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The optimization of hydrothermal synthesis of Mn x Co 3‐x O 4 / GC catalyst for low temperature NH 3 ‐SCR /using design of experiments
Author(s) -
Ko Songjin,
Tang Xiaolong,
Gao Fengyu,
Zhou Yuansong,
Zhang Runcao,
Liu Yuanyuan,
Liu Hengheng
Publication year - 2021
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6854
Subject(s) - catalysis , calcination , fourier transform infrared spectroscopy , chemistry , scanning electron microscope , nuclear chemistry , analytical chemistry (journal) , temperature programmed reduction , urea , infrared spectroscopy , materials science , inorganic chemistry , chemical engineering , organic chemistry , engineering , composite material
BACKGROUND In this study, a new catalyst for low‐temperature selective catalytic reduction of NO x with NH 3 (NH 3 ‐SCR) were prepared by using glucose and discussed optimization of the synthetic conditions of Mn x Co 3−x O 4 /GC (glucose carbon) catalysts by using the design of the experiments. A response surface methodology (RSM) combined with the central composite design (CCD) was applied to model and optimize the synthetic conditions. RESULTS As a result, the optimum NO x conversion of 95.6% and N 2 selectivity of 81.8% were obtained at Mn/Co 2.1, urea/(Mn + Co) mole ratio 11.5, glucose/(Mn + Co) mole ratio 8.9, preparation temperature 175.4 ° C , and calcination temperature 376.3 ° C . The SEM (Scanning electron microscope) image and EDS (Energy Dispersive Spectroscopy) analysis showed that metal oxides of Mn and Co were uniformly accumulated on the carbon microsphere surface. XRD (X‐ray diffraction) patterns showed that CoCo 2 O 4 content in the catalyst increased with the increase of the glucose/(Mn + Co) mole ratio, which reduced the interaction between Mn and Co, and played a negative impact on catalytic performance. FTIR (Fourier‐transform infrared) spectra showed that the catalyst surface in the optimum preparation conditions had more oxygen‐containing functional groups and that the excessive glucose carbon was unfavourable to catalytic performance. For urea/(Mn + Co), as urea/(Mn + Co) decreased, in addition to the decrease in Mn and Co content in the catalyst due to the decrease in precipitant, CoCo 2 O 4 content in the catalyst also increased and oxygen‐containing functional groups decreased, both of which resulted in the decrease of the catalytic performance. CONCLUSION The H 2 ‐TPR and NH 3 ‐TPD results demonstrated that the catalyst prepared in the optimum conditions possessed a stronger reducing ability, more acid sites, and stronger acid strength than the other. © 2021 Society of Chemical Industry