CN102989475B - Multi-metal oxide catalyst and preparation method thereof - Google Patents

Abstract

The invention relates to a multi-metal oxide catalyst with a stratified structure. The composition of the multi-metal oxide catalyst can be represented by the general formula of MoaBibFecNidCoeSifAgBhOi, wherein Mo is molybdenum, Bi is bismuth, Fe is iron, Ni is nickel, Co is cobalt, and Si is silicon. Silicon is a carrier added in the catalyst. A is at least one element selected from tellurium, niobium, boron, manganese, tungsten, and lanthanum. B is at least one element selected from zirconium, vanadium, potassium, and strontium. O is oxygen. With the catalyst provided by the invention, single-pipe reactor local heat accumulation can be effectively reduced, and hot spot formation can be inhibited. The catalyst has the characteristics of high reaction activity, high selectivity, and long service life.

Description

A kind of multi-metal-oxide catalyst and preparation method

Technical field

The present invention relates to multi-metal-oxide catalyst of propylene or the corresponding unsaturated aldehyde of selective isobutene oxidation production and preparation method thereof.More specifically, relate to a kind of catalyst of the poly-metal deoxide with multilayer structure, for catalyzing propone oxidation acrolein or isobutylene oxidation isobutylaldehyde processed.

Background technology

Propylene gas phase catalytic oxidation reaction is exothermic reaction, in beds, can produce focus, 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, even causing 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.Taking 80,000 tons/year of acroleic acid devices as example, propylene oxidation is prepared and in acrolein reaction device, is needed more than 2.5 ten thousand tubulation, acrolein oxidation to prepare in acrylic acid reactor also to need 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 ensures 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.Therefore,, if effectively suppress the generation of beds focus, can bring huge economic benefit to large-scale industrial production.

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.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 DEG C.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.CN1472008A provides a kind of supported catalyst, and this catalyst carrier has multidimensional structure, with the self supporting type multidimensional carrier structure of preformed (as foam, overall structure, fabric or other) or comprise Nb ₂o ₅, cordierite, partially stabilized zirconia, ceramic fibre or its mixture carrier, in succession on described carrier deposition comprise any order at least one molybdenum-containing layer, at least one containing vanadium layer, at least one forms load carrier containing tellurium layer and at least one containing the carbon monoxide-olefin polymeric of X layer, after roasting supported catalyst.Be oxidized to unsaturated carboxylic acid for alkane and become unsaturated nitrile with ammoxidation of paraffins, enough conversion ratios are provided and are applicable to selective.CN200810090707.0 discloses a kind of oxide catalyst, prepare methacrylaldehyde or acrylic acid and prepare the method for water-absorbing resins.The method is used single plants catalyst and the appearance of local extra high temperature spot (focus) and can keep long-term and stably high methacrylaldehyde or acrylic acid yield in can suppressing catalyst layer in preparing acrylic acid by the catalytic vapor phase oxidation of methacrylaldehyde in making to prepare methacrylaldehyde by the catalytic vapor phase oxidation of propylene under the existence of the gas of molecular oxygen or molecule-containing keto or under the existence of the gas of molecular oxygen or molecule-containing keto.The method is characterised in that to use and contains the oxide catalyst that molybdenum is 0.02-0.20 as solvent and its particle size relative standard deviation, carrys out hot localised points in inhibition layer by the size of controlling catalyst.Catalyst consists of: (wherein Mo is molybdenum to Mo12BiaFebAcBdCeDfOx (2), Bi is bismuth, and Fe is iron, and A is the element that is at least selected from cobalt and nickel, 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.CN200480000597.4 discloses a kind of for effectively and stably alkene or unsaturated aldehyde gaseous oxidation are become with molecular oxygen to the production method of the composite oxide catalysts of corresponding unsaturated aldehyde and/or unsaturated carboxylic acid with commercial scale, this catalyst has evenly constant high-performance, the consisting of of catalyst: Mo _abi _bco _cni _dfe _ex _fy _gz _hq _isi _jo _k, X represents that at least one is selected from the element of Na, K, Rb, Cs and Ti, and Y represents that at least one is selected from the element of B, P, As and W, and Z represents that at least one is selected from the element of Mg, Ca, Zn, Ce and Sm, and Q represents halogen atom.The method comprises by the step of the powder compacting containing catalytic component with by the step of the shaped article calcining obtaining in forming step, wherein, forming step is: be that 10-50 μ m and the initiation temperature that burns in differential thermogravimetry at least add in the powder containing catalytic component than the graphite granule of high 50 DEG C of the calcining heat in next calcining step by average particulate diameter D50, its addition is the 0.5-10wt% of powder, then moulding; Calcining step is: minimum be 250 DEG C and at least than the temperature of low 50 DEG C of the burning initiation temperature of graphite granule under calcine.CN200480000345.1 provides a kind of Catalysts and its preparation method of being prepared with high yield corresponding unsaturated aldehyde and unsaturated carboxylic acid by alkene, and catalyst is composed as follows: Mo _abi _bco _cni _dfe _ex _fy _gz _hq _isi _jo _kthis catalyst is for preparing respectively corresponding unsaturated aldehyde and unsaturated carboxylic acid by alkene being carried out to catalytic gas phase oxidation containing the gas of molecular oxygen, it at least comprises (A) molybdenum, (B) bismuth, (C) cobalt and/or nickel and (D) iron, it is characterized in that, in the preparation method of this catalyst, containing through integrated aforementioned (A) composition raw material, (C) composition raw material and (D) composition raw material, and the content of nitrate anion meets following formula (1): 1.2≤NO ₃the aqueous dispersions of/(3 × Fe+2 × (Co+Ni)) is dried, the catalyst precursor powder making by this dry thing being carried out to the front operation of heat treated, in aqueous solvent, carry out integratedly with aforementioned (B) composition raw material, this one compound is dried, is burnt till.In formula (1), NO ₃, Fe, Co and Ni represent respectively the molar content of nitrate anion, iron, cobalt and nickel in above-mentioned aqueous dispersions.

