CN103772179B - Unsaturated aldehyde process for selective oxidation - Google Patents

Abstract

The present invention relates to a kind of unsaturated aldehyde process for selective oxidation, adopt fixed bed reactors, reactor at least divides two conversion zones along reaction raw materials entrance to outlet, it is double-layer catalyst higher than the Mo-V of outer concentration that the first section of conversion zone that approaches reactor feedstocks entrance is equipped with internal layer concentration, approach that the latter end conversion zone of reactor outlet is in-built has a double-decker catalyst (I), from catalyst inner layer to outer chief component respectively by general formula (i) and (II) represent: Mo_aV_bW_cCu_dSi_eO_m（i），Mo_a′V_b′W_c′Cu_d′Ni_fSb_gA_hB_iO_x(II), the method is suitable can stably produce acrylic acid by long period.

Description

Unsaturated aldehyde process for selective oxidation

Technical field

The present invention relates to a kind of unsaturated aldehyde selective oxidation and prepare the method for unsaturated acids, as methacrylaldehyde or metering systemAldehyde selective oxidation is produced corresponding unsaturated acids, is particularly useful for methacrylaldehyde selective oxidation acrylic acid processed.

Background technology

Industrial main employing propylene two-step oxidizing process is prepared acrylic acid at present, and first propylene catalytic gas phase oxidation generates thirdOlefine aldehydr, methacrylaldehyde is reoxidised into acrylic acid. Acrolein oxidation reaction is strong exothermal reaction, in beds, can produce heatPoint, the heat that moment is gathered is constantly accumulated, by cause catalyst activity component loss, come off, to such an extent as under catalyst activityFall, the lost of life, and cause aggravating because of over oxidation reaction the formation of accessory substance, even cause runaway reaction, make catalystSintering.

" progress of oxidation acrylic acid synthesizing process and catalyst " (petrochemical industry, the 39th the 7th phase of volume in 2010) reportThe appearance of road focus also can make catalyst damage evil, shortens the service life of catalyst. Taking 80,000 tons/year of acroleic acid devices as example,Propylene oxidation is prepared in acrolein reaction device and is needed more than 2.5 ten thousand tubulation, and acrolein oxidation is prepared in acrylic acid reactor also to be neededWant more than 2.5 ten thousand tubulation, load altogether more than 100 ton of methacrylaldehyde, acrylic acid catalyst. More than 50000 reaction tube, the filling of catalyst is protectedCard does not fill empty certain difficulty that has, if because focus is crossed the very fast sintering of high catalyst, again change again in a short time agent, and can be pre-Think that its economic loss is huge; In addition, for methacrylaldehyde, acrylic acid production, under cryogenic conditions, enter as much as possibleOK, because reaction needed salt bath heating, its energy resource consumption that maintains production is also huge spending; Due to the generation of focus, to insteadShould pipe tubing require high temperature resistantly, for up to ten thousand reaction tubes, tubing expense be exactly the very large cost of item. Therefore, ifEffectively suppress the generation of beds focus, can bring huge economic benefit to large-scale industrial production.

The reaction unit that industrial methacrylaldehyde or methacrolein oxidation are prepared corresponding unsaturated aldehyde is mainly many reaction tubes,Ensureing that catalyst is not sintered, under the prerequisite of long service life, improve as far as possible selective and object product yield, save formerMaterial, if even if feed stock conversion, acrylic acid yield improve 0.1～0.5 percentage point, the amount of the product obtaining is with hundreds of～thousands ofThe level of ton increases, and its economic benefit is also very considerable.

