Factors influencing activity/selectivity of La-promoted MgO catalyst prepared from La- and Mg- acetates for oxidative coupling of methane
✍ Scribed by V.R Choudhary; V.H Rane; S.T Chaudhari
- Book ID
- 104135512
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 187 KB
- Volume
- 79
- Category
- Article
- ISSN
- 0016-2361
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✦ Synopsis
In¯uence of La/Mg ratio (0.0±1.0), catalyst calcination temperature (600±12008C), gas atmosphere used in the catalyst calcination (viz. static air, ¯owing air, ¯owing moist air, ¯owing N 2 or ¯owing CO 2 ) on the activity and selectivity of La-promoted MgO, prepared from mixed La-and Mg-acetates by calcination in the oxidative coupling of methane both at lower (600±7008C) and higher (750±8508C) temperatures and low contact time (space velocity: 51,360 cm 3 g 21 h 21 ) has been investigated. In¯uence of these parameters on the strong basicity (measured in terms of CO 2 chemisorbed at 5008C) and surface area of the catalyst has also been studied. The parameters have a strong in¯uence on both the basicity and surface area; the basicity is passed through a maximum and the surface area is decreased continuously with increasing La/Mg ratio or catalyst calcination temperature. However, the parameters have strong in¯uence on the activity and selectivity of the catalyst only at the lower reaction temperatures (#7008C); their in¯uence is decreased gradually with increasing temperature, indicating a change in the controlling mechanism from heterogeneous to homogeneous reaction. The catalysts with La/Mg ratio of 0.005±0.25 show a good activity/selectivity in the OCM process at low temperatures (600±7008C).