The carbon nanotubes according to the present invention can provide higher conductivity by allowing the BET and crystal size to satisfy the conditions expressed by formula 1 below, and consequently, can improve the conductivity of a carbon composite material containing the carbon nanotubes.

L.sub.c[Specific surface area of CNT (cm.sup.2/g)].sup.1/2>80[Formula 1] wherein, L.sub.c is crystal size measured by X-ray diffraction.

A catalyst for selectively oxidizing hydrogen sulfide to element sulfur, catalyst for burning tail-gas, and process for deeply catalytically oxidizing hydrogen sulfide to sulfur are disclosed. The catalyst for selectively oxidizing hydrogen sulfide to element sulfur is prepared by: 10-34% of iron trioxide and 60-84% of anatase titanium dioxide, and the balance being are auxiliary agents. Also a catalyst for burning tail-gas is prepared by: 48-78% of iron trioxide and 18-48% of anatase titanium dioxide, and the balance being auxiliary agents. The catalyst of the present invention has high selectivity and high sulfur recovery rate. An isothermal reactor and an adiabatic reactor of the present invention are connected in series and are filled with the above two catalysts for reactions, thus reducing total sulfur in the vented gas while having a high sulfur yield and conversion rate.

An artificial photosynthesis module includes an oxygen generation electrode having a first photocatalyst layer that decomposes water with light to generate oxygen, and has a first substrate, a first conductive layer, a first photocatalyst layer, and a first co-catalyst, and a hydrogen generation electrode that decomposes water with light to generate hydrogen and has a second substrate, a second conductive layer, a second photocatalyst layer, and a second co-catalyst. This provides an artificial photosynthesis module with high reaction efficiency.

An artificial photosynthesis module includes an oxygen generation electrode having a first photocatalyst layer that decomposes water with light to generate oxygen, and has a first substrate, a first conductive layer, a first photocatalyst layer, and a first co-catalyst, and a hydrogen generation electrode that decomposes water with light to generate hydrogen and has a second substrate, a second conductive layer, a second photocatalyst layer, and a second co-catalyst. This provides an artificial photosynthesis module with high reaction efficiency.

An iron-free supported catalyst for the selective conversion of hydrocarbons to carbon nanotubes may include cobalt and vanadium as active catalytic metals in any oxidation state on a catalyst support comprising aluminum oxide hydroxide. The mass ratio of cobalt to vanadium is between 2 and 15; the mass ratio of cobalt to aluminum is between 5.8?10.sup.?2 and 5.8?10.sup.?1; and the mass ratio vanadium to aluminum is between 5.8?10.sup.?3 and 8.7?10.sup.?2. The present disclosure is further related to a method for the production of this iron-free supported catalyst and to a method for the production of carbon nanotubes using the iron-free supported catalyst.

Disclosed are a catalyst for oxidative dehydrogenation and a method of preparing the same. More particularly, a catalyst for oxidative dehydrogenation of butene having a high butene conversion rate and superior side reaction inhibition effect and thus having high reactivity and high selectivity for a product by preparing metal oxide nanoparticles and then fixing the prepared metal oxide nanoparticles to a support, and a method of preparing the same are provided.

A selective catalytic reduction catalyst composition for converting oxides of nitrogen (NO.sub.x) in an exhaust gas using a nitrogenous reductant comprises a mixture of a first component and a second component, wherein the first component is an admixture of the H-form of an aluminosilicate mordenite zeolite (MOR) and an iron-promoted aluminosilicate MFI zeolite; and the second component is a vanadium oxide supported on a metal oxide support, which is titania, silica-stabilized titania or a mixture of both titania and silica-stabilized titania, wherein the weight ratio of the first component to the second component is 10:90 to 25:75.

The present disclosure discloses a supported polymetallic oxide tandem catalyst, preparation method and application thereof, a surface of the support is supported with an oxide of metal A and then with metal vanadate nano-particles; and the oxide of metal A serves as a direct dehydrogenation catalytic site, and the metal vanadate nano-particles serve as a selective hydrogen combustion site. In the application of the tandem catalyst, dehydrogenation site and selective hydrogen combustion site are coupled at the nano-scale, and this coupling mechanism shifts the reaction equilibrium to the alkenes through the selective combustion of byproduct hydrogen, which effectively surpasses the thermodynamic limit; and meanwhile, the combustion of hydrogen releases chemical energy, and provides heat energy through direct heating, enabling the self-heating operation of the reaction. The present disclosure has the outstanding advantages of high single-pass conversion rate of light alkanes and high selectivity towards target product alkenes.

A catalyst comprising a barium niobate-based perovskite structure where, Mg and Ca has been used to dope the niobium sites along with one or more of Fe, Ni, Co, Y, Yb, W, Ta, and Pr.

Disclosed herein are new mixed metal oxide catalysts suitable as heterogeneous catalysts for catalyzing the transesterification process of aromatic alcohols with a dialkyl carbonate to form aromatic carbonates. The heterogeneous catalyst comprises a combination of two, three, four, or more oxides of Mo, V, Nb, Ce, Cu, Sn, or an element selected from Group IA or Group IIA of the periodic table.