At present, there is several different methods can reduce or avoid gathering and peroxidization of focus, can be from reaction unitImprovement two aspects of improvement and catalyst are considered. Aspect catalyst, as: Japanese patent laid-open 04-217932 has proposed onePlant the method for the hot polymerization collection on appearance or the focus that suppresses focus, by preparing the multiple catalysis with different possessive volumesAgent, and the mode reducing to outlet one side catalyst possessive volume from unstripped gas inlet side, fill successively reaction tube, but urgeThe possessive volume of agent is subject to the restriction of reaction tube diameter, and it is also very difficult that multiple catalysts is filled into reaction tube.US200421442A sneaks into heat resistanceheat resistant point to form catalyst is inert substance with by catalyst dilution in catalyst, Japanese Patent public affairsReport 36739/1987 is made catalyst the method for tubulose. There is again the catalyst that unstrpped gas porch reduces by active componentFilling. CN01121191.1 provides one to prepare acrylic acid, by tube-shell type fixed bed reactor gas phase catalysis oxygenChange the gas containing methacrylaldehyde, the method has effectively suppressed the generation of focus and has prepared with high yield acrylic acid. Described methodBe characterised in that each reaction tube is axially divided into at least three conversion zones along it, use than the catalyst of filling adjacent the second conversion zoneActive higher catalyst is filled first conversion zone near gas access, and with the catalyst filling of different activities level withAfter conversion zone, catalyst activity is raise to gas vent side continuously from the second conversion zone. This catalyst reaction temperaturesHigher, more than 240 DEG C, hot(test)-spot temperature is more than 300 DEG C substantially. CN200510007929.8 provides a kind of catalyzing proponeThe acrylic acid catalyst of aldehyde gaseous oxidation system, described catalyst comprises molybdenum and vanadium, also comprises at least one volatile catalyst poisonProperty composition, its amount is 10 to 100ppb quality through ion chromatography measurement, this catalyst can reduce the temperature of hot spot, andSuppress the reduction of the reaction efficiency of thermal degradation. Specific practice is to comprise with originally by the volatility toxic component that makes specified quantitativeHave in highly active catalyst, catalytic activity declines momently, can reduce the temperature of hot spot. CN97104224.1 is logicalAfter crossing catalytic active component being divided and is loaded on carrier, calcine the generation that the catalyst of load sharing suppresses focus, catalyst flatAll particle diameter is 4～16mm, and the average grain diameter of carrier is 3～12mm, and calcining heat is 500～600 DEG C. US2009415167A public affairsOpen a kind of method of producing unsaturated aldehyde and unsaturated acids, in reactor, pack two or more catalyst layer into, eachCatalyst layer by different holes density and or aperture size the catalyst of catalytic active component moulding fill, from reactor inletTo the particular table area of outlet catalytic active component increase gradually with control hole density and or aperture size, and then inhibitory reaction heatPoint. Even if CN200410007263.1 provides a kind of under the condition of formation focus, active, selective, the life-span is all good, long-termDemonstrate the catalyst of stability, and use the method for producing acrylic acid of this catalyst. Said catalyst is following logicalFormula (1) Mo_aV_bW_cCu_dA_eB_fC_gO_xRepresent. A is at least one that select from cobalt, nickel, iron, lead, bismuth, and B is from antimony, niobium, tinIn select at least one, C is at least one that select from silicon, aluminium, titanium, zirconium. This catalyst can not effectively suppress catalystEmerging of bed focus. Under higher focus condition, reaction unit requires to have superpower resistance to elevated temperatures, and after reactionContinuous separate, to absorb process operations expense also very high. CN200410048021.7 discloses a kind of O composite metallic oxide catalyst, urgesAgent be by 1. molybdenum, vanadium, copper main active component and 2. requisite at least by the stable component of antimony and titanium and 3. nickel,The composite oxides of iron, silicon, aluminium, alkali metal, alkaline-earth metal composition. 2. and 3. wherein within the scope of 900 DEG C, to roast at 120 DEG CFire standby composite oxides. This catalyst shows the permanent stability under high activity and good selectivity.CN201010180103.2 discloses a kind of multilayer composite metal oxide catalyst, the composition of this O composite metallic oxide catalystCan be by formula M o_aBi_bNi_cCs_dCu_eTi_fA_gB_hC_iO_jRepresent, described O composite metallic oxide catalyst has sandwich construction, fromInternal layer parent reduces successively to outer each concentration of element, even if catalyst initial reaction activity is very high, this catalyst can be effectiveReduce single tube reactor localized heat and gather, suppress emerging of focus. This catalyst is mainly to control because catalyst initial activity is highAnd the focus producing. But the selective and yield of object product has much room for improvement. And in long week of the mixed airflow such as propylene, steamUnder phase Scouring Condition, catalyst surface active component has part to run off, and affects catalyst activity and stability.CN201010180184.6 provides a kind of three layers of multi-metal-oxide catalyst and preparation method thereof, and this catalyst contains multiple goldBelong to oxide as active component, this catalyst is applicable to propylene or corresponding unsaturated aldehyde is produced in selective isobutene oxidation,Can effectively suppress to generate compared with high focus because the organic matter of unstripped gas middle and high concentration contacts with the catalyst initial stage to formA large amount of accessory substances, improves catalyst selectivity. These three layers of catalyst are easy to come off through long-term operation skin, increase catalysisAgent bed resistance, thus active decline caused. And the selective and yield of this catalyst object product also has much room for improvement.

All there is a problem in the method that above-mentioned inhibition focus produces, is filled into catalyst in reaction tube from entrance to going outMouthful be all diluted with various forms, both made catalyst runs some cycles after active decline also can not change thinner ratio, urgeAgent also cannot provide higher activity again, not only loads, dismantles, separates, reclaims catalyst and make troubles, and can reduce and urgeThe reactivity of agent, especially industrial long-term operation catalyst activity reduction is faster, affects catalyst life.

CN101274279 discloses a kind of oxide catalyst, Mo₁₂V_gW_hCu_iE_jF_kG_lH_mO_y(3) (wherein Mo is molybdenum, and V isVanadium, W is tungsten, and Cu is copper, and E is at least the element that is selected from cobalt, nickel, iron, lead and bismuth, and F is at least the element that is selected from antimony, niobium and tin, GBe at least the element that is selected from silicon, aluminium, titanium and zirconium, H is selected from alkali-metal element, and O is oxygen; G, h, i, j, k, l, m and y areThe corresponding atomic ratio of V, W, Cu, E, F, G, H and O, it is respectively 2≤g≤15,0≤h≤10,0 < i≤6,0≤j≤30,0≤k≤ 6,0≤l≤60,0≤m≤6, and y is the numerical value definite by the oxidation state of respective element). This invention for solve due toThe appearance of catalyst focus and cause it active or selectively due to sintering etc. and significantly reduced problem. This invention is such solutionThe technical problem of determining, the catalyst packing in reactor has specific particle size distribution, the space between catalyst granulesCan be by evenly and expand, can suppress the appearance of local extra high temperature spot (focus) in catalyst layer and do not reduce propyleneAldehyde or acrylic acid output, and can obtain long-term and stably methacrylaldehyde or acrylic acid. This catalyst particle size is relativeStandard deviation is 0.02～0.20. Because industrial methacrylaldehyde, acrylic acid production loaded catalyst are larger, want to ensure catalysisThe particle size relative standard deviation of agent is 0.02～0.20, can restrict undoubtedly the large-scale production of catalyst, may produceCheng Zhonghui is the useless agent processing of conduct because of the irregularity of catalyst size. And tons of catalyst, screening particle size is relativeStandard deviation is that the work of 0.02-0.20 is also wasted time and energy very much. CN200980112659.3 discloses a kind of following component of comprisingCoated catalysts: (a) carrier, the ground floor of the precursor compound that (b) comprises molybdenum oxide or formation molybdenum oxide, (c) comprisesContain the second layer of the poly-metal deoxide of molybdenum and at least one other metal. Preferably the molybdenum oxide of ground floor is MoO₃, secondThe poly-metal deoxide of layer is the poly-metal deoxide that general formula I I represents: Mo₁₂Bi_aCr_bX¹ _cFe_dX² _eX³ _fO_y. This catalyst is bagDraw together the application type catalyst of carrier. Goal of the invention is that inhibition heterogeneously catalysed partial gas phase oxidation methacrylaldehyde is acrylic acid coatingCatalysqt deactivation, has improved inactivation performance. This invention is not clearly recorded catalyst for catalyzing propone oxidation system thirdOlefine aldehydr, acrylic acid reactivity worth evaluating data, such as conversion ratio, selective, yield etc. The open one of CN1121441 is used forBy methacrylaldehyde or to carry out oxidation reaction production containing the gas of acrolein gas and a kind of molecule-containing keto in vapour phase acrylic acidCatalyst, this catalyst comprises (A) a kind of composite oxides, has molybdenum and vanadium as base stock, and is suitable for urging by vapour phaseChange propylene oxide aldehyde to produce acrylic acid, and (B) a kind of solid peracid, its acid strength (Ho) be not more than-11.93 (Ho≤-11.93). This invention adopts molybdenum vanadium type composite oxides and a kind of acid strength to be no more than-11.93 solid acid and combines, raisingThe low temperature high activity of catalyst. CN200610073671.6 discloses the carrier that a kind of gas-phase oxidation catalyst is used, described carrier bagContaining its acid strength (H₀) meet inequality :-5.6≤H₀≤ 1.5 solid acid; A kind of gas-phase oxidation catalyst, it carries above comprisingBody and comprise molybdenum and the vanadium composite oxides as solvent, described composite oxides are carried on described carrier;Catalytic gas phase oxidation by methacrylaldehyde and molecular oxygen is prepared acrylic acid. Prepare a method for carrier above, described method bagDraw together the acid strength (H that controls solid acid by being adjusted in calcining heat in the preparation that is contained in the solid acid in carrier₀), withJust meet inequality :-5.6≤H₀≤ 1.5. CN200510059468.9 discloses a kind of acrylic acid catalyst for producing, its featureThat the oxide of the metallic element composition representing at following formula M oaVbWcCudOx (1) and/or composite oxides are for urgingIn the acrylic acid catalyst for producing of agent composition, need to control tungsten and be partially the face side of this catalyst, and/or copper is partiallyThe core side of this catalyst, to improve catalyst activity. Tungsten is the face side of this catalyst partially, and/or copper is this catalysis partiallyThe core side of agent is difficult to accurately control.

