| As a valuable non-renewable resource, the developments of new theories and new technologies for the non-energy fields (such as fine chemicals) application of coal should be vigorously strengthened to make full and effective use of its structural characteristics and potential advantages (such as rich in condensed aromatic ring and heterocycle, and terpenes and pinene compounds with biological activity etc.), which is greatly significant for saving resources, high value-added use of resources and reducing environmental pollution. In this paper, taking Shenfu coal as research objective, the photocatalytical oxidation reactivity of coal and it macerals were investigated through photocatalytical oxidation to provide a theoretical basis and basic data for preparation fine chemicals by photocatalytic oxidation of coal.The effects of photocatalytic oxidation process conditions on the yield of humic acid of the photocatalytical oxidation of Shenfu coal were studied systematically. The results showed that, the smaller the size of coal particle, the higher photocatalytical oxidation reactivity of coal was. Minerals in coal could catalyze the photocatalytical oxidation reaction. Removal of mineral from coal led to decrease in its photocatalytical oxidation reactivity. FeCl3 also had catalysis effect on photocatalytical oxidation of Shenfu coal. Meanwhile, it was found that the formation of humic acids during photocatalytical oxidation of coal showed competitive reactions between formation and decomposition of humic acid. When the decomposition rate of humic acid increased, the content of humic acid declined, on the contrary, when the formation rate of humic acid increased, the content of humic acid increased.The vitrain (SFJM) and the fusain (SFST) were hand-selected from Shenfu coal. Then the photocatalytical oxidation reactivity of different maceral was studied by using photocatalytic oxidation, FTIR analysis, Cascade Solvent Extraction, GC/MS and SEM. The results showed that the photocatalytical oxidation reactivity of different maceral varied. Generally, the order of oxygen content in the photooxodation products from different maceral was in the sequence of Shenfu row coal (SFYM)> (SFJM) > (SFST). The yield of free humic acid showed a similar trend. Free humic acid content was higher in SFJM ,but total humic acid content basically equal in SFJM and SFST. These indicated that SFST could catalyze the photocatalytical oxidation of SFJM to form free humic acid during the photocatalytic oxidation of SFYM. And the photocatalytical oxidation of other functional groups like alkyl ether may also occur during the photocatalytic oxidation process.Further study showed that significant changes of the types of hydrogen bonds in coal were took place during the photocatalytical oxidation process. After the photocatalytical oxidation, Self-associated and OH-Ï€hydrogen bond significantly increased, while OH-N, cyclic OH teteramers, OH-O (ether) hydrogen bond and free OH group significantly reduced. C-H bond in aromatic ring took part in the oxidation reaction either. Aromatic structure units were selectively decomposed during photocatalytic oxidation. At the same time, branched alkyl chains and terpenes derivatives were subjected to oxidation decomposition... |
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