Influence of Impregnation and Ion Exchange Sequence on Metal Localization, Acidity and Catalytic Performance of Cobalt BEA Zeolite Catalysts in Fischer‐Tropsch Synthesis

Abstract

Cobalt distribution between the external surface and micropores and acidity of the large pore BEA zeolite were controlled by choosing the sequence of impregnation and ion exchange procedures. Higher concentration of ion exchangeable cobalt was observed in the catalyst prepared by ion‐exchange of the zeolite proton form. The presence of Na+ instead of H+ ions in the exchange positions of zeolite favored deposition of cobalt on the external surface. The acid sites in the zeolite micropores can be then restored by subsequent ion exchange of sodium with ammonium nitrate and calcination. The catalytic performance of the cobalt zeolite catalysts prepared using different impregnation and ion exchange procedures was tested in the Fischer‐Tropsch synthesis. Higher reaction rates were observed over the catalysts, which did not contain cobalt ions in the cation sites of the zeolite. Lower methane selectivity, higher selectivity to long chain hydrocarbons and high fraction of isomerized products are observed when cobalt species are located on the zeolite outer surface and acid sites inside the BEA zeolite micropores.

Brief Study of Metal-substituted ZSM-5 -Potential Application in Methanol Production

“…NH3-TPD profiles of ZSM-5(30), Cu/ZSM-5(30), and Fe/ZSM-5 were synthesized using the SSIE method (Kalamaras et al, 2016) Impregnation method Another method that can be used in zeolite modification with the addition of metal is the impregnation technique. Impregnation techniques are classified into two, namely Incipient Wetness Impregnation (IWI) and Wet Impregnation (WI) (Flores et al, 2019). Incipient Wetness Impregnation (IWI) technique or also called dry impregnation involves capillary filling of the pores of the catalyst supported by metal with the addition of a minimum of solvent.…”

Zeolite-Containing Co Catalysts for Fischer–Tropsch Synthesis with Tailor-Made Molecular-Weight Distribution of Hydrocarbons

“…In [85], cobalt distribution between the external surface and micropores of the large pore HBeta zeolite were controlled by choosing the sequence of impregnation and ion exchange method. In this connection, the strength and number of Bronsted and Lewis active sites were changed.…”

Rational Positioning of Metal Ions to Stabilize Open Tin Sites in Beta Zeolite for Catalytic Conversion of Sugars

“…Such incorporation can affect the local connectivity and the stability of the framework Sn. [6,18] Indeed, the enhancement of Sn-Beta catalytic efficiency by metal ions was reported. Tolborg et al [13] increased methyl lactate (MLA) yield to more than 65 % by adding alkali metal salts during the hydrothermal synthesis of Sn-Beta with sucrose as feedstock.…”