Abstract
Ammonia (NH3) is one of valuable chemicals which is commonly used in manufacturing the fertilizer, synthetic fiber, synthetic plastics, and dynamites, and is used in the factories such as papermaking, textile mill, camera and electrical. NH3 is also a typical pollutant which is found to be emitted from industrial processes, agriculture areas and livestock farm. It causes burn damage due to the corrosion and has a long-term impact on human bronchus.
This study was to investigate the performance and kinetics in oxidation of ammonia by using a method of selective catalytic oxidation (denoted by SCO) over a series catalysts of Cu/Ce . The major parameters were performed at the following conditions: initial concentration NH3 of influent in ranging from 500 ppm to 1000 ppm, temperatures ranging from 150¢J to 500¢J, oxygen content in inlet stream in ranging from 4¢Hto 20¢Hand humidity in ranging from 1¢Hto 20¢H(or an absolute humidity of 607 ppm-12136 ppm).
In the first stage experiments, the purpose was to select a best catalyst, which had the great activity and highest selectivity on nitrogen. The catalysts used in this work were prepared into three types in the following: Cu/La/Ce (molar ratio: 8/1/1, 7/1/2, 7/2/1, 6/1/3, 6/2/2 and 6/3/1), Cu/La (molar ratio: 6/4, 7/3, 8/2 and 9/1) and Cu/Ce (molar ratio: 6/4, 7/3, 8/2 and 9/1); total numbers of catalysts were 14. Test results showed the molar ratio 6:4 of Cu/Ce catalyst was found to have the best activity and selectivity to convert NH3 in this work.
The second stage experiments were carried to investigate the effect of parameters on conversion of NH3 over a Cu/Ce catalyst of molar ratio 6:4. The conversion of NH3 in process of SCO increased with operation conditions such as the going up of temperature, and the increasing both of oxygen content and of residence time. The lower conversion of NH3 was achieved by an increasing on initial concentration of NH3, space velocity and humidity.
The third stage experiments were conducted to investigate the effect of operation period on deactivation of NH3 over the above catalyst. At constant initial concentration of NH3, oxygen content and space velocity for 30 hr continuously, we found Cu/Ce catalyst had an excellent stability in conversion of NH3. Further tests by XRD, SEM and EA were determined.
The kinetics of SCO over a Cu/Ce catalyst of molar ratio 6:4 in oxidation of NH3, using differential method, was found that a pseudo-first order reaction could be described by Mars-Van Krevelend model. An equation of destruction efficiency in terms of NH3 was obtained, and a good fitting was got between the predicted and the experimental values.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0711102-170720 |
| Date | 11 July 2002 |
| Creators | Yang, Sheng-Fu |
| Contributors | Kang-Shin Chen, Jie-Chung Lou, Chung-Bang Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0711102-170720 |
| Rights | unrestricted, Copyright information available at source archive |
Page generated in 0.002 seconds