310 results about "Oxygen storage capacity" patented technology

A co-catalyst for purifying an exhaust gas which can be used for a loner period of time as an actual catalyst by using the cerium oxide in the conventional co-catalyst for purifying the exhaust gas as a cerium-containing complex oxide for elevating the resistance to heat and suppressing the performance reduction due to thermal deterioration and by making a specific surface area and an oxygen storage capacity over specified values. A co-catalyst for purifying an exhaust gas of the present invention includes a composite oxide including (a) cerium; and (b) at least one element selected from the group consisting of zirconium, yttrium, strontium, barium and a rare-earth element supported on a particulate aluminum oxide support; a specific surface area of the co-catalyst after sintering being not less than 40 m2/g; an oxygen storage capacity at 400° C. being not less than 10 mumols/g and an oxygen storage capacity at 700° C. being not less than 100 mumols/g.

A system and method for controlling an internal combustion engine for low emissions include an inner feedback control loop to control the engine fuel/air ratio with feedback provided by a first exhaust gas sensor and an outer feedback control loop that modifies the fuel/air ratio reference provided to the inner feedback control loop based on feedback signals provided by the first exhaust gas sensor and a second exhaust gas sensor. The fuel/air ratio reference signal controller adapts to the oxygen storage capacity of the catalyst by modeling the catalyst as an integrator with an unknown gain and estimating the catalyst gain based on the first and second exhaust gas sensor signals. Using the estimated catalyst gain, an adaptive controller gain factor is determined and subsequently used to determine the fuel/air ratio reference signal provided to the fuel/air ratio controller of the inner feedback control loop.

An engine exhaust system includes a catalytic converter. An inlet sensor senses a first oxygen level of exhaust gases entering the catalytic converter. An outlet sensor senses a second oxygen level of exhaust gases exiting the catalytic converter. A controller communicates with a fuel system of an engine, the inlet sensor, and the outlet sensor. The controller initiates a rich condition after a fuel cut-off period and calculates a mass of oxygen released by the catalytic converter based on a mass air flow into the engine. The controller calculates a target oxygen storage capacity (OSC) of the catalytic converter over a target time period.

The object of the invention is to provide an exhaust gas purifying catalyst having a high oxygen storage capacity without changing the usage amount of the oxygen storage component. According to the present invention, the exhaust gas purifying catalyst containing (a) a ceria-zirconia composite oxide containing ceria in a higher amount than zirconia, (b) a ceria-zirconia composite oxide containing zirconia in a higher amount than ceria, and (c) a ceria-zirconia composite oxide having a pyrochlore-type regular array structure is provided. The exhaust gas purifying catalyst of the present invention has a higher oxygen storage capacity than conventional catalysts and is effective in reducing the amount of NOx emission.

Described is a method for the production of metal oxides, in particular mixed metal oxides such as ceria/zirconia, and metal oxides obtainable by said method. Due to high enthalpy solvents with a high carboxylic acid content said metal oxides have improved properties. For example ceria/zirconia has excellent oxygen storage capacity at high zirconium levels up to more than 80% of whole metal content.

A cerium-zirconium composite metal oxide having improved durability at high temperature and a stable oxygen storage capacity is provided. The cerium-zirconium composite metal oxide is characterized in that the total mole number of Ce and Zr is at least 85% based on the total mole number of metal in the composite metal oxide, a molar ratio Ce/Zr is within a range from 1/9 to 9/1, and an isoelectric point of the composite metal oxide is more than 3.5. Preferably, the molar ratio Ce/Zr is within a range from 3/7 to 7/3 and the isoelectric point is within a range from 3.8 to 5.0, and the cerium-zirconium composite metal oxide contains a rare earth metal (excluding Ce) in a concentration of less than 15% by mole based on the total mole number of metal in the composite metal oxide. Also the present invention provides a cerium-zirconium composite metal oxide, characterized in that CeO₂ forms a core surrounded by ZrO₂.

ZPGM-ZRE catalyst system substantially free from platinum group (PGM) and rare earth (RE) metals for TWC application is disclosed. Disclosed ZPGM-ZRE catalyst system may include pure alumina as washcoat and a Cu—Mn stoichiometric spinel with Nb₂O₅—ZrO₂ support oxide, as ZPGM-ZRE catalyst in overcoat. Disclosed ZPGM-ZRE catalyst systems are found to have high thermal stability, catalyst activity, and high oxygen storage capacity compared to commercial PGM catalyst system that includes Ce-based oxygen storage material (OSM).

Various methods are provided for operating an emission control device. In one example, a method for an emission control device including a catalyst and a filter comprises passively regenerating the filter, and adjusting, via a controller, a duration of active regeneration of the filter based on an oxygen storage capacity of the emission control device.

An air-fuel ratio control system maintaining constant an oxygen storage amount or oxygen release amount per unit time with respect to an exhaust purification catalyst having an oxygen storage capacity even if the intake air amount changes is provided.

