Abstract: A method of preparing a solid material based on tangled nanotubes and/or nanofibres, includes a step of growing carbon nanofibres and/or nanotubes with restraint in a contained reactor; and the materials thus obtained. The different uses of the materials are also disclosed.

Abstract: In a process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst comprising a metal and a support comprising silicon carbide, the support comprises more than 50% by weight of silicon carbide in the beta form. A process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst the effluent thus obtained are also disclosed.

Abstract: A SiC-based composite material capable of use as an inner coating for an aluminium smelting furnace or as an inner coating for a fused salt electrolytic cell, wherein said composite material has been prepared from a precursor mixture comprising at least one ?-SiC precursor and at least one carbonated resin, and wherein said composite material contains inclusions, and wherein at least one part thereof comprises ?-SiC, in a ?-SiC matrix.

Abstract: The invention relates to a composite formed of a zeolite (such as ZSM-5 zeolite, ?-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 ?-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: The invention relates to a method for obtaining synthesis gas by partial catalytic oxidation, consisting in bringing a hydrocarbon in a gaseous state into contact with an oxidizing gas, and therefore possibly a small amount of water vapor, in the presence of a catalyst comprising at least one silicon carbide at a temperature of more than 800° C. According to the invention, the silicon carbide has a specific surface which is determined by the BET method and which is less than or equal to 100 m2/g, the contact time between the mixture of gaseous hydrocarbon, oxidizing gas and silicon carbide being more than 0.05 seconds and the pressure inside the reactor being greater than atmospheric pressure.

Abstract: In a process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst comprising a metal and a support comprising silicon carbide, the support comprises more than 50% by weight of silicon carbide in the beta form. A process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst the effluent thus obtained are also disclosed.

Abstract: The invention concerns a method for so-called two-phase impregnation of a ?-SiC support with high specific surface area, said method comprising at least the following steps: (a) a first impregnating at least once said support with a polar agent A, (b) a second impregnating which consists in impregnating at least once said support with at least an agent B less polar than agent A. Said method enables the production of novel catalysts for heterogeneous catalysis.

Abstract: The photocatalyst based on a composite WO3—SiC/TiO2 semiconductor and subjected to radiation whose wavelength is at least partly less than 400 nm gives photocatalytic oxidation of volatile organic compounds and leads to their total mineralisation into CO2 and H2O. The process for the photocatalytic purification of industrial, agricultural or domestic gaseous effluent may be conducted at room pressure and temperature. Its conversion rate is high and stable.

Abstract: In a process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst comprising a metal and a support comprising silicon carbide, the support comprises more than 50% by weight of silicon carbide in the beta form. A process for the conversion of carbon monoxide to C2+ hydrocarbons in the presence of hydrogen and of a catalyst the effluent thus obtained are also disclosed.

Abstract: A process for the conversion of methane/carbon dioxide mixtures to a carbon monoxide/hydrogen mixture is provided in which use is made of a catalyst with a support comprising silicon carbide in the beta form.

Abstract: This invention relates to ?-SiC foam parts with a specific surface area preferably equal to at least 5 m2/g and with at least two zones A and B with a different cellular porosity distribution, wherein the parts were made by chemical transformation of a porous precursor medium comprising at least two blocks A? and B?, each having a different cellular porosity distribution, and in that the at least two zones A and B are derived from the chemical transformation of the two blocks A? and B?. This foam, optionally after deposition of an active layer, may be used as a filter medium in cartridges designed for the purification of exhaust gases. The invention also relates to manufacturing processes for preparing such a filter medium.

Abstract: The invention relates to a method for obtaining synthesis gas by partial catalytic oxidation, consisting in bringing a hydrocarbon in a gaseous state into contact with an oxidizing gas, and therefore possibly a small amount of water vapor, in the presence of a catalyst comprising at least one silicon carbide at a temperature of more than 800° C. According to the invention, the silicon carbide has a specific surface which is determined by the BET method and which is less than or equal to 100 m2/g, the contact time between the mixture of gaseous hydrocarbon, oxidizing gas and silicon carbide being more than 0.05 seconds and the pressure inside the reactor being greater than atmospheric pressure.

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.