CN103769146A - Propylene oxidation catalyst and preparation method thereof - Google Patents

Abstract

The invention relates to a multi-metal oxide catalyst. The multi-metal oxide catalyst has a general formula of MoaBibFecCodWeKfSigAhBiOx (I). In the general formula of MoaBibFecCodWeKfSigAhBiOx (I), silicon is used as a carrier in the catalyst, A represents at least one of titanium, manganese, boron and lanthanum, B represents at least one of alkaline-earth metals, and O represents oxygen. The multi-metal oxide catalyst is used for propylene selective-oxidation reaction and has the characteristics of high reaction activity, high selectivity and long service life.

Description

Propylene oxidation catalyst and preparation method

Technical field

The present invention relates to a kind of Propylene Selectivity oxidation and produce multi-metal-oxide catalyst of methacrylaldehyde and preparation method thereof.

Background technology

Propylene gas phase catalytic oxidation reaction is prepared methacrylaldehyde, acrylic acid is strong exothermal reaction, in reactor, moment is assembled a large amount of reaction heat, form hot localised points, if can not remove timely and effectively reaction heat, the heat that moment is gathered is constantly accumulated, by cause catalyst activity component loss, come off, to such an extent as to catalyst activity reduction, the lost of life, and cause because over oxidation reacts the formation that aggravates accessory substance, thereby reduce methacrylaldehyde and acrylic acid yield.Even cause runaway reaction, make sintering of catalyst.

The appearance of " progress of oxidation acrylic acid synthesizing process and catalyst " (petrochemical industry, the 39th the 7th phase of volume in 2010) social focus also can make catalyst damage evil, shortens the service life of catalyst.Take 80,000 tons/year of acroleic acid devices as example, propylene oxidation is prepared and in acrolein reaction device, is needed more than 25000 tubulation, acrolein oxidation to prepare in acrylic acid reactor also to need more than 25000 tubulation, load altogether more than 100 ton of methacrylaldehyde, acrylic acid catalyst.More than 50000 reaction tube, the filling of catalyst guarantees not fill empty certain difficulty that has, if because focus is crossed the very fast sintering of high catalyst, again change in a short time agent, it is huge can envisioning its economic loss again; In addition, for methacrylaldehyde, acrylic acid production, carry out as much as possible under cryogenic conditions, because reaction needed salt bath heating, its energy resource consumption that maintains production is also huge spending; Due to the generation of focus, high temperature resistant to the requirement of reaction tube tubing, for up to ten thousand reaction tubes, tubing expense is exactly a very large cost payout.Therefore,, if effectively suppress the generation of beds focus, can bring huge economic benefit to large-scale industrial production.

