Process for preparing a platinum-rhenium catalyst on an alumina support

Claim 2

A PROCESS FOR PREPARING AN ALUMINA-SUPPORTED, RHENIUM AND PLATINUM SERIES METAL-CONTAINING CALCINED CATALYST WHICH COMPRISES THE FOLLOWING STEPS: I. DRYING AN AQUEOUS SLURRY OF HYDRATED ALUMINA TO OBTAIN A MIXTURE WHICH CAN BE FORMED INTO MACROSIZE PARTICLES; II. FORMING THE MIXTURE INTO MACROSIZE PARTICLES; III. CALCINING THE PARTICLES AT A TEMPERATURE FROM ABOUT 800 TO 1800*F SO AS TO PROVIDE THE PARTICLES WITH A SURFACE AREA OF BELOW ABOUT 350 SQUARE METERS PER GRAM, WITH THE PROVISO THAT SAID CALCINING IS CONDUCTED AT AT LEAST ABOUT 1200*F WHEN IT IS CONDUCTED IN THE SUBSTANTIAL ABSENCE OF WATER VAPOR; 1V. IMPREGNATING THE CLACINED PARTICLES WITH AQUEOUS SOLUTION OF WATER-SOLUBLE PLATINUM SERIES METAL ACID OR SALT AND AQUEOUS SOLUTION OF WATER-SOLUBLE RHENIUM ACID OR SALT IN AN AMOUNT SUFFICIENT TO PROVIDE ABOUT 0.1 TO 1 WEIGHT PERCENT OF SAID PLATINUM SERIES METAL AND ABOUT 0.1 TO 2 WEIGHT PERCENT OF SAID RHENIUM, CALCULATED AS THE FREE METALS, IN THE FINAL CATALYST; AND V. RECLACINING THE IMPREGNATED PARTICLES AT A TEMPERATURE FROM ABOUT 600 TO ABOUT 1200*F.

Claim 3

The process according to claim 1 wherein the calcining of step (iii) is conducted in the presence of air.

Claim 4

The process according to claim 1 wherein the calcining of step (iii) is conducted at a temperature of about 900 to 1300*F. and in the presence of air which contains sufficient water vapor to be saturated at about 70-80*F.

Claim 5

The process according to claim 3 wherein the platinum series metal is platinum.

Claim 6

The process according to claim 3 wherein the drying of step (i) is conducted at a temperature of up to about 400*F.

Claim 7

The process according to claim 3 wherein the rhenium compound employed in step (iv) is selected from the group consisting of perrhenic acid, ammonium perrhenate, and mixtures of the foregoing.

Claim 8

The process according to claim 3 wherein the platinum series metal compound employed in step (iv) is chloroplatinic acid.

Claim 9

The process according to claim 3 wherein the particles formed in step (ii) have a minimum dimension of at least about 0.03 inch and a maximum dimension of up to about 1 inch.

Claim 10

A process for preparing an alumina-supported, rhenium and platinum-containing, calcined catalyst which comprises the following steps: i. drying an aqueous slurry of hydrated alumina to obtain a mixture which can be extruded into macrosize particles, said slurry containing about 5 to 16 weight percent of alumina, calculated as Al2O3; ii. extruding the mixture into particles having a minimum dimension of at least about 0.03 inch and a maximum dimension of up to about 0.5 inch; iii. calcining the extrudate so as to provide the particles with a surface area of about 125 to 300 square meters per gram, said calcining being accomplished by drying the extrudate at a temperature up to about 400*F. to lower the uncombined water content to less than about 5 percent, based on the weight of the extrudate, and then heating the dried extrudate to a temperature of about 900 to 1300*F. in the presence of air which contains sufficient water vapor to be saturated at about 70-80*F. iv. impregnating the calcined extrudate with aqueous solution of chloroplatinic acid and aqueous solution of a rhenium compound selected from the group consisting of ammonium perrhenate, perrhenic acid, and mixtures of the foregoing in an amount sufficient to provide about 0.1 to 1 weight percent of said platinum and about 0.1 to 2 weight percent of said rhenium, calculated as the free metals, in the final catalyst; and v. recalcining the impregnated extrudate, said recalcining being accomplished by drying the impregnated extrudate at a temperature of up to about 400*F. to lower the uncombined water content to less than about 5 percent, based on the weight of the extrudate, and then heating the dried extrudate in dry air to a temperature from about 850 to about 1000*F.

Claim 11

A process for preparing an alumina-supported, rhenium and platinum-containing, calcined catalyst which comprises the following steps: i. drying an aqueous slurry of hydrated alumina to obtain a mixture which can be extruded into macrosize particles, said slurry containing about 5 to 16 weight percent of alumina, calculated as Al2O3; ii. extruding the mixture into particles having a minimum dimension of at least about 0.03 inch and a maximum dimension of up to about 0.5 inch; iii. calcining the extrudate so as to provide the particles with a surface area of about 125 to 300 square meters per gram, said calcining being accomplished by drying the extrudate at a temperature up to about 400*F. to lower the uncombined water content to less than about 5 percent, based on the weight of the extrudate, and then heating the dried extrudate to a temperature of about 900 to 1300*F. in the presence of air which contains sufficient water vapor to be saturated at about 70-80*F. iv. impregnating the calcined extrudate with aqueous solution of chloroplatinic acid and aqueous solution of a rhenium compound selected from the group consisting of ammonium perrhenate, perrhenic acid, and mixtures of the foregoing in an amount sufficient to provide about 0.1 to 1 weight percent of said platinum and about 0.1 to 2 weight percent of said rhenium, calculated as the free metals, in the final catalyst; and v. recalcining the impregnated extrudate, said recalcining being accomplished by drying the impregnated extrudate at a temperature of up to about 400*F. to lower the uncombined water content to less than about 5 percent, based on the weight of the extrudate, and then heating the dried extrudate in dry air to a temperature from about 850 to about 1000*F.