US3321507A

US3321507A - Process for the production of unsaturated nitriles

Info

Publication number: US3321507A
Application number: US356045A
Authority: US
Inventors: Ginnasi Alessandro; Mauri Marcello Massi; Milanese San Donato; Colombi Antonio
Original assignee: Snam SpA
Current assignee: Snam SpA
Priority date: 1963-04-01
Filing date: 1964-03-31
Publication date: 1967-05-23
Anticipated expiration: 1984-05-23
Also published as: BE643909A; NL121947C; CH441287A; GB1065552A; NL294731A; LU45402A1; IT690486A; FR1382521A; CA759474A

Description

United States Patent 3,321,507 PROCESS FOR THE PRODUCTIQN 0F UNSATURATED NITRELES Alessandro Ginnasi, Milan, Marcello Massi Maori, San Donate Milanese, and Antonio Colombi, Milan, Italy, assignors to SNAM S.p.A., Milan, Italy, a company of Italy No Drawing. Filed Mar. 31, 1964, Ser. No. 356,045 Claims priority, application Italy, Apr. 1, 1963, 6,603/63, Patent 690,486 Claims. (Cl. 260-4653) It is an object of the present invention to provide a process of the preparation of unsaturated nitriles. More particularly the invention relates to the preparation of acrylonitrile from olefins, ammonia and oxygen, operating in the presence of catalysts.

The so-called ammoxydation reaction has been known for a long time, which takes place when an olefin is reacted in the gaseous phase, with oxygen or ammonia in the presence of suitable catalysts, obtaining nitrogen compounds which in suitable conditions are prevailingly unsaturated nitriles. Acrylonitrile is obtained by ammoxydation of propylene. As catalysts the literature indicates a vast range of metals from the End to the VIIth group of the periodic system or their compounds, for instance oxides or mixtures thereof. The known processes have not revealed so far the possibility of obtaining acrylonitrile starting from olefinic mixtures containing both propylene and butylenes, which however would be very convenient and advantageous.

It has now been found-and this forms the subject matter of the present inventionthat it is possible to obtain in a convenient and advantageous manner acrylonitrile while starting from hydrocarbon mixtures containing propylene as well as butylene. Such a process represents a considerable technical progress in that it makes possible conversion of propylene into acrylonitrile Without any or at any rate with only minimal cracking, whilst the contemporaneous conversion of the C instead requires that these be cracked in a controlled manner, in order to provide said unsaturated nitrile while excluding other nitriles undesirable for subsequent purifying operations.

It is apparent that the realization of a process wherein a component of the olefinic feed is not cracked, while the other components are cracked in a controlled manner, so that the C and C olefins all contribute to the acrylonitrile yield, constitutes an unexpected and surprising result not only with respect to the explicit teachings of the art, but also with respect to the expectations that could and had to be made in theory. In the process of the present invention hydrocarbon m'mtures containing propylene and butylenes are reacted in the gaseous phase, with oxygen and ammonia, in the presence of catalysts comprising molybdenum, vanadium and bismuth, wherein the active part contains from 0.5 to 3% by weight, and preferably from 1.3 to 1.8% of vanadium.

In a preferred embodiment of the invention, one operates with mixtures of olefins, oxygen, ammonia, in which the olefins are overall (C +C.,) in molar quantities smaller with respect to oxygen, and about equal or smaller with respect to ammonia.

The active part of the catalysts employed, which are conveniently supported, may be mixtures of oxides of molybdenum, vanadium and bismuth, or be other compounds or mixtures of compounds, in particular, the product of the calcination of a bismuth salt of a heteropolyacid of vanadium or molybdenum.

The ammonia-to-olefins ratio is not strictly critical. It is necessary at any rate that the ammonia should be fed at least in stoichiometric ratio to the overall quantity of olefins. There are no upper limits, if not dictated by economical factors since the excess ammonia is hardly recoverable. An upper practical limit can be indicated in the molar ratio NH /olefins=l.2. The oxygen should be fed in ratios to said overall quantity of olefins higher than 1 and preferably not higher than 2. It is advantageous that the oxygen should be fed with convenient diluents, such as nitrogen or carbon dioxide. In particular it is convenient to feed air.

It is preferable to conduct the reaction in the gaseous phase, in the presence of water, which can be fed in molar ratios even many times greater than 1, to the overall quantity of olefins such as for instance up to 20 moles of water per mole of olefins.

