CN103772181B - A kind of unsaturated aldehyde process for selective oxidation - Google Patents

Abstract

The present invention relates to a kind of method that unsaturated aldehyde prepares unsaturated acid, adopt fixed-bed reactor, reactor is along reaction raw materials entrance to outlet point S ₁section and S ₂section, S ₁section is equipped with the Mo-Vi system double-layer catalyst of internal layer concentration higher than outer concentration, S ₂reactor is in-built has bilayer structure catalyzer (I) for section, and this catalyzer (I) has bilayer structure, and the main composition of catalyzer is represented by general formula (I) below: Mo _av _bw _ccu _dni _esn _fsi _gm _ho _x(I), the method is applicable to acrolein selectivity oxidation and prepares vinylformic acid, reactor batch temperature distribution rationally, object selectivity of product and yield high.

Description

A kind of unsaturated aldehyde process for selective oxidation

Technical field

The present invention relates to a kind of method of unsaturated aldehyde selective oxidation, be applicable to propenal or Methylacrylaldehyde selective oxidation produces corresponding unsaturated acid, be especially suitable for catalyzing propone aldehyde selective oxidation vinylformic acid.

Background technology

Current industrial main employing propylene two-step oxidation style prepares vinylformic acid, and first propylene catalytic gas phase oxidation generates propenal, and propenal is reoxidised into vinylformic acid.Acrolein oxidation reaction is strong exothermal reaction, focus can be produced in beds, the heat gathered instantaneously is constantly accumulated, to the loss of catalyst activity component be caused, come off, to such an extent as to catalyst activity reduction, the lost of life, and cause the formation aggravating by product because of over oxidation reaction, even cause uncontrolled reaction, make sintering of catalyst.

The appearance of " progress of oxidative synthesis acrylic acid process and catalyzer " (petrochemical complex, the 39th volume the 7th phase in 2010) social focus also can make catalyst damage evil, shortens the work-ing life of catalyzer.For 80,000 tons/year of acroleic acid devices, propylene oxidation is prepared in acrolein reaction device needs more than 2.5 ten thousand tubulation, and acrolein oxidation is prepared in vinylformic acid reactor also needs more than 2.5 ten thousand tubulation, loads propenal, acrylic acid catalyst more than 100 ton altogether.More than 50000 reaction tubes, the filling of catalyzer ensures that not filling sky has certain difficulty, if because focus is crossed high catalyst and sintered very soon, again change agent more in a short time, it is huge for can envisioning its financial loss; In addition, carry out under cryogenic as much as possible for propenal, acrylic acid production, because reaction needed salt bath heating, it maintains the energy consumption of producing also is huge spending; Due to the generation of focus, require high temperature resistant to reaction tubes tubing, for up to ten thousand reaction tubess, tubing expense is exactly the very large cost of item.Therefore, if effectively suppress the generation of beds focus, huge economic benefit can be brought to large-scale commercial production.

Industrial propenal or methacrolein oxidation prepare the reaction unit mainly many reaction tubess of corresponding unsaturated aldehyde, ensureing that catalyzer is not sintered, under the prerequisite of long service life, improve selectivity and object product yield as far as possible, conservation, even if if feed stock conversion, vinylformic acid yield improve 0.1 ~ 0.5 percentage point, the amount of the product obtained increases with the level of hundreds of ~ thousands of tons of, and its economic benefit is also very considerable.

