Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)

Yuan Jing, Zhengxu Cai, Chong Liu, Takashi Toyao, Zen Maeno, Hiroyuki Asakura, Satoru Hiwasa, Shuhei Nagaoka, Hiroshi Kondoh, Ken Ichi Shimizu

Research output: Contribution to journalArticle

Abstract

La-loaded Al2O3 (La/Al2O3) is a practical support for three-way catalysis (TWC) reactions. Although it has been reported that the addition of La to Al2O3 results in improved thermal stability to retain high specific surface areas, its effect on the catalytic reduction of NOx (DeNOx) has not been studied systematically. Herein, we describe the role of La in La/Al2O3-supported Pd catalysts (Pd/La/Al2O3) for TWC reactions. For that purpose, we employed various in situ spectroscopic studies, including infrared (IR), X-ray absorption fine structure (XAFS), and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in combination with density functional theory (DFT) calculations. The obtained results revealed that Pd0 species supported on La/Al2O3 are more electron-deficient compared to those on pristine Al2O3 without La(Pd/Al2O3). Kinetic studies using powdered catalysts revealed that the addition of La suppresses the poisoning effect by CO during the DeNOx reactions. In addition to the catalytic tests with powdered catalysts, monolithic honeycomb forms of the catalysts were prepared and employed for TWC reactions, which showed that Pd/La/Al2O3 exhibits higher DeNOx activity than Pd/Al2O3. In this study, we also reexamined the effective loading amount of La, which has traditionally been ∼3-5 wt % of La for TWC processes in order to retain the high specific surface area of the La/Al2O3 supports. Our investigations showed that an increased La loading (15 wt %) is even more effective for the DeNOx reactions tested in this study due to the higher reactivity toward NO and the greater suppression of the poisoning effect of CO. The developed catalyst Pd/La(15)/Al2O3 has also been tested in a commercial vehicle and has been evaluated on a practical driving mode test cycle (LA-4; city cycle of U.S. Federal and California), where it showed a better catalytic performance than the conventionally used Pd/La(3-5)/Al2O3 catalysts. Our study suggests that the loading amount of La in Pd/La/Al2O3 catalysts needs to be adjusted depending on the application systems, considering not only the support stability (surface areas) but also the promotional effect in the TWC process.

Original languageEnglish
Pages (from-to)1010-1023
Number of pages14
JournalACS Catalysis
DOIs
Publication statusAccepted/In press - 2020 Jan 1

Fingerprint

Catalyst supports
Catalysis
Catalysts
Carbon Monoxide
Specific surface area
Catalyst poisoning
Commercial vehicles
X ray absorption
Density functional theory
Thermodynamic stability
X ray photoelectron spectroscopy
Infrared radiation
Kinetics
Electrons

Keywords

  • electron-deficient Pd
  • in situ XAFS
  • NAP-XPS
  • Pd/La/AlO
  • three-way catalysis (TWC)

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this

Jing, Y., Cai, Z., Liu, C., Toyao, T., Maeno, Z., Asakura, H., ... Shimizu, K. I. (Accepted/In press). Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3). ACS Catalysis, 1010-1023. https://doi.org/10.1021/acscatal.9b03766

Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3). / Jing, Yuan; Cai, Zhengxu; Liu, Chong; Toyao, Takashi; Maeno, Zen; Asakura, Hiroyuki; Hiwasa, Satoru; Nagaoka, Shuhei; Kondoh, Hiroshi; Shimizu, Ken Ichi.

In: ACS Catalysis, 01.01.2020, p. 1010-1023.