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.In addition, under hot conditions, in catalyst, part active component molybdenum loses because of distillation from catalyst surface.Washing away of propylene, air and steam mixed airflow also can make the loss of active component 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 taking 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.

Summary of the invention

The object of this invention is to provide multi-metal-oxide catalyst of a kind of propylene or the corresponding unsaturated aldehyde of selective isobutene oxidation production and preparation method thereof.Different from the method for above-mentioned reduction focus, there is gradient difference from inside to exterior active combination of components substrate concentration in catalyst granules of the present invention, can effectively reduce single tube reactor localized heat and gather, and suppresses emerging of focus.This catalyst has the feature of reactivity and selective height, long service life.

The present invention relates to a kind of multi-metal-oxide catalyst, the chief component of this catalyst is by general formula (I) expression below

Mo _aBi _bFe _cNi _dCo _eSi _fA _gB _hO _i (I)

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Ni is nickel, and Co is cobalt, and Si is silicon, and silicon is the carrier adding in catalyst, and A is at least one element being selected from tellurium, niobium, boron, manganese, tungsten, lanthanum, B is at least one element in selected among zirconium, vanadium, potassium, strontium, O is oxygen, a, b, c, d, e, f, g, h represent respectively each element atomic ratio, and wherein a is a number of 12～14, and b is a number of 2～10, preferably 3～7, c is a number of 1～6, d is a number of 1～6, e is a number of 1～5, f is a number of 0.5～55, g is a number of 0～5, h is a number of 0～5, i is the numerical value being determined by the oxygen of each oxide, described multi-metal-oxide catalyst has multilayer structure, outer double-layer structure in, every layer of catalyst chief component is identical, but silica, the total content difference of one or more in aluminium oxide or carborundum, outer silica, the total content of one or more in aluminium oxide or carborundum is than the height of internal layer parent, in molar content, the each constituent content concentration ratio of catalyst outer layer internal layer parent is low.

