| Soot, sulfur dioxide and nitric oxide are released when coal burns as energy source, which has increasingly aggravated the pollution of environment. On the other hand, because coal contains aromatic ring compositions, a lot of aromatic compound monomers , which can be synthesised into important polymer, can be gained from coal's liquid ramification. So, the research on the new arts and crafts for effectively preparing chemical substance and chemical material under mild and clear conditions have become an important strategic target of 21st coal chemical industry .The study of coal structure by solvent extraction has been developed for a century. Especially, the solvent extraction of coal by using carbon disulfide-N-methyl-2- pyrrolidinone (CS2-NMP) mixed solvent and some electron donor compounds such as tetracyanoethyene (TCNE) and p-phenylenediamine (PDA), could separate organic compounds from inorganic compounds completely, make good precondition for qualitative and quantitative analysis of organic compounds in coal. The extract contains no mineral, could be called "clear and super-fine powder coal". Meanwhile, compared with the original coal, the pore structure, pore distribution according to radius and specific surface area of the extract residue have been changed. So the porous solid material with excellent adsorptive properties can be gained from such residue.Yunnan lignite and Nantong bituminou coal were extracted with carbon disulfide- N-methyl-2-pyrrolidinone(CS2-NMP) mixed solvent at room temperature, and the CS2-NMP extract was extracted by Acetone and Pyridine in turn. Then the composition of the two kinds of coal's Acetone extracts was tested by GC/MS apparatus, and the granularity, Nitrogen's sorption behaviors of extract residues were tested by using scanning electron microscope and Accelerated Surface Area and Porosimetry (ASAP) 2010 apparatus. The experimental results showed that: (1) The solvent extraction could reduce the coal granularity and make the coal granules more even. (2) The adsorption property of residues was similar to that of original coal with low extract yield, whereas the adsorption ability increased greatly for the coals with high extract yield. (3)In the course of extraction, with the removal of small molecular substances, Nantong bituminous coal agglomerate structures was loosened, Nitrogen molecule penetrated into the texture of coal more easily, then the total surface area and the volume of all kinds of pores in coal were enlarged. (4)The definite linear correlation was observedbetween Nitrogen adsorption volume and relative pressure in a large relative pressure range. (5)The mix-acid could not change the shape of pores during demineral , whereas the extract by organic solvent can "broaden" the pores and change their shapes. (6)The solvent extraction could not change the micropore distribution obviously. The enlargement of the total surface area and the volume of all kinds of coal was mainly due to the increase of pore number in different pore size range , this proved that solvent extraction could not destroy the coal molecular dimensional network composed by basic structural units. Therefore, coal solvent extraction should belong to physical reaction in nature. (7)The radius of Nantong bituminous coal colloid structure unit was calculated to 2.4nm according to the most probability of pore radius. (8) The Acetone soluble (AS) fractions of two coal's sample mainly include chain hydrocarbons, aromatic compounds, mixed-atom compounds and oxygenous ramifications. Mixed-atom compounds mainly are nitric compounds such as ergostas and oxygenous compounds such as hydroxybenzene and ester. Aromatic compounds are mainly benzene's ramification.As a second-level extract fraction of coal, AS fractions do not contain sulfide, phosphide and polymer-ring aromatic compounds.As a clear, excellent adsorbent and porous material, solvent extracts of coal can be widely used as catalyzer carrier, decolorant of coloured- substance and adsorbent of metal ions and impurity. The... |
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