Amorphous and homogeneously Zr-doped MnOx with enhanced acid and redox properties for catalytic oxidation of 1,2-Dichloroethane

Pt and Mo Co-Decorated MnO2 Nanorods with Superior Resistance to H2O, Sintering, and HCl for Catalytic Oxidation of Chlorobenzene

“…H 2 -TPR and O 2 -TPD were employed to further confirm redox ability and determine possible oxygen species (Figure ), H 2 consumption and quantitative analysis of surface oxygen species are listed in SI Tables S1 and S3. The pristine MnO 2 (110Mn) featured by two overlapping reduction peaks centered at about 306 °C and indicated the reduction of MnO 2 to Mn 2 O 3 and Mn 2 O 3 to MnO without the formation of intermediate Mn 3 O 4 , moreover, H 2 consumption (10.2 mmol/g) also was in good agreement with the theoretical value for complete reduction of MnO 2 to MnO (11.5 mmol/g). The loading of Pt caused a low-temperature shift to 243 °C (Pt-110Mn), while Mo made MnO 2 more difficult to reduce (Mo-110Mn, 359 °C), which was consistent with Raman results.…”

“…After Pt or Mo was supported, the decreased intensity implied the incorporation of Pt or Mo into the tunnel structure, and the different shifts of Raman wavenumber was an indication of different reducibility for these Mn-based catalysts. The quantitative analysis about the Mn–O band force based on Hooke’s law was implemented, and showed the Mn–O band force constant (k) of Pt-110Mn reduced from 284.7 kN/m of 110Mn to 276.6 kN/m, whereas it increased to 294.6 kN/m (Mo-110Mn) with the addition of Mo (Figure B), which meant the possible formation of Pt–O–Mn structure weakening the surface lattice oxygen and Mo–O–Mn stabilizing surface lattice oxygen of MnO 2 . The former improved the reducibility of MnO 2 , while the latter enhanced its thermal stability, which was consistent with XRD and TG results.…”

“…5 After Pt or Mo was supported, the decreased intensity implied the incorporation of Pt or Mo into the tunnel structure, 25 and the different shifts of Raman wavenumber was an indication of different reducibility for these Mn-based catalysts. The quantitative analysis about the Mn−O band force based on Hooke's law was implemented, 14 expectedly led to a moderate stability and redox ability (k value was 280.2 kN/m). Moreover, the intensity ratio of Raman bands at 570 and 635 cm −1 (I 570 /I 635 ) was considered to be an indication of evaluating active lattice oxygen species (the O− Mn−O−Mn-O chains of octahedral MnO 6 ) and decreased in the following order: Pt-110Mn (1.5) > MoPt-110Mn (1.1) > 110Mn (0.54) > Mo-110Mn (0.37).…”

“…11,12 The introduction of Ti, Sn, and Zr led to the formation of more Lewis and Brønsted acid sites besides the enhancement of the redox ability, which presented a superior catalytic activity, durability, and selectivity of polychlorinated byproducts owing to the synergetic effect between acid and redox sites. 9,13,14 However, some issues about catalytic oxidation of Cl-VOCs over Mn-based catalysts such as durability and selectivity of polychlorinated byproducts still need to be further discussed. Additionally, it was also known that traditional VOCs such as benzene, toluene, and o-xylene (named as BTX) usually coappeared in the actual industrial emissions with various Cl-VOCs; thus, the versatile Mn-based catalysts were particularly desired.…”

“…Generally, various modification strategies such as the controlled fabrication of different crystal phases and planes, , bulk doping, and surface decoration, could be adopted to further optimize its catalytic performance. , Recent reports suggested that crystal phases of MnO x displayed a distinct difference in catalytic oxidation of Cl-VOCs owing to different surface oxygen vacancies, but the exposed planes were not further discussed . The doping of Fe and Ce improved the reducibility of MnO x and the mobility of oxygen, which evidently promoted the oxidation of Cl-VOCs, but the stability and selectivity need to be further improved. , The introduction of Ti, Sn, and Zr led to the formation of more Lewis and Brønsted acid sites besides the enhancement of the redox ability, which presented a superior catalytic activity, durability, and selectivity of polychlorinated byproducts owing to the synergetic effect between acid and redox sites. ,, However, some issues about catalytic oxidation of Cl-VOCs over Mn-based catalysts such as durability and selectivity of polychlorinated byproducts still need to be further discussed. Additionally, it was also known that traditional VOCs such as benzene, toluene, and o-xylene (named as BTX) usually coappeared in the actual industrial emissions with various Cl-VOCs; thus, the versatile Mn-based catalysts were particularly desired.…”