CN102039143A discloses the preparation method that a kind of acrolein oxidation is prepared acrylic acid catalyst, a) combined oxidationThe preparation method of thing coating: the water-soluble metal salt that contains Mo, V, W, Cu, Sb composition is dispersed in to water/have in 30-100 DEG CIn machine phase mixed system; Keeping organic solvent and water weight ratio is 5～50%; Reaction generates composite oxides presoma slurries;Make catalyst activity component through distillation, oven dry, roasting again; B) above-mentioned active component chief component element, be selected from Mo, V,Cu, W, Sb wherein one or more; Wherein active component represents by following formula: Mo_aV_bCu_cW_dSb_eO_f, in formula, a～f represents respectivelyThe atomic ratio of element, in the time of a=12, b=0～10, c=0～6, d=0～10, e=0～0.5, f meets other element states of oxidationValue. This catalyst adopts the mixed system preparation of water and lower alcohol, and catalyst has higher specific area and specialMicrostructure, has compared with high-ratio surface and difficult drop-off, and bearing capacity can reach 50% and more than, solve application type catalystThe problem that service life is shorter.

CN1647854 discloses a kind of catalyst of selectively oxidizing methyl acrylic aldehyde to synthesize methyl propenoic acid, this catalystComposition general formula is: x (Mo₁₂P_aK_bSb_cCu_dAs_eA_fD_gQ_hO_iMo_j)/yZ, Z is carrier dilution thermal conducting agent; Mo, P, K, Sb, Cu and AsBe respectively molybdenum, phosphorus, potassium, antimony, copper and arsenic; A represents at least one element in tungsten W, vanadium V, niobium Nb, iron Fe and plumbous Pb; D represent boron,At least one element in gallium Ga, indium In, germanium Ge and silicon Si; Q represents at least one element in rubidium Rb, caesium Cs and thallium Tl, this inventionOn the one hand by adding Sb, Cu and As to improve the activity and selectivity of catalyst; On the other hand by adding MoO₃And carrierHeat conduction diluent improves heat endurance, heat conductivility and the mechanical strength of catalyst, effectively suppresses active component heteropoly acidThe decomposition of salt and reduce beds hot(test)-spot temperature, avoids the loss of Mo and As, extending catalyst service life. Similarly alsoThere is CN101579631, CN101850259ACN101850259A. CN1874984 is open a kind of by effectively controlling hot(test)-spot temperatureAnd stably use catalyst to prepare the method for unsaturated aldehyde and/or unrighted acid with high yield simultaneously, it is characterized in that:Described reactor comprises the reaction zone of preparing unsaturated aldehyde, and this reaction zone comprises two-layer or multilayer Catalytic Layer, and each Catalytic Layer is all filled outBe filled with the shaped catalyst product as secondary, wherein the secondary in each Catalytic Layer is by having varigrained catalysisThe primary particle of active component forms, and control described catalytic active component primary particle granularity so that this granularity from reactionDevice entrance to reactor outlet reduces. This invention is hot issue in order to control catalyst, and this invention is by controlling catalysisThe size of agent particle suppresses focus, and the Catalytic Layer of the primary particle of maximum sized catalytic active component comprises that temperature is the highestFocus, and the size range of described primary particle is 10 to 150 microns.

In addition, under hot conditions, in catalyst, part active component molybdenum loses because of distillation from catalyst surface. PropyleneThe washing away of mixed airflow such as aldehyde, air (oxygen), nitrogen and steam also can make the loss of active component in catalyst. For suppressingThe loss of molybdenum distillation causes active decay, and CN1121504 is by mixing copper component and having specified particle diameter and specific areaZirconium and/or titanium and/or cerium, can suppress dissipation effect and the over reduction of molybdenum composition; CN1445020 adds a small amount of tellurium to play surelyFixed free molybdenum trioxide and the effect of molybdic acid copper crystal structure, sublimation and the over reduction of molybdenum suppress to some extent;CN1583261 is taking molybdenum, vanadium, copper, tungsten and/or niobium as key component, with composite oxides or its oxide of other element formationCompositions of mixtures catalyst suppress the loss of molybdenum.

