JP4462403B2 - Ammoxidation catalyst replacement method - Google Patents

Description

  The present invention relates to a method for replacing a catalyst in a reactor when propylene, ammonia and molecular oxygen are subjected to an ammoxidation reaction in the presence of a catalyst in a fluidized bed reactor to produce acrylonitrile.

  A method for producing acrylonitrile by a so-called ammoxidation reaction, which is a reaction of propylene, ammonia and molecular oxygen, is well known, and many catalysts used for this ammoxidation reaction have been proposed. As a catalyst used in the ammoxidation reaction, an oxide catalyst containing molybdenum, bismuth and iron is disclosed in Patent Document 1, and an oxide catalyst containing antimony and iron is disclosed in Patent Document 2, and these catalyst systems are Improvements are continuing from various viewpoints.

  Regarding the improvement of oxide catalysts containing molybdenum, bismuth and iron, Patent Document 3 discloses a catalyst containing one or more elements selected from potassium, rubidium and cesium in addition to molybdenum, bismuth and iron. In addition to Patent Document 4, a catalyst containing one or more elements selected from rare earth elements such as cerium, lanthanum, neodymium, and praseodymium similarly contains one or more elements selected from palladium, platinum, osmium, and iridium. A catalyst is disclosed in US Pat.

  Patent Document 6 discloses a catalyst containing one or more elements selected from nickel and cobalt in addition to molybdenum, bismuth and iron, and further including one or more elements selected from alkali metals, rare earth elements, tantalum and niobium. In addition to molybdenum, bismuth, cerium, iron, cobalt, a catalyst containing one or more elements selected from potassium, rubidium, and cesium is disclosed in Patent Document 7, in addition to molybdenum, bismuth, cerium, iron, nickel, A catalyst containing at least one element selected from potassium, rubidium and cesium is disclosed in Patent Document 8 as a catalyst containing at least one element selected from potassium and cesium in addition to molybdenum, bismuth, iron, nickel and magnesium. It is disclosed in Patent Document 9.

  Further, with respect to the improvement of an oxide catalyst containing antimony and iron, a catalyst obtained by firing with antimony and at least one metal element selected from iron, cobalt, nickel, manganese, uranium, tin and copper as essential components A catalyst produced by impregnating and firing at least one metal compound selected from molybdenum, vanadium and tungsten and a tellurium compound is disclosed in Patent Document 10 as vanadium, molybdenum, tungsten, iron, antimony, tellurium as essential components. A catalyst characterized in that tellurium is dissolved in an iron-antimony oxide compound includes Patent Document 11 containing at least one element selected from iron, tin, and uranium with antimony, tellurium, and palladium as essential components. The catalyst is made of iron, antimony and phosphorus as essential in Patent Document 12. Catalyst comprising bets as a crystal phase is disclosed in JP 13 - iron Anchimone as.

  However, in order to introduce these developed catalysts into industrial-scale reactors, a total amount replacement method in which all of the catalyst in the reactor used so far is extracted and the developed catalyst is introduced into the reactor. Is common. For this reason, in addition to the need for a large amount of catalyst temporarily, a large amount of waste catalyst is generated at the same time.

Japanese Patent Publication No. 38-17967 Japanese Examined Patent Publication No. 38-19111 Japanese Patent Publication No.58-2232 Japanese Examined Patent Publication No. 61-26419 Japanese Examined Patent Publication No. 61-58462 Japanese Patent Publication No.51-33888 Japanese Patent No. 3214975 Japanese Patent No. 3214984 Japanese Patent No. 3337696 Japanese Examined Patent Publication No. 52-42552 Japanese Examined Patent Publication No. 53-18014 Japanese Patent No. 2582860 Japanese Patent No. 2950851

  The present invention seeks to provide an efficient method for introducing newly improved catalysts into industrial scale reactors, and more particularly, newly developed catalysts. An object of the present invention is to provide an effective catalyst replacement method that does not require a large amount of catalyst temporarily and does not generate a large amount of waste catalyst at the same time when replacing the catalyst with the catalyst in the reactor. It is.

