| Lignites are abundant in Xinjiang,but coal consumption is mainly concentrated in power production and coking industries,leading to great pressure on the environment.Lignite utilization is severely limited due to its high ash yield,high moisture content,and low calorific value.Therefore,it is necessary to insight into the compositions and structural features of organic matters in lignite at molecular level,which is of great significance for effective utilization of Xinjiang lignites and strategic transformation of coal resources in Xinjiang region.In this paper,Xinjiang Yinggemajianfeng lignite（YL）was taken as the research object.The effects of IL on YL structure and the structural composition of YL were investigated by three steps of ionic liquid（IL）,catalytic conversion and oxidation.YL was treated with a co-solvent system of IL-solvent and the co-solvent system was optimized.The results show that solvent has little influence on the yield of methanol soluble matter from TYLs（YL treated with IL）and the optimum solvent volume was 20 mL.The yield of methanol soluble matters from YL treated with IL-methanol is significantly higher than that from YL treated with IL alone,indicating that the co-solvent system could improve the solubility of YL,because methanol could reduce the viscosity of IL and increase the interaction between IL and some components in YL,thus promoting the release of these components.SEM,TG/DTG,FTIRS and solid 13C NMR were used to characterize YL and TYLs.It was found that the co-solvent system could destroy the crosslinked network structure of coal and TYL is more suitable for liquefaction and pyrolysis than YL.Solid 13C NMR analysis also displays that each cluster in YL has 3 aromatic rings on average,and each aromatic ring has an average of 2 substituents.There are a large number of short bridges or side chains in the carbon skeleton structure of YL.The CPP-GC/MS analyses of YL and TYLs exhibit that the major components of YL and TYLs are alkanes,alkenes,aromatics,and phenols.The oxygen-containing compounds in TYL is relatively low,indicating that IL could bring out some oxygen-containing compounds from YL due to hydrogen bonding.The Pd-Ru/HZSM-5 catalyst was prepared and its activity and reaction mechanism were investigated by using 2-（benzyloxy）naphthalene（BON）as the lignite-related model compound.According to characterization with SEM,XRD and XREPS,Pd and Ru active components of Pd-Ru/HZSM-5 catalyst were successfully loaded onto the support,and the particles were dispersed and evenly distributed in the form of nanosheets.The optimum reaction temperature and time were 210 oC and 2 h,respectively,and the corresponding BON conversion rate reached 100%.BON only undergoes a cleavage reaction under the condition,and the products only contain toluene and 2-naphthol.The catalytic conversion results of YL and TYL show that the yield of catalytic pyrolysis products from YL and TYL was 41.5%and 53.0%,respectively,which is again proven that TYL is more suitable for liquefaction than YL.The APCI QOTMS analysis of the soluble matters from YL and TYL indicate that the main components of YL are O1,hydrocarbon,N1and O2 class compounds,while the relative content of O2,O1,N1 and O3 class compounds in TYL are higher,indicating that TYL dissolved a large number of hetero-containing compounds during the catalytic transformation,especially O2-O4 class compounds.O1 class compounds are mainly arenols and indenols.The main compounds in O2 class are aryl diols and alkoxyphenols.O3 class compounds mainly represent aryl triols and alkoxybenzenes.The relative content of O4 class compounds are smaller,mainly belong to alkylphthalate.The DART/TOF-MS analyses of carboxylic acid and ester model compounds find that the ionizating gas temperature over 300 oC and organic solvent have little effects on model compounds ionization with DART.The model compound concentration plays an important role in model compound ionization.The suitable concentrations of different model compounds are different.The suitable concentrations of methyl benzoate,dimethyl phthalate,dimethyl adipate,phthalic acid and adipic acid are 0.10,0.10,0.05,0.10,and 0.05 mol/L,respectively.The typical ions of 3 methyl esters are[M-OCH3]+,[M+H]+,[M+NH4]+,and[2M+NH4]+.The ions formed from phthalic acid and adipic acid are mainly polymer ions,indicating that there is a strong intermolecular hydrogen bond between carboxylic acids.The final residue of YL via thermal dissolution was subjected to ruthenium ion-catalyzed oxidation,and the carboxylic acids-phase（CAP）and the esterified products（MECAP）were analyzed with DART/TOF-MS.The results demonstrate that abundant alkanoic acids and alkanedioic acids exist in CAP and dimethyl alkanedioates are the major component in MECAP,indicating that the presence of abundant aromatic bridgehead bonds in YL.It is confirmed that DART/TOF-MS can rapidly analyze carboxylic acids and esters,which is helpful to understand the macromolecular structural characteristics of coal through oxidation and provide an analytical method for the value-added utilization of lignites.This thesis contains 48 Figures,70 Tables,and 209 references. |
