Visible-light-assisted efficient removal of sulfur from high sulfur coal under mild conditions

ABSTRACT

In order to find a green and effective chemical desulfurization method, the photocatalytic technology and oxidative desulfurization were combined to minimize the sulfur content in coals. In this paper, 30% H₂O₂ was mixed with raw coal, demineralized coal, and removal pyrite coal at a ratio of 5:1 (ml: g), the oxidative desulfurization reaction was carried out with visible light irradiation for different times, and compared with the experimental results without light irradiation under the same condition. IC was used to characterize the SO₄^2- content in the filtrate of the reaction mixture, and the chemical method was used to determine the forms of sulfur in coal samples before and after desulfurization, FTIR was used to characterize the change of sulfur-containing functional group content in coal samples before and after desulfurization. And the photochemical characterization of raw coal, demineralized coal and removal pyrite coal were carried out to explore the photochemical properties of different coal samples, further explored the reasons for the promoting effect of visible light irradiation on H₂O₂ oxidation desulfurization. The experimental results showed that the desulfurization efficiency can be significantly enhanced by visible light irradiation. Under the optimum conditions, the desulfurization rate can reach 67.68%, most of the pyrite and part of organic sulfur in coals were effectively removed. The pyrite in coal was the main reason for the promotion of H₂O₂ oxidative desulfurization by visible light irradiation.

KEYWORDS:

• Photocatalysis
• oxidation desulfurization
• forms of sulfur
• FeS₂
• light response

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [21666001] and the Ningxia Natural Science Foundation [2020AAC03208].