As a result of intensive studies, the present inventors have found that the present invention having the following configuration can solve the above problems.
(1) In the replacement method of ammoxidation catalyst in the fluidized bed reactor propylene and ammonia and molecular oxygen by ammoxidation in the presence of a catalyst for producing acrylonitrile, substituted catalysts with improved to be substituted catalysts and new An oxide catalyst supported on silica, which is represented by the following empirical formula (1) or (2), under the following condition (1), using a fixed bed reactor, Conducting an oxidation reaction to measure the conversion rate of propylene, the activity of the displacement catalyst at the same temperature calculated as the primary reaction of propylene from this conversion rate is in the range of 1/2 to 2 times the activity of the catalyst to be substituted, A method for replacing an ammoxidation catalyst, wherein the replacement ratio of the replacement catalyst to the replacement catalyst is in the range of 0.1 to 1.0 kg / T-AN.
Empirical formula _{(1): Mo 12 Bi a} Fe b C c D d E e F f G g O x
(C is one or more elements selected from Ni, Co, Mn, Zn, Mg, Ca, Sr and Ba, D is one or more elements selected from rare earth elements, E is Cr, W, B, Al , Ga, In, P, Sb and Te, one or more elements selected from F, F is one or more elements selected from Pd, Rh, Ru, Pt, Ir and Os, G is Na, K, Rb and Cs 1 or more elements selected from O, O represents oxygen, a is 0.05-8, b is 0.5-8, c is 0-12, d is 0-5, e is 0-5, f Is 0 to 1, g is 0.01 to 2, and x is the number of oxygen atoms necessary to satisfy the valence requirements of other elements present.)
Experimental formula (2): Sb ₁₀ H _h J _j K _k O _y
(H is one or more elements selected from Fe, Co, Ni, Co, Mn, U, Ce, Sn and Cu, J is one or more elements selected from V, Mo and W, K is Mg, Ca, Sr, Ba, La, Ti, Zr, Nb, Ta, Cr, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Zn, Cd, B, Al, Ga, In, Tl, Ge, One or more elements selected from Pb, P, As, Bi, Se and Te, O represents oxygen, h is 1 to 10, j is 0 to 5, k is 0 to 10, and y is another (This is the number of oxygen atoms required to satisfy the element valence requirements.)
Condition (1): Using a SUS316 reaction tube having an inner diameter of 10 mm, the reaction temperature is selected from the range of 420 to 470 ° C., the pressure is atmospheric pressure, the catalyst amount is 1 g, and the gas composition to be supplied is propylene: ammonia: oxygen Water: helium = 1: 1.2: 1.89: 1.85: 12.58 The amount of gas to be supplied is 2.4 NL / Hr.

(2) The activity of the substitution catalyst is in the range of 1/2 to 2 times the activity of the catalyst to be substituted, and the substitution ratio of the substitution catalyst to the catalyst to be substituted is 0.2 to 0.8 kg / T-AN. (1) The method for replacing an ammoxidation catalyst.
(3) The activity of the substitution catalyst is in the range of 1 / 1.5 to 1.5 times the activity of the catalyst to be substituted, and the substitution ratio of the substitution catalyst to the catalyst to be substituted is 0.3 to 0.6 kg / T-AN. The method for replacing an ammoxidation catalyst according to the above (1), which is carried out in the range of 1.

  According to the method of the present invention, when an acrylonitrile is produced from propylene, ammonia and molecular oxygen by an ammoxidation reaction, different types of catalysts can be efficiently replaced in an industrial scale reactor.

  The substituted catalyst and the substitution catalyst of the present invention are oxide catalysts supported on silica and are represented by the following empirical formula (1) or empirical formula (2).

Empirical formula _{(1): Mo 12 Bi a} Fe b C c D d E e F f G g O x
(C is one or more elements selected from Ni, Co, Mn, Zn, Mg, Ca, Sr and Ba, D is one or more elements selected from rare earth elements, E is Cr, W, B, Al , Ga, In, P, Sb and Te, one or more elements selected from F, F is one or more elements selected from Pd, Rh, Ru, Pt, Ir and Os, G is Na, K, Rb and Cs 1 or more elements selected from O, O represents oxygen, a is 0.05-8, b is 0.5-8, c is 0-12, d is 0-5, e is 0-5, f Is 0 to 1, g is 0.01 to 2, and x is the number of oxygen atoms necessary to satisfy the valence requirements of other elements present.)

Experimental formula (2): Sb ₁₀ H _h J _j K _k O _y
(H is one or more elements selected from Fe, Co, Ni, Co, Mn, U, Ce, Sn and Cu, J is one or more elements selected from V, Mo and W, K is Mg, Ca, Sr, Ba, La, Ti, Zr, Nb, Ta, Cr, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Zn, Cd, B, Al, Ga, In, Tl, Ge, One or more elements selected from Pb, P, As, Bi, Se and Te, O represents oxygen, h is 1 to 10, j is 0 to 5, k is 0 to 10, and y is another (This is the number of oxygen atoms required to satisfy the element valence requirements.)

