Surface chemistry and catalytic activity of La/sub 1-y/M/sub y/CoO/sub 3/ perovskite (M = Sr or Th). II. Hydrogenation of CO/sub 2/

Journal Article · Fri May 01 00:00:00 EDT 1987 · J. Catal.; (United States)

OSTI ID:5329892

Ulla, M A; Migone, R A; Petunchi, J O; Lombardo, E A

The partial substitution of La/sup III/ by either Sr/sup II/ or Th/sup IV/ in lanthanum cobaltate perovskite affects both the rate of hydrogenation of carbon dioxide and the distribution of products. The active site density was calculated from the measured amount of chemisorbed hydrogen at 25/sup 0/C on the oxides reduced at temperatures between 250 and 500/sup 0/C. The catalytic activity was measured in a standard recirculation system using a H/sub 2/:CO/sub 2/ = 4:1 ratio, total pressure of 160 Torr, and 280/sup 0/C reaction temperature. The total conversion of CO/sub 2/ into products (activity) on LaCoO/sub 3/ is little affected by the extent of reduction of the sample. More sensitive to this parameter are both the rate of methanation and the production of C/sub 2//sup +/ compounds. Reduced La/sub 0.8/Th/sub 0.2/CoO/sub 3/ is very stable giving a constant activity, the highest of all the solids assayed and almost exclusively producing methane. La/sub 0.6/Sr/sub 0.4/CoO/sub 3/ shows a sharp maximum in activity and high selectivity to methane when prereduced at 300/sup 0/C. However, when reduced at increasing temperatures the overall activity sharply drops while the selectivity to higher hydrocarbons increases very rapidly. In runs designed to measure the extent of deactivation due to coke deposition it was found that the degree of activity decay was inversely correlated with the methanation selectivity. To gain further insight into both the matrix and promoter effect a series of catalysts were prepared containing different combinations of Co, Sr, La, and Th supported on either celite or La/sub 2/O/sub 3/. The matrix effect is most important in the Sr-substituted oxide, less so in LaCoO/sub 3/, and unimportant in the Th-containing perovskite. A model was proposed to interpret the effect of lanthanum replacement upon the catalytic activity, selectivity, and stability of these solids.

• Research Organization: Universidad Nacional del Litoral, Sante Fe, Argentina
• OSTI ID: 5329892
• Journal Information: J. Catal.; (United States), Vol. 105:1
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CARBON DIOXIDE
METHANATION
COBALT OXIDES
CATALYTIC EFFECTS
LANTHANUM
STRONTIUM
THORIUM
CATALYST SUPPORTS
CATALYSTS
CATALYTIC REFORMING
CHEMICAL REACTION KINETICS
CHEMISORPTION
COKE
DEACTIVATION
DEPOSITION
FISCHER-TROPSCH SYNTHESIS
HYDROGEN
HYDROGENATION
ISOMERIZATION
LANTHANUM OXIDES
MATHEMATICAL MODELS
METHANE
PEROVSKITES
PROMOTERS
REDUCTION
STABILITY
ACTINIDES
ALKALINE EARTH METALS
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT COMPOUNDS
ELEMENTS
HYDROCARBONS
KINETICS
LANTHANUM COMPOUNDS
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
RARE EARTHS
REACTION KINETICS
REFORMER PROCESSES
SEPARATION PROCESSES
SORPTION
TRANSITION ELEMENT COMPOUNDS
010408* - Coal
Lignite
& Peat- C1 Processes- (1987-)