CS212754B2 - Catalyst in the production of unsaturated acids - Google Patents

Abstract

1482686 Oxidation catalyst STANDARD OIL CO 17 Dec 1974 [26 Dec 1973] 54373/74 Heading B1E [Also in Division C2] An oxidation catalyst composition for the conversion of acrolein or methacrolein to the corresponding acids consists of oxides or oxide complexes of tungsten, vanadium, molybdenum and uranium or thorium or a mixture thereof. It may further contain one or more of Fe, Co, Ni, Zn, Cn, Mg, Mn, Bi, Ti, Zr, Sn, P, alkali metal, alkaline earth metal, lanthanium or the lanthamides and may have the empirical formula where A is Fe, Co, Ni, Zn, Cu, Mg, Mn, Bi, Ti, Zr, Sn, P, an alkali metal, an alkaline earth metal, lanthanum or a lanthanide or mixture thereof; D is U and/or Th; a is 0 to 5; b, c and d are 0.1 to 10; e is 6 to 16; and x is a number to satisfy valency requirements. The composition may comprise a support, e.g. silica, alumina, zirconia, titania, silicon carbide or boron phosphate. The catalyst may be prepared by combining precursors in an aqueous slurry, evaporating to dryness and calcining. Suitably, the preparation is such as to provide molybdenum in a state partially reduced below the hexavalent. The Examples describe the formation and use of U 2 W 1À2 V 3 Mo 12 O x .

Description

Catalyst for the production of unsaturated acids, consisting of oxides or complexes thereof, containing tungsten, vanadium and molybdenum, the catalytically active component of which:

empirical formula

Sn _and DbWcVdMoeOx where it means

D uranium, thorium or a mixture thereof, and 0 to 5, b, c, -d 0.1 to 10, e 6 to 16, x the number of oxygen atoms required to satisfy the valency requirements of the other elements present.

The catalyst according to the above formula is highly active, has selectivity and is usable even at low temperatures.

The invention relates to a catalyst particularly suitable for the production of unsaturated acids. U.S. Pat. No. 3,567,773 discloses compositions containing tungsten, vanadium and molybdenum similar to the catalysts of the present invention which contain uranium or thorium and are very suitable catalysts for the production of acrylic and methacrylic acid.

The preparation of -acrylic acid by oxidation of acrolein and the production of methacrylic acid by oxidation of methacrolein are known per se. The invention therefore relates to a novel catalyst for these known processes.

The catalyst composition according to the invention comprises oxides or oxide complexes with a catalytically effective amount of uranium, thorium or a mixture thereof, tungsten, vanadium and molybdenum and optionally tin. These catalysts are particularly effective for preparing acrylic acid from acrolein and methacrylic acid from methacrolein. The catalysts are also highly effective in oxidation reactions such as the oxidation of butadiene to maleic anhydride, and the oxidative esterification of unsaturated aldehydes to the corresponding unsaturated esters. The catalysts of the invention are highly reactive and capable of considerable selectivity in oxidation. -acrolein to acid, and-. at low temperatures, with little or no acetic acid at all.

Accordingly, the present invention provides a catalyst for the production of unsaturated acids consisting of oxides or complexes thereof containing tungsten, vanadium and molybdenum, characterized in that the catalytically active component has an empirical formula

..... .. Sn _and DbWcVdMo _e O _x where

D uranium, thorium or a mixture thereof, and a to 0, 5, b, c, d 0.1 to 10, e 6 to - 16, x number - oxygen atoms necessary to satisfy the valency requirements of the other elements present.

Catalysts similar to the catalysts of the invention are known, see, for example, U.S. Pat. No. 3,567,773, and can be readily prepared by one skilled in the art. ,;

Usually, the catalysts of the invention are prepared by mixing the catalyst components in suitable proportions in an aqueous mixture followed by drying of the aqueous suspension obtained. by subsequent calcination of the product. The individual components can be used in the form of oxides, halides, nitrates and other similar salts in the preparation of the catalyst. The optional carrier is usually mixed with the other components to prepare the catalyst. After mixing the catalyst components to form an aqueous suspension, the suspension is evaporated to dryness and the dried solid is heated to 200 to 600 ° C in the presence of air. Said tinning can be carried out outside the catalytic reactor or by in situ activation.

Preferred catalysts according to the invention contain molybdenum in a partially reduced state, i.e. of a valency lower than hexavalent. Catalysts of the invention containing molybdenum in reduced form are described in specific examples.

Of the catalysts of formula (I), those wherein more than -50% by weight, with the exception of oxygen and an inert carrier, are molybdenum and which optionally contain tin, are preferred.

In addition to the active catalyst components, the catalysts of the present invention may contain a support material, and suitable support materials include silica, alumina, zirconia, titanium dioxide, silicon carbide, borophosphate and the like. The preferred support material is silica.

As mentioned hereinabove, the catalysts of the present invention are suitable components in various oxidation reactions. Among these reactions, the process for producing unsaturated acids from the corresponding unsaturated aldehydes is preferred. Such a process produces acrylic acid or methacrylic acid by reacting acrolein or methacrolein with molecular oxygen in the presence of a temperature of about 200 ° C to about 500 ° C. Of particular importance is the production of acrylic acid - from acrolein, in view of which it is particularly desirable to make such an auction; results.-.- .- ..... 03: Čxj-daoe. - unsaturated / aided-on: - pendulum km of the corresponding acid; well known; Essentially, it relates to the present invention; with regard to the process of using the new catalysts within the parameters - known processes.

