Abstract

Lighter tars are largely useful in chemical industries but their quantity is quite little. Catalytic cracking is applied to improve the yield of light tars during pyrolysis. Consequently, in situ upgrading technique through a MoS2 catalyst has been explored in this research work. MoS2 catalyst is useful for the conversion of high energy cost into low energy cost. The variations in coal pyrolysis tar without and with catalyst were determined. Meanwhile, the obtained tar was analyzed using simulated distillation gas chromatograph and Elemental Analyzer. Consequently, the catalyst reduced the pitch contents and increased the fraction of light tar from 50 to 60 wt.% in coal pyrolysis tar. MoS2 catalyst increased the liquid yield from 18 to 33 (wt.%, db) and decreased gas yield from 27 to 12 (wt.%, db) compared to coal without catalyst. Moreover, it increased H content and hydrogen-to-carbon ratio by 7.9 and 3.3%, respectively, and reduced the contents of nitrogen, sulphur, and oxygen elements by 8.1%, 15.2%, and 23.9%, respectively, in their produced tars compared to coal without catalyst.

Highlights

  • Coal is heterogeneously complex structure having organic and inorganic macromolecules

  • The thermal cracking of tar generally occurs at high temperature through appropriate energy supply and reaction time which leads to decreasing the energy efficiency and tar yield

  • It determined the suitable temperature that led to the maximum tar yield

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Summary

Introduction

Coal is heterogeneously complex structure having organic and inorganic macromolecules. Low-rank coals have great importance in utilization but have some problems due to low efficiency and higher CO2 emissions compared to highrank coals. These coals are difficult for storage and transportation and are not suitable for direct combustion [1,2,3,4,5]. A coal tar in bulk quantity is produced during pyrolysis, but it contains high range of heavy organic components having boiling point greater than 360∘C called pitch. High valuable tar can be achieved to crack high range organic heavy components into desired components having boiling point less than 360∘C. The catalytic coal pyrolysis is the most promising technique to upgrade the coal pyrolysis tar under moderate conditions and increase the energy efficiency of industrial equipment [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]

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