In-plasma-catalysis for NOx degradation by Ti3+ self-doped TiO2−x/γ-Al2O3 catalyst and nonthermal plasma
In an attempt to realize the efficient treatment of NOx, a mixed catalyst of Ti3+ self-doped TiO2−x and γ-Al2O3 was constructed by reducing commercial TiO2. The degradation effect on NOx was evaluated by introducing the mixed catalyst into a coaxial dual-dielectric barrier reactor. It was found that the synthesized TiO2−x could achieve considerable degradation effects (84.84%, SIE = 401.27 J L−1) in a plasma catalytic system under oxygen-rich conditions, which were better than those of TiO2 (73.99%) or a single plasma degradation process (26.00%). The presence of Ti3+ and oxygen vacancies in TiO2−x resulted in a relatively narrow band gap, which contributed to catalyzing deeply the oxidation of NOx to NO2− and NO3− during the plasma-induced “pseudo-photocatalysis” process. Meanwhile, the TiO2−x showed an improved discharge current and promoted discharge efficiency, explaining its significant activation effect in the reaction. Reduced TiO2−x could achieve an impressive degradation effect in a long-time plasma-catalysis process, and still maintained its intrinsic crystal structure and morphology. This work provides a facile synthesis procedure for preparing Ti3+ self-doped TiO2−x with practical and scalable production potential; moreover, the novel combination with plasma also provides new insights into the low-temperature degradation of NOx.
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