Low-Cost CuX Catalyst from Blast Furnace Slag Waste for Low-Temperature NH₃-SCR: Nature of Cu Active Sites and Influence of SO₂/H₂O

Abstract

A series of Cu-exchanged zeolite NaX (derived from blast furnace slag) catalysts were synthesized by an ionexchanged method. The low-temperature catalytic activity and SO 2 or/and H 2 O resistance of the catalysts were studied as well. The results found that the Cu(N)X catalyst exhibited excellent lowtemperature selective catalytic reduction (SCR) activity, whose NO conversion was nearly 100% at ca. 175 °C and remained stable, while the Cu(C)X catalyst showed the poorest catalytic performance. When SO 2 and H 2 O was introduced, the NO conversion of the Cu(N)X catalyst declined from 100% to 60%, and it could recover to ca. 63% after cutting off SO 2 and H 2 O. More isolated Cu 2+ species and surface chemisorbed oxygen species on the Cu(N)X catalyst could provide more active sites for SCR reaction, and more surface oxygen vacancies accelerated the oxidation of absorbed NH 3 species and NO species. Besides, the higher surface acidity and redox ability on the Cu(N)X catalyst promoted the SCR reaction performance. In addition, after the poisoning of SO 2 /H 2 O, the surface acidity decreased, redox ability became poor, and the Cu active species was less than that of the Cu(N)X catalyst, indicating that the Cu active sites were consumed during the reaction. Furthermore, it could also be found that the generated sulfate species occupied the main active sites and reduced the varieties of nitrate species and intermediates, thereby reducing the SCR activity of the catalyst. KEYWORDS: low-temperature NH 3 -SCR, blast furnace slag, zeolite NaX, Cu 2+ active sites, SO 2 /H 2 O influence

Low-Dose Element-Doped CeCrM/TiO2 (M = La, Cu, Fe, LaCu, LaFe) Catalyst for Low-Temperature NH3-SCR Process: Synergistic Effect of LaCu/LaFe

“…The types of salt species and intermediates lead to bad NH 3 -SCR activity. 34 In this study, it can be known from XPS that after adding La (CeCrLaCu/TiO 2 ), Cu 2+ decreases and Cu+ increases, so it can reduce the formation of sulfate with sulfuric acid, thereby inhibiting poisoning. Hydrothermal stability refers to the property of catalytic cracking catalysts in industrial application.…”

“…For example, the metal element Cu easily reacts with sulfuric acid generated by H 2 O and SO 2 , resulting in the lack of active components and additives, and the sulfate species generated on the surface of the catalyst consumes the active Cu 2+ species and occupies the main active sites, thereby reducing nitric acid. The types of salt species and intermediates lead to bad NH 3 -SCR activity . In this study, it can be known from XPS that after adding La (CeCrLaCu/TiO 2 ), Cu 2+ decreases and Cu+ increases, so it can reduce the formation of sulfate with sulfuric acid, thereby inhibiting poisoning.…”

Metallurgical slag used for efficient growth of Chlorella pyrenoidosa to achieve CO2 conversion to biodiesel

“…On this basis, a series of copper exchange zeolite NaX catalysts using blast furnace slag (BFS) as raw material were prepared by ion exchange method, the results showed that Cu(N)X catalyst exhibited excellent low temperature selective catalytic reduction activity, and the NO conversion rate was close to 100% at 175°C and remained stable. [4,5] Ren et al proposed an indirect CO 2 storage method using blast-furnace slag as raw material, and the results showed that the net CO 2 emissions could be reduced by 36 kg for every 1000 kg of blast-furnace slag treated. [6] Metallurgical slag has obtained good results in terms of catalyst and carbon capture.…”

Enhanced Catalytic Activity of Pd Supported on TiO2 Nanowire for the H2-SCR of NOx in the Presence of Oxygen

“…Nitrogen oxides (NO x ) are mainly emitted from automobile exhaust gas and flue gas of industrial combustion of fossil fuels and can cause photochemical smog, acid rain, ozone depletion, and greenhouse effects, thus leading to hazardous effect on the environment and human health. − Several promising catalytic technologies, such as NO x storage and reduction (NSR) and selective catalytic reduction (SCR) of NO x , have been developed to reduce NO x emissions. − Among them, selective catalytic reduction of NO x by NH 3 is the most widely used technology . However, this approach comes with issues such as NH 3 slip and “white powder” formation, which limits its practical application. − Therefore, research has also focused on the development of new technology or using alternative reductants to remove NO x by the SCR process.…”