The time of contact is not critical, showing an optimum for durations shorter than 30 and preferably shorter than 10 seconds and equal at least to 0.5 second. The presence of saturated hydrocarbons in the feed does not cause any inconveniences.

The catalyst is generally supported on kieselguhr, celite or carborundum. In this case it can be prepared by mixing the active part with a support, kneading and then drying the whole. The solid mass obtained is ground to a convenient grain size and is then tabletted after previous addition of a suitable substance having the func tion of a binder.

The tabletted catalyst is charged into the reactor and is activated in situ by oxygen or air at 480 to 540 C., the optimum being shifted towards the temperatures closest to the upper limit.

A further advantage of the present invention is the absence of any danger in connection with the production of acrylonitrile, since no formation of acrolein has been noticed, the mixtures of which with air are notoriously explosive, or at any rate the formation of this aldehyde has always been below the explosive limits. It is obvious that it is possible to convert into nitriles, in the manner described in the present patent application, not only the mixtures of olefins but also the individual olefins that normally form part of the mixtures.

The invention will be more fully understood from the following non-limiting working examples.

EXAMPLE 1 2700 g. of Bi(NO -5H O, 1200 g. of ammonium molybdate and 70 g. of ammonium metavanadate, are calcined separately in a mufile at 450 to 500 C. and then mixed. A catalyst is obtained consisting of a mixture of oxides of vanadium, molybdenum and bismuth.

The active part so obtained is mixed with 1 kg. of celite, kneaded with water, extruded and reduced into pellets. The catalyst so prepared is charged, after drying, into the reactor constituted by a steel tube, and is activated in situ with air for 8 hours at 500 C.

If there is fed into the reactor, kept at 510 C., a propylene-ammonia-air-water mixture, respectively in molar ratios 1/1/7.5/15, at a space-velocity of 950 Nl./l. (of catalyst) hr., one gets a conversion into acrylonitnle of 54.2%, into acetonitrile of 3.5%, and into hydrocyanic acid of 8.5%, with a yield of useful products equal to 82%.

EXAMPLE 2 2700 g. of Bi(NO -5H O are dissolved in 300 ml, of nitric acid diluted with one liter of water. Another solution is prepared apart by dissolving 1200 g. of ammonium molybdate (81% of M00 and 70 g. of metavanadate of ammonium in 1 liter of water saturated with ammonia, then diluting the Whole with 1500 ml. of water. After having heated the two solutions up to C., the second solution is added to the first one, keeping the whole under stirring. A sludgy paste of brown colour is obtained which when cooled and washed with water and dried, shows on analysis the following results:

Percent by weight The remainder is oxygen.

The analysis of this product by X-rays shows the band of one single compound, the composition of which corresponds to a bismuth salt of a heteropolyacid of vanadium or molybdenum.

The active part so obtained is mixed with 1 kg. of kieselguhr and with water: the paste so prepared is extruded and reduced into pellets. These are dried and calcined in a muflle at 450 to 500 C. for 12 hours. One liter of the catalyst so prepared is charged into the same synthesis reactor of Example 1 and then activated by a stream of oxygen at 510 C. for 8 hours.

There is then fed to the reactor, kept at 510 C., a propylene-ammonia-air-water mixture, respectively with ratios (molar) 1/1/8/16, with a space velocity of 950 Nl./l./hr. One obtains conversions:

Percent Into acrylanitrile 70.4 Into acetonitrile 2.5 Into hydrocyanic acid 6.3

With a yield of useful product of 85.6%.

EXAMPLE 3 Over the catalyst of Example 2 a mixture of butene-2, ammonia, air and water in a molar ratio, respectively, of 1/1/6/20 is passed at a velocity of about 1000 Nl./l./hr., While varying the temperature, obtaining the results tabu- Under the same conditions of Example 3 butene-l is used instead of butene-2, obtaining the results of the following table:

Conversion, percent Temperature Yield of use- O. in] prod.,

Acrylonitrile Acetonitrile HON percent EXAMPLE 5 The synthesis of acrylonitrile is carried out on the catalyst of Example 2, from ammonia, air and a refinery gas having the following composition:

Percent molar c rr crr 1.3 0,11 17.5 C3H8 21.1 iso-C 11 c u 8.2 04H, 33.3

The volumetric ratios in the feed between refinery gas, ammonia, air and water are 1/ 1/ 3.5/20.

