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Processing C4 olefin streams for the maximum production of propylene

A technology for olefin materials and streams, which can be used in chemical instruments and methods, sustainable manufacturing/processing, chemical industry, etc., and can solve problems such as loss of propylene production

Inactive Publication Date: 2006-10-25
ABB LUMMUS GLOBAL INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the presence of these olefins affects the required size of the equipment, they do not constitute a potential loss of propylene production

Method used

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  • Processing C4 olefin streams for the maximum production of propylene
  • Processing C4 olefin streams for the maximum production of propylene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] Conventional treatment with high ethylene content

[0055] In this case, 2750 kg / hr of fresh ethylene was utilized for a n-butene flow of 6651 kg / hr. This is 0.41 weight ratio or 0.85 fresh feed mole ratio. The material balances are summarized in Table B.

[0056] Step 1: First put C 4 The feed is sent to catalytic distillation DIB column 14 where 9054 kg / hr of isobutene and isobutane are removed as overhead product 16 . Bottom product 18 (9570 kg / hr) is a stream of substantially pure 2-butene mixed with paraffins.

[0057] Step 2: Bottoms stream 18 with fresh ethylene 19 and recycled ethylene from deethanizer 24 with 4 The combined recycles 34 of the fractionation system 30 (after venting 36 ) are mixed and fed to the metathesis unit 22 . The metathesis unit contains metathesis and double bond isomerization catalysts. With a one-pass n-butene conversion of 59%, the molar selectivity to propylene was 99%. Selectivity is defined as the number of moles of propylene...

Embodiment 2

[0064] Regular Moderate Ethylene

[0065] In a second example, half the ethylene was available (1375 kg / hr fresh ethylene). This represents an ethylene to n-butene ratio of 0.21 weight fraction or 0.43 mole fraction. The material balances are summarized in Table C.

[0066] Step 1: This is the same as Example 1, for a conventional metathesis unit, yielding a feed of 9570 kg / hr (18,624 minus 9054).

[0067] Step 2: Selectivity to propylene decreases due to reduction of ethylene. The molar selectivity dropped from 99% to 88.8%. Under these conditions, ethylene conversion was higher (66% versus 40%) and butene conversion was lower (36.5 versus 59).

[0068] Step 3: Recovery and recycling of ethylene.

[0069] Step 4: Recover propylene. Propylene production decreased from 8164 kg / hr to 5110 kg / hr due to lower ethylene flow. 37% lower.

[0070] Step 5: Unreacted C 4 with most of the C produced by the lower selectivity reaction 5 recycle together. The combination of lower...

Embodiment 3

[0073] Regular Low Ethylene

[0074] In this final example for the conventional case, the fresh ethylene is almost zero (590 kg / hr). This represents a fresh ethylene / n-butenes ratio of 0.08 by weight or 0.18 by mole. The material balances are summarized in Table D.

[0075] Step 1: This is the same, for a conventional metathesis unit, a feed of 9570 kg / hr is produced.

[0076] Step 2: Selectivity to propylene is worse due to further reduction of ethylene. The overall molar selectivity dropped from 88.8% to 76.8%. This is equivalent to C 4 57.6% selectivity. Under these conditions, butene conversion was essentially the same (37.3 vs. 36.5 in Example 2).

[0077] Step 3: Recovery and recycling of ethylene. Due to the low level of fresh ethylene, this flow is very small.

[0078] Step 4: Recover propylene. Propylene production decreased from 5110 kg / hr to 3521 kg / hr due to very low ethylene flow. This is only 43% of the yield of Example 1.

[0079] Step 5: Unreacted C ...

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Abstract

In order to maximize the production of propylene when the external supply of ethylene is limited, the C4 cut from a hydrocarbon cracking process is first subjected to autometathesis prior to any isobutylene removal and without any ethylene addition. This favors the reactions which produce propylene and pentenes. The ethylene and propylene produced are then removed leaving a stream of the C4's and heavier components. The C5 and heavier components are then removed leaving a mixture of 1-butene, 2-butene, isobutylene, and iso-and normal butanes. The isobutylene is next removed preferably by a catalytic distillation hydroisomerization de-isobutyleneizer. The isobutylene-free C4 stream is then mixed with the product ethylene removed from the autometathesis product together with any fresh external ethylene needed and subjected to conventional metathesis producing additional propylene.

Description

technical field [0001] The present invention relates to compounds from cracking processes, such as steam or fluid catalytic cracking, mainly for the conversion of C 4 Process C for the conversion of olefins to propylene 3 -C 6 Methods of processing hydrocarbon fractions. Background technique [0002] In a typical olefins plant, there is a front-end demethanizer for the removal of methane and hydrogen and a subsequent demethanizer for the removal of ethane, ethylene and C 2 Acetylene deethanizer. The bottom fraction of the deethanizer is composed of C 3 -C 6 A mixture of compounds with a carbon number. This mixture is usually separated into different carbon numbers by fractional distillation. [0003] C 3 Fractions, mainly propylene, are removed as products and are ultimately used in the production of polypropylene or chemical synthesis such as propylene oxide, cumene or acrylonitrile. Methylacetylene and propadiene (MAPD) ​​impurities must be removed by fractional d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C6/04C07C11/06
CPCC07C6/04C07C11/06C07C2521/08C07C2521/10C07C2523/30Y02P20/10
Inventor R·J·加特赛德M·I·格林
Owner ABB LUMMUS GLOBAL INC
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