The present invention is directed to a porous pre-densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 50.0 to 95.0%, relative to the theoretical density of zirconia, and an open porosity of 5 to 50% as well as to a densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 97.0 to 100.0%, relative to the theoretical density of zirconia, and wherein the grains of the ceramic have an average grain size of 50 to 1000 nm, methods for the preparation of the pre-densified and densified ceramics and their use for the manufacture of dental restorations.

The present invention is directed to a porous pre-densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 50.0 to 95.0%, relative to the theoretical density of zirconia, and an open porosity of 5 to 50% as well as to a densified CeO.sub.2-stabilized ZrO.sub.2 ceramic having a density of 97.0 to 100.0%, relative to the theoretical density of zirconia, and wherein the grains of the ceramic have an average grain size of 50 to 1000 nm, methods for the preparation of the pre-densified and densified ceramics and their use for the manufacture of dental restorations.

Disclosed herein is a method comprising disposing a first particle in a reactor; the first particle being a magnetic particle or a particle that can be influenced by a magnetic field, an electric field or a combination of an electrical field and a magnetic field; fluidizing the first particle in the reactor; applying a uniform magnetic field, a uniform electrical field or a combination of a uniform magnetic field and a uniform electrical field to the reactor; elevating the temperature of the reactor; and fusing the first particles to form a monolithic solid.

Disclosed herein is a method comprising disposing a first particle in a reactor; the first particle being a magnetic particle or a particle that can be influenced by a magnetic field, an electric field or a combination of an electrical field and a magnetic field; fluidizing the first particle in the reactor; applying a uniform magnetic field, a uniform electrical field or a combination of a uniform magnetic field and a uniform electrical field to the reactor; elevating the temperature of the reactor; and fusing the first particles to form a monolithic solid.

A cohesive granular material comprises granules made of a stiff substance and having a grain size in the range from 55 m to 2.0 mm; an elastomeric substance connecting the granules, a Young's modulus of the elastomeric substance being at maximum 0.5 times a Young's modulus of the stiff substance; and voids between the granules, the voids being interconnected and providing a fluid permeability to the cohesive granular material.

A cohesive granular material comprises granules made of a stiff substance and having a grain size in the range from 55 m to 2.0 mm; an elastomeric substance connecting the granules, a Young's modulus of the elastomeric substance being at maximum 0.5 times a Young's modulus of the stiff substance; and voids between the granules, the voids being interconnected and providing a fluid permeability to the cohesive granular material.

A method for producing a three-dimensional porous transition alumina catalyst monolith of stacked catalyst fibers, comprising the following steps: a) Preparing a suspension paste in a liquid diluent of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and which suspension can furthermore comprise a binder material in a maximum amount of 20 wt %, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and/or a plasticizer and/or a dopant in a maximum amount of 10 wt %, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, all particles in the suspension having a number average particle size in the range of from 0.05 to 700 m, b) extruding the paste of step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the porous catalyst monolith precursor to remove the liquid diluent, d) performing a temperature treatment of the dried porous catalyst monolith precursor of step c) at a temperature in the range of from 500 to 1000 C., to form the transition alumina catalyst monolith, wherein no temperature treatment of the porous catalyst monolith precursor or porous catalyst monolith at temperatures above 1000 C. is performed and wherein no further catalytically active metals, metal oxides or metal compounds are applied to the surface of the transition alumina precursor particles, the catalyst monolith precursor or transition alumina catalyst monolith. no further catalytically active metals, metal oxides or metal compounds are present in the suspension paste.

A method for producing a three-dimensional porous transition alumina catalyst monolith of stacked catalyst fibers, comprising the following steps: a) Preparing a suspension paste in a liquid diluent of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and which suspension can furthermore comprise a binder material in a maximum amount of 20 wt %, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and/or a plasticizer and/or a dopant in a maximum amount of 10 wt %, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, all particles in the suspension having a number average particle size in the range of from 0.05 to 700 m, b) extruding the paste of step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the porous catalyst monolith precursor to remove the liquid diluent, d) performing a temperature treatment of the dried porous catalyst monolith precursor of step c) at a temperature in the range of from 500 to 1000 C., to form the transition alumina catalyst monolith, wherein no temperature treatment of the porous catalyst monolith precursor or porous catalyst monolith at temperatures above 1000 C. is performed and wherein no further catalytically active metals, metal oxides or metal compounds are applied to the surface of the transition alumina precursor particles, the catalyst monolith precursor or transition alumina catalyst monolith. no further catalytically active metals, metal oxides or metal compounds are present in the suspension paste.

A hydrogen gas producing apparatus includes a porous body (100) and a mixed gas source (300). The porous body (100) is permeable to hydrogen gas and carbon dioxide gas, and has a property of being more permeable to hydrogen gas than carbon dioxide gas. The mixed gas source (300) causes a mixed gas including carbon dioxide gas and hydrogen gas to flow into the porous body (100) under a condition that a pressure gradient represented by (P.sub.1P.sub.2)/L is below 50 MPa/m, where L represents the length of the porous body (100) in a direction in which the mixed gas permeates; P.sub.1 represents an inflow pressure of the mixed gas into the porous body (100); and P.sub.2 represents an outflow pressure thereof from the porous body (100).

A hydrogen gas producing apparatus includes a porous body (100) and a mixed gas source (300). The porous body (100) is permeable to hydrogen gas and carbon dioxide gas, and has a property of being more permeable to hydrogen gas than carbon dioxide gas. The mixed gas source (300) causes a mixed gas including carbon dioxide gas and hydrogen gas to flow into the porous body (100) under a condition that a pressure gradient represented by (P.sub.1P.sub.2)/L is below 50 MPa/m, where L represents the length of the porous body (100) in a direction in which the mixed gas permeates; P.sub.1 represents an inflow pressure of the mixed gas into the porous body (100); and P.sub.2 represents an outflow pressure thereof from the porous body (100).