Mesoporous Beta Zeolite-Supported Ruthenium Nanoparticles for Selective Conversion of Synthesis Gas to C₅–C₁₁Isoparaffins

Abstract

Mesoporous beta (meso-beta) zeolites prepared by post-treatment of H-beta with NaOH aqueous solution were studied as supports of Ru catalysts for Fischer–Tropsch (FT) synthesis. The size and volume of the mesopores increased with the concentration of NaOH. The Brønsted acidity declined because Na+ ions were exchanged into the meso-beta during the post-treatment, and a further ion exchange of the meso-beta with NH4 + followed by calcination, forming H-meso-beta, could recover the Brønsted acidity. The use of H-meso-beta or meso-beta instead of H-beta or Na-beta as the support for FT synthesis decreased the selectivities to CH4 and heavier hydrocarbons (C12 +) and increased that to C5–C11 hydrocarbons. The C5–C11 selectivity depended on the concentration of NaOH used for meso-beta preparation. Under an optimum NaOH concentration, a C5–C11 selectivity of 77%, significantly higher than the maximum expected from Anderson–Schulz–Flory distribution (∼45%), was attained with a ratio of isoparaffins to n-paraffins being 2.7. The mesoporosity and the unique acidity of the meso-beta probably contribute to the selective hydrocracking of the primary heavier hydrocarbons formed on Ru nanoparticles into gasoline-range liquid fuels.

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

“…Such favorable formation for the high-octane value gasoline was attributed to the mesoporous structure and the unique acidity of hierarchical MFI zeolite. In addition to the MFI structure, hierarchical BEA zeolite was also tested for FT conversion after supporting Ru metal nanoparticles [144]. Similar to the result obtained over Ru/MFI system, the Ru/BEA zeolite could also produce gasoline-range liquid fuels with high-octane value.…”

“…H 2 ) to hydrocarbon is at the center of the gas-to-liquid (GTL) processes, which is very powerful catalytic process for production of liquid fuel sources such as gasoline and diesel from syngas [139][140][141]. Various hierarchical zeolites supporting various metal nanoparticles such as Co, Ru and Fe have been recently investigated for FT conversion [142][143][144]. Co metal nanoparticles were supported on pure-silica delaminated ITQ-2 and ITQ-6 zeolites, among which the Co/ITQ-6 showed the highest activity about 1.5 and 1.8 times higher than that of Co/MCM-41 and Co/SiO2, respectively (Table 3) [142].…”

Fischer–Tropsch Catalysts for the Production of Hydrocarbon Fuels with High Selectivity

“…[83,84] Characterization by argon adsorption and TEM clarified that the hierarchical ZSM-5 and beta zeolites prepared by this technique contained both micropores with a size of about 0.55 or 0.67 nm, which is typical for ZSM-5 or beta, and mesopores with sizes ranging from about 3 to 12 nm. [83,84] Characterization by argon adsorption and TEM clarified that the hierarchical ZSM-5 and beta zeolites prepared by this technique contained both micropores with a size of about 0.55 or 0.67 nm, which is typical for ZSM-5 or beta, and mesopores with sizes ranging from about 3 to 12 nm.…”

Filter and buffer-pot confinement effect of hollow sphere catalyst for promoted activity and enhanced selectivity

“…The C 5 -C 11 selectivity of 45.8% was quite close to the maximum value theoretical value predicted by the ASF law. 32 Contrastively, the hollow catalysts, especially the optimized CA/HS-2p one, exhibited a narrower product distribution, mainly concentrated at the C 5 -C 11 hydrocarbons with decreased CH 4 selectivity, and increased amount of olens and iso-paraffins. The gasolinerange component selectivity of 60.6% obviously breaks the ASF law and strikingly exceeds the value of the conventional solid catalyst.…”