The invention discloses a catalyst used for preparing
methane by using a synthesis gas and a preparation method thereof. The catalyst has the characteristics of high
thermal stability, high catalytic activity, high
methane space time yield and the like. The preparation method is characterized in that: in a preparation process of the catalyst,
urea or NH4CO3 is heated to decompose so as to generate
ammonia and CO2; on one hand, the
ammonia and an
active ingredient nickel salt of the catalyst form a complex compound; and on the other hand, the production of a large amount of gas aggravates the dispersion of particles, so that a porous surface is formed easily and catalyst activity is enhanced. Due to the addition of a proper amount of alkali metals such as Mg, Na and the like and
rare earth elements such as La and the like, the
thermal stability and the anti-carbon property of the catalyst can be improved. A finished product catalyst comprises the following components in percentage by
mass: 75 to 85 percent of Al2O3, 15 to 25 percent of NiO, 1 to 5 percent of MgO, 0.5 to 3 percent of La2O3, and 0.2 to 1 percent of Na2O; the specific surface of the catalyst is 223 m<2> / g; and the pore volume is 0.16 to 0.20 cm<2> / g.