WO1991003318A1 - Copper silicate catalyst, process for making it and its use - Google Patents

Abstract

Solid copper silicate catalyst, especially for hydrolysing oils and fats and fatty acid methyl esters into fatty alcohols without a chromium content, in which there is a zinc content with an atomic ratio of zinc to the total quantity of zinc and copper of between 0.2 and 0.8 and especially between 0.3 and 0.6, with a specific area to BET of between 40 and 400 m?2/g, and especially between 150 and 350 m?2/g and with a molar silicon dioxide content of between 0.1 and 2 and especialy between 0.2 and 0.6.

Description

"Copper-silicate catalyst, its manufacturing process and its use"

The invention relates to a solid copper-silicate catalyst, in particular for the hydrogenation of oils and fats and of fatty acid methyl esters to fatty alcohols, without chromium content.

In contrast to a supported catalyst, this catalyst contains silicate within its active mass.

It is known to use copper catalysts in the catalytic pressure hydrogenation of natural fats, oils and fatty acid esters to fatty alcohols. A typical example is the copper chrome catalyst (Ullmaπns Encyklopadie der Technischen Chemie, Volume 11, Verlag Chemie, Weinheim, 1976, pages 431-434).

It is also known to use zinc-containing copper catalysts for the hydrogenation of fatty acid methyl esters if the double bonds of unsaturated fatty acid methyl esters are to be retained (DE book: fatty alcohols, raw materials, process and use, publisher: Henkel KGaA Düsseldorf, pages 58 and 59). However, these catalysts have a significantly lower activity than copper chromite catalysts. Other hydrogenation catalysts with the same or higher activity, which mainly contain nickel, cobalt, palladium or platinum as active components, do not achieve an economically acceptable selectivity for the hydrogenation reactions mentioned because of the formation of hydrocarbons.

Up to now, copper chromite catalysts have been best suited for hydrogenating oils, fats and fatty acid esters to the corresponding fatty alcohols because of their very high activity and selectivity. However, the disadvantage of these contacts is their chromium content, which leads to processing and disposal problems. The protective measures to be taken therefore increase the technical effort for the already very complex manufacturing process many times over.

However, it is not readily possible to eliminate or substitute chromium in the hydrogenation catalysts described in order to reduce the high production and disposal costs and to increase the operational reliability in the production of the contacts. It is known from the literature that in the copper chromite catalysts the copper component is the active phase for the catalytic activation of carbonyl functions and the chromium phase has hydrogen-activating properties. The combination of both functions results in the highly active catalyst. If the chromium phase in these hydrogenation catalysts is replaced by other elements or compounds, a decline in activity is to be expected since the synergistic system is disturbed.

A catalyst of the type mentioned is known from EP-PS 190617 B1. Such one is made by precipitating an aqueous copper nitrate solution in an acidic water glass solution Although catalyst is suitable in principle for the hydrogenation of fatty acid esters, like the copper-zinc catalyst mentioned above, it shows a considerably lower activity than a conventional copper-chromate catalyst.

The invention is therefore based on the object of developing a chromium-free catalyst of the type mentioned at the outset which, in its activity and selectivity, corresponds to or is even superior to the chromium-containing catalyst.

This object is achieved according to the invention by a content of zinc with an atomic ratio of zinc to the total amount of zinc and copper between 0.2 and 0.8, in particular between 0.3 and 0.6, with a specific surface dissolved according to BET between 40 and 400 πr / g, in particular between 150 and 350 πr / g and a molar silicon dioxide content between 0.1 and 2, in particular between 0.2 and 0.6.

Surprisingly, it was found that the activity of this copper-zinc catalyst produced by water glass precipitation is considerably higher than the activities of the zinc-free copper catalyst produced by water glass precipitation and also considerably higher than that of a commercially available copper-zinc catalyst. The activity of the catalyst according to the invention even exceeds that of the copper chromite contact known to date as the best catalyst for hydrogenation reactions.

Another advantage of this catalyst according to the invention is its tablettability. The geometrical shape of tablets, which is particularly advantageous in many cases for hydrogenation reactions, is therefore possible with this catalyst. - 4 -

On the other hand, the invention relates to a process for producing a catalyst of the type mentioned. According to the invention, copper and zinc are precipitated from their acidic salts by means of an aqueous water glass solution, the precipitated solid is calcined and then activated with hydrogen or a gas mixture containing hydrogen.

An activation temperature between 200 and 400 ° C., in particular between 250 and 350 ° C., is advantageous.

Another advantage of this production process, particularly with regard to its behavior towards non-deacidified oils and fats, is if calcination is carried out at a temperature between 300 and 700 ° C, in particular between 400 and 600 ° C.

For the use of the catalyst for the hydrogenation of oils, fats and fatty acid methyl esters, it is advantageous if the catalyst is pressed into tablets after the calcination.

The invention also relates to the use of a catalyst of the type mentioned in a process for producing fatty alcohols from deacidified or non-deacidified oils and fats or from fatty acid methyl esters by hydrogenation with hydrogen.

It is expressly pointed out that the catalyst according to the invention is not a supported catalyst, but rather a solid contact.

Exemplary embodiments and test results are illustrated below, which explain the invention in more detail. FIG. 1 shows a diagram in which the weight ratio of the C12- Fatty alcohol to the catalyst used is shown over the reaction time in minutes. The starting product in this case was ethyl laurate.

FIG. 2 shows a diagram with the dependence of the catalytic activity on the Cu / Zn ratio.

