CN103360346B - 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 the method for a kind 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 highly selective silver catalyst initial stage optionally just using in method and a kind of oxidation of ethylene device significantly promotes.
Background technology
Under silver catalyst effect, direct oxidation of ethylene to mainly generates oxyethane (EO), side reaction occurs simultaneously and generates carbonic acid gas and water etc., and wherein activity, selectivity and stability are the main performance index of silver catalyst.So-called activity refers to the temperature of reaction that process for ethylene oxide production reaches required when necessarily reacting load; Temperature of reaction is lower, and the activity of catalyzer is higher.So-called selectivity refers to that in reaction, ethylene conversion becomes the ratio of the mole number of oxyethane and the total reaction mole number of ethene.So-called stability is then expressed as the fall off rate of activity and selectivity, and the stability of fall off rate more small catalyst is better.Produce at oxidation of ethylene in the process of oxyethane and use high reactivity, highly selective and the silver catalyst that has good stability greatly to increase economic efficiency, the silver catalyst therefore manufacturing high reactivity, highly selective and good stability is a Main way of silver catalyst research.But the performance of silver catalyst, except having important relationship with the composition of catalyzer and preparation method, also has important relationship with the operation of catalyzer.
Direct oxidation of ethylene to epoxy ethane silver catalyst is divided into high reactivity silver catalyst, middle highly selective silver catalyst and highly selective silver catalyst three class.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 280 grams of EO/ hour * and rise catalyzer; The initial stage selectivity of middle highly selective silver catalyst is 81-85mol%, and most highly selective is 85-86mol%, and latter stage, selectivity was 80-82mol%, and space-time yield can reach 200-280 gram of EO/ hour * and rise catalyzer; The initial stage selectivity of highly selective silver catalyst is 82-85mol%, and most highly selective is 87-92mol%, and latter stage, selectivity was 82-84mol%, and space-time yield can reach 160-220 gram of EO/ hour * 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 uses high-selective ethylene epoxidation reaction silver catalyst, and it obviously reduces relative to the ethene material consumption of traditional high activity epoxidation catalyst.But for a given ethylene oxide yield, high-selectivity catalyst needs to use the temperature of reaction higher than high activated catalyst, and its catalyst activity changing down is also very fast.Therefore, in order to take into account the activity of catalyzer, selectivity and stability, in these years Ge great silver catalyst research company not only carries out unremitting effort on carrier and preparation thereof, also improves oxirane production technology and equipment, to give full play to the usefulness of silver catalyst.
Highly selective silver catalyst is in the starting stage for epoxidation process, and catalyzer need experience one so-called " break-through phase "; In this stage (be generally and drive latter more than 1 year), selectivity of catalyst is very low, even if use reaction control agent to be also like this, need in a commercial start-up to adjust for a long time reaction just can be made can to run under the comparatively highly selective level of catalyzer.For this reason, 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 stage optionally Technologies.Patent EP1517751A2 and Chinese patent application 03815308.4 disclose one can improve high-selectivity catalyst initial stage optionally starting method: at catalyst temperature higher than at 250 DEG C, make loading type highly selective epoxidation catalyst containing 0.19g silver at the most on every square metre of carrier surface with containing oxygen contact raw, 150 hours at the most time length, reduce catalyst temperature subsequently to the highest 250 DEG C, and make catalyzer and the contact raw containing alkene and oxygen, significantly can improve the initial stage selectivity of highly selective silver catalyst.US20070670325 and CN101410178A proposes first to carry out pyroprocessing before catalyzer passes into reaction raw materials gas mixture, passes into feed oxygen at least 5 minutes at 350 DEG C.This patent application is claimed, catalyzer, after oxygen pyroprocessing, significantly increases the initial selectivity of catalyzer; And show catalytic mechanical intensity enhancing, improve catalytic performance.Chinese patent application 200680012785 provides a kind of method of producing oxyethane: under the existence 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 proposes to make catalyzer stand Organohalogen compounds pre-soak period in the driving scheme of oxyethane: at the temperature lower than reactor service temperature, under the existence of Organohalogen compounds, conventional catalyzer is made to stand a pre-soak period.The method of this process catalyzer can reduce the generation of carbonic acid gas.With Organohalogen compounds pre-soakings highly selective silver catalyst in CN03815312, and with not containing organic halid unstripped gas or the feed gas containing lower concentration Organohalogen compounds.The method makes production oxyethane have highly selective.In US20090082584 and US7553980, propose the process relating to and start highly selective silver catalyst: the startup of highly selective silver catalyst controls the activity of silver catalyst by passing into high concentration carbon dioxide.In other words, the method for this invention is when the conversion requirements controlling ethene in reactor improves temperature of reaction, realizes by improving gas concentration lwevel in charging.
