Pyrolysis behavior and pyrolysate characteristics of Huadian oil shale kerogen catalyzed by nickel-modified montmorillonite

Given the abundance of clay minerals in oil shales, the in-situ cracking of oil shale is preferably enhanced by catalysis, such as by modifying reservoir clays with soluble catalytically active materials. In this work, nickel-modified montmorillonite was synthesized via a simple method, and the feasibility of in-situ catalytic cracking of oil shales to facilitate engineering implementation was investigated. Thermogravimetric analysis was performed to assess the impact of the catalyst on the pyrolysis behavior of kerogen. The results demonstrated that nickel-modified montmorillonite effectively reduces the initial cracking temperature of kerogen and enhances the hydrocarbon generation rate. The results of thermogravimetric-Fourier transform infrared spectrum and thermogravimetric-mass spectrometry analysis revealed a significant boost in the production of smaller molecules and non-condensable gases, including hydrogen, methane, ethane, and benzene. Concurrently, there was a notable reduction in carbon dioxide and sulfur dioxide emissions. Pyrolysis experiments were conducted to provide additional evidence of the effectiveness of nickel-modified montmorillonite, confirmed by a decrease in semi-coke production and a notable 11.25% increase in oil yield. Furthermore, the composition analysis of shale oil indicated an increased production of alkenes and aromatic hydrocarbons. These findings suggest that the addition of nickel-modified montmorillonite effectively enhances the depolymerization, deoxygenation and aromatization reaction, resulting in the formation of valuable products during the pyrolysis of oil shale kerogen. This study offers a promising avenue of cost-effective and efficient in-situ oil shale exploitation.