The design of Na, Cu and Mn co-doped amorphous aluminum catalyst for efficient chlorobenzene degradation with the assistance of non-thermal plasma

To address the issues of low activity and poor stability of manganese-based catalysts in the catalytic degradation of refractory volatile organic compounds such as chlorobenzene (CB), this study designed a sodium-doped Mn-Cu bimetallic catalyst supported on hydroxyl-rich pseudo-boehmite (PB), denoted as Na-CuMnO x /PB, depending on the route of “support hydroxylation, bimetallic synergy, and alkali metal modification”. The catalyst achieved highly efficient degradation of CB under room temperature with the non-thermal plasma assistance. The PB support significantly increased surface hydroxyl groups and acidity. MnO x /PB showed a degradation efficiency of 85.14 %, superior to the 73.98 % achieved by a conventional Al 2 O 3 -supported catalyst. Cu doping promoted the formation of a Mn-Cu synergistic structure, increasing the surface-adsorbed oxygen to 56.59 % and the Mn(IV)/Mn(III) ratio to 0.63, thereby improving the degradation efficiency to 92.02 %. However, chlorine deposition (Cl content: 3.91 %) caused rapid deactivation. After Na modification, the Na-CuMnO x /PB catalyst exhibited a further increased Mn(IV)/Mn(III) ratio of 0.79, enhanced weak basic and acidic sites. The abundant surface hydroxyl groups and alkaline sodium hydrolysis facilitated HCl generation, achieving an HCl selectivity of 40.95 % with surface chlorine deposition as low as 0.59 %, thereby enabling the catalyst to maintain a degradation efficiency of 95.95 % over 16 h. Mechanism studies revealed the crucial roles of acid-base sites, reactive oxygen species, and metal valence states in CB degradation. The bimetallic system promotes the redox cycling between Cu(II)/Cu(I) and Mn(IV)/Mn(III), enabling continuous regeneration of active species. This work provides new insights for designing highly active and chlorine-tolerant catalysts for low-temperature purification of chlorine-containing VOCs.