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

At present, there is several different methods can reduce or avoid gathering and peroxidization of focus, as: Japanese patent laid-open 04-217932 has proposed the method for the hot polymerization collection on a kind of appearance or focus that suppresses focus, by preparing the multiple catalyst with different possessive volumes, and the mode reducing to outlet one side catalyst possessive volume from unstripped gas inlet side, fill successively reaction tube, but the possessive volume of catalyst is subject to the restriction of reaction tube diameter, and it is also very difficult that multiple catalysts is filled into reaction tube.CN1210511A prepares the multiple catalyst-loaded catalyst layer that arranges in reaction tube with different activities, arranges above-mentioned several catalyst-loaded according to the entrance from unstripped gas to the active order uprising of outlet.Also there is other method, for example, inert substance and catalyst mix, reduce the activity of catalyst, be loaded into reactor inlet place, Japanese Unexamined Patent Publication 10614/1972 is sneaked into heat resistanceheat resistant point to form catalyst is inert substance with by catalyst dilution in catalyst, and Japanese Patent Publication 36739/1987 is made catalyst the method for tubulose.There is again the Catalyst packing that unstrpped gas porch reduces by active component.CN01111960.8 uses fixed bed shell and tube reactor, under catalyst exists, prepare methacrylaldehyde and acrylic acid by propylene gas phase catalytic oxidation reaction, the method is the generation of focus or the hot polymerization collection on focus in inhibitory reaction district effectively, this catalyst consist of Mo _aw _bbi _cfe _da _eb _fc _gd _he _io _x, wherein the implication of Mo, W, Bi, Fe, A, B, C, D, E and O and a, b, c, d, e, f, g, h, i and x is as described in description.The feature of the method is the multiple catalysts that preparation has above-mentioned composition, but kind and/or the quantity of the temperature that (α) possessive volume, (β) calcine and/or (γ) alkali metal are different, and press the mode of catalyst activity from unstripped gas entrance to Increasing exports, catalyst is filled into reaction zone successively.CN00122609.6 provides under the condition that has the oxide catalyst that contains Mo-Bi-Fe compound, produce methacrylaldehyde and acrylic acid by vapor phase propylene oxide, described catalyst is filled in multitubular reactor of fixed bed, and the method can generate methacrylaldehyde and acrylic acid with high stable yield in long-time.The method is characterized in that in the each tubular reactor that configures vertically two or more reaction zones that each district's filling different catalysts is filled out catalyst Bi and/or Fe content and reduced with the ratio of Mo content from gas access end to gas outlet end.CN1672790A provides a kind of catalyzing propone aldehyde gaseous oxidation system acrylic acid catalyst, described catalyst 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 catalyst can reduce the temperature of hot spot, and suppresses the reduction of the reaction efficiency of thermal degradation.Specific practice is that, by the volatility toxic component of specified quantitative being comprised and originally having in highly active catalyst, catalytic activity declines momently, can reduce the temperature of hot spot.CN1165055A is by after dividing catalytic active component and being loaded on carrier, calcines the generation that the catalyst of load sharing suppresses focus, and the average grain diameter of catalyst is 4～16mm, and the average grain diameter of carrier is 3～12mm, and calcining heat is 500～600 ℃.CN1314331A provides the catalyst of a kind of Mo-W-Bi-Fe of containing, this catalyst is by the mode that changes the kind of possessive volume calcining heat and/or alkali metal and/or quantity and increase to outlet one side from the inlet side of unstripped gas according to catalyst activity, fills successively reaction zone with described multiple types catalyst.Catalyst is at least divided into two-layer in the axial direction of reaction tube, and this catalyst is the multiple types catalyst with different activities level, can be by changing calcining heat and/or wherein kind and/or the quantity of alkali metal obtain.Hot polymerization collection on appearance or the focus of focus is effectively suppressed.JP200982239A discloses a kind of catalyst of the gas phase oxidation for the hydrocarbon such as 3C or 4C, and composition Mo (a) Bi (b) Co (c) Ni (d) Fe (e) X (f) Y ' of this catalyst is Z (h) Q (i) Si (j) O (k) or Mo (12)-V (a ') X ' (b ') Cu (c ') Y (g) " (d ') Sb (e ') Z ' (f ') Si (g ') C (h ') O (i ').X is selected from sodium, potassium, rubidium, caesium or thallium, and Y ' is selected from boron, phosphorus, arsenic or tungsten; Z is selected from magnesium, calcium, zinc, cerium; Y " is selected from magnesium, calcium, barium, zinc or strontium; Z ' chosen from Fe, cobalt, nickel, bismuth or aluminium.All there is a problem in the method that above-mentioned inhibition focus produces, the catalyst being filled in reaction tube has all been diluted with various forms from the inlet to the outlet, both after having made catalyst runs some cycles, active decline also can not change thinner ratio, catalyst also cannot provide higher activity again, not only loading, dismantle, separate, reclaim catalyst makes troubles, and can reduce the reactivity of catalyst, especially industrial long-term operation catalyst activity reduction is faster, affects catalyst life.CN101274279 discloses a kind of oxide catalyst, and it is represented by following formula (2): Mo ₁₂bi _afe _ba _cb _dc _ed _fo _x(2) (wherein Mo is molybdenum, and Bi is bismuth, and Fe is iron, and A is the element that is at least selected from cobalt and nickel, and B is the element that is at least selected from alkali metal, alkaline-earth metal and thallium, and C is the element that is at least selected from tungsten, silicon, aluminium, zirconium and titanium; D is the element that is at least selected from phosphorus, tellurium, antimony, tin, caesium, lead, niobium, manganese, arsenic and zinc, and O is oxygen; A, b, c, d, e, f and x are the corresponding atomic ratios of Bi, Fe, A, B, C, D and O, it is respectively 0 < a≤10,0 < b≤20,2≤c≤20,0 < d≤10,0≤e≤30,0≤f≤4, and x is the numerical value definite by the oxidation state of respective element).This invention is in order to solve because the appearance of catalyst focus causes it active or selectively due to sintering etc. and significantly reduced problem.This invention is such technical solution problem, the catalyst packing in reactor has specific particle size distribution, space between catalyst granules can be by even and expansion, can suppress the appearance of local extra high temperature spot (focus) in catalyst layer and not reduce methacrylaldehyde or acrylic acid output, and can obtain long-term and stably methacrylaldehyde or acrylic acid.This catalyst particle size relative standard deviation is 0.02-0.20.Because industrial methacrylaldehyde, acrylic acid production loaded catalyst are larger; want to guarantee that the particle size relative standard deviation of catalyst is 0.02-0.20; can restrict undoubtedly the large-scale production of catalyst, can be because of the irregularity of catalyst size as useless agent processing in possible production process.And tons of catalyst, the work that screening particle size relative standard deviation is 0.02-0.20 is also wasted time and energy very much.

