Perovskite-Based Lean-Burn NO x Trap Catalysts Without Using Platinum Group Metals: K/LaCoO3/Ce1−x Zr x O2

Abstract

A series of Ce 1-x Zr x O 2 (x = 0, 0.1, 0.2, 0.3) solid solution supported lean-burn NO x trap (LNT) catalysts K/LaCoO 3 /Ce 1-x Zr x O 2 were prepared by successive impregnation. After sulfation the supported perovsikte LaCoO 3 was well maintained; reducing treatment partly destroyed the perovsikte, but it can be well recovered by re-oxidation treatment. Based on NO x storage and sulfurresisting performance of the catalysts, the optimal atomic ratio of Zr in Ce 1-x Zr x O 2 support is x = 0.2. The catalyst K/LaCoO 3 /Ce 0.8 Zr 0.2 O 2 exhibits much better NO x storage capacity than the Pt-based catalyst Pt/K/Ce 0.8 Zr 0.2 O 2 , which is highly related to its stronger capability for NO to NO 2 oxidation. During NO x storage much larger amounts of nitrate and nitrite species were identified by in situ DRIFTS over perovskite-based catalysts than over Pt-based one. The H 2 -TPR results reveal that after deep sulfation little sulfur species were deposited on the catalyst K/LaCoO 3 /Ce 1-x Zr x O 2 , showing strong sulfur-resisting ability. As a result, it is thought that the full replacement of Pt by perovskite LaCoO 3 in the corresponding LNT catalysts is feasible.

Global Kinetic Model of a Three-Way-Catalyst-Coated Gasoline Particulate Filter: Catalytic Effects of Soot Accumulation

“…The preparation of the CeZrO 2 /γ-Al 2 O 3 catalyst support was done by a citrate complexation incipient wetness impregnation method, − details of which can be found in our earlier publication . Thereafter, 0.92 wt % palladium was then added to the support CeZrO 2 /γ-Al 2 O 3 using the incipient wetness impregnation method.…”

Effects of Feed Gas Composition on Fresh and Aged TWC-Coated GPFs Loaded with Real Soot

“…The acid-to-metal-cation ratio was 2.1:1 to enable the total complexation of all metal ions. 21 The resulting solution was continuously stirred at 75 °C until obtaining a colorless gel and subsequently stirred overnight at room temperature. The concentrated solution was then impregnated on γ-Al 2 O 3 (Sasol, Puralox SBa200, Brunsbuẗtel, Germany) at a ratio of 20/80 wt % CeZr/Al 2 O 3 .…”

“…The support was prepared through a citrate complexation incipient wetness impregnation procedure. − This method consisted in dissolving Ce­(NO 3 ) 2 (Alfa Aesar, Haverhill, Massachusetts, United States) and Zr­(NO 3 ) 2 (Sigma-Aldrich, St. Louis, Missouri) precursors in a deionized water solution of citric acid (VWR International AB, Gothenburg, Sweden) at a ratio of 35/65 wt % Ce/Zr. The acid-to-metal-cation ratio was 2.1:1 to enable the total complexation of all metal ions . The resulting solution was continuously stirred at 75 °C until obtaining a colorless gel and subsequently stirred overnight at room temperature.…”

YCeZrO Ternary Oxide Solid Solution Supported Nonplatinic Lean-Burn NOx Trap Catalysts Using LaCoO3 Perovskite as Active Phase

“…Compared with the single oxide CeO 2 , the binary CeO 2 –ZrO 2 or ternary Y 2 O 3 –CeO 2 –ZrO 2 solid solution usually has larger specific surface area, more oxygen vacancies and higher oxygen storage capacity (OSC), − so, in this work, these solid solutions were prepared and used as supports of LNT catalysts. As to the NOx storage component, many works have demonstrated that potassium is an appropriate NOx storage material since it has strong basicity and better regeneration performance after sulfur poison as compared with barium. − …”

“…Such unconspicuous shifts suggest the formation of small amounts of CeZrO or YCeZrO solid solutions by referring to Ce x Zr 1-x O 2 system 28. In addition to the supports, the perovskite LaCoO 3…”