Epoxidation process using serially connected cascade of fixed bed reactors

A fixed bed reactor, epoxidation technology, applied in chemical instruments and methods, organic chemistry, chemical recovery, etc., can solve problems such as expensive catalysts

Inactive Publication Date: 2001-01-31
ARCO CHEM TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A deactivated catalyst can alternatively be replaced with fresh catalyst, but will have the same practical disadvantages as regeneration
Also, catalysts of this type tend to be relatively expensive, and it may be desirable to minimize the amount of fresh catalyst that needs to be supplied to the facility

Method used

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  • Epoxidation process using serially connected cascade of fixed bed reactors
  • Epoxidation process using serially connected cascade of fixed bed reactors

Examples

Experimental program
Comparison scheme
Effect test

Embodiment comparative example 1

[0035] A conventional multi-bed reaction vessel (1) is used, where as figure 1 As shown, five reactor beds (A, B, C, D, E) are stacked. Containers of this general type are described in more detail, for example, in U.S. Patent Nos. 2,271,646 and 2,322,366. The reactor bed was simultaneously loaded with a total of 65 Kg of a titania-coated silica heterogeneous catalyst freshly prepared as described in U.S. Patent No. 3,829,392. A feed comprising 286 Kg / hr of ethylbenzene oxide and 408 Kg / hr of propylene was introduced via line 2 to the bottom bed of the reaction vessel, maintained in the liquid phase by operating at a pressure of 800 psia. Oxidized ethylbenzene is obtained by conventional molecular oxygen oxidation of ethylbenzene as described in U.S. Patent No. 4,066,706, containing about 35% by weight ethylbenzene hydroperoxide.

[0036] At the beginning of the epoxidation cycle, the temperature of the feedstock was about 38°C, initially bypassing the heat exchanger attached...

Embodiment 2

[0045] According to the present invention, if figure 2 A row of 6 individual reaction vessels (A, B, C, D, E, F) is shown arranged. Only 5 reaction vessels are serially connected by lines and used in the conversion operation at any given time. figure 2shows the row of reactors in a given epoxidation cycle in which the feed stream is sent first through reactor A, then reactor B, then reactor C, then reactor D, and finally through reactor E, so that reactor F is not in operation. Each reaction vessel contained a fixed bed comprising 13 Kg of silica catalyst on top of titania. Each reaction vessel was separated by a valve to allow one vessel to be closed at a time for catalyst bed replacement. The feed composition and feed rate were the same as those used in Comparative Example 1. Using heat exchangers (HE-1, HE-2, HE-3, HE-4), the inlet temperature of the feed stream introduced into each catalyst bed was controlled so that the outlet temperature did not exceed 121°C. That...

Embodiment 3

[0053] In this example, the epoxidation process was performed in the same manner as described in Example 2, except that at the end of the epoxidation cycle, the first reaction vessel in the sequence (reactor A) was removed from operation and replaced with The idle reaction vessel (Reactor F) was replaced by fresh catalyst. As a result, the feed stream is introduced first into the reaction vessel series containing the most active catalyst rather than, as in Example 2, the reaction vessel containing the least active catalyst. In the next epoxidation cycle, the reactor sequence is thus F-B-C-D-E. In subsequent cycles, the reactor containing the least active catalyst is again removed from operation and the feedstream is passed first through the replacement reactor with the most active catalyst in the series, and thereafter through the remaining operating reactors in order of increasing catalyst activity. reactor. In the third cycle, the reactor sequence will be eg A-C-D-E-F, wit...

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PUM

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Abstract

An olefin epoxidation process is operated using a plurality of reactor vessels, each containing a fixed bed of a heterogenous catalyst such as titania-on-silica. The reactor vessels are connected in series whereby a feedstream comprised of olefin and an active oxygen species is passed through said series of reactor vessels in contact with the heterogenous catalyst to accomplish conversion of the olefin to the corresponding epoxide. As the activity of the catalyst in an individual reactor vessel falls to an undesirably low level, said reactor vessel is taken out of service and a replacement reactor containing fresh or regenerated catalyst introduced. The replacement reactor vessel may, in alternative embodiments of the process, be the first or the last reactor vessel in said series. For example, the feedstream may first be contacted with either the most active or the least active charge of catalyst within the series of reactor vessels. Although the latter embodiment permits somewhat longer catalyst life, the former embodiment requires much smaller capacity heat exchangers. The process of this invention considerably reduces catalyst usage as compared to a conventional fixed bed epoxidation process where all of the catalyst is replaced or regenerated at the same time.

Description

field of invention [0001] The present invention provides a method of operating an epoxidation plant using a heterogeneous catalyst which makes it possible to significantly extend the lifetime of said catalyst. More particularly, the invention relates to a cascade of continuously connected fixed bed reactors in which a single reactor is periodically taken offline for catalyst regeneration or replacement when catalyst activity has dropped to an undesirable level; The catalyst reactor was brought into use so that the epoxidation proceeded without interruption. A feedstream containing olefins and reactive oxygen species is continuously fed through the reactor cascade, ideally with the aid of heat exchangers to control the temperature of the exothermic process to maintain high epoxidation selectivity. In one embodiment, the feedstream is contacted with the most active catalyst in the series first. In another embodiment, the feedstream is contacted with the least active catalyst f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D301/14C07D301/04C07D301/06C07D301/12C07D301/19
CPCC07D301/12C07D301/06C07D301/19Y02P20/584B01J8/0496B01J29/89C07D303/04
Inventor 小·J·C·朱宾J·B·丹纳
Owner ARCO CHEM TECH INC
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