CN104950014A - Chlorinated hydrocarbons volatile gas sensing material and preparation method thereof - Google Patents
Chlorinated hydrocarbons volatile gas sensing material and preparation method thereof Download PDFInfo
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- CN104950014A CN104950014A CN201510267241.7A CN201510267241A CN104950014A CN 104950014 A CN104950014 A CN 104950014A CN 201510267241 A CN201510267241 A CN 201510267241A CN 104950014 A CN104950014 A CN 104950014A
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Abstract
The invention discloses a chlorinated hydrocarbons volatile gas sensing material and preparation method thereof. According to the invention, a coprecipitation method is adopted for preparing a composite metal hydroxide precursor for the first time; then the precursor is arranged in a muffle furnace to be roasted so as to form a composite metal oxide material; finally the composite metal oxide material is prepared into a gas sensitive element which is applied to the detection of low-concentration chlorinated hydrocarbons gas. The composite oxide material is prepared by using low-cost materials and a simple synthesis process, the controllable preparation of serial metal oxides can be realized by micro control of preparation conditions, further the macro control of the gas sensitive performance can be realized, the composite material which has low detection limit, high sensitivity, excellent selectivity and repeatability on the chlorinated hydrocarbons volatile gas can be screened, the development potential is high, and the promotion is facilitated. Especially for ZnO/Al2O3/CuO composite oxide materials, the responding property and the selectivity of ZnO materials on low-concentration chlorinated hydrocarbon can be obviously improved by taking CuO as a reactant and Al2O3 as a dispersing agent in the gas sensitive responding process.
Description
Technical field
The invention belongs to gas sensing technical field, particularly a kind of composite oxides sensing material for chlorinated hydrocarbon escaping gas and preparation method thereof.
Background technology
Volatile organic compounds (VOCs) not only can cause room air pollution, and photo-chemical smog, secondary organic aerosol and air organic acid concentration can be caused under illumination effect to raise, and affects health and atmospheric environment.Chlorinated hydrocarbon volatile organic matter is the one in VOCs, and it refers to that hydrogen atom in alkane is replaced the organism of gained by chlorine atom, in the industrial production often by as important organic solvent and product intermediate, has carcinogenesis, aberration inducing, mutagenic harm.Such as, chloroform is the organic synthesis raw material producing fluorine Lyons, dyestuff and medicine, is a kind of poisonous suspect carcinogen, meets the phosgene that illumination can produce severe toxicity.Have the technology much detected about chlorohydrocarbon in water body at present as confocal laser-induced fluorescence, gas chromatographic analysis, high performance liquid chromatography and middle infrared acquisition etc., above instrument price is expensive, and can not reach the demand of portable detection.At present about in gas detection method, main be also the most general method is exactly that gas sensor detects.The simple portable of gas sensor, cheap, be applicable to very much the conventional sense of toxic and harmful.Wherein metal-oxide gas transducer response is fast, highly sensitive, reproducible is widely used in gas sensor.But it still exists intrinsic shortcoming, as low in low concentration detection sensitivity, working temperature is higher etc.Mainly through compound, doping and change pattern, its air-sensitive performance is improved at present.
In semiconductor material, ZnO studies more basic gas sensing materials, high to gas sensitivity, and response is fast, but poor selectivity, there is response to majority of gas.Al
2o
3mainly as dispersion and carrying agent, can well prevent material from reuniting.We propose by simple hydro-thermal method and co-precipitation high temperature sintering subsequently, prepare composite metal oxide material, improve the air-sensitive performance of object.Therefore, development and improvement simple hydro-thermal method compound substance technology of preparing has profound significance.
Summary of the invention
The object of the present invention is to provide a kind of preparation method detecting the composite oxide material of chlorinated hydrocarbon escaping gas, this material is prepared into gas sensor, probe into its sensitive natur to chlorinated hydrocarbon gas, filtered out the sensing material of best air-sensitive performance by modulation metallic element ratio.
Technical scheme of the present invention is: first adopt coprecipitation to prepare complex metal hydroxide presoma; Then presoma is placed in muffle furnace roasting, forms composite metal oxide material; Finally composite metal oxide material is prepared into gas sensor, is applied to the detection of low-level chlorinated for hydrocarbon gas.
