CN102989475A - 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 propylene or multi-metal-oxide catalyst of corresponding unsaturated aldehyde and preparation method thereof is produced in the selective isobutene oxidation.More specifically, relate to a kind of catalyst with poly-metal deoxide of multilayer structure, be used for catalyzing propone oxidation acrolein or isobutylene oxidation isobutylaldehyde processed.

Background technology

The propylene gas phase catalytic oxidation reaction is exothermic reaction, in beds, can produce focus, the heat that moment is gathered is constantly accumulated, to cause the catalyst activity component loss, come off, to such an extent as to catalyst activity reduction, the lost of life, and cause aggravating the formation of accessory substance because of over oxidation reaction, even cause and runaway reaction make sintering of catalyst.

The appearance of " progress of oxidation acrylic acid synthesizing process and catalyst " (petrochemical industry, the 7th phase of the 39th volume in 2010) social focus also can make the catalyst damage evil, shortens the service life of catalyst.Take 80,000 ton/years of acroleic acid devices as example, propylene oxidation prepares and needs more than 2.5 ten thousand tubulation in the acrolein reaction device, and acrolein oxidation prepares also needs more than 2.5 ten thousand tubulation in the acrylic acid reactor, load altogether more than 100 ton of methacrylaldehyde, acrylic acid catalyst.More than 50,000 reaction tube, the filling of catalyst guarantee 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, carry out under cryogenic conditions as much as possible for methacrylaldehyde, acrylic acid production, because the reaction needed salt bath heating, its energy resource consumption of keeping production also is huge spending; Because the generation of focus is high temperature resistant to the requirement of reaction tube tubing, for up to ten thousand reaction tubes, the tubing expense is exactly a very large cost.Therefore, if the generation of establishment 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 a kind of method that suppresses the appearance of focus or the hot polymerization collection on the focus, namely by preparing multiple catalyst with different possessive volumes, and the mode from the unstripped gas inlet side to the minimizing of outlet one side catalyst possessive volume, fill successively reaction tube, but the possessive volume of catalyst is subjected 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 with different activities in reaction tube, according to active uprise arranged sequentially above-mentioned several catalyst-loaded from the entrance of unstripped gas to outlet.The method that other is also arranged, for example inert substance and catalyst mix, reduce the activity of catalyst, be loaded into the reactor inlet place, Japan special permission disclose 10614/1972 to sneak into heat resistanceheat resistant point formation catalyst in catalyst is inert substance with catalyst dilution, and Japanese Patent Publication 36739/1987 is made catalyst the method for tubulose.The Catalyst packing that the unstrpped gas porch reduces with active component is arranged again.CN1672790A provides a kind of catalyzing propone aldehyde gaseous oxidation system acrylic acid catalyst, described catalyst comprises molybdenum and vanadium, also comprise at least a 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, comprises and originally has in the highly active catalyst by the volatility toxic component that makes specified quantitative, and catalytic activity descends momently, can reduce the temperature of hot spot.CN1165055A by catalytic active component is divided be loaded on the carrier after, calcine the generation that the catalyst of load sharing suppresses focus, the average grain diameter of catalyst is 4～16mm, the average grain diameter of carrier is 3～12mm, calcining heat is 500～600 ℃.CN1314331A provides the catalyst of a kind of Mo-W-Bi-Fe of containing, this catalyst by changing possessive volume calcining heat and/or alkali metal kind and/or quantity and according to catalyst activity from the inlet side of unstripped gas to the mode that outlet one side increases, fill successively reaction zone with described multiple types catalyst.Catalyst reaction tube axially on be divided at least two-layerly, 