DD237058A3 - METHOD FOR PRODUCING CATALYSTS BASED ON ACTIVE CARBON - Google Patents

Abstract

Process for the preparation of catalysts based on activated carbon, which are preferably used in the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase at temperatures of 150 to 250C, with the aim to increase the activity and life of the catalysts. The technical object is achieved in that the active carbon used as a carrier has a transport pore volume of 0.45 cm3 / g to 1.0 cm3 / g, preferably from 0.50 cm3 / g to 0.60 cm3. The micropores of the activated carbon used take up more than 0.25 g of n-hexane / g of activated carbon and the n-hexane-loaded activated carbon reaches the exchange equilibrium n-hexane / n-heptane within a replacement time of 5 to 25 minutes in n-heptane, preferably within 7.5 to 15 minutes. The carrier activated carbon according to the invention is impregnated in a known manner with zinc chloride and / or with rare earth metal chlorides, preferably cerium and / or lanthanum, the zinc content being 5 to 20%, preferably 8 to 12%, and the content of rare earth metals 0 , 01 to 4%, preferably 0.01 to 0.7%. The catalyst according to the invention can preferably be used for the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase.

Description

Field of application of the invention

The invention relates to a process for the preparation of activated carbon catalysts, which are preferably used in the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase at temperatures of 150 ⁰ C to 250 ⁰ C.

Characteristic of the known solutions

It is known to use ZnCl ₂ activated carbon catalysts for the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase at 120 to 200 ⁰ C.

(DD-PS 83985)

It is also known that the initial activity and the lifetime of these catalysts depend on the activated carbon used as the carrier.

(DD-PS 85068)

DD 85068 describes a catalyst for the preparation of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase at temperatures of 120 to 200 ^° C., which contains 2% -20% zinc and 0.1% -2% as the active component. Ceritmetall contains. The carrier used is an activated carbon which has a ratio of basicity to acidity of at least 3: 1.

However, there are a number of activated carbons which have a basicity to acidity ratio of at least 3: 1 and are unsuitable as catalyst supports for the production of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase at 120 to 200 ° C.

Object of the invention

The object of the invention is to improve the activity and life of activated carbon catalysts, which are preferably used for the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol in the gas phase.

Explanation of the essence of the invention

- The technical problem of the invention

The invention has for its object to develop a process for the preparation of activated carbon catalysts, which have an increased life and activity and are preferably used for the synthesis of lower alkyl chlorides from hydrogen chloride and the corresponding alcohol 'n the gas phase.

Features of the invention

The technical problem is solved according to the invention in that the catalyst carrier used is an activated carbon having defined transport properties.

The activated carbon has a transport pore volume of 0.45 cm ³ / g to 1.0 cm ³ / g, preferably 0.50 cm ³ / g to 0.60 cm ³ / g. The micropores of activated carbon used absorb more than 0.25 g of n-hexane / g of activated carbon and the loaded with η-hexane activated carbon reaches in n-heptane the exchange equilibrium n-hexane / n-heptane within a replacement time of 5 to 25 minutes, preferably within 7.5 to 15 minutes.

The measurement of the exchange time is carried out so that the micropores of the corresponding activated carbon are filled with η-hexane and the thus treated activated carbon is added to a defined amount of n-heptane.

Measured are the amount of n-hexane absorbed by the activated carbon and the exchange time in which the equilibrium of the n-hexane / heptane exchange has been established.

The carrier activated carbons according to the invention, if they are preferably used as catalyst support for the synthesis of lower alkyl chlorides as hydrogen chloride and the corresponding alcohol in the gas phase, impregnated with ZnCl ₂ and rare earth metal chlorides, preferably cerium and / or lanthanum, as active component in a known manner in that the zinc content is 5% to 20%, preferably 8% to 12% and the content of rare earth metals is 0.01% to 4%, preferably 0.01% to 0.7%.

The catalyst according to the invention has an increased lifetime and an increased activity.

The invention will be explained in more detail by the following examples.

embodiments

The catalysts listed were tested in a known manner in the integral reactor at 180 ⁰ C. In each case 2 kg of catalyst were used. The measured quantities used were the conversion of hydrogen chloride and methanol to chloromethane after 8 hours (U ₆ ) and after 100 hours (U ₁₀₀ ).

Catalyst A: Carrier: activated carbon with the following properties Transport volume: 0.55 cm ³ / g

n-hexane uptake: 0.28 g / g

Exchange time: 10.2 minutes

Active component: 12% zinc

0.3% cerium

Activated carbon with the following properties: Transport pore volume: 0.21 cm ³ / g

0.23 g / g

28 minutes

12% zinc

0.3% cerium

Activated carbon with the following properties: transport pore volume: 0.38 cm ³ / g

0.26 g / g

31 minutes

12% zinc

0.3% cerium activated carbon with the following properties:

Catalyst B: Carrier:

Catalyst C: Carrier:

n-hexane uptake:

Exchange time:

Active component:

n-hexane uptake:

Exchange time:

Active component:

Catalyst D: support: (according to the invention)

Catalyst E: Carrier:

Transport pore volume: n-hexane uptake: exchange time: active component:

as catalyst A active component:

0.56cm ³ / g 0.34g / g 9.5 minutes 10% zinc 0.1% lanthanum

11% zinc

The catalysts were loaded with 1 volume of methanol / volume of contact and hour. The following sales were determined.

catalyst Uo (%) U ₁₀₀ (%) A 90 75 B 68 35 C 68 37 D 91 75 e 90 70

The examples listed make it clear that the catalysts used according to the invention have a higher activity and lifetime. Of decisive influence on activity and life is the activated carbon used, in particular their transport properties.

The addition of rare earth metals, preferably cerium and / or lanthanum, leads to an improvement in the long-term behavior of the catalysts.

Claims (2)

Invention claim: 1. A process for the preparation of catalysts based on activated carbon, which are preferably used in the synthesis of lower Aklylchloride from hydrogen chloride and the corresponding alcohol in the gas phase at temperatures of 150 ⁰ C to 25O ⁰ C, characterized in that the catalyst support an activated carbon with a Transport pore volume of 0.45 cm ³ / g to 1.0 cm ³ / g, preferably from 0.50 cm ³ / to 0.60 cm ³ / g is used, the micropores take more than 0.25 g of n-hexane / g of activated carbon, the activated charcoal loaded with η-hexane in n-heptane of the exchange equilibrium n-hexane / n-heptane within 5 to 25 minutes, preferably within 7.5 to 15 minutes. 2. A process for the preparation of catalysts based on activated carbon according to item 1, characterized in that the catalyst contains zinc chloride or zinc chloride and chlorides of rare earth metals, preferably cerium and / or lanthanum, wherein the zinc content of 5% to 20%, preferably 8% to 12%, and the content of rare earth metals is 0.01% to 4%, preferably 0.01% to 0.7%.