These novel methods above-mentioned not only from adjustment reaction gas composition, and are started with from silver catalyst initial stage driving technique and are improved the initial performance of oxyethane highly selective silver catalyst.But the improvement that the activity and selectivity of these methods to highly selective silver catalyst brings is also very limited, therefore, this area still needs to be improved by the technique of oxidation of ethylene epoxy ethane employing highly selective silver catalyst, is beneficial to the initial reaction performance improving efficient silver catalyst.
In addition, for the highly selective silver catalyst just used in oxidation of ethylene device, improve in prior art its optionally method be generally by adding a large amount of inhibitor to realize, as selectivity just made to be increased to 88% by adding a large amount of pentane and temperature of reaction being brought up to fast 240 DEG C or more.
In recent years, bibliographical information some improve highly selective silver catalysts optionally Technologies.As Chinese patent application 200680012785 provides a kind of method of producing oxyethane: under the existence of water and halogen contained compound, make ethene contact with silver catalyst with oxygen, catalyst performance be improved significantly.US4874879 and US5155242 proposes to make catalyzer stand Organohalogen compounds pre-soak period in the driving scheme of oxyethane: at the temperature lower than reactor service temperature, under the existence of Organohalogen compounds, conventional catalyzer is made to stand a pre-soak period.The method of this process catalyzer can reduce the generation of carbonic acid gas.With Organohalogen compounds pre-soakings highly selective silver catalyst in CN03815312, and with not containing organic halid unstripped gas or the feed gas containing lower concentration Organohalogen compounds.The method makes production oxyethane have highly selective.
The improvement that the selectivity of these methods above-mentioned to highly selective silver catalyst is brought is also very limited, therefore, this area still needs to be improved by the technique of oxidation of ethylene epoxy ethane employing highly selective silver catalyst, is beneficial to the selectivity improving highly selective silver catalyst fast.
Summary of the invention
The invention provides the method for a kind of highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, wherein highly selective silver catalyst is highly selective silver catalyst that is fresh or that again drive use after stopping, in ethylene oxidation reactions gas, ethylene concentration is 20-40mol%, oxygen concentration is 6-8.5mol%, gas concentration lwevel is < 2mol%, the concentration of inhibitor regulates in 0.2-2ppmv, the concentration of ethane first increases and subtracts afterwards in 0-2.0mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-250 DEG C.
With in a concrete embodiment, in reaction unit, load described highly selective silver catalyst and drive running after, first in reaction gas, progressively add ethane and its concentration is controlled the low concentration in 0-2.0mol%, then be increased to a higher concentration and keep this ethane concentration until reaction reach expection selectivity time again by ethane concentration reduce, and in the scope of 0.2-2ppmv appropriate increase inhibitor concentration.Wherein, preferred scheme is, first in reaction gas, progressively adds ethane and controls at 0-1.0mol% by its concentration, more preferably 0-0.8mol%; Again ethane concentration in reaction gas is reduced to 0-0.8mol%, more preferably 0.2-0.6mol% when then raising ethane concentration for 0.2-2.0mol%, more preferably 0.4-1.2mol% when device reaches expection load and keep this concentration to reaction to reach expection selectivity.
In such scheme, described device reach expection load time apart from drive runtime be 2 ~ 20 days, preferably 7 ~ 10 days, described expection selectivity is 87 ~ 93mol%, preferably 88 ~ 91mol%, when described reaction reaches expection selectivity apart from runtime of driving be 20 days ~ 6 months, preferably 1 ~ 2 month.React reach expection selectivity time while reduction ethane concentration in the scope of 0.2-2ppm appropriate increase inhibitor concentration, so far, for the initial stage promoting highly selective silver catalyst optionally scheme complete enforcement.
In the above-described embodiment, when using nitrogen for causing steady gas, oxygen concentration is 6-7mol%, and when using methane for causing steady gas, oxygen concentration is 7.5-8.5mol%.Described oxidizing reaction temperature is for being preferably 190-240 DEG C, more preferably 200-230 DEG C.