The invention provides a kind of unsaturated aldehyde process for selective oxidation, under low temperature, high-load condition, react, andImprove as far as possible the selective and yield of object product, to obtain larger economic benefit.

Summary of the invention

The object of this invention is to provide a kind of unsaturated aldehyde process for selective oxidation, especially methacrylaldehyde or MALSelective oxidation is produced the method for corresponding unsaturated acids. Particularly suitable methacrylaldehyde selective oxidation is prepared acrylic acid.

A kind of unsaturated aldehyde process for selective oxidation, adopts fixed bed reactors, and reactor is along reaction raw materials entrance to going outMouth at least divides two conversion zones, and the first section of conversion zone that approaches reactor feedstocks entrance is equipped with the Mo-V of internal layer concentration higher than outer concentrationBe double-layer catalyst, as the catalyst of CN201110265250.4, approach the latter end conversion zone of reactor outlet in-built have twoLayer structure catalyst (I), is (i) represented with (II) by general formula respectively to outer chief component from catalyst inner layer.

Mo_aV_bW_cCu_dSi_eO_m（i）

Mo_a′V_b′W_c′Cu_d′Ni_fSb_gA_hB_iO_x（ⅱ）

Wherein: Mo is molybdenum, V is alum, and W is tungsten, and Cu is copper, and Ni is nickel, and Sb is antimony, and Si is silicon, and silicon is to add in catalystCarrier, A is at least one element being selected from potassium, titanium, zirconium; B is at least one element being selected from magnesium, iron, lanthanum; O is oxygen;A, b, c, d, a ', b ', c ', d ', e, f, g, h, i represent respectively each element atomic ratio, and wherein a, a ' they are numbers of 12-14, b,B ' is a number of 2-7, preferably 2-5; C, c ' are numbers of 1-5, preferably 1-3.5; D, d ' are numbers of 1-6, preferably1.5-4; E is a number of 5-45, and f is a number of 0.5-5, and g is a number of 0.1-5, and h is a number of 0.1-2.5, iBe a number of 0.1-3.5, m, x are the numerical value being determined by the oxygen of each oxide.

A method for unsaturated aldehyde selective oxidation, adopts fixed bed reactors, and reactor along reaction raw materials entrance extremelyOutlet point S₁Section and S₂Section, S₁It is double-layer catalyst higher than the Mo-V of outer concentration that section is equipped with internal layer concentration, asThe catalyst of CN201110265250.4, S₂Section reactor is in-built has a double-deck catalyst of the present invention (I). Along raw materialArrival end to port of export beds porch to 1/3 or porch to the scope filling internal layer concentration between 1/2 place higher thanThe Mo-V of outer concentration is double-layer catalyst, and as the catalyst of CN201110265250.4, the filling scope of catalyst does not addStrictly to limit, can be less than 1/3 of beds, also can unnecessary 1/3. S₂In section reactor, filling chief component is by leading toFormula (i) and (II) represent catalyst (I).

A method for unsaturated aldehyde selective oxidation, reactor is along reaction raw materials entrance to outlet point S₁Conversion zone, S₂InsteadShould section and S₃Conversion zone, S₁It is double-layer catalyst higher than the Mo-V of outer concentration that conversion zone is equipped with internal layer concentration, asThe catalyst of CN201110265250.4, S₃Conversion zone reactor is in-built have chief component by general formula (i) and (II) representDouble-decker catalyst (I). S₂Conversion zone is equipped with S₁Section (is S₁Conversion zone) and S₃Section (is S₃Conversion zone) two-stage catalytic agentMixed catalyst. S₁Conversion zone length is less than 1/3 of total reactor length, S₂Conversion zone length is less than total reactor length1/3，S₃Conversion zone length is less than 1/2 of total reactor length. S₂The ratio of conversion zone mixed catalyst meets following condition: 0.5＜≤ 2. Wherein, internal layer concentration is double-layer catalyst volume (V lower than the Mo-V of outer concentration₂), internal layer concentration higher than outsideThe Mo-V of layer concentration is double-layer catalyst volume (V₁）。

A method for unsaturated aldehyde selective oxidation, the process conditions of oxidation reaction are in addition restriction especially, as canAdopt following process conditions: reaction raw materials methacrylaldehyde, water, oxygen more than 180 DEG C enter reactor after preheating through preheater, salt bathHeating, 240～260 DEG C of salt temperatures, preferably 240～250 DEG C; Air speed 800～2000h^-1, preferably 800～1800h^-1, chargingComposition: methacrylaldehyde 8～12 volume %, steam 11～17%, oxygen 9～17 volume %, nitrogen 58～71 volume %.

Used catalyst of the present invention has multilayer structure, i.e. interior outer double-layer structure, outside internal layer catalyst key component is less thanLayer key component, in molar content, the each constituent content concentration ratio of catalyst outer layer internal layer parent is high. The concentration of ectonexineDifference can be by adjusting the Numerical Implementation such as a, b, c, d, a ', b ', c ', d ', e, f, g, h, i, as the numerical value of a, b, c, d is less than correspondingThe value of a ', b ', c ', d '. Or add the materials such as different amount silica, aluminium oxide, carborundum at ectonexine.

The multilayer structure catalyst that the present invention is used, can by add at ectonexine different amount silica, aluminium oxide,The materials such as carborundum are achieved concentration difference, that is to say, one or more in outer silica, aluminium oxide or carborundumMolar concentration rate internal layer parent low, in molar content, outer each active component constituent content contains than this element of internal layerMeasure high by 0.1～30%, preferably 0.1～18%.

