Ultrasonic Assisted Extraction Of Different Macerals From Yangchangwan Coal By Three Kinds Of Organic Solvents

The rich coal resources in Ningdong of Ningxia,Yulin of Shaanxi and Ordos of Inner Mongolia constitute the "Golden Triangle" of energy in China.However,in the process of utilization and exploitation of coal resources,there are often serious pollution problems.If we want to fundamentally solve these problems in the process of coal utilization,we must study coal from the molecular level to improve the efficiency of coal utilization.As a low destructive and convenient method,the organic solvent extraction at room temperature has its unique advantages in the field of exploring coal structure.However,the traditional extraction process is mainly based on the vitrinite in coal,and the extraction of inertinite is still in its infancy.In addition,the type of solvent is also a key factor affecting the extraction yield.In order to find out the extraction rule of different solvents and the difference of product distribution.In this paper,the vitrinite and inertinite of Ningxia Ningdong Yangchangwan(YCW)coal were extracted by three kinds of organic solvents:aliphatic hydrocarbon,aromatic hydrocarbon and alcohol in the presence of ultrasound at room temperature.The extraction products,extraction residues and two kinds of macerals were studied by means of industrial analysis,element analysis,13CNMR,XPS,XRD,FT-IR,BET and other modern analytical techniques.The 13CNMR and XPS results of vitrinite and inertinite of YCW coal show that the carbon in YCW coal is mainly composed of aliphatic carbon and aromatic carbon,and the content of aromatic carbon is much higher than that of aliphatic carbon.It was also found that the content of aliphatic carbon in vitrinite was higher than that in inertinite,but the content of aromatic carbon and carbonyl carbon was lower than that in inertinite.The extraction yields of three kinds of solvents are as follows:aliphatic hydrocarbon>aromatic hydrocarbon>alcohol.The extraction yield of aliphatic hydrocarbon solvent was the lowest,which was kept at 6-10%.The second is aromatic solvent,the extraction yield is 6-12%.The highest extraction yield is alcohol solvent,which can even more than 15%.Further analysis of the results showed that the solvent structure has a great influence on the extraction yield,and the flatter the structure,the higher the extraction yield.Secondly,it was found that the viscosity of the solvent was also an important factor affecting the extraction yield.The higher the viscosity,the lower the extraction yield,and the lower the viscosity,the higher the yield.In addition,the results show that the extraction yield of vitrinite from YCW coal is always higher than that of inertinite.The results of FT-IR and GC/MS from the three kinds of solvent extraction products showed that the distribution of the products from aliphatic hydrocarbons was similar to that from aromatic hydrocarbons,that is to say,the products of solvent extraction from aliphatic hydrocarbons had the highest content,followed by esters.The biggest difference between them lies in the distribution of n-alkanes in the products.For the aliphatic hydrocarbons extraction vitrinite,the main n-alkanes are n-36 alkanes and n-24 alkanes.In the aromatic hydrocarbons solvent extraction of vitrinite,n-alkanes are mainly n-21 alkanes and n-27 alkanes,while in the extraction of inertinites,n-alkanes are mainly n-36 alkanes and n-54 alkanes with larger volume and relative molecular weight.The distribution of the compounds in the products of alcohol solvent extraction is relatively uniform,which generally follows the rule of ester>aliphatic hydrocarbon>aromatic hydrocarbon.And the content of n-alkanes in the alcohol solvent products is generally low,mainly n-20 alkanes.There are a lot of aromatics in the alcohol extraction products,mainly in the form of naphthalene,phenanthrene and anthracene.The distribution of ester compounds in three kinds of solvent extraction products is similar,that is,the phthalate diester is the highest among all ester compounds.The FT-IR results of three kinds of solvent extraction residues show that both aliphatic and aromatic hydrocarbons can extract a lot of aliphatic hydrocarbons from YCW coal.The XRD results of three kinds of solvent extraction residues show that the d002 of all solvent extraction residues are increasing compared with vitrinite and inertinite before extraction,which indicates that the extraction process can increase the interlayer spacing of aromatic lamellae.After extraction the Lc decreased.The value of Nave changed little before and after extraction,the value is between 8-11.BET analysis of the residues from solvent extraction of aliphatic and aromatic hydrocarbons shows that the proportion of macropores in the residue is positively related to the extraction yield.The higher the proportion of macropores is,the higher the extraction yield is,and vice versa.The content of macropores in the extraction residue of vitrinite is higher than that of inertinite,which indicates that when the same solvent is used,the macropores of vitrinite are easier to form than inertinite,resulting in higher extraction yield of vitrinite than inertinite.