CN1330975A - Microwave-discharging catalytic reducing process for removing nitrogen oxide - Google Patents
Microwave-discharging catalytic reducing process for removing nitrogen oxide Download PDFInfo
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- CN1330975A CN1330975A CN 00110575 CN00110575A CN1330975A CN 1330975 A CN1330975 A CN 1330975A CN 00110575 CN00110575 CN 00110575 CN 00110575 A CN00110575 A CN 00110575A CN 1330975 A CN1330975 A CN 1330975A
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- microwave
- catalyst
- discharge
- oxynitrides
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Abstract
A microwave discharge method for removing nitrogen oxide by catalytic reduction features that CH4 is used as reducer, the molecular sieve H2SM-5 or the Fe carried by it is used as catalyst, and a low-power (30-80 W) microwave is used to discharge in catalyst bed to directly converting NOx to N2. Its advantages are high activity of catalyst and selective reduction of NOx.
Description
The present invention relates to the crossing domain of microwave energy utilization and chemical catalysis, a kind of microwave-discharging catalytic reducing NO is provided
xNew method, a kind of microwave discharge Catalysts and its preparation method also is provided simultaneously.
Environmental Pollution and Control is the problem of attracting worldwide attention, wherein NO
xElimination more extremely pay close attention to various countries.NO is eliminated in catalysis
xIt is the purification techniques of present most widely used in the world processing oxynitrides.Hydro carbons selective reduction NO
x(SCR) be acknowledged as elimination NO now
xThe method of using future is arranged most.And natural gas (its main component is a methane) reserves are abundant, more than the easier acquisition of other hydro carbons, not only are widely used in industrial production, and almost are present in the tail gas of each fuel, therefore, use methyl hydride catalyzed reductive NO
xBe a kind of practicality and inexpensive method.The patent of U.S.Pat.No.5149112 points out that under the oxygen-containing atmosphere, an amount of methane is reducing agent, and the Co-ZSM-5 activity of ion-exchange preparation is best.JP06,262,039 propose under the indium catalyst action that ZSM-5 molecular sieve or ferrierite support, and when aerobic existed, methane and carbon monoxide acted on simultaneously, can effectively remove oxynitrides.In addition, relevant document has also reported with methane to be reducing agent, under the oxygen existence condition, and the NO of catalyst such as Ga/HZSM5, Pd/HZSM5
xConversion ratio is also higher.But along with the increase of oxygen concentration, gas space velocity, such activity of such catalysts all descends greatly.At the problems referred to above, the new way of eliminating oxynitrides is all being explored in countries in the world.U.S. FORD company and Canadian Queens University have at first been carried out the laboratory principle research of microwave catalysis processing vehicle exhaust in the world in 93 years, the catalyst that is adopted is Pt/Cordierite or Pd/Cordierite, because this catalyst is to the utilization rate too low (＜30%) of microwave, do not achieve satisfactory results, only improve 5% than conventional treatment method.
Utilize corona discharge to remove that pollutant also is a kind of well-known method in the waste gas.People such as Puchkarev have set forth the research of " elimination of toxic gas under discharging condition " comprehensively in international plasma meeting in 1994.Inquired into the elimination of discharge in the Ser.No.08/29595 patent, and applied by Hughes Aircraft company to liquid pollutant.People such as Yamamoto have also described by corona discharge pulse and have eliminated VOC refuses such as (VOCs).U.S.Pat.No.4695358 has also pointed out to remove SO in the gas with the high direct voltage discharge
xAnd NO
xAbove discharge technology all belongs to the high direct voltage discharge, shown the higher advantage of its conversion ratio, but shortcoming is obvious, and is very low as its capacity usage ratio of pointing out in U.S.Pat.No.5807466 people such as Wang, and has problems such as electrode erosion and electrode fouling.
Microwave discharge is compared than the high direct voltage discharge, the former active constituent (electronics, negative ions and free radical) temperature is high more a lot of than the latter, and the overall gas mean temperature is much lower than the latter, thereby in chemical application facet, compare with the high direct voltage discharge, microwave discharge can improve capacity usage ratio greatly; Simultaneously can realize electrodeless discharge.
The object of the present invention is to provide a kind of microwave-discharging catalytic reducing to remove the method for oxynitrides, it can cheap CH
4Be reducing agent, under a large amount of oxygen existence conditions of normal pressure, eliminate oxynitrides with microwave discharge catalysis, method is simple, efficient height, non-secondary pollution.
The invention provides the method that a kind of microwave-discharging catalytic reducing removes oxynitrides, it is characterized in that: with CH
4Be reducing agent, oxygen exists under the situation; Is catalyst with silica alumina ratio less than 38 HZSM-5 molecular sieve; Discharge in beds with low power microwave, microwave input power is 30-80W, with NO
xBe converted into N
2
Can also support iron on the used HZSM-5 molecular sieve catalyst among the present invention, the weight percentage of iron is 1-20%, is preferably 5-10%.