The present invention also provides a kind of highly selective silver catalyst catalyzed ethylene to be oxidized the method for epoxy ethane, wherein highly selective silver catalyst is to run well in device but selectivity does not reach the catalyzer of desired value, in ethylene oxidation reactions gas, ethylene concentration is 20-40mol%, oxygen concentration is 6-8.5mol%, gas concentration lwevel is < 2mol%, the concentration of inhibitor regulates in 0.2-2ppmv, in reaction gas, add ethane makes its concentration be 0.1-1.5mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-260 DEG C; While add ethane in reaction gas, before or after by device interior reaction temperature reduce 5-20 DEG C; When reaching anticipation reaction selectivity, in 0.2-2ppmv, suitably improving inhibitor concentration, within the scope of 0.1-1.5mol%, suitably reducing ethane concentration simultaneously.
In a preferred embodiment, described anticipation reaction selectivity is 87 ~ 93mol%, described in be 3 ~ 20 days apart from adding the ethane time when reaching anticipation reaction selectivity.More preferably described anticipation reaction selectivity is 88 ~ 91mol%, described in be 7 ~ 10 days apart from adding the ethane time when reaching anticipation reaction selectivity.
In the present invention, preferably while add ethane in reaction gas, before or after by device interior reaction temperature reduce 6-15 DEG C, more preferably reduce 8-10 DEG C.
In the present invention, in reaction gas, preferably adding ethane make its concentration be 0.2-1.2mol%, reducing ethane concentration when reaching anticipation reaction selectivity to 0.1-0.8mol%.More preferably in reaction gas, add ethane makes its concentration be 0.4-0.8mol%, reduces ethane concentration to 0.2-0.4mol% when reaching anticipation reaction selectivity.
In the present invention, when using nitrogen for causing steady gas, oxygen concentration is 6-7mol%, and when using methane for causing steady gas, oxygen concentration is 7.5-8.5mol%; And described inhibitor is monochlorethane and/or ethylene dichloride.In addition, described in preferred the present invention, oxidizing reaction temperature is 190-250 DEG C, is more preferably 200-240 DEG C.In the present invention, running well in preferred described oxidation of ethylene device but after device running at full capacity, reaching 1 ~ 12 month, more preferably 3 ~ 10 months the duration of service that the catalyzer that selectivity does not reach desired value is described highly selective silver catalyst.
In above-mentioned two schemes of the present invention, described highly selective silver catalyst is that initial stage selectivity is greater than 82mol%; Most highly selective is greater than 86mol%, is preferably greater than 87mol%; Latter stage, selectivity was greater than 82mol%, was preferably greater than 84mol%; And space-time yield is the catalyzer that 160-280 gram of EO/ hour * rises.Wherein said initial stage selectivity refers to that silver catalyst is brought into use to the average selectivity in rear at full capacity 1 month that reaches device technique requirement, and described latter stage, selectivity referred to the average selectivity of last 2 ~ 3 months that silver catalyst uses; The work-ing life of whole highly selective silver catalyst is generally 2 ~ 3 years.
By the reaction gas of oxidation of ethylene epoxy ethane, it usually comprises ethene, oxygen, causes steady gas and inhibitor.As causing steady gas, its objective is to keep the concentration of ethene and oxygen in reaction gas to operate in limits of explosion, and cause steady gas and itself do not participate in reaction, negatively influencing is not had to reaction.Cause steady gas and be generally nitrogen, methane or its mixture: methane is conducive to improving oxygen content and the molten value of air heat in unstripped gas, favourable to reaction; But some producer limits due to processing condition, use nitrogen as causing steady gas.The object adding inhibitor in reaction gas is to suppress the activity of silver catalyst and improving selectivity; For highly selective silver catalyst, inhibitor has the effect improving 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 reaction gas, the increase of carbonic acid gas can affect the stability of efficient silver catalyst.In addition, in factory's use procedure, in initial action gas, usually also some foreign gases can be there are, as hydrogen, ethane, argon gas.Argon gas is rare gas element, does not participate in reaction.In prior art, it is generally acknowledged that ethane content rising can cause high reactivity silver catalyst activity to raise and selectivity declines to a great extent, reaction very exothermic can be made and selectivity aggravation decline when ethane content reaches certain value (as being greater than 0.7%).Therefore, generally do not allow the impurity ethane of high density to occur in ethylene epoxidizing process in prior art, generally the concentration of ethane in reaction gas to be controlled within 0.5mol% and its concentration does not change during whole catalyst life.But, in the present invention, for the fresh or highly selective silver catalyst that uses of again driving after stopping, even adding the initial stage (as before reaching device load) of ethane, while the activity preparing oxyethane at oxidation of ethylene significantly promotes, its selectivity of product also there will not be obvious decline.Ethane, as highly selective silver catalyst initial stage optionally promotor, can bring obviously beneficial effect.In addition, in the present invention, for the highly selective silver catalyst just used in oxidation of ethylene device, by first adding certain density ethane, reducing ethane concentration again after reaching expection selectivity, the selectivity of highly selective silver catalyst to oxyethane is largely increased fast, and the decreasing value of catalyst activity is also in acceptable scope.
