Direct catalytic decomposition of nitric oxide. Final report
This project investigated a suitable catalyst system for the direct NO decomposition for post-combustion NO{sub x} control. The studied process does not use a reductant, such as ammonia in the case of Selective Catalytic Reduction (SCR) process for catalytic reduction of NO{sub x} to nitrogen. This is a simplified process basically involving passing the flue gas through a catalytic converter, thus avoiding problems generally associated with the commercial SCR process, namely high operating cost, ammonia slip, and potential N{sub 2}O emissions. The main results from this research project are summarized in the following: Cu-ZSM-5 and M/Cu-ZSM-5 were synthesized by incorporating metal cations into ZSM-5 zeolite supports by optimized ion exchange procedures. It was found that (1) the catalytic activity of Cu-ZSM-5 only increased with copper loading when the Cu-ZSM-5 was prepared in an aqueous copper acetate solution with pH lower than 5.74; (2) high pH of the solution led not only to ion-exchanged Cu{sup 2+}, but also copper deposition on the zeolite surface forming inactive CuO particles as identified by STEM/EDX and XRD; (3) the sequence of metal ion exchange first, followed by copper ion exchange to synthesize M/Cu-ZSM-5, where M represents any metal ion but copper, was important for the cocation to show promotion effects; and (4) air-calcination of M-ZSM was effective in keeping M cations in the zeolite during subsequent copper ion exchange. Positive alkaline and rare earth metal cocation effects on the Cu-ZSM-5 were identified in oxygen-containing gas mixtures in the high temperature region (450--600C). Cerium ion promoted the Cu-ZSM-5 activity in the low temperature range (< 450C) in oxygen-free gas mixture, while alkaline earth and transition metal cocations improved the NO conversion to N{sub 2} in high temperature region.
- 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:
- 111932
- Report Number(s):
- DOE/PC/91293-T5; ON: DE95017760
- Resource Relation:
- Other Information: PBD: 15 Jun 1995
- Country of Publication:
- United States
- Language:
- English
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