US 5,271,835 AGranted

Process for removal of trace polar contaminants from light olefin streams

AssigneeUop LLC

InventorsJayant K. Gorawara, Henry Rastelli, John Markovs

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Abstract

A process is disclosed for improving catalyst performance and yields in the manufacture of motor gasoline components. More particularly the process is directed to the removal of H.sub.2 S, sulfur compounds, trace amounts of acetonitrile or acetone or propionitrile from a hydrocarbon feedstock, comprising a C.sub.3 -C.sub.5 product fraction from a fluid catalytic cracking unit which may be used subsequently in an etherification process for the production of ethers such as MTBE and TAME and/or an alkylation process for the production of alkylate. The hydrocarbon feedstock is passed to an amine treating zone, a mercaptan sulfur removal zone and an adsorption zone for the removal of sulfur compounds, water and trace amounts of acetonitrile or acetone or propionitrile. The regeneration of the adsorption zone includes the contacting of the sorbent with a heated regenerant vapor stream. The spent regenerant vapor stream is condensed to provide a hydrocarbon phase and an aqueous phase. The trace amounts of the acetonitrile, acetone, and propionitrile are removed in the aqueous phase. The hydrocarbon phase is treated to remove sulfur compounds and can be recycled as the regenerant.

Claims18

Dependent claims

A process for the removal of sulfur compounds including H.sub.2 S, COS and mercaptan sulfur compounds, and a trace amount of polar compounds comprising acetonitrile or acetone or propionitrile from a hydrocarbon feedstream comprising a C.sub.3 -C.sub.5 product fraction from a fluid catalytic cracking unit comprising the following steps:

(a) contacting the hydrocarbon feedstream with an alkanolamine in an amine treating zone under H.sub.2 S and COS absorption conditions to provide an H.sub.2 S- and COS-depleted stream;
(b) contacting the H.sub.2 S- and COS-depleted stream with an alkaline scrubbing solution in a mercaptan absorption zone under mercaptan sulfur absorption conditions to produce a mercaptan-depleted stream;
(c) contacting the mercaptan-depleted stream with a polar compound selective adsorbent in an adsorption zone comprising an adsorbent bed containing said adsorbent at adsorption conditions effective to adsorb the trace amount of polar compounds and to produce a treated product stream essentially free of acetonitrile, acetone, and propionitrile;
(d) recovering the treated product stream;
(e) contacting the polar compound selective adsorbent in said adsorbent bed with a heated regenerant vapor stream at regeneration conditions to desorb said polar compounds and to provide a spent regenerant vapor stream;
(f) cooling and condensing the spent regenerant vapor stream to provide a hydrocarbon phase and an aqueous phase;
(g) removing the aqueous phase comprising said polar compounds;
and,
(h) passing said hydrocarbon phase to an H.sub.2 S removal zone to provide a treated hydrocarbon stream and admixing at least a portion of the treated hydrocarbon stream with the regenerant vapor stream.

6 more elements

An alkylation process for the removal of sulfur compounds including H.sub.2 S, COS and mercaptan sulfur compounds, and a trace amount of polar compounds comprising acetonitrile or acetone or propionitrile from a hydrocarbon feedstream comprising a C.sub.3 -C.sub.5 product fraction from a fluid catalytic cracking unit comprising the following steps:

(a) contacting the hydrocarbon feedstream with an alkanolamine solution in an amine treating zone under H.sub.2 S and COS absorption conditions to provide an H.sub.2 S- and COS-depleted stream;
(b) contacting the H.sub.2 S- and COS-depleted stream with an alkaline scrubbing solution in a mercaptan absorption zone under mercaptan sulfur absorption conditions to produce a mercaptan-depleted stream and a mercaptide-containing scrubbing solution and contacting said mercaptide-containing scrubbing solution with air or oxygen in the presence of an oxidation catalyst effective to regenerate the mercaptide-containing scrubbing solution;
(c) contacting the mercaptan-depleted stream with a polar compound selective adsorbent in an adsorption zone comprising an adsorbent bed containing said adsorbent at adsorption conditions effective to adsorb said polar compounds to produce a polar-compound-reduced stream;
(d) passing the polar-compound-reduced stream and an isoparaffin stream into an alkylation zone to produce an alkylate product;
(f) regenerating the polar compound selective adsorbent in the adsorption zone by contacting the polar compound selective adsorbent with said heated regenerant vapor stream at regeneration conditions to desorb said polar compounds and to provide a spent regenerant vapor stream;
(g) condensing said spent regenerant vapor stream and recovering a hydrocarbon vapor phase, a hydrocarbon liquid phase and an aqueous phase;
(h) recycling at least a portion of said hydrocarbon vapor phase to provide a portion of said regenerant vapor stream, recovering said hydrocarbon liquid phase and admixing said hydrocarbon liquid stream with said hydrocarbon feedstream;
and
(i) removing the aqueous phase comprising said polar compounds.

6 more elements

An etherification process for the removal of sulfur compounds including H.sub.2 S, COS and mercaptan sulfur compounds, and a trace amount of polar compounds comprising acetonitrile or acetone or propionitrile from a hydrocarbon feedstream comprising a C.sub.3 -C.sub.5 product fraction from a fluid catalytic cracking unit comprising the following steps:

(a) contacting the hydrocarbon feedstream with an alkanolamine solution in an amine treating zone under H.sub.2 S and COS absorption conditions to provide an H.sub.2 S- and COS-depleted stream;
(b) contacting the H.sub.2 S- and COS-depleted stream with an alkaline scrubbing solution in a mercaptan absorption zone under mercaptan sulfur absorption conditions to produce a mercaptan-depleted stream;
(c) contacting the mercaptan-depleted stream with a polar compound selective adsorbent in an adsorbent zone comprising an adsorbent bed containing said adsorbent at adsorption conditions effective to adsorb the trace amounts of said polar compounds to produce a polar-compound-reduced stream;
and
(d) passing the polar-compound-reduced stream and an alcohol stream into an etherification zone to produce an ether product;
(e) heating a regenerant stream selected from the group consisting of fuel gas, natural gas, nitrogen and hydrogen to provide a regenerant vapor stream;
(f) regenerating the polar compound selective adsorbent in the adsorption zone by contacting the polar compound selective adsorbent with said regenerant vapor stream at regeneration conditions to desorb said polar compounds and to provide a spent regenerant vapor stream;
(g) condensing said spent regenerant vapor stream and recovering a hydrocarbon phase and an aqueous phase and recycling said hydrocarbon phase to provide a portion of said regenerant vapor stream;
and,
(h) removing the aqueous phase comprising said polar compounds.

7 more elements

Dependencies are inferred from the claim text.