摘要:
A catalyst for the removal of carbon monoxide, hydrocarbons and nitrogen oxides in an exhaust gas made by a process comprising:a) preparing a suspension comprising a liquid, a zeolite, a weak base, and salts of copper and silver,said zeolite being crystalline and having a Si/Al atomic ratio between about 5 and about 100, a pore size between about 0.5 nm and about 1.3 nm, essentially no octahedral aluminum detectable by .sup.27 Al NMR spectroscopy and a sodium ion exchange capacity, with regard to total aluminum content, greater than 75%, and wherein said suspension contains sufficient amounts of said copper and silver salts to result in a copper content in said catalyst, when finished, between about 0.5 wt. % and about 12 wt. % and a silver content between about 0.25 wt. % and about 20 wt. %;b) adding a sufficient amount of a strong base to raise the pH of the suspension to between about 7 and about 9, thereby creating a metal-containing zeolite support in said suspension;c) separating the support from said liquid;d) dispersing said support on a substrate; ande) drying and calcining the product of step (d).
摘要:
A catalytic converter for treating exhaust gas from an internal combustion engine containing a catalyst characterized by having platinum or a platinum alloy dispersed predominately on the exterior surface of molecular sieve crystals. Also provided is a catalyst for such a converter and processes for manufacture of such catalyst. In addition, a process for treating exhaust gas from an internal combustion engine to reduce the amounts of hydrocarbon, carbon monoxide and nitrogen oxides emitted to the atmosphere is included.
摘要:
Removal of carbon monoxide, hydrocarbons, and nitrogen oxides from the exhaust gas from lean-burn, diesel and other engines which produce exhaust gases containing excess oxygen is provided by at least two catalysts in sequence, each capable of reducing nitrogen oxides within a particular range of engine operating temperatures. Oxidation of the remaining reducing gases is also accomplished.
摘要:
In one embodiment, a particulate filter includes a housing and a substrate disposed within the housing, the substrate comprising a catalyst composition comprising a single crystalline phase multiple metal oxide comprising platinum, wherein the substrate is designed such that gas flowing through the substrate, passes through a walls in the substrate prior to exiting the substrate.
摘要:
A process for removal of carbon monoxide, hydrocarbons, and nitrogen oxides from the exhaust gas from lean-burn, diesel and other engines which produce exhaust gases containing excess oxygen is disclosed. An exhaust gas from an engine operating at an air-fuel ratio above about 18 is contacted with a multi-component catalyst having at least two catalytic components, each capable of reducing nitrogen oxides within a range of exhaust gas temperatures that is different from the range of exhaust gas temperatures within which each other component is capable of reducing nitrogen oxides. Oxidation of the remaining reducing gases is also accomplished. One example of a two catalytic component catalyst of this invention has a first component of Au supported on alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 600° C. and 900° C., and a second component of Pt supported on Y-zeolite, which reduces nitrogen oxides at exhaust gas temperatures below 600° C.; an example of a three catalytic component catalyst of this invention has a first component of CoO supported on &ggr;-alumina, which reduces nitrogen oxides at exhaust gas temperatures above about 475° C., a second component of an alloy of Pt, Rh and Co supported on BaO2-stabilized &dgr;-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 315° C. and about 475° C. and a third component of an alloy of Pt and Rh supported on &ggr;-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 200° C. and about 425° C.
摘要:
Methods of making substantially phase-pure and thermally stable crystalline alumina compositions stabilized with an oxide of silicon, germanium, phosphorus, arsenic or a mixture thereof. Also provided are crystalline alumina compositions and catalyst supports made using these methods.
摘要:
New thermally- and hydrothermally-stable .delta.-alumina compositions stabilized with an oxide of silicon, germanium, phosphorus, arsenic or a mixture thereof and methods of preparation of same are provided. Also provided are catalyst supports and catalysts made using these stabilized .delta.-alumina compositions, methods for making same, and methods for treating the exhaust gas from an internal combustion engine using such catalysts.
摘要:
The present invention is a barium-containing alumina with the X-ray pattern of the FIGURE. The alumina may be synthesized by simultaneously adding a polyether or a polyalcohol and an aqueous solution of a water soluble barium carboxylate to an aqueous boehmite sol or suspension to form a gel, the gel having a polyether or polyalcohol content of about 2 wt. % to about 26 wt. %, preferably about 10 wt. % to about 20 wt. %. The gel is then dried and calcined to convert it to an essentially pure barium-containing delta alumina. The alumina may be optionally hydrothermally treated to induce further crystallization. The final product contains about 2 wt. % to about 18 wt. % Ba, preferably about 8 wt. % to about 12 wt. %.
摘要:
The present invention relates to catalyst support comprising an inorganic oxide, preferably alumina, and zeolite in the proton form and having a high Si/Al ratio, wherein the zeolite is selected from those protonated zeolites that would exhibit a high Na/Al mole ratio if treated with a solution of sodium nitrate until all sites that will accept a sodium ion have done so. This invention also relates to catalyst that is made from such support, to a method of treating exhaust gas from “lean-burn” engines using catalyst of this invention, and to a method for determining if a zeolite is a suitable support component.
摘要:
Removal of carbon monoxide, hydrocarbons, and nitrogen oxides from the exhaust gas from lean-burn, diesel and other engines which produce exhaust gases containing excess oxygen is provided by a multi-component catalyst having at least two catalytic components, each capable of reducing nitrogen oxides within a range of exhaust gas temperatures that is different from the range of exhaust gas temperatures within which each other component is capable of reducing nitrogen oxides. Oxidation of the remaining reducing gases is also accomplished. One example of a two catalytic component catalyst of this invention has a first component of Au supported on alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 600.degree. C. and 900.degree. C., and a second component of Pt supported on Y-zeolite, which reduces nitrogen oxides at exhaust gas temperatures below 600.degree. C.; an example of a three catalytic component catalyst of this invention has a first component of CoO supported on .gamma.-alumina, which reduces nitrogen oxides at exhaust gas temperatures above about 475.degree. C., a second component of an alloy of Pt, Rh and Co supported on BaO.sub.2 -stabilized .delta.-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 315.degree. C. and about 475.degree. C. and a third component of an alloy of Pt and Rh supported on .alpha.-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 200.degree. C. and about 425.degree. C. A method of selecting such catalysts is also provided.