Reconstruction and recovery of anatase TiO2 from spent selective catalytic reduction catalyst by NaOH hydrothermal method

Abstract

The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste. A novel process to recover anatase titanium dioxide (TiO2) from spent SCR catalysts was proposed. The process included alkali (NaOH) hydrothermal treatment, sulfuric acid washing, and calcination. Anatase TiO2 in spent SCR catalyst was reconstructed by forming Na2Ti2O4(OH)2 nanosheet during NaOH hydrothermal treatment and H2Ti2O4(OH)2 during sulfuric acid washing. Anatase TiO2 was recovered by decomposing H2Ti2O4(OH)2 during calcination. The surface pore properties of the recovered anatase TiO2 were adequately improved, and its specific surface area (SSA) and pore volume (PV) were 85 m2·g−1 and 0.40 cm3·g−1, respectively. The elements affecting catalytic abilities (arsenic and sodium) were also removed. The SCR catalyst was resynthesized using the recovered TiO2 as raw material, and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst. This study realized the sustainable recycling of anatase TiO2 from spent SCR catalyst.