A process for the preparation of an alumina in the form of beads with a sulphur content in the range 0.001% to 1% by weight and a sodium content in the range 0.001% to 1% by weight with respect to the total mass of said beads is described, said beads being prepared by shaping an alumina gel having a high dispersibility by drop coagulation. The alumina gel is itself prepared using a specific precipitation preparation process in order to obtain at least 40% by weight of alumina with respect to the total quantity of alumina formed at the end of the gel preparation process right from the first precipitation step, the quantity of alumina formed at the end of the first precipitation step possibly even reaching 100%. The invention also concerns the use of alumina beads as a catalyst support in a catalytic reforming process.

An abrasive grain is disclosed and may include a body. The body may define a length (l), a height (h), and a width (w). In a particular aspect, the length is greater than or equal to the height and the height is greater than or equal to the width. Further, in a particular aspect, the body may include a primary aspect ratio defined by the ratio of length:height of at least about 2:1. The body may also include an upright orientation probability of at least about 50%.

A method comprising contacting high-purity acid, high-purity aluminum, and high-purity water to form a first solution in a heated non-contaminating vessel, wherein the aluminum is employed in at least a stoichiometric amount relative to the acid, heating the first solution in a non-contaminating container, to provide a mother liquor and solid aluminum salts, separating the solid aluminum salts from the mother liquor, heating the solid aluminum salts in a non-contaminating crucible, to provide alpha aluminum oxide, and, optionally, washing the alpha aluminum oxide with high-purity water after some or all of the heating of the solid aluminum salts to provide the alpha aluminum oxide.

A system, process and related sintered article are provided. The process includes supporting a piece of inorganic material with a pressurized gas and sintering the piece of inorganic material while supported by the pressurized gas by heating the piece of inorganic material to a temperature at or above a sintering temperature of the inorganic material such that the inorganic material is at least partially sintered forming the sintered article. The inorganic material is not in contact with a solid support during sintering. The sintered article, such as a ceramic article, is thin, has high surface quality, and/or has large surface areas.

The present invention concerns spheroidal alumina particles, catalysts comprising such particles as a support and a process for the production of spheroidal alumina particles, comprising the following steps: a) preparing a suspension comprising water, an acid and at least one boehmite powder for which the ratio of the crystallite dimensions in the [020] and [120] directions obtained using the Scherrer X-ray diffraction formula is in the range 0.7 to 1; b) adding a pore-forming agent, a surfactant and optionally water, or an emulsion comprising at least one pore-forming agent, a surfactant and water to the suspension of step a); c) mixing the suspension obtained in step b); d) shaping the spheroidal particles by the oil-drop method using the suspension obtained in step c); e) drying the particles obtained in step d); f) calcining the particles obtained in step e).

An abrasive grain is disclosed and may include a body. The body may define a length (l), a height (h), and a width (w). In a particular aspect, the length is greater than or equal to the height and the height is greater than or equal to the width. Further, in a particular aspect, the body may include a primary aspect ratio defined by the ratio of length:height of at least about 2:1. The body may also include an upright orientation probability of at least about 50%.

Mesoporous and macroporous hydroconversion catalyst: a predominantly calcined alumina oxide matrix; a hydrogenating-dehydrogenating active phase with at least one VIB metal, optionally at least one VIII metal, optionally phosphorus,
said active phase being at least partly co-mixed in said predominantly calcined alumina oxide matrix.

Preparation process for a residue hydroconversion/hydrotreating catalyst by co-mixing of the active phase with a particular alumina.

Use of the catalyst in hydrotreating processes, in particular hydrotreating of heavy feedstocks.

The invention concerns a process for the preparation of an amorphous mesoporous and macroporous alumina, comprising at least one step for dissolving an acidic precursor of aluminium, a step for adjusting the pH by adding at least one basic precursor to the suspension obtained in step a), a step for co-precipitation of the suspension obtained at the end of step b) by adding at least one basic precursor and at least one acidic precursor to the suspension, a filtration step, a drying step, a shaping step and a heat treatment step.

The invention also concerns an amorphous mesoporous and macroporous alumina with a bimodal pore structure having: a specific surface area S.sub.BET of more than 100 m.sup.2/g; a median mesopore diameter, by volume determined by mercury intrusion porosimetry, of 18 nm or more; a median macropore diameter, by volume determined by mercury intrusion porosimetry, in the range 100 to 1200 nm, limits included; a mesopore volume, as measured by mercury intrusion porosimetry, of 0.7 mL/g or more; and a total pore volume, as measured by mercury porosimetry, of 0.8 mL/g or more.

This application discloses methods and processes for preparation of high purity aluminum hydroxide and high purity aluminum oxide. The method of preparing high purity aluminum hydroxide involves reacting aluminum with water in the presence of one or more catalysts and one or more complexing agents that can react with non-aluminum metal impurities to form soluble complexes for effective removal through rinsing.

There are provided processes for converting alumina into -Al.sub.2O.sub.3 or transition alumina that comprise heating the alumina at a temperature of about 900 C. to about 1200 C. in the presence of steam and optionally at least one gas under conditions suitable to obtain the -Al.sub.2O.sub.3 or transition alumina. For example, the alumina can comprise a transition alumina (such as -Al.sub.2O.sub.3), an amorphous alumina or a mixture thereof.