Gasoline cracking
AssigneeShell Oil Company
InventorsGeorge A. Hadjigeorge, Colin John Schaverien, Nicolaas Wilhelmus Joseph Waij
Life of this patent
Estimating the term…
Abstract
Process for the preparation of C3 and C4 olefins and gasoline by: (a) contacting in a fluidised bed reactor a light hydrocarbon feedstock with a first catalyst inventory comprising a medium pore size zeolite catalyst, wherein the first catalyst inventory is a fresh catalyst inventory; (b) combining at least part of the catalyst inventory as used in step (a) with one or more catalyst streams to form a second catalyst inventory comprising a medium pore size zeolite catalyst and a large pore size zeolite catalyst; (c) contacting a hydrocarbon feedstock with the second catalyst inventory in a reactor riser to form cracked products.
Claims25
A process for the preparation of C3 and/or C4 olefins by:
- (a) contacting in a dense fluidised bed system a light hydrocarbon feedstock with a first catalyst inventory comprising up to an amount of 30 wt % large pore zeolite catalyst and more than 70 wt % based on the total mass of the catalyst inventory of a medium pore size zeolite catalyst, at least 50% of which is fresh medium pore size zeolite catalyst, wherein said dense fluidised bed system has a catalyst density of between 300 and 800 kg/m3, and wherein said dense fluidised bed system is operated under first reaction conditions including a first temperature in the range of from 400 to 700° C., a first pressure in the range of from 0.3 to 10 bar absolute, a first weight hourly space velocity (WHSV) in the range of from 5 to 50 hr−1, and wherein the weight ratio of said first catalyst inventory to said light hydrocarbon feedstock is in the range of from 1:1 to 20:1, to thereby form a cracked product stream comprising at least one of C3 and C4 olefins;
- (b) combining at least part of the first catalyst inventory as used in step (a) with an equilibrium catalyst, a fresh catalyst and a regenerated catalyst to form a second catalyst inventory comprising medium pore size zeolite catalyst and large pore size zeolite catalyst;
- and
- (c) contacting a hydrocarbon feedstock with the second catalyst inventory in a riser reactor to form a second cracked product stream, wherein the catalyst density of said dense fluidised bed system is higher than the catalyst density in said riser reactor, and wherein said riser reactor is operated under second reaction conditions including a second temperature in the range of from 400 to 700° C., a second pressure in the range of from 1 to 10 bar absolute, and a vapor residence time in the range of from 0.1 to 10 seconds.
A method for improving the propylene productivity of a fluid catalytic cracking unit, which unit produces cracked products from a hydrocarbon feedstock, said unit comprising a riser reactor for catalytically cracking the hydrocarbon feedstock, a separator vessel, a stripper, a regenerator, a distiller and a catalyst inventory comprising a large pore size zeolite catalyst said method comprising:
- (a) adding a dense fluidised bed system to said unit, said dense fluidised bed system having a catalyst density higher than the catalyst density of the catalyst in said riser reactor;
- (b) adding a first catalyst inventory comprising up to an amount of 30 wt % large pore zeolite catalyst and more than 70 wt % of a medium pore size zeolite catalyst, based on the total mass of the catalyst inventory, to the dense fluidised bed system;
- (c) combining at least part of the first catalyst inventory as used in step (a) with an equilibrium catalyst, a fresh catalyst and a regenerated catalyst to form a second catalyst inventory comprising medium pore size zeolite catalyst and large pore size zeolite catalyst;
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- (d) contacting a hydrocarbon feedstock with the second catalyst inventory in a riser reactor to form a second cracked product stream, wherein the catalyst density of said dense fluidised bed system is higher than the catalyst density in said riser reactor, and wherein said riser reactor is operated under second reaction conditions including a second temperature in the range of from 400 to 700° C., a second pressure in the range of from 1 to 10 bar absolute, and a vapor residence time in the range of from 0.1 to 10 seconds.
Dependencies are inferred from the claim text.