JPS5846055A - Preparation of methacrylonitrile - Google Patents

Abstract

PURPOSE:To increase the yield of the titled compound, by feeding the recovered methacrolein formed as a by-product into the reaction system, and bringing isobutylene or tert-butanol into contact with ammonia and oxygen in the vapor phase at a high temperature in the presence of a catalyst. CONSTITUTION:Isobutylene or tert-butanol is brought into contact with ammonia and oxygen in the vapor phase at a high temperature in the presence of a catalyst, e.g. the formula[A is Ni or CO; B is Na, K, etc.; C is P, As, etc.; D is Cr, Mn, etc.; (a)-(f) are the ratios of the elementary components based on Mo12; (x) is the number of oxygen atoms satisfying the valence of the metals]to give methacrylonitrile. In the process, the methacrolein formed as a by-product is recovered and refed into the reaction system. The refed methacrolein is almost completely converted into methacrylonitrile, CO2, CO, etc., and the conversion into the methacrylonitrile is generally higher than that from the isobutylene or tert-butanol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves recovering methacrolein as a by-product when producing methacrylonitrile by contacting imbutylene t or tertiary-getanol with ammonia and oxygen in the presence of a catalyst in a gas phase at high temperatures. This invention relates to a method for increasing the yield of methacrylonitrile by ammoxidizing methacrolein at the same time as isobutylene or tertiary-butanol.

It is known to produce methacrylonitrile by contacting isobutylene or tertiary ttanol with ammonia and oxygen in the presence of a catalyst in the gas phase at high temperature. - to about 101 methacrolein is produced as a by-product. The present invention makes it possible to efficiently increase the production of methacrylonitrile by recovering this by-product methacrolein, supplying it again to the reaction system, and ammoxidizing the methacrolein simultaneously with isobutylene or tertiary-butanol. be.

According to the present invention, when methacrolein is supplied into the ammoxidation reaction system of inbutylene or tert-butanol, the supplied methacrolein is almost completely converted into methacrolein.
The concentration of methacrolein at the outlet of the reactor is almost the same between when methacrolein is supplied and when it is not supplied. Therefore, even if methacrolein is recycled, there is no difference in the concentration of methacrolein in the system. In addition, since the conversion rate of methacrolein to methacrylonitrile is generally higher than that of isobutylene or tertiary tutanol to methacrylonitrile, the by-product methacrolein is not accumulated. The effect of increasing the yield of methacrylonitrile by recycling is considerably large.

In the present invention, isobutylene or tertiary-ffi/
- Even if methacrolein is supplied to the ammoxidation reaction system, it is not recognized that the catalyst will be poisoned or that methacrolein will cause a side reaction with nitriles etc. to produce undesirable by-products.・Another advantage of the main production IjlIO% is that 9 methacrolein produced as a by-product in the reactor is generally separated from methacrylonitrile by distillation, but the boiling point of methacrolein (70.1°C) and the boiling point of methacrylonitrile are the same. (90.3°C) d A large amount of energy is required to completely separate the rounds that are relatively close to each other, but using the present @O method, methacrolein containing methacrylonitrile can be placed in a reactor. Since it can also be recycled, the energy costs associated with distillation can be significantly reduced.

At this time, methacrolein can be converted into methacrylonitrile in a high yield, although methacrylonitrile is not substantially changed in the reactor and flows out of the reactor again.

The catalyst used in the present invention can be any catalyst that is active in the ammoxidation reaction of inbutylene or tertiary-butanol, but particularly preferred examples include Mo, F.-1bAeBdC, Df
O! (In the formula, A is at least one element selected from Nl and Co, B is Na, K, Rb and (j
At least one element selected from s, C is P, A
At least one element selected from s and B (boron), D is at least one element selected from Cr, Mn, Mgt8b, and subscripts a and b.

cede・ and f are the elemental components F・, Bi, A, B, C and Do atomic ratios to Na12 atoms, respectively, a-0~10, b=0.1-7, @=θ~10
, d-0~2, ・=0~5, the value of f-0~'5 is 69,
Preferably *=1-8 m b"0.3-61・=
θ~8.4W0.01~1.・=value of 0 to 4, X
is the number of oxygen atoms satisfying the valence of the metal in the catalyst) and 8b. -A, -B, -C, -Dd-Ox [The person in the formula is F
・, U, at least 1m element selected from anO, at least 11i element selected from B id Mo , W, V, C is TI * P e B
At least one element selected from (boron), D
is Cut Mgt Ca, sr, Ba, Az,
Cr, Mn, CotNi, B1. C., La
, at least one element selected from TI, with subscript I Hb 14! 1 d e X are each S
b. Elemental components A, B, C for atoms.

