Study On The Transformation Of Acidic Functional Groups In Low Rank Bituminous Coals And Their Direct Liquefaction Products

In this paper three kinds of low rank bituminous coals (YuanPing coal, YangQu coal and DaTong coal named 386,387 and 388 respectively) were studied.The process of coal samples preparation is that. Firstly, the three coals were separated by zinc chloride solution with different densities in order to know the coal maceral composition. Secondly, HCl and HF solutions washed the three coals in order to the ash <2% in proximate analysis by weight. Then the traditional method for measuring acidic functional groups in low rank bituminous coal was improved. At last the mineral removed 386 and 387 liquefied in an autoclave before and after NaOH solution boiled. The carboxyl and phenol in low rank coals and their liquefaction products were determined by the improved traditional method. The results have been listed as followed:1. The fusinite rich and liptinite poor in 387 and 388, conversely The vitrinite poor and liptinite rich in 386. Additionally,387 and 388 are more hydrophilic than 386.2. The contents of carboxyl and phenol in 386,387,388 measured by traditional and Boehm methods were higher than the true value. Then the traditional method was improved.3. The improved method is that:carboxyl content was obtained at 0.15mol/L calcium acetate and 2h boiling time; total acids functional groups content were obtained at 0.25mol/L sodium hydroxide and 1h boiling time. The contents of carboxyl and phenol in coal liquefaction solid products can also be measured by this method.4. After liquefaction the analysis result is that the carboxyl in coal was in gas not in solid coal direct liquefaction products.5. The oil and gas yields of the NaOH solution treated coal liquefaction are lower than the NaOH solution untreated. This means NaOH solution is harmful for coal liquefied to oil, in other words, it seems that the acidic phenols in coal is good for coal liquefied to oil.6. The NaOH solution treated coal liquefaction solid products (asphaltene and preasphaltene) contain more phenol than the NaOH solution untreated. Besides the trend in 386 is more obvious than 387. It shows that the acidic phenols in coal have a good effect on the acidic phenols (native and derivative) migrating in residue.7. The FTIR analysis of the solid products (asphaltene, preasphaltene and residue) from NaOH treated and untreated coal liquefaction is that:NaOH treating is good to phenols transferring to asphaltene and oil for 386; and NaOH treating is good to phenols transferring to oil for 387.8. The main components of 387 liquefied oil are:xylene、indan、 cyclohexane、butylbenzene、ethylbenzene. The NaOH solution treated 387 liquefied oil contain no carboxylic acids, but contain more butylated hydroxytoluene.9. The thermal gravimetric analysis of 386 mixed with increased proportions of naphthol (the phenol carrier) reveals that the temperature of maximum weight loss rate decreased.