摘要:
A catalyst system for attaining high conversions of NO, HC, and CO in a fuel-lean emission flow (i.e., containing SO.sub.2, H.sub.2 O, H.sub.2, and considerable excess oxygen), the system comprising: (a) a first stage reducing catalyst for treating the nitric oxide emissions, the catalyst containing highly acidic gamma alumina (i.e., with a pH.sub.pzc of less than 3); (b) means for injecting gaseous or liquid reductants into the emission stream prior to entering said first stage catalyst, said first stage catalyst temperature being selected to be in the range of 550.degree.-650.degree. C.; and (c) an oxidation catalyst effective for treating the effluent from the first stage catalyst. Another aspect of this invention is a method of treating the exhaust gas from a fuel-lean emission flow from a fossil-fueled internal combustion engine having a redox ratio of 0.02-0.09, the method comprising: (a) injecting a gaseous or liquid HC or oxygenated HC reductant into the emission stream at a location where the stream is within the temperature range of 550.degree.-650.degree. C.; (b) immediately exposing the injected stream to a first stage catalyst containing acidic gamma alumina with a Ph.sub.pzc of less than 3; and (c) exposing the effluent from the first stage catalyst to an oxidation catalyst that is effective in ensuring that the NO, HC, and CO in the emissions are each converted to at least 80%.
摘要:
The invention is a method for treating exhaust gases generated by a diesel engine by providing a sulfur-tolerant lean-NOx catalyst in an exhaust gas passage of the engine and contacting the catalyst with the exhaust gases. The sulfur-tolerant lean-NOx catalyst comprises a support of titania aerogel; and loaded thereon, using impregnation techniques from a solution of their precursors, at least 0.25 weight percent precious metal selected from platinum, palladium, rhodium, or mixtures thereof. The method converts the hydrocarbons, carbon monoxide and nitrogen oxides into more desirable gases. In particular, the NOx is converted to N.sub.2 and O.sub.2 over the catalyst.
摘要:
A dual-phase zeolite having a transition metal-containing zeolite phase and a transition metal-containing oxide phase. The catalytic material may be an intimate mixture of a phase-layered structure of a first phase constituted preferably of a copper-containing high silica zeolite and a second phase constituted of copper-containing zirconia.Methods are also disclosed for making a single-stage catalyst for removing NO.sub.x and HC at high efficiency in an oxygen-rich automotive exhaust gas, and for treating the exhaust gas with the dual-phase catalyst above.
摘要:
A catalyst system for attaining high conversions of NO, HC, and CO in a fuel-lean emission flow (i.e., containing SO.sub.2, H.sub.2 O, H.sub.2, and considerable excess oxygen), the system comprising: (a) a first stage reducing catalyst for treating the nitric oxide emissions, the catalyst containing highly acidic gamma alumina (i.e., with a pH.sub.pzc of less than 3); (b) means for injecting gaseous or liquid reductants into the emission stream prior to entering said first stage catalyst, said first stage catalyst temperature being selected to be in the range of 550.degree.-650.degree. C.; and (c) an oxidation catalyst effective for treating the effluent from the first stage catalyst.Another aspect of this invention is a method of treating the exhaust gas from a fuel-lean emission flow from a fossil-fueled internal combustion engine having a redox ratio of 0.02-0.09, the method comprising: (a) injecting a gaseous or liquid HC or oxygenated HC reductant into the emission stream at a location where the stream is within the temperature range of 550.degree.-650.degree. C.; (b) immediately exposing the injected stream to a first stage catalyst containing acidic gamma alumina with a pH.sub.pzc of less than 3; and (c) exposing the effluent from the first stage catalyst to an oxidation catalyst that is effective in ensuring that the NO, HC, and CO in the emissions are each converted to at least 80%.
摘要:
A three-way catalyst system for treating the exhaust stream of a compressed natural gas (CNG) fueled engine operating slightly rich of stoichiometry, the said catalyst system providing high conversions and low light-off temperature for the removal of HC, CO, and NO.sub.x. A high surface area gamma alumina support is impregnated with an intimate mixture of 0.2-30% Pd and 0.5-20% La.sub.2 O.sub.3, the Pd being in crystalline form with particle size in the range of 5-500 angstroms.A method of making such catalyst system comprising sequentially impregnating a high surface area gamma alumina support with lanthana and palladium by incipient wetness techniques, such techniques comprising the procedure of contacting alumina first with a lanthanum nitrate solution of desired concentration to obtain 0.5-20% lanthana, contacting the lanthana impregnated alumina with a palladium nitrate solution of desired concentration to obtain a 0.2-30% palladium content in the catalyst, each of said steps being separated by drying and calcination.A method of treating exhaust gas from a CNG fueled engine with the catalyst system described above, comprising: (a) operating said engine at slightly rich of stoichiometry; (b) exposing such catalyst to the exhaust gases in the range of 400.degree.-750.degree. C. and at a space velocity in the range of 0-100K hr.sup.-1, said exhaust gas being converted at an efficiency greater than 90% for each of NO, CO, and CH.sub.4.
摘要:
This invention is directed to a shelf-stable, powder composition adapted to form a high T.sub.g, thermally stable, impact resistant thermoset material. The composition consists essentially of a mixture of an allyl-functional prepolymer component and polymaleimide component. The allyl-functional prepolymer component is the reaction product of an aromatic allyl-functional compound and a modifying compound wherein the compounds contain mutually reactive funtionalities such as an aromatic allyl-functional epoxide compound and a modifying amine compound.
摘要:
This invention relates to an aqueous composition useful to deposit a corrosion inhibiting and adhesion promoting coating on a corrodible metal substrate and a method for doing same. The composition has a pH of between about 2 and about 10 and comprises water-soluble or water-dispersible metal-chelating diphenolamine compounds.
摘要:
This invention is directed to the use of particularly defined epoxy-amine compositions as a protective coating on metals which are exposed to a high temperature, corrosive environment. The metal may be that employed in motor vehicle exhaust system components, such as mufflers and tailpipes. The epoxy-amine compositions comprises epoxy resin component, aromatic amine component, optionally, acid component selected from polycarboxylic acid and anhydrides thereof and optionally, polyol component.
摘要:
This invention relates to a water-soluble or water-dispersible diphenolamine oligomeric metal-chelating compound, method for making same, aqueous composition comprising the compound useful to deposit a corrosion preventive and adhesion promoting coating on a metal substrate and a method for doing same. The composition has a pH of between about 2 and about 10.
摘要:
Crosslinked, preferably acrylic, polymer particles characterized in that the particles formed by free radical addition polymerization of:(a) between about 0.8 and about 20 weight percent each of first and second ethylenically saturated monomers each bearing functionality capable of crosslinking reaction with the other; and(b) between about 98.4 and about 60 weight percent of at least one other monoethylenically unsaturated monomer;in the presence of (I) an organic liquid which is a solvent for the polymerizable monomers, but a non-solvent for the resultant polymer, and (II) polymeric dispersion stabilizer containing at least two segments with one segment being solvated by the organic liquid and the second segment being of different polarity than the first segment and relatively insoluble in the organic liquid, wherein the reaction is carried out at elevated temperatures such that the dispersion polymer forms and then is crosslinked, wherein the percursor of the first segment of the stabilizer comprises a long chain hydrocarbon molecule having only one reactive group per molecule.