Catalyst of the present invention is multilayer structure, there is gradient difference from inside to exterior active combination of components substrate concentration in catalyst, mainly by add the materials such as different amount silica, aluminium oxide, carborundum to be achieved concentration difference at ectonexine, that is to say, the total content of one or more in outer silica, aluminium oxide or carborundum is higher than internal layer parent, in molar content, outer each constituent content is lower by 0.5～30% than this constituent content of internal layer, and preferably 1～15%.Catalyst inner layer of the present invention also can not add silicon.

In catalyst of the present invention, preferably add lanthanum, lanthanum and molybdenum, nickel, cobalt etc. can form stable crystal phase structure, thereby suppressing part active component molybdenum loses because of distillation from catalyst surface, before and after catalyst reaction, active component molybdenum content is substantially constant, delay active deterioration rate, catalyst activity and good stability.The general formula for composition (II) of catalyst represents.

Mo _aBi _bFe _cNi _dCo _eSi _fLa _gB _hO _i (II)

Wherein a is a number of 12, and b is a number of 4～7, and c is a number of 1～3, and d is a number of 1～4, and e is that 2～4, f is a number of 0.5～30, and g is a number of 0.1～2, and h is a number of 0.1～2.

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

First, Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, Bi, A in the compound of Fe, Ni, Co and Si and general formula (I) _gb _hthe each elemental constituent compound relating to dissolve and mix, carry out forming internal layer parent slurries after co-precipitation, dry, moulding, roasting obtains catalyst inner layer parent;

Secondly, method according to Kaolinite Preparation of Catalyst internal layer parent slurries is prepared outer layer catalyst slurries, in outer layer catalyst slurries preparation process, add one or more in silica, aluminium oxide or carborundum, make in outer layer catalyst slurries each concentration of element lower than the concentration of this element of adjacent inner layer;

Finally, the 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 300～580 DEG C 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 DEG C of oven dry, and then roasting.The outer layer catalyst bed thickness that is coated on internal layer parent is 1.0～2.5mm, preferably 1.5～2mm.

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.Active component is not all used nitrate as far as possible, the oxide contaminant atmosphere producing in the time of roasting, and be not easy moulding, manufacturing schedule is slow, but nitrate is easy to dissolve, and nitrate preferably uses together with other forms of compound, be easy to moulding, speed production efficiency.

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 multi-metal-oxide 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.

Because catalyst initial reaction activity is very high, thus on fixed bed single tube reactor bed, be easy to produce focus or produce heat localization, the easy sintering of catalyst, 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.

The present invention has the multi-metal-oxide catalyst of multilayer structure by preparation, make catalyst granules have gradient difference from inside to exterior active combination of components substrate concentration, and catalyst outer layer active component concentration is lower than its internal layer active component concentration, like this, even under high-speed reaction condition, 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.This has double-deck catalyst and has good water repelling property.And when after catalyst runs a period of time, catalyst has release effects, under mixed airflow long period washes away, even if catalyst surface active component has part to run off, but because internal layer catalyst active component concentration is higher, can play supplementary effect, so can keep catalyst activity lasting stability.

The catalyst that the present invention also can adopt chief component to be represented by following formula (III): a kind of multi-metal-oxide catalyst (III), this catalyst has double-decker, represents respectively to outer chief component from catalyst inner layer by general formula (i) with (ii).

