Ethylene

butene-1

To produce butene-1 from ethykene by selectived dimerization using the Alphabutol process.

Description: Polymerization-grade ethylene vapor is fed to the reactor (1). The dimerization reaction occurs on the liquid phase because a specific catalyst is continuously metered into the reactor solution.
   The heat of reaction is removed by a pumparound system using either an air or water cooler (2). The spent catalyst, withdrawn with the product from the bottom of the reactor, is separated in a catalyst removal section (3) and sent to disposal,e.g., incineration. The hydrocarbons are sent to the fractionation section (4,5) where the unconverted ethylene is separated (4) and recycled to the reactor. In the next separation (5), pure butene-1 is obtained overhead and oligomers (predominantly C6 olefins) are a bottom product. A stream from this vessel is used for catalyst preparation (6).

Yields: Butene-1 at 30,000 tpy and gasoline at 2,250 tpy are made from 32,250 tpy ethylene. Byproduct C4s, ppmw:

Butene-2, cis + trans
Isobutene
Butadiene, 1-3 + 1-2     
Butane, n + iso
Acetylenics

<200
<5
<5
<1,500
<5

There are no polar products from the catalytic system, therefore, the polar impurities are those of the feed and each should be less than 2 ppmw. The concentration of ethylene (<1 wt% ) and hexene (<0,1 wt% ) may be adjusted by distillation.