Insights into the promotion role of phosphorus doping on carbon as a metal-free catalyst for low-temperature selective catalytic reduction of NO with NH₃

Abstract

P species can effectively enhance the catalytic activity of carbon aerogels for NO reduction at low temperature.

Promotion of Phosphorus on Carbon Supports for MnOx−CeO2 Catalysts in Low‐Temperature NH3−SCR with Enhanced SO2 Resistance

“…TPR profile of P‐CA also shows strong peaks at the temperature range of 400–600 °C. Our previous study indicated that C−O−P and C 3 −P=O groups are present on the surface of P‐CA, [22] and the reduction process of C−O‐P→C 3 ‐P=O→C 3 ‐P→elemental P can occur with the temperature rising in H 2 atmosphere, [40] resulting in a higher total H 2 consumption for P‐CA as shown in Figure 8b. In addition to the reduction of P‐containing functional groups at 300–700 °C, another possible reason for the shift of reduction peak to higher temperature of 10 %MnO x −CeO 2 /P‐CA compared with 10 %MnO x −CeO 2 /CA should be due to the intense interaction between MnO x and CeO 2 , mainly the reduction of the Mn‐O−Ce species occurs at this temperature range [39] …”

“…The band at 1162 cm −1 and 1130 cm −1 is assigned to bulk‐like sulfate and bidentate sulfate, respectively [54] . The peaks at 1040 and 920 cm −1 are attributed to the stretching motion of surface coordination of bisulfite that is generated from the reaction of SO 2 and surface hydroxyl groups, [52] and our previous study has shown that much hydroxyl groups are present on the P‐CA surface [22] . Figure 12b shows the in‐situ DRIFT spectra of SO 2 +O 2 adsorption on the 10 %MnO x −CeO 2 /CA catalyst [52] .…”

“…Consequently, the peaks below 300 °C are attributed to desorption of the NH 4 + ion from the Brønsted acid sites, and the peaks above 300 °C are assigned to desorption of NH 3 coordinated at the Lewis acid sites [11,21] . The NH 3 ‐TPD profile of P‐CA displays a stronger peak at 50–200 °C than CA, which should be attributed to the Brønsted acid sites originated from the C‐OH and P‐OH functional groups [22] . The NH 3 desorption peaks at 100–700 °C for 10 %MnO x −CeO 2 /CA catalyst is larger than that of CA, indicating the loading of MnO x −CeO 2 leads to the enhanced strength of Brønsted and Lewis acid sites.…”

“…Recently, we found that P doping on carbon can increase the Brønsted acidity and promote the NO 2 generation that are beneficial for the NH 3 −SCR reaction [22] . Moreover, it was reported that P modification can inhibit the thermal oxidation of carbon, [23,24] which is important for the practical applications of carbon‐supported catalysts.…”

Aqueous Phase Reforming over Platinum Catalysts on Doped Carbon Supports: Exploring Platinum–Heteroatom Interactions

“…Therefore, Pt/CNF-HT and Pt/N-CNF are less acidic catalysts compared to the other catalysts. Pt/P-CNF exhibited the highest desorption peak at 210 °C, most likely associated with P–OH, which is favorable for coordinating with NH 3 . Next in acidity, Pt/B-CNF has the highest desorption peak at 180 °C, including a shoulder at 255 °C, which may be related to oxidized boron species, as revealed by XPS analysis (Table S4).…”