Characterization of Toluene Insolubles from Low‐Temperature Coal Tar

Abstract

Hydrogenation has been investigated in recent years as a potential method for upgrading low‐temperature coal tar (LCT). LCT contains toluene insolubles (TIs) that can cause process problems by plugging hydrotreater feed filters and catalyst beds. In this study, TIs are separated from LCT, and the composition and structure are studied by using elemental analysis, scanning electron microscopy (SEM), Fourier‐transform infrared spectrometry (FTIR), X‐ray diffraction analyses (XRD), X‐ray photoelectron spectroscopy (XPS), and other techniques. Microscopic observations reveal TI particles to be small approximately 50 % of the particles have a diameter of <3 μm. TIs contain a high proportion of inorganic material, for example, quartz, aluminosilicate, and calcium. Evidence for aliphatic and aromatic species is demonstrated by FTIR and XPS analysis. Although LCT contains many complex aromatic compounds, TIs exhibit a lower degree of aromaticity. Sulfate salts are the main form of sulfur element, and the greatest amounts of nitrogen occur in TIs as pyridinic nitrogen (N‐6) and oxidized nitrogen (N‐X) species.

Investigation on Asphaltenes Structures during Low Temperature Coal Tar Hydrotreatment under Various Reaction Temperatures

“…Compared with fossil fuels, LCT is an inferior oil due to its great density and high asphaltenes content. 32 The density of LCT is in the range of 0.97−1.04 g/cm 3 (20 °C), which is higher than that of traditional crude oil. 12 The oxygen content in LCT (6−8 wt %) is generally much higher than that in crude oil and other mineral oil (less than 2 wt %).…”

“…Compared with fossil fuels, LCT is an inferior oil due to its great density and high asphaltenes content . The density of LCT is in the range of 0.97–1.04 g/cm 3 (20 °C), which is higher than that of traditional crude oil .…”

Technical Progress and the Prospect of Low‐Rank Coal Pyrolysis in China

“…In March 2016, the National Development and ReformCommissionpromulgated the Energy Te chnology In-novationA ction Plan (2016-2030), for which mature technical processes for LRC pyrolysis and industrial demonstration projects( milliont ons) would be achieved in 2020. [11] Simultaneously,L RC pyrolysis technology (1 million tons) will be applied and recommended in China in 2030. [12,13] Thus,a chieving the grading effective conversion and utilization of LRC through pyrolysis technologies presentsabroad prospect in China.…”

“…In May 2015, the National Energy Board issued the Coal Clean and Efficient Use Plan of Action (2015–2020), which required promotion of the grading effective conversion and steady utilization of coal as well as the construction of demonstration projects in China with the highly effective use of clean coal. In March 2016, the National Development and Reform Commission promulgated the Energy Technology Innovation Action Plan (2016–2030), for which mature technical processes for LRC pyrolysis and industrial demonstration projects (million tons) would be achieved in 2020 . Simultaneously, LRC pyrolysis technology (1 million tons) will be applied and recommended in China in 2030 .…”