【作者】 李莉；

【导师】 宗志敏；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2023， 博士

【摘要】 新疆中低阶煤储量丰富,但因其高灰分和低热值导致新疆中低阶煤被用作燃料先天不足。另一方面,富含芳环和含氧桥键有利于转化新疆中低阶煤为高值化学品。了解新疆中低阶煤的分子组成结构特征和定向转化机理对于开发中低阶煤的非燃料利用技术至关重要。为了实现温和条件下新疆中低阶煤中有机物的定向解聚,高收率地获得组成简单的可溶物,本论文设计了金属-酸性载体复合材料（Ni/Si O₂和Ni/ZTMS）、固体超强酸（TFMSA/CNOFW）和固体碱（NiM/Al₂O₃）作为催化剂。以几种煤相关模型化合物为探针,考察了催化剂的加氢转化活性和在催化加氢转化（CHC）过程中活性氢的生成和转移机理。以新疆地区的润北褐煤（A）和沙尔湖次烟煤（B）作为研究对象,选用等体积的二硫化碳/丙酮混合溶剂（IMCDSAMS）分别萃取了A和B,得到萃取物（EP,分别为EP_A和EP_B）和萃余物（ER,分别为ER_A和ER_B）。考察了EP的催化加氢精制、ER的催化加氢裂解和催化加氢醇解相关的反应机理,得到如下研究成果:（1）A和B的常温超声辐射萃取与Ni/Si O₂催化的EP_A和EP_B的催化加氢精制在常温和超声辐射下用IMCDSAMS萃取A和B,EP_A和EP_B的收率分别为16.5%和11.8%。用扫描电镜（SEM）观察的结果表明,EP呈不规则的片状堆叠,而ER表面较原煤更加光滑。用气相色谱/质谱联用仪（GC/MS）从EP_A和EP_B中检测出一系列烷基取代芳烃和含氧有机化合物,相对含量（RC）分别为45.5%和64.7%。用Ni/Si O₂在220 ^oC和4 MPa的初始氢压（IHP）下对EP_A和EP_B进行催化加氢精制分别得到催化加氢后的EP_A和EP_B（CHEP_A和CHEP_B）。用GC/MS从CHEP_A和CHEP_B中仅检测到链烷烃和环烷烃,其中环烷烃是重要的液体化学品。分别考察了Ni/Si O₂催化的4-肉桂苯酚和均三苯基苯的加氢转化,根据对所得反应混合物的分析,提出Ni/Si O₂先将H₂活化为H…H,H…H在Si O₂上异裂为游离的活性H⁺和固定在Si O₂表面的H^-,H…H和H⁺的协同作用促进了芳环的加氢和杂原子的脱除。经过4次循环后Ni/Si O₂仍具有良好的催化加氢活性且可在500^oC下H₂还原4 h后恢复原来的催化活性。（2）ER_A和ER_B的催化加氢裂解通过热解制备了焙烧的镍-有机骨架（CNOFW）,在常温下浸渍三氟甲磺酸（TFMSA）于CNOFW制备了磁性固体酸TFMSA/CNOFW。该催化剂可有效活化H₂和乙醇,具有优异的加氢裂解活性。与非催化反应相比,TFMSA/CNOFW催化的ER_A和ER_B的加氢裂解所得正己烷可溶物（HSP_A和HSP_B）的收率显著提高（分别由16.9%和14.1%提高至47.3%和35.8%）,且在所得可溶物中检测到大量的芳烃和含氧化合物而没有任何环烷烃,表明该催化剂有效促进了ER_A和ER_B催中桥链的裂解而非芳环的加氢。TFMSA/CNOFW的强酸性有利于异裂H₂获得游离的H⁺,H⁺转移到ER_A和ER_B中桥链上的氧原子或由桥链连接的芳环的取代位导致桥链的断裂。HSP_A和HSP_B的组成较为简单,有利于通过后续的分离获得有机化合物纯品。在乙醇体系中,TFMSA/CNOFW催化的ER_A和ER_B所得乙醇可溶物（ESP_A和ESP_B）的收率分别高达51.5%和42.9%。根据GC/MS分析,ESP_A和ESP_B中的含氧有机化合物主要为酚类和乙酯类化合物,表明ER_A和ER_B在催化乙醇解过程中发生了>CH-CH<键或>C_alk-O-键的裂解。催化乙醇解残渣(R_A-E和R_B-E)表面形貌分别呈小孔和清晰的叶脉状结构。R_A-E和R_B-E表面的含氮物种分别以吡咯氮和吡啶氮为主。这些富含杂原子的衍生物是制备N,O-自掺杂的煤基多孔碳材料的良好前驱体。（3）ER_A和ER_B的两阶段催化解聚催化剂Ni/ZTMS是将活性组分Ni负载到以粉煤灰为原料合成的类沸石分子筛（ZTMS）上制备而成的。Ni/ZTMS具有优异的>C-O-键裂解活性。在240 ^oC和4 MPa的IHP下,Ni/ZTMS催化2-苯基苯酚转化为联环己烷的选择性高达97.7%。在ER_A和ER_B催化转化的一阶段中,Ni/ZTMS催化ER_A和ER_B加氢转化所得可溶组分(SP_1-A和SP_1-B)中环烷烃的RC分别为31.9%和64.8%,表明在Ni/ZTMS的作用下,ER_A和ER_B发生了>C_alk-O桥键的裂解、芳环的加氢和杂原子的脱除反应。Ni/ZTMS通过Ni纳米颗粒（NNPs）和强Lewis酸性位点协同活化H₂为活性H…H,继而异裂H…H为游离的H⁺和固定在载体表面的H^-。H…H和H⁺分别在促进芳环的加氢和杂原子脱除上起关键作用。磁性的Ni/ZTMS可通过外加磁场迅速回收和循环使用。在ER_A和ER_B的催化解聚的第二阶段中,TFMSA/CNOFW催化ER_A和ER_B加氢裂解所得可溶组分(SP_2-A和SP_2-B)中以链烷烃和芳烃为主,表明>C_ar-C_alk/>C_alk-C_alk桥键的裂解是该阶段的主导反应。对两阶段产物综合评估,一阶段富含环烷烃和脱氢芳烃的可溶组分有潜力精制为环烷基液体化学品,而富含芳烃和含氧化合物的二阶段可溶组分可通过后续的分离获取平台化学品。（4）ER_A和ER_B的催化醇解以层状氢氧化物为前驱体制备了双金属层状介孔材料NiRu/Al₂O₃。NiRu_2%/Al₂O₃的形貌是由大量薄纳米片堆叠而成的绣球花状,Ni和Ru均匀分散在层状纳米片表面。在异丙醇体系中,NiRu_2%/Al₂O₃在180 ^oC和2 MPa的初始氮压（INP）下催化ODN完全转化且萘与四氢萘的RC之和高达84.9%,这是活性氢物种H…H、H.和H^-共同作用的结果。NiRu_2%/Al₂O₃催化ER_A加氢裂解所得可溶物（ISP_A）的收率（60.4%）远高于非催化可溶物(ISP_A-N)的收率（36.7%）。根据GC/MS分析,ISP_A-N中含氧化合物的RC高达96.2%,其中89.2%为酚类化合物。而ISP_A中检测到大量的芳烃和环烷烃,表明碱性NiRu_2%/Al₂O₃可促进H^-和H…H的生成和转移,它们不仅高效裂解>CH-O-桥键还可促进酚类化合物中氧原子的原位脱除及芳烃的芳环加氢。