CS230464B1 - Dehydrogenation ferric catalyst with high selectivity - Google Patents

Abstract

The invention solves the problem of improving the selectivity and activity of the catalyst according to Czechoslovak Patent Application No. 168 220. A dehydrogenation iron catalyst with high selectivity according to Czechoslovak Patent Application No. 168 220, suitable for the dehydrogenation of alkylaromatic and alkylheterocyclic substances to alkenylaromatic and alkenylheterocyclic substances and olefins to diolefins, consists of 25 to 96.4 wt. % iron oxide, 2 to 30 wt. % potassium oxide* 0.1 to 5 wt. % molybdenum or tungsten oxide, 1 to 10 wt. % titanium dioxide, and optionally contains chromium compounds. The improvement of selectivity and activity is achieved by adding 0.5 to 65 wt. % cerium compounds, calculated as cerium dioxide.

Description

The invention relates to a dehydrogenation iron(III) catalyst with high selectivity according to Czech Patent Application No. 168 220, suitable for the dehydrogenation of alkylaromatic and alkylheterocyclic substances to alkenylaromatic and alkenylheterocyclic substances and olefins to diolefins.

The basic component of ferric dehydrogenation catalysts is ferric oxide, which changes during dehydrogenation to ferrous iron oxide. The presence of alkalis in the catalyst is also indispensable, as they are a promoter of the catalyst's autoregeneration, of which potassium salts are the most commonly used. Selectivity promoters are added to these basic substances, which can be, for example, boron compounds, as stated in Czech Patent No. 104,763, or even more effective is the addition of vanadium compounds in combination with molybdenum or tungsten compounds and titanium dioxide, as stated in Czech Patent No. AO 168,220. It is also known to commonly add structural promoters to this type of catalyst, of which the most commonly used are chromium compounds, which usually do not affect the catalyst's selectivity, but extend its service life.

It has now been found that a catalyst with even greater selectivity and activity than that corresponding to the catalyst according to Czech Patent No. AO 168 220 is obtained if the catalyst according to Czech Patent No. AO 168 220 additionally contains cerium compounds instead of part of the iron oxide. The overall improvement in selectivity with the new catalyst is on average 1 to 3 mol% and is particularly significant at higher conversions, the improvement in activity is on average 5 to 10 °C.

230,464

According to the invention, the iron (β) dehydrogenation catalyst with high selectivity according to Czech Patent Application No. 168 220, optionally containing cerium compounds, contains 0.5 to 55% by weight of cerium compounds, calculated as cerium dioxide. Example 1

A catalyst according to the invention was prepared with the following composition:

in a delicate mass composition: PegOj 80% In ₅ 3 % To ₂ 0 10% Mo0 ₃ 1 % TlOg 5% OeOg 1 %

The diameter of the extrudates was 3 to 4 mm, length 5 to 7 mm. This catalyst was tested in a reactor for the dehydrogenation of ethylbenzene to <pc styrene. The catalyst was tested in an isothermal stainless steel reactor with a diameter of 25/22 mm and a length of 1200 mm. 50 ml of catalyst was placed in a boron bag, onto which 25 ml/h of ethylbenzene and 65 ml/h of distilled water were injected. After passing through the reaction zone, the gases were cooled in a cooler and the condensed hydrocarbons were separated from the water. The conversion to styrene and selectivity were calculated from the chromatography analysis of these hydrocarbons and the outgoing uncondensed gas and from their amounts.

Testing was carried out continuously for 110 h, with the first 50 h not taken into account. The reaction temperature was chosen so that the conversion to styrene was constant at 40% or 50% by weight. The testing results are shown in Table 1.

Example 2

A catalyst according to the invention was prepared, containing compounds of the invention, with the following final mass composition:

230,404

² °3 69% ^To 2° 10% Ce0 ₂ 10% Ti0 _o 5%

Testing results

Cr ₂ O ₃ 2% V ₂ O ₅ 2% WO ₃ 2% are listed in Table 1.

Example 3

A catalyst according to the invention was prepared with the following final mass composition:

in

50% ₂ people 5% 31% at ₂ o'clock ₅ 3% 10% KoO- 1%

are listed in Table 1.

Testing results

Example 4

A catalyst was prepared according to Ss· AO No· 168 220, example No* 4 of the description for comparison with this final mass composition:

Pe ₂ O ₃ 61% v ₂ o ₅ > %

KgO 10% m©o ₃ 1%

_Ti0g 5%

The test results are shown in Table 1.

Table 1

Catalyst

Conversion to styrene in % mass Temperature in °0

Selectivity in % mol*

Ex.No.! Ex.No.2 Ex.No.3 according to the invention

40 40

555 552 547

95.3 96.0 97.1

Ex. No. 4 according to AO 168220

555

94.7

230,404 Conversion to styrene in wt% 50 50 50 50 Temperature in °C 573 570 565 575 Selectivity in % mol 94.4 95.0 96.1 93»

Example 5

3$yl prepared catalyst as in example 1·

The testing was carried out by spraying isopropylbenzene, the rest of the procedure being the same as in the previous examples. The results in comparison with the reference catalyst according to EP 0 168 220, given in Example 4 of this invention, are given in Table 2.

Table 2

Catalyst

Example 5 Example 4

Conversion to alpha-methylstyrene in % by weight *

Temperature in °C 546

Selectivity in % mol 96.8

546

96.1 — 6

230,484

Claims (1)

SUBJECT OF THE INVENTION Dehydrogenation ferric catalyst and high selectivity according to AO 168 220, optionally containing tremendous compounds, characterized in that it contains 0.5 to 55% by weight of cerium compounds per cerium oxide ·