title: The effect of Mg location on Co-Mg-Ru/γ-Al2O3 Fischer-Tropsch catalysts.
abstract: The effectiveness of Mg as a promoter of Co-Ru/γ-Al2O3 Fischer-Tropsch catalysts depends on how and when the Mg is added. When the Mg is impregnated into the support before the Co and Ru addition, some Mg is incorporated into the support in the form of MgxAl2O3+x if the material is calcined at 550°C or 800°C after the impregnation, while the remainder is present as amorphous MgO/MgCO3 phases. After subsequent Co-Ru impregnation MgxCo3-xO4 is formed which decomposes on reduction, leading to Co(0) particles intimately mixed with Mg, as shown by high-resolution transmission electron microscopy. The process of impregnating Co into an Mg-modified support results in dissolution of the amorphous Mg, and it is this Mg which is then incorporated into MgxCo3-xO4. Acid washing or higher temperature calcination after Mg impregnation can remove most of this amorphous Mg, resulting in lower values of x in MgxCo3-xO4. Catalytic testing of these materials reveals that Mg incorporation into the Co oxide phase is severely detrimental to the site-time yield, while Mg incorporation into the support may provide some enhancement of activity at high temperature.
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK m.j.rosseinsky@liverpool.ac.uk.
authors.forename: James R
authors.identifier: http://orcid.org/0000-0002-5628-5178
authors.initials: JR
authors.lastname: Gallagher
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
authors.forename: Paul
authors.identifier: http://orcid.org/0000-0003-0058-6876
authors.initials: P
authors.lastname: Boldrin
authors.affiliation: Johnson Matthey PLC, PO Box 1, Belasis Avenue, Billingham TS23 1LB, UK.
authors.forename: Gary B
authors.initials: GB
authors.lastname: Combes
authors.affiliation: Johnson Matthey PLC, Blount's Court, Sonning Common, Reading RG4 9NH, UK.
authors.forename: Don
authors.initials: D
authors.lastname: Ozkaya
authors.affiliation: Johnson Matthey PLC, Blount's Court, Sonning Common, Reading RG4 9NH, UK.
authors.forename: Dan I
authors.initials: DI
authors.lastname: Enache
authors.affiliation: Johnson Matthey PLC, Blount's Court, Sonning Common, Reading RG4 9NH, UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ellis
authors.affiliation: Johnson Matthey PLC, PO Box 1, Belasis Avenue, Billingham TS23 1LB, UK.
authors.forename: Gordon
authors.initials: G
authors.lastname: Kelly
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
authors.forename: John B
authors.identifier: http://orcid.org/0000-0003-4849-6714
authors.initials: JB
authors.lastname: Claridge
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rosseinsky
keywords: Fischer–Tropsch; XRD; alumina; catalysis; cobalt