DE2719299A1 - METHOD FOR MANUFACTURING VANADINE MOLYBDAEN CATALYSTS - Google Patents

Description

PATENT LAWYERS CELLENT

ZWEIBRUCKEnSTR. 15th
8OOO MUNICH 22

Instytut Chemii Przemyslowej April 29, 1977

Warszawa / Poland As / Os

CW 14A

Process for the production of vanadium-molybdenum catalysts

The invention relates to a method for producing Vanadium-molybdenum catalysts used in the production of maleic anhydride by the oxidation of benzene in the gas state be used. Catalysts, vanadium pentoxide and molybdenum trioxide, are commonly used in this process contain, whose variable molar ratio MoO, to V ^ Oc usually within the limits of MoO, / VpOc - 0.3 - 1.2. In addition to the above-mentioned oxides, active vanadium molybdenum mass normally also contains oxides of such elements as promoters like Li, Na, K, Co, Ni, Fe, Cr, Cu, Ag, W, U, P, Te, Ta and others.

on the catalytic properties of vanadium-molybdenum catalysts decide: their chemical and phase composition, the applied carrier and its structure, type and

7098A6 / 0978

Concentration of promoters and also that for its production Process used which has a significant influence on the quality of the catalysts.

These catalysts are most often produced by applying the active composition accordingly to a carrier having a low specific surface area. As a rule, electrical corundum, carborundum and sintered corundum made of oC-Al ₂ O come into question.

In the case of the carrier contacts, the active compound is applied to a carrier, i. H. the carrier comes with a specially designed to impregnated solution prepared for this purpose. This impregnation solution contains a corresponding aqueous solution of mineral - or salts dissolved in organic acids. Sometimes the application of the active material to the carrier is done after Sintering method using an appropriate salt or Oxide mixture carried out. The catalysts obtained by impregnating the support with aqueous solutions are after completion of the impregnation process dried and then calcined, usually at a temperature of 320 to

All types of stationary catalysts used in the process of partial oxidation of gaseous benzene must have considerable mechanical strength as well as thermal stability, since under industrial working conditions they are uninterrupted for periods of 2-3 years

709846/0978

^ς 2719293

in about 3 m thick catalyst beds at temperatures up to about 400 ^° C., which can be even higher in the reaction zone.

For the production of maleic anhydride, vanadium-molybdenum- Catalysts used that are made by impregnating the support with a dissolving vanadium pentoxide and Molybdenum trioxide in concentrated hydrochloric acid in the hot state prepared solution. In this way Catalysts with high activity and high stability are obtained and it is also uniform Distribution of the active material on the carrier granules and their good adhesion achieved.

During the dissolution of the vanadium p ^ entoxide in concentrated Hydrochloric acid releases atomic chlorine, which, as is well known, is chemically very active, which is why it is used chemical apparatus very high requirements in terms of their chemical resistance must be made, which accordingly high construction costs. In addition, concentrated hydrochloric acid and the chlorine released in the process for the Operating personnel working in the manufacture of the catalytic converter always represent and cause a potential hazard also poisoning the environment. For the reasons mentioned, i. H. for reasons of occupational safety and hygiene and also to reduce the production cost of the catalyst it would be desirable to use hydrochloric acid

709846/0978

to be avoided in the manufacture of the catalyst. That Process for the preparation of catalysts by impregnating a support with solutions obtained by dissolving the corresponding Vanadium and molybdenum salts and corresponding promoters are prepared, provides catalysts that are used in the Oxidation of benzene to maleic anhydride gives too low yields and therefore those from the current standpoint Technology of these catalysts do not meet the requirements. That is why catalysts produced in this way are found no industrial application.

Better, more active catalysts can be produced if the solvent is not water, but highly concentrated ones aqueous solutions of certain organic acids, including oxalic acid, are used. When using the latter 3-6 moles of oxalic acid are used based on 1 mole of the imported vanadium pentoxide. It is true that the choice makes it more such Concentrations of oxalic acid or another organic acid in the solution have good solubility of the introduced Salts achieved, but at the same time this results in a sticking of carrier granules or even in the last impregnation stage causes caking of the entire catalyst mass produced. In addition, this manufacturing method uses a low adhesion between the active material and the carrier achieved, which is not only the production of the catalyst additionally difficult, but also disadvantageous Polgen in its industrial use in the stationary catalyst bed Has.

709846/0978

The invention is based on the object of a simple ^ and Cheapest possible method for the production of vanadium molybdenum ^ atalysatoren to specify. Catalysts produced by such a process are said to be subject to oxidation of benzene in the gas state give high yields of maleic anhydride. They should also work under industrial conditions have a long service life.

