FI61682C - FRAMSTAELLNING AV AKRYL- ELLER METACRYLSYRA AV PROPYLEN ELLER ISOBUTYLEN I ETT EN-REAKTORVIRVELBAEDDSYSTEM - Google Patents

Description

ΠΓ «^ · Ί ΓβΙ / h ^ ANNOUNCEMENT PUBLICATION ^ 1 / Cn0

JggA LBJ 11 UTL & GGN I NGSSKRI FT 6 1 ° 0 * C M5 \ 3 exam ri} · ".r ,; tty 10 09 1932

Patent Medium ^ ^ ^ (51) Kv.lk?/Int.CI.3 C 07 C 57/04 SUOM I —FI N LAN D (21) P * Mnttlh «k.imi · - Ptt« icii «eicni» g 12 months / 7b (22) Hikamltptivi - Anseknlngsdag 2 * +. OH. 7 * + (23) Start - GlttlghMsdig 2U.01.71 * (41) Tullut | external - Bllvlt offtntllg 31.10.7 * +

National Board of Patents and Registration (44) NthUvUlilpvwn,. moonUJulk, Liun p¥ m._

Patent-och registerstyrelsen 'Aniökan utitgd och uti.skrift «n pubiicsrad 31 3 5.72 (32) (33) (31) Pyydetty stuoiktus —Begird prlorltst 30. OU. 73 USA (US) 35561 * 8 (71) The Standard Oil Company, Midland Building, Cleveland 15, Ohio, USA (US) (72) Arthur Francis Miller, Lyndhurst, Ohio, Robert Karl Grasselli, Chagrin Falls, Ohio, David Byerly Terrill, Bedford, Ohio, USA (US) (7I +) Oy Kolster Ab (5I *) Process for the preparation of acrylic or methacrylic acid from propylene or isobutylene in a single-reactor fluidized bed system torvirvelbäddsystem

Oxidation of propylene or isobutylene has been performed in two solid-batch reactors containing two different catalysts for best yield. Combining the two catalysts in one reactor has not been considered appropriate because the other catalyst acts on the olefin to form by-products. In this case, before the desired reaction takes place, undesirable by-products are formed in place of the desired unsaturated acids.

Several catalysts are known which are effective in the conversion of propylene or isobutylene. Representative patents for wedding catalysts include: U.S. Pat. 2 9 ^ 1 007; 3,248 3 ^ 0; 3,639,269; 3,362,998; 3,629 1U8; 3,576,764; 3,171,859; Dutch 769,689; Belgian 767,659; 77 ** 905 and 777 ** 76, which introduce bismuth molybdate and other molybdate catalysts; US 3,428 6? 4 ^ 3 * + 31 292; 3 5 * + 2 81 + 2; 3 5 * + * + 616; and 3,551 1 * 70, which show various uranium catalysts effective in the preparation of unsaturated aldehydes from propylene and isobutylene; other catalysts effective in this oxidation of olefins are disclosed in the following patents: U.S. Pat. No. 3,226 * 4,225; 3,197 * + 19; 3,200 08l; 3,282,982; 3,468,958; 3,408 UOO; Dutch 7OI809I; British 1,091 96l.

2 61 682

Catalysts used as other catalysts in the invention are also known. Representative other catalysts for use in accordance with the invention are disclosed in U.S. Pat. Nos. 3,567,773; 3,567,772; Belgian 773,851; Dutch 7205593; Canadian 8931 * + 5; Belgian 77 * + 329; German 2 217 77 * + and German 2 21 * + * + 80, which show the oxidation of unsaturated aldehyde oxidation catalysts using catalysts containing at least molybdenum. Other catalysts for the preparation of acids are disclosed in U.S. Pat. No. 2,881,11 * +; 2,811,213; 2,811,212; 3,395,178; German 2 0 * i6 * ill; Japanese 72/11909 and Belgian 78U 263.

When performing exothermic reactions in fixed bed reactors, temperature control presents difficulties. Such difficulties do not occur in a fluidized bed reactor because heat transfer takes place easily therein and thus an optimum temperature is obtained in all parts of the reactor.

The mixing of the catalyst and the reacting gases in the fluidized bed reactor is also clearly better than in the fixed bed reactors, which results in a better yield.

One advantage of using both catalysts in a single reactor is also the cost savings obtained when only one reactor is needed.

The use of two catalysts in a single fluidized bed reactor to oxidize olefins to an acid has not been previously described. Also, the highly advantageous yields of acrylic acid and methacrylic acid obtainable in the present invention have not been expected in the art.