At present, there is multiple method can reduce or avoid gathering and peroxidation of focus, can from the viewpoint of the improvement two of the improvement of reaction unit and catalyzer.In catalyzer, as: Japanese Patent Laid-Open 04-217932 propose a kind of suppress focus appearance or focus on the method for hot polymerization collection, namely by the multiple catalyzer with different possessive volume of preparation, and from the mode that unstripped gas inlet side reduces to outlet side catalyzer possessive volume, fill reaction tubes successively, but the possessive volume of catalyzer is by the restriction of reaction tube diameter, and it is also very difficult multiple catalysts to be filled into reaction tubes.US200421442A is mixed into heat resistanceheat resistant point in the catalyst and forms catalyzer and inert substance with by catalyst dilution, and the method for tubulose made by catalyzer by Japanese Patent Publication 36739/1987.Further, the catalyst loading that unstripped gas ingress reduces by active ingredient.CN01121191.1 provides one to prepare acrylic acid, and namely by the gas of tube-shell type fixed bed reactor catalytic gas phase oxidation containing propenal, the method effectively inhibits the generation of focus and prepared vinylformic acid with high yield.The feature of described method is each reaction tubes to be axially divided at least three conversion zones along it, with packed catalyst first conversion zone near gas inlet higher than the catalyst activity of filling adjacent second conversion zone, and with the packed catalyst conversion zone subsequently of different activities level, catalyst activity is raised continuously to pneumatic outlet side from the second conversion zone.This catalyst reaction temperatures is higher, and substantially more than 240 DEG C, hot(test)-spot temperature is more than 300 DEG C.CN200510007929.8 provides the acrylic acid catalyzer of a kind of catalyzing propone aldehyde gaseous oxidation system, described catalyzer comprises molybdenum and vanadium, also comprise at least one volatile catalyst toxic component, its amount is 10 to 100ppb quality through ion chromatography measurement, this catalyzer can reduce the temperature of hot spot, and the reduction of the reaction efficiency of suppression thermal destruction.Specific practice is, comprise by making the volatility toxic component of specified quantitative and originally had in highly active catalyzer, catalytic activity declines momently, can reduce the temperature of hot spot.CN97104224.1 is loaded in after on carrier by catalytic active component being divided, and calcine the catalyzer of load sharing to suppress the generation of focus, the median size of catalyzer is 4 ~ 16mm, and the median size of carrier is 3 ~ 12mm, and calcining temperature is 500 ~ 600 DEG C.US2009415167A discloses a kind of method of producing unsaturated aldehyde and unsaturated acid, two or more catalyst layer is loaded in reactor, each catalyst layer by different holes density and or aperture size the shaping packed catalyst of catalytic active component, particular table area from reactor inlet to outlet catalytic active component increase gradually with control punch density and or aperture size, and then inhibited reaction focus.Even if under CN200410007263.1 provides a kind of condition forming focus, activity, selectivity, life-span are all excellent, demonstrate the catalyzer of stability for a long time, and use the method for producing acrylic acid of this catalyzer.Said catalyzer is following general formula (1) Mo _av _bw _ccu _da _eb _fc _go _xrepresent.A is at least one selected from cobalt, nickel, iron, lead, bismuth, and B is at least one selected from antimony, niobium, tin, and C is at least one selected from silicon, aluminium, titanium, zirconium.This catalyzer can not effectively suppress being emerged of beds focus.Under higher hot-spot conditions, reaction unit requires to have superpower resistance to elevated temperatures, and reaction later separation, to absorb process operations expense also very high.CN200410048021.7 discloses a kind of O composite metallic oxide catalyst, and catalyzer is by 1. molybdenum, vanadium, copper main active component and 2. requisite at least by stable component and the 3. composite oxides that form of nickel, iron, silicon, aluminium, basic metal, alkaline-earth metal of antimony and titanium.2. and be 3. wherein can composite oxides that within the scope of 120 DEG C to 900 DEG C prepared by roasting.This catalyzer shows the permanent stability under high reactivity and good selectivity.CN201010180103.2 discloses a kind of multilayer composite metal oxide catalyst, and the composition of this O composite metallic oxide catalyst can by formula M o _abi _bni _ccs _dcu _eti _fa _gb _hc _io _jrepresent, described O composite metallic oxide catalyst has multilayered structure, reduces successively from internal layer parent to each concentration of element of skin, even if catalyzer initial reaction activity is very high, this catalyzer effectively can reduce single tube reactor localized heat and gather, and suppresses being emerged of focus.This catalyzer mainly controls the focus produced because catalyzer initial activity is high, but selectivity and the yield of object product have much room for improvement, and under the mixed airflow such as propylene, water vapour long period 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, this catalyzer contains Multimetal oxide as active ingredient, this catalyzer is applicable to propylene or corresponding unsaturated aldehyde is produced in selective isobutene oxidation, the organism due to unstripped gas middle and high concentration effectively can be suppressed to contact with the catalyzer initial stage form higher focus and generate a large amount of by products, improve catalyst selectivity.These three layers of catalyzer are easy to come off through long-term operation skin, increase catalyst bed layer resistance, thus cause activity decrease.And the selectivity of this catalyzer object product and yield also have much room for improvement.

All there is a problem in the method that above-mentioned suppression focus produces, the catalyzer be filled in reaction tubes is diluted from the inlet to the outlet all in a variety of manners, both after having made catalyst runs some cycles, activity decrease also can not change thinning ratio, catalyzer also cannot reoffer higher activity, not only load, dismantle, be separated, reclaim catalyzer and make troubles, and the reactive behavior of catalyzer can be reduced, especially industrial long-term operation catalyst activity reduction is faster, affects catalyst life.

CN200980112659.3 discloses a kind of coated catalysts comprising following component: (a) carrier, b () comprises molybdenum oxide or forms the first layer of precursor compound of molybdenum oxide, (c) comprises the second layer of the poly-metal deoxide containing molybdenum and other metal of at least one.The molybdenum oxide of preferred the first layer is MoO ₃, the poly-metal deoxide of the second layer is the poly-metal deoxide that general formula I I represents: Mo ₁₂bi _acr _bx ¹ _cfe _dx ² _ex ³ _fo _y.This catalyzer is the application type catalyzer comprising carrier.Goal of the invention suppresses heterogeneously catalysed partial gas phase oxidation propenal to be acrylic acid coated catalysts inactivation, has the inactivation performance of improvement.This invention is not clearly recorded catalyzer and is used for catalyzing propone oxidation acrolein, acrylic acid reactivity worth evaluating data, such as transformation efficiency, selectivity, yield etc.CN1121441 discloses a kind of for by propenal or carry out oxidizing reaction containing the gas of acrolein gas and a kind of molecule-containing keto in vapour phase and produce acrylic acid catalyzer, this catalyzer comprises (A) a kind of composite oxides, there is molybdenum and vanadium as base stock, and be suitable for by vapor phase catalytic oxidation propenal to produce vinylformic acid, (B) solid peracid, its strength of acid (Ho) is not more than-11.93 (Ho≤-11.93).This invention adopts molybdenum vanadium type composite oxides to combine with the solid acid that a kind of strength of acid is no more than-11.93, improves the low temperature high activity of catalyzer.CN200610073671.6 discloses a kind of carrier of gas-phase oxidation catalyst, and described carrier comprises its strength of acid (H ₀) meet inequality :-5.6≤H ₀the solid acid of≤1.5; A kind of gas-phase oxidation catalyst, it comprises carrier above and comprises molybdenum and the vanadium composite oxides as basal component, and described composite oxides are carried on described carrier; Vinylformic acid is prepared by the catalytic gas phase oxidation of propenal and molecular oxygen.Prepare a method for carrier above, described method comprises the strength of acid (H by regulating the calcining temperature in the preparation being contained in the solid acid in carrier to control solid acid ₀), to meet inequality :-5.6≤H ₀≤ 1.5.CN200510059468.9 discloses a kind of vinylformic acid catalyst for producing, it is characterized in that, the oxide compound of the metallic element composition represented at following formula M oaVbWcCudOx (1) and/or composite oxides are must in the vinylformic acid catalyst for producing of catalyst component, need to control the face side that tungsten is this catalyzer partially, and/or copper is the core side of this catalyzer partially, to improve catalyst activity.Tungsten is the face side of this catalyzer partially, and/or copper is that the core side of this catalyzer is difficult to accurately control partially.