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.The appearance of focus or the hot polymerization collection on the focus are by establishment.CN1472008A provides a kind of supported catalyst, and this catalyst carrier has multidimensional structure, with the self supporting type multidimensional carrier structure of preformed (such as foam, overall structure, fabric or other) or comprise Nb ₂O ₅, cordierite, partially stabilized zirconia, ceramic fibre or its mixture carrier, in succession described carrier deposition comprise any order at least one molybdenum-containing layer, at least one contains the vanadium layer, at least one contains the carbon monoxide-olefin polymeric that tellurium layer and at least one contain the X layer and forms the load carrier, 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 fit 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 use single plant catalyst and so that in the presence of the gas of molecular oxygen or molecule-containing keto the catalytic vapor phase oxidation by propylene prepare in the methacrylaldehyde or in the presence of the gas of molecular oxygen or molecule-containing keto the catalytic vapor phase oxidation by methacrylaldehyde prepare the appearance that can suppress local extra high temperature spot (focus) in the catalyst layer in the acrylic acid and can keep long-term and stably high methacrylaldehyde or acrylic acid yield.The method is characterised in that to use and contains molybdenum as solvent and its particle size relative standard deviation oxide catalyst as 0.02-0.20, and the size by the control catalyst suppresses hot localised points in the layer.Catalyst consists of: (wherein Mo is molybdenum to Mo12BiaFebAcBdCeDfOx (2), Bi is bismuth, and Fe is iron, and A is the element that is selected from least cobalt and nickel, B is the element that is selected from least alkali metal, alkaline-earth metal and thallium, and C is the element that is selected from least tungsten, silicon, aluminium, zirconium and titanium; D is the element that is selected from least 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, and 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 of being determined by the oxidation state of respective element.CN200480000597.4 discloses a kind of production method for effectively and stably with molecular oxygen alkene or unsaturated aldehyde gaseous oxidation are become 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 the element of at least a Na of being selected from, K, Rb, Cs and Ti, and Y represents the element of at least a B of being selected from, P, As and W, and Z represents the element of at least a Mg of being selected from, Ca, Zn, Ce and Sm, and Q represents halogen atom.The method comprise with contain catalytic component powder compacting step and with the step of the shaped article that obtains in forming step calcining, wherein, forming step is: with average particulate diameter D50 be 10-50 μ m and in the differential thermogravimetry burning initiation temperature add than the high 50 ℃ graphite granule of the calcining heat in the next calcining step at least and contain in the powder of catalytic component, its addition is the 0.5-10wt% of powder, then moulding; Calcining step is: be 250 ℃ and calcine under the temperature than low 50 ℃ of the burning initiation temperature of graphite granule at least minimum.CN200480000345.1 provides a kind of and prepares with high yield the Catalysts and its preparation method of 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 used for by the gas that contains molecular oxygen alkene being carried out catalytic gas phase oxidation and prepares respectively corresponding unsaturated aldehyde and unsaturated carboxylic acid, it comprises (A) molybdenum, (B) bismuth, (C) cobalt and/or nickel and (D) iron at least, 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 satisfies following formula (1): 1.2≤NO ₃The aqueous dispersions of/(3 * Fe+2 * (Co+Ni)) carries out drying, the catalyst precursor powder that makes by the front operation of this drying thing being carried out heat treated, in aqueous solvent, carry out integratedly with aforementioned (B) composition raw material, this one compound is carried out drying, burnt till.In the formula (1), NO ₃, Fe, Co and Ni represent respectively the molar content of nitrate anion, iron, cobalt and nickel in the above-mentioned aqueous dispersions.

