CN103360346A - Method for preparing ethylene oxide by catalyzing ethylene oxidation via high-selective silver catalyst - Google Patents
Method for preparing ethylene oxide by catalyzing ethylene oxidation via high-selective silver catalyst Download PDFInfo
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Abstract
The invention provides a method for preparing an ethylene oxide by catalyzing ethylene oxidation via a high-selective silver catalyst, wherein the high-selective silver catalyst is fresh or is used during the rerunning after shut-down or the selectivity of which does not reach an expected value during the normal running of a device. According to the method, by controlling a certain amount of ethane to exist in an ethylene oxidation reaction gas and enabling the ethane concentration to be increased and then decreased within the range of 0 to 2.0mol% or 0.1 to 1.5mol%, the ethylene oxide is prepared. As the method is used, under the conditions that the service life of the high-selective silver catalyst is not shortened and the initial reaction temperature is not increased, the initial selectivity of the high-selective silver catalyst is improved rapidly; and the reaction temperature at the time of the appearing of the highest selectivity of the high-selective silver catalyst is decreased, i.e., the activity of the silver catalyst is improved by adding the ethane. In addition, a catalytic reaction of the high-selective silver catalyst can be carried out for a long time in a high-selective state, so that the average selectivity of the high-selective silver catalyst is improved.
Description
Technical field
The present invention relates to a kind of method of highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, be specifically related to the method that highly selective silver catalyst selectivity that a kind of quick raising oxidation of ethylene epoxy ethane optionally just using in method and a kind of oxidation of ethylene device with the highly selective silver catalyst initial stage significantly promotes.
Background technology
Direct oxidation of ethylene to mainly generates oxyethane (EO) under the silver catalyst effect, side reaction occurs simultaneously generate carbonic acid gas and water etc., and wherein activity, selectivity and stability are the main performance index of silver catalyst.Required temperature of reaction when so-called activity refers to that process for ethylene oxide production reaches certain reaction load; Temperature of reaction is lower, and the activity of catalyzer is higher.Conversion of ethylene became the ratio of the total reaction mole number of the mole number of oxyethane and ethene during so-called selectivity referred to react.So-called stability then is expressed as the fall off rate of activity and selectivity, and the fall off rate more stability of small catalyst is better.The silver catalyst that uses high reactivity, highly selective and have good stability in the process of oxidation of ethylene production oxyethane can be increased economic efficiency greatly, and the silver catalyst of therefore making high reactivity, highly selective and good stability is a main direction of silver catalyst research.But the performance of silver catalyst has the important relationship except composition and the preparation method with catalyzer, and also the use technique with catalyzer has important relationship.
The direct oxidation of ethylene to epoxy ethane is divided into high reactivity silver catalyst, middle highly selective silver catalyst and highly selective silver catalyst three classes with silver catalyst.The initial stage selectivity of high reactivity silver catalyst is 80-81mol%, and latter stage, selectivity was 76-78mol%, and space-time yield can reach EO/ hour * of 280 grams and rise catalyzer; The initial stage selectivity of middle highly selective silver catalyst is 81-85mol%, and highly selective is 85-86mol%, and latter stage, selectivity was 80-82mol%, and space-time yield can reach EO/ hour * of 200-280 gram and rise catalyzer; The initial stage selectivity of highly selective silver catalyst is 82-85mol%, and highly selective is 87-92mol%, and latter stage, selectivity was 82-84mol%, and space-time yield can reach EO/ hour * of 160-220 gram and rise catalyzer.In general, middle highly selective silver catalyst and highly selective silver catalyst are referred to as efficient silver catalyst.
Constantly surging along with oil price, the development trend of ethylene oxide production is to use high-selective ethylene epoxidation reaction silver catalyst, it obviously reduces with respect to the ethene material consumption of traditional high activity epoxidation catalyst.Yet for a given ethylene oxide yield, high-selectivity catalyst need to use the temperature of reaction higher than high activated catalyst, and its catalyst activity changing down is also very fast.Therefore, for activity, selectivity and the stability of taking into account catalyzer, in these years each large silver catalyst research company not only carries out unremitting effort at carrier and preparation thereof, also oxirane production technology and equipment is improved, to give full play to the usefulness of silver catalyst.
The highly selective silver catalyst is in the starting stage that is used for epoxidation process, and catalyzer need experience one so-called " break-through phase "; In this stage (being generally driving rear more than 1 year), selectivity of catalyst is very low, even using reaction control agent also is like this, in commercial start-up, need to adjust for a long time just can make reaction can catalyzer than the highly selective level under move.For this reason, the catalyst research personnel have carried out lot of experiments research to the starting method at catalyst runs initial stage.