Methacrylaldehyde selective oxidation acrylic acid processed is because reaction temperature is substantially more than 270 DEG C, and long period is at such heightUnder temperature reaction condition, the active component molybdenum in catalyst is easy to run off because of distillation. Preferably lanthanum of B in catalyst of the present invention,Lanthanum and molybdenum, nickel, copper, antimony etc. can form stable crystal phase structure, as Cu₂La、LaNi₅、LaSb、La₅Sb₃Deng, be conducive to suppressPart active component molybdenum loses because of distillation from catalyst surface, and before and after catalyst reaction, active component molybdenum content is substantially constant,Delay active deterioration rate, catalyst stability is good. Lanthanum and molybdenum, vanadium ratio are suitable, and in general formula (I), B is lanthanum, and i is 0.1～3.5A number, too much the membership that adds of lanthanum is competed molybdenum with vanadium and nickel, for example too much lanthanum adds may affect active phase VMo₃O₁₁To MoO₃Crystallization is shifted, and affects catalyst activity. The preferred lanthanum nitrate in lanthanum of the present invention source. Catalyst outer layer chief component is by general formula(II) represents: Mo_a′V_b′W_c′Cu_d′Ni_fSb_gA_hLa_iO_x（ⅱ）。

Used catalyst of the present invention has double-decker, and internal layer also can be called internal layer parent. The catalysis that the present invention is usedAgent adopts common preparation method, as adopted following step preparation.

1) compound that contains Mo, V, W, Cu dissolved and mixed, carrying out forming internal layer parent slurries after co-precipitation,Add again one or more of the materials such as silica, aluminium oxide, carborundum, drying, moulding, roasting obtains catalyst inner layer motherBody;

2) prepare outer layer catalyst according to the method for Kaolinite Preparation of Catalyst internal layer parent, in outer layer catalyst preparation process, addOne or more of the materials such as silica, aluminium oxide, carborundum, make in outer layer catalyst each concentration of element than this yuan of internal layerThe concentration of element is high;

3) outer layer catalyst of preparation is coated on catalyst inner layer parent successively, after roasting, obtains finished catalyst.

Used catalyst internal layer parent of the present invention is after moulding and outer after coating, all need at 300～550 DEG C, roastBurn 3～10h, compare not the catalyst of roasting respectively, repeatedly roasting can improve activity and the stability of catalyst. Ectonexine roastingTemperature is preferably identical. Can be that open roasting can be also enclosed roasting, calcination atmosphere can be helium, nitrogen, argon gasDeng inert gas. Catalyst layer easily chaps when thick roasting very much, for fear of be full of cracks be preferably in apply after 55～120 DEG C of oven dry,And then roasting. The outer layer catalyst bed thickness that is coated on internal layer parent is 0.1～2.0mm, preferably 0.1～1.5mm.

The compound of each component of used catalyst of the present invention can use nitrate, ammonium salt, the sulfuric acid of each elementSalt, oxide, hydroxide, chloride, acetate etc. As ammonium molybdate, ammonium metavanadate, magnesium nitrate, ammonium paratungstate, nickel nitrate,Nickelous carbonate, lanthanum nitrate, ferric nitrate, basic copper carbonate, copper nitrate, antimony oxide, potassium nitrate, titanium oxide, zirconia etc.

After used catalyst internal layer parent slurries of the present invention are dried, conventionally preferably adopt extrusion molding, granulating and forming, compressing tabletThat the forming methods such as moulding are processed into is spherical, hollow spheres, ellipticity, cylindric, hollow circuit cylinder etc., preferably hollow circuit cylinder or ballShape.

When used catalyst of the present invention applies, preferably use binding agent, make ectonexine catalyst bonding more firm. ?Internal layer parent sprays binding agent and infiltrates surface under rolling condition, then sprays the outer layer catalyst powder preparing, and also canInternal layer parent is put into the outer layer catalyst slurries that the prepare coating of rolling. Binding agent is selected from water, alcohols or ethersOne or more. Alcohols is as ethanol, propyl alcohol, butanols; Ethers is as ether and butyl ether.

Preferably uneven, the rough surface of each layer of surface of used catalyst of the present invention, be conducive to apply, ectonexine itBetween bonding more firm.

The present invention is in order to improve intensity, the efflorescence degree of catalyst, can in above-mentioned outer layer catalyst, add glass fibre,In graphite, pottery or various whisker one or more.

Used catalyst of the present invention can directly use, and also can be carried on inert carrier and use. Related inert carrierIt can be one or more mixture of aluminium oxide, silica, carborundum etc.

Because catalyst initial reaction activity is very high, so be easy to produce focus on fixed bed single tube reactor bedOr generation heat localization, catalyst is easy to sintering, and this loses concerning suitability for industrialized production methacrylaldehyde acrylic acid is very serious. FormerIn material, pass into a certain amount of steam, because specific heat of water is large, can take away a large amount of reaction heat, but steam input greatly often makes to urgeAgent part active component solution-off and make active decline. Therefore need catalyst to there is good water repelling property. The present invention is bestUse two kinds and there is double-deck multi-metal-oxide catalyst, at methacrylaldehyde Way in, first use internal layer concentration higher thanThe catalyst of outer concentration, because the active component concentration of catalyst outer surface is low, so corresponding activity is also low, therefore can haveEffect suppresses emerging of focus and gathering of heat, reduces the growing amount of accessory substance (as hydrocarbon), raising object productSelectively. Use internal layer concentration lower than the catalyst of outer concentration or point three sections of fillings at residual catalyst bed, urge at two kindsBetween agent, use the mixture of two kinds of catalyst, methacrylaldehyde relative concentration entrance is lower, and catalyst activity is high, makes catalystBed temperature distributes rationally, is more conducive to improve acrylic acid selective and yield. And catalyst structure is stable, active groupDivide the difficult losses such as molybdenum. Like this, under high-speed reaction condition, two kinds have double-deck catalyst layering filling, catalysisIt is more reasonable that agent bed temperature distributes, and avoids approaching fast (the bed temperature decline impact of reaction bed temperature decline of the port of exportSelective and the yield of catalyst, is unfavorable for the steady running of catalyst long period), make catalyst there is good water-resistanceCan, improve the selective and yield of object product.

Detailed description of the invention

Illustrate that with specific embodiment methacrylaldehyde selective oxidation prepares acrylic acid below, and but model of the present inventionEnclose and be not limited to these embodiment. The analytical method of product composition adopts this area universal method.