All there is a problem in the method that above-mentioned inhibition focus produces, the catalyst that is filled in the reaction tube all has been diluted with various forms from the inlet to the outlet, active decline also can not change thinner ratio after both having made the catalyst runs some cycles, catalyst also can't 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, part active component molybdenum loses because of distillation from catalyst surface in the catalyst.Propylene, air and steam mixed airflow wash away the loss of active component that also can make in the catalyst.For the loss that suppresses the molybdenum distillation causes active decay, CN1121504 can suppress dissipation effect and the over reduction of molybdenum composition by mixing copper component and zirconium and/or Titanium and/or Cerium with specified particle diameter and specific area; CN1445020 adds a small amount of tellurium and plays stable free molybdenum trioxide and the effect of molybdic acid copper crystal structure, and 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 consist of with other element form the loss that catalyst suppresses molybdenum.

Summary of the invention

The purpose of this invention is to provide a kind of propylene or multi-metal-oxide catalyst of corresponding unsaturated aldehyde and preparation method thereof is produced in the selective isobutene oxidation.Different from the method for above-mentioned reduction focus, there is gradient difference in catalyst granules of the present invention to exterior active combination of components substrate concentration internally, can effectively reduce the single tube reactor localized heat and gather, and suppresses emerging of focus.This catalyst has the characteristics 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 represented by following general formula (I)

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

Wherein: Mo is molybdenum, and Bi is bismuth, and Fe is iron, and Ni is nickel, and Co is cobalt, and Si is silicon, and silicon is the carrier that adds in the catalyst, and A is at least a element that is selected from tellurium, niobium, boron, manganese, tungsten, the lanthanum; B is at least a element in selected among zirconium, vanadium, potassium, the 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, preferred 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 by the oxygen decision of each oxide, described multi-metal-oxide catalyst has multilayer structure, namely in outer double-layer structure, every layer of catalyst chief component is identical, but silica, the total content of one or more in aluminium oxide or the carborundum is different, outer silica, the total content of one or more in aluminium oxide or the carborundum is than the height of internal layer parent, and in molar content, each constituent content concentration ratio internal layer parent of catalyst outer layer is low.

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

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

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 to get final product, as adopting following step preparation.

At first, Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, A among the Bi, the compound of Fe, Ni, Co and Si and general formula (I) _gB _hEach the elemental constituent compound that relates to dissolving and mix, carry out forming internal layer parent slurries after the co-precipitation, oven dry, moulding, roasting get the catalyst inner layer parent;

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

At last, the outer layer catalyst for preparing is coated on the catalyst inner layer parent successively, after roasting, gets finished catalyst.

Catalyst inner layer parent of the present invention is after the moulding and outer all need to compare not the respectively catalyst of roasting at 300～580 ℃ of lower roasting 3～10h after coating, and repeatedly roasting can improve the active and stable of catalyst.Can be that open roasting also can be enclosed roasting, calcination atmosphere can be the inert gases such as helium, nitrogen, argon gas.

Catalyst layer chaps during thick roasting very much easily, 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 the internal layer parent is 1.0～2.5mm, preferred 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 that when roasting, produces, and be not easy moulding, manufacturing schedule is slow, but nitrate is easy to dissolving, and nitrate preferably uses with other forms of compound, be easy to moulding, speed production efficient.

After the catalyst inner layer parent slurries of the present invention oven dry, the preferred forming methods such as extrusion molding, granulating and forming, compression molding that adopt are processed into spherical, hollow spheres, ellipticity, cylindric, hollow circuit cylinder etc., preferably hollow circuit cylinder or spherical usually.

Preferably use binding agent when multi-metal-oxide catalyst of the present invention applies, make ectonexine catalyst bonding more firm.Be under the rolling condition at the internal layer parent and spray binding agent and infiltrate the surface, the outer layer catalyst powder for preparing of spraying more also can be put into the internal layer parent outer layer catalyst slurries that the prepare coating of rolling.Binding agent is selected from one or more in water, alcohols or the ethers.Alcohols such as ethanol, propyl alcohol, butanols; Ethers such as ether and butyl ether.

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

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

The present invention has double-decker, and internal layer also can be called the internal layer parent.

Because catalyst initial reaction activity is very high, thus be easy to produce focus or produce heat localization at fixed bed single tube reactor bed, the easy sintering of catalyst, this loses concerning suitability for industrialized production methacrylaldehyde acrylic acid is very serious.Pass into a certain amount of steam in the raw material, because specific heat of water is large, can take away a large amount of reaction heat, make active decline but the 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 to exterior active combination of components substrate concentration internally, and catalyst outer layer active component concentration is lower than its internal layer active component concentration, like this, even under the high-speed reaction condition, because the active component concentration of catalyst outer surface is low, so corresponding activity is also low, therefore can emerging of establishment focus and gathering of heat, reduce the growing amount of accessory substance (such as hydrocarbon), improve the selective of purpose product.This has double-deck catalyst and has good water repelling property.And when catalyst runs after a period of time, catalyst has release effects, wash away lower at the mixed airflow long period, even the catalyst surface active component has part to run off, but because internal layer catalyst active component concentration is higher, can play additional effect, so can keep the 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 by general formula (i) with (ii) respectively from catalyst inner layer to outer chief component.

