CN102671688B - Ozone decomposition composite catalyst and preparation method thereof - Google Patents
Ozone decomposition composite catalyst and preparation method thereof Download PDFInfo
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- CN102671688B CN102671688B CN201210143136.9A CN201210143136A CN102671688B CN 102671688 B CN102671688 B CN 102671688B CN 201210143136 A CN201210143136 A CN 201210143136A CN 102671688 B CN102671688 B CN 102671688B
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Abstract
The invention discloses an ozone decomposition composite catalyst and a preparation method thereof. The composite catalyst is prepared by mixing iron modified zeolite and iron modified quartz sand in a mass ratio of 1:4-4:1. The preparation method of the composite catalyst comprises the following steps: modifying zeolite with nano hydroxyl iron oxide to prepare iron modified zeolite, modifying quartz sand with iron ions in an alkalifying mode to prepare the iron modified quartz sand, and proportionally mixing the modified zeolite and the modified quartz sand to obtain the composite catalyst disclosed by the invention. The composite catalyst not only can display the heating of quartz sand to enhance the thermal decomposition action on O3, but also can display the adsorptive decomposition effect of the modified zeolite, and thus, has the advantages of high decomposition rate, high safety, no self consumption, long service life, no harmful substance generation and the like.
Description
Technical field
The present invention relates to ozone decomposition catalyst technical field, particularly a kind of ozone decomposed composite catalyst and preparation method thereof.
Background technology
Ozone (O
3) significant to life on earth, ozone layer can absorb the ultraviolet ray below sunlight medium wavelength 306.3nm, is the umbrella that the mankind and life on earth are depended on for existence, protects it to exempt from intensive ultraviolet injury.But near-earth O
3pollute and indoor O
3but can produce serious harm to human body and the ecosystem.Research shows, works as O
3when concentration exceedes 0.05ppm, health is worked the mischief, while exceeding 0.1ppm, directly breathing and the motion function to human body impacts.O
3can cause people's neurotoxic, dizziness headache, visual impairment, be losing one's memory.Indoor O
3very complicated from chemical reaction and product that different organic substances occur, product comprises that carcinogen is as formaldehyde, methacrylaldehyde etc., and pungent is as carbonyl, dicarbapentaborane, acids etc., and free radical, secondary Organic aerosol etc.Excessive concentrations near-earth O
3be there is to toxic action in plant growth, affect its growth and crop yield.O
3be to have corrosive gas, can accelerate degraded and the aged deterioration of multiple macromolecular material, various metals and inorganic material are also had to strong corrosiveness, the estimated amount of damage whole world of causing thus reaches multi-million dollar every year.As can be seen here, O
3so big on the impact of environment.Therefore, near-earth and indoor O
3the harm causing must cause people's great attention.
Abroad for O
3healthy mechanism research and control technology research start from the eighties in last century, except having built perfect monitor network, importantly work out corresponding electric equipment products monitoring standard, wherein, in UL867 standard (electrostatic air cleaner), specified specially the O of air purifier
3concentration control detection method.The NIKKI of Japan and the ingelhard company of the U.S. are the companies that produces specially catalyst, at O
3in catalytic purification filter product, have multinomial patent and company standard.The airmpro radiator coating of the VOlVO motor corporation exploitation of Sweden, is specifically designed to environment O
3eliminate.The International Olympic Committee also contrasts the O of Games-time
3concentration has been carried out clear and definite regulation, as environment O
3concentration is during higher than 0.080ppm, and most strenuous exercises athletics event must not be held.NAS and national project institute have also set up special mechanism for this reason, strengthen O
3the research of pollution problem.
Domestic for near-earth O
3with indoor O
3the research of polluting is started late, but in recent years along with to O
3the attention of contamination hazard, is specifically designed to low concentration O
3the product of catalytic purification increases increasingly, for example, for the O of electrostatic air cleaner
3filter, the O on duplicator, laser printer
3filter, central air-conditioning VMC O
3the products such as filter increase gradually, and still, domestic still do not have this series products core component a---O
3the examination criteria of filter.Domestic examination criteria that at present can reference is UL867 " electrostatic air cleaner ", but the complete machine that is only suitable for electrostatic air cleaner detects.
The control approach of current ozone pollution and the problem of existence:
Main O at present
3decomposition method has dilution method, washing method (liquid absorption process), thermal decomposition method, electromagenetic wave radiation decomposition method, active carbon adsorption, catalytic decomposition etc.
Dilution method contains O with the fresh air dilution in ventilating system
3tail gas.But directly reach emission 1.46 × 10
-9molL
-1o
3the required thinner ratio of Security Target is very high.So this method is only at residue O
3further utilize, guarantee that suitable atmospheric dilution is such as 8～10, connect exhaust chimney and be only practicable afterwards.Advantage is that operating cost is low, and equipment is simple; Subject matter is that noise is excessive, and effect is general.
Washing method.In spray column, water washs tail gas, removes O wherein
3.Shortcoming is that equipment is huge, and effect is general.