In recent years, bibliographical information some improve highly selective silver catalyst initial stages Technology optionally.Patent EP1517751A2 and Chinese patent application 03815308.4 disclose and a kind ofly can improve high-selectivity catalyst initial stage starting method optionally: be higher than under 250 ℃ at catalyst temperature, make the loading type highly selective epoxidation catalyst that contains 0.19g silver at the most at every square metre of carrier surface and contain the oxygen raw material and contact, 150 hours at the most time length, reduce subsequently catalyst temperature to the highest 250 ℃, and catalyzer is contacted with the raw material that contains alkene and oxygen, can significantly improve the initial stage selectivity of highly selective silver catalyst.US20070670325 and CN101410178A propose to carry out first pyroprocessing before catalyzer passes into the reaction raw materials gas mixture, pass into feed oxygen at least 5 minutes under 350 ℃.This patent application is claimed, after the catalyzer process oxygen pyroprocessing, has increased significantly the initial selectivity of catalyzer; And show that the catalyzer physical strength strengthens, and has improved catalytic performance.Chinese patent application 200680012785 provides a kind of method of producing oxyethane: in the presence of water and halogen contained compound, ethene is contacted with silver catalyst with oxygen, the document claim catalyst performance be improved significantly.US4874879 and US5155242 propose to make catalyzer stand the Organohalogen compounds pre-soak period in the driving scheme of oxyethane: be lower than under the temperature of reactor service temperature, in the presence of Organohalogen compounds, make conventional catalyzer stand a pre-soak period.The method of this processing catalyzer can reduce the generation of carbonic acid gas.With Organohalogen compounds pre-soakings highly selective silver catalyst, and contact with the unstripped gas that does not contain organic halid unstripped gas or contain the lower concentration Organohalogen compounds among the CN03815312.The method makes production oxyethane have highly selective.In US20090082584 and US7553980, proposed to relate to a process that starts the highly selective silver catalyst: the startup of highly selective silver catalyst is the activity of controlling silver catalyst by passing into high concentration carbon dioxide.In other words, the method for this invention is when the transformation efficiency of ethene in the control reactor requires to improve temperature of reaction, realizes by gas concentration lwevel in the raising charging.
Above-mentioned these novel methods not only form from adjusting reaction gas, and start with to improve the initial performance of oxyethane highly selective silver catalyst from silver catalyst initial stage driving technique.But these methods are also very limited to the improvement that the activity and selectivity of highly selective silver catalyst brings, therefore, this area still needs to be beneficial to improve the initial reaction performance of efficient silver catalyst to adopting the highly selective silver catalyst to be improved by the technique of oxidation of ethylene epoxy ethane.
In addition, for the highly selective silver catalyst that is just using in the oxidation of ethylene device, improve in the prior art its optionally method generally be to realize by adding a large amount of inhibitor, as by adding a large amount of pentanes and temperature of reaction being brought up to 240 ℃ or above ability fast so that selectivity is increased to 88%.
In recent years, bibliographical information some improve optionally Technology of highly selective silver catalysts.Provide a kind of method of producing oxyethane such as Chinese patent application 200680012785: in the presence of water and halogen contained compound, ethene is contacted with silver catalyst with oxygen, catalyst performance be improved significantly.US4874879 and US5155242 propose to make catalyzer stand the Organohalogen compounds pre-soak period in the driving scheme of oxyethane: be lower than under the temperature of reactor service temperature, in the presence of Organohalogen compounds, make conventional catalyzer stand a pre-soak period.The method of this processing catalyzer can reduce the generation of carbonic acid gas.With Organohalogen compounds pre-soakings highly selective silver catalyst, and contact with the unstripped gas that does not contain organic halid unstripped gas or contain the lower concentration Organohalogen compounds among the CN03815312.The method makes production oxyethane have highly selective.
The improvement that above-mentioned these methods are brought the selectivity of highly selective silver catalyst is also very limited, therefore, this area still needs to be beneficial to improve fast the selectivity of highly selective silver catalyst to adopting the highly selective silver catalyst to be improved by the technique of oxidation of ethylene epoxy ethane.
Summary of the invention
The invention provides a kind of method of highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, wherein the highly selective silver catalyst be fresh or stop after again the drive highly selective silver catalyst that uses, ethylene concentration is 20-40mol% in ethylene oxidation reactions gas, oxygen concentration is 6-8.5mol%, gas concentration lwevel is＜2mol%, the concentration of inhibitor is regulated in 0.2-2ppmv, and the concentration of ethane increases afterwards first in 0-2.0mol% and subtracts, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-250 ℃.
In a concrete embodiment, in reaction unit, pack into after described highly selective silver catalyst and the running of driving, at first progressively add ethane in the reaction gas and its concentration is controlled at a low concentration in the 0-2.0mol%, then be increased to a higher concentration and keep this ethane concentration until reaction reaches expection ethane concentration is reduced during selectivity again, and in the scope of 0.2-2ppmv appropriate rising inhibitor concentration.Wherein, preferred scheme is at first progressively to add ethane and its concentration is controlled at 0-1.0mol% in reaction gas, more preferably 0-0.8mol%; Then device reach when load expection ethane concentration is raise for 0.2-2.0mol%, more preferably 0.4-1.2mol% and when keeping this concentration to reaction to reach the expection selectivity again with reaction gas in ethane concentration be reduced to 0-0.8mol%, more preferably 0.2-0.6mol%.