Research output: Contribution to journalArticle

Jing, Y, Cai, Z, Liu, C, Toyao, T, Maeno, Z, Asakura, H, Hiwasa, S, Nagaoka, S, Kondoh, H & Shimizu, KI 2020, 'Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)', ACS Catalysis, pp. 1010-1023. https://doi.org/10.1021/acscatal.9b03766
Jing, Yuan ; Cai, Zhengxu ; Liu, Chong ; Toyao, Takashi ; Maeno, Zen ; Asakura, Hiroyuki ; Hiwasa, Satoru ; Nagaoka, Shuhei ; Kondoh, Hiroshi ; Shimizu, Ken Ichi. / Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3). In: ACS Catalysis. 2020 ; pp. 1010-1023.
@article{cd5d08d181b74aee9d37372cf732e9b8,
title = "Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)",
abstract = "La-loaded Al2O3 (La/Al2O3) is a practical support for three-way catalysis (TWC) reactions. Although it has been reported that the addition of La to Al2O3 results in improved thermal stability to retain high specific surface areas, its effect on the catalytic reduction of NOx (DeNOx) has not been studied systematically. Herein, we describe the role of La in La/Al2O3-supported Pd catalysts (Pd/La/Al2O3) for TWC reactions. For that purpose, we employed various in situ spectroscopic studies, including infrared (IR), X-ray absorption fine structure (XAFS), and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in combination with density functional theory (DFT) calculations. The obtained results revealed that Pd0 species supported on La/Al2O3 are more electron-deficient compared to those on pristine Al2O3 without La(Pd/Al2O3). Kinetic studies using powdered catalysts revealed that the addition of La suppresses the poisoning effect by CO during the DeNOx reactions. In addition to the catalytic tests with powdered catalysts, monolithic honeycomb forms of the catalysts were prepared and employed for TWC reactions, which showed that Pd/La/Al2O3 exhibits higher DeNOx activity than Pd/Al2O3. In this study, we also reexamined the effective loading amount of La, which has traditionally been ∼3-5 wt {\%} of La for TWC processes in order to retain the high specific surface area of the La/Al2O3 supports. Our investigations showed that an increased La loading (15 wt {\%}) is even more effective for the DeNOx reactions tested in this study due to the higher reactivity toward NO and the greater suppression of the poisoning effect of CO. The developed catalyst Pd/La(15)/Al2O3 has also been tested in a commercial vehicle and has been evaluated on a practical driving mode test cycle (LA-4; city cycle of U.S. Federal and California), where it showed a better catalytic performance than the conventionally used Pd/La(3-5)/Al2O3 catalysts. Our study suggests that the loading amount of La in Pd/La/Al2O3 catalysts needs to be adjusted depending on the application systems, considering not only the support stability (surface areas) but also the promotional effect in the TWC process.",
keywords = "electron-deficient Pd, in situ XAFS, NAP-XPS, Pd/La/AlO, three-way catalysis (TWC)",
author = "Yuan Jing and Zhengxu Cai and Chong Liu and Takashi Toyao and Zen Maeno and Hiroyuki Asakura and Satoru Hiwasa and Shuhei Nagaoka and Hiroshi Kondoh and Shimizu, {Ken Ichi}",
year = "2020",
month = "1",
day = "1",
doi = "10.1021/acscatal.9b03766",
language = "English",
pages = "1010--1023",
journal = "ACS Catalysis",
issn = "2155-5435",
publisher = "American Chemical Society",

}

TY - JOUR

T1 - Promotional Effect of la in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)