An air-fuel ratio control system of an internal combustion engine having an intake air amount detecting means, a linear air-fuel ratio sensor arranged at an upstream side of an exhaust purification catalyst, an O₂ sensor arranged at a downstream side of said exhaust purification catalyst, a target air-fuel ratio controlling means for performing feedback control of a target air-fuel ratio of exhaust flowing into the exhaust purification catalyst based on output information from the intake air amount detecting means and the O₂ sensor, and a fuel injection amount controlling means for performing feedback control of the fuel injection amount based on output information of the linear air-fuel ratio sensor so as to achieve the target air-fuel ratio, characterized in that the target air-fuel ratio controlling means performs feedback control of the target air-fuel ratio so that even when the intake air amount changes, a correction amount per unit time of an oxygen storage amount of the exhaust purification catalyst is made constant.

The invention relates to a solid liquid supported catalyst and in particular relates to high-performance cerium zirconium oxide. The high-performance cerium zirconium oxide is prepared from the following chemical ingredients in parts by weight: cerium oxide, zirconium oxide, aluminum oxide, praseodymium oxide, lanthanum oxide, neodymium oxide, yttrium oxide, samarium oxide, vanadium oxide, chromic oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, manganese oxide, nickel oxide and the like. The invention also provides a preparation method of the high-performance cerium zirconium oxide. The preparation method comprises the steps of mixing all raw materials, adding surface active agents, regulating pH value to be 8-10 to obtain gelatinous precipitates, and calcinating to obtain the cerium zirconium oxide. The solid liquid supported catalyst can overcome the doping defect caused by doping in the cerium zirconium carrier and can improve the thermal stability, the aged specific surface area and the oxygen storage capacity of the supported catalyst; and the preparation method is simple, the technological process is simple and the method facilitates large-scale industrial production.

A catalyst deterioration detecting system of an internal combustion engine includes a measuring unit that measures the oxygen storage capacity of a catalyst, a detector that detects or estimates the temperature of the catalyst, and a detector that detects poisoning of the catalyst based on the relationship between a change in the catalyst temperature and a change in the oxygen storage capacity corresponding to the change in the catalyst temperature. The change in the oxygen storage capacity corresponding to the change in the catalyst temperature varies depending on the presence or absence of poisoning of the catalyst. Thus, the catalyst deterioration detecting system is able to favorably detect poisoning of the catalyst by utilizing this relationship, and distinguish temporary deterioration due to catalyst poisoning from permanent deterioration. A method of detecting deterioration of the catalyst is also provided.

The invention discloses a method for preparing a cerium oxide-zirconium oxide based composite rare-earth oxide. The method comprises the following steps of: (1) heating a zirconium salt solution at room temperature, slowly adding sulfate ions, controlling the temperature rise rate so that the temperature is increased in the range of 90-95 DEG C when the sulfate ions are added completely, and then preserving heat for 20-100 minutes, thereby forming a zirconium basic sulfate composite salt precursor; (2) adding a cerium salt and a rare-earth metal salt to the precursor solution and stirring evenly, thereby obtaining a slurry; (3) settling the slurry by using basic carbonate and/or a basic oxalate solution, thereby obtaining a precipitate; and (4) filtering and washing the precipitate obtained in the step (3), removing purities, and calcining the washed precipitate. The cerium oxide-zirconium oxide based composite rare-earth oxide prepared by the method by controlling raw materials and process conditions has the characteristics of being high in total fine pore volume, high in fresh specific surface area, high in oxygen storage capacity and the like.

An exhaust gas purifying catalyst that contains a first oxygen storage material on which no noble metal is supported and which has a pyrochlore phase type regular array structure, and a second oxygen storage material which has a higher oxygen storage rate and a lower oxygen storage capacity than the first oxygen storage material and on which a platinum group noble metal is supported.

A catalyst diagnosis apparatus comprises a reaction rate calculation unit for calculating a reaction rate of chemical reaction in a three-way catalyst based on an output of an oxygen sensor, and an OSC indicator calculation unit for calculating an OSC indicator indicating an oxygen storage capacity (OSC) of the three-way catalyst based on outputs of a linear air-fuel ratio sensor and the oxygen sensor, and a catalyst degradation determination unit for determining degradation of the three-way catalyst based on the reaction rate and the OSC indicator. The determination of the catalyst degradation can be performed with high accuracy in a manner adapted for influences of external environments, etc.

A catalyst deterioration diagnosing apparatus is provided with means for performing stoichiometric feedback control on the air-fuel ratio based on at least output from an upstream air-fuel ratio sensor provided upstream of a catalyst, means for measuring the oxygen storage capacity of the catalyst, and means for correcting the measured value of the oxygen storage capacity based on at least the output behavior of a downstream air-fuel ratio sensor provided downstream of the catalyst during the stoichiometric feedback control. The measured value of the oxygen storage capacity is corrected using the output behavior of the downstream air-fuel ratio sensor during stoichiometric feedback control. The diagnostic is performed after eliminating the effects from sulfur by correcting the measured value to a value corresponding to when low sulfur fuel is used, which makes it possible to prevent an erroneous diagnosis from being made.

An oxygen storage capacity (OSC) monitoring system for a vehicle having a catalytic converter includes a control module that determines a measured OSC based on an inlet sensor signal (ISS) that is responsive to an oxygen content of exhaust flowing into the catalytic converter. The control module determines a normalization ratio based the measured OSC and determines a PASS/FAIL status of the catalytic converter based on the normalization ratio.