In such scheme, it is 2～20 days, preferred 7～10 days that described device reaches when load expection apart from the runtime of driving, described expection selectivity is 87～93mol%, preferred 88～91mol%, described reaction reach expection during selectivity apart from the runtime of driving be 20 days～6 months, preferred 1～2 month.Appropriate rising inhibitor concentration in the scope at 0.2-2ppm when reaction reaches expection to reduce ethane concentration during selectivity, so far, for the initial stage that promotes the highly selective silver catalyst optionally scheme finished enforcement.
In the above-described embodiment, use nitrogen oxygen concentration when causing steady gas to be 6-7mol%, use methane oxygen concentration when causing steady gas to be 7.5-8.5mol%.Described oxidizing reaction temperature is for being preferably 190-240 ℃, more preferably 200-230 ℃.
The present invention also provides a kind of method of highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, wherein the highly selective silver catalyst is to run well in the device but selectivity does not reach the catalyzer of desired value, ethylene concentration is 20-40mol% in ethylene oxidation reactions gas, oxygen concentration is 6-8.5mol%, gas concentration lwevel is＜2mol%, the concentration of inhibitor is regulated in 0.2-2ppmv, adding ethane in the reaction gas, to make its concentration be 0.1-1.5mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-260 ℃; When in reaction gas, adding ethane, before or after will install 5-20 ℃ of interior reaction temperature reduction; When reaching the anticipation reaction selectivity, in 0.2-2ppmv, suitably improve inhibitor concentration, in the 0.1-1.5mol% scope, suitably reduce simultaneously ethane concentration.
In a preferred embodiment, described anticipation reaction selectivity is 87～93mol%, and described is 3～20 days apart from adding the ethane time when reaching the anticipation reaction selectivity.More preferably described anticipation reaction selectivity is 88～91mol%, and described is 7～10 days apart from adding the ethane time when reaching the anticipation reaction selectivity.
In the present invention, preferably when in reaction gas, adding ethane, before or after will install 6-15 ℃ of interior reaction temperature reduction, more preferably reduce 8-10 ℃.
In the present invention, preferably adding ethane in the reaction gas, to make its concentration be 0.2-1.2mol%, reduces ethane concentration to 0.1-0.8mol% when reaching the anticipation reaction selectivity.More preferably adding ethane in the reaction gas, to make its concentration be 0.4-0.8mol%, reduces ethane concentration to 0.2-0.4mol% when reaching the anticipation reaction selectivity.
Among the present invention, use nitrogen oxygen concentration when causing steady gas to be 6-7mol%, use methane oxygen concentration when causing steady gas to be 7.5-8.5mol%; And described inhibitor is monochlorethane and/or ethylene dichloride.In addition, oxidizing reaction temperature is 190-250 ℃ described in preferred the present invention, more preferably 200-240 ℃.In the present invention, running well in the preferred described oxidation of ethylene device but selectivity does not reach the catalyzer of desired value is duration of service of described highly selective silver catalyst to have reached 1～12 month after the device running at full capacity, more preferably 3～10 months.
In the above-mentioned two schemes of the present invention, described highly selective silver catalyst is that the initial stage selectivity is greater than 82mol%; Highly selective is preferably greater than 87mol% greater than 86mol%; Latter stage, selectivity was greater than 82mol%, was preferably greater than 84mol%; And space-time yield is the catalyzer of EO/ hour * liter of 160-280 gram.Wherein said initial stage selectivity refers to that silver catalyst brings into use the average selectivity to rear 1 month of the full load that reaches the device technique requirement, and described latter stage, selectivity referred to last 2～3 months average selectivity that silver catalyst uses; Be generally 2～3 years the work-ing life of whole highly selective silver catalyst.
By the reaction gas of oxidation of ethylene epoxy ethane, it usually comprises ethene, oxygen, causes steady gas and inhibitor.As causing steady gas, to its objective is that the concentration of ethene and oxygen operates in the reaction gas in order keeping in limits of explosion, and to cause steady gas itself and do not participate in reaction that reaction is not had negatively influencing.Cause steady gas and be generally nitrogen, methane or its mixture: methane is conducive to improve oxygen content and the molten value of air heat in the unstripped gas, to reacting favourable; But some producer is because the processing condition restriction uses nitrogen as causing steady gas.The purpose that adds inhibitor in the reaction gas is in order to suppress the active of silver catalyst and to improve selectivity; For the highly selective silver catalyst, inhibitor has the effect that improves silver catalyst stability simultaneously.Inhibitor generally includes monochlorethane, ethylene dichloride or its mixture.When reaction gas recycles, also can accumulate a certain amount of carbonic acid gas in the reaction gas, the increase of carbonic acid gas can affect the stability of efficient silver catalyst.In addition, in factory's use procedure, usually also can there be some foreign gases in the initial action gas, such as hydrogen, ethane, argon gas.Argon gas is rare gas element, does not participate in reaction.In the prior art, it is generally acknowledged that the ethane content rising can cause that the active rising of high reactivity silver catalyst and selectivity decline to a great extent, when ethane content reaches certain value (as greater than 0.7%) reaction very exothermic and selectivity aggravation are descended.Therefore, generally do not allow the impurity ethane of high density in the ethylene epoxidizing process, to occur in the prior art, generally the concentration of ethane in reaction gas can be controlled at 0.5mol% and not change during whole catalyst life with interior and its concentration.But, in the present invention, for fresh or stop after again the drive highly selective silver catalyst that uses, even at the initial stage of adding ethane (as reach device load before), when the activity that oxidation of ethylene prepares oxyethane significantly promoted, its selectivity of product obvious decline can not occur yet.Ethane can bring very significantly beneficial effect as highly selective silver catalyst initial stage promotor optionally.In addition, in the present invention, for the highly selective silver catalyst that is just using in the oxidation of ethylene device, by adding first certain density ethane, after reaching the expection selectivity, reducing again ethane concentration, the highly selective silver catalyst is largely increased fast to the selectivity of oxyethane, and the reduction value of catalyst activity is also in acceptable scope.