  Therefore, there are four combinations of the catalyst to be replaced and the replacement catalyst: Mo catalyst and Mo catalyst, Mo catalyst and Sb catalyst, Sb catalyst and Mo catalyst, Sb catalyst and Sb catalyst, A combination of Mo-based catalyst and Mo-based catalyst, Sb-based catalyst and Sb-based catalyst is preferable, and a combination of Mo-based catalyst and Mo-based catalyst is more preferable.

  The silica content of the substituted catalyst and the substituted catalyst is such that the ratio of the weight of silica to the total weight of the silica and the oxide catalyst is 30 to 70% by weight, preferably 40 to 60% by weight.

Moreover, the preferable experimental formula (3) of the substituted catalyst and the replacement catalyst in the experimental formula (1) is as shown below.
Empirical formula _{(3): Mo 12 Bi a} Fe b C c D d E e F f G g O x
(C is one or more elements selected from Ni, Co, Mg and Zn, D is one or more elements selected from Y, La, Ce, Pr, Nd and Sm, E is Cr, Ga, In and One or more elements selected from P, F is one or more elements selected from Pd, Rh, Ru, Pt, Ir and Os, G is one or more elements selected from K, Rb and Cs, a is 0.1 to 6, b is 0.5 to 7, c is 0 to 12, d is 0 to 4, e is 0 to 4, f is 0 to 0.5, g is 0.01 to 1, and x is (This is the number of oxygen atoms necessary to satisfy the valence requirements of other elements present.)

A more preferred empirical formula (4) of the substituted catalyst and the substituted catalyst is as shown below.
Empirical formula _{(4): Mo 12 Bi a} Fe b C c D d G g O x
(C is one or more elements selected from Ni, Co and Mg, D is one or more elements selected from La, Ce, Pr and Nd, particularly preferably Ce, and d / (a + d) = 0. .6 to 0.8, a + d = 0.5 to 2, b is 0.5 to 3, c is 4 to 10, g is 0.01 to 1, G is one or more selected from K, Rb, and Cs And x is the number of oxygen atoms necessary to satisfy the valence requirements of other elements present.)

The activity of the substituted catalyst and the substituted catalyst is measured under the condition (1) using a fixed bed reactor, and the value is obtained as the primary reaction of propylene. Specifically, when the conversion rate of propylene is z%, the activity is represented by the formula (1).
Formula (1): Activity = ln [1 / [1- (z / 100)]]

  In the present invention, as the relationship between the activity of the substituted catalyst and the substituted catalyst measured at the same reaction temperature, the activity of the substituted catalyst needs to be in the range of 1/3 to 3 times the activity of the substituted catalyst. Preferably, the activity of the substitution catalyst is in the range of 1/2 to 2 times the activity of the substituted catalyst. More preferably, the activity of the substitution catalyst is in the range of 1 / 1.5 to 1.5 times the activity of the substituted catalyst.

  When the activity of the substitution catalyst is less than 1/3 of the activity of the catalyst to be substituted, the amount of the catalyst after substitution is about 3 times, and a large amount of substitution catalyst is required to maintain the production amount, which is not preferable. In addition, when the activity of the displacement catalyst exceeds 3 times the activity of the catalyst to be replaced, the amount of the catalyst after the substitution is about 1/3, and heat removal in the fluidized bed reactor is not performed efficiently due to the reduction of the amount of catalyst. , It becomes difficult to continue the reaction.

  The substitution ratio of the substitution catalyst to the substitution catalyst is in the range of 0.1 to 1.0 kg / T-AN. Further, it is preferably carried out in the range of 0.2 to 0.8 kg / T-AN, more preferably in the range of 0.3 to 0.6 kg / T-AN. This substitution ratio is defined as the amount of catalyst relative to the weight of acrylonitrile (AN) produced. Therefore, in a reactor that produces 100,000 T acrylonitrile annually, when this substitution rate is 0.5 kg / T-AN, 50 T catalyst can be introduced into the reactor.

When the substitution ratio of the substitution catalyst to the substitution catalyst is less than 0.1 kg / T-AN, the substitution takes too many years and is not efficient. In addition, when the replacement ratio of the replacement catalyst to the replacement catalyst exceeds 1.0 kg / T-AN, a waste catalyst corresponding to the replacement ratio is generated in a short period of time, which is largely different from replacing the entire amount at once. The effect of this method cannot be obtained because there is no.
The surface area of the catalyst is a measure of the catalyst activity, and the surface area of the substituted catalyst is preferably in the range of 0.5 to 2.0 times the surface area of the substituted catalyst.