In addition, under the high temperature conditions, in catalyzer, part active ingredient molybdenum loses from catalyst surface because of distillation.The mixed airflows such as propenal, air (oxygen), nitrogen and water vapour wash away the loss of active component that also can make in catalyzer.For suppressing the loss of molybdenum distillation to cause active decay, CN1121504, by mixing copper component and having the zirconium of specified particle diameter and specific surface area and/or titanium and/or cerium, can suppress dissipation effect and the over reduction of molybdenum composition; CN1445020 adds the effect that a small amount of tellurium plays stable free molybdic oxide and copper molybdate crystalline structure, and sublimation and the over reduction of molybdenum suppress to some extent; CN1583261 is with molybdenum, vanadium, copper, tungsten and/or niobium for main ingredient, and the composite oxides formed with other element or its hopcalite form the loss that catalyzer suppresses molybdenum.

CN1328988 provides one to prepare acrylic acid, and namely by the gas of tube-shell type fixed bed reactor catalytic gas phase oxidation containing propenal, the method effectively inhibits the generation of focus and prepared vinylformic acid with high yield.The feature of described method is each reaction tubes to be axially divided at least three conversion zones along it, with packed catalyst first conversion zone near gas inlet higher than the catalyst activity of filling adjacent second conversion zone, and with the packed catalyst conversion zone subsequently of different activities level, catalyst activity is raised continuously to pneumatic outlet side from the second conversion zone.This invention needs preparation to have multiple catalyzer of different catalytically active level, and by the packed catalyst second of in lowest activity level conversion zone.With the conversion zone of packed catalyst then the second conversion zone, activity level is made to increase continuously from the second conversion zone.This invention " activity " refers to the performance that catalyzer transforms propenal.Therefore the catalyzer showing the conversion of higher (or lower) propenal is called the catalyzer with higher (or lower) activity.This invention is prepared the multiple method with the catalyzer of different activities level and is comprised: (1) regulates kind and/or the quantity of catalytic active component, (2) what regulate catalyzer occupies volume, (3) when adopting loaded catalyst, regulate the charge capacity of catalytic active component, (4) regulate the maturing temperature during catalyst preparing.

CN1343192 relates to one and propenal gas phase catalyst is oxidized to acrylic acid, wherein initial action gaseous mixture is catalyst fixed bed by one, wherein load >=150l (the s.t.p.)/lh of propenal in initial action gaseous mixture, catalyst fixed bed setting is in two spatially in reaction zone A, B in succession, and the temperature of reaction zone B is higher than the temperature of reaction zone A.Wherein the temperature of reaction zone A is 230-270 DEG C, and the temperature of reaction zone B is 250-300 ° of C, at least exceeds 5 DEG C than the temperature of reaction zone A simultaneously.This invention meets the requirement of load mainly through the temperature controlling reaction zone A, B.

CN101754944A discloses a kind of method for producing acrylic acid, utilize the first fixed-bed reactor will generate containing the gas of propenal containing the gas catalysis gaseous oxidation of propylene comprising, then utilizing the second fixed-bed reactor that obtained reaction is generated gas catalysis gaseous oxidation prepares in acrylic acid two-stage catalytic vapor-phase oxidation method, at the cooling end of the pneumatic outlet side in the air flow line downstream side and/or the first fixed-bed reactor that are arranged at the catalyst layer in the first fixed-bed reactor, be 45 ~ 99% configure the weighting material formed by solid inert material with voidage, the catalyzer for propylene to be converted into propenal by catalytic vapor phase oxidation is filled with in wherein said first fixed-bed reactor, be filled with for propenal is converted into acrylic acid catalyzer by catalytic vapor phase oxidation in described second fixed-bed reactor.Heterogeneously catalysed partial gas phase oxidation of propylene is formed acrylic acid by the open one of CN101384538.According to described method, initial action mixture comprises cyclopropane as impurity, and vinylformic acid by separating by Crystallization Separation mode after be converted to condensation mutually from product gas mixture.The open one of CN1328988 prepares acrylic acid, and namely by the gas of tube-shell type fixed bed reactor catalytic gas phase oxidation containing propenal, the method effectively inhibits the generation of focus and prepared vinylformic acid with high yield.The feature of described method is each reaction tubes to be axially divided at least three conversion zones along it, with packed catalyst first conversion zone near gas inlet higher than the catalyst activity of filling adjacent second conversion zone, and with the packed catalyst conversion zone subsequently of different activities level, catalyst activity is raised continuously to pneumatic outlet side from the second conversion zone.

