Preparation Of Bifunctional Catalyst And Application For Catalytic Hydroconversion Of Shanbei Hecaogou Subbituminous Coal

In the context of rapid economic and social development with the dual constraints of energy consumption and environmental capacity,it is extremely urgent to explore the new technological path for efficient and high-value utilization of resources.The reserves of subbituminous coal（SBC）in northern Shaanxi account for 15 wt%of proven reserves in China.The natural advantage of SBC is rich in aromatic rings（ARs）and bridge with heteroatomic units,which can dissociate them into soluble portion（SP）.Subsequently,the organic structure characteristics of SP are analyzed and directional conversion is achieved,and the new technology path of high-value utilization is developed under mild conditions.In this thesis,based on the complex organic components of SBC derived liquid,4 different bifunctional catalysts were prepared,including Ni/HZ-5（n）,Ni/CZ,Ni/MPYZ,and Ni-Co/HPZY.The physical and chemical properties of bifunctional catalysts were investigated.The effects of metal loading method,different metal and loading,acidity and strength of different supports,and macromolecular accessibility were invertigated in the model compound for the catalytic hydroconversion（CHC）reaction.Taking Hecaogou SBC（HSBC）as the research object,3strategies were proposed to obtain the cascade derivative liquid,including the isometric carbon disulfide/acetone mixed solvent（IMCDSAMS）extraction portion（EP）of HSBC,the ethanololysis soluble portion（ESP）of inextraction portion（IEP）,and the ethanololysis soluble portion（ESP）of HSBC.Different bifunctional catalysts are selected to CHC the cascade derivative liquid to obtain different grades of clean liquid fuel.Further,the composition and organic structure characteristics of cascade derivative liquid,clean liquid fuel,and residues were comprehensively analyzed and researched.Based on the different components in characteristics,the structure of bifunctional catalyst,and the detailed distribution of products were used to investigate the possible reaction mechanism and optimize the corresponding strategy.（1）Different methods are used to prepare different bifunctional catalysts.Enhance the catalytic cracking performance of solid acid support by adjusting the pore structure,accessibility,and acidic sites distribution.Strengthen the catalytic hydrogenation performance of metal active center by different loading methods,uniformly dispersed metal Ni and Ni-Co nanoparticles on the supports.The relationship between the strength and number of acidic sites of different Ni/HZ-5（n）bifunctional catalysts were investigated qualitatively and quantitatively.A large-size FAU composite zeolite（CZ）support with 2 nm mesoporous pores synthesized by braiding a coffin like MFI structure,and a modified deposition-precipitation method was used to prepare a strong L acid sites and suitable B/Lvalue Ni/CZ.Mesoporous Y zeolite（MPYZ）support with defects and mesoporous diameter of about 5.5 nm was synthesized,and a modified deposition-precipitation method coupled with oxidation-reduction was used to prepare Ni/MPYZ with high loading,nanoparticles and uniform dispersion,significantly enhanced B and L acid sites.The hierarchical porous zeolite Y（HPZY）support was synthesized,and the bimetallic Ni-Co/HPZY was prepared by in-situ decomposition of NTC coupled with modified deposition-precipitation method.（2）Low-rank coal related model compounds（LRCRMCs）with different>C_ar-O-and>C_al-O-bridge bonds were used as substrate molecules to investigate the CHC catalytic activity of Ni_13%/HZ-5（n）,Ni_10%/CZ,Ni_10%/MPYZ,and 10Ni-3Co/HPZY.The selectivity of the target product is affected by the strength of the accessible acidic sites and the morphology of the metal Ni or/and Co active center.And then,the hydrocracking reaction activity of>C-O-bridge bond is significantly enhanced by optimizing the accessibility and strength of acidic sites.ARs are efficiently hydrogenated to produce cyclanes by promoting the homogenization and smaller particle size dispersion of Ni active center.Based on the intermediate product distribution and transition state theoretical calculation,the bifunctional catalyst can activate H₂to H???H under mild conditions,and then split to an immobile H^-and a relatively mobile H⁺,the active species（H???H,H^-,and H⁺）can efficiently achieve the hydrogenation saturation of ARs and remove O atoms through the synergistic effect in the CHC reaction.Therefore,it is a direct and effective strategy to improve the catalytic performance of bifunctiaonal catalysts in CHC reaction to reconstruct the synergy between acidic accessibility sites of supports and metal active center.In addition,it can effectively achieve the rearrangement and hydrogenation of ARs to obtain polycyclic alkanes under the synergistic effect of strong acidic accessible sites and metal active centers,which provides a theoretical basis for obtaining of high-density liquid fuel.