Mo _aBi _bFe _cNi _dLa _eCo _fSi _gA _mB _nO _x (i)

Mo _aBi _bFe _cNi _dSi _g (ii)

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Ni is nickel, and La is lanthanum, and Co is cobalt, and Si is silicon, and silicon is the carrier adding, and A is at least one element being selected from strontium, potassium, titanium, manganese, B is at least one element being selected from zinc, tungsten, magnesium and boron, O is oxygen, Si is silicon, silicon is the carrier adding, a, b, c, d, e, f, g, m, n represents respectively each element atomic ratio, wherein in the time that a=12 is benchmark, b is a number of 2～8, c is a number of 0.5～6, d is a number of 0.5～3, e is a number of 0.05～3, f is a number of 0.05～5, g is a number of 0.5～20, m is a number of 0.05～3, n is a number of 0.05～3, x is the numerical value being determined by the oxygen of each oxide, described compound multi-metal-oxide catalyst has double-decker, lanthanum and nickel, cobalts etc. can form stable crystal phase structure, being conducive to suppress part active component molybdenum loses because of distillation from catalyst surface, before and after catalyst reaction, active component molybdenum content is substantially constant, delay active deterioration rate, catalyst activity and good stability.

The catalyst that the present invention can also adopt chief component to be represented by following formula (IV): a kind of multi-metal-oxide catalyst (IV), this catalyst has double-decker, represents respectively to outer chief component from catalyst inner layer by general formula (i) with (ii).

Mo _aBi _bFe _cCo _dNi _eCu _fSi _gA _mB _nO _x (i)

Mo _aBi _bFe _cCo _dSi _g (ii)

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Co is cobalt, and Ni is nickel, and Cu is copper, and Si is silicon, and silicon is the carrier adding, and A is at least one element being selected from alkali metal or alkaline-earth metal; B is at least one element being selected from zinc, cerium, boron; O is oxygen; Si is silicon, and silicon is the carrier adding, and a, b, c, d, e, f, g, m, n represent respectively each element atomic ratio, wherein in the time that a=12 is benchmark, b is a number of 2～7, and c is a number of 0.5～6, and d is a number of 0.5～5, e is a number of 0.05～5, f is a number of 0.05～6, and g is a number of 0.5～20, and m is a number of 0.05～3, n is a number of 0.05～3, and x is the numerical value being determined by the oxygen of each oxide.

The catalyst granules representing with (III), (IV) successively reduces part active component from body mutually to table, that is to say that catalyst is by showing successively to increase mutually the active component with difference in functionality to body mutually, outer except rising four kinds of components such as molybdenum, bismuth of main active function, one or both in activity inhibitor silicon and aluminium are only added, active component is few, corresponding activity is also minimum, the unstripped gas of high concentration first contacts with catalyst outer layer, moment reaction produces a large amount of heat, compares high activity internal layer catalyst and is difficult for producing focus.Internal layer active component relatively skin increases, and its corresponding activity is also high, on single catalyst particle, has dilution effect, effectively suppresses focus and emerges the heat localization that generates in a large number formation with byproduct of reaction.Have, even catalyst outer surface activity declines to some extent after some cycles running, also needn't unload catalyst, by simple activation processing, internal layer catalyst body phase active material can play supplementary effect, makes catalyst operation steady in a long-term.

The invention provides the preparation method that corresponding unsaturated aldehyde is produced in a kind of propylene or selective isobutene oxidation.

The method of Propylene Selectivity oxidation acrolein provided by the invention is as follows: adopt fixed bed single tube reactor; Reaction raw materials propylene, water, air more than 140 DEG C enter reactor after preheating through preheater, salt bath heating, and reaction process condition is: 290～345 DEG C of salt temperatures, preferably 300～335 DEG C; Air speed 800～2400h ^-1, preferably 800～1600h ^-1, feed composition: propylene 7～14 volume %, air 68～74 volume %, steam 14～20%; Catalyst (III) or (IV) is housed in reactor.Propylene conversion is between 98.2～99.4%, and methacrylaldehyde is selectively between 85.0～88.2%.Hot(test)-spot temperature is between 360～385 DEG C.

Evaluating catalyst performance indications are defined as follows:

Molal quantity × 100% of propylene in the total mole number/raw material of propylene conversion (%)=propylene reaction

Selective (the %)=propylene of methacrylaldehyde is converted into total mole number × 100% of molal quantity/propylene reaction of methacrylaldehyde

Detailed description of the invention

There is the Catalysts and its preparation method of multilayer structure below with specific embodiment explanation, and this catalyst produces the catalytic performance of methacrylaldehyde in Propylene Selectivity oxidation, but scope of the present invention is not limited to these embodiment.The propylene that following examples adopt is the high concentration propylene of propylene content >=99.6% (volume fraction).