Embodiment 1:

Under stirring condition, get 39.7 grams of 239.4 grams of ammonium molybdates, ammonium metavanadates, be dissolved in (water temperature 65 in 1000ml pure waterMore than DEG C), obtain slurries (1), then get 59 grams of ammonium paratungstates, 39.4 grams of copper nitrates are dissolved in (65 DEG C of water temperatures in 500ml pure waterAbove), be fully uniformly mixed, obtain slurries (2). Then, slurries (1) mix with slurries (2), obtain slurries (3), obtainActive component slurries (a). In active component slurries (a), add 94.9 grams of silica and 3.3 grams of graphite, 80 DEG C of strong stirringsCarry out heat drying after coprecipitation reaction, with 160 DEG C of heat treatments 3 hours, be then φ through banded extruder extrusion modling in nitrogenThe hollow columnar particle of 4.5 × 5mm, dries rear 450 DEG C of roastings 5 hours, makes catalyst Precursors, this catalyst inner layer for 110 DEG CParent chief component is: Mo₁₂V₃W₂Cu_1.5Si₁₄O_m（i）。

Under stirring condition, get 66.1 grams of 279.3 grams of ammonium molybdates, ammonium metavanadates, be dissolved in (water temperature 65 in 1000ml pure waterMore than DEG C), obtain slurries (1), then get 88.5 grams of ammonium paratungstates, 63.1 grams of copper nitrates, 42.7 grams of nickel nitrates, 13.4 grams of nitric acidPotassium, 47.7 grams of lanthanum nitrates are dissolved in (water temperature is more than 65 DEG C) in 1000ml pure water, are fully uniformly mixed, and obtain slurries (2).Then, slurries (1) mix with slurries (2), obtain active component slurries (a), in active component slurries (a), add 8.8 gram twoSilica, 184.5 grams of antimony oxides, 85 DEG C of strong stirrings carry out heat drying after coprecipitation reaction, in nitrogen with 160 DEG CHeat treatment 3 hours, 500 DEG C of roastings 4 hours, process to obtain catalyst outer layer powder through pulverizing, grind, sieving. This catalyst outer layerChief component is: Mo₁₄V₅W₃Cu_2.4Ni_1.3Sb_2.8K_0.6La_1.3Si_1.3Ox（ⅱ）。

Catalyst inner layer parent is placed in to round bottom container, under container rotation condition, sprays ethanol to catalyst Precursors moltenLiquid stops operating under the condition of fully wetting catalyst inner layer parent, and the skin that is placed with that puts it into rapidly another rotation is urgedIn the round bottom container of agent powder, apply, coating layer thickness is at 1.0～2.0mm, after 105 DEG C of oven dry of gained catalyst through 450DEG C roasting obtains catalyst 1 for 4.5 hours. Outer field each constituent content is higher by 1.9%～8.8% than this constituent content of internal layer.

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermocouple, packs into along methacrylaldehyde feedstock direction reactor bed17mlCN201110265250.4 catalyst 5(S₁Section), the above-mentioned catalyst of 23ml or comparative example catalyst (S₂Section), salt bath addsHeat, 246 DEG C of salt temperatures. From above-mentioned reaction tube porch with air speed 1300h^-1Methacrylaldehyde 10 volume %, air 14 volume %, waterThe mist of steam 15 volume %, nitrogen 61 volume %. React beds S 24 hours₂Section hot localised points temperature 278DEG C, acrolein conversion rate is 98.9%, acrylic acid is selective 90.9%, acrylic acid yield 89.4%. Adopt two kinds of double-layer catalysts to divideSection filling, compares a kind of catalyst of independent filling, and reaction bed temperature calibration is more reasonable, has improved object selectivity of productAnd yield. The selective relative mistake of comparative example 1,2, acrylic acid yield is low. After the oxidation reaction 1000h of embodiment 1, bed S₂Section officePortion's hot(test)-spot temperature is 276 DEG C～278 DEG C, and acrolein conversion rate is 99.0%, and acrylic acid is selective 90.8%, acrylic acid yield89.5%. The difficult losses such as catalyst activity component molybdenum, stable performance, has good water repelling property, methacrylaldehyde selective oxidationReaction long period stably carries out.

Comparative example 1:

Taking the internal layer parent of catalyst 1 as comparative catalyst 1, banded extruder extrusion modling is the hollow columnar of φ 5 × 5mmGrain, methacrylaldehyde selective oxidation reaction is with embodiment 1. React 24 hours S₂280 DEG C of section hot localised points temperature, acrolein conversion rateBe 99.0%, acrylic acid is selective 88.3%, acrylic acid yield 86.6%.

Comparative example 2:

Taking the skin of catalyst 1 as comparative catalyst 2, banded extruder extrusion modling is the hollow columnar particle of φ 5 × 5mm,Methacrylaldehyde selective oxidation reaction is with embodiment 1. React 24 hours S₂283 DEG C of section hot localised points temperature, acrolein conversion rate is98.8%, acrylic acid is selective 87.8%, acrylic acid yield 86.1%.

Embodiment 2:

The preparation of catalyst 2

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 122 grams of silica and 3.5 gramsCarborundum, is a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, and skin adds 20.3 grams of silica. CoatingThickness, at 0.5～2.0mm, obtains catalyst 2 for 4.5 hours through 500 DEG C of roastings. Catalyst 2 internal layer parent chief components are:Mo₁₃V₂W₁Cu₁Si₁₈O_m, outer chief component is:

Mo₁₄V₅W_2.5Cu_3.2Ni_3.4Sb_1.6Ti_1.0Mg_0.5La_0.8Si₃O_x（ⅱ）

Outer field each constituent content is higher by 1.4%～8.6% than this constituent content of internal layer.