In one embodiment of the invention, described highly selective silver catalyst comprise carrier with and the following component of upper deposition, silver-colored activeconstituents; The rhenium auxiliary agent; Randomly, the coassist agent of rhenium auxiliary agent; Randomly, alkali metal promoter; Randomly, base earth metal promoter.The highly selective silver catalyst that the present invention uses is preferably composed as follows, and based on the gross weight of highly selective silver catalyst, silver content is counted the 1-30 % by weight with silver element, is preferably the 10-29 % by weight; And/or rhenium content counts 5ppm-2500ppm with the rhenium element, is preferably 10ppm-1500ppm; If and/or the coassist agent of rhenium auxiliary agent exists, its amount is counted 5ppm-1000ppm with this coassist agent element, is preferably 10ppm-500ppm; If and/or alkali metal promoter exists, its amount is counted 5ppm-2000ppm with alkali metal, is preferably 10ppm-1500ppm; If and/or base earth metal promoter exists, its amount is counted 5ppm-2000ppm with alkali earth metal, is preferably 10ppm-1200ppm.
As the silver of activeconstituents, it both can exist with argent, also can exist with silver compound.As silver compound, can mention silver suboxide, Silver Nitrate and/or silver oxalate.As the rhenium auxiliary agent, it both can exist with rhenium metal, also can exist with rhenium compound.As rhenium compound, can mention oxide compound, perrhenic acid, the perrhenate of rhenium, or its mixture, preferred perrhenic acid and perrhenate, such as perrhenic acid, perrhenic acid caesium, ammonium perrhenate or its mixture etc.As the coassist agent of rhenium auxiliary agent, it can be to be selected from one or more elements in lower group or the compound of this element: chromium, molybdenum, tungsten, boron, cerium, sulphur and manganese.As alkali metal promoter, it can be to be selected from one or more metals in lithium, sodium, potassium, rubidium and the caesium or the compound of this metal, is preferably lithium, potassium or caesium or its compound.As base earth metal promoter, it can be to be selected from one or more metals in magnesium, calcium, strontium and the barium or the compound of this metal, is preferably barium or strontium or its compound.
As mentioned above, highly selective silver catalyst of the present invention advantageously is loaded catalyst.As the carrier that is suitable for this catalyzer, it can be any carrier that is suitable for silver catalyst, can mention various oxide carriers or composite oxide carrier to this, for example silicon oxide, aluminum oxide (such as Alpha-alumina), aluminium oxide-silicon oxide composite oxide carrier also have zeolite, activated carbon etc. in addition.
Being suitable for highly selective silver catalyst of the present invention can be any highly selective silver catalyst.This catalyzer is both commercially available, also can prepare according to methods known in the art.For example, can be used for the method preparation that highly selective silver catalyst of the present invention can be by may further comprise the steps: the first step, with the solution impregnating carrier of the coassist agent of the silver compound that contains q.s, organic amine, rhenium auxiliary agent, optional rhenium auxiliary agent, optional alkali metal promoter and optional base earth metal promoter; Second step, the elimination steeping fluid; And the 3rd the step, in air or rare gas element, second step gained carrier is activated, make efficient silver catalyst.
Above-mentioned silver compound can prepare any silver compound that oxyethane is used silver catalyst by ethene for being suitable for.The present invention preferably uses silver suboxide, Silver Nitrate and/or silver oxalate.The add-on of silver compound in steeping fluid should be enough to make argentiferous 1-30 % by weight in the silver catalyst of final preparation, preferred 10-29 % by weight, based on total catalyst weight in silver atoms.
Above-mentioned organic amine compound can be for being suitable for preparing any organic amine compound of ethylene oxide silver catalyst, as long as this organic amine compound can form argent-amine complex with silver compound.For the purpose of the present invention, preferably use pyridine, butylamine, quadrol, 1,3-propylene diamine, thanomin or its mixture, for example mixture of quadrol and thanomin.