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 160 grams of ammonium molybdates and be dissolved in (water temperature is more than 65 DEG C) in 500ml pure water, obtain slurries (1), then get 40.7 grams of cobalt nitrates, 61.1 grams of nickel nitrates, 7 grams of potassium nitrate, 113 grams of ferric nitrates and be dissolved in (water temperature is more than 65 DEG C) in 500ml pure water, fully be uniformly mixed, obtain slurries (2).Get again 237.7 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 10.8 grams of silica, 80 DEG C of strong stirrings carry out heat drying after coprecipitation reaction for 2 hours, in nitrogen with 160 DEG C of heat treatments 3 hours, then be the hollow columnar particle of φ 4.5 × 5mm through banded extruder extrusion modling, dry rear 450 DEG C of roastings 4 hours for 75 DEG C, make catalyst Precursors, this catalyst inner layer parent consists of: Mo ₁₃bi ₇co ₂fe ₄ni ₃k ₁si _2.6

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 23.6 grams of silica powders are carried out to coprecipitation reaction heat drying after 40 minutes, and in nitrogen, with 150 DEG C of heat treatments 3 hours, then 500 DEG C of roastings 4 hours, processed to obtain catalyst outer layer powder through pulverizing, grind, sieving.

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, at 1.0～2.0mm, obtains catalyst 1 for 4 hours through 450 DEG C of roastings after 65 DEG C of oven dry of gained catalyst.

Comparative example 1:

Taking the internal layer parent of catalyst 1 as comparative catalyst 1, be then the hollow columnar particle of φ 5 × 5mm through banded extruder extrusion modling, reaction condition is with the appreciation condition of catalyst 1.

Comparative example 2:

Taking the skin of catalyst 1 as comparative catalyst 2, be then the hollow columnar particle of φ 5 × 5mm through banded extruder extrusion modling, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 2:

The preparation of catalyst 2

Step 1: Kaolinite Preparation of Catalyst internal layer parent

(1) preparation of active component slurries (a)

Under stirring condition, get 173 grams of ammonium molybdates and be dissolved in (water temperature is more than 65 DEG C) in 500ml pure water, obtain slurries (1), then get 30.6 grams of cobalt nitrates, 81.4 grams of nickel nitrates, 17.4 grams of ammonium phosphotungstates, 183.8 grams of ferric nitrates and be dissolved in (water temperature is more than 65 DEG C) in 500ml pure water, fully be uniformly mixed, obtain slurries (2).Get again 169.8 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 Precursors

In slurries (a), add 8.3 grams of silica, 80 DEG C of strong stirrings carry out heat drying after coprecipitation reaction for 2 hours, in nitrogen with 160 DEG C of heat treatments 3 hours, then be the hollow columnar particle of φ 4.5 × 5mm through banded extruder extrusion modling, dry rear 450 DEG C of roastings 4 hours for 95 DEG C, make catalyst Precursors, this catalyst Precursors consists of: Mo ₁₄bi ₅co _1.5fe _6.5ni ₄w ₁

Step 2: Kaolinite Preparation of Catalyst skin

(1) preparation of active component slurries (a)

Preparation with active component slurries (a) in embodiment 2 catalyst inner layer parents is identical.

(2) preparation of catalyst outer layer

Active component slurries (a) and 28.4 grams of silica powders are carried out answering after co-precipitation heat drying after 50 minutes, and in nitrogen, with 160 DEG C of heat treatments 3 hours, then 500 DEG C of roastings 4 hours, processed to obtain catalyst outer layer powder through pulverizing, grind, sieving.