In one embodiment of the invention, the following component that described highly selective silver catalyst comprises carrier and it deposits, silver-colored activeconstituents; Rhenium auxiliary agent; Optionally, the coassist agent of rhenium auxiliary agent; Optionally, alkali metal promoter; Optionally, 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 counts 1-30 % by weight with silver element, is preferably 10-29 % by weight; And/or rhenium content counts 5ppm-2500ppm with rhenium element, be preferably 10ppm-1500ppm; If and/or the coassist agent of rhenium auxiliary agent exists, its amount counts 5ppm-1000ppm with this coassist agent element, be preferably 10ppm-500ppm; If and/or alkali metal promoter exists, its amount counts 5ppm-2000ppm with alkali metal, be preferably 10ppm-1500ppm; If and/or base earth metal promoter exists, its amount counts 5ppm-2000ppm with alkali earth metal, be preferably 10ppm-1200ppm.
As the silver of activeconstituents, it both can exist with argent, also can exist with silver compound.As silver compound, silver suboxide, Silver Nitrate and/or silver oxalate can be mentioned.As rhenium auxiliary agent, it both can exist with rhenium metal, also can exist with rhenium compound.As rhenium compound, the oxide compound of rhenium, perrhenic acid, perrhenate can be mentioned, 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 the compound being selected from one or more elements in lower group or this element: chromium, molybdenum, tungsten, boron, cerium, sulphur and manganese.As alkali metal promoter, it can be the compound being selected from one or more metals in lithium, sodium, potassium, rubidium and caesium or this metal, is preferably lithium, potassium or caesium or its compound.As base earth metal promoter, it can be the compound being selected from one or more metals in magnesium, calcium, strontium and barium or this metal, is preferably barium or strontium or its compound.
As mentioned above, highly selective silver catalyst of the present invention is advantageously loaded catalyst.As the carrier being suitable for this catalyzer, it can be any carrier being suitable for silver catalyst, various oxide carrier or composite oxide carrier can be mentioned to this, such as silicon oxide, aluminum oxide (as Alpha-alumina), alumina-silica silicon 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.Such as, the method preparation of highly selective silver catalyst used in the present invention by comprising the following steps: the first step, uses the solution impregnating carrier of silver compound, organic amine, rhenium auxiliary agent, the coassist agent of optional rhenium auxiliary agent, optional alkali metal promoter and the optional base earth metal promoter containing q.s; Second step, elimination steeping fluid; And the 3rd step, in air or rare gas element, second step gained carrier is activated, make efficient silver catalyst.
Above-mentioned silver compound can for being suitable for by any silver compound of ethylene making oxyethane silver catalyst.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 final silver catalyst prepared, and preferred 10-29 % by weight, based on total catalyst weight in silver atoms.
Above-mentioned organic amine compound can for being suitable for any organic amine compound preparing 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, pyridine, butylamine, quadrol, 1,3-propylene diamine, thanomin or its mixture is preferably used, the mixture of such as quadrol and thanomin.
In dipping solution except silver compound, organic amine, rhenium auxiliary agent, optional alkali metal promoter and optional base earth metal promoter, the coassist agent of rhenium auxiliary agent can also be added, to improve the activity of gained silver catalyst, selectivity and stability further.The coassist agent of rhenium auxiliary agent can be the compound of arbitrary transition metal in the periodic table of elements (such as chromium, molybdenum, tungsten, boron, cerium and manganese), or the mixture of several transistion metal compound, the oxygen acid of preferred group vib and VIIB race element and salt thereof, such as 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 make the coassist agent of rhenium auxiliary agent in final catalyzer with the weight content of this coassist agent elemental metal for 5ppm-1000ppm, is preferably 10ppm-500ppm, based on the gross weight of efficient silver catalyst.The coassist agent of rhenium auxiliary agent can before dipping silver, also can be immersed on carrier after silver compound is reduced simultaneously or be applied to afterwards on carrier.
For ensureing all even abundant load of silver, carrier, preferential oxidation alumina supporter (as Alpha-alumina), before impregnation, preferably vacuumizes in advance, and this vacuum tightness is preferably lower than 10mmHg.When using impregnation fluid, dipping time is generally 10-60 minute.After leaching, by the carrier drying through dipping.Then, by the activation more than 30 seconds in the fluidizing air of 100-700 DEG C, preferably 160-500 DEG C or rare gas element are as the air-flow such as nitrogen, argon gas of gained carrier, such as 30 seconds-120 minutes, preferred 1-60 minute, to activate, thus made efficient silver catalyst.
