The present invention relates to a dry refractory particulate composition comprising a zeolithic microstructure, to a green body and to a refractory lining formed therefrom, and to uses thereof.

Abrasive particles include: 0.50 to 5.00 weight percent of seed particles for alpha-alumina formation selected from the group consisting of alpha-Fe.sub.2O.sub.3 seed particles, alpha-Al.sub.2O.sub.3 seed particles, and combinations thereof; 0.50 to 5.00 weight percent of MgO; 0.02 to 0.40 weight percent of Li.sub.2O or a molar equivalent amount of at least one alkali metal oxide selected from the group consisting of: Na.sub.2O; K.sub.2O; combinations of Na.sub.2O and Li.sub.2O; combinations of K.sub.2O and Li.sub.2O; combinations of Na.sub.2O and K.sub.2O; and combinations of Li.sub.2O, Na.sub.2O, and K.sub.2O; and 91.08 to 99.48 weight percent of Al.sub.2O.sub.3. Methods of making the abrasive particles and abrasive articles incorporating them are also disclosed.

An alumina sintered body according to the present invention has a degree of c-plane orientation of 90% or more as determined by Lotgering's method from an X-ray diffraction profile obtained by irradiating a plate surface with X-rays in a range of 2=20 to 70. The alumina sintered body has no pores when a cross-sectional surface formed in a direction perpendicular to the plate surface is polished using an Ar.sup.+ ion beam and a mask and is examined under a scanning electron microscope at a magnification of 5,000 times. The alumina sintered body has a total mass fraction of impurity elements other than Mg and C of 100 ppm or less. This alumina sintered body has a high degree of orientation, high density, and high purity and thus has a higher optical translucency than those known in the art.

In a monolithic refractory, in terms of a proportion in 100 mass % of a refractory raw material having a grain size of 8 mm or smaller, an amount of Ca.sub.XSr.sup.1XAl.sub.2O.sub.4 (where, 0X0.5) is 0.5 mass % or more and 10 mass % or less, and a polyvalent metal salt of oxycarboxylic acid is 0.05 mass % or more and 1.0 mass % or less.

A catalyst support comprising at least 85 wt.-% of alpha-alumina and having a pore volume of at least 0.40 mL/g, as determined by mercury porosimetry, and a BET surface area of 0.5 to 5.0 m.sup.2/g, wherein the catalyst support is a tableted catalyst support comprising, based on the total weight of the catalyst support, less than 500 ppmw of potassium. The invention moreover relates to a process for producing a tableted alpha-alumina catalyst support, which comprises i) forming a free-flowing feed mixture comprising i-a) at least one aluminum compound which is thermally convertible to alpha-alumina, the aluminum compound comprising a transition alumina and/or an alumina hydrate; and i-b) 30 to 120 wt.-%, relative to i-a), of a pore-forming material; ii) tableting the free-flowing feed mixture to obtain a compacted body; and iii) heat treating the compacted body at a temperature of at least 1100? C., to obtain the tableted alpha-alumina catalyst support. The invention further relates to a compacted body obtained by tableting a free-flowing feed mixture which comprises, relative to the total weight of the free-flowing feed mixture, a) at least one aluminum compound which is thermally convertible to alpha-alumina, the aluminum compound comprising a transition alumina and/or an alumina hydrate; and b) 30 to 120 wt.-%, relative to a), of a pore-forming material. The invention moreover relates to a shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 12 wt.-% of silver, relative to the total weight of the catalyst, deposited on the tableted alpha-alumina catalyst support. The invention also relates to a process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising reacting ethylene and oxygen in the presence of the shaped catalyst body. The invention allows for the use of specific pore-forming materials that are particularly suitable for obtaining an advantageous pore structure while allowing for a catalyst support having high purity.

A method comprising (a) reacting aluminum metal with an acid in the presence of water to provide a first aluminum salt solution comprising an aluminum salt in water, wherein the aluminum salt comprises a reaction product of the acid and the aluminum metal, (b) heating the first aluminum salt solution to provide a mother liquor and solid aluminum salt, (c) optionally, separating the solid aluminum salt from the mother liquor, (d) optionally, dissolving at least a portion of the separated solid aluminum salt with water to provide a second aluminum salt solution, (e) spray roasting the first, or second (if produced), aluminum salt solution to provide an aluminum oxide powder, and (f) washing the aluminum oxide powder, wherein the washed aluminum oxide powder comprises less than about 30 ppmw total metallic and alkyl impurities.

A method for producing a transparent alumina sintered body according to the present invention includes (a) a step of preparing an alumina raw material powder containing a plate-like alumina powder having an aspect ratio of 3 or more and a fine alumina powder having an average particle diameter smaller than that of the plate-like alumina powder so that, when a mixing ratio of the plate-like alumina powder to the fine alumina powder in terms of mass ratio is assumed to be T:(100T), T is 0.001 or more and less than 1, and so that a mass ratio R1 of F relative to A1 in the alumina raw material powder is less than 15 ppm; (b) a step of forming a raw material for forming containing the alumina raw material powder into a compact; and (c) a step of sintering the compact so as to obtain a transparent alumina sintered body.

The present invention relates to a method for obtaining calcium aluminates for metallurgical use from non-saline aluminum slags by means of reactive grinding and thermal treatment.

An extruded, solid honeycomb body comprises a copper-promoted, small pore, crystalline molecular sieve catalyst for converting oxides of nitrogen in the presence of a reducing agent, wherein the crystalline molecular sieve contains a maximum ring size of eight tetrahedral atoms, which extruded, solid honeycomb body comprising: 20-50% by weight matrix component comprising diatomaceous earth, wherein 2-20 weight % of the extruded, solid honeycomb body is diatomaceous earth; 80-50% by weight of the small pore, crystalline molecular sieve ion-exchanged with copper; and 0-10% by weight of inorganic fibres.

A catalyst carrier may include an aluminate based body and may have a specific surface area of not greater than about 20 m.sup.2/g. The aluminate based body may include a hexaaluminate phase.