Step 3: Kaolinite Preparation of Catalyst 2

Catalyst inner layer parent prepared by step 1 is placed in round bottom container, under container rotation condition, spray ethanolic solution to catalyst Precursors, fully wetting catalyst inner layer parent, put it into rapidly in the round bottom container of the catalyst outer layer that is placed with step 2 gained of another rotation, apply, coating layer thickness is in the time of 0.8～1.0mm, taking-up internal layer parent is put into another round bottom container rotation and is sprayed ethanolic solution after one to two minute again, then put into the round bottom container continuation coating that catalyst outer layer is housed, until coating layer thickness stops applying in the time of 0.5～2.0mm, after 125 DEG C of oven dry of gained catalyst, within 3 hours, obtain catalyst 2 through 500 DEG C of roastings.

Comparative example 3:

Taking the internal layer parent of catalyst 2 as comparative catalyst 3, be then the hollow columnar particle of φ 4.5 × 5mm through banded extruder extrusion modling, reaction condition is with the appreciation condition of catalyst 1.

Comparative example 4:

Taking the skin of catalyst 2 as comparative catalyst 4, be then the hollow columnar particle of φ 4.5 × 5mm through banded extruder extrusion modling, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 3:

Step 1: Kaolinite Preparation of Catalyst internal layer parent

(1) preparation of active component slurries (a)

The preparation method of active component slurries (a) and raw materials used same embodiment 1 (following examples are also identical), add 10.9 grams of cesium nitrates, 26.1 grams of ammonium metavanadates.

(2) preparation of catalyst inner layer parent

In slurries (a), add 15 grams of silica, 80 DEG C of strong stirrings carry out heat drying after coprecipitation reaction for 2 hours, in nitrogen with 160 DEG C of heat treatments 3 hours, then be a granulated into through banded extruder extruding, rolling the ball shape that diameter is 2mm, dry rear 450 DEG C of roastings 4 hours for 105 DEG C, make catalyst Precursors, this catalyst inner layer parent consists of: Mo ₁₃bi ₃co ₄fe ₄ni ₆w _1.5cs _0.8

Step 2: Kaolinite Preparation of Catalyst skin

(1) preparation of active component slurries (a)

Preparation with active component slurries (a) in embodiment 3 catalyst inner layer parents is identical.

(2) preparation of catalyst outer layer

Active component slurries (a) and 40.2 grams of silica powders and 5 grams of graphite powders are carried out answering after co-precipitation heat drying after 50 minutes, in nitrogen with 160 DEG C of heat treatments 3 hours, then 500 DEG C of roastings 4 hours, process to obtain catalyst outer layer powder through pulverizing, grind, sieving.

Step 3: Kaolinite Preparation of Catalyst 3

Catalyst inner layer parent prepared by step 1 is placed in round bottom container, under container rotation condition, spray diethyl ether 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 the catalyst outer layer that is placed with step 2 gained of another rotation, apply, coating layer thickness, at 1.0～2.0mm, obtains catalyst 3 for 3 hours through 550 DEG C of roastings after 80 DEG C of oven dry of gained catalyst.

Comparative example 5:

Taking the internal layer parent of catalyst 3 as comparative catalyst 5, make the ball that diameter is 4mm, reaction condition is with the appreciation condition of catalyst 1.

Comparative example 6:

Taking the skin of catalyst 3 as comparative catalyst 6, make the ball that diameter is 4mm, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 4:

Step 1: Kaolinite Preparation of Catalyst internal layer parent

Preparation method with embodiment 2 catalyst inner layer parents is identical, but adds 10.2 grams of magnesium nitrates, 8.3 grams of silica, and this catalyst inner layer parent consists of: Mo ₁₂bi ₈co ₃fe _1.5ni ₂mg _0.8k _1.2

Step 2: Kaolinite Preparation of Catalyst skin

Preparation with embodiment 2 catalyst outer layer is identical, but adds 21.4 grams of silica and 12.6 grams of graphite.

