Acid pretreatment of support promotes Pd/SiO2 activity for formaldehyde oxidation at room temperature

Abstract

Formaldehyde (HCHO) is a major pollutant in indoor air. The development of low-cost and high-efficiency technologies to remove HCHO at room temperature is thus of great importance. Here, we developed a simple method involving acid pretreatment of SiO₂ to improve a Pd/SiO₂(HNO₃)-R catalyst for HCHO oxidation. Multiple characterization results illustrated that the hydroxyl groups on SiO₂ produced by the acid pretreatment favored the anchoring of Pd particles and increased their dispersion. The increase in Pd dispersion induced more oxygen vacancies on the surface of the Pd/SiO₂(HNO₃)-R catalyst because of the increased number of hydrogen spillover sites; this further enhanced H₂O activation to form surface-active hydroxyl groups, thus significantly increasing the intrinsic activity of the Pd/SiO₂(HNO₃)-R catalyst for HCHO oxidation.