Abstract: A process for preparing a silver-containing catalyst for the selective oxidation of ethylene to ethylene oxide including the steps of: (a) providing a multimodal support, (b) preparing an impregnation solution comprising a silver component, (c) impregnating, at least once, the multimodal support of step (a) with the silver-containing impregnation solution of step (b) to form an impregnated support; (d) subjecting the impregnated multimodal support from step (c) to a removal means, such as a centrifuge, at least once, for a time sufficient to remove impregnated silver impregnation solution from the multimodal support and to control the amount of silver in the pores of the multimodal support by selectively removing impregnated silver impregnation solution from a set of larger pores in the multimodal support; (e) roasting, at least once, the multimodal support after the step (d); (f) optionally, repeating the impregnation step (c), (g) optionally, repeating the centrifugation step (d), and (h) optionally, repeat

Abstract: A process for preparing a silver-containing catalyst for the selective oxidation of ethylene to ethylene oxide including the steps of: (a) providing a multimodal support, (b) preparing an impregnation solution comprising a silver component, (c) impregnating, at least once, the multimodal support of step (a) with the silver-containing impregnation solution of step (b) to form an impregnated support; (d) subjecting the impregnated multimodal support from step (c) to a removal means, such as a centrifuge, at least once, for a time sufficient to remove impregnated silver impregnation solution from the multimodal support and to control the amount of silver in the pores of the multimodal support by selectively removing impregnated silver impregnation solution from a set of larger pores in the multimodal support; (e) roasting, at least once, the multimodal support after the step (d); (f) optionally, repeating the impregnation step (c), (g) optionally, repeating the centrifugation step (d), and (h) optionally, repeat

Abstract: A process for preparing a silver-containing catalyst for the selective oxidation of ethylene to ethylene oxide including the steps of: (a) providing a multimodal support, (b) preparing an impregnation solution comprising a silver component, (c) impregnating, at least once, the multimodal support of step (a) with the silver-containing impregnation solution of step (b) to form an impregnated support; (d) subjecting the impregnated multimodal support from step (c) to a removal means, such as a centrifuge, at least once, for a time sufficient to remove impregnated silver impregnation solution from the multimodal support and to control the amount of silver in the pores of the multimodal support by selectively removing impregnated silver impregnation solution from a set of larger pores in the multimodal support; (e) roasting, at least once, the multimodal support after the step (d); (f) optionally, repeating the impregnation step (c), (g) optionally, repeating the centrifugation step (d), and (h) optionally, repeat

Abstract: A porous ceramic composition having improved thermal stability is comprised of ceramic grains bonded together by grain boundary phase comprised of silica, yttrium and oxygen wherein the amount of alkali metals, alkaline earth metals and other transition metals not including rare earth metals is at most 2% by weight of the grain boundary phase.

Abstract: A porous ceramic composition having improved thermal stability is comprised of ceramic grains bonded together by a grain boundary phase comprised of silica, rare earth element that is Eu, Gd, Nd or mixture thereof and oxygen and optionally yttrium, wherein the grain boundary phase has a amount of an alkali, an alkaline earth metal and a transition metal other than yttrium that is at most 2% by weight of the grain boundary phase.

Abstract: A porous ceramic composition having improved thermal stability is comprised of ceramic grains bonded together by grain boundary phase comprised of silica, yttrium and oxygen wherein the amount of alkali metals, alkaline earth metals and other transition metals not including rare earth metals is at most 2% by weight of the grain boundary phase.

Abstract: A porous ceramic composition having improved thermal stability is comprised of ceramic grains bonded together by a grain boundary phase comprised of silica, rare earth element that is Eu, Gd, Nd or mixture thereof and oxygen and optionally yttrium, wherein the grain boundary phase has a amount of an alkali, an alkaline earth metal and a transition metal other than yttrium that is at most 2% by weight of the grain boundary phase.

Abstract: Densified composites of a metal such as copper or aluminum with a titanium-silicon-carbide or titanium-aluminum-carbide ceramic material are prepared by forming the ceramic material into a body, and infiltrating the body with the molten metal. The metal is able to rapidly penetrate into void spaces, between grain boundaries and even into the crystal structure of the ceramic grains to form a composite. The starting ceramic material may be previously densified, in which case various types of gradient structures can be produced easily. The process can be operated at low pressures, and so the hot pressing methods that normally must be used to densify these ceramic materials can be avoided.

Abstract: A method of forming a porous mullite composition of acicular mullite grains having improved properties is described, where the mullite is formed at some time in the presence of a fluorine containing gas. For example, it has been discovered that improved properties may result from heating the mullite to a high temperature in an atmosphere selected from the group consisting of water vapor, oxygen, an inert gas or mixtures thereof or forming the mullite composition from precursors having an Al/Si ratio of at most 2.95.

Abstract: Densified composites of a metal such as copper or aluminum with a titanium-silicon-carbide or titanium-aluminum-carbide ceramic material are prepared by forming the ceramic material into a body, and infiltrating the body with the molten metal. The metal is able to rapidly penetrate into void spaces, between grain boundaries and even into the crystal structure of the ceramic grains to form a composite. The starting ceramic material may be previously densified, in which case various types of gradient structures can be produced easily. The process can be operated at low pressures, and so the hot pressing methods that normally must be used to densify these ceramic materials can be avoided.

Abstract: A method of forming a porous mullite composition of acicular mullite grains having improved properties is described, where the mullite is formed at some time in the presence of a fluorine containing gas. For example, it has been discovered that improved properties may result from heating the mullite to a high temperature in an atmosphere selected from the group consisting of water vapor, oxygen, an inert gas or mixtures thereof or forming the mullite composition from precursors having an Al/Si ratio of at most 2.95.

Abstract: A method of forming a porous mullite composition of acicular mullite grains having improved properties is described, where the mullite is formed at some time in the presence of a fluorine containing gas. For example, it has been discovered that improved properties may result from heating the mullite to a high temperature in an atmosphere selected from the group consisting of water vapor, oxygen, an inert gas or mixtures thereof or forming the mullite composition from precursors having an AL/Si ratio of at most 2.95.