According to the present invention, it has now been found that the preparation of acrylic acid and methacrylic acid by reacting propylene or isobutylene with molecular oxygen in the presence of an oxidation catalyst can be improved by a) carrying out the reaction in a fluidized bed reactor as an oxidation catalyst, a catalyst containing two different catalysts - the first catalyst being particularly effective in oxidizing propylene or isobutylene to acrolein or methacrolein and the second catalyst being particularly effective in oxidizing acrolein or methacrolein to acrylic acid or methacrylic acid. Surprisingly, the use of the process according to the invention achieves a high conversion into usable acid products per feed, while avoiding the costs of two separate reactors previously used in the art.

As mentioned above, the present invention is a process for preparing acrylic acid or methacrylic acid from propylene or isobutylene using process conditions, reactant feeds and reaction parameters previously used in the art. The idea of the present invention is the use of a fluidized bed reactor as well as the use of an oxidation catalyst containing two different catalysts.

Fluidized bed reactors suitable for use in the present invention are well known. In general, these reactors comprise a charge of finely divided particles of oxidation catalyst that expands under the action of reactants flowing through the catalyst. In a preferred embodiment of the invention, the oxidation catalyst in the fluidized bed reactor has a particle size of less than about 300 micrometers; and when using the reactor, the volume of the charge formed by the oxidation catalyst is about 5 to 50 a larger than the volume of the unexpanded charge.

As a fluidized bed reactor, in principle, any reactor of a structure compatible with the process according to the invention can be used. One basic requirement is that a substantially undivided reaction space be formed in the fluidized bed reactor. In the reaction state, the reactants form the desired products in the presence of an oxidation catalyst. An important feature of this reaction space is that the oxidation catalyst of the invention can move throughout the reaction space. Naturally, in the actual design of a fluidized bed reactor, there are areas where the movement of the oxidation catalyst is considerably stronger than in other parts; therefore, the invention is not limited by the requirement for uniform movement of all catalyst particles throughout the charge. Instead, it is limited by the fact that in the normal operation of the fluidized bed reactor, the oxidation catalyst particles are able to reach each point in the reaction space.

The fluidized bed reactor used in the invention may be an open batch reactor with little or no restriction on the flow of the oxidation catalyst, or the fluidized bed reactor may be constructed with screen plates disclosed, for example, in U.S. Patent 3,230,246. In addition to the possible use of screen plates, most reactors use cooling tubes to indirectly contact the heat transfer fluid with the hot gases generated by the exothermic reaction. In all of these reactor structures, a substantially undivided reaction space is used, as required by the present invention.

As mentioned, the process of the invention uses two different catalysts instead of one. The first catalyst is selected from those catalysts known to be particularly effective in converting propylene or isobutylene to acrolein or methacrolein. The second catalyst is selected from those which are particularly effective in oxidizing acrolein or methacrolein to acrylic acid or methacrylic acid.

As mentioned above, the first catalyst is effective for preparing acrolein or methacrolein from the corresponding olefin. Roughly speaking, these catalysts are capable of selectively acting on the α-carbon atom of propylene or isobutylene without a double bond. From each olefin, the catalyst removes 2 hydrogen atoms from the alpha carbon atom and places oxygen in their place to form a carbonyl compound. Catalysts capable of performing this function are well known (see, e.g., the patents mentioned at the beginning). Each such catalyst can be used as the first catalyst in the oxidation catalyst of the present invention. These catalysts are oxides in an oxidation state determined by the environment. The term "oxide" refers to oxides, oxide mixtures, oxide complexes, solid solutions, and other similar structures.

Preferred catalysts that can be used as the first catalysts are those that contain at least molybdenum oxide. Of these catalysts, those containing at least oxides of bismuth and molybdenum are preferred, with the following formula being particularly preferred: AB, Fe D.Bi ΜοΊ o0 abcde 12 x wherein A is an alkali metal, alkaline earth metal, Zn, Cd, Ti, In, Nb, Ta, rare earth metal or a mixture thereof; B is nickel, cobalt, manganese or a mixture thereof; D is phosphorus, arsenic, antimony, boron, tungsten, chromium, vanadium or a mixture thereof; and a and c are numbers from 0 to about 10; e is a number greater than 0 but less than 10; b is a number from 0 to about 20; d is a number from 0 to about 5; and x is the number of oxygen required to meet the valence requirement of the other elements present.

