Cerium-Based Catalytic Materials for Industrial Waste-Gas Purification: Current Status, Future Directions, and Mechanistic Insights

Nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide (SO2), and volatile organic compounds (VOCs) in industrial waste gases pose significant threats to environmental quality and human health. Catalytic purification is recognized as a leading abatement technology, crucial for meeting increasingly stringent emission regulations. Rare-earth (RE) catalytic materials, particularly those based on cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) oxides, have attracted intense research due to their unique electronic configurations, high oxygen storage capacity (OSC), facile reversible redox reactions Ce4+, Ce3+, and exceptional thermal stability. This paper provides a comprehensive and methodical overview of RE catalysts used in industrial waste-gas purification. Initially, the physicochemical characteristics of RE elements and their multifaceted roles as active phases, supports, and promoters are explained. Subsequently, the latest developments in RE-based catalysts for NOx abatement, CO oxidation, VOC degradation, and the removal of sulfur-bearing gas are critically reviewed. The discussion emphasizes structure–activity relationships, reaction mechanisms, and the synergistic interactions between RE elements and transition metals. Comparative analyses are presented through tables focusing on catalyst composition, reaction conditions, performance parameters, and stability. Special attention is given to the enhanced resistance to water vapor and sulfur poisoning afforded by RE materials. Finally, current challenges and future research prospects, including cost reduction, scalability, and long-term durability, are suggested. This review aims to provide practical guidance for the rational design and industrial translation of next-generation RE catalytic materials for air pollution control.