Catalytic reduction of NO by CH[sub 4] over Li-promoted MgO

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1095· OSTI ID:7197728

Zhang, X; Walters, A B; Vannice, M A ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States)

NO reduction by CH[sub 4] was conducted in a quartz microreactor from 773 to 953 K over a series on nonmetallic catalysts typically used for CH[sub 4] oxidative coupling-MgO, 1 wt% Li/MgO, 4 wt% Li/MgO, and 16 wt% Li/MgO. This represents a new family of catalysts for NO reduction by CH[sub 4] which has not previously been investigated. All four catalysts were active for NO reduction in the absence of molecular O[sub 2], but the specific activities of N[sub 2] formation ([mu]mol N[sub 2]/s[center dot]m[sup 2]) over the Li/MgO samples were almost five times higher than that over pure MgO, indicating that lithium promotes NO reduction, however, NO reduction was not a strong function of lithium loading. No direct NO decomposition occurred over an sample in the absence of CH[sub 4]. The apparent activation energy for NO reduction to N[sub 2] by CH[sub 4] over all four catalysts was 29.0 [+-] 1.1 kcal/mol; thus, there was no correlation between activation energies and lithium loadings. For these four catalysts at 923 K in the absence of oxygen, reaction orders in CH[sub 4] and NO were approximately 0.73 [+-] 0.11 and 0.43 [+-] 0.05, respectively. These catalysts were also active with O[sub 2] in the feed but NO conversion decreased and CH[sub 4] conversion increased, although the inhibiting effect of O[sub 2] on NO reduction to N[sub 2] as less at a higher temperature. The apparent activation energy in the presence of 1.0% O[sub 2] shifted to a higher value of 35.0 [+-] 1.0 kcal/mol with all four catalysts, and a negative reaction order in O[sub 2] of -0.54 [+-] 0.13 was determined at 923 K. Over the three Li/MgO catalysts, the apparent activation energy for N[sub 2]O formation was 19.7 [+-] 1.8 kcal/mol. 30 refs., 8 figs., 4 tabs.

• OSTI ID: 7197728
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 146:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKANES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
ENERGY
HYDROCARBONS
KINETICS
LITHIUM
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
METHANE
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
REDUCTION