Denso Corporation

Nippondenso Co., Ltd.

Nippon Soken, Inc.

Masakazu Tanaka

Mamoru Mabuchi

Kazuhiko Koike

Hiroshi Mori

Tomohiko Nakanishi

Hiroyuki Usami

Kinji Hodaira

Tomomi Hase

Makoto Saito

Miho Ito

Tatsuo Sakai

Tosiharu Kondo

Takumi Suzawa

Takeshi Ueda

Takashi Kondo

Hiromi Sano

Keiji Ito

Takahiko Yamamoto

Jun Hasegawa

Mamoru Nishimura

Masakazu Murata

Yosiyasu Andou

Takashi Obata

Takahiro Kida

Yoshiyasu Andou

A ceramic support capable of supporting a catalyst comprising a ceramic body having fine pores with a diameter or width up to 1000 times the ion diameter of a catalyst component to be supported on the surface of the ceramic body, the number of the fine pores being not less than 1&#xd7;10pores per liter, is produced by introducing oxygen vacancies or lattice defects in the cordierite crystal lattice or by applying a thermal shock to form fine cracks.

Ceramic support capable of supporting a catalyst, a catalyst-ceramic body and processes for producing same

A ceramic body that can support a required amount of catalyst component, without lowering the characteristics such as strength, manufactured without forming a coating layer and providing a high performance ceramic catalyst body that is excellent in practical utility and durability. This ceramic body is made by substituting at least one of the constituent elements of cordierite that constitutes the substrate ceramic, for example Al, with W that is the element having an empty orbit in d or f orbit, has high bonding strength and is less susceptible to deterioration since the catalyst component Pt is supported by means of chemical bonding.

Ceramic body and ceramic catalyst body

This invention provides a method for producing a ceramic catalyst body that can directly support a catalyst on a ceramic support without disposing a coating layer on the ceramic support. In the invention, a catalyst solution containing a catalyst component consisting of a negative complex ion resulting from a catalyst precursor is prepared, and a pH of the catalyst solution is adjusted in such a manner as to satisfy the relation E&#x3e;Eand E&#x3e;0 where Eis a surface potential of a matrix phase consisting of a cordierite-W composite body relative to the pH of the catalyst solution and Eis a surface potential of a dispersed phase consisting of compounds other than the cordierite-W composite body. After the ceramic support is brought into contact with the catalyst solution to support the catalyst component, heat-treatment is conducted to bond the matrix phase consisting of the cordierite-W composite body and the catalyst component to support the catalyst on the ceramic support.

Production method of ceramic catalyst body

(i) In a ceramic catalyst body which comprises a ceramic carrier which has a multitude of pores capable of supporting a catalyst directly on the surface of a substrate ceramic and a catalyst supported on the ceramic carrier, a layer containing an anti-evaporation metal such as Rh is formed on the outer surface of catalyst metal particles such as Pt or Rh. The layer containing the anti-evaporation metal protects the catalyst metal and prevents evaporation thereof, thereby suppressing the deterioration; and/or (ii) A ceramic catalyst body is made by having a main catalyst component and a promoter component directly on a ceramic carrier which can directly support the catalyst by substituting a part of the constituent elements of cordierite, and a trap layer is provided in the upstream thereof for trapping sulfur which is a catalyst poisoning component included in the exhaust gas. Since sulfur included in the exhaust gas can be collected by the trap layer, the catalyst poisoning component can be removed from the gas which enters the catalyst, thus preventing catalyst poisoning.

Ceramic catalyst body

A catalyst-loaded ceramic filter made of a ceramic material capable of directly supporting a catalyst component thereon is capable of providing early activation of the catalyst with a low coefficient of thermal expansion and light weight, without compromising the high porosity of the filter substrate. A catalyst-loaded ceramic filter is made of a ceramic material of which one or more kinds of element among its constituent elements is substituted with an element other than the constituent elements, for example a ceramic material with a part of Si or other elements included in cordierite is substituted with W or Co, as a filter substrate of honeycomb structure having a number of cells separated by porous walls, and supporting a catalyst such as a noble metal directly on the W.