Compared to the prior art the present invention can bring following beneficial effect: in the method for the invention, for the fresh or highly selective silver catalyst that uses of again driving after stopping, under the work-ing life not reducing highly selective silver catalyst and the condition not needing raising initial reaction temperature, the selectivity at highly selective silver catalyst initial stage can be improved fast; The present invention also can reduce temperature of reaction when the most highly selective of highly selective silver catalyst occurs, namely adding of ethane the activity of silver catalyst is improved; Time required for the most highly selective that the present invention can also reduce highly selective silver catalyst occurs, make its catalyzed reaction under highly selective state for a long time, improve the average selectivity of highly selective silver catalyst.In addition, in the method for the invention, for the highly selective silver catalyst just used in oxidation of ethylene device, prepare in oxyethane process toward oxidation of ethylene and 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 while selectivity significantly improves is acceptable.The present invention, after the selectivity significantly improving highly selective silver catalyst, can make its catalyzed reaction under highly selective state for a long time, thus make it significantly improve the average selectivity of oxyethane.
Embodiment
The mensuration of catalyst performance: various silver catalyst laboratories of the present invention microreactor evaluating apparatus tests its activity and selectivity.The reactor used in microreactor evaluating apparatus is the stainless steel reaction pipe of internal diameter 4mm, and reaction tubes is placed in heating jacket.The admission space of catalyzer is 1ml, and inert filler is arranged at bottom, makes beds be positioned at the flat-temperature zone of heating jacket.The condition determination adopted in the embodiment of the present invention is as table 1:
Table 1
Note: for the concentration of inhibitor ethylene dichloride, 0-2.0ppm is applicable to comparative example 1 and embodiment 2 ~ 8,0.1-2.0ppm is applicable to embodiment 9 ~ 14.
METHOD FOR CONTINUOUS DETERMINATION reactor inlet and exit gas composition after above-mentioned reaction conditions is reached when stable.Measurement result calculates selectivity after carrying out volumetric shrinkage correction as follows:
Selectivity
Wherein Δ EO is reactor outlet gas and inlet gas ethylene oxide concentration difference, Δ CO
2be that in reactor outlet gas and inlet gas, gas concentration lwevel is poor, get the test-results of mean number as the same day of more than 10 groups testing datas.
The present invention is described further below in conjunction with embodiment, but scope of the present invention is not limited to these embodiments.
Reference example 1
The preparation of highly selective silver catalyst carrier: by 50-200 object three water α-Al
2o
3the false water Al of 450g and 200-500 object
2o
3100g puts into blender and mixes.Then proceed in kneader, the mass ratio adding nitric acid and water is the dust technology 100 milliliters of 1: 3, and being kneaded into can 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 at 60-120 DEG C, drying 3 hours, makes free water content be reduced to less than 10 % by weight, obtain green compact.Then green compact are put into electric furnace, be elevated to 1410-1450 DEG C through 30 hours from room temperature, constant temperature 2 hours, obtain white α-Al
2o
3support samples.
The preparation of highly selective silver catalyst: add 400g quadrol in the glass flask that band stirs, 100g thanomin and 450g deionized water, obtain mixed solution.Added by silver oxalate in gained mixed solution under stirring, temperature remains on about 40 DEG C, and silver oxalate is all dissolved.Then add ammonium perrhenate 0.4g and cesium sulfate 0.35g wherein, then add deionized water and make solution total mass reach 2200g, gained solution mixes, and obtains steeping fluid, 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 puts into the container that can vacuumize.Be evacuated to low vacuum in 10mmHg, put into above steeping fluid, submergence carrier, keep 30 minutes.Leaching removes unnecessary solution.Carrier after dipping heats 8 minutes in the airflow of 300 DEG C, and cooling, namely makes ethylene oxide silver catalyst.This catalyzer is efficient silver catalyst, containing the silver of 20 % by weight, and the rhenium of 900 weight ppm and the caesium of 1500 weight ppm.
The activity and selectivity of catalyzer is measured under microreactor evaluating apparatus processing condition described in table 1 are used to the highly selective silver catalyst made.The initial stage selectivity of the highly selective silver catalyst prepared in this reference example is 83mol%, and most highly selective is 89mol%, and latter stage, selectivity was 86mol%; Space-time yield is that 220 grams of EO/ hour * rise catalyzer.
