Abstract: The preparation of graphene, mono-, bi- and multi-layers from graphite-based precursor materials, for example, pencil lead or graphite, by a method of mechanical thinning on the surface of a planar substrate with controlled roughness, followed by sonication in order to collect the graphene deposited on the substrate in a liquid medium. The bearing force during thinning by mechanical friction enables the number of graphene sheets deposited on the surface of the substrate to be controlled.

Abstract: The preparation of graphene, mono-, bi- and multi-layers from graphite-based precursor materials, for example, pencil lead or graphite, by a method of mechanical thinning on the surface of a planar substrate with controlled roughness, followed by sonication in order to collect the graphene deposited on the substrate in a liquid medium. The bearing force during thinning by mechanical friction enables the number of graphene sheets deposited on the surface of the substrate to be controlled.

Abstract: A process for the preparation of dimethyl ether by catalytic dehydration of methanol, in which there is used a catalyst based on a zeolite immobilized on a silicon carbide support, for example a zeolite of type ZSM-5 supported on silicon carbide extrudates or on a silicon carbide cellular foam.

Abstract: A method for inactivating biological agents dispersed within a gaseous medium includes a step which consists in treating the gas flow with a photoactivated semiconductor, in particular with photoactivated titanium oxide. The invention also concerns a device for implementing the method, as well as the method for decontaminating gaseous medium containing harmful, toxic or pathogenic biological agents, such as bacteria.

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: 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: 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 regenerative process for oxidizing H2S contained in low concentration in a gas directly to sulphur including combining the H2S-containing gas with a gas containing free oxygen in an amount to form an O2/H2S-containing gas with an O2/H2S molar ratio ranging from 0.05 to 15; contacting the O2/H2S-containing gas with a catalyst for the selective oxidation of H2S to sulphur, wherein the catalyst includes a catalytically active phase containing at least one oxysulphide of at least one metal selected from the group consisting of nickel, iron, cobalt, copper, chromium, molybdenum and tungsten combined with a silicon carbide support and including a compound of at least one transition metal, at temperatures below the dew point of the sulphur formed by oxidation of H2S and depositing the sulphur on the catalyst; periodically regenerating by flushing the sulphur-laden catalyst using a non-oxidizing gas at temperatures of between 200° C. and 500° C.

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.