The invention concerns a synthesis process of a compound of the following formula (I) or one of the salts thereof,

##STR00001## wherein R represents a COOH, CH.sub.2OH or CHO group, comprising the step according to which the but-3-ene-1,2-diol (BDO) is subjected to an oxidation in the presence of a catalyst, said catalyst comprising an active phase based on at least one noble metal selected from palladium, gold, silver, platinum, rhodium, osmium, ruthenium and iridium, and a support containing alkaline sites.

The invention also concerns the application of this reaction to the preparation of bioavailable compounds of methionine used, in particular, in animal nutrition.

The present invention relates to a process for the preparation of catalyst(s), comprising the cokneading of boehmite with an active phase comprising a salt of heteropolyanion of Keggin and/or lacunary Keggin and/or substituted lacunary Keggin and/or Anderson and/or Strandberg type, and their mixtures, exhibiting, in its structure, molybdenum and cobalt and/or nickel. The present invention also relates to a process for the hydrotreating and/or hydroconversion of a heavy hydrocarbon feedstock in the presence of catalyst(s) prepared according to said process.

The present invention relates to a process for the preparation of catalyst(s), comprising the cokneading of boehmite with an active phase comprising a salt of heteropolyanion of Keggin and/or lacunary Keggin and/or substituted lacunary Keggin and/or Anderson and/or Strandberg type, and their mixtures, exhibiting, in its structure, molybdenum and cobalt and/or nickel. The present invention also relates to a process for the hydrotreating and/or hydroconversion of a heavy hydrocarbon feedstock in the presence of catalyst(s) prepared according to said process.

Methods for making a supported chromium catalyst are disclosed, and can comprise contacting a silica-coated alumina containing at least 30 wt. % silica with a chromium-containing compound in a liquid, drying, and calcining in an oxidizing atmosphere at a peak temperature of at least 650° C. to form the supported chromium catalyst. The supported chromium catalyst can contain from 0.01 to 20 wt. % chromium, and typically can have a pore volume from 0.5 to 2 mL/g and a BET surface area from 275 to 550 m.sup.2/g. The supported chromium catalyst subsequently can be used to polymerize olefins to produce, for example, ethylene-based homopolymers and copolymers having high molecular weights and broad molecular weight distributions.

Methods for making a supported chromium catalyst are disclosed, and can comprise contacting a silica-coated alumina containing at least 30 wt. % silica with a chromium-containing compound in a liquid, drying, and calcining in an oxidizing atmosphere at a peak temperature of at least 650° C. to form the supported chromium catalyst. The supported chromium catalyst can contain from 0.01 to 20 wt. % chromium, and typically can have a pore volume from 0.5 to 2 mL/g and a BET surface area from 275 to 550 m.sup.2/g. The supported chromium catalyst subsequently can be used to polymerize olefins to produce, for example, ethylene-based homopolymers and copolymers having high molecular weights and broad molecular weight distributions.

A system for continuously treating recycled polymeric material includes a hopper configured to feed the recycled polymeric material into the system. An extruder can turn the recycled polymeric material in a molten material. In some embodiments, the extruder uses thermal fluids, electric heaters, and/or a separate heater. The molten material is depolymerized in a reactor. In some embodiments, a catalyst is used to aid in depolymerizing the material. In certain embodiments, the catalyst is contained in a permeable container. The depolymerized molten material can then be cooled via a heat exchanger. In some embodiments, multiple reactors are used. In certain embodiments, these reactors are connected in series. In some embodiments, the reactor(s) contain removable static mixer(s) and/or removable annular inserts.

A system for continuously treating recycled polymeric material includes a hopper configured to feed the recycled polymeric material into the system. An extruder can turn the recycled polymeric material in a molten material. In some embodiments, the extruder uses thermal fluids, electric heaters, and/or a separate heater. The molten material is depolymerized in a reactor. In some embodiments, a catalyst is used to aid in depolymerizing the material. In certain embodiments, the catalyst is contained in a permeable container. The depolymerized molten material can then be cooled via a heat exchanger. In some embodiments, multiple reactors are used. In certain embodiments, these reactors are connected in series. In some embodiments, the reactor(s) contain removable static mixer(s) and/or removable annular inserts.

Methods for making a supported chromium catalyst are disclosed, and can comprise contacting a silica-coated alumina containing at least 30 wt. % silica with a chromium-containing compound in a liquid, drying, and calcining in an oxidizing atmosphere at a peak temperature of at least 650° C. to form the supported chromium catalyst. The supported chromium catalyst can contain from 0.01 to 20 wt. % chromium, and typically can have a pore volume from 0.5 to 2 mL/g and a BET surface area from 275 to 550 m.sup.2/g. The supported chromium catalyst subsequently can be used to polymerize olefins to produce, for example, ethylene-based homopolymers and copolymers having high molecular weights and broad molecular weight distributions.

Methods for making a supported chromium catalyst are disclosed, and can comprise contacting a silica-coated alumina containing at least 30 wt. % silica with a chromium-containing compound in a liquid, drying, and calcining in an oxidizing atmosphere at a peak temperature of at least 650° C. to form the supported chromium catalyst. The supported chromium catalyst can contain from 0.01 to 20 wt. % chromium, and typically can have a pore volume from 0.5 to 2 mL/g and a BET surface area from 275 to 550 m.sup.2/g. The supported chromium catalyst subsequently can be used to polymerize olefins to produce, for example, ethylene-based homopolymers and copolymers having high molecular weights and broad molecular weight distributions.

A oxygen transfer agent useful for the oxidative dehydrogenation of saturated hydrocarbons includes at least one mixed oxide derived from manganese or compounds thereof, as well as a promoter, such as tungsten and/or phosphorus. The oxygen transfer agent may also include an alkali metal or compounds thereof, boron or compounds thereof, an oxide of an alkaline earth metal, and an oxide containing one or more of one or more of manganese, lithium, boron, and magnesium. A reactor is at least partially filled with the oxygen transfer agent in the form of a fixed or circulating bed and provides an unsaturated hydrocarbon product, such as ethylene and/or propylene. The oxygen transfer agent may be regenerated using oxygen.