Thermal decomposition method.O
3more stable in air than in water, O under room temperature
3at the half-life of gas phase 4～16hr not etc.O in air
3thermal decomposition start as far back as 30 DEG C, remarkable in the time of 40～50 DEG C.O within 200 DEG C of next minutes
3decompose while being approximately 70%, 230 DEG C 92%～95%.At 270 DEG C or when above, in 1～2s reaction time, reach 100% decomposition.Therefore thermal decomposition method is current for eliminating the contained O of tail gas
3most popular technology, main technique has single channel resistance heated, heats, heats and three kinds of modes of overheated burning by heat exchange.But current thermal decomposition method needs Power supply, and equipment is more complicated also.
Active carbon adsorption.On combustible support, destroy O by being adsorbed on
3, be actually O
3by the landfill leachate of active carbon filtering layer is housed, when burning consumes carbon at a slow speed, O
3decomposed.Absorption/decomposition is to utilize silica gel, molecular sieve to O
3absorption set characteristic, make O
3decompose, but after several times regeneration, the O of adsorbent
3decomposability is lowered.Although active carbon has the ability of strong adsorption, catalytic decomposition, research shows, O
3in decomposable process part mechanism be presented as activated carbon surface and constituent oxidized, the essence of reaction is O
3to the smoulder process of active carbon, its life-span and validity are difficult to ensure, can produce multiple accessory substance simultaneously
Catalytic decomposition.Most catalyst is all palladium, manganese and nickel metal oxide, sometimes catalyst cupport on carrier, as catalyst based in supported palladium on alumina particles.O
3catalytic decomposition can make O
3than decomposing sooner when the active carbon, but also exist catalyst easily poisoning, service time is short, price is high, production process produces the problems such as pollution.
Find by analysis, these above-mentioned methods respectively have pluses and minuses at present, and wherein catalytic decomposition is for O
3decomposition effect best, therefore whether we can be by further researchs, find a kind of O that better decomposes
3catalyst?
Suitable catalyst should be a kind of existing extremely strong adsorption capacity, can enrichment O
3, have again strong catalytic decomposition O
3ability, and homeostasis, is difficult for the material of loss.According to such principle, can select the sorbing materials such as zeolite as catalyst.
Zeolite is the silicon aluminate crystal of the well-regulated cage type of a class tool or pore passage structure, has unique pore passage structure and very large specific area, has the effects such as stronger adsorbing separation, ion-exchange, catalysis.But not treated zeolite being directly used in decomposed containing O
3waste gas, its capacity of decomposition is poor.
Decompose O by activated carbon catalysis
3gas is known, O
3decomposition under thermic condition is unusual the key link, if selected in catalyst, a kind of specific heat capacity is little, the material of quick heating should be able to be brought into play better catalysis thermic and decompose O
3effect.Find by the specific heat capacity table of looking into common material, the about 0.8kJ/kg DEG C of specific heat capacity of quartz sand, heats up relatively fast; And the main component of quartz sand is SiO
2, with O
3do not react, stable in properties.Just the specific area of quartz sand is little, is unsuitable for doing adsorbent.
Summary of the invention
The present invention is in order to solve above-mentioned problems of the prior art, and a kind of novel ozone decomposed composite catalyst and the preparation method of this composite catalyst are provided.This composite catalyst is taking zeolite and quartz sand as raw material, and makes after iron modification.This composite catalyst can be brought into play quartz sand intensification pyrogenicity, improves thermic and decomposes O
3effect, can bring into play again the effect of modified zeolite adsorption-decomposition function.
The present invention is carried on zeolite taking nano-hydroxy iron oxide as hardening agent, forms the catalyst that possesses stronger adsorption-decomposition function ability, and in conjunction with O
3decomposition mechanism and expansion result of study, determined taking decomposition heat as thermal source, is warming up to the decomposition approach of 60～75 DEG C.Composite catalyst is by the alkalization modified quartz sand of iron ion, and nano-hydroxy iron oxide modified zeolite forms, and forms O
3the multi-angle capacities of decomposition such as adsorption and enrichment, catalytic decomposition, thermic decomposition.
The present invention is achieved by the following technical solutions:
A kind of ozone decomposed composite catalyst is to be formed for 1:4～4:1 mixed preparing in mass ratio by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
Zeolite is carried out to iron modification (being specially nano-hydroxy iron oxide modified), can make zeolite to O
3there are stronger absorption, capacity of decomposition, can decompose O thereby zeolite is become
3catalyst.Quartz sand is carried out to iron modification (being specially iron ion alkalization modified) simultaneously, can try hard to improve quartz sand to O
3selective absorption capacity of decomposition, finally itself and modified zeolite are used jointly, thus form to O
3the composite catalyst of the multi-angle capacities of decomposition such as adsorption and enrichment, catalytic decomposition, thermic decomposition.