Example 1: Preparation of the catalyst on a laboratory scale

In a round-bottomed flask with 150 ml of distilled water, 17.8 g of a2Siθ2 «9H2θ are dissolved with stirring. In a second flask, 11.7 g Cu (N03) 2-2.5 H2O are dissolved in 75 ml distilled water. 3.28 g of Zn (θ3) 2 are added to this solution. H2θ given and solved at room temperature. The copper-zinc-nitrate solution is added dropwise to the strongly stirred sodium silicate solution over a period of 30 minutes. The stirrer speed is continuously increased during the precipitation. After the precipitation has ended, the suspension is stirred for five minutes, filtered and washed three times with 350 ml of distilled water. The filter cake is dried under normal pressure at a temperature of 120 ° C. The drying time is 16 hours. The filter cake is then ground into a fine powder.

The five-hour calcination is also carried out under normal pressure at a temperature of 500 ° C. The calcined material is pressed and crushed * with a load of 500 kp for 5 minutes. A fraction of 0.2-0.5 mm in diameter is sieved from the granules. The reduction of the particles takes place in a U-tube with dilute hydrogen (5% H2 in helium, flow rate 60 ml / min). The total reduction time is 15 hours. The temperature is raised to 280 ° C. in 10 hours and held for 5 hours.

For test purposes, the catalyst reduced in this way is added to 100 ml of methyl lauric acid and used in a 600 ml autoclave for the activity test. The weight of the catalyst is 2.5% by weight. The test takes place at 220 ° C under 70 bar hydrogen. The stirrer speed is 600 rpm. The quantitative analysis followed on a gas chromatograph using a flame ionization detector.

The activity of the different catalyst samples is expressed in conversion of grams of Ci2 alcohol per gram of reduced catalyst as a function of the reaction time. The higher activities of the new, zinc-doped copper silicate catalysts are shown in Figure 1 and Table 1 below. They are up to four times higher than conventional copper chromite catalysts.

Table 1

Catalyst activity (gr. C- [70H / min αr. Kata)

1) Cu-Si 0.0075

2) CuCr 0.0178

3) CuZnSi 0.0360

4) CuZnSi 0.0571

5) CuZnSi 0.0705

The numbering in the table corresponds to the numbering of the curves in FIG. 1. Example 2: Preparation of the catalyst on a pilot plant scale

In a 50 1 stirred autoclave, 1650 g Na2SiO3.5 H2O are dissolved in 18.6 1 distilled water with stirring at room temperature. 1500 g of Cu (03) 2.3H ₂ 0 and 460 g of Zn (Nθ3) 2-H θ are dissolved in 9.25 1 of distilled water in a second stirred container with 30 1 content. The sodium silicate solution is stirred vigorously and additionally circulated with an external pump. The Cu-Zn nitrate solution is pumped to this solution from the second container within 30 minutes. The suspension is 30 min. stirred. Then it is filtered and washed three times with 40 liters of distilled water.

The filter cake is dried in a drying cabinet at 120 ° C. for 10 hours and then ground into a free-flowing powder. The calcination is carried out over 5 hours at a temperature of 500 ° C., analogously to Example 1. The same applies to the catalyst activation with a hydrogen-helium mixture.

The activity coefficient determined from the standard activity test is 3.46.10 ~ 2g Ci2-0H / min.g Kata. This activity is also higher than that of conventional copper chromite catalysts. Table 2 shows the physical data (density, BET surface area) and the oleochemical parameters (VZ _f OHZ) for the copper silicate catalysts from the pilot plant approaches. Here too, the ne :: n copper silicate catalyst is clearly superior in hydrogenation activity compared to the conventional copper chromite catalyst. TADELLE

Physical data and activity results of copper silicate catalysts from the pilot plant approach

Testbedinqunqent

Pressure 70 bar hydrogen

Temperature 220 ° C

Okutoclave vol. 1.5 1

Substrate 600 g of methyl laurate

Kata use 2.5%

Duration 5 hours

Example 3 (data not listed as in Example 3) Continuous hydrogenation in a fixed bed reactor

Claims

Claims 1. Solid copper-silicate catalyst, in particular for the hydrogenation of oils and fats and of fatty acid methyl esters to fatty alcohols, without chromium content, g e k e n n e e i c h n e t d u r c h. a content of zinc with an atomic ratio of zinc to the total amount of zinc and copper between 0.2 and 0.8, in particular between 0.3 and 0.6, with a BET specific surface area between 40 and 400 m g, in particular between 150 and 350 m - ^ / g and with a molar silicon dioxide content between 0.1 and 2, in particular between 0.2 and 0.6. 2. Catalyst according to claim 1, g e k e n n z e i c h n e t d u r c h the geometric shape of tablets. 3. A process for producing a catalyst according to claim 1 or 2, characterized in that copper and zinc are precipitated from their acidic salts by means of an aqueous water glass solution, the precipitated solid calcines and then activated with hydrogen or a gas mixture containing hydrogen becomes. 4. The method according to claim 3, characterized by an activation temperature between 200 and 400 ° C, in particular between 250 and 350 ° C. 5. The method of claim 3 or 4, d a d u r c h g e k e n n z e i c h n e t that at a temperature between 300 and 700 ° C, in particular between 400 and 600 ° C is calcined. 6. The method according to any one of claims 3 to 5, that the catalyst is pressed into tablets after the calcination. 7. Use of a catalyst according to one of claims 1 to 6 in a process for producing fatty alcohols from deacidified or non-acidified oils and fats or from fatty acid methyl ester by hydrogenation with hydrogen.