Ceramic filter and catalyst-loaded ceramic filter

This invention aims at achieving early activation by use of a catalytic body having a low thermal capacity, and a low pressure loss, without using a coating layer to reduce exhaust emission. The invention is directed also to improve exhaust purification performance by improving the combination of catalytic bodies and performance of each catalytic body. In the invention, a start catalystis arranged at an upstream portion of an exhaust pipe P of a car engine E and a three way catalystis disposed on the downstream side. The start catalystcan directly support catalytic components through chemical bonds by incorporating replacing elements into a substrate ceramic having high heat resistance such as cordierite. Because a coating layer is not necessary, the catalyst of the invention has a low heat capacity and a large open area and achieves reduction of exhaust emission, and reduction of a pressure loss, through early activation.

Catalyst for automobiles

A purification catalyst for exhaust gas is provided that uses a hexagonal cell monolithic carrier which is able to demonstrate purification performance that is superior to the case of using a square cell monolithic carrier. This purification catalyst for exhaust gas comprises a monolithic carrier ( ) provided with hexagonal cells ( ) of 200 cells/in or more in which the porosity of partition walls ( ) that form the cells ( ) is 25% or more; and, a catalyst layer ( ) arranged on the surface of the partition walls ( ) of the monolithic carrier ( ) that contains a catalyst component for purification of exhaust gas. The thickness of catalyst layer ( ) is 10-70 &mgr;m at its thin portion ( ), and its thick portion ( ) has a thickness of no more than 12 times that of thin portion ( ).

Purification catalyst for internal combustion engine exhaust gas

There is provided a honeycomb structural body with a lower-than-conventional heat capacity and excellent durability. A honeycomb structural body (,) having partition walls composed mainly of cordierite arranged in a honeycomb fashion is provided with fortified section (,) with a higher strength than the general section (,) at one end or both ends (,) in the direction of length of the partition walls (,). The fortified section (,) is given improved strength by having increased density with respect to the general section.

Honeycomb structural body and process for production of the same

Exhaust gas is caused to flow through a bypass passage during an adsorption mode. At this time, an adsorbing member adsorbs harmful components, e.g. HC, of the exhaust gas. Also, exhaust gas is caused to flow through the bypass passage to thermally desorb the harmful component held at the adsorbing member during a desorption mode. A quantity of heat given from exhaust gas to the adsorbing member during the desorption mode is calculated based on an operation state of an engine. It is determined that the desorption of the harmful components has been finished when the quantity of heat given to the adsorbing member reaches a total quantity of heat required for totally desorbing the harmful components adsorbed by the adsorbing member.

Engine exhaust gas purifying system

An exhaust gas purifying apparatus with a failure diagnosis function is provided. A failure diagnosis device determines that the apparats is failed when the temperature rising speed of an adsorbing device is equal to a set value or less during a gas adsorption process and if the temperature rising speed is equal to an upper limit or more or to a lower limit or less during a gas desorption process. Further, a failure diagnosis device similarly monitors the flow passing through the adsorbing device. A failure diagnosis device determines that the apparatus is failed if the concentration of discharge gas is equal to a set value or more in a discharge passage. And further, a failure diagnosis device measures the concentration of discharge gas flowing through a return passage to accumulate the amount of discharge gas in order to determine that the apparatus is failed if the accumulated value is equal to a set value or less. Exhaust gas sensors are installed in the return passage and the upstream side of the adsorbing device, respectively, and the period of time te from the activation of the return passage until the outputs from the exhaust gas sensors match or a correlation coefficient for these outputs is measured to diagnose failures in the apparatus.

Exhaust gas purifying apparatus

A change-over valve unit has a change-over valve for switching a bypass passage and an exhausting passage disposed in parallel therewith. An adsorbent is disposed in the bypass passage to adsorb exhaust components. An actuator of the change-over valve is isolated from an adsorption cylinder by a pedestal. Furthermore, rotary shafts of the control mechanism of the change-over valve are positioned within the bypass passage of the adsorber when the change-over valve is positioned to open the main exhaust passage. Thus, the heat of the exhaust gas flowing through the main exhaust passage is not transmitted to the rotary shafts.