Further, this composite catalyst is in mass ratio for 1:1 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.Through experimental verification, in the time that nano-hydroxy iron oxide modified zeolite mixes for 1:1 in mass ratio with the alkalization modified quartz sand of iron ion, the composite catalyst making is to O
3assimilation effect best.
A kind of preparation method of ozone decomposed composite catalyst, comprise the preparation of nano-hydroxy iron oxide modified zeolite and the preparation of the alkalization modified quartz sand of iron ion, wherein, the preparation method of nano-hydroxy iron oxide modified zeolite comprises the steps: (1), is 1.2molL by concentration
-1iron salt solutions stir, in whipping process, adding concentration is 0.1molL
-1naOH solution, make pH value of solution reach 2.0～2.5, now form the nanocrystal of ferriferous oxide, and stable be distributed in (ferric hydroxide colloid) in colloidal dispersion, containing ferrum collosol; (2), zeolite is put into the rare HNO of pH value as 5 taking solid-liquid mass ratio 1:3
3in solution, after vibration 30min, slowly add in step (1), make containing ferrum collosol, make zeolite and be 1:1 containing the volume ratio of ferrum collosol, keep vibration 1hr, last centrifugal taking-up zeolite; (3), centrifugal after the zeolite taking out in step (2) is cleaned at least 3 times with pure water, and after 110 DEG C of oven dryings, then be placed in 400 DEG C of Muffle furnace roasting 2hr, finally make nano-hydroxy iron oxide modified zeolite; The quartz sand that the preparation method of the alkalization modified quartz sand of iron ion comprises the steps: (1), get after cleaning is placed in container, and adds pure water, and addition is that 4:5 adds by pure water and quartz sand mass ratio, and then adding concentration is 2.0molL again
-1naOH solution, addition is that 1:10 adds by NaOH solution and pure water volume ratio; (2), under 50 DEG C of conditions of water-bath, stir after 1hr, dropwise adding concentration is 2.0molL
-1iron salt solutions, until system pH=8～9, after vibration 30min, take out quartz sand, with after rinsed with deionized water, at 110 DEG C of oven dryings, cooling, finally make the alkalization modified quartz sand of iron ion.
As described in the background art, active carbon is decomposing O
3time, active carbon is oxidized, forms oxidisability and decomposes, its life-span and validity are difficult to ensure, can produce multiple accessory substance simultaneously and cause the secondary pollution of environment.Thereby suitable catalyst should be a kind of existing strong adsorption capacity, can enrichment O
3, catalytic decomposition O that again can be strong
3,, there is not the material of loss in and homeostasis.
Therefore, selected the conventional adsorbent of chromatographic aluminium oxide, lime, kaolin, silica gel, zeolite etc. (except carbon containing) to O
3test, although find that these materials are to eliminating O
3have certain effect, by the result concerning Exhaust measurement under the same terms but compared with also having very large gap active carbon, do not reach the requirement in the imagination, lime, kaolin hold very much easy dusting, and in zeolite, have the composition of aluminium oxide also to have the composition of silica gel, and they are all low for cost ratio, and stable, granularity is moderate, therefore finally selects the raw material of zeolite as composite catalyst of the present invention.But the catalytic effect of zeolite does not reach the requirement in the imagination, as shown in Figure 6.
Therefore, need to carry out certain modification to zeolite, the carrier using zeolite as modified absorbing material.Zeolite molecules formula Am [(AlO
2) x (SiO
2) y] n (H
2o), (wherein: A is the cations such as Ca, Na, K, Ba, Sr, m is cation number, n is water molecule number, x is Al atomicity, y is Si atomicity, (y/x) conventionally between 1～5, (x+y) be tetrahedral number in unit cell), it is the silicon aluminate crystal of the well-regulated cage type of a class tool or pore passage structure, have unique pore passage structure and large specific area, have the effects such as stronger adsorbing separation, ion-exchange, catalysis, be widely used in the field such as water treatment and chemical industry.
O
3a high electron density oxygen atom in the resonant structure of molecule shows strong elecrtonegativity; Al
3+, Fe
3+deng the cation with high electric charge, between them, should there is stronger binding ability.Bulanin etc. (1995) study O by Fourier transform infrared spectrometry
3absorption, and prove O
3form elemental oxygen at the lewis acid such as aluminium oxide, iron oxide Surface disintegration.Therefore, can select in principle the slaine such as iron, aluminium as modifier, but because containing aluminium oxide in zeolite, and the form of iron oxide is more stable, therefore selects oxide or the load of iron ion form of iron, and effect can be better, also more economical.
But because heat transfer and the particle of zeolite are less than normal, will produce gas by not smooth, local temperature is higher, conducts heat and the problem such as be not good at.Should be able to bring into play better if select less, the quick heating of specific heat capacity and material that can pay(useful) load iron in catalyst the effect that catalysis thermic decomposes.Therefore, find by the specific heat capacity table of looking into common material, the about 0.80J/ of specific heat capacity (kg DEG C) of quartz sand, less in non-metal solid, and the main component of quartz sand is SiO
2, with O
3do not react, stable in properties, the quartz sand adsorption rate after load iron can increase by 10 times.If the surface area of not load quartz sand is less, the adsorption effect of entirety will reduce.For this reason, quartz sand is carried out to the modification of iron ion alkalescence, can improve it to O
3selective absorption capacity of decomposition.
