NO_x Reduction over Smart Catalysts with Self-Created Targeted Antipoisoning Sites

Abstract

Selective catalytic reduction of NO x in the presence of alkali (earth) metals and heavy metals is still a challenge due to the easy deactivation of catalysts. Herein, NO x reduction over smart catalysts with self-created targeted antipoisoning sites is originally demonstrated. The smart catalyst consisted of TiO2 pillared montmorillonite with abundant cation exchange sites to anchor poisoning substances and active components to catalyze NO x into N2. It was not deactivated during the NO x reduction process in the presence of alkali (earth) metals and heavy metals. The enhanced surface acidity, reducible active species, and active chemisorbed oxygen species of the smart catalyst accounted for the remarkable NO x reduction efficiency. More importantly, the self-created targeted antipoisoning sites expressed specific anchoring effects on poisoning substances and protected the active components from poisoning. It was demonstrated that the tetrahedrally coordinated aluminum species of the smart catalyst mainly acted as self-created targeted antipoisoning sites to stabilize the poisoning substances into the interlayers of montmorillonite. This work paves a new way for efficient reduction of NO x from the complex flue gas in practical applications.

Boosting Water-Resistance Ability on a PTFE Modified Ti-OMS-2 Catalyst for Low-Temperature NH3-SCR Reaction

“…The results showed that NO + O 2 was adsorbed on the surface of the catalyst with different forms of nitrates, and the monodentate nitrate and bridged nitrate reached adsorption saturation. As shown in Figure b, it was obvious that the monodentate nitrate species (1433 cm –1 ) disappeared at 150 °C, whereas the bidentate nitrate (1310 cm –1 ) band increased with elevated temperature . The adsorption peak at 1310 cm –1 was slightly weaker and shifted to a higher wave number.…”

“…As shown in Figure 11a, only chelating nitrite (1270 cm −1 ) and monodentate nitrate (1433 cm −1 ) could be detected on the surface of the Ti-OMS-2-20%-PTFE catalyst in the first 9 min. 60 With the extension of adsorption time, the peak at 1270 cm −1 shifted to 1242 cm −1 . 61,62 It indicated that chelating nitrite was unstable and finally changed into bridged nitrate.…”

“…As shown in Figure 11b, it was obvious that the monodentate nitrate species (1433 cm −1 ) disappeared at 150 °C, whereas the bidentate nitrate (1310 cm −1 ) band increased with elevated temperature. 60 The adsorption peak at 1310 cm −1 was slightly weaker and shifted to a higher wave number. In addition, the bridged nitrite (1530, 1550 cm −1 ) and trans-(N 2 O 2 ) 2− (1078 cm −1 ) were detected.…”

“…With the extension of adsorption time, the peak at 1270 cm –1 shifted to 1242 cm –1 . , It indicated that chelating nitrite was unstable and finally changed into bridged nitrate. The bands at 1433, 1310, and 1615 cm –1 were assigned to monodentate nitrate, bridged nitrate, − and gaseous NO 2 molecules, respectively. The bands gradually became stronger over time.…”

Efficient NOx Reduction against Alkali Poisoning over a Self-Protection Armor by Fabricating Surface Ce2(SO4)3 Species: Comparison to Commercial Vanadia Catalysts

“…Selective catalytic reduction of NO x with ammonia (NH 3 -SCR) is considered an effective method to remove NO x . Herein, V 2 O 5 -WO 3 /TiO 2 catalysts have been commercially used for industrial and mobile sources. − Currently, in addition to the toxicity of vanadium, SCR catalysts face considerable deactivation by alkali metals in the flue gas in practical applications, especially for alkali-rich stack gases such as power plants fueled by biomass. − It has been observed that the physical poisoning of alkali metals on vanadia-based catalysts blocks the pore structures and harshly affects reactant diffusion. Conversely, chemical poisoning is caused by the reduction of Brønsted acidity. , …”