Step 3: Kaolinite Preparation of Catalyst 4

Catalyst inner layer parent prepared by step 1 is placed in round bottom container, under container rotation condition, spray ethanolic solution to catalyst, under the condition of fully wetting catalyst inner layer parent, spray the outer layer catalyst powder of step 2 gained, apply, coating layer thickness, at 0.8～1.5mm, obtains catalyst 4 for 5 hours through 450 DEG C of roastings after 50 DEG C of oven dry of gained catalyst.

Comparative example 7:

Taking the outer layer catalyst of catalyst 4 as comparative catalyst 7, make the ball that diameter is 4mm, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 5:

Step 1: Kaolinite Preparation of Catalyst internal layer parent

Preparation with embodiment 2 catalyst inner layer parents is identical, adds 4.6 grams of lanthanum nitrates, 7.3 grams of silica, and this catalyst inner layer parent consists of: Mo ₁₂bi ₉co ₆fe ₃ni ₄k ₁la _0.2

Step 2: Kaolinite Preparation of Catalyst skin

Preparation with embodiment 2 catalyst outer layer is identical, adds 10.5 grams of silica and 8.7 grams of aluminium oxide.

Step 4: apply time outer layer catalyst

Catalyst inner layer parent prepared by step 1 is placed in round bottom container, under container rotation condition, spray distilled water to catalyst Precursors, under the condition of fully wetting catalyst inner layer parent, spray the inferior outer layer catalyst powder of step 2 gained, apply, coating layer thickness is at 0.8～1.2mm, for subsequent use through 500 DEG C of roastings 6 hours after 50 DEG C of oven dry of gained catalyst.

Step 5: Kaolinite Preparation of Catalyst 5

Catalyst prepared by step 4 is placed in round bottom container, under container rotation condition, spray ethanolic solution to catalyst, under the condition of fully wetting catalyst inner layer parent, spray the outermost layer catalyst fines of step 2 gained, apply, coating layer thickness, at 1.0～1.5mm, obtains catalyst 5 for 6 hours through 500 DEG C of roastings after 95 DEG C of oven dry of gained catalyst.

Comparative example 8:

Taking the internal layer catalyst of catalyst 5 as comparative catalyst 8, but catalyst does not contain lanthanum, consists of Mo ₁₂bi ₉co ₆fe ₃ni ₄k ₁, reaction condition is with the appreciation condition of catalyst 1.

Embodiment 6:

With the preparation method of embodiment 5 catalyst and raw materials used identical, internal layer adds 13 grams of silica, and skin adds 10 grams of carborundum and 15.6 grams of silica, and catalyst inner layer parent consists of:

Mo ₁₂Bi _4.5Co _2.5Fe _1.2Ni ₂K _0.8La _1.2

Embodiment 7:

With the preparation method of embodiment 6 catalyst and raw materials used identical, internal layer adds 6 grams of silica, and skin adds 9 grams of carborundum and 15.6 grams of silica, and catalyst inner layer parent consists of: Mo ₁₂bi _4.5co _2.5fe _1.2ni ₂.Reaction condition is with the appreciation condition of catalyst 1.

Oxidation reaction

Fixed bed single tube reactor internal diameter 20mm, inside establishes thermocouple, and reactor feedstocks gas entrance side packs the above-mentioned catalyst of 30ml, salt bath heating into.From above-mentioned reaction tube porch with air speed 1000h ^-1import the mist of propylene 8 volume %, air 72 volume %, steam 20 volume %.Reaction result as shown in Table 1 and Table 2.Catalyst effectively suppresses focus, and catalyst reaction front and back active component molybdenum etc. does not run off substantially, after running in 1000 hours, and active, selective kept stable.Comparative example 1～8 catalyst can not effectively suppress focus, and poor selectivity is reacted after 1000 hours rear catalysts activity under the washing away of the mixed airflows such as steam and obviously declined.

