Modified porous ceramic catalysts derived from titanium-bearing blast furnace slag for efficient toluene oxidation

Titanium-bearing blast furnace slag (TBBFS) is a solid waste generated by the iron and steel industry, rich in valuable components such as TiO₂, SiO₂, Al₂O₃, and CaO. Conventional utilization methods mainly involve low-value applications or direct landfill disposal, leading to resource waste and potential environmental risks. In this study, TBBFS was innovatively employed to construct a porous ceramic catalyst support (TC). By regulating sintering temperature, holding time, and pore-forming agent content, a synergistic optimization between porosity and mechanical strength was achieved. After acid leaching, Cu, Ce, and Mn oxides were sequentially loaded onto the support through a stepwise hydrothermal method to prepare a series of hierarchical porous ceramic catalysts. The samples were systematically characterized by XRD, SEM, EDS, BET, and H₂-TPR analyses. The results show that the raw TBBFS catalyst exhibited negligible activity, with toluene conversion remaining below 10% within the tested temperature range. The acid-leached ceramic support (HNO₃@TC) achieved a T₅₀ of 411.6 °C but failed to reach T₉₀. For the single-metal catalyst Cu@TC, the T₅₀ and T₉₀ were 403.9 °C and 499.1 °C, respectively. The bimetallic Cu-Ce@TC achieved T₅₀ and T₉₀ at 345.4 °C and 469.3 °C, respectively. Compared with the raw TBBFS and the single- or bimetallic catalysts, the ternary Cu-Ce-Mn@TC catalyst exhibited outstanding performance, with T₅₀ and T₉₀ reaching 285.6 °C and 396.4 °C, respectively, fully demonstrating the remarkable enhancement of catalytic activity due to the synergistic effect among multiple metals. Furthermore, even under high space velocity (150,000 mL g⁻¹ h⁻¹) and high toluene concentration (3000 ppm), the Cu-Ce-Mn@TC catalyst maintained high activity and stability. During a continuous 36 h reaction test, toluene conversion was consistently maintained between 97 and 100% with minimal deactivation, highlighting its excellent efficiency, durability, and adaptability under complex operating conditions. In addition, kinetic fitting based on the Mars-van Krevelen (MVK) model revealed that the catalytic oxidation followed a lattice oxygen participation mechanism, with the oxidation step identified as the rate-determining step. Therefore, this study demonstrates the efficient application of TBBFS-derived ceramic supports in VOCs abatement, not only expanding the resource utilization pathway of metallurgical solid waste but also providing a new technical route and theoretical foundation for the development of low-cost, efficient, and environmentally friendly catalyst systems.