The invention provides a kind of acrolein selectivity oxidation acrylic acid processed, react under low temperature, high-load condition, and improve selectivity and the yield of object product as far as possible, to obtain larger economic benefit.

Summary of the invention

The object of this invention is to provide a kind of method of unsaturated aldehyde selective oxidation, especially propenal or Methylacrylaldehyde selective oxidation produce the method for corresponding unsaturated acid.Vinylformic acid is prepared in the oxidation of particularly suitable acrolein selectivity.

A method for unsaturated aldehyde selective oxidation, adopts fixed-bed reactor, and reactor is along reaction raw materials entrance to outlet point S ₁section and S ₂section, S ₁section is equipped with the Mo-V system double-layer catalyst (as CN201110265250.4 catalyzer) of internal layer concentration higher than outer concentration, S ₂reactor is in-built has bilayer structure catalyzer (I) for section, and the main composition of this catalyzer is represented by logical formula I below.

Mo _aV _bW _cCu _dNi _eSn _fSi _gM _hO _x（Ⅰ）

Wherein: Mo is molybdenum, V is alum, and W is tungsten, and Cu is copper, and Ni is nickel, and Sn is tin, and Si is silicon, and silicon is the carrier added, and M is at least one element be selected from caesium, lanthanum, manganese; O is oxygen; A, b, c, d, e, f, g, h represent each Elements Atom ratio respectively, and wherein a=12, b are numbers of 2 ~ 8, preferably 3 ~ 6; C is a number of 0.5 ~ 7, preferably 1.0 ~ 4; D is a number of 1 ~ 6, preferably 1.0 ~ 4; E is a number of 0.5 ~ 4, and f is a number of 0.1 ~ 2, and g is a number of 0.5 ~ 50, preferably 1 ~ 20, h be 0.05 ~ 2 a number, x is the numerical value determined by the oxygen of each oxide compound.

Acrylic acid is prepared in a kind of acrolein selectivity oxidation, the processing condition of oxidizing reaction are not limited especially, as following processing condition can be adopted: reaction raw materials propenal, water, air or oxygen enter reactor after preheater more than 180 DEG C preheatings, salt bath heating, salt temperature 240 ~ 260 DEG C, preferably 240 ~ 250 DEG C; Air speed 800 ~ 2000h ^-1, preferably 800 ~ 1800h ^-1, feed composition: propenal 8 ~ 12 volume %, water vapour 11 ~ 17%, oxygen 9 ~ 17 volume %, nitrogen 58 ~ 71 volume %; The present invention sentences the catalyzer of interior scope filling CN201110265250.4 along feed(raw material)inlet end to exit end beds ingress to 1/3 place or ingress to 1/2, and (the filling scope of catalyzer is not strictly limited, 1/3 of catalyst bed length can be less than, also can unnecessary 1/3), the filling of residual catalyst bed mainly forms by Mo _av _bw _ccu _dni _esn _fsi _gm _ho _xthe catalyzer of the present invention (I) represented.Used catalyst active ingredient of the present invention not easily runs off, and water repelling property is good, effectively improves object selectivity of product and yield.

The present invention's catalyzer used is interior outer double-layer structure, every layer of catalyzer mainly forms identical, one or more volumetric molar concentration in silicon-dioxide, aluminum oxide or silicon carbide is different, one or more molar concentration rate internal layer parent in outer silicon-dioxide, aluminum oxide or silicon carbide low, there is gradient difference from inside to exterior active combination of components substrate concentration in catalyzer, is achieved concentration difference mainly through adding the materials such as different amount silicon-dioxide, aluminum oxide, silicon carbide at ectonexine.In molar content, outer each constituent content is higher by 0.1 ~ 30% than this constituent content of internal layer parent, and preferably 0.1 ~ 15%.

Used catalyst of the present invention leads to the preferred lanthanum of M in formula I, and lanthanum and nickel, copper, tin etc. can form stable crystal phase structure, as Cu ₂la, LaNi ₅, La ₂ni ₇, LaSn etc., thus suppress part active ingredient molybdenum to lose from catalyst surface because of distillation, active ingredient molybdenum not easily runs off, and delays active deterioration rate, catalyst activity and good stability.Lanthanum and molybdenum, vanadium ratio are suitable, and in logical formula I, h is a number of 0.05 ~ 2.The preferred lanthanum nitrate in lanthanum source of the present invention, the preferred sodium stannate of Xi Yuan, tin protochloride.

Used catalyst of the present invention has bilayer structure, and internal layer also can be called internal layer parent.

Used catalyst of the present invention adopts common preparation method, prepares as adopted following step.