Except silver compound, organic amine, rhenium auxiliary agent, optional alkali metal promoter and optional base earth metal promoter, can also add the coassist agent of rhenium auxiliary agent, with activity, selectivity and the stability of further improvement gained silver catalyst in the dipping solution.The coassist agent of rhenium auxiliary agent can be the compound of arbitrary transition metal in the periodic table of elements (for example chromium, molybdenum, tungsten, boron, cerium and manganese), or the mixture of several transistion metal compounds, oxygen acid and the salt thereof of preferred group vib and VIIB family element, for example wolframic acid, ammonium tungstate, wolframic acid caesium, molybdic acid, ammonium molybdate or its tetrahydrate, ammonium metawolframate, Cerium disulfate tetrahydrate (Ce (SO
4)
24H
2O) etc.As the coassist agent of rhenium auxiliary agent, can also be sulphur.The coassist agent of rhenium auxiliary agent, if use, its consumption should so that in the final catalyzer coassist agent of rhenium auxiliary agent be preferably 10ppm-500ppm, based on the gross weight of efficient silver catalyst take the weight content of this coassist agent metallic element as 5ppm-1000ppm.The coassist agent of rhenium auxiliary agent can be before dipping silver, simultaneously or be applied to afterwards on the carrier, also can after silver compound is reduced, be immersed on the carrier.
For guarantee silver all even abundant loads, carrier, preferential oxidation alumina supporter (such as Alpha-alumina), the dipping before, preferably vacuumize in advance, this vacuum tightness preferably is lower than 10mmHg.When flooding with steeping fluid, dipping time is generally 10-60 minute.After the leaching, will be through the carrier drying of dipping.Then, with the activation more than 30 seconds in 100-700 ℃, preferred 160-500 ℃ fluidizing air or the air-flows such as rare gas element such as nitrogen, argon gas of gained carrier, for example 30 seconds-120 minutes, preferred 1-60 minute, activating, thereby make efficient silver catalyst.
The present invention is compared with existing technology and can brings following beneficial effect: in the method for the invention, for fresh or stop after again the drive highly selective silver catalyst that uses, can and need not improve under the condition of initial reaction temperature in the work-ing life that does not reduce the highly selective silver catalyst, improve fast the selectivity at highly selective silver catalyst initial stage; Temperature of reaction when the present invention also can reduce the highly selective of highly selective silver catalyst and occurs, i.e. the adding of ethane so that the activity of silver catalyst improve; The needed time appears in the highly selective that the present invention can also reduce the highly selective silver catalyst, makes its for a long time catalyzed reaction under the highly selective state, improves the average selectivity of highly selective silver catalyst.In addition, in the method for the invention, for the highly selective silver catalyst that is just using in the oxidation of ethylene device, prepare in the oxyethane process toward oxidation of ethylene and to add certain density ethane and improve promotor as catalyst selectivity, the selectivity of oxyethane significantly improves in a short time; And the degree that catalyst activity reduces when selectivity significantly improves is acceptable.The present invention can make its for a long time catalyzed reaction under the highly selective state, thereby its average selectivity to oxyethane is significantly improved after the selectivity that significantly improves the highly selective silver catalyst.
Embodiment
The mensuration of catalyst performance: various silver catalysts of the present invention are tested its activity and selectivity with laboratory microreactor evaluating apparatus.The reactor that uses in the microreactor evaluating apparatus is the stainless steel reaction pipe of internal diameter 4mm, and reaction tubes places heating jacket.The admission space of catalyzer is 1ml, and inert filler is arranged at the bottom, makes beds be positioned at the flat-temperature zone of heating jacket.The condition determination such as the table 1 that adopt in the embodiment of the invention:
Table 1
Annotate: for the concentration of inhibitor ethylene dichloride, 0-2.0ppm is applicable to Comparative Examples 1 and embodiment 2～8, and 0.1-2.0ppm is applicable to embodiment 9～14.
When stable reach above-mentioned reaction conditions after METHOD FOR CONTINUOUS DETERMINATION reactor inlet and exit gas form.Measurement result carries out calculating as follows after volumetric shrinkage is proofreaied and correct selectivity:
Selectivity
Wherein Δ EO is that ethylene oxide concentration is poor in reactor outlet gas and the inlet gas, Δ CO
2Be that gas concentration lwevel is poor in reactor outlet gas and the inlet gas, get the test-results of the mean number of 10 groups of above testing datas as the same day.
The present invention is described further below in conjunction with embodiment, but scope of the present invention is not limited to these embodiment.
Reference example 1
The preparation of highly selective silver catalyst carrier: with 50-200 purpose three water α-Al
2O
3The false water Al of 450g and 200-500 purpose
2O
3100g puts into blender and mixes.Then change in the kneader, the mass ratio that adds nitric acid and water is 100 milliliters in rare nitric acid of 1: 3, but is kneaded into the paste of extrusion moulding.Extrusion moulding is the five hole column form objects of external diameter 8.0mm, long 6.0mm, internal diameter 1.0mm, and drying is 3 hours under 60-120 ℃, and free water content is reduced to below 10 % by weight, obtains green compact.Then green compact are put into electric furnace, be elevated to 1410-1450 ℃ through 30 hours from room temperature, constant temperature 2 hours obtains white α-Al
2O
3Support samples.