Comparative example 1
Adopt the fresh highly selective silver catalyst of preparation in reference example 1, according to processing condition described in table 1 by ethylene production oxyethane, wherein air speed is 4500/h, and outlet EO concentration is 2.5mol%, and ethane concentration is 0.0mol% always.Its relevant experimental data is in table 2.
Embodiment 2 ~ 8
Device reach expection load after and reaction reach expection selectivity before keep the maximum concentration of ethane to be respectively 0.2mol%, 0.4mol%, 0.6mol%, 0.8mol%, 1.0mol%, 1.5mol% and 2.0mol%, all the other are with comparative example 1.
Table 2
As can be seen from Table 2, preparing in oxyethane process at oxidation of ethylene uses certain density ethane as promotor, especially preferred is that ethane maximum concentration is 0.2 ~ 1.0mol% before reaction reaches expection selectivity, temperature of reaction when there is most highly selective is significantly reduced, namely adding of ethane the activity of silver catalyst is improved; In addition, the most highly selective of silver catalyst to product also improves; The most important thing is, adding the time that a certain amount of ethane makes the selectivity of silver catalyst to product reach maximum significantly shortens, and can be within 1 month by shortening to more than a year of prior art in the present invention; That is add the initial stage selectivity that a certain amount of ethane can improve oxidation of ethylene epoxy ethane highly selective silver catalyst fast, thus highly selective silver catalyst is run under comparatively highly selective level.
In addition, as can be seen from Table 2, the height of ethane concentration determines the time that the most highly selective of highly selective silver catalyst occurs.More early, the most highly selective time of occurrence of ethane concentration lower then highly selective silver catalyst is more late for the most highly selective time of occurrence of ethane concentration higher then highly selective silver catalyst.
Selectivity just can be made to reach 88% compared to needing temperature to be brought up to fast 240 DEG C or more in prior art, such as, optionally improve by adding a large amount of inhibitor to realize; The present invention optionally can't make catalyst activity reduce quick raising highly selective silver catalyst simultaneously, and the activity of phase anticatalyzer also promotes to some extent.
Embodiment 9
Adopt the highly selective silver catalyst of preparation in reference example 1, according to processing condition described in 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 EO output reaches 600 tons of/cubic metre of catalyzer (now catalyzer about 3 ~ 6 months corresponding runtime), temperature of reaction is 228.7 DEG C, selectivity 84.6%.Now, in unstripped gas, add ethane, ethane concentration controls at 0.4mol%; Meanwhile, according to exothermic heat of reaction situation, temperature of reaction being reduced 6-15 DEG C, adding ethane after about 10 hours, suitably adjusting temperature of reaction according to reaction condition.Detect the 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 reduction ethane concentration can keep catalyst activity and selectivity now for a long time simultaneously.Relevant experimental data is in table 3.
In the present embodiment, because once add ethane, reaction process heat release is obvious, thus needs temperature of reaction appropriateness to reduce; Temperature fall time generally from adding ethane and continue some hours, now catalyst activity increases; General catalyst activity reduction after 1 day, after 3 ~ 4 days, activity decrease is to the activity value before adding ethane; Within 7 ~ 10 days, rear catalyst activity is lower, now shows as the catalyzed reaction temperature that needs are higher.Therefore all detect in 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 reference example 1, according to processing condition described in 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 EO output reaches 600 tons of/cubic metre of catalyzer, temperature of reaction is 228.9 DEG C, selectivity 84.7%.Now, in unstripped gas, add ethane, ethane concentration controls at 0.6mol%; Detect the temperature of reaction after 10 days and catalyzer to the selectivity of product.Relevant experimental data is in table 3.
Embodiment 11
Adopt the highly selective silver catalyst of preparation in reference example 1, according to processing condition described in table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative EO output reaches 600 tons of/cubic metre of catalyzer, temperature of reaction is 228.5 DEG C, selectivity 84.5%.Now, in unstripped gas, add ethane, ethane concentration controls at 0.8mol%; Detect the temperature of reaction after 10 days and catalyzer to the selectivity of product.Relevant experimental data is in table 3.
Table 3
As can be seen from Table 3, after catalyzer operates for some time (3 ~ 6 months as above), prepare in oxyethane process toward oxidation of ethylene and add certain density ethane and improve promotor as catalyst selectivity, the selectivity of ethylene epoxidizing highly selective silver catalyst used to product significantly improves in a short time, and adds catalyst activity that this concentration ethane sacrifices also in tolerance interval.Such as when feed ethylene price is higher, method of the present invention for for some time that operates in ethylene epoxidizing device highly selective silver catalyst just seem particularly significant.