1) Kaolinite Preparation of Catalyst internal layer parent:

Each elementary composition compound that M part in compound containing Mo, V, W, Cu, Ni, Sn and logical formula I relates to is dissolved in proportion and mixes, internal layer parent slurries are formed after carrying out co-precipitation, add in silicon-dioxide, aluminum oxide or silicon carbide in slurry production process one or more, dry, shaping, roasting obtains catalyst inner layer parent;

2) outer layer catalyst is prepared according to the method for Kaolinite Preparation of Catalyst internal layer parent, control one or more the add-on in silicon-dioxide, aluminum oxide or silicon carbide in outer preparation process, make each concentration of element in outer layer catalyst higher than the concentration of this element of adjacent inner layer;

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 after shaping and skin all need roasting 3 ~ 10h at 350 ~ 500 DEG C after application, compare not the catalyzer of respectively roasting, repeatedly roasting can improve activity and the stability of catalyzer.Can be open roasting also can be enclosed roasting, calcination atmosphere can be the rare gas elementes such as helium, nitrogen, argon gas.Catalyst layer too thick roasting time easily chap, in order to avoid be full of cracks preferably 55 ~ 125 DEG C of oven dry after application, and then roasting.The outer layer catalyst thickness being coated on internal layer parent is 0.1 ~ 2.0mm, preferably 0.2 ~ 1.5mm.

The compound of each component of used catalyst of the present invention can use the nitrate, ammonium salt, vitriol, oxide compound, oxyhydroxide, muriate, acetate etc. of each element.As ammonium molybdate, ammonium meta-vanadate, ammonium paratungstate, molybdenum oxide, cupric nitrate, cupric oxide, neutralized verdigris, nickelous nitrate, lanthanum nitrate, cesium nitrate, potassium manganate, manganese oxide etc.

After used catalyst internal layer parent slurries of the present invention are dried, the forming methods such as extrusion moulding, granulating and forming, compression molding are usually preferably adopted to be processed into spherical, hollow spheres, ellipticity, cylindric, hollow circuit cylinder etc., preferably hollow circuit cylinder or spherical.

Used catalyst of the present invention preferably uses binding agent when applying, and ectonexine catalyzer is bondd more firm.Under internal layer parent is in rolling condition, sprays binding agent infiltrates surface, then spray the outer layer catalyst powder prepared, also internal layer parent can be put into the outer layer catalyst slurries prepared and carry out rolling coating.Binding agent is selected from one or more in water, alcohols or ethers.Alcohols is as ethanol, propyl alcohol, butanols; Ethers is as ether and butyl ether.

Each layer surface preferably uneven, surface irregularity of used catalyst of the present invention, is conducive to coating, bonds more firm between ectonexine.

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

Used catalyst of the present invention can directly use, and also can be carried on inert support and use.Involved inert support can be the mixture of one or more of aluminum oxide, silicon-dioxide, silicon carbide etc.

Because catalyzer initial reaction activity is very high, so be easy to produce focus or produce heat built-up on fixed bed single tube reactor bed, catalyzer is easy to sintering, and this is very serious concerning loss suitability for industrialized production propenal vinylformic acid.Pass into a certain amount of water vapour in raw material, because specific heat of water is large, a large amount of reaction heat can be taken away, but water vapour input greatly often makes catalyst member active ingredient solution-off and makes activity decrease.Therefore catalyzer is needed to have good water repelling property.The present invention preferably uses two kinds to have double-deck multi-metal-oxide catalyst, at propenal Way in, scope before beds between 1/3 place or front 1/2 place uses internal layer concentration higher than the catalyzer (as CN201110265250.4 catalyzer) of outer concentration, the filling scope of catalyzer is not strictly limited, 1/3 of beds can be less than, also can unnecessary 1/3.Because the active component concentration of catalyst external surface is low, so corresponding activity is also low, therefore effectively can suppress being emerged of focus and gathering of heat, reduce the growing amount of by product (as hydrocarbon), improve the selectivity of object product.Use internal layer concentration lower than the catalyzer of outer concentration at residual catalyst bed, acrolein concentrations opposite inlet is lower, and catalyst activity is high, is more conducive to improving acrylic acid selectivity and yield.And catalyst agent Stability Analysis of Structures, active ingredient not easily runs off.Like this, under high-speed reaction conditions, two kinds have double-deck catalyzer layering filling, reaction bed temperature distribution is more reasonable, the reaction bed temperature close to exit end is avoided to decline fast (bed temperature declines affects selectivity of catalyst and yield, is unfavorable for the steady running of catalyzer long period).Catalyzer has good water repelling property, improves selectivity and the yield of object product.

Acrolein selectivity oxidation of the present invention acrylic acid processed, catalyst segments is loaded, and feed(raw material)inlet section is equipped with the Mo-V system double-layer catalyst of internal layer concentration higher than outer concentration, suppresses focus; Remainder bed filling internal layer concentration, lower than the Mo-V system double-layer catalyst of outer concentration, is avoided the decline of the reaction bed temperature close to exit end, is conducive to improving object product yield and highly selective, long period stably can produces vinylformic acid.

Embodiment

Illustrate that acrylic acid is prepared in acrolein selectivity oxidation with specific embodiment below, and but scope of the present invention is not limited to these embodiments.The analytical procedure of product composition adopts this area universal method.

Embodiment 1:

The preparation of catalyzer 1

Step 1: Kaolinite Preparation of Catalyst internal layer parent

(1) preparation of active ingredient slurries (a)

Under agitation, get 211.9 grams of ammonium molybdates, ammonium meta-vanadate 46.8 grams, be dissolved in (water temperature more than 65 DEG C) in 500ml pure water, obtain slurries (1), then get 52.2 grams of ammonium paratungstates, 127.9 grams of cupric nitrates, 14.5 grams of nickelous nitrates, 48 grams of sodium stannates, 5.8 grams of cesium nitrates are dissolved in (water temperature more than 65 DEG C) in 1000ml pure water, fully be uniformly mixed, obtain slurries (2).Then, slurries (1) mix with slurries (2), obtain slurries (3), obtain active ingredient slurries (a).

