Vinyl cyanide is important Organic Chemicals, and it is produced by the ammoxidation of propylene reaction.For obtaining the fluid catalyst of high reactivity, highly selective, people have carried out a series of improvement through constantly exploring.These improve and mostly relate to catalyst activity partly, pay attention to the collocation between the catalyst activity component, and improve activity of such catalysts and selectivity, thereby reach the raising of vinyl cyanide once through yield, and the raising of producing load.
Oxidation proceses of ammonia is produced vinyl cyanide through 30 years of development, and the throughput of factory and the market requirement are near balance.The main development tendency of acrylonitrile process has been turned to the transformation of original factory, further to cut down the consumption of raw materials and to increase throughput by the construction new device at present.By transformation to original factory, change the bottleneck in effective catalyst and the elimination production technique, the throughput of vinyl cyanide might improve 50~80%, and required investment only is 20~30% of a new device, economic benefit is very huge.
Can produce two problems during factory transforms: 1. the reaction pressure of fluidized-bed reactor will rise; 2. the loading capacity of catalyzer can not be too many.The catalyzer that for this reason requires to use instead should have higher propylene load and can bear higher reaction pressure.
The reaction pressure of fluidized-bed reactor is to be determined to the resistance drop that absorbs a series of interchanger, tower and pipe arrangement the cat head by reactor outlet.Because the increase of throughput obviously increases the inventory of reactor outlet, above-mentioned resistance drop is increased.In addition, each heat exchanger heat transfer area also need increase heat-exchange equipment inadequately, and resistance drop is further increased.Because environmental requirement, the reactor off-gas that absorbs cat head is forbidden directly to be discharged in the atmosphere, deliver to stove and burn.If like this without induced draft fan, then must improve the absorption tower top pressure.For all the foregoing reasons, the working pressure of reactor will increase by 0.5~1.0 times than design load at present, promptly reaches more than the 0.08MPa.
Above-mentioned second load that problem is a catalyzer, i.e. WWH.Its definition is a catalyzer per ton, per hour can handle what ton propylene.Because the increase of reactor feed amount, if the load of catalyzer is constant, then the catalyzer loading capacity is also wanted corresponding increase.But water-cooled tube insufficient height in the intrinsic fluidized-bed reactor, so the fluid height of catalyst reactor might surpass the height of water-cooled tube.In addition, because the increase of reactor feed amount, so operating linear velocity also significantly improves.The combined influence of these two variations might make reactor dilute phase temperature rise, and causes carbon dioxide production to increase, and the vinyl cyanide selectivity descends.Therefore the WWH of catalyzer is higher can prevent the problems referred to above.
The WWH that improves catalyzer in theory should increase the adsorptive power of catalyzer to propylene, but at present still in the catalyst-free certain element can improve theory to the propylene adsorptive power.The catalyzer of following composition has been proposed in document CN1021638C:
A
aB
bC
cNi
dCo
eNa
fFe
gBi
hM
iMo
jO
x
Wherein A is potassium, rubidium, caesium, samarium, thallium; B is manganese, magnesium, strontium, calcium, barium, lanthanum, rare earth element; C is phosphorus, arsenic, boron, antimony, chromium; M is tungsten, vanadium.
Above-mentioned catalyzer can obtain higher single-pass yield of acrylonitrile, but the propylene of catalyzer load is lower, and single-pass yield of acrylonitrile descends bigger under higher reaction pressure.Studies show that further the B component in the above-mentioned catalyzer is relevant with performance under high pressure to the load of catalyzer with M.Though some element in the B component has effect to improving single-pass yield of acrylonitrile, and the raising of catalyst loading and the performance of high-response pressure are had negative impact, be unfavorable for that catalyzer adapts to elevated pressures, operates under the higher load condition.Once in stipulating in CN1021638C in addition that above-mentioned catalyzer was formed, the summation of i and j is 12, promptly is a constant.Cancel this regulation in the present invention,, will influence single-pass yield of acrylonitrile because molybdenum component will reduce when increasing by this regulation M component.
Introduced the technology that a kind of catalyzer that uses basic metal, molybdenum, bismuth, cerium and tungsten system carries out preparing acrylonitrile by allylamine oxidation in the document US 4746753.Find out that from embodiment its catalyst system is not contain sodium, though mention metallic element praseodymium (Pr) in the optional elements, only use as optional elements.Do not disclose the collocation service condition of praseodymium and W elements among the embodiment, and do not mention reaction pressure concrete in the experimental implementation and operational load situation data.
