The effect of acid treatment on pyrolysis of Longkou oil shale

ABSTRACT

The effect of acid treatment on mineral removal and pyrolysis of Longkou oil shale were investigated. X-ray diffraction (XRD) and X-ray fluorescence (XRF) indicated that the HCl treatment can remove the calcite, the H₂SO₄ treatment can convert the calcite to CaSO₄, and the HF treatment can remove the quartz and convert the calcite to CaF₂; moreover, all three treatments cannot remove the pyrite in the oil shale. Oil shale was individually treated with HCl, H₂SO₄, and HF before conducted the pyrolysis experiment. The pyrolysis results showed that oil shale treated with H₂SO₄ or HF almost equally enhanced the oil yield, while HCl treatment had a negative effect on the oil yield. Thermogravimetry (TG) analysis indicated that the carbonates had a catalytic effect, sulfates may also had a catalytic effect and the silicates had an inhibitive effect on the decomposition of kerogen. Combining the TG analysis, oil yield and the price of every acid, the H₂SO₄ treatment was considered to be the best method to treat oil shale.Moreover, the carbonate minerals can be removed after H₂SO₄ treatment, so it would reduce the amount of pyrolysis feed to increase production efficiency.

KEYWORDS:

• Oil shale
• acid treatment
• pyrolysis
• oil yield
• oil/gas ratio

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51704300]; State Key Development Program of Basic Research of China [2014CB744301], and Yue Qi Distinguished Scholar Project, China University of Mining & Technology, Beijing.