Investigation on Component Separation and Structure Characterization of Medium-Low Temperature Coal Tar

Abstract

Two medium-low temperature coal tars (MLCTs) derived from the pyrolysis of low-grade bituminous coal were separated into 11 narrow fractions by true boiling distillation. The primary property and chemical composition analysis of MLCTs and their distillate narrow fractions were investigated at the macroscopic and molecular level by gas chromatography-mass spectrometer (GC-MS) and proton nuclear magnetic resonance (1H NMR). The two MLCTs show obvious characteristics of medium-low temperature coal tar, including a high H/C, high-oxygen and nitrogen, low-sulfur, low-density, and low viscosity. As the boiling point increases, the molecular weight of each distillate fraction increases continuously. Meanwhile, the yield of each distillate fraction increases gradually, except for the 270–300 °C distillate fractions. The oxygen content in the 170–230 °C distillate fractions is much higher than that of the other distillate fractions. The dominant groups of compounds in the MLCTs were saturates, aromatics, and resins, and the resin content was above 24.5 wt%. The molecular composition of the below 170 °C fractions mainly consists of benzene, toluene, and xylene, and the main phenolic compounds in the 170–230 °C distillate fraction are low-rank phenols, such as phenol, cresol, and xylenol. Although the macroscopic properties of the MLCT-Z and MLCT-S were quite similar, the molecular composition, the group composition and hydrogen distribution in each MLCT and its narrow distillate fractions are still different. The present work has contributed to our present understanding of the composition of MLCTs and to the guiding of the efficient processing of MLCTs.

Exploring Medium and Low-Temperature Convective Geothermal Resources Through Controlled Source Audio Magnetotelluric Mothod

“…On the outer flanks of the hot spring area, gneisses, dacites and metagranites of the Da Shi Qiao Formation of the Liao he Group are exposed in order from the inside to the outside; gneisses, gneisses and hornblende of the Gao jia yu Formation of the Liao he Group; and metagranites, metavolcanic rocks, gneisses and dacites of the Lira yu Formation of the Liao he Group. In the western part of the hot spring area, there are outcrops of Huang Ling Zi amphibolite and diorite granite rocks [19]. The area consists mainly of fracture formations, the main ones being the north-east-trending Da Ying zi-Cao he Kou Deep Fault, about 130 km long and between 1 and 3 km wide, and the north-west-trending Xia mu Cheng-Sui Yan Fault, about 150 km in length.…”

Experimental Study on Vacuum Distillation Separation Characteristics of Tar Containing Solid Particles: Distributions of Light Components

“…Coal consumption in China accounts for more than 50% of primary energy, which is expected to be maintained for a long time. , Consequently, China’s recourse to mitigating the import pressure of oil and gas resources involved a reliance upon substantial coal resource production, particularly through coal tar production by pyrolysis. Coal tar production through pyrolysis refers to a mixed product containing a diverse array of intricate organic constituents obtained by heating coal to elevated temperature in an inert atmosphere and cooling the output pyrolysis gas. − A diverse array of valuable products, including coal tar, crude benzene, and semi-coke, could commonly be derived . Simultaneously, the hierarchical and qualitative utilization of tar holds the potential to facilitate the more efficient utilization of this resource.…”

“…Coal tar production through pyrolysis refers to a mixed product containing a diverse array of intricate organic constituents obtained by heating coal to elevated temperature in an inert atmosphere and cooling the output pyrolysis gas. 6 − 9 A diverse array of valuable products, including coal tar, crude benzene, and semi-coke, could commonly be derived. 10 Simultaneously, the hierarchical and qualitative utilization of tar holds the potential to facilitate the more efficient utilization of this resource.…”

Separation and thermal conversion of group components from medium‐low‐temperature coal tar pitch

“…Medium‐low‐temperature coal tar pitch (MLP) was a large number of by‐products in the process of preparing semicoke by pyrolysis of low‐rank coal 16 . It was the heavy component of medium‐low‐temperature coal tar above the distilling temperature of 360°C, accounted for more than half of the total mass of medium‐low‐temperature coal tar 17 . Compared with high‐temperature coal tar pitch, MLP had the characteristics of lower C/H, less quinoline insoluble matter, more heteroatoms (especially oxygen atoms), and lower aromatic condensation degree.…”