Change-over valve unit for switching exhaust gas passages and exhaust

To be able to efficiently and rapidly reduce noxious exhaust gas components after starting of an engine without impeding activation of a catalyst device, and moreover to be able to perform rapid separation of noxious exhaust gas components, an adsorption device 5 for adsorbing noxious exhaust gas components is provided downstream of a catalyst device constituting a main mode of operation of exhaust-gas purification, a honeycomb body carrying adsorbent is disposed within the adsorption device, a bypass passage is formed to one side of the honeycomb body, and a switching valve is provided upstream of those components. After engine starting, the switching valve opens, exhaust gas flows in the passage on the honeycomb body side, and HC is adsorbed by the adsorbent. Meanwhile, when exhaust-gas temperature rises and a condition wherein HC separates from the adsorbent is reached, the switching valve is closed, adsorption components which have become high in temperature due to exhaust gas heat separate from an passage between the downstream of this switching valve and the honeycomb body, and are refluxed via reflux passages and to an upstream side of the foregoing catalyst device.

Exhaust emission purification apparatus

Two flow paths separated by a partition wall having a bore formed downstream of a catalyst unit provided in an exhaust pipe of an internal combustion engine. Adsorption means for adsorbing an HC component of an exhaust gas of the internal combustion engine is provided in one of the flow paths. When a temperature of the exhaust gas is above a predetermined level, the exhaust gas flows through the other flow path by means of a change-over valve. Because the bore is provided in the partition wall, the adsorption means is exposed to the exhaust gas and the HC component adsorbed by the adsorption means is easily desorbed because of the high temperature of the exhaust gas. A one-way valve which repeatedly performs an opening/closing operation due to pulsation of the exhaust gas, is provided between recirculation flow pipes. A position of the one-way valve between the recirculation flow pipes is determined so that a phase difference between the exhaust gas pulsation applied to the valve from the upstream side of the catalyst unit and the exhaust gas pulsation applied to the valve from the flow path of the adsorption means, inverts substantially by half-wavelength producing a large differential pressure applied to both the front and rear surfaces across the one-way valve, thereby rapidly recirculating the desorbed HC from the adsorption means to the catalyst unit. When the change-over valve is operated to a position shown by a dotted line to flow the exhaust gas through the adsorption means, the flow-in velocity of the exhaust gas flowing into the adsorption means is made uniform by the rectifying plate, thereby improving HC or the like adsorbing efficiency. When the change-over valve is turned to a position shown by a solid line for opening the exhaust gas flow path, so that the exhaust gas flows through the exhaust gas flow path, the rectifying plate prevents vortices from occurring on the upstream side of the adsorption means to thereby keep the once-adsorbed HC or the like from flowing out toward the exhaust gas pipe.

Exhaust gas purification apparatus

In an automotive engine exhaust pipe having a main flow passage and a bypass flow passage, the exhaust gas flows through the bypass flow passage having an heater-provided catalyst when an engine starts. After a main catalyst reaches a catalytic activation temperature, a switching valve switches the exhaust gas to flow through the main flow passage. The main shaft is divided into a driven shaft inserted into a bearing hole and a driving shaft inserted into another bearing hole, and therefore, a total length thereof in an axial direction is shorter than a length of the main shaft without having segments. Therefore, even though the driven shaft and the driving shaft are deformed into the arch shape, a deformation amount thereof is reduced so that inner peripheries of the bearing holes are not rubbed against the shafts. Since the driving shaft is smaller in diameter than the driven shaft, even though a cross section of the driving shaft is elliptically strained, the inner periphery of the bearing hole is not rubbed against the driving shaft. As a result, since a clearance between the driving shaft and the bearing hole can be narrowed, the exhaust gas from the clearance can be prevented from leaking.

Growing community of inventors

Okazaki, Japan

Masakazu Tanaka