Study on Screening Method for Catalysts Using Arc-Plasma Deposition (Part 2)
-Exploration of NH₃ Selective Oxidation Catalysts-

Teppei Ohori･Kasumi Yonemama (Isuzu Advanced Engineering Center)･Masato Machida (Kumamoto University)･Hisashi Ozawa (Isuzu Advanced Engineering Center)

Candidate materials for NH₃ selective oxidation (NH₃-SCO) catalysts were explored using a catalyst screening method based on arc plasma deposition. The obtained findings were applied to ammonia slip catalysts used in diesel engine aftertreatment systems, resulting in excellent catalytic performance characterized by high ammonia oxidation activity and low formation of NOx and N₂O byproducts.

Analysis of White Solids Derived from Urea Solution in a Urea SCR System

Kozue Sato･Hayato Kojima (Waseda University)･Junji Sakai (Isuzu Motors)･Jin Kusaka (Waseda University)

In urea SCR systems, deposits believed to originate from urea and its polymerization products form inside the exhaust pipe at low temperatures. In this study, deposits were collected at various low exhaust temperatures, and their compositions were estimated through thermochemical analysis. Furthermore, assuming that the decomposition process of the deposits upon heating consists of three-step first-order reactions, the collision frequency factors and activation energies for each reaction were experimentally determined.

A Study on Changes in NOx Conversion Performance of Urea SCR Catalysts Due to Urea Pulse Injection

Yujin Ueki･Fuka Yoshida･Jin Kusaka (Waseda University)

There is a growing need to reduce NOx emissions from diesel vehicles. In this study, the NOx conversion performance of a urea SCR catalyst was investigated by comparing steady urea injection at 1 Hz intervals with pulse injection, in which the presence or absence of urea injection was controlled at an arbitrary duty cycle. A computational model was developed to investigate the effect of urea injection methods on NOx conversion performance.

Hydrothermal aging mechanism on Cu-CHA type SCR catalysts assumed for use in H2-engines

Fumika Ono･Fuka Yoshida (Waseda University)･Takayuki Mori･Hiroya Yamada (Tokyo Roki)･Jin Kusaka (Waseda University)

With the global shift toward carbon neutrality, H2-engines are drawing substantial interest. For the aftertreatment of H2-engines, SCR systems are typically adopted for NOx purification. This study investigated the effects of hydrothermal aging and the water content in exhaust gas on multiple sorts of Cu-CHA type SCR catalysts through both experiments and numerical simulations.