Effects of Li and Al2O3 support on the improvement of light hydrocarbons selectivity in Ru-based Fischer–Tropsch reaction

• Published in: Reaction kinetics, mechanisms and catalysis Vol. 117; no. 1; pp. 129 - 146
• Main Authors: Murata, Kazuhisa, Takahara, Isao, Inaba, Megumu, Liu, Yanyong
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2016
• Subjects: Catalysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Physical Chemistry; Lithium; Light hydrocarbons; Ruthenium; Alumina support; Fischer–Tropsch synthesis
• ISSN: 1878-5190; 1878-5204
• DOI: 10.1007/s11144-015-0937-x

The catalytic activities directing for an improvement of light olefin (C2′–C4′) selectivity were investigated on the RuMnLi/Al 2 O 3 Fischer–Tropsch synthesis catalysts in a low pressure fixed-bed reactor. The C2′–C4′ selectivities of RuMnLi/α-Al 2 O 3 and RuMnLi/β-Al 2 O 3 were a little higher than that of RuMnLi/γ-Al 2 O 3 . The difference seems to stem mainly from the crystallite sizes of metallic ruthenium, which is in the order: RuMnLi/γ-Al 2 O 3  > RuMnLi/β-Al 2 O 3  > RuMnLi/α-Al 2 O 3 , as evaluated from XRD, CO chemisorption and NH 3 -TPD. The C3′ and 1-butene (1-C4′) were found to be predominantly formed over C2′ and, for C4, only n-butane and 1-C4′ were produced, but isobutane, isobutene and trans- or cis-2-butene were not formed, which is in sharp contrast with iron catalyst. Another reason for the improvement of C2′–C4′ selectivity is the Li effect, because, possibly, the secondary hydrogenation reaction of olefin intermediates could be suppressed on the Li-promoted catalyst. Thus, 50.2 % of C2′–C4′ selectivity was achieved at 300 °C and 0.5 MPa of CO/H 2 using RuMnLi/α-Al 2 O 3 .