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US 6,191,331 B1Granted
Zeolite catalyst precoking method for selective aromatics disproportionation process
AssigneeUop LLC
InventorEdwin P. Boldingh
Life of this patent
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Abstract
An improved process is disclosed for the selective disproportionation of toluene. The process uses a zeolitic catalyst which is selectively precoked prior to toluene disproportionation in a manner to avoid a large temperature rise across a bed of the catalyst during precoking. The catalyst and process provide enhanced selectivity for the production of paraxylene.
Claims19
A process for the production of paraxylene comprising the steps of:
- (a) selectively precoking a zeolitic catalyst in a catalyst bed by contacting the catalyst with a coke-forming feed at precoking conditions comprising an inlet temperature of from about 300° to about 700° C. and a temperature differential across the bed of the catalyst of between a 3° C. increase and a 4° C. decrease to deposit between about 5 and 40 mass-% carbon on the catalyst and obtain a selectively precoked catalyst;
- and,
- (b) disproportionating an aromatics-rich feedstock comprising contacting the feedstock with the selectively precoked catalyst bed in a disproportionation zone at disproportionation conditions to obtain a paraxylene-rich product containing paraxylene in excess of its equilibrium concentration at disproportionation conditions.
A process for the production of paraxylene comprising the steps of:
- (a) selectively precoking a zeolitic catalyst in a catalyst bed by contacting the catalyst with a coke-forming feed at precoking conditions comprising an inlet temperature of from about 300° to about 700° C., a pressure of from about 100 kPa to 4 MPa absolute, a liquid hourly space velocity of from about 0.2 to 10 hr−1, a molar ratio of free hydrogen to feedstock hydrocarbons of about 0.2 to 5 and a temperature differential across the bed of the catalyst of between a 3° C. increase and a 4° C. decrease to deposit between about 5 and 40 mass-% carbon on the catalyst and obtain a selectively precoked catalyst;
- and,
- (b) disproportionating an aromatics-rich feedstock comprising contacting the feedstock with the selectively precoked catalyst bed in a disproportionation zone at disproportionation conditions comprising an inlet temperature of from about 200° to about 600° C., a pressure of from about 100 kPa to 6 MPa absolute, a liquid hourly space velocity of from about 0.2 to 10 hr−1 and a ratio of free hydrogen to feedstock hydrocarbons of about 0.5 to 10 to obtain a paraxylene-rich product containing paraxylene in excess of its equilibrium concentration at disproportionation conditions.
A process for the production of paraxylene comprising the steps of:
- (a) selectively precoking a zeolitic catalyst in a catalyst bed by contacting the catalyst with a coke-forming feed at precoking conditions comprising an inlet temperature of from about 300° to about 700° C., a pressure of from about 100 kPa to 4 MPa absolute, a liquid hourly space velocity of from about 0.2 to 10 hr−1, a molar ratio of free hydrogen to feedstock hydrocarbons of about 0.2 to 5 and a temperature differential across the bed of the catalyst of between a 3° C. increase and a 4° C. decrease to deposit between about 5 and 40 mass-% carbon on the catalyst and obtain a selectively precoked catalyst;
- and,
- (b) disproportionating an aromatics-rich feedstock comprising contacting the feedstock with the selectively precoked catalyst bed in a disproportionation zone at disproportionation conditions comprising an inlet temperature of from about 200° to about 600° C., a pressure of from about 100 kPa to 6 MPa absolute, a liquid hourly space velocity of from about 0.2 to 10 hr−1 and a ratio of free hydrogen to feedstock hydrocarbons of about 0.5 to 10 to obtain a paraxylene-rich product containing paraxylene in excess of its equilibrium concentration at disproportionation conditions;
- and,
- (c) recovering pure paraxylene from the paraxylene-rich product by one or both of adsorption and crystallization.
2 more elements
Dependencies are inferred from the claim text.