Separation of C4 olefins

Claim 2

In a process for separating isobutylene from a feed containing isobutylene and at least one normal C 4 hydrocarbon comprising contacting said feed at retention conditions with a molecular sieve comprising silicalite to effect selective retention of said normal C 4 hydrocarbon, removing said isobutylene from contact with said molecular sieve, and recovering said normal C 4 hydrocarbon by displacement from said molecular sieve, the improvement which comprises performing said displacement with a displacement fluid consisting essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve at displacement conditions.

Claim 3

The process of claim 1 wherein said retention conditions include a temperature within the range of from about 20° C. to about 200° C. and a pressure sufficient to maintain liquid phase.

Claim 4

The process of claim 1 wherein said displacement conditions include a temperature range within the range of from about 20° C. to about 200° C. and a pressure sufficient to maintain liquid phase.

Claim 5

The process of claim 1 wherein said displacement fluid contains from about 10 to about 90 LV% pentene-1.

Claim 6

The process of claim 1 wherein said diluent comprises isooctane or cyclohexane.

Claim 7

The process of claim 1 wherein said normal C 4 hydrocarbon comprises an olefin.

Claim 8

The process of claim 1 wherein said molecular sieve comprises silicalite bound with an inorganic oxide.

Claim 9

The process of claim 1 wherein said molecular sieve comprises silicalite bound with a fluid permeable organic polymer.

Claim 10

The process of claim 8 wherein said fluid permeable organic polymer comprises polystyrenedivinylbenzene.

Claim 11

A process for separating isobutylene from a feed containing isobutylene and at least one normal C 4 hydrocarbon using a molecular sieve comprising silicalite, which process comprises the steps of: (a) maintaining net fluid flow through a column of said molecular sieve in a single direction, which column contains at least three separate and serially interconected zones; (b) maintaining a retention zone defined by the feed inlet and raffinate outlet as a downstream boundary; (c) maintaining a purification zone defined by an extract outlet and said feed inlet as a downstream boundary; (d) maintaining a displacement zone defined by a displacement fluid inlet and said extract outlet as a downstream boundary; (e) passing said feed into said retention zone at retention conditions and retaining said normal C 4 hydrocarbon and withdrawing a raffinate stream containing isobutylene; (f) passing a displacement material consisting essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve into said displacement zone at displacement conditions and displacing said normal C 4 hydrocarbon from said molecular sieve; (g) withdrawing an extract stream comprising said normal C 4 hydrocarbon and displacement fluid consisting essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve from said displacement zone; and, (h) periodically advancing through said column of molecular sieve in a downstream direction with respect to fluid flow said feed inlet, raffinate outlet, displacement fluid inlet, and extract outlet to shift zones through said molecular sieve.

Claim 12

A process for separating isobutylene from a feed containing isobutylene and at least one normal C 4 hydrocarbon using a molecular sieve comprising silicalite, which process comprises the steps of: (a) maintaining net fluid flow through a column of said molecular sieve in a single direction, which column contains at least three separate and serially interconected zones; (b) maintaining a retention zone defined by the feed inlet and raffinate outlet as a downstream boundary; (c) maintaining a purification zone defined by an extract outlet and said feed inlet as a downstream boundary; (d) maintaining a displacement zone defined by a displacement fluid inlet and said extract outlet as a downstream boundary; (e) passing said feed into said retention zone at retention conditions and retaining said normal C 4 hydrocarbon and withdrawing a raffinate stream containing isobutylene; (f) passing a displacement material consisting essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve into said displacement zone at displacement conditions and displacing said normal C 4 hydrocarbon from said molecular sieve; (g) withdrawing an extract stream comprising said normal C 4 hydrocarbon and displacement fluid consisting essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve from said displacement zone; and, (h) periodically advancing through said column of molecular sieve in a downstream direction with respect to fluid flow said feed inlet, raffinate outlet, displacement fluid inlet, and extract outlet to shift zones through said molecular sieve.

Claim 13

The process of claim 10 wherein said raffinate stream is passed to a separation means wherein said displacement fluid consists essentially of pentene-1 in solution with a diluent not selectively retained by said molecular sieve is removed from said stream to produce substantially pure isobutylene product.

Claim 14

The process of claim 11 wherein a buffer zone is maintained immediately upstream from said displacement zone, said buffer zone defined as the molecular sieve located between the displacement fluid inlet in a downstream boundary of said buffer zone and a raffinate outlet at an upstream boundary of said buffer zone.

Claim 15

The process of claim 10 wherein said retention and displacement conditions include a temperature within the range of from about 20° C. to about 200° C. and a pressure sufficient to maintain liquid phase.

Claim 16

The process of claim 10 wherein said displacement fluid contains from about 10 to about 90 LV% pentene-1.

Claim 17

The process of claim 10 wherein said diluent comprises iso-octane or cyclohexane.

Claim 18

The process of claim 10 wherein said molecular sieve comprises silicalite bound with inorganic oxide.

Claim 19

The process of claim 10 wherein said molecular sieve comprises silicalite bound with a fluid permeable organic polymer.

Claim 20

The process of claim 17 wherein said fluid permeable organic polymer comprises polystyrenedivinylbenzene.