Integrated Performance Monitoring of Three‐Way Catalytic Converters by Self‐Regenerative and Adaptive High‐Temperature Catalyst and Sensors

Abstract

This study reports the performance of a self‐regenerating perovskite, LaFeCoPdO3 as a three‐way catalyst (TWC) and its use for self‐diagnostic by means of integrated Al‐doped TiO2 and LaFeCoPdO3 sensor arrays, consisted of semiconducting oxides as sensing layers and LaFeCoPdO3 as catalytic filter. Although perovskite catalyst yields a reasonable NO conversion performance at lower temperatures, it cannot fully compete with a commercial TWC under the TWC relevant temperatures and conditions. On the other hand, as‐coated duplex layer exhibits reasonable sensor property toward NO2 at 600 °C but sensor response deteriorates in NO2 + CO mixed gas environment. Ageing tests in the harsh exhaust peripherals however yield that perovskite improves the duplex layer's response through crack network and by protecting semiconducting oxide.

Recent progress of Rh‐based three‐way catalysts

“…Properly regulated supports in catalytic reactions will have a facilitating effect on catalytic reactions, for example, a large surface area is beneficial to improve the mass transfer efficiency, proper metal‐support interactions are helpful to enhance the stability of the metal‐active sites, electron transfer between the supports and active sites is favorable for the adsorption enhancement of gas molecules, and the unique oxygen storage capacity of the supports is friendly to the conduct of redox reactions. [ 23 , 24 ] In this section, we summarize several types of cerium‐based supports, aluminum‐based supports, metal foil supports, and other supports. Then, we discuss the advantages of each support in anticipation of finding the commonality of supports suitable for three‐way catalysts.…”

Perovskites as Geo-inspired Oxygen Storage Materials for Chemical Looping and Three-Way Catalysis: A Perspective

“…This allows the catalyst be highly responsive to the frequent P O 2 swings of the ICE exhaust . It was also suggested that the facile segregation and reincorporation of the Pd species can inhibit the sintering of metallic Pd particles. ,,, The reductive segregation of Pd 0 on the surface layer of the catalysts can occur at low temperatures (∼100 °C or higher). Meanwhile, oxidation of Pd 0 to Pd 2+ and its (partial) reincorporation into the perovskite framework occurs at ∼200 °C in an oxidative atmosphere .…”

“…For instance, the complexity for some of the doped perovskites makes the preparation of structured OSMs in commercial TWC systems challenging: wash-coated monolithic perovskite catalysts that usually contain complex components to obtain stable structure, perovskite oxides may react with the substrate, binder, or primer materials, resulting decreased catalytic activity and/or OSC. ,,, Other challenges include stability issues in the presence of sulfur for some perovskites. Self-regeneration of PGM can also be limited under certain practical exhaust conditions; over-reduction can lower NO reduction activity, and overoxidation of the materials can permanently lower activity for CO and HC oxidation reactions via the sintering of perovskite particles. The complexity of advanced perovskite system is also an issue.…”

“…Despite the above-mentioned challenges, recent research has revealed promising new directions that can potentially increase the competitiveness of perovskites for TWC applications. In addition, the adaptation of increasingly stringent emissions regulations, combined with increasingly complex internal combustion technologies, opens up new opportunities for perovskites research, as more active and stable TWC/OSM with higher OSC are pursued . Advanced ICE technologies such as gasoline direct ignition (GDI), gasoline compression ignition (GCI), and exhaust gas recirculation (EGR) all pose unique new challenges and opportunities for emissions control …”

“…194 the sintering of metallic Pd particles. 141,188,195,196 The reductive segregation of Pd 0 on the surface layer of the catalysts can occur at low temperatures (∼100 °C or higher). Meanwhile, oxidation of Pd 0 to Pd 2+ and its (partial) reincorporation into the perovskite framework occurs at ∼200 °C in an oxidative atmosphere.…”