41 Operating at a space velocity of 983 Nl./1/hr., at 515 C., the following molar conversions with respect to the unsaturated C and C compounds are obtained:

Percent Conversion into acrylonitrile 48.5 Concersion into acetonitrile 14.2 Conversion into hydrocyanic acid 20.8

The yield of useful products is 79% (again calculated with respect to the unsaturated compounds).

EXAMPLE 6 Under identical conditions as Example 5, there is effected the synthesis of acrylonitrile from ammonia, air, water and a refinery gas having the following composition:

Percent molar The following molar conversions with respect to the unsaturated C and 0., compounds are obtained:

Percent Conversion into acrylonitrile 4.35 Conversion into acetonitrile 15.6 Conversion into hydrocyanic acid 15.8 Yield of useful products 86 EXAMPLE 7 The synthesis of acrylonitrile is eifected under the same conditions as in Example 5, feeding a refinery gas diluted in unsaturated products. The analysis of said gas is as follows:

Percent molar c rn+c r1 3.7 c n, 11.8 c n 28.9 iso-C H C4H8 15.2 C4H10 27.9

The conversions with respect to the unsaturated C and C compounds are:

Percent Conversion into acrylonitrile 42.3 Conversion into acetonitrile 15.9 Conversion into hydrocyanic acid 14.2 Yield of useful products The embodiments of the invention in which an exizlusive property or privilege is claimed are defined as folows:

1. A process for the production of acrylonitrile in which a refinery gas consisting essentially of C H +C H in a molar ratio range of 0.6% to 3.7%, of C H in a molar ratio range of 11.8% to 22.1%, of C H in a molar range of 19.2% to 28.9%, of iso C H in a molar range of 12.5% to 18.6%, of C H in a molar ratio range of 8.2% to 20.1% and of C H in a molar ratio range of 22.7% to 33.3%, the sum total of said components in the gas being essentially is reacted with ammonia and oxygen in the presence of an oxidation catalyst consisting essentially of a mixture of bismuth oxide, molybdenum oxide, and vanadium oxide, where the vanadium content is between 0.5 and 3%, the reaction being conducted at a temperature between 450 C. and 525 C. and for from 0.5 to 30 seconds.

2. A process for making acrylonitrile as claimed in claim 1, wherein the total molar quantities of the olefins is less than the molar quantity of the oxygen used in the reaction.

3. A process for making acrylonitrile as claimed in claim 1, wherein the total molar quantities of the olefins are no greater than the molar quantity of ammonia used in the reaction.

4. A process for making acrylonitrile as claimed in claim 1, wherein the reaction is carried out in the gaseous phase in the presence of Water.

5. A process for making acrylonitrile as claimed in claim 1, wherein the reaction time is less than ten seconds.

References Cited by the Examiner UNITED STATES PATENTS Derwent, Belgium R 6 Minekawa et a1. 260-4563 McDaniel et a1. 260-4563 X Callahan et a1. 260-456. X Giordano et a1. 260-4563 Yasuhara et al 260-4563 OTHER REFERENCES eport No. 66A, p. A23, July 15,

CHARLES B. PARKER, Primary Examiner.

JOSEPH P. BRUST, Examiner.

Claims

1. A PROCESS FOR THE PRODUCTION OF ACRYLONITRILE IN WHICH A REFINERY GAS CONSISTING ESSENTIALLY OF C2H4+C2H6 IN A MOLAR RATIO RANGE OF 0.6% TO 3.7%, OF C3H6 IN A MOLAR RATIO RANGE OF 11.8% TO 22.1%, OF C3H8 IN A MOLAR RANGE OF 19.2% TO 28.9%, OF ISO C4H8 IN A MOLAR RANGE OF 12.5% TO 18.6%, OF C4H8 IN A MOLAR RATIO RANGE OF 8.2% TO 20.1% AND OF C4H10 IN A MOLAR RATIO RANGE OF 22.7% TO 33.3%, THE SUM TOTAL OF SAID COMPONENTS IN THE GAS BEING ESSENTIALLY 100%, IS REACTED WITH AMMONIA AND OXYGEN IN THE PRESENCE OF AN OXIDATION CATALYST COSISTING ESSENTIALLY OF A MIXTURE OF ISMUTH OXIDE, MOLYBDENUM OXIDE, AND VANADIUM OXIDE, WHERE THE VANADIUM CONTENT IS BETWEEN 3.5 AND 3%, THE REACTION BEING CONDUCTED AT A TEMPERATURE BETWEEN 450%C. AND 525%C. AND FOR FROM 0.5 TO 30 SECONDS.