AU - Jing, Yuan

AU - Cai, Zhengxu

AU - Liu, Chong

AU - Toyao, Takashi

AU - Maeno, Zen

AU - Asakura, Hiroyuki

AU - Hiwasa, Satoru

AU - Nagaoka, Shuhei

AU - Kondoh, Hiroshi

AU - Shimizu, Ken Ichi

PY - 2020/1/1

Y1 - 2020/1/1

N2 - La-loaded Al2O3 (La/Al2O3) is a practical support for three-way catalysis (TWC) reactions. Although it has been reported that the addition of La to Al2O3 results in improved thermal stability to retain high specific surface areas, its effect on the catalytic reduction of NOx (DeNOx) has not been studied systematically. Herein, we describe the role of La in La/Al2O3-supported Pd catalysts (Pd/La/Al2O3) for TWC reactions. For that purpose, we employed various in situ spectroscopic studies, including infrared (IR), X-ray absorption fine structure (XAFS), and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in combination with density functional theory (DFT) calculations. The obtained results revealed that Pd0 species supported on La/Al2O3 are more electron-deficient compared to those on pristine Al2O3 without La(Pd/Al2O3). Kinetic studies using powdered catalysts revealed that the addition of La suppresses the poisoning effect by CO during the DeNOx reactions. In addition to the catalytic tests with powdered catalysts, monolithic honeycomb forms of the catalysts were prepared and employed for TWC reactions, which showed that Pd/La/Al2O3 exhibits higher DeNOx activity than Pd/Al2O3. In this study, we also reexamined the effective loading amount of La, which has traditionally been ∼3-5 wt % of La for TWC processes in order to retain the high specific surface area of the La/Al2O3 supports. Our investigations showed that an increased La loading (15 wt %) is even more effective for the DeNOx reactions tested in this study due to the higher reactivity toward NO and the greater suppression of the poisoning effect of CO. The developed catalyst Pd/La(15)/Al2O3 has also been tested in a commercial vehicle and has been evaluated on a practical driving mode test cycle (LA-4; city cycle of U.S. Federal and California), where it showed a better catalytic performance than the conventionally used Pd/La(3-5)/Al2O3 catalysts. Our study suggests that the loading amount of La in Pd/La/Al2O3 catalysts needs to be adjusted depending on the application systems, considering not only the support stability (surface areas) but also the promotional effect in the TWC process.

AB - La-loaded Al2O3 (La/Al2O3) is a practical support for three-way catalysis (TWC) reactions. Although it has been reported that the addition of La to Al2O3 results in improved thermal stability to retain high specific surface areas, its effect on the catalytic reduction of NOx (DeNOx) has not been studied systematically. Herein, we describe the role of La in La/Al2O3-supported Pd catalysts (Pd/La/Al2O3) for TWC reactions. For that purpose, we employed various in situ spectroscopic studies, including infrared (IR), X-ray absorption fine structure (XAFS), and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in combination with density functional theory (DFT) calculations. The obtained results revealed that Pd0 species supported on La/Al2O3 are more electron-deficient compared to those on pristine Al2O3 without La(Pd/Al2O3). Kinetic studies using powdered catalysts revealed that the addition of La suppresses the poisoning effect by CO during the DeNOx reactions. In addition to the catalytic tests with powdered catalysts, monolithic honeycomb forms of the catalysts were prepared and employed for TWC reactions, which showed that Pd/La/Al2O3 exhibits higher DeNOx activity than Pd/Al2O3. In this study, we also reexamined the effective loading amount of La, which has traditionally been ∼3-5 wt % of La for TWC processes in order to retain the high specific surface area of the La/Al2O3 supports. Our investigations showed that an increased La loading (15 wt %) is even more effective for the DeNOx reactions tested in this study due to the higher reactivity toward NO and the greater suppression of the poisoning effect of CO. The developed catalyst Pd/La(15)/Al2O3 has also been tested in a commercial vehicle and has been evaluated on a practical driving mode test cycle (LA-4; city cycle of U.S. Federal and California), where it showed a better catalytic performance than the conventionally used Pd/La(3-5)/Al2O3 catalysts. Our study suggests that the loading amount of La in Pd/La/Al2O3 catalysts needs to be adjusted depending on the application systems, considering not only the support stability (surface areas) but also the promotional effect in the TWC process.

KW - electron-deficient Pd

KW - in situ XAFS

KW - NAP-XPS

KW - Pd/La/AlO

KW - three-way catalysis (TWC)

UR - http://www.scopus.com/inward/record.url?scp=85077649167&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85077649167&partnerID=8YFLogxK

U2 - 10.1021/acscatal.9b03766

DO - 10.1021/acscatal.9b03766

M3 - Article

AN - SCOPUS:85077649167

SP - 1010

EP - 1023

JO - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

ER -