Key of the present invention is to provide a kind of special catalyst, and the catalyst that microwave discharge catalysis requires should have wave-sucking performance, to guarantee carrying out microwave discharge; Simultaneously wave-sucking performance again can not be too strong, otherwise only can cause heating using microwave and be difficult to realize discharge, and this catalyst will have the catalytic activity of part, and the active component that possesses above-mentioned feature can also have Mn, Cd, V, Ni, Co.Catalyst provided by the invention is by adopting infusion process to make soluble metal salt and molecular sieve, having satisfied above-mentioned requirements.Promptly oxynitrides is eliminated and is had certain catalytic action, utilize the absorbing property of iron to cause microwave simultaneously without electrode causes discharge and in beds, discharge, realized the iron molecule sieve be catalyst be again the discharge initator.
Microwave-discharging catalytic reducing NO of the present invention
xMechanism be to form many active components (electronics, negative ions and free radical), active component and ground state NO by microwave discharge
xAnd CH
4Molecules strike and produced high activity, astable NO
x, CH
x,, they are reacted, at catalyst surface with NO by the selection of catalysts reduction
xBe converted into N
2
Method for preparing catalyst provided by the invention is simple, and the production specifications that required microwave discharge catalytic unit is existing ripe help technology and amplify, and for the elimination of oxynitrides great Practical significance is arranged.Below by embodiment in detail the present invention is described in detail.
Accompanying drawing 1 is the signal of microwave discharge structure of reactor
The preparation of embodiment 1 discharge catalytic agent
The preparation of the molecular sieve discharge catalytic agent of iron content 10% (weight percentage).Molecular sieve is HZSM-5, is provided by Catalyst Factory, Nankai Univ.At first the ferric nitrate crystal is dissolved in the deionized water, is configured to the aqueous solution of iron content 5%; Measure this solution of certain volume and pour among isopyknic HZSM-5, after fully stirring, left standstill 2 hours, 120 ℃ were dried by the fire 4～13 hours, placed 500～700 ℃ of roastings of muffle furnace 4 hours, shifted out after cooling; Flood once by same step then, reaching the iron loading is 10% again.Before the reaction, with the catalyst compressing tablet, break into pieces, it is standby to sieve out 30～60 purpose particles.
When embodiment 2 exists at a large amount of oxygen, be catalyst with pure HZSM-5, conventional heatable catalytic and microwave discharge catalysis are to NO
xThe influence that removes
Atmosphere is in the example; NO, 2000ppm; CH
4, 1600ppm; O
2, 2%, all the other are He.Reactor is the individual layer quartz ampoule, internal diameter 25mm (seeing accompanying drawing 1).The each loading amount 1ml of catalyst, air speed 3600h
-1After question response is stablized 0.5 hour, product is analyzed with gas-chromatography and five component analysis instrument.
The table 1.HZSM-5 when routine heats to NO
xRemove
NO
xConversion ratio
Temperature (℃) CH
4Conversion ratio (%)
(％)
300 1.8 0.8
400 7.5 5.5
450 13.4 17.3
500 11.7 26.8
550 9.2 34.3
600 9.2 62.2
700 10.9 100.0 original atmosphere: NO:2000ppm, CH
4: 1600ppm, O
2: 2%, total flow: 60ml/min
The table 2.HZSM-5 when microwave discharge to NO
xRemove
Catalyst microwave input power NO
xConversion ratio CH
4Conversion ratio
(W) (％) (％)
No 43-54 18 68.2
HZSM-5 43-54 38.0 73.9
54-65 39.5 73.3 original atmosphere: NO:2000ppm, CH
4: 1600ppm, O
2: 2%, total flow: 60ml/min
Do not have: in the empty reactor of catalyst-free, pure discharge is to NO
xChanging effect embodiment 3 when a large amount of oxygen exist, be catalyst with Fe (10%)/HZSM-5, conventional heatable catalytic and microwave discharge catalysis are to NO
xThe influence that removes
Atmosphere is in the example; NO, 2000ppm; CH
4, 1600ppm; O
2, 2%, all the other are He.Reactor is the individual layer quartz ampoule, internal diameter 25mm.The each loading amount 1ml of catalyst, air speed 3600h
-1After question response is stablized 0.5 hour, product is analyzed with gas-chromatography and five component analysis instrument.