Embodiment 12
Adopt the highly selective silver catalyst of preparation in reference example 1, according to processing condition described in table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative EO output reaches 900 tons of/cubic metre of catalyzer (now catalyzer has reached 5 ~ 8 months corresponding runtime), temperature of reaction is 233.2 DEG C, selectivity 85.5%.Now in unstripped gas, add ethane, ethane concentration controls at 0.4mol%; Detect the temperature of reaction after 7 days and catalyzer to the selectivity of product.Relevant experimental data is in table 4.
Embodiment 13
Adopt the highly selective silver catalyst of preparation in reference example 1, according to processing condition described in table 1 by ethylene production oxyethane, wherein air speed is 4500/h, outlet EO concentration is 2.5mol%, ethane concentration is 0, when accumulative EO output reaches 900 tons of/cubic metre of catalyzer, temperature of reaction is 233.6 DEG C, selectivity 85.6%.Now in unstripped gas, add ethane, ethane concentration controls at 0.6mol%; Detect the temperature of reaction after 7 days and catalyzer to the selectivity of product.Relevant experimental data is in table 4.
Embodiment 14
Adopt the highly selective silver catalyst of preparation in reference example 1, according to processing condition described in 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 EO output reaches 900 tons of/cubic metre of catalyzer, temperature of reaction is 233.4 DEG C, selectivity 85.4%, now adds ethane in unstripped gas, and ethane concentration controls at 0.8mol%; Detect the temperature of reaction after 7 days and catalyzer to the selectivity of product.Relevant experimental data is in table 4.
Table 4
As can be seen from Table 4, after catalyzer operates for some time (5 ~ 8 months as above), prepare in oxyethane process toward oxidation of ethylene and add certain density ethane and improve promotor as catalyst selectivity, the selectivity of ethylene epoxidizing highly selective silver catalyst used to product significantly improves in a short time, and adds catalyst activity that this concentration ethane sacrifices also in tolerance interval.Such as when feed ethylene price is higher, method of the present invention for for some time that operates in ethylene epoxidizing device highly selective silver catalyst just seem particularly significant.
In addition, selectivity just can be made to reach 88% compared to needing temperature to be brought up to fast 240 DEG C or more in prior art, such as, optionally improve by adding a large amount of inhibitor to realize; The present invention is significantly and the degree that optionally catalyst activity reduces improving fast highly selective silver catalyst is acceptable simultaneously.
Consider from the overall situation of the factors such as the price of feed ethylene, catalyst life and device running period, the inventive method provides the selection of a good working method to again the user of highly selective silver catalyst.
Claims (24)
1. the method for a highly selective silver catalyst catalyzed ethylene oxidation epoxy ethane, it is characterized in that: wherein highly selective silver catalyst is highly selective silver catalyst that is fresh or that again drive use after stopping, in ethylene oxidation reactions gas, ethylene concentration is 20-40mol%, oxygen concentration is 6-8.5mol%, gas concentration lwevel is < 2mol%, the concentration of inhibitor regulates in 0.2-2ppmv, the concentration of ethane first increases and subtracts afterwards in 0-2.0mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-250 DEG C;
In reaction unit, load described highly selective silver catalyst and drive running after, first in reaction gas, add ethane and its concentration is controlled at 0-1.0mol%, then device reach expection load time by ethane concentration raise for 0.2-2.0mol% and keep this concentration to reaction reach expection selectivity time again ethane concentration in reaction gas is reduced to 0-0.8mol%, and in the scope of 0.2-2ppmv appropriate increase inhibitor concentration.
2. method according to claim 1, it is characterized in that: first in reaction gas, add ethane and its concentration is controlled at 0-0.8mol%, when then raising ethane concentration for 0.4-1.2mol% when device reaches expection load and keep this concentration to reaction to reach expection selectivity, again ethane concentration in reaction gas is reduced to 0.2-0.6mol%.
3. according to the method described in claim 1 or 2, it is characterized in that: described device reach expection load time apart from drive runtime be 2 ~ 20 days, described expection selectivity is 87 ~ 93mol%, described reaction reach expection selectivity time apart from drive runtime be 20 days ~ 6 months.
4. method according to claim 3, it is characterized in that: described device reach expection load time apart from drive runtime be 7 ~ 10 days, described expection selectivity is 88 ~ 91mol%, described reaction reach expection selectivity time apart from drive runtime be 1 ~ 2 month.
5. according to the method described in claim 1 or 2, it is characterized in that: when using nitrogen for causing steady gas, oxygen concentration is 6-7mol%, when using methane for causing steady gas, oxygen concentration is 7.5-8.5mol%.