Confirm through experimental result, by load the zeolite of ferriferous oxide and composite catalyst that quartz sand forms to O
3decomposition efficiency all significantly improve.
Further, described iron salt solutions is FeCl
3solution, Fe (NO
3)
3solution or Fe
2(SO
4)
3solution.
In the preparation process of the alkalization modified quartz sand of described iron ion, the granularity of the quartz sand of use is 0.8～1.2mm, and porosity is 0.41.
Composite catalyst of the present invention forms with nano-hydroxy iron oxide modified zeolite and the common mixed preparing of the alkalization modified quartz sand of iron ion, has both brought into play quartz sand intensification pyrogenicity, improves thermic and decomposes O
3effect, brought into play again the effect of modified zeolite adsorption-decomposition function.In addition, it is high that composite catalyst of the present invention also has resolution ratio, and security is good, and self does not consume, long service life, and do not produce the advantages such as harmful substance.
Be below experiment related to the present invention, it should be noted that following experiment only plays illustrative effect to the present invention, does not do any restriction to the present invention:
1, the analysis of activated carbon catalysis ozone decomposition
1.1 materials and methods
1.1.1 material and instrument
Ozone generator, source of the gas is source of oxygen.
Infrared radiation thermometer.
Chromatography of ions Metrohm 820IC, Switzerland; These two Instrument measurings of elemental analyser Vario EL III(are measured for entrusting).
Decompose post, filling department divides caliber 18mm, the about 75mm of catalyst packing height; Three catalyst decomposes are processed post and are connected in series, loading catalyst 12g in every pillar.
Paniculate coal activated carbon (active carbon Co., Ltd of Shanxi Xinhua), washes removal surface powder with water, after washing, under the condition of 110 DEG C, dries; The basic parameter of active carbon, specific area 897m
2g
-1, micropore volume 0.43 cm
3g
-1, Penetrating curve>=54%, iodine number 850～1100mgg
-1, particle diameter is 2.0～2.5mm approximately, porosity 42%, intensity>=90%, ash content 5～18%.
Zeolite is the artificial particulate zeolites of SILVER REAGENT.
Quartz sand: granularity is 0.8-1.2mm, porosity 0.41.
It is pure that the reagent such as NaOH, iron chloride is analysis.
1.1.2 method
1.1.2.1 catalytic decomposition ozone approach
Catalytic decomposition O
3adopt three grades of decomposition post series connection, respectively decompose between post and connect with the silicone tube that can disassemble, and valve, flow measuring unit, device for absorbing tail gas etc. are set.Decompose testing arrangement connection diagram and see Fig. 1.Three grades of decomposition posts all adopt glass tube, can peg graft, and are convenient in observational study decomposition posts at different levels catalyst to O
3decomposition effect and correlated characteristic, as CO
2release Deng gas in tail gas and catalyst fever phenomenon etc.
O
3generator is selected and can be utilized the generator of source of oxygen as source of the gas.Be wherein 1.2～2.5Lmin as the oxygen flow of source of the gas
-1, flow, by flowmeter control, keeps stable relatively in test.O after decomposition experiment starts
3producing method for determination of amount is that every 15min is by O
3after being absorbed by KI solution, with iodometric determination, after calculating, get its mean value, as O in experimentation
3generating capacity (but O when only test starts and finishes in continuous decomposition experiment
3generating capacity, and get its mean value as O in experimentation
3generating capacity).Tail gas after catalytic decomposition enters the absorption bottle that KI solution is housed, and utilizes KI solution to absorb, detect, and after adding starch as without change color (becoming blue), shows O
3decomposition efficiency reaches 100%; Otherwise with the O in iodometric determination absorption liquid
3content.
1.1.2.2 variations in temperature
The mensuration of variations in temperature is according to decomposing testing process, during using first resolution process post along airflow direction from beginning contact catalyst, mark a site as thermometric site every 1.5cm, get altogether 5 sites as Fig. 2, orientate successively site a, site b, site c, site d, site e as, according to certain hour interval infrared radiation thermometer thermometric, operation continuously, mensuration 60min or longer time.When thermometric, require infrared radiation thermometer apart from site 2cm, measure in site vertical direction.
1.1.2.3 CO
2generation is measured
Catalyst is packed into and decomposed in post, dry 1hr at 110 DEG C, weigh.After connecting device by Fig. 1, open O
3generator, timing, tail gas is by 400mL 0.01molL
-1naOH solution absorb, after certain hour, change absorption liquid, in absorption liquid, pipette 5ml sample to 50ml colorimetric cylinder, be diluted to scale, to be measured.
