W. R. Grace & Co.

W.r. Grace & Co. -conn.

Michael V Ernest

Gwan Kim

Moises G Sanchez

James M Maselli

Norman R Laine

Sandra Joan Kempske

Michael Bruce Thomas

Stephen Raymond Schmidt

William A Welsh

Stanislaw Plecha

Dean Alexander Denton

Richard A Carman

Alan W Peters

James Richard Graham

Silica compositions for abrasive systems in dentifrice formulations are disclosed. The silica abrasive system comprises (a) silica gels having a median particle size below 7 microns, a pH of from about 6 to about 11 and powder RDA's of from 100 to about 200 and (b) silica gels or precipitates having a median particle size of 7 microns or greater and powder RDA's of from 50 to about 180. Silica (a) is preferably prepared by contacting a hydrous silica gel with an alkaline medium. Dentifrice compositions comprising the abrasive system has an RDA of 150 or less and PCR's of at least 80 and up to about 150, and an REA of less than about 30 (as measured on the IU scale).

Abrasive silica compositions and dentifrice compositions prepared therefrom

A catalyst for control of hydrocarbon emission with improved resistance to phosphorus, sulfur, halogen and silicon poisoning comprising a refractory oxide support impregnated with 0.5 to 20% by weight chromium oxide or manganese oxide or a mixture thereof, and a catalytically effective amount of one or more platinum group metals. The preferred refractory oxide support is alumina. The preferred platinum group metals include Pt, Pd, Ir and Rh.

Chrome/platinum/palladium catalyst for hydrocarbon emission control

Catalysts which are suitable for auto exhaust use are made with a promoter oxide that is deposited in a concentration gradient. A solution of the promoter oxide precursor, e.g., cerous nitrate solution, is impreganted uniformly into the pore structure of a support which can be in the form of beads or extrudates to a level just below the full incipient wetness. The impregnated support is then treated with a gaseous base such as ammonia, under dynamic conditions such as tumbling (to insure uniformity), which causes the precipitation of the promoter oxide in the form of a radial concentration gradient. The resulting product is then dried and calcined at sufficiently high temperature to effect complete conversion of the promoter precursor to its oxide form, e.g., CeO.sub.2.

Catalyst supports having promoter oxide gradient, resulting catalyst and

A catalyst suitable for use as a three-way catalyst having low H.sub.2 S emissions for emission control and with substantially no ceria present is made with a refractory oxide particle or powder support having deposited thereon about 0.5-20% by weight of a non-rate earth oxide stabilizer, at least 0.5 to about 5% by weight of an alkali metal oxide as a promoter, and a catalytically-effective amount of one or more platinum group metals. The preferred refractory oxide is alumina and the non-rare earth oxide stabilizer can be an oxide such as ZrO.sub.2, MgO, CaO, SnO, CaO, Y.sub.2 O.sub.3, TiO.sub.2, ZnO, B.sub.2 O.sub.3, P.sub.2 O.sub.5, SnO.sub.2, Bi.sub.2 O.sub.3, or SiO.sub.2 with the preferred oxide being zirconia.

Auto exhaust catalyst composition having low H.sub.2 S emissions and

A catalyst, which is capable of controlling not only HC, CO and NOx, but also H.sub.2 S emission from the tail pipe of catalytic converter-equipped automobiles, is made of noble metals promoted with ceria-rich rare earth oxides, preferably doubly promoted along with alkali metal oxides, and oxides of nickel and/or iron as an H.sub.2 S gettering ingredient. The oxides of nickel and/or iron are present in an H.sub.2 S gettering effective amount and in an amount up to 10 wt %. The alumina support can have additionally from 0 to 20% SiO.sub.2 present.

Catalysts for controlling auto exhaust emissions including hydrocarbon,

Alumina supported platinum-group metal pelleted catalysts are made which exhibit excellent performance and which have unique Pt concentration profiles. The catalysts are doubly promoted with ceria and alkali metal oxides, especially ceria along with lithia, and can optionally have nickel (oxide) as a base metal catalytic ingredient. The unique Pt profile is obtained by adding at least part of the Rh component separately from any other Pt group metals.