The atomic ratio of D and O is a=1~20 m b=0~3
Q, @WO~10s d=0~10, more preferably a=2~10, b==o, o
1-5°.WO11-5, (the value of lzQ~5, where l is the number of oxygen atoms satisfying the valence of the metal in the catalyst) is rejected.

Particular examples of representative catalyst compositions are as follows.

1) Mo, 2Bi, P.

2) Mgt2 Ba4.6F@a, 9KO,s P1
3) Mo4. B145 F@45') ”'1! ”1.9 ”4.40O5, I KO
,4Pl5) Na12 B11F@! S C02,5
N12.5 KO, I Po, 56) Mo1. B1
9F@2P, 8b27) “1!”4J”7.2
KOJ Pl, 2') ”12 ”0.45 ”14
”7.50rOJ KO, S Po, 15s) M0
12ms4.5"4.5 Na14 KO, I Pll
o) “12 B14.6”4.0 RbO,,pl
ll) Work 12 ”4.5 ”4.5 ”1.2 KO,
I B2 PO, 512) Na12 Bi, Pl1
,5 Ni, Mn, KO,2PoJ13) Mo1
2B11F@1,5 Nl, M12KO12POJ1
4) Sb,, Horse,,0x 15) Sb1. U, WO,, TI (1,2oxl
s) 8b,. 8Big 0x 17) 8b, oan20Ti, °X 18) 8b, 08iI20CJ (1,5oxls)
sb,. 8n, 6 TI2 Cu, Ox20) 5b1
0 S! 14 Wo, 2 T@OJ Q! 21) 8b
,. F・20x 22) 8b,. F@sV, T., 0823) 8b
,. F・6M04TI, 0x24) 8b10F@4v
'l001T@g, 4ox25) 8b, OF@2Mo
2 vo, oz T@g, 4 ”0.126) 5b1
6 Fe2 yb6jWO,, T@OJ 0x27)
8b. F@, &1), 4 Wo,, T・I Cu
, 0!28) 5b10 F@I MOOJ Wo,
, T・t Cu, Ni1 ozThe catalyst used in the present invention can be a catalyst having the composition described in ItII alone, but in view of the strength of the catalyst, it is generally selected from silica, alumina, borate, pumice, etc. It is used by supporting it on any carrier.

There is no particular restriction on the amount of catalyst component Om supported on the body, but generally it is 10 to 9011 amount -I! based on the total weight of the catalyst. Hold it for a while.

The catalyst used in the present invention converts isobutylene and tertiary-butanol into methacrylonitrile with high selectivity, while also converting methacrolein, which is simultaneously supplied into the reaction system, into methacrylonitrile with high selectivity. It is. Therefore, by supplying methacrolein into the main reaction system of the ammoxidation reaction of isobutylene or tertiary-citanol, it is possible to increase the production of methacrylonitrile. In this case, the ratio of methacrolein to isobutylene or tertiary ttanol is not particularly limited and can be arbitrarily selected.

Isozothyre yt'#:, a When methacrylonitrile is produced by ammoxidation of tert-butanol, methacrolein is usually produced as a by-product in an amount of about 10%.
According to the method of the present invention, this by-product methacrolein is recovered and recycled to the reactor again, and the by-product methacrolein is effectively utilized to effectively produce the desired methacryl tetranitrile.

In this case, the recovered methacrolein does not need to be highly purified and can be returned to the main reaction system as crude methacrolein containing other nitriles, water, etc., which is extremely advantageous in industrial implementation. . The position at which methacrolein is supplied to the reactor can be arbitrarily selected, but it is preferably at the same position as inbutylene or tertiary-butanol or at a downstream position.

The reaction according to the present invention can be carried out in either a fixed bed or a fluidized bed.The reaction temperature is generally in the range of 300 to 550°C, preferably 350 to 500°C. The reaction pressure can be normal pressure, but the reaction can be carried out under reduced pressure or increased pressure, if necessary.

The molar ratio of isobutylene (or tertiary citanol), ammonia, and oxygen in the reaction system is generally 1:0.
．． 8-5:1-5, preferably 1:1-2:2-3. Further, the amount of ammonia and oxygen to be supplied corresponding to the methacrolein supply lid may be appropriately determined on the basis of approximately 0.5 to 1.5 moles of ammonia and 1 to 3 moles of oxygen per 1 mole of methacrolein.

