Magnetic resonance studies of reactions of urea and nitric oxide on FeZSM-5, HZSM-5 and silicalite

• Published in: Journal of molecular catalysis. A, Chemical Vol. 212; no. 1; pp. 329 - 336
• Main Authors: Jones, Conrad A., Stec, Donald, Larsen, Sarah C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02-04-2004; Elsevier
• Subjects: Catalysis; Chemistry; EPR; Exact sciences and technology; FeZSM-5; General and physical chemistry; HZSM-5; Ion-exchange; SCR; Silicalite; Solid state NMR; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Urea; Zeolites; Zeolites: preparations and properties; Urea; SCR; FeZSM-5; EPR; Solid state NMR; Silicalite; HZSM-5; Zeolites; FeZSM-5: Silicalite; Magnetic resonance; NMR spectrometry; Zeolite; Molecular sieve; Heterogeneous catalysis; Solid state; Nitric oxide
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2003.11.014

Solid state NMR experiments were used to investigate the reactions of urea and NO on H- and FeZMS-5 demonstrating the potential of these materials for the selective catalytic reduction of NO with urea.
Urea is a potential reducing agent for the selective catalytic reduction (SCR) of NO
x
. In this study,
13
C
and
15
N
solid state magic angle spinning nuclear magnetic resonance (MAS NMR) experiments were used to investigate the reactions of labeled urea (
13
C
and
15
N
) alone and with nitric oxide (NO) and oxygen on FeZSM-5 (Fe/Al=0.11), HZSM-5 and silicalite (purely siliceous form of ZSM-5) after thermal treatments at different temperatures. The hydrolysis of labeled urea to carbon dioxide and ammonia on FeZSM-5 and HZSM-5 after thermal treatments at elevated temperatures was observed using
13
C
and
15
N
MAS NMR. Reactions of NO, urea and oxygen on HZSM-5, FeZSM-5 and silicalite were also monitored with
13
C
and
15
N
MAS NMR. On both HZSM-5 and FeZSM-5, urea, NO and oxygen reacted to form nitrogen, carbon dioxide and ammonia. On silicalite, urea, NO and oxygen reacted to form CO
2, ammonia and a side product with an imine functionality. No nitrogen was formed on silicalite. EPR spectroscopy was used to investigate the environment of the iron in FeZSM-5.