It has surprisingly been found that the method for Manufacture of vanadium-molybdenum catalysts can be significantly simplified if the previous dissolving of the constituents the active catalytic mass in concentrated mineral acids or in large quantities of organic acids simply dissolving the constituents in water is replaced. According to the invention, this is achieved in order to achieve the object set aqueous solution a small, precisely determined amount of an organic acid or its ammonium salt with reducing Properties added, being the amount of acid or their

I'iol
Ammonium salt is 0.4-1.2 / per 1 mol of dissolved vanadium pentoxide. An inert, porous carrier substance having a low specific surface area is impregnated with a solution prepared in this way.

The impregnation solution for the vehicle is as follows prepared: The ammonium salt of vanadium or the vanadium pentoxide is dissolved in hot water, then in of this solution molybdic acid, its anhydride or its ammonium salt

709846/0978

dissolved, the ratio of MoO * / VoO ₁ - being within the limits of 0.3 to 1.2. However, it is particularly advantageous to use a catalyst in which the quantitative ratio of the oxides mentioned is within the limits of 0.3-0.6. In addition, known promoters such as phosphorus and sodium, as well as one or more metallic elements such as Ni, Co, Fe, Cu, Ag, K, Cd, Cr, W, U, Te, Ta or possibly others are added to the solution. These promoters are added orin well soluble salts in ^, in aenen the second component under the conditions of the temperature range of 200 - 400 ⁰ C extending Katalysatorkalzinierung is volatile. As a result, the salts of the metals mentioned change into oxides. A reducing agent in the form of an organic substance soluble in water, such as, for example, a corresponding organic acid or its ammonium salt, is also introduced into the finished solution. The reducing agents used are ammonium oxalate, oxalic acid, citric acid, ascorbic acid, maleic acid, formic acid or their ammonium salts, which are added to the solution in amounts of 0.4 1.2 mol, preferably 0.6-1.0 mol to 1 mol of the solution Vanadium pentoxide in the form of a corresponding soluble salt can be added. The solution prepared in this way becomes an inert, porous support with a low specific surface area of the order of magnitude

2
0.01 - 1.0 m / g impregnated. The vessel is heated in the rotating "carrier substance with the impregnation solution at a temperature of 60-200 ⁰ C is poured over. After all of the impregnating solution has been used up, the catalyst obtained becomes

709846/0978

dried and ziniert in the temperature range of 200 - & J0 ο xaT.

The inventive method for producing vanadium-molybdenum catalysts shows a number of distributions compared to the methods used so far;

The use of concentrated hydrochloric acid and other "solvents, the use of which is cumbersome, harmful and expensive is avoided. Instead, the components of the Dissolved catalytic mass according to the invention in hot water and then small, precisely determined amounts of organic substances with reducing properties are added to the solution such as oxalic acid or its ammonium salt, citric acid, maleic acid, ascorbic acid or its ammonium salts are added.

This also makes the use of an expensive acid-resistant apparatus superfluous, which makes the method according to the invention is much cheaper and this compared to the known manufacturing process for vanadium-molybdenum catalysts Type is much more convenient. According to the method according to the invention Catalysts produced are characterized by good mechanical strength and good adhesion of the active composition to the support as well as characterized by long service life under working conditions. The use of these catalysts guarantees that a high conversion of benzene in maleic anhydride is achieved.

The process of making vanadium molybdenum oxides containing Catalysts used in the manufacture of male

709846/0978

acid anhydride can be used by oxidation of benzene in the G, is shown below with reference to examples explained in more detail.

Example 1: 250 g of vanadium ammonium salt, 104 g of molybdic acid monohydrate and 12 g of nickel nitrate are added to 6 liters of water. 6 ^ 0, 13.3 g sodium chloride, 3.9 g phosphorus pentoxia and 91 g oxalic acid dissolved. Tantalum pentachloride dissolved in 20 ml of absolute ethyl alcohol is then added to this solution. With the thus prepared solution, a is located in a rotating quartz vessel, consisting of sintered alumina carrier substance is poured over slowly, said vessel is heated with the flame of a gas burner so as "means the temperature of the medium within the limits from 80 to 100 ⁰ C. . Xach is held to the consumption of the total amount of the prepared impregnating solution, that is, after completion of carrier impregnation, the temperature of the rotating quartz vessel is slowly at 300 - increases 3SO ⁰ C, wherein the catalyst obtained in 2 - is calcined for 3 hours and then the heating is. switched off and about 15 minutes later the rotation of the rotating vessel also stopped.After it has cooled down, the catalyst is sieved to remove contact dust and any lumps that may have arisen from agglomeration of granules.

The catalyst obtained is put into a unitary reactor with a 3 m long pipe, which is heated with a molten bath, poured. A mixture is produced through this reactor of gaseous benzene and air with a concentration of 42 g of benzene per m of air, the load being 120 g Benzene to 1 liter of catalyst in one hour.

709846/0978

ORIGINAL INSPECTED

The process is carried out at 300.degree. With a total benzene conversion of 97%, the yield of sharkic anhydride is 75 %.

