Influence of CePO4 with different crystalline phase on selective catalytic reduction of NO with ammonia

Integration of SiC Membrane and CePO4 Catalyst for the Simultaneous Efficient Removal of Dust and NO

“…Other samples had a broad NH 3 desorption peak at 50–600 °C. According to the previous work, the surface acid sites on CePO 4 are mainly provided by surface −OH, which are assigned as the Bronsted acid sites. , Therefore, the main NH 3 desorption peak of CePO 4 /SiC-X samples was observed at the temperature below 250 °C. Owing to their highest O–H ratio and largest specific surface area shown in BET and O 1s XPS results, the CePO 4 /SiC-400 catalytic membrane had the largest adsorption peak at 50–250 °C, indicating that the CePO 4 /SiC-400 catalytic membrane can provide more weak acid sites for the adsorption and activation of NH 3 . , …”

“…All samples were separated into four peaks consisting of Si−O, nonbridging oxygen (P−O), bridging oxygen (P−O−P), and hydroxyl oxygen (O−H). 36,37 According to the fitting results (Table S1), the lower loading of the CePO 4 catalyst led to a higher occupation of Si−O specific gravity. 36 The contents of hydroxyl oxygen (O−H) and nonbridging oxygen (P−O) increase and then reduce with increasing calcination temperature, whereas bridging oxygen (P−O−P) falls and then increases.…”

Catalytic Hydrolysis–Oxidation of Halogenated Methanes over Phase- and Defect-Engineered CePO4: Halogenated Byproduct-Free and Stable Elimination

“…This showed that the residual H 2 O was stable and not removed by the thermal treatment (before DCM was introduced, the sample was purged at 400 °C in 20 vol % O 2 /Ar for 1 h), while the presence of DCM facilitated the release of adsorbed or structurally bound water molecules through their adsorption onto surface hydroxyl groups. More importantly, the intensity of these bands exhibited a significant decrease in the order h-CePi > Lm-CePi > Hm-CePi, which was in alignment with the inherent characteristics of these CePO 4 catalysts because more abundant structural H 2 O or surface hydroxyls were found on h-CePi. − After the temperature increased to 200 °C, the singlet IR band at 1575 cm –1 was observed and ascribed to the carboxylate groups, besides the methyl group absorbance at 1360–1380 cm –1 , which indicated that the oxidative decomposition of DCM occurred. Figures d, S7, and S8 further display in situ DRIFTS of DCM decomposition in the presence of D 2 O.…”

“…For example, monoclinic phosphate exhibited superior peroxidase enzymatic activity due to a greater ability to create hydroxyl radicals . The presence of the channels containing water in hexagonal CePO 4 led to an enhancement of the water–gas shift reaction owing to the increasing interaction with the water molecules, while the additional formation of monodentate formate and carbonate species could block the active sites on monoclinic CePO 4 due to the lower surface water content. , Hexagonal CePO 4 showed better NH 3 –SCR denitration activity and stability than monoclinic CePO 4 , which was attributed to the much stronger surface acidity and more surface-adsorbed oxygen species on the former . Additionally, defect engineering is considered an excellent approach for tuning the physical and chemical properties due to the alteration in the material’s composition, structural orientation, disordering, and lattice strain; various and abundant intrinsic defects (depending on its pristine structure or they can be introduced intentionally via thermal treatment, pH modification, size narrowing, and phase transition) are located in CePO 4 , such as Ce Frenkel (12.41 eV) > O Frenkel (11.02 eV) > Ce vacancy (9.09 eV) > O vacancy (6.69 eV), and their formation energies follow this trend (given in the decreasing order of energy) …”

Revealing the influencing mechanism of CO2 on SCR of NOx with NH3 over FeW mixed oxide catalyst: interactions of carbonate-Fe2O3–FeWO4

“…With only the injection of NO + O 2 , the main ad-species are NO 2 adsorbed species (1606 cm À1 ) and v(NO 2 ) vibrational peak of nitrite species (1229 cm À1 ), which weakly adsorb on the catalyst surface. 26,27 After the addition of CO 2 , the adsorption peaks of the distinct adsorption species NO 2 species (1604 cm À1 ) and v(NO 2 ) of the nitrite species (1233 cm À1 ) have weakened, suggesting the presence of CO 2 is detrimental to NO 2 formation. Meanwhile, the former monodentate nitrate species (1431 cm À1 ) disappears.…”