Influence of Zr, Ce, and La on Co 3 O 4 catalyst for CO 2 methanation at low temperature

Abstract The Co 3 O 4 and Zr-, Ce-, and La-Co 3 O 4 catalysts were prepared, characterized, and applied to produce CH 4 from CO 2 catalytic hydrogenation in low temperature as 140–220 °C. The results indicated that the addition of Zr, Ce, or La to the Co 3 O 4 decreased the crystallite sizes of Co and the outer-shell electron density of Co 3 + , and increased the specific surface area, which would provide more active sites for the CO 2 methanation. Especially, the addition of Zr also changed the reducing state of Co 3 O 4 via an obvious change in the interaction between Co 3 O 4 and ZrO 2 . Furthermore, Zr doped into the Co 3 O 4 increased the basic intensity of the weak and medium basic sites, as well as the amount of Lewis acid sites, and Bronsted acid sites were also found on the Zr-Co 3 O 4 surface. The introduction of Zr, Ce, or La favored the production of CH 4 , and the Zr-Co 3 O 4 catalyst exhibited the highest CO 2 conversion (58.2%) and CH 4 selectivity (100%) at 200 °C, and 0.5 MPa with a gaseous hourly space velocity of 18,000 ml·g cat − 1 ·h − 1 , and the catalytic activity of CO 2 methanation for the Zr-, Ce-, and La-Co 3 O 4 exhibited more stable than Co 3 O 4 in a 20-h reaction.