The preparation of highly selective silver catalyst: add the 400g quadrol in the glass flask that band stirs, 100g thanomin and 450g deionized water obtain mixed solution.Under stirring silver oxalate is added in the gained mixed solution, temperature remains on about 40 ℃, and silver oxalate is all dissolved.Then to wherein adding ammonium perrhenate 0.4g and cesium sulfate 0.35g, add deionized water again and make the solution total mass reach 2200g, gained solution mixes, and obtains steeping fluid, and is stand-by.In this steeping fluid, in silver atoms, the content of Silver Nitrate is 29 % by weight.Get the white α-Al of the above-mentioned preparation of 100g
2O
3Support samples is put into the container that can vacuumize.Be evacuated to low vacuum in 10mmHg, put into above steeping fluid, the submergence carrier kept 30 minutes.Unnecessary solution is removed in leaching.Carrier behind the dipping heated 8 minutes in 300 ℃ airflow, and ethylene oxide silver catalyst is namely made in cooling.This catalyzer is efficient silver catalyst, contains the silver of 20 % by weight, the caesium of the rhenium of 900 ppm by weight and 1500 ppm by weight.
Use the microreactor evaluating apparatus under the described processing condition of table 1, to measure the activity and selectivity of catalyzer to the highly selective silver catalyst of making.The initial stage selectivity of the highly selective silver catalyst for preparing in this reference example is 83mol%, and highly selective is 89mol%, and latter stage, selectivity was 86mol%; Space-time yield is that EO/ hour * of 220 grams rises catalyzer.
Comparative Examples 1
Adopt the fresh highly selective silver catalyst of preparation in the reference example 1, by ethylene production oxyethane, wherein air speed is 4500/h according to the described processing condition of table 1, and outlet EO concentration is 2.5mol%, and ethane concentration is 0.0mol% always.Its related experiment data see Table 2.
Embodiment 2～8
After device reaches expection load and reaction keep the maximum concentration of ethane to be respectively 0.2mol%, 0.4mol%, 0.6mol%, 0.8mol%, 1.0mol%, 1.5mol% and 2.0mol% before reaching the expection selectivity, all the other are with Comparative Examples 1.
Table 2
As can be seen from Table 2, prepare in the oxyethane process at oxidation of ethylene and to use certain density ethane as promotor, especially preferred is that the ethane maximum concentration is 0.2～1.0mol% before reaction reaches the expection selectivity, so that the temperature of reaction when highly selective occurring significantly reduces, i.e. the adding of ethane so that the activity of silver catalyst improve; In addition, silver catalyst also improves to the highly selective of product; The most important thing is, add a certain amount of ethane so that silver catalyst significantly shortened the time that the selectivity of product reaches maximum, among the present invention can be in 1 month by shortening to more than a year of prior art; That is to say that adding a certain amount of ethane can improve the initial stage selectivity that the oxidation of ethylene epoxy ethane is used the highly selective silver catalyst fast, thereby the highly selective silver catalyst is moved under than the highly selective level.
In addition, as can be seen from Table 2, the height of ethane concentration determines the time that the highly selective of highly selective silver catalyst occurs.The highly selective time of occurrence of the higher then highly selective of ethane concentration silver catalyst more early, the highly selective time of occurrence of the lower then highly selective of ethane concentration silver catalyst is more late.
Need fast temperature is brought up to 240 ℃ or above ability in the prior art so that selectivity reaches 88%, for example realize optionally improving by adding a large amount of inhibitor; The present invention can't be so that catalyst activity reduces in the optionally while of improving fast the highly selective silver catalyst, and the activity of phase anticatalyzer also promotes to some extent.
Embodiment 9
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is initially 0, when accumulative total EO output reaches 600 tons of/cubic metre catalyzer (this moment catalyzer approximately 3～6 months corresponding runtime), temperature of reaction is 228.7 ℃, selectivity 84.6%.At this moment, add ethane in unstripped gas, ethane concentration is controlled at 0.4mol%; Simultaneously, according to the exothermic heat of reaction situation temperature of reaction is reduced 6-15 ℃, adding ethane approximately after 10 hours, suitably adjust temperature of reaction according to reaction condition.Detect temperature of reaction after 10 days and catalyzer to the selectivity of product.After selectivity reaches desired value, in 0.2-2ppmv, suitably improve inhibitor concentration, suitably reduce simultaneously the catalyst activity and selectivity that ethane concentration can keep this moment for a long time.The related experiment data see Table 3.
In the present embodiment, in case because add ethane then the reaction process heat release is obvious, thereby the temperature of reaction appropriateness need to be reduced; Generally ethane begins temperature fall time and continue some hours from adding, and this moment, catalyst activity increased; Probably descend 1 day rear catalyst is active, activity drops to the activity value that adds before the ethane after 3～4 days; The rear catalyst activity was lower in 7～10 days, this moment show as need to be higher the catalyzed reaction temperature.Therefore all detect among the embodiment 9～14 and add the catalyst activity and selectivity of ethane after 7～10 days.
Embodiment 10
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is initially 0, when accumulative total EO output reached 600 tons of/cubic metre catalyzer, temperature of reaction was 228.9 ℃, selectivity 84.7%.At this moment, add ethane in unstripped gas, ethane concentration is controlled at 0.6mol%; Detect temperature of reaction after 10 days and catalyzer to the selectivity of product.The related experiment data see Table 3.