6. according to the method described in claim 1 or 2, it is characterized in that: described highly selective silver catalyst is that initial stage selectivity is greater than 82mol%; Most highly selective is greater than 86mol%; Latter stage, selectivity was greater than 82mol%; And space-time yield is the catalyzer that 160-280 gram of EO/ hour * rises.
7. according to the method described in claim 6, it is characterized in that: described highly selective silver catalyst is greater than 87mol% for most highly selective; Latter stage, selectivity was greater than the catalyzer of 84mol%.
8. according to the method described in claim 1 or 2, it is characterized in that: described inhibitor is monochlorethane and/or ethylene dichloride.
9. according to the method described in claim 1 or 2, it is characterized in that: described oxidizing reaction temperature is 190-240 DEG C.
10. according to the method described in claim 9, it is characterized in that: described oxidizing reaction temperature is 200-230 DEG C.
The method of 11. 1 kinds of highly selective silver catalyst catalyzed ethylene oxidation epoxy ethanes, it is characterized in that: wherein highly selective silver catalyst is to run well in oxidation of ethylene device but selectivity does not reach the catalyzer of desired value, in ethylene oxidation reactions gas, ethylene concentration is 20-40mol%, oxygen concentration is 6-8.5mol%, gas concentration lwevel is < 2mol%, the concentration of inhibitor regulates in 0.2-2ppmv, in reaction gas, add ethane makes its concentration be 0.1-1.5mol%, and all the other are for causing steady gas; And oxidizing reaction temperature is 180-260 DEG C; While add ethane in reaction gas, before or after by device interior reaction temperature reduce 5-20 DEG C; When reaching anticipation reaction selectivity, in 0.2-2ppmv, suitably improving inhibitor concentration, within the scope of 0.1-1.5mol%, suitably reducing ethane concentration simultaneously.
12. methods according to claim 11, is characterized in that: described anticipation reaction selectivity is 87 ~ 93mol%, described in be 3 ~ 20 days apart from adding the ethane time when reaching anticipation reaction selectivity.
13. methods according to claim 12, is characterized in that: described anticipation reaction selectivity is 88 ~ 91mol%, described in be 7 ~ 10 days apart from adding the ethane time when reaching anticipation reaction selectivity.
14. methods according to claim 11, is characterized in that: while add ethane in reaction gas, before or after by device interior reaction temperature reduce 6-15 DEG C.
15. methods according to claim 14, is characterized in that: while add ethane in reaction gas, before or after by device interior reaction temperature reduce 8-10 DEG C.
16. methods according to claim 11, is characterized in that: in reaction gas, add ethane make its concentration be 0.2-1.2mol%, reduce ethane concentration to 0.1-0.8mol% when reaching anticipation reaction selectivity.
17. methods according to claim 16, is characterized in that: in reaction gas, add ethane make its concentration be 0.4-0.8mol%, reduce ethane concentration to 0.2-0.4mol% when reaching anticipation reaction selectivity.
18., according to the method in claim 11 ~ 17 described in any one, is characterized in that: when using nitrogen for causing steady gas, oxygen concentration is 6-7mol%, and when using methane for causing steady gas, oxygen concentration is 7.5-8.5mol%; And described inhibitor is monochlorethane and/or ethylene dichloride.
19., according to the method in claim 11 ~ 17 described in any one, is characterized in that: described highly selective silver catalyst is that initial stage selectivity is greater than 82mol%; Most highly selective is greater than 86mol%; Latter stage, selectivity was greater than 82mol%; And space-time yield is the catalyzer that 160-280 gram of EO/ hour * rises.
20. methods according to claim 19, is characterized in that: described highly selective silver catalyst is greater than 87mol% for most highly selective; Latter stage, selectivity was greater than the catalyzer of 84mol%.
21., according to the method in claim 11 ~ 17 described in any one, is characterized in that: described oxidizing reaction temperature is 190-250 DEG C.
22., according to the method described in claim 21, is characterized in that: described oxidizing reaction temperature is 200-240 DEG C.
23., according to the method in claim 11 ~ 17 described in any one, is characterized in that: running well in described oxidation of ethylene device but the catalyzer that selectivity does not reach desired value is described highly selective silver catalyst has reached 1 ~ 12 month apart from the duration of service after device running at full capacity.
24. methods according to claim 23, is characterized in that: running well in described oxidation of ethylene device but the catalyzer that selectivity does not reach desired value is described highly selective silver catalyst has reached 3 ~ 10 months apart from the duration of service after device running at full capacity.
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| 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 |
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