CN201010180103.2 discloses a kind of multilayer composite metal oxide catalyst, and the composition of this O composite metallic oxide catalyst can be by formula M o _abi _bni _ccs _dcu _eti _fa _gb _hc _io _jrepresent, wherein: Mo is molybdenum, Bi is bismuth, and Ni is nickel, and Cs is caesium, and Cu is copper, and Ti is titanium, and A is at least one element being selected from arsenic, tellurium, manganese, cerium, niobium, zirconium, rubidium, cadmium and germanium; B is at least one element being selected from cobalt, boron, strontium, tantalum, alkali and alkaline earth metal ions; C is at least one element being selected from vanadium, tin, gallium, zinc, iron, tungsten and antimony; O is oxygen, described O composite metallic oxide catalyst has sandwich construction, reduces successively, even if catalyst initial reaction activity is very high from internal layer parent to the each concentration of element of skin, this catalyst can effectively reduce single tube reactor localized heat and gather, and suppresses emerging of focus.This catalyst is mainly to control due to the high focus producing of catalyst initial activity, but the selective and yield of object product has much room for improvement, and under the mixed airflow such as propylene, steam 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 catalyst contains Multimetal 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 a large amount of accessory substances because the organic matter of unstripped gas middle and high concentration contacts with the catalyst initial stage to form compared with high focus, improve catalyst selectivity.This catalyst preparation process complexity, three layers of catalyst are easy to come off through long-term operation skin, increase catalyst bed layer resistance, thereby cause active decline.And the selective and yield of this catalyst object product also has much room for improvement.

