Step-Catalytic Reaction Separation Of The Petroleum Ether Insoluble Fraction Of Heavy Oil Of Medium And Low Temperature Coal Tar

There are many important chemical products in coal tar.Therefore,the separation,identification,and then processing and utilization of its composition are important.In this paper,the heavy components(P-CT,petroleum ether extraction residue)from heavy oil of middle and low temperature coal tar in northern Shaanxi is studied.The catalytic reaction(chemical polymerization)-step extraction-acid-base scrubbing method is used to obtain information on its structural composition.First of all,according to the composition characteristics of P-CT,phenol,methyl phenol and naphthol were considered as model compounds to explore its reactivity with aldehydes.Then P-CT and three aldehydes(37%formaldehyde solution,paraformaldehyde,furfural)were polymerized separately in a homogeneous system to investigate the reactivity of different aldehydes with P-CT and the products were separated by gradient extraction.Next,the products of each gradient was volatilized at the final temperature of 300 ? with TG(thermogravimetry),and the remaining components were subjected to be acid-base treatment.Finally,Each component was characterized by PY-GC-MS,FT-IR,TG-FTIR to achieve the composition and structure of the compounds in the heavy components of coal tar extremely.The results show that the reactions of model compounds with aldehydes are mainly para-nucleophilic substitution.And the larger residual carbon of the product is due to the strong stability of methylene bond between the phenolic nucleus.The reactivity of naphthol and aldehydes is low,but the aromatic ring of naphthol participates in the main chain of resin,which makes the carbon residue of resin increase.The analyses from above provide the experimental basis for the reaction between P-CT and aldehydes.The contents of phenols in JM,DM,and KM were 12.17%,22.76%,and 32.02%,respectively,Which reduced significantly,compared with the contents of phenols(50.59 %)of P-CT,while the contents of aromatics increased.This shows that the aldehydes can effectively remove the phenols in P-CT and enrich the aromatics.It is also found that formaldehyde has the best effect on cutting back phenols comparing with the other two aldehydes.The reaction products were divided into toluene soluble(TS),toluene insoluble but tetrahydrofuran soluble(TI-THFS)and tetrahydrofuran insoluble(THFI)by toluene and tetrahydrofuran.Analyses of the TS components reveal that JM-TS(toluene solubles of JM),DM-TS(toluene solubles of DM),and KM-TS(toluene solubles of KM)are mainly composed of aromatic hydrocarbons.Their contents are 49.12 %,59.20 % and 53.18 %,respectively.All of them are mainly aromatic hydrocarbons containing three benzene rings,following by bicyclic aromatic hydrocarbons and tetracyclic aromatic hydrocarbons.The TI-THFS fraction is mainly enriched in ethers.The THFI fraction is mainly composed of fused ring aromatic compounds containing phenolic hydroxyl groups.Comparing the thermogravimetric analysis of P-CT and its components,it is found that the residual carbon of the product and its components increase after the reaction.It is indicated that the polymerization reaction has the formation of macromolecules,which makes its thermal stability increase.The formation of methylene bridging in the product is the reason for its increased thermal stability.And it is found that furfural and P-CT have the best degree of polymerization comparing with the other two aldehydes.It is found that the benzo(a)pyren-ol and hydroxypyrene have also been found in the high-boiling(?300 ?)component in addition to alkylphenols,alkylnaphthols,indophenols and phenanthrenes by PY-GC-MS at the final temperature of 800 ?.