Of these catalysts represented by the formula, catalysts in which b is a positive number are preferred because of the very advantageous results obtained when used. Preferred catalysts are also prepared using at least some tellurium instead of bismuth in the above formula.

u * n

The second catalyst contained in the oxidation catalyst is one which forms an acid from the aldehyde. Any catalyst capable of placing oxygen in the carbonyl portion of the aldehyde to form the corresponding acid can be selected as this catalyst. Representative, known examples of these catalysts are presented at the beginning of this brochure. These catalysts are also oxides that contain a number of oxygen determined by their environment.

Catalysts containing at least molybdenum oxide are preferred, with catalysts containing at least vanadium and molybdenum being of particular interest and catalysts of the following formula being highly preferred:

EeViM ° 120 * wherein E is Sn, CtJ, Ge, Sb, Bi, Te, Mn, Pe, Mg, Zn, Ni or a mixture thereof; G is W, Cr or a mixture thereof; and J is V, P, Sb, Co, or a mixture thereof, g and h are from 0 to about 20; i is a number greater than zero up to about 20; and x is the number of oxygen required to meet the valence requirement of the other elements present.

In the formula, those catalysts in which G is Wolfram and J is vanadium are preferred and those catalysts which contain tungsten, vanadium and tin, i. G is Tungsten, J is vanadium and E is tin are particularly preferred and those catalysts which contain tungsten, vanadium, tin and at least one of copper, nickel, iron, cobalt or manganese, i.e. G is Wolfram !, J is vanadium, E is a mixture of tin and at least one of copper, nickel, iron, cobalt or manganese, are of particular interest due to their highly advantageous catalytic effect in the reaction according to the invention.

Also of great interest as other catalysts of the formula are those catalysts which contain copper as one component. This is achieved by the formula if E is at least copper.

These two catalysts used as oxidation catalysts in the present invention are known in the art. Although a particular process for their preparation is important because of its catalytic effect, it is not an object of the invention and methods for the preparation of certain catalysts are set forth in the Examples.

As indicated above, the oxidation catalyst of the invention contains two different catalysts. In a preferred embodiment of the present invention, the oxidation catalyst comprises a physical mixture of the individual -A '· 6 61682 particles of the first catalyst and the separate particles of the second catalyst. Other methods for placing separate catalysts in a single fluidized bed reactor are readily available. For example, in the process of the invention, the catalyst charge may contain particles obtained from a mixture of two catalysts.

Another important property of the oxidation catalyst is the relative proportion of the two different catalysts. In a preferred embodiment of the invention, it has been found that substantially complete conversion of reactants to acids with aldehydes is formed in small amounts using an oxidation catalyst containing more than about 95% by weight of the first catalyst used to oxidize the olefin to the aldehyde. This catalyst mixture is used under the given conditions and a second catalyst (a catalyst which converts aldehydes to acids) is added until the desired low (less than 5 #) concentration of aldehydes is reached. Alternatively, a relatively large amount of aldehydes can be recovered from the reactor exhaust gases for use as aldehydes or for use as a feed to the fluidized bed reactor.

In the preferred use of the invention, about 5 to 10% by weight of the active ingredients of the oxidation catalyst is another catalyst, with about 10 to 30% by weight being even more preferred.

The oxidation catalyst used in the process of the invention may contain, in addition to the active catalysts, a solid, finely divided additive to improve the flow, to mitigate the effect of the heat of reaction, or for some other purpose.

As mentioned above, the process conditions, amounts of reactants and reaction parameters used in the present invention are previously known in the art. The reaction temperature is generally in the range of about 200 to 600 ° C, with temperatures of 300 to 500 ° C being preferred. As pressures, normal pressures, overpressures or underpressures can be suitably used.

Although the proportion of molecular oxygen can vary widely, the molar ratio of mole-oxygen to olefin is usually about 1-U. Calculated from air, this means that about 5 to 20 times the amount of air (vol.) Is used per unit volume of olefin. In addition to the reactants, suitably diluent gases such as steam, nitrogen and carbon dioxide may be added to the feed to improve temperature control and increase acid selectivity.

In other respects, the process of the invention is not critical. Certain procedures for carrying out the reaction are set forth in the Example. An important aspect of the invention is the finding that the use of two different catalysts in a fluidized bed reactor gives surprisingly high yields of acrylic acid and methacrylic acid.