Table 1 reacts 20 hours post-evaluation results

Table 2 reacts 1000 hours post-evaluation results

Claims (9)

1. a multi-metal-oxide catalyst, is characterized in that catalyst chief component is as shown in general formula (I): Mo _abi _bfe _cni _dco _esi _fa _gb _ho _i(I)

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Ni is nickel, and Co is cobalt, and Si is silicon, and silicon is the carrier adding in catalyst, and A is at least one element being selected from tellurium, niobium, boron, manganese, tungsten, lanthanum, B is at least one element in selected among zirconium, vanadium, potassium, strontium, O is oxygen, a, b, c, d, e, f, g, h represents respectively each element atomic ratio, wherein a is a number of 12～14, b is a number of 2～10, c is a number of 1～6, d is a number of 1～6, e is a number of 1～5, f is a number of 0.5～55, g is a number of 0～5, h is a number of 0～5, i is the numerical value being determined by the oxygen of each oxide, described multi-metal-oxide catalyst has interior outer double-layer structure, outer silica, the total content of one or more in aluminium oxide or carborundum is than the height of internal layer parent, in molar content, the each constituent content concentration ratio of catalyst outer layer internal layer parent is low.

2. catalyst according to claim 1, is characterized in that b is a number of 3～7.

3. catalyst according to claim 1, is characterized in that catalyst is interior outer double-layer structure, and in molar content, outer each constituent content is lower by 0.5～30% than this constituent content of internal layer.

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

5. catalyst according to claim 1, is characterized in that A is lanthanum, and the general formula for composition (II) of catalyst represents Mo _abi _bfe _cni _dco _esi _fla _gb _ho _i(II)

Wherein a is that 12, b is a number of 4～7, and c is a number of 1～3, and d is a number of 1～4, and e is that 2～4, f is a number of 0.5～30, and g is a number of 0.1～2, and h is a number of 0.1～2.

6. according to the preparation method of the catalyst described in claim 1～5 any one, it is characterized in that comprising the steps:

First, Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, Bi, A in the compound of Fe, Ni, Co and Si and general formula (I) _gb _hthe each elemental constituent compound relating to dissolve and mix, carry out forming internal layer parent slurries after co-precipitation, dry, moulding, roasting obtains catalyst inner layer parent;

Secondly, prepare outer layer catalyst slurries according to the method for Kaolinite Preparation of Catalyst internal layer parent slurries, in outer layer catalyst slurries preparation process, add one or more in silica, aluminium oxide or carborundum;

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

7. the preparation method of catalyst according to claim 6, it is characterized in that internal layer parent after moulding and outer after coating at 300～580 DEG C roasting 3～10h, adopt open roasting or enclosed roasting, calcination atmosphere is helium, nitrogen or argon gas.

8. the preparation method of catalyst according to claim 6, is characterized in that when described catalyst applies using binding agent, binding agent to be selected from one or more in water, Ludox or aluminium colloidal sol.

9. a multi-metal-oxide catalyst, is characterized in that this catalyst has double-decker, represented by general formula (I) and (II) respectively to outer chief component from catalyst inner layer,

Mo _aBi _bFe _cCo _dNi _eCu _fSi _gA _mB _nO _x (ⅰ)

Mo _aBi _bFe _cCo _dSi _g (ⅱ)

Wherein: Mo is molybdenum, Bi is bismuth, and Fe is iron, and Co is cobalt, and Ni is nickel, and Cu is copper, and Si is silicon, and silicon is the carrier adding, and A is at least one element being selected from alkali metal or alkaline-earth metal; B is at least one element being selected from zinc, cerium, boron; O is oxygen; Si is silicon, and silicon is the carrier adding, and a, b, c, d, e, f, g, m, n represent respectively each element atomic ratio, wherein in the time that a=12 is benchmark, b is a number of 2～7, and c is a number of 0.5～6, and d is a number of 0.5～5, e is a number of 0.05～5, f is a number of 0.05～6, and g is a number of 0.5～20, and m is a number of 0.05～3, n is a number of 0.05～3, and x is the numerical value being determined by the oxygen of each oxide.