CN200980112659.3 discloses a kind of coated catalysts of comprising following component of the present invention relates to: (a) carrier, (b) ground floor of the precursor compound that comprises molybdenum oxide or formation molybdenum oxide, (c) comprises the second layer containing the poly-metal deoxide of molybdenum and at least one other metal.Preferably the molybdenum oxide of ground floor 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 catalyst is the application type catalyst that comprises carrier.Goal of the invention is that inhibition heterogeneously catalysed partial gas phase oxidation methacrylaldehyde is acrylic acid coated catalysts inactivation, has improved inactivation performance.This invention is not clearly recorded catalyst and is oxidized acrolein, acrylic acid reactivity worth evaluating data for catalyzing propone, such as conversion ratio, selective, yield etc.CN200710106391.5 discloses a kind of preparation method of composite oxide catalysts, and wherein this catalyst is the catalyst that the olefin oxidation that contains molybdenum and bismuth is used, and it is characterized in that, its specific area is at 5～25m ²/ g, its pore volume are in the scope of 0.2～0.7cc/g, and during its fine pore distributes, there is following distribution: fine pore (diameter) the shared pore volume of the pore of 0.03～0.1 μ m be in total pore volume more than 30% or 30%, the shared pore volume of the pore of 0.1～1 μ m be in total pore volume more than 20% or 20%, and pore diameter is below 10% or 10% than the little proportion of 0.03 μ m, this composite oxide catalysts is represented by following general formula (1): Mo _abi _bco _cni _dfe _ex _fy _gz _hsi _io _j(1) in formula, X is from by magnesium (Mg), calcium (Ca), zinc (Zn), cerium (Ce), at least a kind of element selecting in the group of samarium (Sm) and halogen composition, Y is from by sodium (Na), potassium (K), rubidium (Rb), at least a kind of element selecting in the group of caesium (Cs) and thallium (Tl) composition, Z is from by boron (B), phosphorus (P), at least a kind of element selecting in the group of arsenic (As) and tungsten (W) composition, in addition, a～j represents the atomic ratio of each element, a=12, b=0.5～7, c=0～10, d=0～10, wherein c+d=1～10, e=0.05～3, f=0～2, g=0.04～2, h=0～3, i=5～48, in addition, j is the numerical value that meets the state of oxidation of other element.This invention needs pyrolytic silicon dioxide, and catalyst component disperses together with silicon, controls specific surface area of catalyst, pore volume, fine pore and distributes, and improves conversion ratio and selective etc.The height of beds hot localised points temperature is not mentioned in this invention.High to ingredient requirement, complicated process of preparation, catalytic component is many, and specific area, pore volume, fine pore distribute and are difficult to effectively control, poor repeatability.JP5293389A discloses a kind of PROPENE IN GAS PHASE OXIDATION and has prepared the acrylic acid catalyst of methacrylaldehyde, and the composition of catalyst can have general formula to represent Mo _abi _bfe _ca _dx _ey _fz _gsi _go _i.A is at least one element being selected from cobalt and nickel, X is for being selected from least one element in Mg, Zn, Mn, Ca, Cr, Nb, Ag, Ba, Sn, Ta or Pb, Y is for being selected from P, B, S, Se, Te, Ce, W, Sb or Ti, and Z is selected from least one element of Li, Na, K, Rb, Cs or Ti.In catalyst, be added with organic polymer, this catalyst has loose structure (0.01～10 micron) and is easy to gas-phase reaction.CN101850259A(application number CN201010190267.3) preparation method that propylene oxidation under a kind of high-speed is prepared the catalyst of methacrylaldehyde is disclosed, this catalyst is that general formula is take Mo-Bi-Fe-Co composite metal oxide as basis; MoaBibFecCodXeYfZgOh, wherein Mo represents molybdenum, Bi represents bismuth, Fe represents iron, Co represents cobalt, X be selected from W, Sb, As, P, Ni, Sn and Pb at least one element, Y is at least one element being selected from Zn, Cr, Mn, Ru, Ag, Pd and Ru, Z is at least one element being selected from Na, K, Li, Rb, Cs, Ca, Mg, Sr and Ba; A, b, c, d, e, f and g represent the atomic ratio of each element, and, in the time of a=12, b is that 0.1～7, c is that 0.5～8, d+e is that 0.5～20, f is that 0～1, g is the numeral of 0～2, h for being determined by the oxidation state of above-mentioned each element; This catalyst obtains by coprecipitation method, and under co-precipitation, obtaining pH by the precursor compound of component used is 1.5～3.0 pulpous state liquid, after this pulpous state liquid is dry rapidly, adds the moulding of dilution thermal conducting agent, roasting and obtains catalyst; Or in above-mentioned gained pulpous state liquid, add dilution thermal conducting agent, rapidly dry after, moulding, roasting and obtain catalyst.This catalyst has selected the dilution thermal conducting agent with excellent heat conductivity performance to be incorporated in catalyst, and dilution thermal conducting agent is silica flour, has solved the rendezvous problem of focus under high-speed, makes catalyst have good selectively.This invention is mainly by adding dilution thermal conducting agent silica flour to improve the selective of catalyst in catalyst preparation process.Silica flour is more common in the preparation of methacrylaldehyde acrylic acid catalyst.

In addition, under hot conditions, in catalyst, part active component molybdenum loses because of distillation from catalyst surface.Propylene, air and steam mixed airflow wash away the part loss of active component that also can make in catalyst.For the loss that suppresses molybdenum distillation causes active decay, CN1121504, by mixing copper component and zirconium and/or titanium and/or the cerium with specified particle diameter and specific area, can suppress dissipation effect and the over reduction of molybdenum composition; The effect that CN1445020 adds a small amount of tellurium to play to stablize free molybdenum trioxide and molybdic acid copper crystal structure, sublimation and the over reduction of molybdenum suppress to some extent; CN1583261 is take molybdenum, vanadium, copper, tungsten and/or niobium as key component, and the composite oxides or its hopcalite that form with other element form the loss that catalyst suppresses molybdenum.

Therefore, need to provide Propylene Selectivity oxidation to prepare methacrylaldehyde, acrylic acid catalyst, in acrolein oxidation process, it is more reasonable that temperature of reactor distributes, object selectivity of product and yield are high, good in economic efficiency, can under low temperature, high-load condition, react.

Summary of the invention

The object of this invention is to provide a kind of Propylene Selectivity oxidation and produce methacrylaldehyde, acrylic acid multi-metal-oxide catalyst and preparation method thereof.There is gradient difference from inside to exterior active combination of components substrate concentration in catalyst granules of the present invention, the each constituent content concentration ratio of catalyst outer layer internal layer maternal concentration is high.Catalyst activity component is difficult for running off, and water repelling property is good, and the selective and yield of object product is high.

The present invention relates to a kind of multi-metal-oxide catalyst for propylene oxidation, the chief component of this catalyst is by general formula (I) expression below: Mo _abi _bfe _cco _dw _ek _fsi _ga _hb _io _x(I).

