HCl-Tolerant HxPO₄/RuOx–CeO₂ Catalysts for Extremely Efficient Catalytic Elimination of Chlorinated VOCs

Bulk metal doping and surface phosphate modification were synergically adopted in a rational design to upgrade the CeO 2 catalyst, which is highly active but easily deactivated for the catalytic oxidation of chlorinated volatile organic compounds (Cl-VOCs). The metal doping increased the redox ability and defect sites of CeO 2, which mostly promoted catalytic activity and inhibited the formation of dechlorinated byproducts but generated polychlorinated byproducts. The subsequent surface modification of the metal-doped CeO 2 catalysts with nonmetallic phosphate completely suppressed the formation of polychlorinated byproducts and, more importantly, enhanced the stability of the surface structure by forming a chainmail layer. A highly active, durable, and selective catalyst of phosphate-functionalized RuO x –CeO 2 was the most promising among all the metal-doped (Ru, Pd, Pt, Cr, Mn, Fe, Co, and Cu) CeO 2 catalysts investigated owing to the prominent chemical stability of RuO x and its superior versatility in the catalytic oxidation of different kinds of Cl-VOCs and other typical pollutants, including dimethyl sulfide, CO, and C 3 H 8 . Moreover, the chemical stability of the catalyst, including its bulk and surface structural stability, was investigated by combining intensive treatment with HCl/H 2 O or HCl with subsequent ex situ ultraviolet–visible light Raman spectroscopy and confirmed the superior resistance to Cl poisoning of the phosphate-functionalized RuO x –CeO 2 . This work exemplifies a promising strategy for developing ideal catalysts for the removal of Cl-VOCs and provides a catalyst with the superior catalytic performance in Cl-VOC oxidation to date.