In this paper

H/CO/N was employed as the feed gas mixture and ZSM-5 zeolite served as a support. Through the impregnation method

two varieties of catalysts

Ni/ZSM-5 and Ni-Mg/ZSM-5

were synthesized. By means of characterization techniques including BET

H-TPR

H-TPD

TEM

XRD

TG

in conjunction with the CO methanation experiments

the impacts of temperature （300-700 ℃）

Ni loading （5%

10%

15%）

and Mg promoter on the catalytic performance were investigated. The outcomes manifest that subsequent to the addition of the additive Mg into the Ni/ZSM-5 catalyst

the quantity of its surface active sites augmented remarkably

the particle size of Ni diminished conspicuously

the dispersibility was substantially ameliorated

the anti-coking property was fortified

the amount of carbon deposition was curtailed by around 0.354%

and the maximum CH yield was elevated by 6.7%. When the temperature was set at 650 ℃

the 15%Ni-Mg/ZSM-5 catalyst demonstrated the most outstanding methanation performance. Under such circumstances

its CO conversion

CH selectivity and CH yield were 79.2%

75.5%

and 59.8%

respectively. Additionally

based on in situ infrared spectroscopy characterization and density functional theory calculations

formate was identified as an intermediate in the CO methanation pathway. The complete reaction pathway proceeds as follows：CO+H→CO+2H→HCOO→HCOOH→HCOOH →HCO→HCOH→CH→CH→CH→CH.