在甲醇体系中,NiRu_2%/Al₂O₃催化BOB裂解的产物主要是甲苯和苯酚,推测甲醇重整生成的H.是主要的活性氢物种,它促进了BOB中>C_alk-O-的裂解。NiRu_2%/Al₂O₃催化ER_A和ER_B甲醇解的可溶组分经乙醚萃取后,富集了大量的甲基酚类化合物,它们是重要的平台化学品。（5）ER_A和ER_B的催化裂解和催化加氢通过原位共沉淀法制备了介孔材料NiM/Al₂O₃（M=Zn、Mg或Ca）。呈中强碱性的Ni Ca/Al₂O₃的催化活性最高,可在低IHP（1 MPa）下促进以>CH-O-为主的多种桥键的加氢裂解而非氢化芳环。以Ni Ca/Al₂O₃作催化剂,在180 ^oC和1 MPa的IHP下二苄醚完全转化为甲苯。相应地,在Ni Ca/Al₂O₃催化的ER_A和ER_B加氢裂解所得可溶物中仅检测到以正构烷烃为主的链烷烃和以萘及其同系物为主的1-4环芳烃,没有检测到任何环烷烃或含杂原子的有机化合物。链烷烃来源于ER_A和ER_B中烷氧基芳烃中与芳环相连的>C-O-键的裂解,芳烃则来源于>C-O-桥键的裂解和/或酚类化合物的脱羟基。Ni Ca/Al₂O₃的中强碱性有利于异裂H₂获得游离的H^-,H^-转移到ER_A和ER_B中与氧原子相邻的碳原子上导致>C-O-键的断裂。由于所得可溶物的组成简单,通过后续的分离易于获得芳烃纯品。在高的IHP（5 MPa）下,Ni Ca/Al₂O₃表现出优异的芳环加氢活性,在180 ^oC和5 MPa的IHP下催化9-菲酚加氢转化为全氢菲的选择性高达95.6%。在相同条件下,Ni Ca/Al₂O₃催化的ER_A和ER_B的加氢转化所得可溶物中除链烷烃外,仅检测到以非取代环烷烃和烷基取代的环己烷为主的环烷烃类化合物,其中联环己烷在SP_A-2中的RC高达22.3%。更多还原

【Abstract】 Middle-and low-rank coals are abundant in Xinjiang,while the characteristics of high ash and low calorific value lead to its inherent inadequacy for the utilization as fuel.On the other hand,aromatic rings and oxygen-containing bridge bonds are rich in the structure of middle-and low-rank coals,which can be considered as excellent precursors for value-added chemicals.Understanding the structural characteristics of molecular composition and directed conversion mechanism of Xinjiang middle-and low-rank coal is crucial for developing non-fuel utilization technology.In order to achieve directional depolymerization of organic matter in in Xinjiang middle-and low-rank coal and obtain soluble portions with simple composition in high yield under mild conditions,metal-acidic support composite（Ni/Si O₂ and Ni/ZTMS）,solid super acid（TFMSA/CNOFW）and solid base（NiM/Al₂O₃）were designed as catalysts in this thesis.Several coal-related model compounds were used as probes to evaluate the catalytic hydroconversion（CHC）activity of the above catalysts and the mechanism of active hydrogen formation and transfer during the CHC.Taking Runbei lignite（A）and Shaerhu subbituminous coal（B）in Xinjiang as the research object,the extraction portion（EP_A and EP_B）and extraction residue of A and B（ER_A and ER_B）were obtained by ultrasonic extraction with isometric carbon disulfide/acetone mixsolvent（IMCDSAMS）.The catalytic hydro-upgrading of EP,catalytic hydrocracking and ethanolysis of ER and the related reaction mechanisms were investigated and the following results were obtained:（1）Ultrasonic radiation extraction of A and B and catalytic hydrorefining of EP_A and EP_Bover Ni/Si O₂A and B were extracted by IMCDSAMS with ultrasonic radiation at room temperature,and the yields of EP_A and EP_B were 16.5%and 11.8%,respectively.The results observed by scanning electron microscopy（SEM）showed that the morphology of EP was irregular sheet-like