The table 3.Fe (10%)/HZSM-5 when routine heats to NO
xRemove
Temperature (℃) NO
xConversion ratio (%) CH
4Conversion ratio (%)
300 0.7 2.0
400 3.5 4.5
500 5.4 7.3
600 4.4 9.0
650 3.0 27.3
700 3.3 81.3
740 2.1 100.0 original atmosphere: NO:2000ppm, CH
4: 1600ppm, O
2: 2%, total flow: 60ml/min
The table 4.Fe (10%)/HZSM-5 when microwave discharge to NO
xRemove
Catalyst microwave input work NO
xConversion ratio CH
4Conversion ratio (%)
Rate (W) (%)
No 43-54 18 68.2
Fe/HZSM-5 43-54 37.2 42.6
54-65 42.0 47.3
65-76 44.5 50.5 original atmosphere: NO:2000ppm, CH
4: 1600ppm, O
2: 2%, total flow: 60ml/min
Do not have: in the empty reactor of catalyst-free, pure discharge is to NO
xChanging effect
Claims (4)
1, a kind of microwave-discharging catalytic reducing removes the method for oxynitrides, it is characterized in that: with CH
4Be reducing agent, oxygen exists under the situation; Is catalyst with silica alumina ratio less than 38 HZSM-5 molecular sieve; Discharge in beds with low power microwave, microwave input power is 30-80W, with NO
xBe converted into N
2
2, remove the method for oxynitrides by the described microwave-discharging catalytic reducing of claim 1, it is characterized in that: support iron on the used HZSM-5 molecular sieve catalyst, the weight percentage of iron is 1-20%.
3, remove the method for oxynitrides by the described microwave-discharging catalytic reducing of claim 2, it is characterized in that: the iron percentage by weight is 5-10% in the catalyst system therefor.
4, remove the method for oxynitrides by the described microwave-discharging catalytic reducing of claim 1, it is characterized in that: support Mn, Cd, V, Ni, Co on the used HZSM-5 molecular sieve catalyst.
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|---|---|---|---|
| CN 00110575 CN1330975A (en) | 2000-06-28 | 2000-06-28 | Microwave-discharging catalytic reducing process for removing nitrogen oxide |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00110575 CN1330975A (en) | 2000-06-28 | 2000-06-28 | Microwave-discharging catalytic reducing process for removing nitrogen oxide |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102489152A (en) * | 2011-12-30 | 2012-06-13 | 湘潭大学 | Denitration method by microwave catalytic reaction for direct decomposition of NO |
| WO2013097677A1 (en) * | 2011-12-30 | 2013-07-04 | 湘潭大学 | Microwave catalyst and preparation process and use thereof |
| CN103961987A (en) * | 2014-05-16 | 2014-08-06 | 电子科技大学 | Microwave-plasma-based nitrogen oxide removal device |
| CN104474889A (en) * | 2014-12-05 | 2015-04-01 | 湘潭大学 | Catalytic denitrification method |
| CN104645974A (en) * | 2015-01-29 | 2015-05-27 | 中国石油大学(北京) | Catalyst for FCC regeneration flue gas denitration, preparation method and application thereof |
| CN108187732A (en) * | 2017-12-12 | 2018-06-22 | 哈尔滨工业大学深圳研究生院 | A kind of CH of sulfur resistive water resistant4SCR denitration and preparation method thereof |
| CN109821372A (en) * | 2019-02-21 | 2019-05-31 | 东华大学 | A kind of microwave induced metal discharge carries out the device and method of denitrating flue gas |
-
2000
- 2000-06-28 CN CN 00110575 patent/CN1330975A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102489152A (en) * | 2011-12-30 | 2012-06-13 | 湘潭大学 | Denitration method by microwave catalytic reaction for direct decomposition of NO |
| WO2013097677A1 (en) * | 2011-12-30 | 2013-07-04 | 湘潭大学 | Microwave catalyst and preparation process and use thereof |
| CN102489152B (en) * | 2011-12-30 | 2014-05-21 | 湘潭大学 | Denitration method by microwave catalytic reaction for direct decomposition of NO |
| US9168514B2 (en) | 2011-12-30 | 2015-10-27 | Xiangtan University | Microwave catalyst and preparation process and use thereof |
| CN103961987A (en) * | 2014-05-16 | 2014-08-06 | 电子科技大学 | Microwave-plasma-based nitrogen oxide removal device |
| CN103961987B (en) * | 2014-05-16 | 2015-12-09 | 电子科技大学 | A kind of oxynitrides based on microwave plasma removes device |
| CN104474889A (en) * | 2014-12-05 | 2015-04-01 | 湘潭大学 | Catalytic denitrification method |
| CN104474889B (en) * | 2014-12-05 | 2016-10-05 | 湘潭大学 | A kind of method of catalytic denitration |
| CN104645974A (en) * | 2015-01-29 | 2015-05-27 | 中国石油大学(北京) | Catalyst for FCC regeneration flue gas denitration, preparation method and application thereof |
| CN108187732A (en) * | 2017-12-12 | 2018-06-22 | 哈尔滨工业大学深圳研究生院 | A kind of CH of sulfur resistive water resistant4SCR denitration and preparation method thereof |
| CN108187732B (en) * | 2017-12-12 | 2021-04-02 | 哈尔滨工业大学深圳研究生院 | Anti-sulfur and water-resistant CH4-SCR denitration catalyst and preparation method thereof |
| CN109821372A (en) * | 2019-02-21 | 2019-05-31 | 东华大学 | A kind of microwave induced metal discharge carries out the device and method of denitrating flue gas |
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