Abstract: A composite comprising a support activated by impregnation and carbon nanotubes or nanofibers formed by vapor deposition, wherein the weight of said carbon nanotubes or nanofibers formed on the said support is at least equal to 10.

Abstract: The invention relates to a composite formed of a zeolite (such as ZSM-5 zeolite, P-zeolite and silicalite) deposited on a rigid support, wherein the rigid support comprises silicon carbide (SiC) with a specific surface area BET of at least 5 m2/g. Preferably, the support is a &bgr;-SiC foam with a specific area of between 10 and 500 m2/g. This composite may be used as a catalyst and/or a catalyst support for chemical reactions in a gas or liquid medium. For example materials of the present invention are useful for example, in connection with cracking, acylation, alkylation and/or isomerization of hydrocarbons.

Abstract: A molybdenum-loaded crystalline aluminosilicate molecular sieve that exhibits the MFI crystal structure and has a silica-to-alumina ratio of about 50:1 is useful for aromatizing a hydrocarbon feed stream. The crystalline aluminosilicate preferably has an external surface acidity selectively passivated by means of an amorphous silica layer. A process for the aromatization of methane comprises a one- or multi-step process that contacts a feed stream comprising at least methane with a catalyst composition comprising the preferred molecular sieve, at hydrocarbon conversion conditions that include a temperature of 600-800° C., a pressure of less than 5 atmospheres absolute and a Weight Hourly Space Velocity (WHSV) of 0.1-10 h−1, with the external surface acidity of the crystalline aluminosilicate preferably selectively passivated by an amorphous silica layer. C6-plus aromatic hydrocarbons are preferably recovered from the process by means of an intermediate separation step.

Abstract: A molybdenum-loaded crystalline aluminosilicate molecular sieve that exhibits the MFI crystal structure and has a silica-to-alumina ratio of about 50:1 is useful for aromatizing a hydrocarbon feed stream. The crystalline aluminosilicate preferably has an external surface acidity selectively passivated by means of an amorphous silica layer. A process for the aromatization of methane comprises a one- or multi-step process that contacts a feed stream comprising at least methane with a catalyst composition comprising the preferred molecular sieve, at hydrocarbon conversion conditions that include a temperature of 600-800° C., a pressure of less than 5 atmospheres absolute and a Weight Hourly Space Velocity (WHSV) of 0.1-10 h−1, with the external surface acidity of the crystalline aluminosilicate preferably selectively passivated by an amorphous silica layer. C6-plus aromatic hydrocarbons are preferably recovered from the process by means of an intermediate separation step.

Abstract: A process for catalytically oxidizing H2S contained in a gas directly to sulphur containing the following steps: combining the H2S-containing gas with a gas containing free oxygen in an amount to produce an oxygen-enriched H2S-containing gas having O2/H2S molar ratio ranging from about 0.05 to about 15; and contacting the oxygen-enriched H2S-containing gas with a catalyst for selective oxidation of H2S to sulphur, wherein the catalyst includes a catalytically active phase combined with a silicon carbide-based support and wherein the active phase of the catalyst consists of at least one oxysulphide of at least one metal selected from the group consisting of iron, copper, nickel, cobalt, chromium, molybdenum and tungsten, at a temperature above the dew point of sulphur formed during H2S oxidation.

Abstract: A process for catalytically oxidizing the H.sub.2 S present at low concentration in a gas to sulphur wherein the gas together with a gas containing free oxygen in a quantity to provide and O.sub.2 to H.sub.2 S mole ratio ranging from 0.05 to 10 are contacted with a catalyst for selectively oxidizing H.sub.2 S to sulphur, the catalyst comprising a support based on silicon carbide associated with a catalytic active phase containing at least one transition metal such as Fe, Ni, Cr, Co, Cu, Ag, Mn, Mo, Ti, W or V, in a form of a metal compound and/or in the elemental state. Prior to treating the gas, the oxidation catalyst is subjected to an activation treatment which loads the active phase of the catalyst to provide maximum sulphurization of the metal of the catalyst. In an alternate embodiment, the oxidation of the H.sub.2 S is performed below the dew point of the sulphur. In another embodiment, the oxidation is performed at a temperature above the dew point of sulphur and in particular between 200.degree. C.

Abstract: A catalyst for chemical and petrochemical reactions and a process for its production. The catalyst comprises an oxide of one of the transition metals, rare earth elements, or actinide elements, e.g., molybdenum, having on its surface carbides and oxycarbides, the core being the metal or the metal oxide. In the process for catalyst production, the reaction gas mixture containing carbon products is passed onto the oxide, leading to a progressive carburization of the surface of the oxide and to a progressive increase in the efficiency of the catalyst.

Abstract: A method of producing heavy metal carbides of high specific surface area characterised in that a compound in the gazeous state of said heavy metal is caused to react with reactive carbon having a specific surface area at least equal to 200 m.sup.2.g.sup.-1 at a temperature comprised between 900.degree. and 1400.degree. C., and thus obtained carbides.

Abstract: A method of producing heavy metal carbides of high specific surface area characterized in that a compound in the gazeous state of said heavy metal is caused to react with reactive carbon having a specific surface area at least equal to 200 m.sup.2. g.sup.-1 at a temperature comprised between 900.degree. and 1400.degree. C., and thus obtained carbides.

Abstract: Process for activating carbides of heavy metals with a large specific surface with a view to their use as a catalyst for chemical or petrochemical reactions consisting of treating the said carbides by managed oxidation under an oxidizing gas stream at a temperature between 250.degree. and 450.degree. C., maintaining the temperature for at least 3 hours and then cooling to ambient temperature, still under said oxidizing stream.