title: Removal of formaldehyde over Mn(x)Ce(1)-(x)O(2) catalysts: thermal catalytic oxidation versus ozone catalytic oxidation.
abstract: Mn(x)Ce(1)-(x)O(2) (x: 0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO). At x=0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of CeO(2) to form a solid solution. The catalytic activity was best at x=0.5, at which the temperature of 100% removal rate is the lowest (270°C). The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5wt.% CuO(x) into Mn(0.5)Ce(0.5)O(2). With ozone catalytic oxidation, HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O₃over Mn(0.5)Ce(0.5)O(2) catalyst with a GHSV (gas hourly space velocity) of 10,000 hr⁻¹ at 25°C. The effect of the molar ratio of O(3) to HCHO was also investigated. As O(3)/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O(3)/HCHO ratio of 8, the mineralization efficiency of HCHO to CO(2) was 86.1%. At 25°C, the p-type oxide semiconductor (Mn(0.5)Ce(0.5)O(2)) exhibited an excellent ozone decomposition efficiency of 99.2%, which significantly exceeded that of n-type oxide semiconductors such as TiO(2), which had a low ozone decomposition efficiency (9.81%). At a GHSV of 10,000 hr⁻¹, [O(3)]/[HCHO]=3 and temperature of 25°C, a high HCHO removal efficiency (≥ 81.2%) was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chungli 32001, Taiwan, Chinese Taipei.
authors.forename: Jia Wei
authors.initials: JW
authors.lastname: Li
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chungli 32001, Taiwan, Chinese Taipei.
authors.forename: Kuan Lun
authors.initials: KL
authors.lastname: Pan
authors.affiliation: Industrial Technology Research Institute, Hsinchu 31040, Taiwan, Chinese Taipei.
authors.forename: Sheng Jen
authors.initials: SJ
authors.lastname: Yu
authors.affiliation: Industrial Technology Research Institute, Hsinchu 31040, Taiwan, Chinese Taipei.
authors.forename: Shaw Yi
authors.initials: SY
authors.lastname: Yan
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chungli 32001, Taiwan, Chinese Taipei. Electronic address: mbchang@ncuen.ncu.edu.tw.
authors.forename: Moo Been
authors.initials: MB
authors.lastname: Chang
mesh_terms: D016902:Air Pollution, Indoor / Q000517:prevention & control*; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry; D005557:Formaldehyde / Q000302:isolation & purification*; D006358:Hot Temperature; D017895:Manganese Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*
chemical_list: D017895:Manganese Compounds; C032786:cerium nitrate; D005557:Formaldehyde; D019343:Citric Acid; D002563:Cerium; D010126:Ozone
keywords: Formaldehyde; Indoor air pollutant; Ozone catalytic oxidation; Thermal catalytic oxidation; Volatile organic compounds