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It is critical to develop high performance three-way catalysts to meet increasing regulations around the world. It was found that a double-layered catalyst loaded with Pt and Rh suppresses Pt-Rh alloying, thereby improving catalytic performance. A double-layered catalyst has the effect of decreasing OSC performance, but this has been overcome by a newly developed Rh support and suppressed Pt grain growth. The developed catalyst is capable of lowering the amount of PGM required by approximately 40%.

We have developed a revolutionary automotive catalyst that maintains high activity by the suppression of grain growth of precious metals. This catalyst contains Pd-perovskite crystal which has shown a capacity for self-regeneration of Pd in a cycle of solid solution and segregation in perovskite crystals [1, 2, 3, 4, 5 and 6]. We named this catalyst the “Intelligent Catalyst” and first commercialized it in the Japanese market in October 2002 [7, 8]. In this study, we investigated the activity of Pd at various temperatures to confirm that the self-regenerative mechanism worked well at low temperatures like those right after engine starting. We also examined the durability of perovskite structure at high temperatures and tested its catalytic activity after engine aging at high temperatures above 1000 °C up to 1100 °C. It is proved that the intelligent catalyst has both excellent activity and durability under practical conditions.

With emission regulations getting tighter and tighter, catalysts will need to be active at ever lower temperatures in order to meet future standards. To meet this need, automotive catalysts are being installed closer to the engine so as to be active immediately after start-up. In this location, catalysts must have high temperature durability. In this paper, we examined a heat-resistant support material, “hexa-aluminate”, for possible use in future automotive catalysts. Catalytic activity of hexa-aluminate was more better than La added γ - alumina after redox treatment in model gas and after engine aging. Since hexa-aluminate had the excellent thermal durability, and Pd, which are supported on it, maintains finer particles than those on La added γ-alumina. We suggest that hexa-aluminate is a effective support material for automotive catalysts. More specifically, hexa-aluminate is expected to be a key technology for meeting the stringent emission standards of the future.

We have reported the innovation of “An Intelligent Catalyst” which has the function for self-regeneration of Pd realized through the solid solution and segregation of Pd in a perovskite crystal [1, 2, 3, 4 and 5]. We have looked for a design configuration for LaFePdO3 perovskite in the washcoat by comparing single and double layer washcaots as well as different loading locations for precious metals in order to maximize the Intelligent Catalyst's function in the practical conditions. The catalysts were attached to an engine exhaust system and subjected to an accelerated aging. The bed temperature of the catalysts reached to 1050 °C. The performance of the catalysts was evaluated on the engine dynamometer. Catalytic activity and long durability were improved by development of the washcoat configuration. The optimum design of the washcoat was double-layer with a tri-metal (Pt, Rh and Pd) system. The perovskite was located in the lower layer.

In recent years the regulations governing emissions from automobiles have been strengthened as awareness of global environmental problems has increased. Furthermore, the amount of precious metals being used has continued to decrease due to concerns over the exhaustion of natural resources and worries about the risk of fluctuations in the price of these precious metals. As a result, a high performance three-way catalyst that can satisfy the emissions regulations is now required. By applying zone-coating and carrier degradation control technology, a high performance three-way catalyst has been developed. The zone-coating technology improves the conversion performance of the catalyst through improvement of HC and NOx conversion reactions and oxygen storage capacity (OSC) reactions. The addition of an Nd surface-enriched layer strengthened the mutual interactions between the carrier and Rh.

We have developed a Pd-intelligent catalyst with a self-regenerative function that is realized by the passage of Pd through consecutive solid solution and segregation states in and out of a perovskite crystal, and commercialized it for the first time in the world [1, 2, 3, 4, 5, 6, 7, 8 and 9]. In this study, we investigated the self-regenerative function of Rh as an alternative for Pd, in two types of Rh-perovskite (LaFeRhO3 and CaTiRhO3), and found that a CaTiRhO3 perovskite has an excellent capacity for the self-regenerative function of Rh. In a LaFeRhO3 perovskite with a composition similar to the Pd-perovskite (LaFePdO3), Rh was fixed so stably in the perovskite structure that it hardly segregated from the perovskite even in high temperature reduction atmospheres. However, in the CaTiRhO3 perovskite, with its A2+B4+O3 formula, the amount of Rh that actually segregated increased greatly in reduction atmospheres.

Growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. One of the key technologies is a new OSC material that has low surface area (SA) and high OSC performance. We enhanced the pyrochlore- ceria/zirconia (CZ) which has a very small SA. In order to enhance the heat resistance and promote the OSC reaction, we selected and optimized the additive element. This material showed high OSC performance especially in the temperature range of 400 degrees or less. Another key technology is washcoat structure that has high gas diffusivity by making connected pore in the washcoat (New pore forming technology).

Global focus on CO2 reduction and environmental protection is increasing. To comply with stricter exhaust gas regulations and reduce real world emissions, it is becoming increasingly important to improve the performance of three-way catalysts. Therefore, highly efficient conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) is required. In general, the more active the precious metals used, the better the conversion performance. However, precious metals have supply risks, such as price fluctuation and the uneven distribution of production areas. Therefore, it is necessary to lower emissions while also lowering the amount of precious metals used. This paper focuses on how catalysts are used and describes the development of a new three-way catalyst for the purpose of strengthening cold conversion and decreasing the usage of precious metals.

Further improvements in catalyst performance are required to help protect the atmospheric environment. However, from the viewpoint of resource availability, it is also necessary to decrease the amount of precious metals used at the active sites of the catalyst. Therefore, a high-performance three-way catalyst with an advanced coating layer has been developed to lower the amount of precious metal usage. Fuel efficiency improvement technologies such as high compression ratios and a large-volume exhaust gas recirculation (EGR) generally tend to increase the ratio of hydrocarbons (HC) to nitrogen oxides (NOx) in exhaust gas. This research focused on the palladium (Pd) loading depth in the coating layer with the aim of improving the hydrocarbon (HC) conversion activity of the catalyst.

A one-dimensional (1-D) micro-kinetic reaction model with considering mass transport inside porous washcoat was developed to promote an effective development of multi-functional catalysts. The validation of this model has been done successfully through the comparison with a set of basic experiments. A numerical simulation study was conducted for the various catalyst configurations of three-way catalysts under Federal Test Procedure (FTP75) condition. It was found that a double layer type had a significant advantage in the total mass emissions, especially in NOx emissions. The reaction mechanisms in these catalysts were numerically clarified from the view point of detailed reaction dynamics. We concluded that the utilization of the numerical simulation with the detailed chemistry was effective for the optimization of catalyst design.

In regard to small utility engines used in lawn and garden equipment and other commercial or industrial equipment, exhaust emission regulations have been implemented since 1995 in USA. In the State of California, USA, California Air Resources Board (CARB) Tier 2 emission regulations became effective from 2000. At this stage, the handheld engines are almost two-stroke engines, but this Tier 2 emission regulations are very stringent for HC emissions. In addition, the handheld engines are small, and so they do not have enough muffler volume to be equipped with larger catalysts. This paper describes the newly developed catalyst for two-stroke small engines, which is compact and excellent in HC conversion, to meet above requirements.