Research On Mechanisms Of Bio-liquefaction Of Fushun Long Flame Coal And Its Model Compounds By White Rot Fungi Hypocrea Lixii AH

In China, low rank coal is abundant, accounting over 45% of Chinese coal resources. The clean and efficient use of low rank coal rouses interest worldwide, due to the low-rank coal properties of low heat value, high moisture content, easy weathering and spontaneous combustion. Compared with conventional chemical liquefaction, gasification, coking and power generation of low rank coal, bio-liquefaction has some distinct advantages, for example, of operating at mild reaction conditions with environmental friendliness. However, industrial application of coal bio-liquefaction is hindered in recent years, because of its low conversion efficiency, complicated liquefaction products and unclear reaction mechanisms.As such, first, this thesis screened strains from nature in terms of high liquefaction ability and their physiological and enzyme production properties were studied. Second, the effects of conversion conditions on bio-liquefaction of Fushun Western Open coal and on solubilised coal were investigated. Third, given the complexity of coal structure, macromolecular structure models of low rank coal was built based on the chemical analysis of coal structure. In the last step, instead of directly studying coal as conversion feedstock, the coal model compound was used for the study on coal bio-liquefaction mechanisms.A fungus that can liquefy Fushun coal was screened from soil. It was further identified as Deuteromycotina Moniliales Hypocrea based on the analysis of its 18S rDNA sequencing and phylogenetic tree using Clustal X and Mega 4.0. It was then named Hypocrea lixii AH. The analysis of enzyme production showed that Hypocrea lixii AH had the ability of producing coal-degradation enzymes including peroxidase, polyphenol oxidase (PPO), lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (Lac).The liquefaction ratio of bio-liquefaction of nitric acid treated Fushun coal (ρ<1.3 g/cm3) was up to 44.86% by Hypocrea lixii AH. This fungus liquefied more coal in shaker than in static incubator, in fermentation broth than in extracellular broth, and in fermentation broth induced by coal than in that without induction. The corresponding liquefaction ratios were than 23.25%, 14.09% and 4.67%, respectively. Moreover, Bio-liquefaction future improved by adding surfactants, which promoted the adsorption of extracellular proteins/enzymes onto coal surface.The solubilized coal has a strong chemical polarity. They were only completely dissolved in methanol, partly soluble in alkaline solutions and insoluble in acids. By using UV-Vis, FTIR, 1H NMR, ¹³C NMR and GC-MS analysis, it was found that the products were rich in aniline, amide and ether, etc., the aromatic ring number was 1-3 and the aromatic carbon ratio was 0.328. Measured by gel chromatography, its molecular weights (kg/mol) were near 3153 and 427, and down to near 1299, 367 and 115 after 90 d. However, measured by MS, its molecular weights (Da) were near 3580, 2930, 1741, 883 and 470, and after 90 d also down to near 1740, 900, 883, 680, 470 and 288.Integrating with elemental analysis, extract liquor analysis, analysis of peak separation of the FTIR,and ¹³C NMR spectrum of Fushun coal, the Fushun coal macromolecular structure model was developed. The molecular formula of oxidized coal structure model was C₁₉₂H₁₆₁N₉O₃₉. Based on Fushun coal macromolecule structural models, thymol, phenolic and side chain model compounds, benzoic acid, oxygenic aromatic model compounds and quinoline, nitrogen model compounds, were chosen to be degraded by H. lixii AH. Degradation products were analyzed by UV-Vis, FTIR, GC and GC-MS. Degradation mechanisms of thymol, bezioc acid and quinoline were mainly related to LiP, Lac and PPO, which removed methyl, opened ring, hydroxylated and oxidized.Alkaline dissolution occurred during Fushun coal bio-liquefaction because the pore volume increased from 1.634 m²/g to 175.7 m²/g, ash from 7.06% to 13.03%. By comparing structural parameters such as f_a of Fushun coal, solubilized coal and residual coal, the results showed that aromatic carbon ratio reduces, side chain elongates, and terminal methyl and carbon connected with O increases, indicating that rings opening, bonds breaking and oxidation reaction occourred. LiP and Lac catalyzed to open aromatic cycles and break bonds; esterase catalyzed to break ester bond; and peroxidase took part in oxidation reaction.All the above results showed that H. lixii AH had the ability to liquefy Fushun coal. This thesis would help improve future industrial application of coal bio-liquefaction by providing basic but important data on bio-liquefaction of coal and by partly explaining bio-liquefaction mechanisms.