Embodiment 11
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative total EO output reached 600 tons of/cubic metre catalyzer, temperature of reaction was 228.5 ℃, selectivity 84.5%.At this moment, add ethane in unstripped gas, ethane concentration is controlled at 0.8mol%; Detect temperature of reaction after 10 days and catalyzer to the selectivity of product.The related experiment data see Table 3.
Table 3
As can be seen from Table 3, turn round for some time at catalyzer after (aforesaid 3～6 months), prepare in the oxyethane process toward oxidation of ethylene and to add certain density ethane and improve promotor as catalyst selectivity, the used highly selective silver catalyst of ethylene epoxidizing significantly improves in a short time to the selectivity of product, and adds catalyst activity that this concentration ethane sacrifices also in tolerance interval.For example when raw material ethene price was higher, method of the present invention was for just seeming particularly significant the highly selective silver catalyst of running for some time in the ethylene epoxidizing device.
Embodiment 12
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative total EO output reaches 900 tons of/cubic metre catalyzer (this moment, catalyzer reached 5～8 months corresponding runtime), temperature of reaction is 233.2 ℃, selectivity 85.5%.Add ethane this moment in unstripped gas, ethane concentration is controlled at 0.4mol%; Detect temperature of reaction after 7 days and catalyzer to the selectivity of product.The related experiment data see Table 4.
Embodiment 13
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative total EO output reached 900 tons of/cubic metre catalyzer, temperature of reaction was 233.6 ℃, selectivity 85.6%.Add ethane this moment in unstripped gas, ethane concentration is controlled at 0.6mol%; Detect temperature of reaction after 7 days and catalyzer to the selectivity of product.The related experiment data see Table 4.
Embodiment 14
Adopt the highly selective silver catalyst of preparation in the reference example 1, according to the described processing condition of table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, and ethane concentration is 0, when accumulative total EO output reaches 900 tons of/cubic metre catalyzer, temperature of reaction is 233.4 ℃, selectivity 85.4%, add ethane this moment in unstripped gas, and ethane concentration is controlled at 0.8mol%; Detect temperature of reaction after 7 days and catalyzer to the selectivity of product.The related experiment data see Table 4.
Table 4
As can be seen from Table 4, turn round for some time at catalyzer after (aforesaid 5～8 months), prepare in the oxyethane process toward oxidation of ethylene and to add certain density ethane and improve promotor as catalyst selectivity, the used highly selective silver catalyst of ethylene epoxidizing significantly improves in a short time to the selectivity of product, and adds catalyst activity that this concentration ethane sacrifices also in tolerance interval.For example when raw material ethene price was higher, method of the present invention was for just seeming particularly significant the highly selective silver catalyst of running for some time in the ethylene epoxidizing device.
In addition, need fast temperature is brought up to 240 ℃ or above ability in the prior art so that selectivity reaches 88%, for example realize optionally improving by adding a large amount of inhibitor; The present invention is acceptable in the optionally degree of simultaneously catalyst activity reduction that significantly and fast improves the highly selective silver catalyst.
Consider from the overall situation of the factors such as the price of raw material ethene, catalyst life and device running period, the inventive method provides the selection of a good working method for again the user of highly selective silver catalyst.
Claims (20)
1. the method for a highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, it is characterized in that: wherein the highly selective silver catalyst be fresh or stop after again the drive highly selective silver catalyst that uses, ethylene concentration is 20-40mol% in ethylene oxidation reactions gas, oxygen concentration is 6-8.5mol%, gas concentration lwevel is＜2mol%, the concentration of inhibitor is regulated in 0.2-2ppmv, and the concentration of ethane increases afterwards first in 0-2.0mol% and subtracts, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-250 ℃.
2. method according to claim 1, it is characterized in that: after in reaction unit, pack into described highly selective silver catalyst and the running of driving, at first add ethane in the reaction gas and its concentration is controlled at a low concentration in the 0-2.0mol%, then be increased to a higher concentration and keep this ethane concentration until reaction reaches expection ethane concentration is reduced during selectivity again, and in the scope of 0.2-2ppmv appropriate rising inhibitor concentration.
3. method according to claim 2, it is characterized in that: at first add ethane in the reaction gas and its concentration be controlled at 0-1.0mol%, then when device reaches the expection load, raise ethane concentration for 0.2-2.0mol% and when keeping this concentration to reaction to reach the expection selectivity again with reaction gas in ethane concentration be reduced to 0-0.8mol%.
4. method according to claim 3, it is characterized in that: at first add ethane in the reaction gas and its concentration be controlled at 0-0.8mol%, then when device reaches the expection load, raise ethane concentration for 0.4-1.2mol% and when keeping this concentration to reaction to reach the expection selectivity again with reaction gas in ethane concentration be reduced to 0.2-0.6mol%.
5. the described method of any one according to claim 1～4, it is characterized in that: it is 2～20 days that described device reaches when load expection apart from the runtime of driving, described expection selectivity is 87～93mol%, described reaction reach expection during selectivity apart from the runtime of driving be 20 days～6 months.