  The catalyst of the present invention can be prepared by a method described in patent literature. For example, taking an Mo-based catalyst as an example, a first step of preparing a raw material slurry, a second step of drying the raw material slurry, and a third step of firing the dried product obtained in the second step Can be obtained by a method comprising

  In the first step, a catalyst raw material is prepared to obtain a raw material slurry. Molybdenum, bismuth, iron, nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, barium, chromium, tungsten, boron, aluminum, gallium, Sources of elements such as indium, rare earth elements, phosphorus, sodium, potassium, rubidium and cesium include ammonium salts, nitrates, hydrochlorides, sulfates, organic acid salts, inorganic acids, etc. that are soluble in water or nitric acid. Can be mentioned.

  In particular, as an element source of each element of molybdenum and tungsten, ammonium salts are bismuth, iron, nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, barium, chromium, aluminum, gallium, indium, rare earth elements, sodium, potassium As the element source of each element of rubidium and cesium, respective nitrates are preferable.

  For the preparation of the raw slurry, if the catalyst contains phosphorus, phosphoric acid is added to the silica sol, then ammonium salts such as molybdenum and tungsten dissolved in water are added to the silica sol, and then bismuth, iron, nickel Nitric acid salts of elemental elements such as cobalt, manganese, zinc, magnesium, calcium, strontium, barium, chromium, aluminum, gallium, indium, rare earth elements, sodium, potassium, rubidium and cesium are dissolved in water or aqueous nitric acid. This can be done by adding a fresh solution. In this way, a raw slurry can be prepared. At that time, the order of the addition can be changed.

  In the second step, the raw material slurry obtained in the first step is spray-dried to obtain substantially spherical particles. The atomization of the raw material slurry can be performed by a method such as a centrifugal method, a two-fluid nozzle method, and a high-pressure nozzle method which are usually carried out industrially. Next, the obtained particles are dried, and it is preferable to use air heated by steam, an electric heater or the like as a drying heat source. The temperature at the dryer inlet is 100 to 400 ° C, preferably 150 to 300 ° C.

  In the third step, the desired catalyst composition is obtained by calcining the dried particles obtained in the second step. The dried particles are calcined as necessary at 150 to 450 ° C. and then at 450 to 750 ° C., preferably 500 to 700 ° C. for 1 to 20 hours. Firing can be performed using a firing furnace such as a rotary furnace, a tunnel furnace, or a muffle furnace. The catalyst composition of the present invention is preferably distributed in the range of 10 to 150 μm as the particle size.

Similarly, the Sb-based catalyst can be prepared by the method described in the patent literature.
Propylene and ammonia, which are raw materials for the ammoxidation reaction, do not necessarily have high purity, and industrial grade ones can be used. As the molecular oxygen source, it is usually preferable to use air, but a gas whose oxygen concentration is increased by mixing oxygen with air can also be used.

  As the composition of the raw material gas, the molar ratio of ammonia to air with respect to propylene is propylene / ammonia / air = 1 / 0.8 to 1.4 / 7 to 12, preferably 1 / 0.9 to 1.3 / 8 to 11 range. The reaction temperature is 420 to 470 ° C, preferably 430 to 460 ° C. The reaction pressure can be carried out in the range of slightly reduced pressure to 0.3 MPa. The contact time between the raw material gas and the catalyst is 0.5 to 20 (sec · g / cc), preferably 1 to 10 (sec · g / cc).

  Hereinafter, the present invention will be described in detail with reference to examples. In the examples, the conversion rate and the acrylonitrile yield used to express the reaction results are defined by the following equations.

Conversion rate (%)
= [(Mole number of propylene reacted) / (Mole number of propylene fed)] × 100
Acrylonitrile yield (%)
= [(Mole number of acrylonitrile produced) / (Mole number of supplied propylene)] × 100

The catalyst composition supported on 50% by weight of silica described in Example 1 of Japanese Patent No. 3214984 is Mo ₁₂ Bi _0.20 Ce _0.40 Fe _2.0 Ni _5.6 Mg _2.2 K _0.07. An oxide catalyst represented by Cs _0.04 was prepared according to the method described in the specification. The activity of this catalyst measured at 440 ° C. was 13.4 (1 / Hr), and the surface area was 63.7 m ² / g. The obtained catalyst 29T was charged into a fluidized bed reactor, the reaction temperature was 440 ° C., the propylene flow rate was 1250 Nm ³ / Hr, the propylene / ammonia / air molar ratio = 1 / 1.13 / 9.0, and the reaction pressure was 0.16 MPa. As a result of operating under the conditions, the propylene conversion was 99.1% and the acrylonitrile yield was 80.7%.

