Complex Sol - Gel Prepared By The Nzp Family Of Phosphate Materials

The powder CaZr₄(PO₄)₆ (simplified as CZP) belonging to NZP family was synthesized by Chelate Sol-Gel route and the effects of calcining temperature and solute acidity to powder phase and size distribution was studied in this paper. The best chelate dosage and ratio was searched by orthogonal experiments. CZP and KZP powder was synthesized under the best experimental conditions, and the phase, size distribution, topography, surface area, pore structure data of the powder was characterized. Synthesis mechanism of the powder was preliminarily studied. On the basis of the former research, the "CZP coating-cordierite honeycombed ceramics" composite carrier was prepared by Chelate Sol-Gel route and each parameters of the composite carrier were characterized by XRD, SEM, EDAX, BET etc. After the modification by lanthanide dioxide CeO₂, the monolithic three-way catalyst named "0.6%Pd/10% CeO₂-CZP- cordierite" was prepared by loading activity component. And the catalytic activity for auto engine exhaust treatment of the monolithic three-way catalyst was test on auto exhaust after-treatment tester. The results indicate that:(1) Single-phase Ca₂Zr₄(PO₄)₆ powder can be acquired by calcining the predecessor prepared by Chelate Sol-Gel method under 700℃. Degree of reuniting of the powder increases when calcining heat rises. Well crystallized single-phase CaZr₄(PO₄)₆ powder can be formed under neutral or alkaline circumstance.(2) Single-phase CaZr₄(PO₄)₆ powder can be synthesized under the best experimental conditions. The surface area of the powder is 34.29m²/g and the average particle size is about 2.3μm. The surface area of KZP powder is 27.55m²/g and the average particle size is about 2.1μm. But another phase was discovered in the KZP powder formed by Chelate Sol-Gel method.(3) The loading amount of CZP coating is linear to loading times. When loading percentage of CZP coating on cordierite honeycombed ceramics comes to 19.47%, the surface area of the composite carrier reaches 16.43 m²/g.(4) XRD pattern shows that the CaZr₄(PO₄)₆ coating assuredly form on the surface ofcomposite carrier. SEM and EDAX show that the coating joint well with cordierite honeycombed ceramics.(5) The "0.6%Pd/10% CeO₂-CZP- cordierite" monolithic Pd-only three-way catalyst was prepared on "CZP coating- cordierite honeycombed ceramics" composite carrier. The light-off temperature for CO, THC, NO_x is 384℃, 383℃, 397℃, and the operation windows of A/F ratio is 14.54 to 14.59.