The known process relates to a process in which the unsaturated aldehyde is contacted. in the presence of - - - vapor -, -a; at about 200 ° C to about 500 ° C. The ratio of reactants can vary considerably with the molar ratio of molecular oxygen to aldehyde, and is usually used. -0.5 to - about 5 moles. -Molecular oxygen is usually added in the form of air. The amount of steam may vary considerably from the very small amounts produced by the reaction, up to 20 moles or more, of moles of steam per mole of aldehyde. In a preferred embodiment of the process of the invention about 1 to 10 moles of steam are added to the feed of the reactants.

The reaction can be carried out in a moving bed or fixed bed reactor at normal, higher or lower pressure. The apparent contact time may vary substantially from fractions of a second up to 20 seconds or more.

Using the catalysts of this disclosure. very suitable yields of unsaturated acids at low temperatures can be obtained, while producing a small amount of acetic acid,. optionally without acid at all. -acetic.

Comparative example - A and -. Examples 1 to 3

The catalyst according to the invention compared to the - usually used

The base catalyst of the present invention is prepared and compared to the catalyst of U.S. Pat. No. 3,567,773. The catalysts are prepared as follows:

Comparative example

Catalyst 62%. . Wi, ₂ µMi ₂ O _x and 38% SiO 2. -s ready. according to Example 6 of U.S. Patent 3,567,773.

Examples - - 1 to 3 ............

U ₂ W _lj2 V3Mo ₁₂ O _x

The aqueous suspension is prepared in 500 ml of distilled water. The suspension contains 72.0 g of molybdenum trioxide, 11.36 g of vanadium oxide and 9.19 g of powdered tungsten metal. The suspension was heated to reflux for 2 hours; during this time the color of the suspension changes to blue-black. .

Separately, -35.3 g of -UoáCCHHOjjz is dissolved. 2H 2 O - in water and the resulting solution is added to the suspension. The resulting mixture was heated under reflux for an hour and then concentrated to a consistency of the paste which was dried in an oven overnight at 110 ° C. The catalyst is ground and sieved to give a particle size fraction of 2 to 0.595 mm.

The above catalysts are placed in a 1 cm stainless steel reactor with a reaction zone of 20 cm ³ . The catalyst according to the invention is activated by heating for 2 hours in an air stream at a temperature of - 400 ° C. The acrolein / air / steam mixture is fed to the reactor in a 1/10/6 molar ratio. ..The heater block temperature and apparent contact time are always given in Table 1.

The results are also shown in Table 1 and ibid - the terms are defined as follows:

Yield in one pass = moles of product isolated, 100 moles of acrolein in the feed of the acrolein-reacted. 100 aols of acrolein in feed

Selectivity = (moles of recovered acrylic acid. 100 moles of reacted acrolein

Table 1

Comparison of CeWVMo catalyst with WVMo in acrylic acid preparation

Example Catalyst Temperature Contact Yield for a Single Conversion Selective ........% Acid Acetic Acid Time

1 ^ Wi ^ VaMOuOx 271 2,0 82.5 0.3 100 ALIGN! 82.5 2 UWAM Oi2Ox 246 2.2 92.7 0 100 ALIGN! 92.7 3 U ₂ Wi, 2V3Mo ₁₂ O _x 232 2.3 65.5 0 70.6 92.7 Srovná- Wi, ₂ V3Mo ₂ Ox 274 1,8 80.4 6.3 99.6 80.7

vací

Example 4

Example 5

Catalyst composition

Catalyst of composition

Mo ₁₂ V3W _1, Th _{2 2} 0 _x

Mo ₁₂ V W W Sn Sn U os OOK is used to oxidize acrolein to acrylic acid. The reaction is carried out at a mole ratio of acrolein, air and steam of 1/10/6 at an apparent-contact time of 2.2 s and at a temperature of 232 ° C. There was 96.6% overall conversion, with 87.1% conversion to acrylic acid and 91.1% selectivity to acrylic acid.

is applied in an amount of 20% to the alumina beads.

Acrolein is oxidized to acrylic acid in a 20 ml solid-bed reactor using acrolein, air, nitrogen, steam ratio of 1 / 8.5 / 2.5 / 6, at a contact time of 1.94 s and at reactor temperature. 288 ° Celsius. The single pass conversion to acrylic acid is 91.1%, the total conversion is 98.8% and the selectivity with respect to acrylic acid is 92.3%.

In the same manner as described in the above examples, other catalysts of the present invention may be used, containing thorium instead of uranium, or containing other amounts of uranium or thorium and optionally other elements such as iron, cobalt, nickel, zinc , copper, magnesium, manganese, bismuth, titanium, zirconium, tin, phosphorus, alkali metal, metal. alkaline earths, lanthanum, an element of the lantanold group or mixtures thereof, in the manufacture of acrylic acid. In addition, activated catalysts containing varying amounts of tungsten, vanadium and molybdenum can be used.

Using the catalysts of the present invention, maleic anhydride, methacrylic acid or acrylic esters may also be prepared using known oxidation procedures.

Claims (2)

Catalyst - for the production of unsaturated acids, consisting of oxides or oxides. their complexes containing tungsten, vanadium. and molybdenum, characterized in that the catalytically active component has an empirical formula. Sn _a D _b WcVdMo _e O _x where D uranium, thorium or a mixture thereof, and 0 to 5, b, c, d 0.1 to 10, e 6 to 16, x the number of oxygen atoms. necessary to satisfy the valence - requirements of others. present elements. 2. Catalyst according to claim 1, characterized in that more than 50% of the atoms, apart from oxygen and the inert support, are molybdenum.