CO
2generation is measured by TOC analyzer (Shimadzu), and contrasts the wherein difference of TC and IC, determine in absorption liquid, whether exist other forms of can absorbed carbonaceous material.
After finishing with experiment before experiment, respectively the resolution process post of having filled catalyst is dried to 1hr with 110 DEG C, weigh, calculate active carbon loss amount.
1.1.2.4 ion chromatography
O
3decomposable process is the same, with 0.01molL
-1naOH be absorption liquid, absorb the tail gas of different decomposition time period; Take off after absorption bottle with 1molL
-1hCl regulates pH to 7 left and right, with wherein anion-content of ion chromatography.
1.2 results of study and discussion
1.2.1 catalytic decomposition efficiency
Conjunctive decomposition testing arrangement, as Fig. 1, is processed the O of post by having filled the catalytic decomposition of active carbon
3air flow rate is 1.4～1.6Lmin
-1, O
3amount 7.8～9.8 mgmin
-1, by three grades of resolution process posts.After operating steadily, disconnect the pipeline after coagulation post, will pass into tail gas absorption bottle by the residual gas after coagulation post, measure wherein O
3residual volume is 0.38～0.43 mgmin
-1; Measure after decomposition situation, system is reconnected as Fig. 1, after operating steadily, disconnect series connection two stage treatment post, will pass into tail gas absorption bottle by the residual gas after coagulation post, measure and obtain O
3residual volume is 0.01～0.02 mgmin
-1; Decompose still completely not, now the corresponding time of staying is about 0.6～0.7Sec left and right.Measure after decomposition situation, system is reconnected as Fig. 1, after operating steadily, the O of tail gas after mensuration series connection tertiary treatment post
3residual volume has been reduced to 0 mgmin
-1.Continue operation decomposer, absorb three grades of cascade decompositions process the tail gas after post with liquor kalii iodide, move continuously 3～7hr, KI solution nondiscolouring in absorption bottle, utilizes O in iodometric titrationiodimetry titration test absorption liquid
3content, result shows O
3residual is 0, O
3resolution ratio reaches 100%, and said determination genus accumulative total absorbs result.This experimental provision and wherein O used are under these conditions described
3distintegrant decomposes respond well and stable.
1.2.2 resolution process column temperature changes
In catalytic decomposition process, the temperature of resolution process post raises gradually.By measuring, find, in system running, to heat up and mainly concentrate on first order resolution process post, and temperature rising speed in front 15min, maintaining afterwards higher temperature, temporal evolution is very little.As shown in Figure 3, reaction starts to 15min, the each site of first order resolution process post temperature all raises rapidly, and intensification order is substantially: c> site, b> site, a> site, site d> site e.Intensification foreground concentrates between site a, site b, and wherein first order resolution process column temperature is up to 65 DEG C of left and right.Before and after site a, site b, should be containing O
3o when gas contacts with distintegrant
3the position that content is the highest.Variations in temperature reduces afterwards, and the mensuration temperature on corresponding site tends towards stability.All the other two-stage resolution process column temperature are slightly improved between 27.9～30.1 DEG C than room temperature, substantially remain unchanged.
Heat up and mainly occur in O while contact with distintegrant
3near the higher position of content, these positions and near O
3decomposed rapidly, made follow-up distintegrant contact O
3concentration decline, along with contact O
3the minimizing of dosage, decomposition reaction (2O
3==3O
2) rate reduction, liberated heat reduces, and the difference of the intensification phenomenon of follow-up location site d and site e is not obvious, now O
3concentration also become very little.
1.2.3 the mass loss of resolution process post and active carbon constituent analysis
I have measured CO in resolution process post reaction front and back mass change, decomposed tail gas absorption liquid
2the output of generation and anion.
The quality of activated carbon of measuring in three grades of resolution process posts changes.Result shows, the active carbon in three grades of resolution process posts after cartalytic decomposition effect after a while has certain quality to reduce, as Fig. 4.In conjunction with the variations in temperature of front 15min with to three grades of resolution process posts decomposition efficiency explanation O step by step
3decomposition reaction mainly occur in first order resolution process post, explanation is simultaneously depleted as the active carbon of catalyst.
For catalytic decomposition O
3active carbon be coal mass active carbon, it is carried out to elementary analysis.Through determination of elemental analysis, without decompose O
3active carbon in the mass fraction of C be 81.23%, be essential element; Wherein also have 5.31% N and 9.72% O, other are as lower in S, Fe, Ca, P, K equal size.
TOC and ion chromatography result confirm, really contain CO in tail gas absorption liquid
2and NO
3 -.The two productive rate is the highest while being initial decomposition, after along with decline running time gradually; Show O
3occur to react with activated carbon substrate, caused the variation of active carbon structure and the minimizing of quality, and produced NO
xharmful substance, as Fig. 5, causes secondary pollution to environment.
