Insights into the promotional roles of palladium in structure and performance of cobalt-based zeolite capsule catalyst for direct synthesis of C5–C11 iso-paraffins from syngas

Abstract

Pd-promoted zeolite capsule catalyst (Co/Pd/SiO 2-HZSM5) was developed by coating H-ZSM-5 zeolite shell over Pd-modified core catalyst (Co/Pd/SiO 2), and employed for direct synthesis of C 5-C 11 iso-paraffins from syngas via Fischer-Tropsch synthesis (FTS). The roles of Pd promotion in structure and performance of the capsule catalyst for C 5-C 11 iso-paraffins synthesis were deeply studied. Structure characterizations (XRD, FTIR, TPR, and XPS) indicated that the main cobalt species in Pd-promoted capsule catalyst was cobalt silicate, while Co 3 O 4 was the predominant cobalt species in un-promoted capsule catalyst (Co/SiO 2-HZSM5).

Influence of Co Precursor and Pt Additive on Catalytic Performance of Highly Active Co/SiO₂-based Fischer-Tropsch Synthesis Catalysts

“…However, fine Co particles were hard to be reduced since these particles interacted with catalyst support strongly. One effective methodology to boost up the reduction degree of these fine cobalt oxide particles was implanting the co-existing noble metals such as Pt, Pd, to facilitate the H2 spillover by these co-existing noble metals from syngas, quickly reducing the neighboring cobalt oxide species 5) .…”

Design and Synthesis of Powerful Capsule Catalysts Aimed at Applications in C1 Chemistry and Biomass Conversion

“…Furthermore, Pd and other noble metals, such as Pt and Ru, when supported on or mixed with acidic zeolites, can enhance the hydrogenation and isomerization of hydrocarbons and thus increase the selectivity to isoparaffins. Based on the consideration, we introduced the Pd metal in the zeolite capsule FTS catalyst and investigated its promotion effect …”

“…Dry sputtering is an ideal method to prepare the catalyst with weak interaction between Pd and zeolite surface, but this process is more suitable for laboratory scale catalyst preparation and is difficult to use on a large scale at present. We have developed an alternative method for the preparation of Pd‐promoted capsule catalysts by first introducing Pd into the core catalysts (such as Co/SiO 2 ) and then synthesizing the zeolite shell of the capsule catalyst . The effect of Pd on the catalyst structure and performance for C 5 ‐C 11 isoparaffins synthesis was systematically studied.…”

Effect of proximity and support material on deactivation of bifunctional catalysts for the conversion of synthesis gas to olefins and aromatics

“…[12,13] The supplemento fa nH -ZSM-5 zeolite facilitatesc racking of the C 12 + fraction to hydrocarbonsi nt he gasoline range (C 5 -C 12 )w ith at otal carbon selectivityo fc lose to 60 %. [14][15][16] Combining an unpromoted iron-based FTS catalyst forming olefins with az eolite enables the formation of aromatics to a certain degree [17,18] relatedt ot he higher reactivity of olefins compared with paraffins and the variability in reaction temperature of iron catalysts. [19][20][21] According to the hydrogen transfer mechanism, three paraffin molecules are produced from olefins for every aromatic molecule that is formed.…”

“…Atomicr atio of hydrogen and carbon in the hydrocarbon products (C 1 -C16 )and selectivity towards olefins, paraffins,a nd aromatics as af unction of zeolite/FTO catalyst ratio at 400 8C, CO/H 2 = 1, GHSV:7 200 h À1 ,t otal pressure:1bar,and after4hons tream with CO conversion levels of 1.2 AE 0.1 %. The lower hydrogen/carbonr atio at zeolite/FTO of two indicates dehydrogenation.T he selectivity towards aromatics stayedc onstanti ndependent of the amountofz eolite added, whereas olefins were hydrogenatedt of orm paraffins with increasing amountsofz eolite present.…”