(2) preparation of catalyst inner layer parent

90 grams of silicon-dioxide and 1.4 grams of graphite are added in active ingredient slurries (a), 80 DEG C of strong stirrings carry out the drying of coprecipitation reaction post-heating, with 160 DEG C of thermal treatments 3 hours in nitrogen, then be the hollow columnar particle of φ 4.5 × 5mm through banded extruder extrusion molding, dry rear 460 DEG C of roastings 5 hours for 110 DEG C, obtained catalyst Precursors, this catalyst inner layer parent mainly consists of: Mo ₁₂v ₄w ₂cu _5.5ni _0.5sn _1.8cs _0.3si ₁₅o _x.

Step 2: Kaolinite Preparation of Catalyst is outer

(1) preparation of active ingredient slurries (a)

Identical with the preparation of active ingredient slurries (a) in embodiment 1 catalyst inner layer parent.

(2) preparation of catalyst outer layer

Active ingredient slurries (a) and 10.8 grams of silicon dioxide powders are carried out coprecipitation reaction post-heating dry, with 150 DEG C of thermal treatments 3 hours in nitrogen, then 530 DEG C of roastings 4.5 hours, process to obtain catalyst outer layer powder through pulverizing, grinding, sieve, and outer group mainly becomes: Mo ₁₂v ₄w ₂cu _5.5ni _0.5sn _1.8cs _0.3si _1.8o _x, outer field constituent content is higher by 0.4% ~ 14% than this constituent content of internal layer.

Step 3: Kaolinite Preparation of Catalyst 1

Catalyst inner layer parent step 1 prepared is placed in round bottom container, ethanolic soln is sprayed to catalyst Precursors under container rotation condition, stop operating under the condition of fully wetting catalyst inner layer parent, put it into rapidly another rotate be placed with in the round bottom container of outer layer catalyst powder of step 2 gained, apply, coat-thickness is at 0.5 ~ 1.5mm, and namely gained catalyzer 105 DEG C obtains catalyzer 1 in 4.5 hours through 450 DEG C of roastings after drying.

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermopair, loads 10mlCN201110265250.4 catalyzer 3(S along feedstock direction reactor bed ₁section), the above-mentioned catalyzer 1 of 20ml or comparative catalyst 1 or 2(S ₂section), salt bath heating, salt temperature 242 DEG C.From above-mentioned reaction tubes ingress with air speed 900h ^-1enter the mixed gas of propenal 8 volume %, oxygen 13 volume %, water vapour 16 volume %, nitrogen 63 volume %.24 hours beds S are reacted under the low temperature of 242 DEG C ₂section hot localised points temperature 271 DEG C, acrolein conversion rate is 98.8%, acrylic acid selectivity 90.5%, vinylformic acid yield 89.0%.Adopt two kinds of double-layer catalyst segmentation fillings, compare a kind of catalyst agent bed S of filling separately ₂section hot localised points temperature increases, and reaction bed temperature calibration is more reasonable, improves object selectivity of product and yield.Comparative example 1,2 selectivity relative mistake, vinylformic acid yield is low.After the oxidizing reaction 1000h of embodiment 1, bed S ₂section hot localised points temperature is 270 DEG C ~ 271 DEG C, and acrolein conversion rate is 99.0%, acrylic acid selectivity 90.4%, vinylformic acid yield 89.0%.Catalyst activity component molybdenum etc. not easily runs off, and stable performance, has good water repelling property, and acrolein selectivity oxidizing reaction long period is stably carried out.

Comparative example 1:

Independent loading catalyst 1, acrolein selectivity oxidizing reaction is with embodiment 1.React 24 hours S ₂section hot localised points temperature 275 DEG C, acrolein conversion rate is 98.9%, acrylic acid selectivity 88.3%, vinylformic acid yield 86.5%.

Comparative example 2:

With the skin of catalyzer 1 for comparative catalyst 2, banded extruder extrusion molding is the hollow columnar particle of φ 4.5 × 5mm, and acrolein selectivity oxidizing reaction is with embodiment 1.React 24 hours S ₂section hot localised points temperature 273 DEG C, acrolein conversion rate is 98.8%, acrylic acid selectivity 88.0%, vinylformic acid yield 86.1%.

Embodiment 2:

The preparation of catalyzer 2

With the preparation process of embodiment 1 catalyzer 1 and main raw material identical, just add 16.2 grams of lanthanum nitrates, internal layer adds 162 grams of silicon-dioxide and 2.3 grams of silicon carbide, and through banded extruder extruding, rolling is a granulated into the ball shape that diameter is 2mm, and outer 13.2 add a gram silicon-dioxide.Coat-thickness, at 0.5 ~ 2.0mm, namely obtains catalyzer 2 in 3 hours through 450 DEG C of roastings.Catalyzer 2 internal layer parent mainly consists of: Mo ₁₂v ₅w ₄cu ₂ni _3.7sn _0.6la _0.5si _25.2o _x, skin mainly consists of: Mo ₁₂v ₅w ₄cu ₂ni _3.7sn _0.6la _0.5si _2.2o _x, outer field constituent content is higher by 0.8% ~ 17.4% than this constituent content of internal layer.

