| 摘要 |
A process that provides a catalytic rare earth oxide-coated microporous free-flowing bulk particulate wherein the amount of metal oxide coated thereon is high, without jeopardizing the effectiveness of the material. The rare earth metal oxide coated on the outer surface may be in the range of 20 to 70% by weight based on the total equivalent rare earth metal oxide and microporous particulate material content. In particular, a zeolite free-flowing bulk particulate having high loadings of rare earth metal oxide tends to be quite stable. For instance, when the rare earth metal oxide-coated zeolite free-flowing bulk particulate has been heat treated at temperatures less than about 200° C. and then slurried in water, typically, less than 30% by weight of the rare earth metal oxide (based on the total equivalent rare earth metal oxide content) is found to leach into water. This material has been found to have minimal leachability when heat treated above about 400° C. The process for making a catalytic rare earth metal oxide-coated microporous particulate material having greater than 20% by weight of said rare earth metal oxide coated on outer surfaces of said microporous particulate material, based on the total equivalent rare earth metal oxide and microporous particulate material content, the process comprises the steps of: i) combining an amount of a colloidal dispersion of rare earth metal oxide hydrate with a compatible microporous particulate material to form a slurry, the amount of the colloidal dispersion being sufficient to provide, when heat treated as per step (ii), greater than 20% by weight of the rare earth metal oxide, the microporous particulate material having an average pore size of less than 20 Å and the colloidal dispersion having a particle size of at least 20 Å, to position thereby, the colloidal dispersion on the outer surfaces of the microporous particulate material; and ii) heat treating the slurry at a temperature below about 200° C., above about 400° C., or sequential combinations thereof wherein the slurry is heat treated, firstly, at temperatures below about 200° C. and secondly, above about 400° C., to fix the resultant rare earth metal oxide on the outer surfaces of the microporous particulate material, to provide a free flowing bulk particulate.
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