6. method according to claim 5, it is characterized in that: it is 7～10 days that described device reaches when load expection apart from the runtime of driving, described expection selectivity is 88～91mol%, described reaction reach expection during selectivity apart from the runtime of driving be 1～2 month.
7. the described method of any one according to claim 1～4 is characterized in that: use nitrogen oxygen concentration when causing steady gas to be 6-7mol%, use methane oxygen concentration when causing steady gas to be 7.5-8.5mol%.
8. the described method of any one according to claim 1～4 is characterized in that: described highly selective silver catalyst is that the initial stage selectivity is greater than 82mol%; Highly selective is preferably greater than 87mol% greater than 86mol%; Latter stage, selectivity was greater than 82mol%, was preferably greater than 84mol%; And space-time yield is the catalyzer of EO/ hour * liter of 160-280 gram.
9. the described method of any one according to claim 1～4 is characterized in that: described inhibitor is monochlorethane and/or ethylene dichloride.
10. the described method of any one according to claim 1～4 is characterized in that: described oxidizing reaction temperature is 190-240 ℃, preferred 200-230 ℃.
11. the method for a highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, it is characterized in that: wherein the highly selective silver catalyst is for running well in the oxidation of ethylene device but selectivity does not reach the catalyzer of desired value, ethylene concentration is 20-40mol% in ethylene oxidation reactions gas, oxygen concentration is 6-8.5mol%, gas concentration lwevel is＜2mol%, the concentration of inhibitor is regulated in 0.2-2ppmv, adding ethane in the reaction gas, to make its concentration be 0.1-1.5mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-260 ℃; When in reaction gas, adding ethane, before or after will install 5-20 ℃ of interior reaction temperature reduction; When reaching the anticipation reaction selectivity, in 0.2-2ppmv, suitably improve inhibitor concentration, in the 0.1-1.5mol% scope, suitably reduce simultaneously ethane concentration.
12. method according to claim 11 is characterized in that: described anticipation reaction selectivity is 87～93mol%, and described is 3～20 days apart from adding the ethane time when reaching the anticipation reaction selectivity.
13. method according to claim 12 is characterized in that: described anticipation reaction selectivity is 88～91mol%, and described is 7～10 days apart from adding the ethane time when reaching the anticipation reaction selectivity.
14. method according to claim 11 is characterized in that: when in reaction gas, adding ethane, before or after will install interior reaction temperature and reduce 6-15 ℃, preferably 8-10 ℃.
15. method according to claim 11 is characterized in that: adding ethane in the reaction gas, to make its concentration be 0.2-1.2mol%, reduces ethane concentration to 0.1-0.8mol% when reaching the anticipation reaction selectivity.
16. method according to claim 15 is characterized in that: adding ethane in the reaction gas, to make its concentration be 0.4-0.8mol%, reduces ethane concentration to 0.2-0.4mol% when reaching the anticipation reaction selectivity.
17. the described method of any one according to claim 11～16 is characterized in that: use nitrogen oxygen concentration when causing steady gas to be 6-7mol%, use methane oxygen concentration when causing steady gas to be 7.5-8.5mol%; And described inhibitor is monochlorethane and/or ethylene dichloride.
18. the described method of any one according to claim 11～16 is characterized in that: described highly selective silver catalyst is that the initial stage selectivity is greater than 82mol%; Highly selective is preferably greater than 87mol% greater than 86mol%; Latter stage, selectivity was greater than 82mol%, was preferably greater than 84mol%; And space-time yield is the catalyzer of EO/ hour * liter of 160-280 gram.
19. the described method of any one according to claim 11～16 is characterized in that: described oxidizing reaction temperature is 190-250 ℃, preferred 200-240 ℃.
20. the described method of any one according to claim 11～16, it is characterized in that: running well in the described oxidation of ethylene device but duration of service that it is described highly selective silver catalyst after the device running at full capacity that selectivity does not reach the catalyzer of desired value has reached 1～12 month, preferred 3～10 months.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1665796A (en) * | 2002-06-28 | 2005-09-07 | 国际壳牌研究有限公司 | A method for the start-up of an epoxidation process, a catalyst and a process for the epoxidation of an olefin |
| CN1784269A (en) * | 2003-05-07 | 2006-06-07 | 国际壳牌研究有限公司 | Silver-containing catalysts, the manufacture method and use thereof |
| WO2009042300A1 (en) * | 2007-09-26 | 2009-04-02 | Sd Lizenzverwertungsgesellschaft Mbh & Co. Kg | Process for initiating a highly selective ethylene oxide catalyst |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1665796A (en) * | 2002-06-28 | 2005-09-07 | 国际壳牌研究有限公司 | A method for the start-up of an epoxidation process, a catalyst and a process for the epoxidation of an olefin |
| CN1784269A (en) * | 2003-05-07 | 2006-06-07 | 国际壳牌研究有限公司 | Silver-containing catalysts, the manufacture method and use thereof |
| WO2009042300A1 (en) * | 2007-09-26 | 2009-04-02 | Sd Lizenzverwertungsgesellschaft Mbh & Co. Kg | Process for initiating a highly selective ethylene oxide catalyst |
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