Supercritical water synthesized Ni/ZrO2 catalyst and its application in the harmless treatment of oilfield wastewater in supercritical water

• Published in: Journal of environmental chemical engineering 2024-10, Vol.12 (5), p.113989, Article 113989
• Main Authors: Kou, Jiajing, He, Zigan, Wang, Gaoyun, Lu, Libo, Wei, Wenwen
• Format: Article
• Language: English
• Subjects: Harmless treatment; Ni/ZrO2 catalyst; Oilfield wastewater; Supercritical water gasification; Supercritical water synthesis
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.113989

Supercritical water (SCW) catalytic gasification is a clean and efficient technology with prominent advantages in treating oily wastewater generated in oilfields. SCW synthesis is a promising one-step preparation method for nano-catalytic materials, while the influence of organic matter on SCW synthesis materials remains to be studied. This study focuses on the synthesis of the Ni/ZrO2 catalysts by the supercritical water synthesis (SCWS) method, particularly examining how different types and concentrations of organic matter affect the catalysts’ pore information and structural characteristics. It found that glycerol acted as a more effective precursor for generating reducing gases compared to glucose. This is attributed to glycerol’s capacity in SCW to generate reducing gases for activating a greater number of Ni site within the catalyst, and the 5 wt% glycerol should be a proper concentration for SCWS of Ni/ZrO2. When employed in SCW treatment of oilfield wastewater, the Ni/ZrO2 catalyst demonstrated impressive results, achieving the carbon gasification efficiency of 99.1 % and a chemical oxygen demand (COD) removal efficiency of 100 % at 500°C. These findings indicate that the SCW technique can effectively and harmlessly treat oilfield wastewater using the Ni/ZrO2 catalyst under relatively mild conditions, showing its potential as an innovative solution for wastewater management in the oil industry. [Display omitted] •The Ni/ZrO2 catalysts were prepared by supercritical water (SCW) synthesis.•The effects of organics during catalyst SCW preparation were studied.•The Ni/ZrO2 showed good performance in SCW treatment of oilfield wastewater.•The COD removal efficiency achieved 100 % at 500°C in SCW.