Example - preparation of acrylic acid

The first catalyst useful in the preparation of acrolein from propylene and corresponding to the formula 90 »4 1 ° '* · Kn - <Ni0 Je.Bi.P.

υ · ΐ 40 j J- Μο1? Οχ and 9> 6 ft · a SiO 2 were prepared as follows: 1645 g Fe (NO 5) 5.9H 2 O, 986 g Ni (NO 3) 2.6H 2 O, 1777 g Co (NO 5) 2.6H 2 O and 658 g 3i (NO 2) 5 H 2 O was melted and 15-7 g dissolved in an equal amount of water was added. Separately, 6525 g of (NH 4) ε Mo 2 O 2 · 4 HgO was dissolved in water and 78 x 2 g of 85 ft 2 H 2 PO 4 and 397 g of silica were added. The resulting material was spray dried and calcined for 4 hours at 540 ° C. The catalyst was sieved to obtain the following particle size: 25 ft less than 44 micrometers, 70 ft between 44 and 88 micrometers, and $ 5 between 88 and 106 micrometers.

Another catalyst which is particularly useful in the preparation of acrylic acid from acrolein and has a formula corresponding to 62 ft W J Mo..0 and

JL f fc j ie X

38 ft SiO 2, was prepared as follows: Water was heated in a stainless steel vessel to 75 ° C. To the water were added 3923 g of (5H 2) 2 Mo 2 O 2 • 4H O, 606 g (? TH 2) g The mixture was spray dried and heated to 400 ° C for four hours and screened to obtain the same particle size as the first catalyst.

The fluidized bed reactor was made of a 3.8 cm inner diameter stainless steel tube with reactant inlet at the bottom and product outlet at the top. Inside the reactor and located along the entire length of the reactor were 12 sieve plates. The screen plates were constructed and mounted so that the catalyst particles could move throughout the reaction space.

A physical mixture containing 500 g of the first catalyst and 55.5 g of '\ / Γ' β 61682 second catalyst was charged to the reactor, giving a total catalyst charge length of about 0.5 ra. Under the air flow, the temperature of the catalyst charge was raised to 340 ° C.

The reactant flow in propylene air: water vapor at a molar ratio of 1: 10.1: 5 was passed over the catalyst at 4.2 cm / sec. at a linear rate and the ratio of propylene weight to catalyst weight per hour (WWE) was 0.031. The reaction was performed at 340 ° C and the exhaust gases were washed with water. The reactor was pre-operated for 30 minutes and the product was collected for 15 minutes. The product was analyzed by gas-liquid chromatography. The conversion obtained per feed in terms of moles of a given product multiplied by 100 and divided by the molar number of propylene fed was calculated. The conversion to acrylic acid per feed was 75.6 ° C and the conversion to acroline per feed was 9.8%. Thus, the conversion to acrylic acid and acrolein per feed was $ 85.4. Less than $ 0.05 of acetic acid was found in the product. The acrolein formed could be recycled or another catalyst could be used more to prevent the formation of acrolein.

As described above for the reaction of propylene, isobutylene can be reacted in the presence of a mixture of two catalysts to obtain a good yield of methacrylic acid.

Also, as above, other catalyst experiments are used to prepare unsaturated acids. Representative examples of the first catalyst include: Bi 2 Mo 2 O 2; Fe ^ ^ Bi ^ 5 ^ 0 5Mo12 ° xi USd ^ i FeSb ^ O ^ i WCU0.5Te2FeSt> 3 ° xi Bi0.2Cu0.8 ° xBP <V Sb2Bi6Mb12 ° x * Sn2Sb40x 'Te2CeMo120xi U ^ Mo ^ 2 ° x · Representative examples of the second catalyst include: ν6Κο12 ° χ! Cr5T8Mo12 ° 1ci P3Mo12 ° *! W6T1Mo12 ° x! Cu2Sn0O, 2W2V4Mo12 ° x! ^ Yio "00 *!

FeO, 2'fO, XSb2Mo3 ° x 'P0.5Sd2M ° 3 ° x' Kir, 2WV3I '! O12 ° xi Fe3I', lCr2V9ilO120x1 And Co ^ Sn ^ W ^^ gKo ^^ O ^. · The preferred preparation of some catalysts reduces molybdenum oxide with a fine metal such as tungsten.

In the same manner as described above, in which the catalysts were combined with a silica support, the catalysts may be supported by other materials such as aluminum, titanium, zirconium, alundum, calcium phosphate, or any other support suitable for use with the disclosed catalysts.

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