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Co is cobalt, and W is tungsten, and K is potassium, and Si is silicon, and silicon is the carrier adding in catalyst, and A is at least one element being selected from titanium, manganese, boron, lanthanum, B is at least one element being selected from alkaline-earth metal, O is oxygen, a, b, c, d, e, f, g, h, i represent respectively each element atomic ratio, and wherein a is a number of 12, and b is a number of 1.0～7, preferably 1.0～6, c is a number of 1～6, preferably 1～5, d is a number of 1～8, preferably 1～5, e is a number of 0.2～5, f is a number of 0.1～3.2, g is a number of 0.2～55, preferably 1～20, h is a number of 0.01～2, i is a number of 0～2, x is the numerical value being determined by the oxygen of each oxide, described multi-metal-oxide catalyst has interior outer double-layer structure, every layer of catalyst chief component is identical, but silica, the molar concentration difference of one or more in aluminium oxide or carborundum, outer silica, the molar concentration rate internal layer parent of one or more in aluminium oxide or carborundum low, in molar content, the each constituent content concentration ratio of catalyst outer layer internal layer parent is high.

Catalyst of the present invention is double-decker, and catalyst exists gradient difference from inside to exterior active combination of components substrate concentration, mainly by add the materials such as different amount silica, aluminium oxide, carborundum to be achieved concentration difference 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%.

The present invention can add active component lanthanum, and lanthanum and bismuth, cobalt can form stable crystal phase structure, as BiLa, BiLa ₂, Co ₃la ₂deng, the good dispersion of molybdenum, lose because of distillation from catalyst surface thereby suppress part active component molybdenum, active component molybdenum is difficult for running off, and before and after catalyst reaction, active component molybdenum content is substantially constant, delays active deterioration rate, catalyst activity and good stability.Lanthanum and molybdenum, cobalt ratio are suitable, and in general formula (I), A is lanthanum, and h is a number of 0.05～1.5, and i is a number of 0.01～1.2, and too much the membership that adds of lanthanum is competed molybdenum with bismuth and cobalt, affects catalyst activity.Catalyst chief component is as shown in general formula (II).

Mo _aBi _bFe _cCo _dW _eK _fSi _gLa _hB _iO _x（Ⅱ）

Multi-metal-oxide catalyst of the present invention adopts common preparation method, as adopted following step preparation.

1) Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, Bi, A in the compound of Fe, Co, W, K and general formula (I) _hb _ithe each elemental constituent compound relating to dissolve and mix, carry out forming internal layer parent slurries after co-precipitation, in slurries preparation process, add one or more in silica, aluminium oxide or carborundum, dry, moulding, 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 addition in silica, aluminium oxide or carborundum, make in outer layer catalyst each concentration of element 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.

Catalyst inner layer parent of the present invention after moulding and outer all need to be at 400～580 ℃ after coating roasting 3～10h, compare not the catalyst of roasting respectively, repeatedly roasting can improve activity and the stability of catalyst.Can be that open roasting can be also enclosed roasting, calcination atmosphere can be the inert gases such as helium, nitrogen, argon gas.

Catalyst layer easily chaps when thick roasting very much, for fear of be full of cracks be preferably in apply after 55～125 ℃ 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 0.2～1.5mm.

The compound of each component of catalyst of the present invention can use nitrate, ammonium salt, sulfate, oxide, hydroxide, chloride, acetate of each element etc., as lanthanum nitrate, magnesium nitrate, potassium manganate, manganese dioxide, ammonium borate, boric acid, titanium dioxide, barium nitrate etc., calcium nitrate, strontium nitrate etc.

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

When catalyst of the present invention applies, preferably use binding agent, make ectonexine catalyst bonding more firm.Under rolling condition, spray binding agent at internal layer parent and infiltrate surface, then the outer layer catalyst powder for preparing of spraying, also internal layer parent can be put into the outer layer catalyst slurries that the prepare coating of rolling.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.

Preferably uneven, the rough surface of each layer of surface of catalyst of the present invention, is conducive to apply, and bonding is more firm between layers.

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

The present invention has double-decker, and internal layer also can be called internal layer parent.Object product mainly refers to methacrylaldehyde, acrylic acid.

