期刊
CATALYSTS
卷 11, 期 3, 页码 -出版社
MDPI
DOI: 10.3390/catal11030314
关键词
hierarchical SAPO-34; manganese oxides; low-temperature NH3-SCR; molecular sieves; SO2 resistance
资金
- National Natural Science Foundation of China [NSFC-51478191]
- Key Research and Development Plan of Guangdong Province [2019B110207001]
A series of MnOx/SAPO-34 catalysts were synthesized using the ethanol dispersion method, with SAPO-34 as the zeolite carrier with a hierarchical pore structure obtained through facile acid treatment. The NH3-SCR performance of these catalysts showed that MnOx/SAPO-34-0.1 catalyst with ca.15 wt.% Mn loading exhibited optimal catalytic activity and SO2 tolerance at low temperatures, achieving almost 100% NO conversion and over 90% N2 selectivity at 120 degrees C under GHSV of 40,000 h(-1).
The ethanol dispersion method was employed to synthesize a series of MnOx/SAPO-34 catalysts using SAPO-34 with the hierarchical pore structure as the zeolite carrier, which were prepared by facile acid treatment with citric acid. Physicochemical properties of catalysts were characterized by XRD, XPS, BET, TEM, NH3-TPD, SEM, FT-IR, Py-IR, H-2-TRP and TG/DTG. NH3-SCR performances of the hierarchical MnOx/SAPO-34 catalysts were evaluated at low temperatures. Results show that citric acid etching solution at a concentration of 0.1 mol/L yielded a hierarchical MnOx/SAPO-34-0.1 catalyst with ca.15 wt.% Mn loading, exhibiting optimal catalytic activity and SO2 tolerance at low temperatures. Almost 100% NO conversion and over 90% N-2 selectivity at 120 degrees C under a gas hourly space velocity (GHSV) of 40,000 h(-1) could be obtained over this sample. Furthermore, the NO conversion was still higher than 65% when 100 ppm SO2 was introduced to the reaction gas for 4 h. These could be primarily attributed to the large specific surface area, high surface acidity concentration and abundant chemisorbed oxygen species provided by the hierarchical pore structure, which could also increase the mass transfer of the reaction gas. This finding suggests that the NH3-SCR activity and SO2 poisoning tolerance of hierarchical MnOx/SAPO-34 catalysts at low temperatures can be improved by controlling the morphology of the catalysts, which might supply a rational strategy for the design and synthesis of Mn-based SCR catalysts.
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