Preparation of Ceria-zirconia Mixed Oxides with Improved Thermal Stability for Three-way Catalysts by a Modified Co-precipitation Method

doi:10.15541/jim20160288

Abstract

Abstract:

A series of ceria-zirconia mixed oxides (CZ-x; x=0, 20, 40 and 80) with Ce/Zr molar ratio of 3/2 were synthesized by co-precipitation method. In order to improve the thermal stability of ceria-zirconia mixed oxides, we extended the time for the primary grain to grow up by a modified synthesis reactor. The resulting samples were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, and transmission electron microscopy (TEM). The results revealed that bigger grain could be obtained by extending time for the primary grain to grow up, which was propitious to enhance the textural properties and structural properties of the materials. Thus, the thermal stability of the materials was improved. In this study, the materials were applied in the field of Pd-only three way catalysts (TWCs). The catalysts exhibited excellent catalytic performance and thermostability, showing better prospect in application.

Key words: ceria-zirconia composites, primary grain, co-precipitation, thermostability

CLC Number:

TQ174

WU Qing-Feng, CUI Ya-Juan, ZHANG Hai-Long, ZHOU Yi, LAN Li, WANG Jian-Li, CHEN Yao-Qiang. Preparation of Ceria-zirconia Mixed Oxides with Improved Thermal Stability for Three-way Catalysts by a Modified Co-precipitation Method[J]. Journal of Inorganic Materials, 2017, 32(3): 331-336.

Figures/Tables 12

References 19

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Samples	Phase composition	Lattice parameter/nm	Crystallite size/nm
CZ-0-d	Cubic	0.5421	3.7
CZ-20-d	Cubic	0.5422	3.8
CZ-40-d	Cubic	0.5380	4.0
CZ-80-d	Cubic	0.5380	4.3
CZ-0-f	Cubic	0.5274	4.8
CZ-20-f	Cubic	0.5284	4.8
CZ-40-f	Cubic	0.5271	5.0
CZ-80-f	Cubic	0.5291	4.9
CZ-0-a	Cubic + tetragonal	0.5258^a	21.2
CZ-20-a	Cubic + tetragonal	0.5261^a	19.3
CZ-40-a	Cubic + tetragonal	0.5286^a	17.2
CZ-80-a	Cubic	0.5292	14.5

Samples	Phase composition	Lattice parameter/nm	Crystallite size/nm
CZ-0-d	Cubic	0.5421	3.7
CZ-20-d	Cubic	0.5422	3.8
CZ-40-d	Cubic	0.5380	4.0
CZ-80-d	Cubic	0.5380	4.3
CZ-0-f	Cubic	0.5274	4.8
CZ-20-f	Cubic	0.5284	4.8
CZ-40-f	Cubic	0.5271	5.0
CZ-80-f	Cubic	0.5291	4.9
CZ-0-a	Cubic + tetragonal	0.5258^a	21.2
CZ-20-a	Cubic + tetragonal	0.5261^a	19.3
CZ-40-a	Cubic + tetragonal	0.5286^a	17.2
CZ-80-a	Cubic	0.5292	14.5

Samples	Specific surface/(m²·g^-1)	Pore volume/(cm³·g^-1)	Average pore radius/nm
CZ-0-f	118	0.25	4.2
CZ-20-f	137	0.27	3.9
CZ-40-f	120	0.27	4.5
CZ-80-f	129	0.30	4.6
CZ-0-a	16	0.08	10.7
CZ-20-a	15	0.07	9.3
CZ-40-a	22	0.11	10.2
CZ-80-a	29	0.13	9.0

Samples	Specific surface/(m²·g^-1)	Pore volume/(cm³·g^-1)	Average pore radius/nm
CZ-0-f	118	0.25	4.2
CZ-20-f	137	0.27	3.9
CZ-40-f	120	0.27	4.5
CZ-80-f	129	0.30	4.6
CZ-0-a	16	0.08	10.7
CZ-20-a	15	0.07	9.3
CZ-40-a	22	0.11	10.2
CZ-80-a	29	0.13	9.0

Samples	Below 3 nm	Between 3 nm and 6 nm	Above 6 nm
CZ-0-f	37.6%	32.7%	29.7%
CZ-20-f	39.0%	31.1%	29.9%
CZ-40-f	30.1%	40.6%	29.3%
CZ-80-f	22.8%	47.8%	29.4%