stacking and the surface of ER was smoother than that of corresponding raw coal.A series of alkyl-substituted arenes and oxygen-containing compounds（OCOCs）were detected in EP_A and EP_Bby the gas chromatography/mass spectrometry（GC/MS）with total relative contents（RC）of 45.5%and 64.7%,respectively.EP_A and EP_B were subjected to CHC over Ni/Si O₂ under initial hydrogen pressure（IHP）of 4 MPa at 220 ^oC to obtain catalytically hydroconverted EP_A and EP_B（CHEP_A and CHEP_B）.Only alkanes and cyclanes,of which cyclanes are important liquid chemicals,were detected with GC/MS from CHEP_A and CHEP_B.The time profiles of the products from the CHC of 4-cumylphenol and 1,3,5-triphenylbenzene over Ni/Si O₂revealed that Ni/Si O₂ can activate H₂ to H…H and heterolytically cleave H₂ to relatively mobile H⁺and immobile H^-.H…H addition to benzene ring causes arenes hydrogenation and H⁺addition to the oxygen in the resulting the hydrodeoxygenation of OCOCs.Moreover,Ni/Si O₂ exhibited excellent stability and reusability after 4 runs and can be recovered by reduction with H₂ at 500^oC for 4 h.（2）Catalytic hydrocracking of ER_A and ER_BThe calcined nickel-organic framework（CNOFW）was prepared by pyrolysis,and the magnetic solid aicd TFMSA/CNOFW was prepared by impregnating trifluoromethanesulfonic acid（TFMSA）on CNOFW at room temperature.The catalyst can effectively activate H₂ and ethanol with excellent hydrocracking activity.In n-hexane system,compared with non-catalytic reaction,the introduction of TFMSA/CNOFW dramatically improved the yield of n-hexane soluble portions（HSP_A and HSP_B）from the catalytic hydrocracking of ER_A and ER_B（from 16.9%and 14.1%to 47.3%and 35.8%,respectively）.In addition,Abundant aromatics and OCOCs were detected in HSP_A and HSP_B without any cyclanes,indicating that TFMSA/CNOFW efficiently promoted the cleavage of>CH-O-bridge bond in ER_A and ER_B without hydrogenation of aromatic rings.The strong acidity of facilitated the free H⁺from the heterolytic H₂,which was transferred to the oxygen atoms on the bridge bonds in ER_A and ER_Bor to the substituents of the aromatic rings connected by the bridge chains leading to the breakage of the bridge bonds.The composition of HSP_A and HSP_B was relatively simple,which was conducive to obtaining pure organic compounds though subsequent separation.In ethanol system,the yields of ethanol soluble portion（ESP_A and ESP_B）obtained by the catalytic hydrocracking of ER_A and ER_B over TFMSA/CNOFW were as high as 51.5%and42.9%,respectively.According to the analysis of GC/MS,the OCOCs in ESP_A and ESP_B were dominant in phenols and ethyl esters,indicating that the cleavage of>CH-CH<and>CH-O-bonds occurred during the catalytic ethanolysis.The surface morphology of catalytic ethanolysis residue(R_E-Aand R_E-B)showed pore-and vein-like structures,respectively.Pyrrolic nitrogen and pyridinic nitrogen were dominanted in the nitrogen-containing species on the surface of R_E-Aand R_E-B.These heteroatom-rich derivatives were considered as ideal precursors for the preparation of N,O-self-doped porous carbons for high performance supercapacitors.