EP2094628A2 - Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation - Google Patents

Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation

Info

Publication number
EP2094628A2
EP2094628A2 EP07822664A EP07822664A EP2094628A2 EP 2094628 A2 EP2094628 A2 EP 2094628A2 EP 07822664 A EP07822664 A EP 07822664A EP 07822664 A EP07822664 A EP 07822664A EP 2094628 A2 EP2094628 A2 EP 2094628A2
Authority
EP
European Patent Office
Prior art keywords
dehydrogenation
catalyst
oxidation
hydrogen
reaction gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07822664A
Other languages
German (de)
English (en)
Inventor
Christophe Houssin
Gerald Vorberg
Christian Walsdorff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Priority to EP07822664A priority Critical patent/EP2094628A2/fr
Publication of EP2094628A2 publication Critical patent/EP2094628A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
    • C07C15/40—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals
    • C07C15/42—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic
    • C07C15/44—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts substituted by unsaturated carbon radicals monocyclic the hydrocarbon substituent containing a carbon-to-carbon double bond
    • C07C15/46—Styrene; Ring-alkylated styrenes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/42—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with a hydrogen acceptor
    • C07C5/48—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with a hydrogen acceptor with oxygen as an acceptor

Definitions

  • the present invention relates to an improved process for the production of styrene by dehydrogenation of ethylbenzene.
  • the production of styrene by dehydrogenation of ethylbenzene is usually carried out by mixing ethylbenzene with steam and introducing this mixture into a fixed bed reactor equipped with dehydrogenation catalysts. Since the dehydrogenation reaction of ethylbenzene is endothermic, the temperature decreases with the progress of the reaction and thus slows the reaction rate. In addition, as the reaction proceeds, the content of hydrogen increases, and a high content of hydrogen adversely affects the dehydrogenation reaction and further slows the reaction rate as the reaction progresses.
  • a gas mixture having a reduced amount of hydrogen is obtained, which further has a high temperature by the combustion reaction, so that the subsequent dehydrogenation process can be carried out at a high reaction rate.
  • EP-A 1 229 011 this problem is solved, in which hydrogen is fed to the reaction mixture leaving the oxidation step. It is described that the molar ratio of hydrogen to Sytrol when entering the second dehydrogenation reactor is advantageously between 0.9 and 1.3. Furthermore, it is recommended in EP-A 1 229 01 1 to use a styrene catalyst with a reduced potassium catalysis rate in the inlet area of the second dehydrogenation step. In the case that different Dehydrierkatalysa- If the less active catalyst is used upstream and the comparatively more active catalyst downstream.
  • EP-A 1 229 01 1 A disadvantage of the solution of EP-A 1 229 01 1 is that due to the increased amount of hydrogen in the second dehydrogenation step, the conversion in this step is adversely affected.
  • Another problem with the described dehydrogenation process with combined oxidation is that in addition to hydrogen, the product styrene and the starting material ethylbenzene are burned in the oxidation step, so that on the one hand the yield of styrene is adversely affected and on the other the desired energy input from the hydrogen combustion lower fails.
  • the object of the present invention was therefore to show a more efficient process for the production of styrene, which overcomes the disadvantages of the prior art.
  • the molar ratio of hydrogen to ethylbenzene after the first step (i) is greater than 0.45, preferably greater than 0.5, in particular greater than 0.55.
  • the high molar ratio of hydrogen to ethylbenzene compared to the prior art can be achieved by using a very active dehydrogenation catalyst in the first dehydrogenation step (i).
  • the high molar ratio can also be achieved by additional supply of hydrogen before the oxidation step.
  • the hydrogen is supplied at the end of the first dehydrogenation step, between the first dehydrogenation step and the oxidation step and / or at the beginning of the oxidation step.
  • the molar ratio is achieved by the use of a very active dehydrogenation catalyst in the first dehydrogenation step (i).
  • Very active dehydrogenation catalysts can advantageously be operated at a low reaction temperature as very selective dehydrogenation catalysts. This high activity is generally achieved at the expense of selectivity. By contrast, very selective dehydrogenation catalysts require comparatively higher reaction temperatures. The higher selectivity is generally achieved at the expense of activity.
  • the value of the "activity” is determined by the molar conversion of ethylbenzene.
  • the value of "selectivity” is determined by the molar conversion of ethylbenzene to styrene.
  • the performance of catalysts is given, for example, in the form of a "temperature parameter” and a "selectivity parameter".
  • the temperature parameter is understood to mean the temperature at which a catalyst reaches a conversion of ethylbenzene of 65%, the selectivity parameter describing the selectivity achieved at this temperature. Accordingly, the temperature parameter is the lower, the more active the respective catalyst is. The selectivity parameter is the higher the higher the selectivity.
  • the dehydrogenation catalysts are generally iron oxide-containing catalysts, as described, for example, in DE-A 101 54 718.
  • the dehydrogenation catalyst In order to influence the catalyst activity / catalyst selectivity, the dehydrogenation catalyst usually has other components in addition to the iron oxide.
  • the manner of increasing the activity or selectivity is generally known to the person skilled in the art and described, for example, in WO 2004/769 on pages 8 to 10 and pages 14 to 15.
  • Other known components are, for example, lanthanides, in particular cerium; Molybdenum, copper and / or chromium; Alkali metals, in particular potassium and / or cesium; Alkaline earth metals, in particular magnesium and / or calcium around; or optionally further component, in particular manganese, zinc, titanium, vanadium and / or tungsten.
