[12] Patent
[11] Patent No.:GC0009384  
[45] Date of Publishing the Grant of the Patent: 31/Dec /2018                56/2018  
Number of the Decision to Grant the Patent:2018/141744
Date of the Decision to Grant the Patent:17/Dec/2018

[21] Application No.:GC 2015-29457

[22] Filing Date:26/5/2015

[30] Priority:

[33] State [32] Priority date [31] Priority No.
EP
US
27/5/2014
14/5/2015
14170018.7
62/161,400

[72] Inventor: AL-ENAZI, Nayef

[73] Owner: SABIC Global Technologies B.V., Plasticslaan 1, 4612, Bergen op Zoom, Netherlands

[74] Agent: Saba & Co. T.M.P

  

 

  

[51]IPC:
Int. Cl.: C08F 2/34, 210/02, 4/24, 4/656 (2006.01)

[56] Cited Documents:

-US 2004143076 A1 (TERRY KERSTEN ANNE [US] ET AL) 22 JuIy 2004
-US 2003114609 A1 (SAMSON JOHN NORMAN REID [GB]) 19 June 2003
-WO 0058377 A1 (CHEVRON CHEM CO [US]; BYBEE WILLIAM D [US]; KRUTILEK MITCHELL A [US];) 5 October 2000
 
Examiner: Rami Al-Ghamdi

[54] PROCESS FOR TRANSITIONING BETWEEN INCOMPATIBLE CATALYSTS
[57] Abstract: The invention relates to a process for transitioning from a first contiunuous polymerization reaction of ethylene and a first comonomer for producing a linear low density polyethylene conducted in the presence of a Ziegler-Natta catalyst in a gas phase reactor to a second contiunuous polymerization reaction of ethylene and a second comonomer for producing a high density polyethylene conducted in the presence of a chromium-based catalyst in the gas phase reactor, the process comprising: (i) reducing the feed of the first comonomer into the reactor until the ratio of the first comonomer to ethylene in the reactor is at most 0.1; (ii) discontinuing the introduction of the Ziegler-Natta catalyst while the introduction of a co-catalyst of the Ziegler-Natta catalyst is continued and subsequently discontinuing the introduction of the co-catalyst;(iii) maintaining the polymerization conditions in the reactor and permitting polymerization to continue for a time in order to allow the components of the Ziegler-Natta catalyst present in the reactor to consume themselves in the production of additional polymer;(iv) discontinuing the introduction of all feeds into the reactor; (v) depressurizing the reactor;(vi) flow-purging the reactor;(vii) reducing the reactor temperature;(viii) introducing ethylene and H2 into the reactor to obtain a partial pressure of ethylene and a volume ratio of H2 to ethylene for the second polymerization reaction, wherein the partial pressure of ethylene is increased to the pressure for the second polymerization reaction at such a speed that the reactor temperature is maintained at a temperature lower than the temperature of the first polymerization conditions;(ix) increasing the reactor temperature to a temperature of the second polymerization conditions;(x) introducing the second catalyst into the reactor and(xi) introducing the second comonomer into the reactor to obtain a reactor composition for the second polymerization reaction.
No. of claims: 13     No. of figures: 2


 

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