Pack 12mlCN201110265250.4 catalyst 3(S into along feedstock direction reactor bed₁Section), 17ml is above-mentioned to be urgedAgent 2(S₃Section), at S₁With S₃Between section, be provided with S₂Section, S₂Section is equipped with the mixture 11ml of above-mentioned two kinds of catalyst,CN201110265250.4 catalyst 3 mixes than 1:2 by same volume with catalyst 2, salt bath heating, 250 DEG C of salt temperatures. From upperState reaction tube porch with air speed 1650h^-1Enter methacrylaldehyde 10 volume %, oxygen 14 volume %, steam 17 volume %, nitrogenThe mist of 59 volume %. React 24 hours beds S₂275 DEG C of section hot localised points temperature, S₃Section hot localised points temperature280 DEG C, acrolein conversion rate is 99.3%, and acrylic acid is selective 91.0%, acrylic acid yield 89.6%. Reaction bed temperature dividesIt is more reasonable to spend, and has improved object selectivity of product and yield. After the oxidation reaction 1000h of embodiment 2, beds S₂Section274～276 DEG C of hot localised points temperature, bed S₃Section hot localised points temperature is 279 DEG C～281 DEG C, and acrolein conversion rate is99.1%, acrylic acid is selective 90.8%, acrylic acid yield 89.4%. The difficult losses such as catalyst activity component molybdenum, stable performance,Have good water repelling property, methacrylaldehyde selective oxidation reaction long period stably carries out.

Embodiment 3:

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 57.5 grams of silica and 3.2Gram graphite, is the hollow columnar particle of φ 5 × 5mm through banded extruder extrusion modling, and skin adds 28.5 grams of silica. Thick coatingDegree, at 0.1～1.5mm, obtains catalyst 3 for 6 hours through 400 DEG C of roastings. Catalyst 3 internal layer parent chief components are:Mo₁₂V_2.5W_1.2Cu₃Si₃₅O_m(i); Outer chief component is:

Mo₁₃V₇W₅Cu₆Ni_0.6Sb_4.8Zr_0.3La₃Si₁O_x（ⅱ）

Outer field each constituent content is higher by 0.7%～12.4% than this constituent content of internal layer.

Pack 13mlCN201110265250.4 catalyst 1(S into along feedstock direction reactor bed₁Section), 16ml is above-mentioned to be urgedAgent (S₃Section), at S₁With S₃Between section, be provided with S₂Section, S₂Section is equipped with the mixture 11ml of above-mentioned two kinds of catalyst,CN201110265250.4 catalyst 1 mixes than 2:3 by same volume with catalyst 3, salt bath heating, 243 DEG C of salt temperatures. From upperState reaction tube porch with air speed 900h^-1Enter methacrylaldehyde 9 volume %, oxygen 13 volume %, steam 16 volume %, nitrogen 62The mist of volume %. React 24 hours beds S₂271 DEG C of section hot localised points temperature, S₃Section hot localised points temperature 274DEG C, acrolein conversion rate is 99.0%, acrylic acid is selective 90.5%, acrylic acid yield 88.9%. Reaction bed temperature calibration moreAdd rationally, improved object selectivity of product and yield. After the oxidation reaction 1000h of embodiment 3, beds S₂Section is local270～271 DEG C of hot(test)-spot temperatures, bed S₃Section hot localised points temperature is 274 DEG C～276 DEG C, and acrolein conversion rate is 99.1%, the thirdOlefin(e) acid is selective 90.2%, acrylic acid yield 89.2%. The difficult losses such as catalyst activity component molybdenum, stable performance, has fineWater repelling property, methacrylaldehyde selective oxidation reaction long period stably carries out.

Embodiment 4:

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 97.7 grams of silica and 2.5Gram aluminium oxide, then through banded extruder extruding, rolling is a granulated into the ball shape that diameter is 2mm, skin adds 13.4 grams of titanium dioxideSilicon. Coating layer thickness, at 0.5～2.0mm, obtains catalyst 4 for 5 hours through 480 DEG C of roastings. Catalyst 4 internal layer parent chief componentsFor: Mo₁₂V_2.6W_1.5Cu_1.2Si₂₅O_m(i), outer chief component is: Mo₁₄V₆W₄Cu_4.8Ni_1.3Sb_0.8K_0.6Fe_0.1La_2.2Si_1.2O_x（ⅱ）

Outer field each constituent content is higher by 0.3%～15% than this constituent content of internal layer.

Pack 12mlCN201110265250.4 catalyst 5(S into along methacrylaldehyde feedstock direction reactor bed₁Section), 18mlAbove-mentioned catalyst (S₂Section), salt bath heating, 252 DEG C of salt temperatures. From above-mentioned reaction tube porch with air speed 1900h^-1MethacrylaldehydeThe mist of 11 volume %, oxygen 15 volume %, steam 15 volume %, nitrogen 59 volume %. React catalyst 24 hoursBed S₂281 DEG C of section hot localised points temperature, acrolein conversion rate is 99.3%, acrylic acid is selective 90.6%, acrylic acid yield89.4%. Adopt two kinds of double-layer catalyst segmentation fillings, compare a kind of catalyst of independent filling, reaction bed temperature calibration moreAdd rationally, improved object selectivity of product and yield. After the oxidation reaction 1000h of embodiment 4, bed S₂Section hot localised points temperatureDegree is 279 DEG C～282 DEG C, and acrolein conversion rate is 99.1%, and acrylic acid is selective 90.7%, acrylic acid yield 89.5%. CatalystThe difficult losses such as active component molybdenum, stable performance, has good water repelling property, and methacrylaldehyde selective oxidation reaction long period is steadySurely carry out.

Embodiment 5:

Loading catalyst 4 separately, methacrylaldehyde selective oxidation reaction is with embodiment 4. React 24 hours S₂Section hot localised points283 DEG C of temperature, acrolein conversion rate is 99.1%, acrylic acid is selective 87.9%, acrylic acid yield 86.5%. Hot(test)-spot temperature is high, pairReaction is serious, acrylic acid poor selectivity, and yield is low.

Comparative example 3:

Separately filling CN201110265250.4 embodiment 5 catalyst, methacrylaldehyde selective oxidation reaction is with implementingExample 1. React 24 hours S₂273 DEG C of section hot localised points temperature, acrolein conversion rate is 98.3%, acrylic acid selective 87.9%, the thirdOlefin(e) acid yield 85.3%.