In the case of the catalyst used in the present invention, it is not particularly necessary to add water vapor and/or inert gas, but water vapor and/or inert gas can be added if necessary.

The contact time between the raw material mixed gas and the catalyst is generally 0.3~
15 seconds, preferably in the range of 0.5 to 10 seconds.

The present invention will be described in detail below, but it goes without saying that the scope of the present invention is not limited to these Examples.

Catalyst Preparation Example 1 Me, 21F・7j B14.5 KOJ Pl, 20
A 50 weight-supported catalyst on silica having a composition x was prepared as follows.

Take 5000j' of silica sol (Snowtex N manufactured by Yasan Kagaku) containing 30wt StO□, add 61.2g of 35wt phosphoric acid to it while stirring, and then add 7-morisory# ammonium to 2400Jl of water. [(N
Add a solution of H4-5Mo70□4-4H20] 948j, and finally add 92111 (11(N
o, ), -5H203,1293NO ferric nitrate [F.
(No, ), 9H20], and a mixed solution containing 13.6 jl of potassium nitrate (KNO, ) were added. The raw material slurry obtained here is sent to a parallel flow type spray dryer and dried.9.The raw material slurry is atomized using a centrifugal type atomizer equipped with a dish-shaped rotor installed in the center of the upper part of the dryer. It was done using The obtained dry powder was calcined in a tunnel kiln at 690° C. for 2 hours to obtain a catalyst. This will be referred to as catalyst 1.

Catalyst Preparation Example 2 A catalyst having a composition of Mo, 2F64.5''4.50x and supported at 50% by weight on silica was prepared in the same manner as in Catalyst Preparation Example 1.
shall be.

Catalyst Preparation Example 3 By the same method as in Catalyst Preparation Example 1, Mo,,F・4.4 "1.9"5.1 KO,4P
A catalyst was prepared in which 50% by weight of a composition of 10X was supported on a resilica. However, as a Co source, cobalt nitrate (Co
(NO, ) , 6H20) was added to the dissolved mixture of bismuth nitrate, ferric nitrate, and potassium nitrate.

Further, the catalyst was fired at 700°C for 2 hours. This is catalyst 3
shall be.

Catalyst Preparation Example 4 Me, 2Bi,
F*, CO2,5N1. ,,Ko,,P,50x
A catalyst having the composition of 501 silica supported on silica was prepared. However, cobalt nitrate (Co
(NOx)2 ”6H20], Nissoji, Kel (Nt(N
O,)2.6H20] was added to the dissolved mixture of bismuth nitrate, ferric nitrate, and potassium nitrate. Further, the catalyst was calcined at 650° C. for 2 hours. This is called touch 1s4.

Catalyst Preparation Example 5 8b according to the method 9 described in Example 6 of Japanese Patent Publication No. 40-24367. A catalyst having a composition of U, ..., Ox and having 40vt9G supported on silica was prepared from N. This is referred to as Catalyst 5. Catalyst Preparation Example 6 Sb according to the method described in Example 6 of British Patent Publication No. 904,602. A catalyst with a composition of 5n4oOx was prepared. This will be referred to as catalyst 6.

Catalyst Preparation Example 7 sb according to the method described in Example 9 of Japanese Patent Publication No. 49-20180. A catalyst having a composition of F.4.5T@2M010x and having 50vt Ti supported on silica was prepared.

However, the catalyst is fired at 700℃ using a tunnel kiln.
I went to the Gin Seki. Pf this! Let it be A medium 7.

Catalyst Preparation Example 8 Sb, , Fe3Mo according to Catalyst Preparation Example 7. ,5W,,
A catalyst having a composition of To, Cu, and OK and supported at 50% by weight on silica was prepared. This will be referred to as catalyst 8.

Example 1 Each of the catalysts prepared in Catalyst Preparation Examples 1 to 8 above had an inner diameter of 8
wm (D, filled into a glass reaction tube, and
The temperature is maintained at 10 to 450°C, and a mixed gas containing isobutylene, tert-getanol, methacrolein, ammonia, and ridges adjusted to a predetermined molar ratio is added with helium until the amount of isobutylene + tert-butanol reaches 6 volumes. It was diluted and passed at a speed that gave a contact time of 1.0 to 3.0 seconds. The reaction pressure at this time was atmospheric pressure. Table 1 shows the test results of this ammonia-rich reaction.

