CATALYST AND METHOD FOR PRODUCING CHLORINE BY MEANS OF A GAS-PHASE OXIDATION
A catalyst material for producing chlorine by the catalytic gas-phase oxidation of hydrogen chloride, wherein the catalyst comprises oxide compounds of cerium as active component components and zirconium dioxide as supporting component and the catalyst h as a particularly high space-time yield with respect to the reactor volume
1 . A catalyst material comprised of porous catalyst support and catalytic coating for a process for thermocatalytic preparation of chlorine from hydrogen chloride and oxygen-containing gas, said catalyst material comprising: at least one oxide compound of cerium as a catalytically active component and at least zirconium dioxide as a support component, and having a lanthanum content in the form of La 2 O 3 based on the calcined catalyst of less than 5% by weight.
2 . The catalyst material as claimed in claim 1 , wherein the calcined catalyst has a bulk density of at least 1000 kg/m 3 , measured in a DN100 measuring cylinder with fill height 350 mm, and wherein the principal dimension of the particles of the catalyst material averages at least 0.5 mm.
3 . The catalyst material as claimed in claim 1 , wherein the catalyst support is comprised of zirconium dioxide to an extent of at least 50% by weight.
4 . The catalyst material as claimed in claim 1 , wherein the lanthanum content in the form of La 2 O 3 , based on the calcined catalyst, is less than 3% by weight.
5 . The catalyst material as claimed in claim 1 , wherein the porous catalyst support in the uncoated state has a bimodal pore radius distribution, where the median of a pore class 1 is from 30 to 200 nm and the median of a pore class 2 is from 2 to 25 nm, measured by means of mercury porosimetry.
6 . The catalyst material as claimed in claim 1 , wherein the catalyst support in the uncoated state has a surface area of 30 to 250 m 2 /g, measured by the method of nitrogen adsorption with BET evaluation.
7 . The catalyst material as claimed in claim 1 , wherein the zirconium dioxide support component is present in the monoclinic crystal form to an extent of at least 90% by weight.
8 . The catalyst material as claimed in claim 1 , wherien the cerium content is 1 to 20% by weight.
9 . The catalyst material as claimed in claim 1 , wherein the oxide compounds of cerium are the exclusive catalytic active components on the catalyst support.
10 . The catalyst material as claimed in claim 1 , wherein the oxide compounds of cerium are selected from the group consisting of Ce(III) oxide (Ce 2 O 3 ) and cerium(IV) oxide (CeO 2 ).
11 . The catalyst material as claimed in claim 1 , wherein the catalyst material is obtained by applying a cerium compound selected from the group consisting of cerium nitrate, acetate and chloride to the support in solution by means of dry impregnation, and then drying the impregnated support and calcining it.
12 . (canceled)
13 . A process for thermocatalytic preparation of chlorine from hydrogen chloride and oxygen-containing gas, wherein the catalyst used is a catalyst material as claimed in claim 1 .
14 . The process as claimed in claim 13 , wherein the gas phase oxidation is conducted isothermally in at least one reactor.
15 . The process as claimed in claim 13 , wherein the gas phase oxidation is conducted in an adiabatic reaction cascade comprising at least two series-connected adiabatic reaction stages with intermediate cooling.
16 . The process as claimed in claim 13 , wherein the cerium-containing catalyst material is combined with a catalyst comprising ruthenium or ruthenium compounds on a separate support, using the ruthenium catalyst as a low-temperature component, and the cerium-containing catalyst material as a high-temperature component.
17 . The process as claimed in claim 16 , wherein the two different catalyst types are arranged in different reaction zones.