## 1 Introduction  
As one of the most toxic and complicated kinds of volatile organic compounds (VOCs), chlorinated volatile organic compounds (CVOCs) are usually difficult to eliminate [1, 2] due to their high volatility, strong recalcitrance, and their side effects for the operation system [3, 4, 5]. CVOCs includes chlorinated alkanes [6, 7], chlorinated olefins [8], chlorinated aromatic hydrocarbons [9], etc., which are regarded as vital compounds of common contaminants, which have been widely investigated for years [10, 11]. Adsorption [12, 13, 14], absorption, condensation and thermal incineration [15], biodegradation [16], photocatalytic degradation [17], plasma technology, and catalytic combustion [4] are applied for elimination of these pollutants. Of which, catalytic oxidation is widely considered as one of the most promising method due to ultra-purification efficiency, few secondary pollution, and lower reaction temperature; therefore it is thought to be one of the most impressive methods for CVOCs elimination. Currently, the catalysts for CVOC catalytic oxidation can be mainly applied to supported noble metals, molecular sieves, transition metal oxides, perovskite catalysts, etc. Among these different materials, noble metal-based catalysts have, in recent years, received the attention of many researchers due to their superior low-temperature activity, high CO\({}_{2}\) selectivity, and competitive stability. More importantly, noble metal-based catalysts have been successfully applied practically in various heterogeneous catalytic areas. Few other kinds of materials can be substituted for noble metals in practical operation nowadays [2]. Supported noble metal catalysts are generally catalysts with ruthenium (Ru) [18], platinum (Pt) [19], palladium (Pd) [20], or rhodium (Rh) [21] as active components, and inactive oxides (such as Al\({}_{2}\)O\({}_{3}\)[22; 23], SiO\({}_{2}\), ZrO\({}_{2}\)[24], TiO\({}_{2}\)[25; 26], etc. ), molecular sieves [27], perovskite composite oxide LaBO\({}_{3}\)[28; 29], and pillared clay as carriers. [PERSON] et al. [23] proposed a bifunctional reaction mechanism of dichloromethane catalyzed by Pt/Al\({}_{2}\)O\({}_{3}\), that is, CH\({}_{2}\)Cl\({}_{2}\) disproportionated on Al\({}_{2}\)O\({}_{3}\) to form CH\({}_{3}\)Cl and CO, and then further oxidized on the active site of the Pt metal species. [PERSON] et al. [30] believe that the catalytic activity of the catalyst increases with the noble metal loading amount, and the results showed that a Pt/CeO\({}_{2}\)-ZrO\({}_{2}\) catalyst with 1% Pt loading is the best. [PERSON] et al. [31] synthesized an H-Beta-supported Pd material for TCE elimination, and the results showed that the 50% conversion of the TCE reaction temperature shifted forward by 150 \({}^{\circ}\)C for the molecular sieve supported by precious metal, and PdO was the main active phase, and its activity and stability were better than that of precious metal Pd. At the same time, PdO/H-Beta improves the selectivity of CO\({}_{2}\), but also increases the production of chlorine. [PERSON] et al. [32] studied the catalytic decomposition of chlorobenzene over Pd/ZrO\({}_{2}\) and Pd/TiO\({}_{2}\) materials. It was found that, because TiO\({}_{2}\) has higher reducibility than ZrO\({}_{2}\), the Pd/TiO\({}_{2}\) catalyst has better activity, and both catalysts produce a large amount of polychlorinated benzene. In the same year, they found that [33] there was a synergistic effect between the metal Pd and perovskite, which made the catalytic efficiency of Pd/LaBO\({}_{3}\) better than that of pure perovskite. [PERSON] et al. [34] prepared the supported Ru/CeO\({}_{2}\) catalyst and found that the dichloromethane effect from catalyst surface was promoted due to superior deacon reaction activity of RuO\({}_{2}\), which is beneficial for active sites protection and catalyst stability. Based on the results, the author prepared a series of Ru/Ti-CeO\({}_{2}\)[35] catalysts by doping Ti, and found that the superior combination of 5% Ti doping showed the best reaction performance.