Introduced a kind of manufacture method of vinyl cyanide among the flat 8-27089 of document.It adopts the catalyzer of molybdenum, bismuth, iron, magnesium and tungsten system to carry out the ammoxidation of propylene reaction, and the investigation condition among the document embodiment is a normal pressure, does not mention the situation data under high pressure, high operational load condition.
The objective of the invention is to overcome the catalyzer that exists in the above-mentioned document and can not adapt to problem, a kind of fluid catalyst of new production vinyl cyanide is provided than high-response pressure and operational load.This catalyzer can adapt under higher reaction pressure and higher loading condiction to be operated, and keeps high vinyl cyanide once through yield.
The objective of the invention is to realize by following technical scheme: a kind of fluid catalyst of producing vinyl cyanide, form by silica supports with the following composition of atomic ratio measuring chemical formula:
Mo
12Bi
aFe
bW
cPr
dNa
eX
fY
gZ
hO
i
X is selected among P, As, B, Ge, Ga, Al, Sn, Pb, Cr, V, Nb or the Tb at least a in the formula;
Y is selected among Co, Ni, Mn, Mg, Ca, Sr, Zn or the Cd at least a;
Z is selected among K, Rb, Cs, In, Tl, Sm or the Te at least a.
The span of a is 0.01~3.0;
The span of b is 0.1~5.0;
The span of c is 0.01~2.0;
The span of d is 0.01~2.0;
The span of e is 0.05~0.7;
The span of f is 0.01~3.0;
The span of g is 0.10~12.0;
The span of h is 0.01~1.5;
I satisfies the required Sauerstoffatom sum of each element valence in the catalyzer;
Wherein the amount of carrier silicon-dioxide is 30~70% by weight percentage in the catalyzer.
The value preferable range of d is 0.01~1.0 in the technique scheme, the value preferable range of c is 0.05~1.5, and the value preferable range of e is 0.1~0.5, and the value preferable range of f is 0.01~2.0, the value preferable range of g is 0.1~10.0, and the value preferable range of h is 0.05~1.0.The amount of silicon-dioxide is 40~60% by weight percentage in the catalyzer.
The manufacture method of catalyzer of the present invention there is no particular requirement, can be undertaken by well-established law.At first the catalyzer each component is made solution, be mixed and made into slurry with carrier again, the spray-dried microspheroidal that is shaped to, catalyzer is made in last roasting.The preparation of slurry is preferably undertaken by the CN1005248C method.
The raw material of making catalyzer of the present invention is:
Molybdenum component in the catalyzer is with molybdenum oxide or ammonium molybdate.
The most handy corresponding acids of phosphorus in the catalyzer, arsenic and boron or its ammonium salt; Tungsten can be with ammonium tungstate or Tungsten oxide 99.999; Its oxide compound of germanium; The vanadium ammonium meta-vanadate; The most handy chromium trioxide of chromium, chromium nitrate or the mixture of the two; The most handy its nitrate of all the other components, oxyhydroxide maybe can be decomposed into the salt of oxide compound.
Raw material available silicon colloidal sol, silicon gel or both mixtures as carrier silicon-dioxide.If use silicon sol, its quality will meet the requirement of CN1005248C.
It is 47~55% back spraying dryings that the prepared slurry heating is concentrated to solid content.Spray-dryer available pressure formula, two streamings or centrifugal turntable formula, but, can guarantee that the catalyzer of making has good size-grade distribution with centrifugal better.
The roasting of catalyzer can be divided into two stages and carry out: each element decomposition of salts and high-temperature roasting in the catalyzer.The catabolic phase temperature is preferably 200~300 ℃, and the time is 0.5~2 hour.Maturing temperature is 500~800 ℃, is preferably 550~700 ℃; Roasting time is 20 minutes to 2 hours.Above-mentioned decomposition and roasting are carried out respectively in two stoving ovens, also can be divided into two zones in a stove, also can finish simultaneously in the continous way rotary roasting furnace and decompose and roasting.In catalyst decomposes and roasting process, to feed an amount of air, prevent that catalyzer is by over reduction.