（3）Two-step catalytic depolymerization of ER_A and ER_BNi/ZTMS was prepared by loading Ni into zeolite topology molecular sieve（ZTMS）prepared from coal fly ash.Ni/ZTMS exhibited the excellent>CH-O-bond cleavage activity.2-phenylphenol,as a coal-related model compound,was completely converted and the yield of target product bicyclohexane reached up to 97.7%over Ni/ZTMS under 4 MPa of IHP at 240 ^oC.In the first stage,the RCs of cyclanes in the soluble portions(SP_1-A and SP_1-B)of ER_A and ER_Bcatalyzed by Ni/ZTMS were 31.9%and 64.8%,indicating that the cleavage of the>C_alk-O-,hydrogenation of aromatic ring and the removal of heteroatoms（especially oxygen atom）occured simultaneously during the CHC process.Ni/ZTMS activated H₂ to H…H and heterolytically cleave H₂ to relatively mobile H⁺and immobile H^-due to the synergic activation of H₂ over NNPs and stong Lewis acid sites.The resulting H…H and H⁺played a vital role in aromatic ring hydrogenation and heteroatoms removal.The magnetism of Ni/ZTMS facilitated the rapid separation and recycling.In the second stage,alkanes and arenes were predominant in the soluble portions(SP_2-Aand SP_2-B)catalyzed by TFMSA/CNOFW,indicating that the cleavage of>C_ar-C_alk/>C_alk-C_alk is the dominant reaction in the second stage.A comprehensive analysis and evaluation of the two-stage products revealed that SP_1-A and SP_1-B rich in cyclanes and hydroarenes in the first stage has the potential to be refined into clean liquid fuels,while SP_2-Aand SP_2-Bdominant by aromatics and OCOCs in the second stage could be obtained as platform chemicals through subsequent separation and purification.（4）Catalytic alcoholysis of ER_A and ER_BNiRu/Al₂O₃,a bimetallic layered mesoporous material,was prepared with layered double hydroxide（LDH）as precursor.The medium and strong basic NiRu/Al₂O₃presented a hydrangea-like shape formed by the stacking of a large number of thin nanosheets.Ni and Ru nanoparticles were uniformly dispersed on the surface of the layered nanosheets and the strong interaction with Ni and Ru.In the isopropanol system,ODN was completely converted under 180 ^oC and 2 MPa INP over NiRu_2%/Al₂O₃ and the total total RC of naphthalene and tetralin was up to 84.9%due to the synergistic effect of H…H,H.and H^-.The yield of soluble portion（ISP_A,60.4%）from the hydrocracking of