Direct catalytic decomposition of nitric oxide. Quarterly technical progress report No. 13, October--December 1994
This project investigates a suitable catalyst system for direct NO decomposition in post-combustion gas streams. This process does not use a reductant, such as the ammonia used in Selective Catalytic Reduction (SCR) of NO{sub x} to nitrogen. Therefore, it is a greatly simplified process involving passing the flue gas through a catalytic converter. Catalysts are prepared by incorporating metal cations into zeolite supports according to ion exchange procedures widely used in preparation of metal/zeolite catalysts. The catalysts of primary interest are copper, cerium, palladium, silver, and nickel exchanged ZSM-5 catalysts. Particular emphasis is given in this work on promoted Cu-ZSM-5 zeolites, especially the catalyst system Mg/Cu-ZSM-5, Ce/Cu-ZSM-5 and a few others, which are promising for NO conversion to nitrogen at typical flue gas 0{sub 2} and NO levels and over the temperature range of 723--873K. The effect of zeolite modification, copper exchange level and catalyst preparation conditions on the catalyst activity are studied in a packed-bed microreactor. Kinetic studies of NO and 0{sub 2} interaction with catalysts over a wide temperature range as well as catalyst structural investigations by STEM/EDX, XRD, and XPS are aimed at elucidating the role of cocation on the copper ion activity and stability in dry and wet reaction mixtures. During this quarter, the atomic ratios of copper, cerium, oxygen, and silicon on the surface of fresh, and used Cu-ZSM-5 and Ce/Cu-ZSM-5 catalysts were measured by x-ray-excited photoelectron spectroscopy (XPS). Dynamic change of copper with treatment of the samples was identified. Enrichment of copper was found in hydrated and steamed samples, while copper migrated into zeolite channels after the samples were heated in dry gas streams. Cerium was highly concentrated on the zeolite surface regions, and was much less mobile than copper.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91293
- OSTI ID:
- 39698
- Report Number(s):
- DOE/PC/91293-13; ON: DE95010500
- Resource Relation:
- Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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