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

Mo _aBi _bFe _cNi _dSi _g (ii)

Wherein: Mo is molybdenum, and 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 that adds, and A is at least a element that is selected from strontium, potassium, titanium, the manganese; B is at least a element that is selected from zinc, tungsten, magnesium and the boron; O is oxygen; Si is silicon, silicon is the carrier that adds, a, b, c, d, e, f, g, m, n represents respectively each element atomic ratio, wherein when 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, and e is a number of 0.05～3, and f is a number of 0.05～5, g is a number of 0.5～20, m is a number of 0.05～3, and n is a number of 0.05～3, and x is the numerical value by the oxygen decision of each oxide, described compound multi-metal-oxide catalyst has double-decker, lanthanum and nickel, cobalts etc. can both form stable crystal phase structure, are conducive to suppress part active component molybdenum and lose because of distillation from catalyst surface, and active component molybdenum content is substantially constant before and after the catalyst reaction, 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 by general formula (i) with (ii) respectively from catalyst inner layer to outer chief component.

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

Mo _aBi _bFe _cCo _dSi _g (ii)

Wherein: Mo is molybdenum, and 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 that adds, and A is at least a element that is selected from alkali metal or the alkaline-earth metal; B is at least a element that is selected from zinc, cerium, the boron; O is oxygen; Si is silicon, and silicon is the carrier that adds, and a, b, c, d, e, f, g, m, n represent respectively each element atomic ratio, wherein when 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 by the oxygen decision of each oxide.

Catalyst granules with (III), (IV) expression successively reduces the part active component mutually from body to table, that is to say that catalyst has the active component of difference in functionality to the successively increase of body phase mutually by table, four kinds of components such as outer molybdenum except a main active function, bismuth, in activity inhibitor silicon and the aluminium one or both have only been added, active component is few, corresponding activity is also minimum, the unstripped gas of high concentration contacts with catalyst outer layer first, the moment reaction produces a large amount of heat, compares the 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, has dilution effect at the single catalyst particle, and the establishment focus emerges the heat localization that generates in a large number formation with byproduct of reaction.Have, even descend to some extent through catalyst outer surface activity after the some cycles running, also needn't unload catalyst, by simple activation process, internal layer catalyst body phase active material can play additional 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 the fixed bed single tube reactor; Reaction raw materials propylene, water, air enter reactor after the preheating through preheater more than 140 ℃, salt bath heating, and reaction process condition is: 290～345 ℃ of salt temperatures, preferred 300～335 ℃; Air speed 800～2400h ^-1, preferred 800～1600h ^-1, feed composition: propylene 7～14 volume %, air 68～74 volume %, steam 14～20%; Catalyst (III) or (IV) is housed in the 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 ℃.

The evaluating catalyst performance indications are defined as follows:

The molal quantity of propylene * 100% in the total mole number/raw material of propylene conversion (%)=propylene reaction

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

The specific embodiment

The below has the Catalysts and its preparation method of multilayer structure with specific embodiment explanation, and this catalyst produces the catalytic performance of methacrylaldehyde in the 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 gram ammonium molybdates and be dissolved in (water temperature is more than 65 ℃) in the 500ml pure water, obtain slurries (1), then get 40.7 the gram cobalt nitrates, 61.1 the gram nickel nitrates, 7 the gram potassium nitrate, 113 the gram ferric nitrates be dissolved in (water temperature is more than 65 ℃) in the 500ml pure water, fully mix, obtain slurries (2).Get again 237.7 gram 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 the slurries (4), obtain active component slurries (a).

(2) preparation of catalyst inner layer parent

In active component slurries (a), add 10.8 gram silica, 80 ℃ of strong stirrings carried out heat drying behind the coprecipitation reaction in 2 hours, in nitrogen with 160 ℃ of heat treatments 3 hours, then be the hollow columnar particle of φ 4.5 * 5mm through the banded extruder extrusion modling, dry rear 450 ℃ of roastings 4 hours for 75 ℃, 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 is outer

(1) preparation of active component slurries (a)

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

(2) preparation of catalyst outer layer

Active component slurries (a) and 23.6 gram silica powders are carried out coprecipitation reaction heat drying after 40 minutes, and with 150 ℃ of heat treatments 3 hours, then 500 ℃ of roastings were 4 hours in nitrogen, processed to get the catalyst outer layer powder through pulverizing, grind, sieving.

Step 3: Kaolinite Preparation of Catalyst 1

The catalyst inner layer parent of step 1 preparation is placed round bottom container, under container rotation condition, spray ethanolic solution to catalyst Precursors, under the condition of abundant wetting catalyst inner layer parent, stop operating, put it into rapidly in the round bottom container of the outer layer catalyst powder that is placed with step 2 gained of another rotation, apply, coating layer thickness is at 1.0～2.0mm, and 65 ℃ of oven dry of gained catalyst namely got catalyst 1 in 4 hours by 450 ℃ of roastings.