ER_A over NiRu_2%/Al₂O₃ was much higher than that of non-catalytic(ISP_A-N,47.7%).According to GC/MS,the RC of OCOCs in ISP_A-N was up to 96.2%,of which 89.2%were phenols.In addition to OCOCs,abundant arenes and cyclanes were also detected in ISP_A,indicating that NiRu_2%/Al₂O₃ activated the formation and transfer of H^-and H…H.Not only did they efficiently cleave>C-O-but also promoted the in-situ removal of oxygen atoms in phenols and aromatic ring hydrogenation.In the methanol system,toluene and phenol were the main products of the catalytic hydrocracking of benzyloxybenzene（BOB）over NiRu_2%/Al₂O₃.It is presumed that H.generated by methanol reforming was the main active hydrogen species,which promoted the cleavage of>C_alk-O-in BOB.The soluble portions of ER_A and ER_B methanolysis（MSP_A and MSP_B）,extracted by ether enriched and enriched abundant methyl phenols,are important platform chemicals.（5）Catalytic hydrocracking and hydrogenation of ER_A and ER_BThe mesoporous catalysts NiM/Al₂O₃（M=Zn,Mg and Ca）were prepared by in-situ coprecipitation method.Ni Ca/Al₂O₃ with medium strong basic showed the highest catalytic activity and could promote the cleavage of various bridge bonds dominant by>C-O-without hydrogenation of aromatic ring at low IHP（1 MPa）.Interestingly,OBMDB was completely converted to toluene over Ni Ca/Al₂O₃ at 180 ^oC and 1MPa IHP.ER_A and ER_B were subjected to catalytic hydrocracking over Ni Ca/Al₂O₃ under IHP of 1 MPa at 180 ^oC to obtain soluble portion(SP_A-1 and SP_B-1).Only alkanes dominated by n-alkanes and arenes dominated by naphthalene and its homologues were detected in SP_A-1 and SP_B-1.Alkanes endowed in coal or originate from the cleavage of>C_ar-C_alk in the macromolecular structure,while arenes are generated by the cleavage of>C-O-and/or the in-situ deoxygenation of phenols.The basicity of Ni Ca/Al₂O₃favored the heterolytic H₂ to obtain free H^-,which is transferred to the carbon atom adjacent to the oxygen atom in ER_A and ER_B resulting in the cleavage of>C-O-bonds.The relatively simple composition of the derivatives can be used to obtain value-added chemicals through subsequent enrichment and separation.At high IHP（5 MPa）,Ni Ca/Al₂O₃ exhibited the excellent hydrogenation activity,and the selectivity of perhydrophenanthrene obtained by the CHC of 9-phenanthrol up to 95.6%at 180 ^oC.ER_A and ER_B were subjected to catalytic hydrogenation over Ni Ca/Al₂O₃ under 5 MPa IHP at 180 ^oC to obtain soluble portion(SP_A-2 and SP_B-2).In addition to alkanes,only cyclanes dominated by non-substituted cyclanes,alkyl-substituted cyclanes and perhydrophenanthrene were detected in SP_A-2 and SP_B-2,among which bicyclohexane dominanted in SP_A-2 with the yield of 22.3%.更多还原