The preparation method of chlorinated hydrocarbon escaping gas sensor of the present invention, its concrete technology step is as follows:
The mixing salt solution of preparation soluble divalent metal salt and solubility trivalent aluminium salt, wherein divalent metal M
2+and Al
3+mol ratio be 1-4, divalent metal M
2+concentration be 0.01-0.1mol/L; Preparation NaOH and Na
2cO
3mol ratio is the aqueous slkali of 1-16, and the concentration of NaOH is 1-5mol/L; Aqueous slkali and mixing salt solution are instilled in reaction bulb, in dropping process, control pH is between 6-10 simultaneously; Be transferred to after being added dropwise to complete in autoclave, in 80-150 DEG C of hydrothermal crystallizing 1-24 hour, centrifuge washing, 20-100 DEG C of drying;
(2) by presoma roasting prepared by step (1), be warming up to 500-1000 DEG C with the heating rate of 5-10 DEG C/minute, insulation 1-5 hour, obtains composite metal oxide;
(3) preparation of gas sensor:
After composite metal oxide grinding step (2) obtained, solubilizer furnishing starchiness, is then coated on ceramic pipe sensor or interdigital electrode sensor, coating thickness 0.1-1 millimeter; Finally be placed on sensor ageing platform, aging 12-120 hour under the electric current of 80-120mA.
Described M
2+be selected from Cu
2+, Zn
2+, Fe
2+and Cd
2+in one or both.Preferred molar ratio is the Zn of 1-10
2+and Cu
2+.
Described solvent is water, ethanol or ethylene glycol.
Described chlorinated hydrocarbon escaping gas is one or more in monochloro methane, methylene chloride, methenyl choloride, tetrachloromethane.
The invention has the advantages that: prepare composite oxide material with cheap raw material, simple synthesis technique, by realizing the controlled synthesis of serial composite oxides to the microcosmic regulation and control of preparation condition, and then realize the macro adjustments and controls of its air-sensitive performance, filter out compound substance chlorinated hydrocarbon escaping gas to low detectability, high sensitivity, excellent selectivity and repeatability, development potentiality is large, is conducive to promoting.Particularly ZnO/Al
2o
3/ CuO composite oxide material, in air-sensitive response process, CuO is as reactant, Al
2o
3znO material is significantly improved to the response of low concentration chlorohydrocarbon and selectivity as spreading agent.
Accompanying drawing explanation
Fig. 1 is the response to chloroform gas at the gas sensor different operating temperature that after embodiment 1,2,3 and 4 obtains roasting, composite oxides are made.
Fig. 2 is that the gas sensor made of the composite oxide material after the embodiment of the present invention 1 obtains roasting is to the response curve of variable concentrations chloroform.
Fig. 3 is that the gas sensor made of the composite oxides obtained in embodiment 1 is to the response recovery curve of 5ppm concentration chloroform.
Embodiment
[embodiment 1]
1, the preparation of composite metal oxide material
Take Zn (NO
3)
26H
2o (9.66g, 0.04mol), Al (NO
3)
39H
2o (7.5g, 0.02mol), Cu (NO
3)
2.3H
2o (5.95g, 0.02mol) is dissolved in 200 ml deionized water and stirs and obtain mixing salt solution, is designated as solution A; NaOH (6.4g, 0.16mol), Na
2cO
3(1.06g, 0.01mol) is dissolved in and obtains aqueous slkali in 80 ml deionized water and be designated as B solution; Solution A and solution B are respectively charged in buret, at the uniform velocity twoly drop in four-hole boiling flask, control pH=8 in dropping process, 30 revs/min of Keep agitation; Mixed solution is transferred in reactor, 100 DEG C of reaction 12h; Reacted solution moves in centrifugal barrel, 3500 revs/min of lower centrifugings, and deionized water centrifuge washing is to pH=7; Precipitation is placed in 60 DEG C of dryings; Take appropriate product in crucible, the programming rate of 5 DEG C/minute rises to 500 DEG C of calcinings and obtains composite oxide material ZnO/Al in 5 hours
2o
3/ CuO (Zn:Al:Cu=1:0.5:0.5).At optimum working temperature 200 DEG C, measure air-sensitive response to 50ppm chloroform, Sensitirity va1ue is 8.5, response time 20s.In addition, this gas sensor can detect 1ppm chloroform, has the repeatability that lower detectability is become reconciled.