Comparative Examples 1:

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

Comparative Examples 2:

Take the skin of catalyst 1 as comparative catalyst 2, be the hollow columnar particle of φ 5 * 5mm through the banded extruder extrusion modling then, 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 gram ammonium molybdates and be dissolved in (water temperature is more than 65 ℃) in the 500ml pure water, obtain slurries (1), then get 30.6 the gram cobalt nitrates, 81.4 the gram nickel nitrates, 17.4 the gram ammonium phosphotungstates, 183.8 the gram ferric nitrates be dissolved in (water temperature is more than 65 ℃) in the 500ml pure water, fully mix, obtain slurries (2).Get again 169.8 gram 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 the slurries (4), obtain active component slurries (a).

(2) preparation of catalyst Precursors

In slurries (a), add 8.3 gram silica, 80 ℃ of strong stirrings carried out heat drying behind the coprecipitation reaction in 2 hours, in nitrogen with 160 ℃ of heat treatments 3 hours, then be the hollow columnar particle of φ 4.5 * 5mm through the banded extruder extrusion modling, dry rear 450 ℃ of roastings 4 hours for 95 ℃, make catalyst Precursors, this catalyst Precursors consists of: Mo ₁₄Bi ₅Co _1.5Fe _6.5Ni ₄W ₁

Step 2: Kaolinite Preparation of Catalyst is outer

(1) preparation of active component slurries (a)

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

(2) preparation of catalyst outer layer

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

Step 3: Kaolinite Preparation of Catalyst 2

The catalyst inner layer parent of step 1 preparation is placed round bottom container, under container rotation condition, spray ethanolic solution to catalyst Precursors, abundant 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 when 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 putting into the round bottom container that catalyst outer layer is housed continues to apply, until coating layer thickness stops to apply when 0.5～2.0mm, 125 ℃ of oven dry of gained catalyst namely got catalyst 2 in 3 hours by 500 ℃ of roastings.

Comparative Examples 3:

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

Comparative Examples 4:

Take the skin of catalyst 2 as comparative catalyst 4, be the hollow columnar particle of φ 4.5 * 5mm through the banded extruder extrusion modling then, 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 with embodiment 1 (following examples are also identical) adds 10.9 gram cesium nitrates, 26.1 gram ammonium metavanadates.

(2) preparation of catalyst inner layer parent

In slurries (a), add 15 gram silica, 80 ℃ of strong stirrings carried out heat drying behind the coprecipitation reaction in 2 hours, in nitrogen with 160 ℃ of heat treatments 3 hours, then be a granulated into the ball shape that diameter is 2mm through banded extruder extruding, rolling, dry rear 450 ℃ of roastings 4 hours for 105 ℃, 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 is outer

(1) preparation of active component slurries (a)

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

(2) preparation of catalyst outer layer

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

Step 3: Kaolinite Preparation of Catalyst 3

The catalyst inner layer parent of step 1 preparation is placed round bottom container, under container rotation condition, spray diethyl ether solution to catalyst Precursors, under the condition of abundant 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 is at 1.0～2.0mm, and 80 ℃ of oven dry of gained catalyst namely got catalyst 3 in 3 hours by 550 ℃ of roastings.

Comparative Examples 5:

Take 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 Examples 6:

Take 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 gram magnesium nitrates, 8.3 gram 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 is outer

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

Step 3: Kaolinite Preparation of Catalyst 4

The catalyst inner layer parent of step 1 preparation is placed round bottom container, under container rotation condition, spray ethanolic solution to catalyst, under the condition of abundant wetting catalyst inner layer parent, spray the outer layer catalyst powder of step 2 gained, apply, coating layer thickness is at 0.8～1.5mm, and 50 ℃ of oven dry of gained catalyst got catalyst 4 in 5 hours by 450 ℃ of roastings.

Comparative Examples 7:

Take 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 gram lanthanum nitrates, 7.3 gram silica, and this catalyst inner layer parent consists of: Mo ₁₂Bi ₉Co ₆Fe ₃Ni ₄K ₁La _0.2

Step 2: Kaolinite Preparation of Catalyst is outer

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

Step 4: apply time outer layer catalyst

The catalyst inner layer parent of step 1 preparation is placed round bottom container, under container rotation condition, spray distilled water to catalyst Precursors, under the condition of abundant 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, and 50 ℃ of oven dry of gained catalyst are for subsequent use by 500 ℃ of roastings 6 hours.

