应的影响。BLcoal在再生磁性催化剂上热解产物分布和规律与新鲜磁性催化剂相近，但半焦产率增加，焦油收率略有下降。其中在三次再生后Mo/MgFe₂O₄催化剂上，热解焦油的产率仍可达到11.7%。

The western region is abundant in oil-rich coal resources, and coal pyrolysis plays a paramount role in realizing the efficient utilization of low-carbon clean. The western region is abundant in oil-rich coal resources, and coal pyrolysis is an important way to realize its high-efficiency, low-carbon and cleaning utilization. However, the traditional coal pyrolysis technology has the problems of low tar yield, poor quality and low calorific value of coal gas. Deepening the basic research of catalytic pyrolysis is the key to break the above technical bottlenecks. Therefore, this paper has focused on the core scientific issues of the design innovation of coal pyrolysis catalysts and the structure-activity relationship of the catalysts. With the starting point of improving the recovery performance of coal catalytic pyrolysis catalysts and improving the yield and quality of tar, a series of magnetic catalysts has been designed and prepared, such as HZSM-5@SiO₂@MgFe₂O₄(HSMF), Mo/HSMF,MgFe₂O₄,SiO₂@MgFe₂O₄ and Mo/MgFe₂O₄. In addition, BLcoal was used as an oil-rich coal sample, and the structure, properties of magnetic catalysts, as well as the number of recycling and regeneration times , have been systematically studied on the distribution and quality of products from the catalytic pyrolysis of oil-rich coal. The research results have a certain theoretical guiding value for the application and development of the key technology for the catalytic pyrolysis of oil-rich coal, which have a certain practical significance for the cleaning, low-carbon and efficient utilization of oil-rich coal. The main research results were as follows:

(1) MgFe₂O₄ with stable magnetic properties was synthesized by sol-gel method. The effects of calcination temperature and heating rate on the structure and magnetic properties of MgFe₂O₄ were studied by sol-gel method combined with XRD and VSM analysis. The results show the structure and magnetic properties of MgFe₂O₄ have the best performance when the calcination temperature is 700℃ with the heating rate of 25℃/min, which reaches 181.5 emu/g. After five cycles of heat treatment, the structure and recovery rate of MgFe₂O₄ have no significant change.

(2) The magnetic catalysts SiO₂@MgFe₂O₄ and HSMF with core-shell structure were synthesized with MgFe₂O₄ as the core. SiO₂@MgFe₂O₄ and HSMF were prepared by Stober and in-situ growth method. The structure and magnetic properties of the core-shell magnetic catalyst were characterized by XRD, SEM, N₂ low temperature adsorption-desorption, and VSM. The results show that SiO₂@MgFe₂O₄ and HSMF have a core-shell structure, and the specific surface area of HSMF is similar to that of HZSM-5. Compared with pristine MgFe₂O₄, the saturation magnetization of SiO₂@MgFe₂O₄ is decreased 10.7% after coating with SiO₂. And after further coating with HZSM-5, the saturation magnetization of HSMF decreased 29.3%, even so its saturation magnetization can still reach 128.2 emu/g. Therefore, coating modification is a key factor affecting the magnetic properties of MgFe₂O₄.

(3) Mo/MgFe₂O₄ and Mo/HSMF catalysts were synthesized by the equal volume impregnation method with MgFe₂O₄ and HSMF as carriers. The structure and magnetic properties of the core-shell magnetic catalyst were characterized by XRD, N₂ low temperature adsorption-desorption, and VSM. The results show that no characteristic signals belong to Mo are found in XRD, since the loading of metal oxides is less than 10%. Compared with the magnetic catalyst without metal supporting, the specific surface area of Mo/MgFe₂O₄ and Mo/HSMF increased 373.7%and13.8%, meanwhile the pore diameter decreased 43.9% and 2.6% respectively, which indicated that the active molybdenum oxide was loaded onto the magnetic carrier successfully. The saturation magnetization of Mo/MgFe₂O₄ and Mo/HSMF catalysts decreased 0.6% and 1.7%, respectively.

(4) Magnetic catalyst can effectively improve the yield and quality of tar in pyrolysis products. The above series of magnetic catalysts were characterized in a fixed bed reactor with BLcoal as the research sample. The effects of composition, structure and magnetism of magnetic catalysts on the distribution of pyrolysis products were investgated. The results show that the activity of the catalyst in hydrogen atmosphere is better than that in nitrogen atmosphere, and the activity of the magnetic catalyst is Mo/HSMF> HSMF > Mo/MgFe₂O₄ > MgFe₂O₄ > SiO₂@MgFe₂O₄. GC-MS analysis showed that the content of polycyclic aromatic hydrocarbons decreased and the content of aliphatic hydrocarbons increased in the tar produced of coal catalytic pyrolysis on magnetic catalyst compared with that without catalyst. On different magnetic catalysts, the increasing order of aliphatic hydrocarbon content is HSMF>MgFe2O₄>SiO₂@MgFe₂O₄. Therefore, in the presence of magnetic catalyst, the yield and quality of tar can be improved simultaneously.

(5) The magnetic catalyst remained positive catalytic activity after recycle experiments. Magnetic catalyst was recovered from pyrolysis semi coke by magnetic separation. The catalyst was calcined at 800 ℃ for 1 h for regeneration. The effects of regeneration and recycling times on the structure and catalytic activity of the catalyst were studied by XRD, N₂ adsorption-desorption and VSM. The results show that magnetic separation can effectively separate and recover magnetic catalyst from catalytic pyrolysis semi coke, but carbon deposition is serious; after regeneration, the lowest recovery of regenerated magnetic catalyst is still higher than 0.51% of the added amount, and the recovery of Mo/MgFe₂O₄ can still reach 98% after three cycles of regeneration. This indicates that the amount of carbon deposited on the magnetic catalyst is abundant. Compared with the fresh catalyst, the decrease degree of magnetic properties of the catalyst in hydrogen atmosphere is higher than that in nitrogen atmosphere, and the order of saturation magnetization decrease degree is: 1R-MgFe₂O₄>1R-SiO₂@MgFe₂O₄>1R-HSMF. This indicates that the design of magnetic core-shell structure is beneficial to protect the magnetic core MgFe₂O₄ from pyrolysis reaction. The distribution and regularity of pyrolysis products of BLcoal on the regenerated magnetic catalyst is similar to that of the fresh magnetic catalyst, but the yield of semi-coke increases and the yield of tar decreases slightly. Among them, on the Mo/MgFe₂O₄ catalyst after three regenerations, the yield of pyrolysis tar can still reach 11.7%.

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