2, gas sensor is prepared
The sample after roasting that takes a morsel, in agate mortar, adds appropriate amount of deionized water, furnishing starchiness.With writing brush, the slurries mixed up are coated on ceramic pipe, coating thickness 0.5 millimeter.Use soldering iron to be connected on base by tinsel, the middle heater strip through Ni-Cr alloy is also fixing.The gas sensor welded is placed on special agingtable, 80mA electric current is set, aging 12 hours.Aging rear mensuration its to the air-sensitive performance of chlorohydrocarbon gas.
3, air-sensitive performance test
The optimum working temperature of 3.1 test gas sensors
A. blow off 5L distribution bottle, vacuum pump evacuation with hair-dryer, then extract chlorohydrocarbon liquid with microsyringe, penetrate the chlorohydrocarbon gas atmosphere preparing 50ppm in distribution bottle, fully volatilize, for subsequent use.
B. by regulating the electric current by heater strip, device heats temperature is changed.Under testing different electric current, device resistance changes, and records corresponding R
a, R
gvalue.Device gas response S=R
a/ R
g, according to the R of record
aand R
gchange, with Origin mapping, obtain the change curve of response device value with heating current, thus obtain the optimum working temperature of gas sensor, as shown in Figure 1.
The relation of 3.2 test air-sensitive responses and concentration
Under device recommended current, 5L gas cylinder is adopted to prepare the chlorohydrocarbon gas of series concentration successively, measure the air-sensitive response of gas sensor to chlorohydrocarbon gas under variable concentrations and the relation curve of concentration, be illustrated in figure 2 the air-sensitive response of gas sensor to chloroform escaping gas and the relation curve of concentration.
The repeated curve of 3.3 tests to chlorinated hydrocarbon gas
A. blow off 5L distribution bottle, vacuum pump evacuation with hair-dryer, then extract chlorohydrocarbon liquid with 1 μ L microsyringe, penetrate the chlorohydrocarbon atmosphere preparing 5ppm in distribution bottle, fully volatilize, for subsequent use.
B. regulate electric current to device best operating condition, the aerial stable electrical resistance of gas sensor, then element is placed in 5ppm chlorohydrocarbon atmosphere, the resistance value of measuring element in object gas, after resistance is stable, again expose in atmosphere, resistance reaches stable again, repeat 4 times, measure corresponding R
a, R
gvalue, imported by data measured in Origin software and map, Fig. 3 is the response recovery curve of element for chloroform escaping gas.
Above-mentioned air-sensitive performance evaluation method adopts Beijing to end chemical gas sensing-8 (CGS-8) test macro of Lyntech Corporation (US) 10177 South 77th East Avenue Tulsa, Oklahoma 74133 U.S. (ELITE TECH), measures the device for preparing to the response performance of chlorinated hydrocarbon escaping gas.Device sensitivity S=R
a/ R
g, R
abasic resistance in-air, R
gresistance in-object gas.Response time is defined as sensor contacts to object gas, and resistance is from R
ato R
a-90% × (R
a-R
g) time, be defined as sensor release time and remove R when object gas is placed in air
gto R
g+ 90% × (R
a-R
g) time.
[embodiment 2]
1, the preparation of material
Take (Zn (NO
3)
26H
2o (12.08g, 0.05mol), Al (NO
3)
39H
2o (7.5g, 0.02mol), Cu (NO
3)
2 .3H
2o (2.42g, 0.01mol) is dissolved in 200 ml deionized water and stirs and obtain salt solusion, and remaining reaction condition is in the same manner as in Example 1, finally obtains ZnO/Al
2o
3/ CuO (Zn:Al:Cu=1:0.2:0.4) composite metal oxide.
2, gas sensor is prepared as embodiment 1.
3, test process is as embodiment 1, and result as shown in Figure 1.
[embodiment 3]
1, Zn (NO is taken
3)
26H
2o (23.80g, 0.08mol), Al (NO
3)
39H
2o (11.26g, 0.03mol), Cu (NO
3)
23H
2o (2.38g, 0.01mol) is dissolved in 200mL deionized water and stirring and evenly obtains salt solusion, and remaining reaction condition is in the same manner as in Example 1, finally obtains ZnO/Al
2o
3/ CuO (Zn:Al:Cu=1:0.375:0.125) composite metal oxide.