In system, heat generation mainly comes from oxidation and the O of C
3self decomposes.Incipient stage, the oxidized heat release of active carbon, simultaneously with O
3self decomposition caused heat release, resolution process column temperature raises fast.Intensification causes O
3self decomposition ratio increases, and system entirety thermal discharge declines.Work as O
3self decomposes with active carbon by O
3between oxidation, form certain proportion, the two reaches stability, and temperature is basicly stable, no longer obviously rises.In the time that the variation of temperature tends towards stability gradually, CO
2generation speed decline simultaneously, show active carbon structural element oxidation rate decline; And to keep same O
3resolution ratio, O
3self thermic disassemble to start and wave Main Function.
Active carbon is studied in detail and draws to draw a conclusion:
(1) decomposition mechanism is divided into three parts: one is activated carbon catalysis O
3be decomposed into O
2, active carbon is brought into play the effect of catalyst therein, and mechanism is mainly that the strong adsorption ability of active carbon causes local location O
3enrichment, decomposition; Its two active carbons and O
3react, destroyed activated carbon surface structure and group, cause the decline of activated carbon catalysis decomposability; It three is O
3the heat discharging while being decomposed to form oxygen, carbon dioxide and accessory substance with above-mentioned two kinds of mechanism causes decomposition region temperature to raise, and further promotes O
3decompose.
(2) O
3oxidation Decomposition and self decomposable process be all accompanied by the variation of temperature, temperature can be used as O
3easy and the important indication parameter decomposing.Decompose near the strong space-time site of Shaoxing opera, variations in temperature is also more remarkable.
(3) activated carbon catalysis decomposes O
3an exothermic process, thermal discharge and O
3concentration, catalyst property, air flow rate, speed, structure of reactor etc. are relevant.Under certain conditions, the temperature that heat release causes presents certain spatial and temporal distributions, can pass through usefulness and security, the stability etc. of this rule Study of Catalyst, can also be used for the design of resolution process device.
(4) activated carbon catalysis decomposes O
3in process, produce again CO
2and nitrogen oxide etc., cause the loss of catalyst and the secondary pollution of environment.
2, iron modified zeolite (being nano-hydroxy iron oxide modified zeolite, lower same) decomposes O
3compliance test result
Get 60g in the zeolite of iron modification is filled to the glass tube that caliber is 18mm, O
3flow is 8～15mgmin
-1, gas flow 1.5 Lmin
-1, time of staying 0.96s, tail gas detects residue O with KI absorption liquid
3amount, system is moved 5hr, O continuously
3decomposition efficiency reaches more than 99.5%.With unmodified zeolite filling, resolution ratio is between 85～92% equally.
Get the glass tube that bore is 30mm, by the zeolite after modification and all fillings respectively of unmodified zeolite, tail gas detects O with the titration of KI absorption liquid
3content, O
3flow, containing O
3gas flow, the time of staying, system operation time, decomposition O
3effect is in table 1:
Table 1 catalytic decomposition post decomposes O
3effect
| Catalyst | O 3 mg·min -1 | Flow Lmin -1 | Time of staying s | Running time hr | Resolution ratio % |
| Zeolite | 4.5～7.9 | 1.6 | 1.6 | 3 | 91.7 |
| Modified zeolite | 5.7～9.2 | 1.6 | 1.6 | 5 | 100 |
| Modified zeolite | 4.7～8.2 | 1.6 | 1.6 | 5 | 100 |
| Zeolite | 6.9～9.7 | 2.8 | 0.9 | 3 | 87 |
| Modified zeolite | 7.2～8.7 | 2.8 | 0.9 | 3 | 99.4 |
| Modified zeolite | 6.3～9.5 | 2.8 | 0.9 | 2 | 99.3 |
The decomposer overall operation time that modified zeolite is loaded exceedes 25hr, and effect is still stable, decomposes O
3efficiency is maintaining between 99～100%.By tail gas is carried out to alkali lye (0.01molL
-1naOH) absorb, absorption liquid is carried out to chromatography of ions anion analysis, do not detect the anion such as nitrate anion, nitrite anions, sulfate radical, chlorion, fluorine ion, phosphate radical.After this example shows modification, zeolite is to O
3capacity of decomposition obviously strengthens, and has no and produces pernicious gas pollutant, stable performance.
3, composite catalyst of the present invention decomposes O
3compliance test result
(be the alkalization modified quartz sand of iron ion by dry iron modified zeolite and iron Modified Quartz Sand, lower with) respectively taking mass ratio as 1:4,1:2,1:1,2:1,4:1 be mixed and made into four kinds of different composite catalysts and be filled in resolution process post, packed height 80mm.