Because catalyst initial reaction activity is very high, so be easy to produce focus or produce heat localization on fixed bed single tube reactor bed, catalyst is easy to sintering, and this loses concerning suitability for industrialized production methacrylaldehyde acrylic acid is very serious.In raw material, pass into a certain amount of steam, because specific heat of water is large, can take away a large amount of reaction heat, make active decline but steam input greatly often makes catalyst member active component solution-off.Therefore need catalyst to there is good water repelling property.The present invention preferably uses two kinds to have double-deck multi-metal-oxide catalyst, in propylene porch to 1/3 or porch use the internal layer concentration catalyst higher than outer concentration to 1/2 place, as the catalyst of CN201010180103.2, the filling scope of catalyst does not strictly limit, can be less than 1/3 of beds, also can unnecessary 1/3.Because the active component concentration of catalyst outer surface is low, so corresponding activity is also low, therefore can effectively suppress emerging of focus and gathering of heat, reduce the growing amount of accessory substance (as hydrocarbon), improve the selective of object product.Use the catalyst of internal layer concentration lower than outer concentration at residual catalyst bed, the relative entrance of density of propylene is lower, and catalyst activity is high, is more conducive to improve the acrylic acid selective and yield of methacrylaldehyde.And catalyst structure is stable, active component is difficult for running off.Like this, under high-speed reaction condition, two kinds have double-deck catalyst layering filling, it is more reasonable that reaction bed temperature distributes, that the reaction bed temperature of avoiding approaching the port of export declines is fast (bed temperature decline affect catalyst selectively and yield, be unfavorable for the steady running of catalyst long period), make catalyst there is good water repelling property, improve the selective and yield of object product.

Catalyst activity of the present invention is high, is applicable to Propylene Selectivity oxidation acrolein, acrylic acid.Better be along propylene arrival end to port of export beds porch to 1/3 or porch to the scope filling internal layer concentration between 1/2 place the catalyst higher than outer concentration, as the catalyst of CN201010180103.2, the filling scope of catalyst does not strictly limit, can be less than 1/3 of beds, also can unnecessary 1/3.Residual catalyst bed filling catalyst of the present invention.

Evaluating catalyst performance indications are defined as follows:

The specific embodiment

There is double-deck multi-metal-oxide catalyst and preparation method thereof with specific embodiment explanation below, and this catalyst prepares the catalytic performance of methacrylaldehyde (ACR), acrylic acid (AA) in Propylene Selectivity oxidation, but scope of the present invention is not limited to these embodiment.Following examples adopt propylene be propylene content >=99.6%(volume fraction) high concentration propylene.The analytical method of product composition adopts this area universal method.

Embodiment 1:

The preparation of catalyst 1

Step 1: Kaolinite Preparation of Catalyst internal layer parent

(1) preparation of active component slurries (a)

Under stirring condition, get 197 grams of ammonium molybdates and be dissolved in (water temperature is more than 65 ℃) in 1000ml pure water, obtain slurries (1), then get 73 grams of cobalt nitrates, 1.88 grams of potassium nitrate, 112.7 grams of ferric nitrates, 15.1 grams of lanthanum nitrates and be dissolved in (water temperature is more than 65 ℃) in 500ml pure water, fully be uniformly mixed, obtain slurries (2).Get again 45.1 grams of bismuth nitrates, under stirring condition, be dissolved in rare nitric acid, obtain slurries (3).Then, slurries (1) mix with slurries (2), obtain slurries (4), then slurries (3) are added in slurries (4), obtain active component slurries (a).

(2) preparation of catalyst inner layer parent

In active component slurries (a), add 61.4 grams of silicon dioxide powders and 2.5 grams of aluminium oxide, 80 ℃ of strong stirrings carry out heat drying after coprecipitation reaction, in nitrogen with 160 ℃ of heat treatments 3 hours, then be a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2.5mm, dry rear 500 ℃ of roastings 4 hours for 105 ℃, make catalyst Precursors, this catalyst inner layer parent chief component is: Mo ₁₂bi ₁fe ₃co _2.7w ₂k _0.2si ₁₁la _0.5o _x

Step 2: Kaolinite Preparation of Catalyst skin

(1) preparation of active component slurries (a)

Preparation with active component slurries (a) in embodiment 1 catalyst inner layer parent is identical.

(2) preparation of catalyst outer layer

Active component slurries (a) and 11.7 grams of silicon dioxide powders and 4 grams of graphite are carried out to heat drying after coprecipitation reaction, in nitrogen with 150 ℃ of heat treatments 3 hours, then 500 ℃ of roastings 4 hours, process to obtain catalyst outer layer powder through pulverizing, grind, sieving, and outer chief component is:

Mo ₁₂Bi ₁Fe ₃Co _2.7W ₂K _0.2Si _2.1La _0.5O _x。Outer field constituent content is higher by 0.9%～23% than this constituent content of internal layer.