（3）HSBC was exhaustively extracted with IMACDSMS under ultrasound radiation（USI）to obtain extractable portion(EP_HSBC)with 18.4%yield.SEM morphology analysis shows that EP_HSBC has a small particle with agglomeration.Thermogravimetric analyzer（TGA）analysis shows that ARs and heteroatoms in EP_HSBC are combined by covalent bonds with different forms and strengths.In catalytic hydroconverted EP(EP_CHC),cyclanes,alkenes,and dehydroaromatics are added,and the content of chain alkanes（CAs）increased by 21.7%,ARs are almost hydrogenated,oxygen-containing organic compounds（OCOCs）are reduced to 1.1%,and nitrogen-containing organic compounds（NCOCs）are not detected.Ni_10%/CZ shows high catalytic activity for ARs hydrogenation and>C-X bridge bonds cracking performance in CHC reaction of EP_HSBC,which can convert EP_HSBC into clean liquid fuel.（4）IEP was efficiently ethanololyzed to obtain ESP_IEP with 14.8%yield.The surface morphology of ESP_IEP is smooth and agglomerated.TGA analysis shows that ARs and heteroatoms in ESP_IEP in structure are different forms and strengths of bonding.The organic functional groups（FGs）in ESP_IEP has changed significantly under CHC reaction on Ni_10%/CZ。In detail,the content of CAs in ESP_CHC has increased 23.4%,and OCOCs has reduced to 7.1%,cyclanes and dehydroaromatics are added,and no NCOCs and SCOCs are detected.Correspondingly,during the CHC,the O₄ species were converted into O₁-O₃ species and decreased significantly.Ni_10%/CZ shows high catalytic activity for ARs hydrogenation and>C-X bridge bonds（especially O atoms）cracking performance in CHC reaction of ESP_IEP,and the component of ESP_IEP can be efficiently convert into clean liquid fuel.（5）HSBC was efficiently ethanololyzed to obtain ESP_HSBC with 21.2%yield.After deep hydroconversion（DHC）reaction on 10Ni-3Co/HPZY,the organic FGs in ESP_DHC changed obviously,the content of hydrogenated ARs increased,but the heteroatom-containing FGs in ESP_DHC decreased significantly.In ESP_DHC,the content of CAs increased by 18.1%,ARs and OCOCs are reduced to 0,cyclanes and dehydroaromatics are added,and cyclanes are mainly alkylcyclanes and polyalkylcyclanes,no NCOCs are detected.In addition,the H/C ratio increases significantly and O/C ratio decreases sharply in ESP_DHC after DHC,further indicating that 10Ni-3Co/HPZY has a high activity for hydrogenation and rearrangement aromatics and cracking>C-X bridge bonds to remove heteroatoms efficiently,which can convert ESP_HSBCinto high-density liquid fuel.（6）For the analysis of the structure of HSBC and non-destructive residues:the region of aliphatic carbon and aromatic carbon are almost the same,but the aliphatic carbon region in IEP,ethanololyzed residue of IEP（R_E）,and ethanololyzed residue of HSBC(R_HSBC)is obviously weaker the the aromatic carbon region.In detail,the molar mass of aromatic carbon（f_a）decreases in the order of HSBC>IEP>R_E>R_HSBC,the molar mass of aliphatic carbon(f^a_al)decreases in the order of HSBC>IEP>R_E>R_HSBC,and the average length of methylene chain（C_n）decreases in the order of HSBC>R_HSBC>IEP>R_E.XRPES shows the surface of HSBC and non-destructive residues(IEP,R_E,and R_HSBC)are dominated in C and O elements,and oxygen-containing FGs include>C-OH,>C=O,>C-O-,and>COO-.FTIRS analysis shows that the fitting adsorption peaks of ARs vibration in IEP,R_E,and R_HSBC migrate towards the low wavenumber range and tend to be normalized.Additionly,the mass loss rate of HSBC and non-destructive residues in the temperature range of 150-840 ^oC gradually decreases in the order of IEP>R_E>HSBC>R_HSBC.CPPC-GC/MS analysis shows that the content of CAs and alkenes volatile organic species in HSBC and non-destructive residues are dominant,and the content of ARs increases in the order of IEP<R_E<HSBC<R_HSBC.Some ARs may be present in the nested group of coal structural molecular,and the RE can be used for hierarchical porous carbon meterials.This thesis contains 102 Figures,65 Tables,and 237 references.