CORE-SHELL STRUCTURE, METHOD OF MAKING SAID STRUCTURE AND CATALYST FOR CLEANING EXHAUST GASES, HAVING CORE-SHELL STRUCTURE

摘要

FIELD: chemistry.;SUBSTANCE: present invention relates to a core-shell structure, a method of making said structure and a catalyst for cleaning exhaust gases having a core-shell structure. Described is a core-shell structure for use as a catalyst support, characterised by availability of a central section primarily formed from a first metal oxide, and a shell section primarily formed from a second metal oxide different from the first metal oxide, where molar ratio of cerium to zirconium is in the range 0.2Ce/Zr2.0, and thickness of the shell section is greater than 20 nm. Described is a method of making a core-shell structure, comprising steps on which (a) an organic solvent containing a surfactant is mixed with an aqueous solution containing a precursor of the first metal oxide, to form inverted micelle containing an aqueous solution which contains the precursor of the first metal oxide, (b) the main aqueous solution is added to the inside of the inverted micelle to form the hydroxide of the precursor of the first metal oxide, (c) treating the obtained hydroxide with an aqueous solution containing a compound with at least two carboxyl groups in order to bond said hydroxide with at least one carboxyl group, (d) adding the aqueous solution containing a precursor of the second metal oxide different from the precursor of the first metal oxide to the treated hydroxide in order to bond the precursor of the second metal oxide with at least one of the remaining carboxyl groups of said compound with at least two carboxyl groups, (e) the main aqueous solution is added to the reverse micelle at step (d) to form a precipitate, and (f) said precipitate is dried and annealed, wherein molar ratio of metal elements M1 and M2 (M2/M1), which form the precursor of the first metal oxide and the precursor of the second metal oxide, is greater than 0.2 and less than 2.0; the first metal oxide is selected from a group comprising zirconium oxide, aluminium oxide, silicon oxide, titanium oxide and combinations thereof, and the second metal oxide is selected from a group comprising rare-earth oxides or combinations of two or more rare-earth oxides. Described also is a catalyst for cleaning exhaust gases having the core-shell structure described above or a core-shell structure, made using said method, as a catalyst support.;EFFECT: obtaining a core-shell structure, having controlled thickness of the shell section and higher thermal stability.;4 cl, 6 ex, 3 ex, 3 dwg