Adopt the specification of catalyzer manufacturing vinyl cyanide of the present invention required propylene, ammonia and molecular oxygen identical with other ammoxidation catalyst of use.Though the low molecule saturated hydrocarbon content in the raw material propylene to the reaction did not influence, considers that from economic point of view density of propylene is more preferably greater than 85% (mole).Ammonia can be used fertilizer grade liquefied ammonia.Reaction desired molecule oxygen can be used pure oxygen from technical standpoint, oxygen enrichment and air, but from economy and the most handy air of security consideration.
Entering the ammonia of fluidized-bed reactor and the mol ratio of propylene is between 0.8~1.5, is preferably 1.0~1.3.The mol ratio of air and propylene is 8~10.5, is preferably 9.0~9.8.If owing to some operational reason must with higher air than the time, can increase to 11, reaction is not had great effect.But from security consideration, the excess of oxygen in the reactant gases can not preferably be not more than 4% greater than 7% (volume).
When catalyzer of the present invention was used for fluidized-bed reactor, temperature of reaction was 420~470 ℃, was preferably 430~450 ℃.Therefore catalyzer of the present invention is a kind of high pressure, high loading catalyzer of being applicable to, reaction pressure can be more than 0.08MPa in production equipment, for example, and 0.08~0.15MPa.Also do not have any disadvantageous effect if reaction pressure is lower than 0.08MPa, single-pass yield of acrylonitrile can further improve.
The propylene load (WWH) of catalyzer of the present invention is 0.06~0.15 hour
-1, be preferably 0.07~0.10 hour
-1Loading to hang down not only wastes catalyzer, and carbon dioxide production is increased, and selectivity descends, and is disadvantageous.Loading does not too highly have practical significance, because the catalyzer add-on is very few, the heat transfer area that can make catalyst layer internal cooling water pipe causes temperature of reaction uncontrollable less than removing the required area of reaction heat.
The product of making vinyl cyanide with catalyzer of the present invention reclaims process for refining, and available existing production technique need not done any transformation.The eluting gas that is fluidized-bed reactor is removed unreacted ammonia through neutralizing tower, with water at low temperature whole organic products is absorbed again.Absorption liquid is through extractive distillation, dehydrogenation cyanic acid and dewater high-purity propylene nitrile product.
Because the tungsten in the component is favourable to improving load, praseodymium can improve the performance of catalyzer at high-response pressure, therefore remove some have negative impact to high pressure, high loading reactivity worth component, increase the usage quantity of tungsten, and tungsten, praseodymium uses simultaneously, and catalyzer has been had in that (WWH is 0.090 hour than high-response pressure (0.14MPa), higher load
-1) operational capability under the condition, and the vinyl cyanide once through yield has been up to 82% level, obtained effect preferably.
Activity of such catalysts of the present invention examination is to carry out in internal diameter is 38 millimeters fluidized-bed reactor.Loaded catalyst 550g, 440 ℃ of temperature of reaction, reaction pressure 0.14MPa, proportioning raw materials (mole) is a propylene: ammonia: air=1: 1.2: 9.8, the propylene load (WWH) of catalyzer is 0.090 hour
-1
Propylene conversion, vinyl cyanide selectivity and once through yield are defined as follows in the present invention:
The invention will be further elaborated below by embodiment.[embodiment 1]
With 0.72 gram cesium nitrate, 4.8 gram SODIUMNITRATE and 2.43 gram saltpetre mixing, add water 30 grams, the dissolving of heating back gets material (A); 18.67 gram chromium trioxides are dissolved in the 8.4 gram water, get material (B); It is in 5% the ammoniacal liquor that 19.4 gram ammonium tungstates are dissolved in 100 milliliters of weight concentrations, 395.2 gram ammonium molybdates are dissolved in 50~90 ℃ of hot water of 325 grams, with two solution mix material (C); Restrain Bismuth trinitrates, 4.91 with 90.4 and restrain niobium oxides, 2.45 gram praseodymium nitrates, 434 gram nickelous nitrates and 150.8 gram iron nitrates mixing, add water 70 and restrain, the dissolving of heating back gets material (D).