Step 5: Kaolinite Preparation of Catalyst 5

The catalyst of step 4 preparation is placed round bottom container, under container rotation condition, spray ethanolic solution to catalyst, under the condition of abundant wetting catalyst inner layer parent, spray the outermost layer catalyst fines of step 2 gained, apply, coating layer thickness is at 1.0～1.5mm, and 95 ℃ of oven dry of gained catalyst got catalyst 5 in 6 hours by 500 ℃ of roastings.

Comparative Examples 8:

Take 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 gram silica, outer 10 gram carborundum and the 15.6 gram silica of adding, and the 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 gram silica, outer 9 gram carborundum and the 15.6 gram silica of adding, and the catalyst inner layer parent consists of: Mo ₁₂Bi _4.5Co _2.5Fe _1.2Ni ₂Reaction condition is with the appreciation condition of catalyst 1.

Oxidation reaction

Fixed bed single tube reactor internal diameter 20mm, in establish thermocouple, the reactor feedstocks gas entrance side above-mentioned catalyst of 30ml of packing into, salt bath heating.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 establishment focus, catalyst reaction front and back active component molybdenum etc. does not run off substantially, after running in 1000 hours, active, selective kept stable.Comparative Examples 1～8 catalyst can not the establishment focus, and poor selectivity reacts behind 1000 hours rear catalysts that activity obviously descends under the washing away of the mixed airflows such as steam.

20 hours post-evaluation results of table 1 reaction

1000 hours post-evaluation results of table 2 reaction

Claims (10)

1. a multi-metal-oxide catalyst is characterized in that catalyst chief component such as general formula (I)

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

Wherein: Mo is molybdenum, and Bi is bismuth, and Fe is iron, and Ni is nickel, and Co is cobalt, and Si is silicon, and silicon is the carrier that adds in the catalyst, and A is at least a element that is selected from tellurium, niobium, boron, manganese, tungsten, the lanthanum; B is at least a element in selected among zirconium, vanadium, potassium, the 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, and f is a number of 0.5～55, and g is a number of 0～5, h is a number of 0～5, i is that described multi-metal-oxide catalyst has interior outer double-layer structure, outer silica by the numerical value of the oxygen decision of each oxide, the total content of one or more in aluminium oxide or the carborundum is than the height of internal layer parent, in molar content, each constituent content concentration ratio internal layer parent of catalyst outer layer 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 multilayer structure, and in molar content, outer each constituent content is than this constituent content of internal layer low 0.5～30%.

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

5. catalyst according to claim 1 is characterized in that A is lanthanum, and the composition of catalyst represents Mo with general formula (II) _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.

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

At first, Kaolinite Preparation of Catalyst internal layer parent:

To contain Mo, A among the Bi, the compound of Fe, Ni, Co and Si and general formula (I) _gB _hEach the elemental constituent compound that relates to dissolving and mix, carry out forming internal layer parent slurries after the co-precipitation, oven dry, moulding, roasting get the catalyst inner layer parent;

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

At last, the outer layer catalyst for preparing is coated on the catalyst inner layer parent successively, after roasting, gets finished catalyst.

7. the preparation method of catalyst according to claim 6, it is characterized in that the internal layer parent after the moulding and outer after coating at 300～580 ℃ of lower 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 using binding agent when described catalyst applies, and binding agent is selected from one or more in water, Ludox or the aluminium colloidal sol.

9. the preparation method of catalyst according to claim 6 is characterized in that binding agent is selected from one or more in alcohols or the ethers.

10. a multi-metal-oxide catalyst is characterized in that this catalyst has double-decker, represent by general formula (i) with (ii) respectively from catalyst inner layer to outer chief component,

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

Mo _aBi _bFe _cCo _dSi _g (ii)

Wherein: Mo is molybdenum, and 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 that adds, and A is at least a element that is selected from alkali metal or the alkaline-earth metal; B is at least a element that is selected from zinc, cerium, the boron; O is oxygen; Si is silicon, and silicon is the carrier that adds, and a, b, c, d, e, f, g, m, n represent respectively each element atomic ratio, wherein when 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 by the oxygen decision of each oxide.