W. R. Grace Co.-Conn.

Alliedsignal Inc.

Jeffrey P Solar

Jean Willem Beeckman

Wie-Hin Pan

Louis Hegedus

Jean Yamanis

Anthony J Fanelli

Beili L Wu

This invention provides a compound having the formula LnSi.sub.3 N.sub.5 wherein Ln is selected from the group consisting of scandium, yttrium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. In addition, there is provided a method for making the compound Ln'Si.sub.3 N.sub.5 wherein Ln' is a radical selected from the group consisting of lanthanum, scandium, yttrium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, comprising the step of reacting SiO.sub.z, Ln'.sub.x O.sub.y in a nitrogen atmosphere in the presence of carbon at a temperature of from 1200.degree. C. to about 2000.degree. C. for at least 2 hrs., x being an integer equal to or greater than 2, y being an integer equal to or greater than 3, and z being an integer selected from 1 and 2, with the proviso that x and y are selected to result in a stable compound of Ln'.sub.x O.sub.y.

Ternary silicon-rare earth nitrides and process for their preparation

Catalysts for the selective catalytic reduction of NOx by ammonia are made from porous formed supports having a certain fraction of the pores with pore diameters larger than 600 Angstrom units. Thus macropores can be introduced in a formed TiO.sub.2 support by adding burnout materials prior to forming the titania into the formed support. Then conventional DeNOx catalytic metals are added. Barium sulfate can be added to the surface of the porous inorganic oxide to make an improved support.

Catalysts for selective catalytic reduction denox technology

Catalysts for the selective catalytic reduction of NOx by ammonia are made from porous formed supports having a certain fraction of the pores with pore diameters larger than 600 Angstrom units. Thus macropores can be introduced in a formed TiO.sub.2 support by adding burnout materials or some inorganic oxide prior to forming the titania into the formed support. Alternatively, titania is precipitated onto a porous inorganic oxide such as SiO.sub.2, Al.sub.2 O.sub.3, ZrO.sub.2, AlPO.sub.4, Fe.sub.2 O.sub.3 and B.sub.2 O.sub.3 to form the support. Then conventional DeNOx catalytic metals are added. The support can be made by first impregnating the inorganic oxide particles with titania via a soluble precursor, forming titania and then shaping the coated particles into the desired shape such as a monolith. In a second embodiment, the inorganic oxide particles are first formed into the desired shape and then impregnated with the titania forming material. Barium sulfate can be added to the surface of the porous inorganic oxide to make an improved support.

Process using catalysts for selective catalytic reduction denox

Catalysts for the selective catalytic reduction of NOx by ammonia are made from porous formed supports having a certain fraction of the pores with pore diameters larger than 600 Angstrom units. Thus macropores can be introduced in a formed TiO.sub.2 support by adding burnout materials or some inorganic oxide prior to forming the titania into the formed support. Alternatively, titania is precipitated onto a porous inorganic oxide such as SiO.sub.2, Al.sub.2 O.sub.3, ZrO.sub.2, AlPO.sub.4, Fe.sub.2 O.sub.3 and B.sub.2 O.sub.3 to form the support. Then conventional DeNOx catalytic metals are added. The support can be made by first impregnating the inorganic oxide particles with titania via a soluble precursor, forming titania and then shaping the coated particles into the desired shape such as a monolith. In a second embodiment, the inorganic oxide particles are first formed into the desired shape and then impregnated with the titania forming material. Barium sulfate can be added to the surface of the porous inorganic oxide to made an improved support.

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Silver Spring, MD, United States of America

Jeffrey P Solar