URANIUM CATALYST ON A SUBSTRATE HAVING A SPECIFIC PORE SIZE DISTRIBUTION, METHOD FOR THE PRODUCTION THEREOF AND USE THEREOF
The present invention relates to a novel uranium catalyst on a support of particular pore size distribution, to a process for preparation thereof, and to the use thereof in the course of processes for preparing chlorine from hydrogen chloride.
1 . Catalyst for heterogeneously catalytic oxidation of hydrogen chloride to chlorine, comprising at least one catalytically active component composed of a uranium compound and a support material composed of aluminium oxide, wherein the catalyst has a bimodal pore size distribution.
2 . Catalyst according to claim 1 , wherein the uranium compound is a uranium oxide with a stoichiometric composition of UO 2.1 to UO 2.9 .
3 . Catalyst according to claim 1 , wherein the uranium compound is a uranate of at least one alkali metal and/or alkaline earth metal.
4 . Catalyst according to claim 1 , wherein the bimodal pore size distribution has a first range of smaller pore diameter from 1 to 20 nm and a second range of greater pore diameter from 100 to 5000 nm.
5 . Catalyst according to claim 1 , wherein the bimodal pore size distribution has a proportion of pore volumes in the range of the smaller pore diameter of 40% to 60% and a proportion of pore volumes in the range of the greater pore diameter of 60% to 40%, the sum of the proportions being less than or equal to 100%.
6 . Catalyst according to claim 1 , wherein the proportion of the uranium compound in the overall catalyst is in the range from 1 to 40% by weight.
7 . Process for preparing a catalyst for the heterogeneously catalytic oxidation of hydrogen chloride to chlorine, comprising at least the steps of:
a) providing a solution A comprising a uranium salt in a solvent,
b) coating particles of aluminium oxide with solution A to obtain coated particles B,
c) drying the coated particles B, and
d) optionally shaping shaped bodies from the coated particles B obtained from one of steps b) and c).
8 . Process according to claim 7 , wherein the uranium salt is selected from the group consisting of uranyl acetate UO 2 Ac 2 , uranyl acetate dihydrate UO 2 Ac 2 .2H 2 O, uranyl oxide nitrate UO 2 (NO 3 ) 2 , and uranyl oxide nitrate hexahydrate UO 2 (NO 3 ) 2 .6H 2 O.
9 . Process according to claim 8 wherein shaping according to step d) is performed, in which the particles B from step c) are shaped to shaped bodies by adding a binder and by subsequent drying, in the course of which drying step the particles B are pressed into a negative mould of the desired shaped body.
10 . Process according claim 7 , wherein the coated particles B from step b) are sent to drying under elevated pressure relative to atmospheric pressure, this pressure being obtained by compressing a negative mould of the desired shaped body around the particles B with which the negative mould has been filled.
11 . Process according to claim 7 , wherein the drying is performed at temperatures of 500° C. to 1500° C.
12 . Process according to claim 7 , wherein the drying is performed in a plurality of stages, a first stage involving preliminary drying at room temperature to 250° C. and a second stage further drying at temperatures of 500° C. to 1500° C.
13 . Process for preparing chlorine, wherein hydrogen chloride is oxidized with oxygen to chlorine in a reaction zone in the presence of a catalyst with bimodal pore size distribution comprising at least one catalytically active component composed of a uranium compound and a support material composed of aluminium oxide.
14 . Method of using a catalyst according to claim 1 as a catalyst for oxidizing hydrogen chloride to chlorine.