Step 3: Kaolinite Preparation of Catalyst 1

Catalyst inner layer parent prepared by step 1 is placed in round bottom container, under container rotation condition, spray ethanolic solution to catalyst Precursors, under the condition of fully wetting catalyst inner layer parent, stop operating, put it into rapidly in the round bottom container of outer layer catalyst powder that is placed with step 2 gained of another rotation, apply, coating layer thickness is at 0.5～1.5mm, and 100 ℃ of rear 450 ℃ of roastings of oven dry of gained catalyst obtain catalyst 1 for 4 hours.Comparative example 1:

Loading catalyst 1 separately, reaction condition is with the appreciation condition of catalyst 1.

Comparative example 2:

Take the skin of catalyst 1 as comparative catalyst 2, make the ball that diameter is 4mm, reaction condition is with the appreciation condition of catalyst 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 35.7 grams of silica, are a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, and skin adds 6.7 grams of silica and 3.1 grams of carborundum.Coating layer thickness, at 0.5～2.0mm, obtains catalyst 2 for 3 hours through 550 ℃ of roastings.Catalyst 2 internal layer parent chief components are: Mo ₁₂bi ₅fe ₅co ₆w ₃k ₂si _6.4b _0.5o _x, outer chief component is: Mo ₁₂bi ₅fe ₅co ₆w ₃k ₂si _1.2b _0.5o _x.Outer field constituent content is higher by 0.2%～4.6% than this constituent content of internal layer.

Comparative example 3:

Take the internal layer parent of catalyst 2 as comparative catalyst 3, banded extruder extrusion modling is the hollow columnar particle of φ 5 × 5mm, loads separately comparative catalyst 3, and reaction condition is with the appreciation condition of catalyst 1.

Comparative example 4:

Take the skin of catalyst 2 as comparative catalyst 4, banded extruder extrusion modling is the hollow columnar particle of φ 5 × 5mm, and reaction condition is with the appreciation condition of catalyst 1.

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 2.3 grams of carborundum, are the hollow columnar particle of φ 5 × 5mm through banded extruder extrusion modling, and skin adds 28.5 grams of silica.Coating layer thickness, at 0.1～1.5mm, obtains catalyst 3 for 6 hours through 400 ℃ of roastings.Catalyst 3 internal layer parent chief components are: Mo ₁₂bi ₇fe ₁co ₈w _0.3k _3.2si _10.3mn _1.8o _x, outer chief component is:

Mo ₁₂Bi ₇Fe ₁Co ₈W _0.3K _3.2Si _5.1Mn _1.8O _x

Embodiment 4:

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 97.7 grams of silica, are then a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, and skin adds 13.4 grams of silica.Coating layer thickness, at 0.5～2.0mm, obtains catalyst 4 for 5 hours through 480 ℃ of roastings.Catalyst 4 internal layer parent chief components are: Mo ₁₂bi _3.5fe ₄co _4.5w ₁k _0.5si _17.5ti _0.1mg _0.2o _x, outer chief component is: Mo ₁₂bi _3.5fe ₄co _4.5w ₁k _0.5si _2.4ti _0.1mg _0.2o _x.

Embodiment 5:

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 83.7 grams of silica and 3.1 grams of carborundum, are then a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, and skin adds 8.9 grams of silica.Coating layer thickness, at 0.5～2.0mm, obtains catalyst 5 for 3 hours through 560 ℃ of roastings.Catalyst 5 internal layer parent chief components are: Mo ₁₂bi _2.2fe _2.3co _1.2w ₅k _1.4si _15.0la _1.2ba _0.3o _x, outer chief component is: Mo ₁₂bi _2.2fe _2.3co _1.2w ₅k _1.4si _1.6la _1.2ba _0.3o _x.

Comparative example 5:

Loading catalyst 5 separately, reaction condition is with the appreciation condition of catalyst 1.

Comparative example 6:

Separately filling CN201010180103.2 embodiment 3 catalyst, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 6:

Preparation process and primary raw material with embodiment 1 catalyst 1 are identical, and internal layer adds 72.5 grams of silica, are then a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, and skin adds 5.6 grams of silica.Coating layer thickness, at 0.5～2.0mm, obtains catalyst 6 for 4 hours through 500 ℃ of roastings.Catalyst 6 internal layer parent chief components are: Mo ₁₂bi ₃fe ₂co _1.7w ₄k _1.0si _13.0la _2.1sr _0.2ba _0.3o _x, outer chief component is: Mo ₁₂bi ₃fe ₂co _1.7w ₄k _1.0si _1.0la _2.1sr _0.2ba _0.3o _x.