Contrast independent iron modified zeolite and composite catalyst two class catalyst to O
3catalytic decomposition efficiency.Exhaust flow is 1.6～1.8Lmin
-1, O
3content 5～6.5mgm
-3.In glass tube (caliber 18mm, long 330mm) resolution process device, load respectively composite catalyst and iron modified zeolite, more than loading height 200mm.Tail gas, through resolution process device, detects O to tail gas with the titration of KI absorption liquid
3content, clearance is always 100%.Tail gas is carried out to alkali lye (0.01molL
-1naOH) absorb, absorption liquid is carried out to chromatography of ions anion analysis, do not detect the anion such as nitrate anion, nitrite anions, sulfate radical, chlorion, fluorine ion, phosphate radical.Install the O after different proportion mixed catalyst additional
3decomposition efficiency, as shown in Figure 6.(explain: improving throughput and be equivalent to the corresponding minimizing time of staying, is exactly to reduce in the reaction time, and decrease in efficiency is naturally, reasonably)
So from Fig. 6 result, when iron modified zeolite and iron Modified Quartz Sand proportioning are 1:1, resolution ratio can reach 99.8%, absorption efficiency is best, and therefore, the best proportioning of this composite catalyst is 1:1, and the proportioning of 1:1 is used for to experiment below.
Monitoring along variations in temperature in journey pipe as shown in following table 2, table 3, table 4:
Table 2 is filled the resolution process device of unmodified zeolite along journey and time variations in temperature
The resolution process device of the filling-modified zeolite of table 3 is along journey and time variations in temperature
The resolution process device of table 4 filled composite catalyst is along journey and time variations in temperature
Site a～e be respectively by inlet end play 1,3,5,7,10cm place.
Early-stage Study shows, O
3decomposable process is accompanied by variations in temperature, is exactly the most violent space-time site of decomposition near the larger space-time site of variations in temperature.Contrast unmodified zeolite and modified zeolite decomposition O according to space-time site variations in temperature
3catalytic capability (table 2, table 3) visible, unmodified zeolite variations in temperature is comparatively slow, and position range is larger, still after tens minutes, reaches 38 DEG C at 7cm place; Before after modification, zeolite range of temperature mainly concentrates on 5cm place, and heat up rapidly.In conjunction with decomposing absorption liquid O early stage
3determination data, shows that modified zeolite decomposes O
3usefulness significantly improve.
The two decomposes O contrast modified zeolite and composite catalyst
3catalytic capability (table 3, table 4) visible, the part significantly heating up in the resolution process post that composite catalyst is filled was mainly before 5cm, and the intensification of 5cm place is still very obvious in the resolution process post that modified zeolite is filled, show that composite catalyst is compared with modified zeolite catalytic decomposition O
3ability is strong.In addition, the resolution process post maximum temperature that composite catalyst is filled is high compared with modified zeolite, be respectively 72.8 DEG C and 67.9 DEG C, and environment temperature is respectively 25.1 DEG C and 25.8 DEG C, shows that composite catalyst catalytic decomposition ability is strong.
Brief description of the drawings
Fig. 1 is the Experimental equipment of activated carbon catalysis ozone decomposition.
Fig. 2 is the site signature on resolution process post.
Fig. 3 is CO
2produce speed and temperature change in time and space relation.
Fig. 4 is quality of activated carbon variation diagram in resolution process post.
Fig. 5 be NOx output over time.
Fig. 6 is that different catalysts is to O
3resolution ratio figure.
In figure: 1-oxygenerator, 2-ozone generator, 3-flow controller, 4-catalytic decomposition one-level, 5-catalytic decomposition secondary, three grades of 6-catalytic decomposition, 7-absorption liquid, alpha-position point a, b-site b, c-site c, d-site d, e-site e.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention is done to description further:
Embodiment 1
A kind of ozone decomposed composite catalyst is in mass ratio for 1:4 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
The preparation method of this ozone decomposed composite catalyst, comprise the preparation of nano-hydroxy iron oxide modified zeolite and the preparation of the alkalization modified quartz sand of iron ion, wherein, the preparation method of nano-hydroxy iron oxide modified zeolite comprises the steps: (1), is 1.2molL by concentration
-1feCl
3solution stirs, and in whipping process, adding concentration is 0.1molL
-1naOH solution, make pH value of solution reach 2.0～2.5, now form the nanocrystal of ferriferous oxide, and stable being distributed in colloidal dispersion, containing ferrum collosol; (2), zeolite is put into the rare HNO of pH value as 5 taking solid-liquid mass ratio 1:3
3in solution, after vibration 30min, slowly add in step (1), make containing ferrum collosol, make zeolite and be 1:1 containing the volume ratio of ferrum collosol, keep vibration 1hr, last centrifugal taking-up zeolite; (3), centrifugal after the zeolite taking out in step (2) is cleaned at least 3 times with pure water, and after 110 DEG C of oven dryings, then be placed in 400 DEG C of Muffle furnace roasting 2hr, finally make nano-hydroxy iron oxide modified zeolite; The preparation method of the alkalization modified quartz sand of iron ion comprises the steps: (1), gets granularity is the quartz sand that 1.1mm, porosity are 0.41, cleaning is placed in container, and add pure water, and addition is that 4:5 adds by pure water and quartz sand mass ratio, then adding concentration is 2.0molL again
-1naOH solution, addition is that 1:10 adds by NaOH solution and pure water volume ratio; (2), under 50 DEG C of conditions of water-bath, stir after 1hr, dropwise adding concentration is 2.0molL
-1feCl
3solution, until quartz sand is taken out after vibration 30min in system pH=8～9, with after rinsed with deionized water, at 110 DEG C of oven dryings, cooling, finally makes the alkalization modified quartz sand of iron ion.