Comparing the cases where methacrolein is allowed to coexist in the raw material mixed gas and the case where methacrolein is not made to coexist in each catalyst, an increase in methacrylonitrile is clearly observed when methacrolein is made to coexist in both cases.

Furthermore, when the reactor outlet gas is analyzed and the amount of methacrolein produced is examined, the value is almost the same regardless of whether methacrolein is supplied or not. This means that approximately 100 methacrolein was converted to methacrylonitrile and others.

In addition, no phenomenon of catalyst poisoning and deactivation during the reaction in which methacrolein was supplied was observed in any of the catalysts, and there were no by-products produced when methacrolein was not supplied, especially when methacrolein was supplied. No new by-products have been detected.

Margin below Example 2 Simultaneous ammoxidation test of methacrolein and isobutylene 16 mesh of catalyst 120011 on the back side 1 of the catalyst tone.

Methacrolein, imbutylene, ammonia and air were charged into a fluidized bed reactor with a diameter of 3 inches and equipped with a stainless wire mesh, and the reaction temperature was maintained at 430°C and the reaction pressure was maintained at 0.2 ky/cm'' gauge pressure. The ammoxidation reaction was carried out by changing the volume ratio of .

However, the total amount of mixed gas was adjusted to 420j/hour in terms of NTP.

The test results of this ammoxidation reaction are shown in Table 2.

Experiment number l is the case where methacrolein does not coexist, and To
Methacrylonitrile O from isobutylene 1 moj
-74m@j is found to be produced, and assuming that the production rate of methacrylonitrile from isobutylene does not change even if methacrolein coexists, in experiment numbers 2 to 4, methacrolein from methacrolein The conversion rate was 82 to 85. Experiment No. 5 was a case in which tertiary butylene was supplied instead of inbutylene, and it can be seen that there is no difference from that in the case of isobutylene.

In addition, the test results after the reaction was continued for 20 days under experiment number 20 conditions showed that the amount of methacrolein produced was 0.052 mo.
l/H, and the amount of methacrylonitrile produced is 1.14
3 mot/H, and there was no difference from the initial results. Blank space below Example 3 Each of the catalysts from Catalyst Preparation Examples 1 and 3.4 was filled into a glass reaction tube with an inner diameter of 8 cm, and kept at 410 to 430°C.
In this, inbutylene, ammonia, and oxygen are added in a molar ratio of 1.
: Simultaneous ammoxidation test of methacrolein and imbutylene or tertiary-butanol with a gas mixed in a ratio of 1.6 : 2.5 with helium until the imbutylene content is 6'4 it % ( 2)
Recovered methacrolein (methacrylonitrile pure [70%, acrylonitrile 15%, acetone trile 1.5%, acetone 2 -, methacrinitrile (10%), hydrocyanic acid (O, S*, etc.) were simultaneously supplied at a concentration of 10 mol per inbutylene. At this time, the contact time was 1 to 2.0 seconds, and the reaction pressure was atmospheric pressure. The test results are shown in Table-3.

In any of the catalysts, no phenomenon was observed where the catalyst was poisoned or deactivated during the reaction in which recovered methacrolein was supplied.
In addition, no new by-products were detected in 41% of cases when methacrolein was supplied, other than those produced when methacrolein was not supplied.

The following margin procedural amendment (voluntary) October 9, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki-dono 1, Indication of the case 1982 Patent Application No. 142368 2, Title of invention Process for producing methacrylonitrile 3, Amendment Relationship with the case of a person who does the following: Patent applicant name (003) Asahi Kasei Kogyo Co., Ltd. 4, Agent address: Shizuko Toranomon Building, 8-10 Toranomon-chome, Minato-ku, Tokyo "Detailed description of the invention" section of the specification 6. Contents of amendment 1) Page 16, line 10 of the specification, r420 lJ to r4
7 (Correct to IJ.

2) Correct all numerical values "10" of the air tanks of experiment numbers 1 to 5 in Table 2 on page 18 to '11.5J.

that's all

Claims (1)

[Claims] 1. In a method for producing methacrylonitrile by contacting isobutylene or tertiary-butanol with ammonia and oxygen in the presence of a catalyst in the gas phase at high temperature, methacrolein as a by-product is recovered and fed back into the reaction system to produce imbutylene. Alternatively, a method for producing methacryloetrile, which increases the yield of methacrylonitrile by ammoxidizing methacrolein simultaneously with tertiary-butanol.