  • high activity, high selectivity dehydrogenation catalysts may differ in one or more component aspects, such as the source, choice, and amount of single or multiple dopant components.
  • the dehydrogenation catalysts may also differ in their surface structure, for example in the BET surface area, in the pore size or in the pore volume.
  • the average pore diameter of the more selective catalyst is greater than the average pore diameter of the more active catalyst.
  • the dehydrogenation in the first step (i) to be used dehydrogenation catalyst has a temperature parameter 570 to 655 ° C, preferably 580-645 ° C, in particular 605-640 0 C.
  • the method of preparation of the dehydrogenation catalysts is likewise generally known to the person skilled in the art and described, for example, in WO 2004/769 on pages 10 to 12.
  • the dehydrogenation catalysts are usually used in the form of solid cylinders, star strands or gear-shaped strands, as described for example in EP-A 1 027 928 or EP-A 423 694.
  • the dehydrogenation reaction can be carried out by all methods known to those skilled in the art, for example as described in WO 2005/97715, page 5, lines 17 to 35.
  • the inlet temperature into the first dehydrogenation reactor is thus advantageously at 570-655 ° C, preferably 580-645 ° C, in particular 605-640 0 C.
  • the ethylbenzene fed to the first dehydrogenation step is advantageously mixed with water vapor.
  • the molar ratio of water vapor to ethylbenzene is usually between 1 and 15, preferably between 1 and 10.
  • two or more dehydrogenation steps are connected in series.
  • some dehydrogenation steps may be parallel.
  • tion step advantageously there is an oxidation step at least between the first and the second dehydrogenation step.
  • the process according to the invention preferably has three dehydrogenation steps, an oxidation step being integrated between the first and the second dehydrogenation step and optionally an oxidation step between the second and the third dehydrogenation step.
  • fixed bed reactors or radial reactors can be used as dehydrogenation reactors or as oxidation reactors.
  • the stages (ii) and (iii) and, if appropriate, further combined oxidation and dehydrogenation steps are combined in one reactor each.
  • the catalysts are arranged so that the reaction gas flows through first the oxidation catalysts and then the dehydrogenation catalysts. Preference is given to using radial flow reactors in which the catalyst beds of oxidation and dehydrogenation catalysts are arranged concentrically with one another and optionally separated from one another by cylindrical sieves. The oxidation catalyst is then used as the inner of the two concentrically arranged approximately hollow cylindrical beds.
  • the volume ratio of the beds of oxidation catalyst and dehydrogenation catalyst per reactor is generally 0.1: 1 to 1: 1, preferably 0.15: 1 to 0.6: 1, in particular 0.2: 1 to 0.4: 1.
  • step (i) the first dehydrogenation step, there is a potassium trap well known to those skilled in the art.
  • oxidation process can be carried out by all methods known to the person skilled in the art, for example as described in WO 2005/97715, page 4, lines 1 to 15 and page 5, line 37 to page 6, line 5.
  • nitrogen is also added to the reaction gas from stage (i).
  • the molar ratio of oxygen to nitrogen is advantageously less than 25%.
  • Oxidation catalysts which can be used are all oxidation catalysts known to the person skilled in the art, for example noble metal catalysts as in WO
  • a catalyst is used as the oxidation catalyst, which, supported on substantially ⁇ -alumina, 0.01 to 0.1 wt .-% of platinum and 0.01 to 0.1 wt .-% tin, based on the total weight of the catalyst contains.
  • the oxidation catalysts can be prepared by all preparation processes known to those skilled in the art, as described, for example, in WO 2005/97715, in EP-A 826 418 or in US Pat. No. 6,280,608.
  • the application of the active components of the catalyst by impregnation.
  • the hydrogen selectivity in the oxidation reaction is advantageously greater than 70%, preferably greater than 80%, in particular greater than 85%, measured at the beginning of the two to three-year runtime of the process according to the invention.
  • the reaction temperature is when it enters the second dehydrogenation step (step iii) 580 to 655 ° C, preferably 590-650 0 C, in particular 610-645 ° C.
  • the catalyst in the first dehydrogenation step (i), it is advantageous to use a catalyst which has a lower temperature parameter (T) than the second dehydrogenation step (iii). Further, in the first dehydrogenation step (i), the catalyst has a lower selectivity parameter (S) compared to the second dehydrogenation step (iii) (TA ⁇ TB and SA ⁇ SB).
  • a catalyst which has a higher temperature parameter (T) and a higher selectivity parameter (S) (TA ⁇ TB and SA ⁇
  • the catalyst has in the first dehydrogenation step (i) a temperature parameter on which, preferably at least 5 ° C, more preferably at least 10 0 C, in particular at least 20 0 C is lower by at least 1 ° C than the temperature parameter the catalyst of the second dehydrogenation step (iii).
  • catalysts in the second dehydrogenation step (iii) may be used which may be partial or complete
  • secondary catalyst material Use of secondary catalyst material have been prepared, as described in the international application with the file number PCT / EP2006 / 064178.
  • the term "secondary catalyst material" is understood in the present invention to be used / used / deactivated, optionally treated catalyst material.
  • Catalysts containing a mixture of 10 to 70 wt .-% ground, optionally calcined at 100 to 1500 ° C secondary catalyst material of a used (de) hydrogenation catalyst containing iron oxide and 30 to 90 wt .-% of the corresponding fresh are advantageously used in the second dehydrogenation step
  • reaction mixture is advantageously brought to the desired temperatures via a heat exchanger by means of, for example, superheated steam before entering the third or further dehydrogenation step.
  • the process according to the invention has the advantage that styrene can be produced with a higher yield. Furthermore, the drop in yield which can be determined over a longer period of the described process can be reduced.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