2, gas sensor is prepared as embodiment 1.
3, test process is as embodiment 1, and result as shown in Figure 1.
[embodiment 4]
1, Zn (NO is taken
3)
26H
2o (9.66g, 0.04mol), Al (NO
3)
39H
2o (7.5g, 0.02mol) is dissolved in 200 ml deionized water and stirs and obtain mixing salt solution, and remaining reaction condition is in the same manner as in Example 1, finally obtains ZnO/Al
2o
3(Zn:Al=1:0.5) composite metal oxide.
2, gas sensor is prepared as embodiment 1.
3, test process is as embodiment 1, and result as shown in Figure 1.
Claims (5)
1. a preparation method for chlorinated hydrocarbon escaping gas sensor, is characterized in that, its concrete technology step is as follows:
(1) preparation of presoma:
The mixing salt solution of preparation soluble divalent metal salt and solubility trivalent aluminium salt, wherein divalent metal M
2+and Al
3+mol ratio be 1-4, divalent metal M
2+concentration be 0.01-0.1mol/L; Preparation NaOH and Na
2cO
3mol ratio is the aqueous slkali of 1-16, and the concentration of NaOH is 1-5mol/L; Aqueous slkali and mixing salt solution are instilled in reaction bulb, in dropping process, control pH is between 6-10 simultaneously; Be transferred to after being added dropwise to complete in autoclave, in 80-150 DEG C of hydrothermal crystallizing 1-24 hour, centrifuge washing, 20-100 DEG C of drying;
(2) by presoma roasting prepared by step (1), be warming up to 500-1000 DEG C with the heating rate of 5-10 DEG C/minute, insulation 1-5 hour, obtains composite metal oxide;
(3) preparation of gas sensor:
After composite metal oxide grinding step (2) obtained, solubilizer furnishing starchiness, is then coated on ceramic pipe sensor or interdigital electrode sensor, coating thickness 0.1-1 millimeter; Finally be placed on sensor ageing platform, aging 12-120 hour under the electric current of 80-120mA.
2. preparation method according to claim 1, is characterized in that, described M
2+be selected from Cu
2+, Zn
2+, Fe
2+and Cd
2+in one or both.
3. preparation method according to claim 1, is characterized in that, described M
2+for mol ratio is the Zn of 1-10
2+and Cu
2+.
4. preparation method according to claim 1, is characterized in that, described solvent is water, ethanol or ethylene glycol.
5. preparation method according to claim 1, is characterized in that, described chlorinated hydrocarbon escaping gas is one or more in monochloro methane, methylene chloride, methenyl choloride, tetrachloromethane.
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ID=54164828
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0206839A3 (en) * | 1985-06-28 | 1987-12-09 | National Research Development Corporation | Gas sensors and methods of their fabrication |
| CN1746130A (en) * | 2005-04-26 | 2006-03-15 | 北京化工大学 | Nanometer gas-sensing material of ternary composite metal oxide and production thereof |
| CN1746131A (en) * | 2005-05-19 | 2006-03-15 | 北京化工大学 | Gas-sensing material with noble metal doped composite metal oxide and its production |
| CN102628824A (en) * | 2012-04-16 | 2012-08-08 | 北京化工大学 | Gas sensitive element taking houghite as precursor and preparation method thereof |
-
2015
- 2015-05-24 CN CN201510267241.7A patent/CN104950014A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0206839A3 (en) * | 1985-06-28 | 1987-12-09 | National Research Development Corporation | Gas sensors and methods of their fabrication |
| CN1746130A (en) * | 2005-04-26 | 2006-03-15 | 北京化工大学 | Nanometer gas-sensing material of ternary composite metal oxide and production thereof |
| CN1746131A (en) * | 2005-05-19 | 2006-03-15 | 北京化工大学 | Gas-sensing material with noble metal doped composite metal oxide and its production |
| CN102628824A (en) * | 2012-04-16 | 2012-08-08 | 北京化工大学 | Gas sensitive element taking houghite as precursor and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 聂美香 等: ""低浓度氯仿气体响应的ZnO/CuO/Al2O3异质结材料"", 《第十三届固态化学与无机合成学术会议论文摘要集》 * |
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Application publication date: 20150930 |