Comparative example 7:

Chief component proportioning according to JP5293389A embodiment 4 is prepared comparative catalyst 7, and preparation process and primary raw material, with embodiment 6, load separately comparative catalyst 7, and reaction condition is with the appreciation condition of catalyst 1.Comparative catalyst 7 chief component is: Mo ₁₂bi ₁fe _1.3co _4.5w _0.8k _0.06si _10.0o _x.

Oxidation reaction

Fixed bed single tube reactor internal diameter 25mm, inside establishes thermocouple, along propylene feed orienting response device bed pack into 15ml CN201010180103.2 embodiment 2 catalyst (F ₁section), the above-mentioned catalyst of 20ml or comparative example catalyst (F ₂section), salt bath heating.From above-mentioned reaction tube porch with air speed 1000h ^-1import the mist of propylene 11 volume %, air 74 volume %, steam 15 volume %.The performance of catalyst as shown in Table 1 and Table 2.React 20 hours and 1000 hours, load beds hot localised points temperature of the present invention not higher than 361 ℃, adopt two kinds of double-layer catalyst segmentation fillings, compare a kind of catalyst of independent filling, it is more reasonable that reaction bed temperature distributes, and avoids the reaction bed temperature that approaches the port of export to decline fast.Methacrylaldehyde and acrylic acid total recovery be more than 90.6%, the difficult losses such as catalyst activity component molybdenum, and catalyst has good water repelling property, catalyst performance stabilised.Comparative example catalyst selectivity is poor, and methacrylaldehyde, acrylic acid yield are low.

Table 1 reacts 20 hours post-evaluation results

Table 2 reacts 1000 hours post-evaluation results

Claims (10)

1. for a catalyst for propylene oxidation, it is characterized in that catalyst chief component is as shown in general formula (I): Mo _abi _bfe _cco _dw _ek _fsi _ga _hb _io _x(I), wherein: silicon is carrier, A is at least one element being selected from titanium, manganese, boron, lanthanum, B is at least one element being selected from alkaline-earth metal, a, b, c, d, e, f, g, h, i represents respectively each element atomic ratio, wherein a is a number of 12, b is a number of 1.0～7, c is a number of 1～6, d is a number of 1～8, e is a number of 0.2～5, f is a number of 0.1～3.2, g is a number of 0.2～55, h is a number of 0.01～2, i is a number of 0～2, x is the numerical value being determined by the oxygen of each oxide, described catalyst has interior outer double-layer structure, every layer of catalyst chief component is identical, silica, the molar concentration difference of one or more in aluminium oxide or carborundum, outer silica, the molar concentration rate internal layer parent of one or more in aluminium oxide or carborundum low, in molar content, the each constituent content concentration ratio of catalyst outer layer internal layer parent is high by 0.1～30%.

2. catalyst according to claim 1, is characterized in that the each constituent content concentration ratio of catalyst outer layer internal layer parent is high by 0.1～15%.

3. catalyst according to claim 1, is characterized in that in general formula (I), A is lanthanum, and h is a number of 0.05～1.5, and i is a number of 0.01～1.2, and catalyst chief component is as shown in general formula (II):

Mo _aBi _bFe _cCo _dW _eK _fSi _gLa _hB _iO _x（Ⅱ）。

4. catalyst according to claim 3, is characterized in that b is a number of 1.0～6.

5. catalyst according to claim 3, is characterized in that c is a number of 1～5.

6. catalyst according to claim 3, is characterized in that d is a number of 1～5, and g is a number of 1～20.

7. catalyst according to claim 1, is characterized in that outer each constituent content is higher by 1～15% than this constituent content of internal layer parent.

8. according to the preparation method of the catalyst described in claim 1～7 any one, it is characterized in that comprising the steps:

1) Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, Bi, A in the compound of Fe, Co, W, K and general formula (I) _hb _ithe each elemental constituent compound relating to dissolves and mixes, and carries out forming internal layer parent slurries after co-precipitation, adds one or more in silica, aluminium oxide or carborundum in slurries preparation process, dry, and moulding, roasting obtains catalyst inner layer parent;

2) prepare outer layer catalyst slurries according to the method for Kaolinite Preparation of Catalyst internal layer parent slurries, in outer preparation process, control one or more the addition in silica, aluminium oxide or carborundum, make in outer layer catalyst slurries each concentration of element 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. the preparation method of catalyst according to claim 8, it is characterized in that internal layer parent after moulding and outer after coating at 400～580 ℃ roasting 3～10h, adopt open roasting or enclosed roasting, calcination atmosphere is helium, nitrogen or argon gas.

10. the preparation method of catalyst according to claim 8, the one in nitrate, ammonium salt, sulfate, oxide, hydroxide, chloride or acetate that the compound that it is characterized in that described each component is each element.