发明名称 |
PROCESS FOR TRANSITIONING BETWEEN INCOMPATIBLE CATALYSTS |
摘要 |
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. |
申请公布号 |
EP3149061(A1) |
申请公布日期 |
2017.04.05 |
申请号 |
EP20150725313 |
申请日期 |
2015.05.26 |
申请人 |
SABIC Global Technologies B.V. |
发明人 |
AL-ENAZI, Nayef |
分类号 |
C08F210/02;C08F2/34;C08F4/24;C08F4/656 |
主分类号 |
C08F210/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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