With material (A) and 1250 gram weight concentration is that 40% silicon sol mixes, under agitation add material (B) and (C) and (D), fully stir slurry, by well-established law the slurry of making is shaped to framboid in spray-dryer, it is 89 millimeters at internal diameter at last, length be in the rotary roasting furnace of 1700 millimeters (89 * 1700 millimeters of φ) in 630 ℃ of roastings 1 hour, the catalyzer of making consists of: 50%Mo
12Bi
1.0Fe
2.0W
0.45Pr
0.05Na
0.3Ni
8.0Cr
1.0Nb
0.2K
0.13Cs
0.02O
1+ 50%SiO
2[embodiment 2~9 and comparative example 1~4]
Adopt method preparation substantially the same manner as Example 1 to have the different catalyzer of forming in the following table, and, the results are shown in Table 1 with carrying out the reaction that ammoxidation of propylene generates vinyl cyanide under the prepared catalyzer reaction conditions below.
The reaction conditions of the foregoing description and comparative example is:
38 millimeters fluidized-bed reactors of φ
440 ℃ of temperature of reaction
Reaction pressure 0.14MPa
Loaded catalyst 550g
Catalyzer propylene load (WWH) 0.090 hour
-1
Proportioning raw materials (mole) C
3 =/ NH
3/ air=1/1.2/9.8
Table 1
Embodiment | Catalyzer is formed | Acrylonitrile yield % |
Embodiment 1 | Mo
12Bi
1.0Fe
2.0W
0.45Pr
0.05Na
0.3Ni
8.0Cr
1.0Nb
0.2K
0.13Cs
0.02O
i | 80.3 |
Embodiment 2 | Mo
12Bi
1.0Fe
2.0W
0.45Pr
0.1Na
0.3Ni
8.0Cr
0.5Ga
0.5K
0.05Cs
0.05Tl
0.05O
i | 81.4 |
Embodiment 3 | Mo
12Bi
1.0Fe
2.0W
0.75Pr
0.2Na
0.3Ni
8.0Ge
0.05Al
0.5Cs
0.15Tl
0.05O
i | 80.0 |
Embodiment 4 | Mo
12Bi
1.0Fe
2.0W
0.75Pr
0.25Na
0.3Ni
6.0Mn
2.0Ge
0.1Nb
0.1Cr
1.0K
0.08Cs
0.12O
i | 79.9 |
Embodiment 5 | Mo
12Bi
1.0Fe
2.0W
1.0Pr
0.75Na
0.3Ni
6.0Mn
2.0Ga
0.1Cr
0.75Ge
0.5K
0.1Cs
0.05Tl
0.15O
i | 81.9 |
Embodiment 6 | Mo
12Bi
1.0Fe
2.0W
0.75Pr
0.15Na
0.3Ni
8.0Cr
0.5Ge
0.08K
0.15Rb
0.08Tl
0.12O
i | 80.7 |
Embodiment 7 | Mo
12Bi
1.0Fe
2.0W
0.45Pr
0.2Na
0.3Ni
8.0Nb
0.1Cr
0.8Ge
0.2Rb
0.05Cs
0.15Tl
0.05O
i | 79.5 |
Embodiment 8 | Mo
12Bi
1.0Fe
2.0W
0.45Pr
0.5Na
0.3Ni
6.0Ca
2.0Cr
0.5Ge
0.5K
0.08Cs
0.05Tl
0.15O
i | 82.0 |
Embodiment 9 | Mo
12Bi
1.0Fe
2.0W
0.1Pr
0.1Na
0.3Ni
6.0Ca
2.0Cr
0.8Ga
0.1K
0.1Rb
0.05Cs
0.03O
i | 80.5 |
Comparative example 1 | Mo
12Bi
0.9Fe
1.8Ni
2.0Co
5.0Na
0.15Mn
0.45Cr
0.45K
0.17Cs
0.05O
i | 76.8 |
Comparative example 2 | Mo
12Bi
0.9Fe
1.8Ni
2.0Co
5.0Na
0.15Mn
0.45Cr
0.45K
0.21O
i | 76.2 |
Comparative example 3 | Mo
12Bi
0.9Fe
1.8Ni
2.4Co
4.3Na
0.15W
0.45Cr
0.45K
0.15Cs
0.07O
i | 77.1 |
Comparative example 4 | Mo
12Bi
0.9Fe
1.8Ni
5.0Mg
2.0Na
0.15W
0.45Cr
0.45Cs
0.09O
i | 77.4 |