A method for improving the selectivity of a catalyst and a process for the epoxidation of an olefin

A high-selectivity, catalyst technology, applied in the direction of catalyst activation/preparation, chemical instruments and methods, physical/chemical process catalysts, etc., can solve problems such as low selectivity

Inactive Publication Date: 2005-09-07
SHELL INT RES MAATSCHAPPIJ BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For olefin oxides, conventional silver-based catalysts offer very low selectivities

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0030] The preparation of such catalysts is known in the art, and these known methods can be used in the present invention. The method of preparing the catalyst includes impregnating the support with silver compounds and other catalyst components, and reducing to form metallic silver particles. For example, reference may be made to US-A-4761394, US-A-4766105, US-A-5380697, US-A-5739075, US-B1-6368998, US-2002 / 0010094Al, WO-00 / 15333, WO-00 / 15334 and WO-00 / 15335, which documents are hereby incorporated by reference.

[0031] The invention can be applied to new catalysts, as well as to catalysts employed in epoxidation processes, or to catalysts which have undergone prolonged suspension due to plant shutdowns.

[0032] The invention is also applicable to catalyst precursors. The catalyst precursor refers to a supported composition comprising silver in its unreduced state, ie in cationic form, and this composition also contains the components necessary to obtain a highly select...

Embodiment 1-4

[0074] Embodiment 1-4 (embodiment 1 is used for comparing, and embodiment 2-4 is the present invention)

[0075] Preparation of vector

[0076] Prepare the vehicle by mixing the following components:

[0077] 1.67.4 parts by weight (pbw)d 50 α-alumina of 29 μm;

[0078] 2.29pbw d 50 α-alumina of 3 μm;

[0079] 3.3 pbw alumina (in the form of boehmite);

[0080] 4.0.5 pbw silica (as ammonia stabilized silica sol); and

[0081] 5.0.1 pbw sodium oxide (in the form of sodium acetate)

[0082] The average particle size is referred to here as "d 50 ”, measured by a Horiba LA900 particle size analyzer, and represents the particle diameter when particles larger than the average particle size and particles smaller than the average particle size have equal spherical equivalent volumes. The method includes dispersing by ultrasonic treatment particles, thereby breaking the secondary particles into primary particles. This sonication is continued until no d 50 A further change in v...

Embodiment 5

[0104] Example 5-8 (embodiment 5 is used for comparison, and embodiment 6-8 is the present invention)

[0105] Four stainless steel U-tubes were loaded with crushed catalyst samples (1.5-2.0 g) of Examples 1-4. The tubes were immersed in a molten metal bath (heating medium) at 180°C, and the ends of each tube were connected to a gas flow system. The gas mixture is passed through the catalyst bed in a "single pass" operation. The weight of the catalyst applied and the flow rate of the inlet gas were adjusted so that the hourly space velocity of the gas was 6800 Nl / (l.h). The pressure of the inlet gas is 1550kPa absolute.

[0106] In Examples 6, 7 and 8, the catalyst was first preheated with a gas mixture of 17.5 vol% oxygen and 82.5 vol% nitrogen at 260° C. for 4, 12 and 24 hours, respectively. Then the temperature was lowered to 225°C, and the gas mixture was adjusted to contain 25v% ethylene, 7v% oxygen, 5v% carbon dioxide, 1.5ppmv ethyl chloride and the balance nitrogen....

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Abstract

A method for improving the selectivity of a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.19 g per m<2> surface area of the support, which method comprises - contacting the catalyst, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250 DEG C for a duration of up to 150 hours, and - subsequently decreasing the catalyst temperature to a value of at most 250 DEG C; and a process for the epoxidation of an olefin, which process comprises - contacting a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.19 g per m<2> surface area of the support, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250 DEG C for a duration of up to 150 hours, and - subsequently decreasing the catalyst temperature to a value of at most 250 DEG C and contacting the catalyst with the feed comprising the olefin and oxygen.

Description

technical field [0001] The present invention relates to a method of increasing the selectivity of highly selective epoxidation catalysts. The present invention also relates to a process for the epoxidation of olefins, which comprises the process described in the present invention. Background technique [0002] The catalytic epoxidation of olefins to the corresponding olefin oxides over supported silver catalysts has long been known. Conventional silver-based catalysts provide very low selectivities for olefin oxides. For example, when conventional catalysts are used in the epoxidation of ethylene, the selectivity to ethylene oxide, expressed as the fraction of ethylene converted, does not exceed the limit value of 6 / 7 or 85.7 mol%. This limit has therefore long been considered the theoretical maximum selectivity for this reaction, based on the stoichiometric coefficients of the following reaction equation: [0003] <chemistry num="001"> <chem file="03815308_cml...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/50B01J23/68B01J37/02B01J37/14C07D301/03B01J37/08C07D301/10
CPCB01J23/688B01J37/14B01J37/0213B01J23/50C07D301/10B01J23/68B01J37/08
Inventor J·R·洛克米耶尔D·赖纳塔R·C·耶茨
Owner SHELL INT RES MAATSCHAPPIJ BV
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