L'invention concerne un procédé pour produire du styrène par déshydrogénation d'éthyle benzène, comprenant les étapes (i) à (iii): (i) dans une première étape de déshydrogénation, un mélange gazeux contenant de l'éthyle benzène et éventuellement de la vapeur d'eau est mis en contact avec un premier catalyseur de déshydrogénation (A), ce qui entraîne la production d'un gaz de réaction contenant de l'éthyle benzène, du styrène et de l'hydrogène; (ii) dans une étape d'oxydation, le gaz de réaction obtenu dans la première étape est mis en contact avec de l'oxygène en présence d'un catalyseur d'oxydation, l'hydrogène étant au moins partiellement brûlé; (iii) dans une seconde étape de déshydrogénation, le gaz de réaction obtenu dans l'étape d'oxydation est mis en contact avec un second catalyseur de déshydrogénation (B), qui est caractérisé en ce que le rapport molaire de l'hydrogène par rapport à l'éthyle benzène dans le gaz de réaction obtenu dans la première étape de déshydrogénation est supérieur à 0,4.
EP07822664A 2006-11-20 2007-11-16 Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation Withdrawn EP2094628A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP07822664A EP2094628A2 (fr) 2006-11-20 2007-11-16 Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP06124421 2006-11-20
EP07822664A EP2094628A2 (fr) 2006-11-20 2007-11-16 Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation
PCT/EP2007/062445 WO2008061938A2 (fr) 2006-11-20 2007-11-16 Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation

Publications (1)

Publication Number Publication Date
EP2094628A2 true EP2094628A2 (fr) 2009-09-02

Family

ID=39083239

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07822664A Withdrawn EP2094628A2 (fr) 2006-11-20 2007-11-16 Procédé pour déshydrogéner des hydrocarbures, comportant des étapes de déshydrogénation et d'oxydation

Country Status (4)

Country Link
EP (1) EP2094628A2 (fr)
KR (1) KR20090082216A (fr)
CA (1) CA2668032A1 (fr)
WO (1) WO2008061938A2 (fr)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4565898A (en) * 1985-03-06 1986-01-21 Uop Inc. Dehydrogenation of dehydrogenatable hydrocarbons
CA2387715C (fr) * 2000-08-18 2009-03-24 Mitsubishi Chemical Corporation Procede de production de styrene

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008061938A2 *

Also Published As

Publication number Publication date
WO2008061938A2 (fr) 2008-05-29
WO2008061938A3 (fr) 2008-08-28
KR20090082216A (ko) 2009-07-29
CA2668032A1 (fr) 2008-05-29

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