Patent ID: 6534431
Filing Date: 2003-03-18
Classification: B01J

Abstract:
A process for preparing a heterogeneous catalyst having at least one catalytically active species bound to the surface of a support material, said process comprising the steps of:(A) selecting the amount of catalytically active-species to be present in the heterogeneous catalyst; (B) pretreating a surface of a support material to provide a number of binding sites corresponding to the amount of catalytically active species to be present in the heterogeneous catalyst, as recited in step (A), wherein said pretreating comprises heat treatment, comprising increasing the temperature of the support to at least the same temperature as used to bind the catalytically active component, or chemical treatment, comprising treatment with steam or a dehydrating agent to add or remove hydroxyl groups, or both; (C) vaporizing a reagent containing a precursor of a catalytically active species to form a vapor; (D) introducing the vapor into a reaction chamber where the support material is kept at a higher temperature than the condensation temperature of the vaporized reagent, and contacting the vaporized reagent with the support material, whereby at least a portion,of the precursor of the catalytically active species in the vaporized reagent binds to the support material, wherein the pretreatment of the support occurs in the reaction chamber, wherein the vapor pressure of the vaporized reagent in the reaction chamber is sufficiently high and the duration of contacting between the vaporized reagent and the support material is sufficiently long that the reaction chamber contains an amount of precursor of catalytically active species that is at least equal to the number of available binding sites on the support material, wherein the temperature of the support material is sufficiently high that chemisorption of the precursor of the catalytically active species occurs, wherein the duration of contacting between the support material and the vaporized reagent is sufficiently long that all of the surface binding sites of the support material have been occupied by the precursor of the catalytically active species, whereby the surface binding sites of the support material are saturated at the prevailing temperature, and wherein said pretreated support is not removed from the reactor or exposed to ambient air between pretreatment and introduction of said vapor; (E) removing vaporized reagent containing any precursor of catalytically active species not bound to the support; and (F) posttreating the precursor of the catalytically active species bound to the support to convert it into catalytically active form.