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermopair, loads 12mlCN201110265250.4 catalyzer 1(S along feedstock direction reactor bed ₁section), the above-mentioned catalyzer of 18ml or comparative example catalyzer (S ₂section), salt bath heating, salt temperature 245 DEG C.From above-mentioned reaction tubes ingress with air speed 1200h ^-1enter the mixed gas of propenal 8 volume %, oxygen 12 volume %, water vapour 14 volume %, nitrogen 66 volume %.React 24 hours, beds S ₂section hot localised points temperature 277 DEG C, acrolein conversion rate is 99.2%, acrylic acid selectivity 91.6%, vinylformic acid yield 89.8%.Adopt two kinds of double-layer catalyst segmentation fillings, compare a kind of catalyst agent bed S of filling separately ₂section hot localised points temperature increases, and reaction bed temperature calibration is more reasonable, improves object selectivity of product and yield.Comparative example 3,4 selectivity relative mistake, vinylformic acid yield is low.After the oxidizing reaction 1000h of embodiment 2, bed S ₂section hot localised points temperature is 276 DEG C ~ 277 DEG C, and acrolein conversion rate is 99.1%, acrylic acid selectivity 91.8%, vinylformic acid yield 89.9%.Catalyst activity component molybdenum etc. not easily runs off, and stable performance, has good water repelling property, and acrolein selectivity oxidizing reaction long period is stably carried out.

Comparative example 3:

Independent loading catalyst 2, acrolein selectivity oxidizing reaction is with embodiment 2.React 24 hours S ₂section hot localised points temperature 282 DEG C, acrolein conversion rate is 99.0%, acrylic acid selectivity 88.2%, vinylformic acid yield 86.6%.

Comparative example 4:

With the skin of catalyzer 2 for comparative catalyst 4, banded extruder extrusion molding is the hollow columnar particle of φ 5 × 5mm, and acrolein selectivity oxidizing reaction is with embodiment 2.React 24 hours S ₂section hot localised points temperature 280 DEG C, acrolein conversion rate is 99.1%, acrylic acid selectivity 87.4%, vinylformic acid yield 86.0%.

Embodiment 3:

With the preparation process of embodiment 1 catalyzer 1 and main raw material identical, just add 11.8 grams of potassium manganates, internal layer add 174.6 grams of silicon-dioxide and and 1.6 grams of aluminum oxide; Skin adds 4.2 grams of silicon-dioxide.Catalyzer 3 internal layer parent mainly consists of: Mo ₁₂v ₂w _6.7cu ₁ni _1.2sn _1.0si _20.5mn _0.6o _x, skin mainly consists of: Mo ₁₂v ₂w _6.7cu ₁ni _1.2sn _1.0si _0.7mn _0.6o _x

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermopair, loads 13mlCN201110265250.4 catalyzer 3(S along feedstock direction reactor bed ₁section), the above-mentioned catalyzer (S of 17ml ₂section), salt bath heating, salt temperature 253 DEG C.From above-mentioned reaction tubes ingress with air speed 2000h ^-1enter the mixed gas of propenal 11 volume %, oxygen 15 volume %, water vapour 15 volume %, nitrogen 59 volume %.React 24 hours, beds S ₂section hot localised points temperature 283 DEG C, acrolein conversion rate is 99.2%, acrylic acid selectivity 91.0%, vinylformic acid yield 89.4%.Adopt two kinds of double-layer catalyst segmentation fillings, compare a kind of catalyst agent bed S of filling separately ₂section hot localised points temperature increases, and reaction bed temperature calibration is more reasonable, improves object selectivity of product and yield.

Embodiment 4:

With the preparation process of embodiment 2 catalyzer 2 and main raw material identical, internal layer adds 60 grams of silicon-dioxide and 4.3 grams of graphite, through banded extruder extruding, rolling is a granulated into the ball shape that diameter is 2mm, skin adds 6 grams of silicon-dioxide, coat-thickness is at 0.5 ~ 2.0mm, 370 DEG C of roastings 7 hours, catalyzer 4 internal layer parent mainly consisted of: Mo ₁₂v ₈w _0.5cu ₄ni _2.4sn _0.1si ₁₀la _1.8o _x, skin mainly consists of: Mo ₁₂v ₈w _0.5cu ₄ni _2.4sn _0.1si _1.0la _1.8o _x

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermopair, loads 15mlCN201110265250.4 catalyzer 3(S along feedstock direction reactor bed ₁section), the above-mentioned catalyzer (S of 15ml ₂section), salt bath heating, salt temperature 250 DEG C.From above-mentioned reaction tubes ingress with air speed 1600h ^-1enter the mixed gas of propenal 9 volume %, oxygen 14 volume %, water vapour 17 volume %, nitrogen 60 volume %.React 24 hours, beds S ₂section hot localised points temperature 281 DEG C, acrolein conversion rate is 99.1%, acrylic acid selectivity 91.4%, vinylformic acid yield 89.4%.Reaction bed temperature calibration is more reasonable, improves object selectivity of product and yield.After the oxidizing reaction 1000h of embodiment 4, bed S ₂section hot localised points temperature is 280 DEG C ~ 282 DEG C, and acrolein conversion rate is 99.2%, acrylic acid selectivity 91.3%, vinylformic acid yield 89.6%.Catalyst activity component molybdenum etc. not easily runs off, and stable performance, has good water repelling property, and acrolein selectivity oxidizing reaction long period is stably carried out.