Embodiment 2
A kind of ozone decomposed composite catalyst is in mass ratio for 1:2 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
The preparation method of this ozone decomposed composite catalyst is identical with the preparation method in embodiment 1, and difference is: the iron salt solutions using is Fe
2(SO
4)
3solution, the quartz sand size using is 0.9mm.
Embodiment 3
A kind of ozone decomposed composite catalyst is in mass ratio for 1:1 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
The preparation method of this ozone decomposed composite catalyst is identical with the preparation method in embodiment 1, and difference is: the quartz sand size using is 1.0mm.
Embodiment 4
A kind of ozone decomposed composite catalyst is in mass ratio for 2:1 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
The preparation method of this ozone decomposed composite catalyst is identical with the preparation method in embodiment 1, and difference is: the iron salt solutions using is Fe (NO
3)
3solution, the quartz sand size using is 0.8mm.
Embodiment 5
A kind of ozone decomposed composite catalyst is in mass ratio for 4:1 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
The preparation method of this ozone decomposed composite catalyst is identical with the preparation method in embodiment 1, and difference is: the iron salt solutions using is Fe (NO
3)
3solution, the quartz sand size using is 1.2mm.
Claims (2)
1. an ozone decomposed composite catalyst, is characterized in that: this composite catalyst is to be formed for 1:4～4:1 mixed preparing in mass ratio by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion; Wherein, the preparation method of nano-hydroxy iron oxide modified zeolite comprises the steps: (1), is 1.2molL by concentration
-1iron salt solutions stir, in whipping process, adding concentration is 0.1molL
-1naOH solution, make pH value of solution reach 2.0～2.5, now form the nanocrystal of ferriferous oxide, and stable being distributed in colloidal dispersion, containing ferrum collosol; (2), zeolite is put into the rare HNO of pH value as 5 taking solid-liquid mass ratio 1:3
3in solution, after vibration 30min, slowly add in step (1), make containing ferrum collosol, make zeolite and be 1:1 containing the volume ratio of ferrum collosol, keep vibration 1hr, last centrifugal taking-up zeolite; (3), centrifugal after the zeolite taking out in step (2) is cleaned at least 3 times with pure water, and after 110 DEG C of oven dryings, then be placed in 400 DEG C of Muffle furnace roasting 2hr, finally make nano-hydroxy iron oxide modified zeolite; The quartz sand that the preparation method of the alkalization modified quartz sand of iron ion comprises the steps: (1), get after cleaning is placed in container, and adds pure water, and addition is that 4:5 adds by pure water and quartz sand mass ratio, and then adding concentration is 2.0molL again
-1naOH solution, addition is that 1:10 adds by NaOH solution and pure water volume ratio; (2), under 50 DEG C of conditions of water-bath, stir after 1hr, dropwise adding concentration is 2.0molL
-1iron salt solutions, until system pH=8～9, after vibration 30min, take out quartz sand, with after rinsed with deionized water, at 110 DEG C of oven dryings, cooling, finally make the alkalization modified quartz sand of iron ion; Described iron salt solutions is FeCl
3solution, Fe (NO
3)
3solution or Fe
2(SO
4)
3solution; In the preparation process of the alkalization modified quartz sand of described iron ion, the granularity of the quartz sand of use is 0.8～1.2mm, and porosity is 0.41.
2. a kind of ozone decomposed composite catalyst according to claim 1, is characterized in that: this composite catalyst is in mass ratio for 1:1 mixed preparing forms by nano-hydroxy iron oxide modified zeolite and the alkalization modified quartz sand of iron ion.
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|---|---|---|---|---|
| CN1465427A (en) * | 2002-07-02 | 2004-01-07 | 中国科学院生态环境研究中心 | Catalyzing method for eliminating O3 and simutaneously eliminating O3 and CO |
| CN102557062A (en) * | 2012-01-15 | 2012-07-11 | 山西大学 | Modified zeolite for degrading ozone-containing waste gas and preparation method for modified zeolite |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1465427A (en) * | 2002-07-02 | 2004-01-07 | 中国科学院生态环境研究中心 | Catalyzing method for eliminating O3 and simutaneously eliminating O3 and CO |
| CN102557062A (en) * | 2012-01-15 | 2012-07-11 | 山西大学 | Modified zeolite for degrading ozone-containing waste gas and preparation method for modified zeolite |
Non-Patent Citations (1)
| Title |
|---|
| 《Decomposition of ozone on a silver catalyst》;Seiichiro Imamura etal.;《ind. eng. chem. res.》;19911231;第30卷(第10期);218页第3-4段 * |
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