Claims (13)

1. a unsaturated aldehyde process for selective oxidation, described method is prepared acrylic acid for methacrylaldehyde, adopts fixed bed reactionDevice, is characterized in that reactor at least divides two conversion zones along reaction raw materials entrance to outlet, approaches the head of reactor feedstocks entranceIt is double-layer catalyst higher than the Mo-V of outer concentration that section conversion zone is equipped with internal layer concentration, and the chief component of this catalyst is by leading to belowFormula (I ') represent: Mo_aV_bW_cNi_dA_eB_fSi_gO_x(I '), wherein Mo is molybdenum, and V is vanadium, and W is tungsten, and Ni is nickel, A is selected from copper, cobalt, manganeseIn at least one element; B is at least one element in selected among zirconium, strontium, lanthanum, magnesium and titanium; Si is silicon, and silicon is carrying of addingBody, O is oxygen; A, b, c, d, e, f, g represent respectively each element atomic ratio, wherein a=12, and b is a number of 3～10, c is 0.5A number of～5, d is a number of 1～5, and e is a number of 0～3, and f is a number of 0～3, and g is 0.5～30 oneNumber, x is the numerical value being determined by the oxygen of each oxide, described catalyst (I ') there is interior outer double-layer structure, every layer of catalyst is mainForm identically, but one or more total content difference in silica or carborundum, in outer silica or carborundumOne or more total content than the height of internal layer parent, in molar content, the each constituent content concentration of catalyst outer layerLower than internal layer parent; Approach that the latter end conversion zone of reactor outlet is in-built has a double-decker catalyst (I), from catalyst (I)Internal layer is represented by general formula (I) and (II) respectively to outer chief component: Mo_aV_bW_cCu_dSi_eO_m(ⅰ)，Mo_a′V_b′W_c′Cu_d′Ni_fSb_gA_hB_iO_x(II), wherein: silicon is carrier, A is at least one element being selected from potassium, titanium, zirconium; B is selected from magnesium, iron, lanthanumIn at least one element; O is oxygen; A, b, c, d, a ', b ', c ', d ', e, f, g, h, i represent respectively each element atomic ratio, whereinA, a ' are numbers of 12-14, and b, b ' are numbers of 2-7, and c, c ' are numbers of 1-5, and d, d ' are numbers of 1-6, and e isA number of 5-45, f is a number of 0.5-5, and g is a number of 0.1-5, and h is a number of 0.1-2.5, and i is 0.1-3.5A number, m, x are the numerical value being determined by the oxygen of each oxide, add in different amount silica or carborundum at ectonexineOne or more make catalyst (I) have gradient difference from inside to exterior active combination of components substrate concentration, with molar contentMeter, outer each constituent content is higher by 0.1～30% than this constituent content of internal layer parent.

2. method according to claim 1, is characterized in that reactor is along reaction raw materials entrance to outlet point S₁Conversion zone,S₂Conversion zone and S₃Conversion zone, S₁It is double-layer catalyst higher than the Mo-V of outer concentration that conversion zone is equipped with internal layer concentration, S₃Conversion zoneReactor is in-built has the double-decker catalyst (I) that chief component is represented by general formula (I) and (II), S₂Conversion zone is equipped with S₁SectionWith S₃The mixed catalyst of section two-stage catalytic agent.

3. method according to claim 2, is characterized in that S₁Conversion zone length is less than 1/3 of total reactor length, S₂InsteadAnswer segment length to be less than 1/3 of total reactor length, S₃Conversion zone length is less than 1/2 of total reactor length.

4. method according to claim 2, is characterized in that S₂The volume ratio of conversion zone mixed catalyst meets followingPart,Wherein internal layer concentration is double-layer catalyst volume V lower than the Mo-V of outer concentration₂, internal layer concentration higher than outsideThe Mo-V of layer concentration is double-layer catalyst volume V₁。

5. method according to claim 1, is characterized in that reactor is along reaction raw materials entrance to outlet point S₁Conversion zone andS₂Conversion zone.

6. method according to claim 5, is characterized in that along feed(raw material)inlet end to port of export beds entrancePlace to 1/3 place or porch double-deck higher than the Mo-V system of outer concentration to the described internal layer concentration of the scope filling between 1/2 placeThe catalyst of catalyst (I '), residue conversion zone filling chief component is by the catalyst (I) of general formula (I) and (II) expression.

7. according to the method described in claim 1～6 any one, it is characterized in that the process conditions of oxidation reaction are: react formerMaterial methacrylaldehyde, water, oxygen more than 180 DEG C enter reactor after preheating through preheater, salt bath heating, salt temperature 240～260DEG C, air speed 800～2000h^-1, feed composition: methacrylaldehyde 8～12 volume %, steam 11～17%, oxygen 9～17 volume %,Nitrogen 58～71 volume %.

8. method according to claim 7, is characterized in that 240～250 DEG C of salt temperatures; Air speed 800～1800h^-1。

9. method according to claim 1, is characterized in that the outer each constituent content of used catalyst should than internal layer parentConstituent content is high by 0.1～18%.

10. method according to claim 1, is characterized in that in used catalyst (I), B is lanthanum, and catalyst outer layer is mainComposition is represented by general formula (II): Mo_a′V_b′W_c′Cu_d′Ni_fSb_gA_hLa_iO_x(ⅱ)。

11. methods according to claim 10, is characterized in that in used catalyst (I), lanthanum source is lanthanum nitrate.

12. according to the method described in claim 1,9,10,11 any one, it is characterized in that the preparation side of used catalyst (I)Method comprises the steps: 1) compound that contains Mo, V, W, Cu is dissolved and mixed, carry out forming internal layer mother after co-precipitationSomaplasm liquid, then add one or more of silica or silicon carbide species, drying, moulding, roasting obtains catalyst inner layer motherBody; 2) prepare outer layer catalyst according to the method for Kaolinite Preparation of Catalyst internal layer parent, in outer layer catalyst preparation process, add dioxyOne or more of SiClx or silicon carbide species, make in outer layer catalyst each concentration of element higher than the concentration of this element of internal layer;3) outer layer catalyst of preparation is coated on catalyst inner layer parent successively, after roasting, obtains finished catalyst.

13. methods according to claim 12, after is characterized in that the moulding of used catalyst internal layer parent and outer paintingAfter covering at 400～580 DEG C roasting 3～10h.