Doubly promoted platinum group metal catalysts for emission control and

Alumina supported platinum-group metal catalysts exhibit exceptionally good performance and durability when the support is sequentially modified to include support stabilization by lanthana or lanthana-rich rare earth oxides, double promotion by ceria and alkali metal oxides, especially ceria along with lithia, and optionally nickel (oxide) as a base metal catalytic ingredient. For a pelleted Rh containing catalyst to exhibit such an outstanding performance at least part of the Rh component is added separately from any other Pt group metals.

Stabilized and doubly promoted platinum group metal catalysts for

A high temperature stable catalyst is made with fine particles of a base metal such as chromium, hafnium and niobium or their oxides dispersed throughout a matrix made of composite particles having at least one platinum group metal on a ceria promoted, high temperature chemically stabilized refractory oxide powder. The refractory oxide powder can be either alumina, alumina powder which has been calcined at a temperature near incipient alpha alumina formation, silica-alumina or zirconia. The base metal or base metal oxide comprises about 15% to 90% by weight of the total weight and the platinum group metal comprises 0.05% to 10% by weight of the total weight. The catalyst composition can be applied as a washcoat to conventional substrates or it can be formed into shaped catalysts. The washcoat is made by mixing together one slip containing the composite particles with a second slip containing the base metal or base metal oxide particles.

Catalyst composition for ultra high temperature operation

Alumina particle catalysts which can be used for auto emission control and especially as a three-way catalyst have increased performance. The alumina particles which are preferably spheroids have a low compacted bulk density of about 20 to 36 pounds per cubic foot and a smaller size on the order of less than 2.6 mm for the preferred spheroids. The spheroid embodiment also has a high crush strength. Because of the small size the ratio of the geometric surface area to the bulk volume (GSA/BV) is at least about 14 cm.sup.2 /cm.sup.3. These alumina particles are impregnated with a catalytically-effective amount of one or more platinum group metals such as platinum, palladium or rhodium and additional promoters can also be added. In the preferred embodiment the alumina particles have a GSA/BV ratio of from about 17 to 25 cm.sup.2 /cm.sup.3 for substantially improved performance.

Small bead auto exhaust catalyst

Catalysts are made from supports which are doubly promoted with ceria and an alkali metal oxide by adding these promoters and the catalytic noble metal components in a specified order. The ceria is first applied to the support. It can be applied in a salt form such as cerous nitrate. This impregnated support is then calcined to form a deposit of ceria. Next, solutions bearing the noble metals are applied to the ceria-promoted support and with these solutions the alkali metal component is applied. After subsequent elevated temperature activation, the alkali metal component is converted to an alkali metal oxide and the noble metals are converted into their metallic or oxide form. When lithium is chosen as the alkali metal promoter, it can alternatively be applied to the support along with the initial ceria promoter. After calcining the support to yield the ceria and lithia promoters, the noble metals can then be deposited and subsequently activated at an elevated temperature. Using this process it is possible to have the noble metals deposited on the support so that their penetration depth is less than 300 microns as measured by the SnCl.sub.2 solution staining method to provide an effective three-way catalyst suitable for use in auto emission control.

Doubly promoted platinum group metal catalysts for emission control

Suspended particles in exhaust gases, such as carbon and lead particles in internal combustion engine exhaust gases, are removed by passing the gases through a coarse filter and then through a fine filter. The filters may comprise a ceramic foam material and a catalyst material effective for the conversion of the carbon particles and/or gaseous pollutants in the exhaust gases to innocuous entities may be deposited on the filters.

Method for exhaust gas treatment

Catalyst composition for exhaust gas treatment

Spheroidal alumina particles have a combination of high macroporosity, surface area, crush strength and low attrition loss and bulk density. The particles are prepared by an improved external gelation oil-drop process. In the process a slurry of alumina, preferably a microcrystalline boehmite-pseudoboehmite intermediate, is prepared in an acidic aqueous medium and droplets of the slurry are passed through air into a column containing an upper body of water-immiscible liquid and ammonia and a lower body of aqueous coagulating agent. Catalysts employing the particles as a support and having catalytic agents distributed at controlled depths in the particle have excellent initial and sustained activity and durability, especially for eliminating pollutants in automotive exhaust streams.

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Baltimore, MD, United States of America

Michael V Ernest