Example 2: As in Example 1, the ingredients of the active composition are dissolved in 6 liters of water, each is the Oxalic acid has been replaced by 103 g of ammonium oxalate. Kit of the solution prepared in this way, which otherwise contains the other components in the amounts specified in Example 1, the carrier is impregnated. Then the obtained Catalyst dried and calcined as in Example 1. When using this catalyst, a total benzene conversion of 97 mol%, a maleic anhydride yield of ^ scored.

Example 3- The individual components of the impregnation solution are dissolved in 6 liters of water as indicated in Example 1, but the oxalic acid has been replaced by 71 g of maleic anhydride. With the thus prepared impregnation the impregnated carrier is exactly as in Example 1 and the resulting catalyst is _t as indicated there, dried and calcined. When this catalyst is used, benzene is oxidized to maleic anhydride in the gas state with a total benzene conversion of 91 Mcl% with a yield of 86 mol%.

Example 4: In 6 liters of water, the components of the active material dissolved as in Example 1, but the nickel nitrate has been replaced by 22 g of silver nitrate. With this solution, which otherwise contains the remaining ingredients in the amounts given in Example 1, became the carrier

709846/0978

2719293

Example 7 The individual constituents of the impregnation solution are dissolved in 6 liters of water as in Example 1. An additional 4 g of KiJ O are added to this solution. However, the solution does not contain tantalum pentoxide. The carrier is impregnated with the kit of the solution prepared in this way, which contains identical amounts of the remaining components as in Example 1. The catalyst obtained is dried and calcined in the same way as in Example 1. When using this catalyst, maleic anhydride is obtained with a yield of 73 Mcl% in the process carried out at 400 ^{° C. with a total benzene conversion of 96 mol%.}

Example 8: As in Example 1, the individual components of the impregnation solution are dissolved in 6 liters of water, but without the addition of the tantalum oxide. The nickel nitrate is replaced by 17 g Cu (KO,) ₂ .

With this solution, which identical amounts of the remaining ingredients as in Example 1, the carrier is impregnated. The catalyst obtained is exactly as in Example 1 dried and calcined.

With this catalyst, a maleic anhydride yield of 68 mol% is achieved in the process carried out at 430 ^° C. with a total benzene conversion of 93 mol%.

709846/0978 ORIGINAL INSPECTED

impregnated. The catalyst obtained is dried and calcined as in Example 1. With the catalyst prepared in this way, ^{a maleic anhydride yield of 75 mol% was achieved in the process carried out at 500 °} C. with a total benzene conversion of 97 mol / 6.

Example 5: The individual constituents of the impregnation solution are dissolved in 6 liters of water as in Example 1, but the rickelnit ^ at has been replaced by 22 g of AgNO, and no valley pentoxide was added. The carrier is impregnated with the solution prepared in this way, which otherwise contains the same amounts of other components as in Example 1. The catalyst obtained is dried and calcined in the same way as in Example 1. With the catalyst prepared in this way, a maleic anhydride yield of 66 N o 15 »has been achieved in the process carried out at ^ 20 G with a total benzene conversion of 94 mol ^.

Example 6: The individual components of the impregnation solution are dissolved in 6 liters of water in the same way as in Example 1, however, the nickel nitrate is by 22 g AgITO, and the oxalic acid has been replaced by 103 g of ammonium oxalate. With the solution prepared in this way, the identical amounts of Contains other components as in Example 1, the carrier is impregnated. The catalyst obtained is as in Example 1 dried and calcined.

Using the catalyst thus prepared, maleic anhydride is obtained in a yield of 73 mol% at a total benzene conversion of 97 mol% gained.

7098 46/0978

Claims (3)

PATENT LAWYERS ₀₀ . .. CELLENT ²⁹ ' ^Aprl1 ZWEIBRUCKENSTR, 15 /-.y ÖOOO MUNICH 22 AS / S Claims ⁽ Aj process for the production of a vanadium-molybdenum catalyst suitable for the catalytic oxidation of benzene to maleic anhydride in the gas state by impregnating an inert porous support with an aqueous solution, the components of the catalytic mass such as vanadium and molybdenum salts in a ratio of colybdenum trioxides to vanadium pentoxide of 0.3-1 »2 and promoters, and subsequent evaporation of the volatile substances and calcining, characterized in that the components of the catalytic mass are dissolved in the water and organic substances with reducing properties such as acids and / or their ammonium salts in this solution Quantities of 0.4-1.2 moles of acid or salt per 1 mole of vanadium pentoxide are added. 2. The method according to claim 1, characterized in that the reducing substances oxalic acid, citric acid, Ascorbic acid, formic acid, maleic acid or their ammonium salts can be used. 709846/0978 ORIGINAL INSPECTED 3. The method according to claim 1, characterized in that in the impregnation solution as promoters phosphorus and sodium and one or some of the following elements Ni, Fe, Co, Ag, Cu, Cr, Cd, U, W, K, Te, Ta to be introduced. 709Ö46 / 0978