Controlled synthesis of niobium and rare earth mixed oxides for catalytic combustion of chlorinated VOCs in the synthesis process of polyether polyol and polyurethane

• Published in: Journal of solid state chemistry 2022-09, Vol.313, p.123318, Article 123318
• Main Authors: Jin, Yinying, Quan, Yiyao, Liu, Jiang, Qi, Chenze, Pan, Pengju, Shan, Bofang, Luo, Hong, Yang, Peng
• Format: Article
• Language: English
• Subjects: Catalytic combustion; Chlorinated VOCs; Mixed oxide; Nb2O5; Oxygen-rich CeNbO4+δ; Rare earth
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2022.123318

Catalytic technique is an effective and economical method to deal with air pollution. This work investigated the effect of recombination of rare earth (RE = Y, La, Ce, Pr and Nd) and Nb element, different calcination temperature and preparation methods on the physical/chemical properties of RENbO4+δ mixed oxides. These materials were used for catalytic combustion of chlorinated VOCs (using monochlorobenzene and 1,2-dichloroethane as representative examples), and the structure-performance relationship was explored. The results showed that the optimal catalyst was the oxygen-rich Ce–Nb–O mixed oxide. It was gradually sintered above 700 oC to form CeNbO4+δ compound, and its apparent catalytic activity decreased with the increase of calcination temperature. The high dispersion of Nb2O5 into CeO2 matrix lead to strong interaction between Ce, Nb and O elements, and thus more active oxygen species were obtained, which was beneficial to improving redox property and catalytic performance of catalyst. The apparent catalytic activity decreased in the order of CeNbO-hp (homogeneous precipitation of urea)＞CeNbO-cp (co-precipitation of (NH4)2CO3)＞CeNbO-sg (citric acid based sol-gel method)＞CeNbO-mm (simple mechanical mixing of Nb2O5 and CeO2)＞pure Nb2O5, CeO2. In the continuous reaction of 100 h, both monochlorobenzene and 1,2-dichloroethane could be completely destroyed at 320 oC to form HCl, CO2 and H2O on the optimized CeNbO-hp. [Display omitted] •Oxygen-rich Nb2O5 based rare earth mixed oxides were prepared.•CeO2–Nb2O5 displayed high catalytic performance for VOCs degradation.•Synergistic catalytic effect existed between CeO2 and Nb2O5.•CeO2–Nb2O5 showed good thermal stability and durability.