A catalyst for methanation reaction and a method for preparing methane are provided. The catalyst for methanation reaction includes a core, a shell encapsulating the core, and an active metal. The core includes cerium dioxide (CeO.sub.2), the shell includes zirconium dioxide (ZrO.sub.2), and the active metal is in particle form and is disposed on an outer surface of the shell layer.

A composite catalyst containing heteroatom-doped zeolite for preparing light olefin using direct conversion of syngas is formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of component I is a metal oxide, and the component II is a heteroatom-doped zeolite. The zeolite topology is CHA or AEI, and the skeleton atoms include AlPO or SiAlPO; the heteroatoms is at least one of divalent metal Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Mo, Cd, Ba and Ce, trivalent metal Ti and Ga, and tetravalent metal Ge. A weight ratio of the active ingredient in the component I to the component II is 0.1-20. The reaction process has high light olefin selectivity; the sum selectivity of the light olefin including ethylene, propylene and butylene can reach 50-90%, while the selectivity of a methane side product is less than 7%.

A composite catalyst containing heteroatom-doped zeolite for preparing light olefin using direct conversion of syngas is formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of component I is a metal oxide, and the component II is a heteroatom-doped zeolite. The zeolite topology is CHA or AEI, and the skeleton atoms include AlPO or SiAlPO; the heteroatoms is at least one of divalent metal Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Mo, Cd, Ba and Ce, trivalent metal Ti and Ga, and tetravalent metal Ge. A weight ratio of the active ingredient in the component I to the component II is 0.1-20. The reaction process has high light olefin selectivity; the sum selectivity of the light olefin including ethylene, propylene and butylene can reach 50-90%, while the selectivity of a methane side product is less than 7%.

A catalyst comprising NiO, a metal mixture comprising at least one of MoO.sub.3 or WO.sub.3, a mixture comprising at least one of SiO.sub.2 and Al.sub.2O.sub.3, and P.sub.2O.sub.5. In this embodiment the metal sites on the catalyst are sulfided and the catalyst is capable of removing tar from a synthesis gas while performing methanation and water gas shift reactions at a temperature range from 300? C. to 600? C.

A catalyst comprising NiO, a metal mixture comprising at least one of MoO.sub.3 or WO.sub.3, a mixture comprising at least one of SiO.sub.2 and Al.sub.2O.sub.3, and P.sub.2O.sub.5. In this embodiment the metal sites on the catalyst are sulfided and the catalyst is capable of removing tar from a synthesis gas while performing methanation and water gas shift reactions at a temperature range from 300? C. to 600? C.

A process for preparing C.sub.2 to C.sub.4 hydrocarbons includes introducing a feed stream including hydrogen gas and a carbon-containing gas selected from the group consisting of carbon monoxide, carbon dioxide, and mixtures thereof into a reaction zone of a reactor, and converting the feed stream into a product stream including C.sub.2 to C.sub.4 hydrocarbons in the reaction zone in the presence of a formed hybrid catalyst. The formed hybrid catalyst includes a metal oxide catalyst component including gallium oxide and zirconia, a microporous catalyst component that is a molecular sieve having 8-MR (Membered Ring) pore openings, and a binder including alumina, zirconia, or both.

A process for preparing C.sub.2 to C.sub.4 hydrocarbons includes introducing a feed stream including hydrogen gas and a carbon-containing gas selected from the group consisting of carbon monoxide, carbon dioxide, and mixtures thereof into a reaction zone of a reactor, and converting the feed stream into a product stream including C.sub.2 to C.sub.4 hydrocarbons in the reaction zone in the presence of a formed hybrid catalyst. The formed hybrid catalyst includes a metal oxide catalyst component including gallium oxide and zirconia, a microporous catalyst component that is a molecular sieve having 8-MR (Membered Ring) pore openings, and a binder including alumina, zirconia, or both.

Synthesis of aromatic hydrocarbons from synthesis gas in a fixed bed or a moving bed reactor loaded with a composite catalyst comprising Catalyst Component A and Catalyst Component B mixed via a mechanical mixing mode, wherein the active ingredient of the Catalyst Component A is active metal oxides; and the Catalyst Component B is one or both of ZSM-5 zeolite and metal modified ZSM-5; the pressure of the synthesis gas is 0.1-6 MPa; the reaction temperature is 300-600 C.; and the space velocity is 500-8000 h.sup.1. The reaction process has a high product yield and selectivity, with the selectivity of aromatics reaching 50-85%, while the selectivity of the methane byproduct is less than 15%.

Synthesis of aromatic hydrocarbons from synthesis gas in a fixed bed or a moving bed reactor loaded with a composite catalyst comprising Catalyst Component A and Catalyst Component B mixed via a mechanical mixing mode, wherein the active ingredient of the Catalyst Component A is active metal oxides; and the Catalyst Component B is one or both of ZSM-5 zeolite and metal modified ZSM-5; the pressure of the synthesis gas is 0.1-6 MPa; the reaction temperature is 300-600 C.; and the space velocity is 500-8000 h.sup.1. The reaction process has a high product yield and selectivity, with the selectivity of aromatics reaching 50-85%, while the selectivity of the methane byproduct is less than 15%.

A process for preparing C2 and C3 olefins comprises contacting a feedstream including hydrogen, carbon monoxide, and a bifunctional catalyst in a reaction under certain specified conditions. The catalyst includes as components (1) chromium oxide and zinc oxide mixed metal oxides, and (2) a SAPO-34 molecular sieve. The resulting product of the reaction is relatively high in the target lower olefins and relatively low in less desirable products, including C2 and C3 paraffins, C4+ hydrocarbons, oxygenates, and methane, thereby reducing or eliminating the need for certain previously common and costly separations. The bifunctional catalyst as used in the inventive process also offers improvements in catalyst life in comparison with some methanol-to-olefins catalysts. The process may be carried out as a single unit operation.