Comparative example 5:

At on 09 08th, the 2011 independent filling CN201110265250.4(applying date) catalyzer 1, acrolein selectivity oxidizing reaction is with embodiment 2.React 24 hours S ₂section hot localised points temperature 269 DEG C, acrolein conversion rate is 98.5%, acrylic acid selectivity 88.3%, vinylformic acid yield 86.3%.

Claims (9)

1. a method for unsaturated aldehyde selective oxidation, described method is applied to acrolein selectivity oxidation and prepares vinylformic acid, adopts fixed-bed reactor, it is characterized in that reactor is along reaction raw materials entrance to outlet point S ₁section and S ₂section, S ₁section is equipped with the Mo-V system double-layer catalyst of internal layer concentration higher than outer concentration, and the main composition of this catalyzer is by general formula (I ') expression below: 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, and A is at least one element be selected from copper, cobalt, manganese, B is at least one element in selected among zirconium, strontium, lanthanum, magnesium and titanium, Si is silicon, and silicon is the carrier added, and O is oxygen, a, b, c, d, e, f, g represents each Elements Atom ratio respectively, wherein a=12, b is a number of 3 ~ 10, c is a number of 0.5 ~ 5, d is a number of 1 ~ 5, e is a number of 0 ~ 3, f is a number of 0 ~ 3, g is a number of 0.5 ~ 30, x is the numerical value determined by the oxygen of each oxide compound, described catalyzer (I ') has interior outer double-layer structure, every layer of catalyzer mainly forms identical, but one or more the total content in silicon-dioxide or silicon carbide is different, one or more total content in outer silicon-dioxide or silicon carbide is than the height of internal layer parent, in molar content, catalyst outer layer each constituent content concentration ratio internal layer parent is low, S ₂reactor is in-built has bilayer structure catalyzer (I) for section, and the main composition of this catalyzer is represented by logical formula I below: Mo _av _bw _ccu _dni _esn _fsi _gm _ho _x(I), wherein: silicon is the carrier added, M is at least one element be selected from caesium, lanthanum, manganese, O is oxygen, a, b, c, d, e, f, g, h represents each Elements Atom ratio respectively, wherein a=12, b is a number of 2 ~ 8, c is a number of 0.5 ~ 7, d is a number of 1 ~ 6, e is a number of 0.5 ~ 4, f is a number of 0.1 ~ 2, g is a number of 0.5 ~ 50, h is a number of 0.05 ~ 2, x is the numerical value determined by the oxygen of each oxide compound, described catalyzer (I) has interior outer double-layer structure, every layer of catalyzer mainly forms identical, ectonexine adds one or more in different amount silicon-dioxide or silicon carbide, gradient difference is there is in catalyzer from inside to exterior active combination of components substrate concentration, in molar content, outer each constituent content is higher by 0.1 ~ 30% than this constituent content of internal layer parent.

2. method according to claim 1, it is characterized in that sentencing Mo-V system double-layer catalyst (I ') of the internal layer concentration described in interior scope filling higher than outer concentration along feed(raw material)inlet end to exit end beds ingress to 1/3 place or ingress to 1/2, the filling of residual catalyst bed mainly forms by Mo _av _bw _ccu _dni _esn _fsi _gm _ho _xthe double-layer catalyst (I) represented.

3. method according to claim 2, is characterized in that the processing condition of oxidizing reaction are: reaction raw materials propenal, water, oxygen enter reactor, salt bath heating after preheater more than 180 DEG C preheatings, salt temperature 240 ~ 260 DEG C, air speed 800 ~ 2000h ^-1, feed composition: propenal 8 ~ 12 volume %, water vapour 11 ~ 17%, oxygen 9 ~ 17 volume %, nitrogen 58 ~ 71 volume %.

4. method according to claim 3, is characterized in that salt temperature 240 ~ 250 DEG C, air speed 800 ~ 1800h ^-1.

5. method according to claim 1, is characterized in that the outer each constituent content of used catalyst (I) is higher by 0.1 ~ 15% than this constituent content of internal layer parent.

6. method according to claim 1, it is characterized in that used catalyst leads to the number that b in formula I is 3 ~ 6, c is a number of 1.0 ~ 4, and d is a number of 1.0 ~ 4, and g is a number of 1 ~ 20.

7. method according to claim 1, it is characterized in that used catalyst leads to M in formula I is lanthanum, and the main composition of catalyzer is represented by (II): Mo _av _bw _ccu _dni _esn _fsi _gla _ho _x(II), wherein h is a number of 0.05 ~ 2.

8. the method according to any one of claim 1,5,6,7, it is characterized in that the preparation method of used catalyst (I) comprises the steps: 1) each elementary composition compound that M part in the compound containing Mo, V, W, Cu, Ni, Sn and logical formula I relates to is dissolved in proportion and mixes, internal layer parent slurries are formed after carrying out co-precipitation, add in silicon-dioxide or silicon carbide in slurry production process one or more, dry, shaping, roasting obtains catalyst inner layer parent; 2) prepare outer layer catalyst according to the method for Kaolinite Preparation of Catalyst internal layer parent, in outer preparation process, control one or more the add-on in silicon-dioxide or silicon carbide, make each concentration of element in outer layer catalyst higher than the concentration of this element of adjacent inner layer; 3) outer layer catalyst of preparation is coated on catalyst inner layer parent successively, after roasting, obtains finished catalyst.

9. method according to claim 8, is characterized in that used catalyst internal layer parent after shaping and skin roasting 3 ~ 10h at 350 ~ 500 DEG C after application.