Next, the catalyst composition supported on 50% by weight of silica described in Example 2 of the same publication is Mo ₁₂ Bi _0.45 Ce _0.90 Fe _1.8 Ni _5.0 Mg _2.0 K _{0. An} oxide catalyst represented by _0.09 Rb _0.05 was prepared according to the method described in the specification. The activity of this catalyst measured at 440 ° C. was 10.4 (1 / Hr), and the surface area was 50.3 m ² / g.

This catalyst was introduced into the reactor at a substitution rate of 0.5 kg / T-AN and operated for 3 years. The total amount of catalyst added to the reactor within this period was 31.5 T, and it was almost possible to replace it with a new catalyst. The operating conditions after the substitution were as follows: the reaction temperature was 440 ° C., the propylene flow rate was 1250 Nm ³ / Hr, the propylene / ammonia / air molar ratio = 1 / 1.13 / 8.9, and the reaction pressure was 0.16 MPa. The conversion was 99.0% and the acrylonitrile yield was 82.0%.

  The catalyst replacement method of the present invention is a fluidized bed reactor in which propylene, ammonia and molecular oxygen are subjected to an ammoxidation reaction in the presence of a catalyst to produce acrylonitrile. A newly developed catalyst is used as a catalyst in the reactor. It can be used as a method for efficient replacement.

Claims (3)

In the method for replacing an ammoxidation catalyst in a fluidized bed reactor in which propylene, ammonia and molecular oxygen are subjected to an ammoxidation reaction in the presence of the catalyst to produce acrylonitrile, the catalyst to be replaced and the newly improved replacement catalyst are supported on silica. The oxide catalyst is expressed by the following empirical formula (1) or (2), and propylene ammoxidation reaction is carried out using a fixed bed reactor under the following condition (1). And the conversion rate of propylene is measured, and the activity of the substitution catalyst at the same temperature calculated from the conversion rate as the primary reaction of propylene is in the range of 1/2 to 2 times the activity of the substitution catalyst. A method for replacing an ammoxidation catalyst, wherein the replacement ratio of the replacement catalyst to the catalyst is 0.1 to 1.0 kg / T-AN.
Empirical formula _{(1): Mo 12 Bi a} Fe b C c D d E e F f G g O x
(C is one or more elements selected from Ni, Co, Mn, Zn, Mg, Ca, Sr and Ba, D is one or more elements selected from rare earth elements, E is Cr, W, B, Al , Ga, In, P, Sb and Te, one or more elements selected from F, F is one or more elements selected from Pd, Rh, Ru, Pt, Ir and Os, G is Na, K, Rb and Cs 1 or more elements selected from O, O represents oxygen, a is 0.05-8, b is 0.5-8, c is 0-12, d is 0-5, e is 0-5, f Is 0 to 1, g is 0.01 to 2, and x is the number of oxygen atoms necessary to satisfy the valence requirements of other elements present.)
Experimental formula (2): Sb ₁₀ H _h J _j K _k O _y
(H is one or more elements selected from Fe, Co, Ni, Co, Mn, U, Ce, Sn and Cu, J is one or more elements selected from V, Mo and W, K is Mg, Ca, Sr, Ba, La, Ti, Zr, Nb, Ta, Cr, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Zn, Cd, B, Al, Ga, In, Tl, Ge, One or more elements selected from Pb, P, As, Bi, Se and Te, O represents oxygen, h is 1 to 10, j is 0 to 5, k is 0 to 10, and y is another (This is the number of oxygen atoms required to satisfy the element valence requirements.)
Condition (1): Using a SUS316 reaction tube having an inner diameter of 10 mm, the reaction temperature is selected from the range of 420 to 470 ° C., the pressure is atmospheric pressure, the catalyst amount is 1 g, and the gas composition to be supplied is propylene: ammonia: oxygen Water: helium = 1: 1.2: 1.89: 1.85: 12.58 The amount of gas to be supplied is 2.4 NL / Hr.   The activity of the substitution catalyst is in the range of 1/2 to 2 times the activity of the catalyst to be substituted, and the substitution ratio of the substitution catalyst to the catalyst to be substituted is 0.2 to 0.8 kg / T-AN. The method for replacing an ammoxidation catalyst according to claim 1. The activity of the substitution catalyst is in the range of 1 / 1.5 to 1.5 times the activity of the catalyst to be substituted, and the substitution ratio of the substitution catalyst to the catalyst to be substituted is in the range of 0.3 to 0.6 kg / T-AN. The method for replacing an ammoxidation catalyst according to claim 1, wherein the method is carried out.