Spectroscopic Insights into the Mechanism of Selective Catalytic Reduction of NO by Ammonia on Sulfuric Acid‐modified Fe₂O₃ Surface

Abstract

Recently, we show that a novel architecture based on sulfuric acid‐modified Fe2O3 nanoplates provide highly efficient catalyst for selective catalytic reduction of NO by NH3. In the present article, it has been possible to identify the reaction mechanism and the nature of the surface active species in this catalyst by using time‐resolved diffuse reflectance infrared Fourier‐transform spectroscopy. The results suggest a catalytic cycle that involves surface NH4+ and NO2− species, which would be efficient as surface species in the (NH4+)(NO2−)→N2+2H2O conversion. Hence, a model for the abatement of NOx has been proposed, which accounts for the observed high activity and selectivity of the catalyst.

Adsorption of heavy metal onto biomass-derived activated carbon: review

“…[151][152][153][154] The functional groups on the surface of activated carbon are oxygen-containing functional groups, such as hydroxyl, carboxyl, carbonyl and lactone groups, which are introduced through the oxidation pathway. [155][156][157] The introduction of carboxyl groups on the surface of biomass-derived activated carbon will play an important role in the adsorption of metal ions. The hydrogen in the carboxyl group will be ionexchanged by metal ions, and the carboxyl group will chelate with metal ions.…”

Fe2O3/HY Catalyst: A Microporous Material with Zeolite-Type Framework Achieving Highly Improved Alkali Poisoning-Resistant Performance for Selective Reduction of NOx with NH3

“…Zeolite HY with excellent cation exchange ability is employed as a support and buffer zone to protect the active sites. Given the nontoxic, earth-abundant nature, and its capability to activate certain reactants, − Fe 2 O 3 is selected as the active surface phase of the catalyst for NH 3 –SCR reaction. The Pyridine infrared spectrometer (Py-IR) and H 2 -temperature-programmed reduction (H 2 -TPR) experiments reveal that the acid sites on the external surface and the reducibility of surface oxygen are preserved after 1000 μmol g –1 of Na + poisoning.…”

Alkali-Poisoning-Resistant Fe2O3/MoO3/TiO2 Catalyst for the Selective Reduction of NO by NH3: The Role of the MoO3 Safety Buffer in Protecting Surface Active Sites

“…In the present study, the TiO 2 -supported MoO 3 building block is used as a binding buffer to provide sufficiently stable binding sites for Na 2 SO 4 poison, which is present in plant exhaust, and to prevent alkali blocking of the surface active phase. Fe 2 O 3 is chosen as the surface active phase because of its low cost, nontoxic nature, and ability to promote the SCR reaction at medium temperatures. − The strong interaction between the Na + and the layered MoO 3 is revealed by X-ray diffraction (XRD). The changes in surface acid sites and the reducibility of the catalyst before and after Na 2 SO 4 poisoning treatment are visualized by site-specific probe molecule infrared (IR) spectroscopy with NH 3 and the H 2 -temperature-programmed reduction (H 2 -TPR) studies, respectively.…”