Syngas to isoparaffins: Rationalizing selectivity over zeolites assisted by a predictive isomerization model

Direct synthesis of branched alkanes (isoparaffins) from syngas via Fischer-Tropsch synthesis (FTS) remains a challenge and hence has attracted much attention. Although progress has been made in exploiting some solid acids as catalyst to improve selectivity, a wide scope of uncertainty still exists in determining the major influential factors. Therefore, in this work, we investigate and presented the effects of zeolite characteristics such as the acidity, pore properties, and mass ratio on the selective production of isoparaffins in FTS. Co/SiO2 catalyst was coupled with the zeolites, Beta, ZSM-5, and SAPO-11 for this investigation. The results indicated that large pore acidic zeolites have the propensity to produce more multi-branched alkanes since they allow molecule proximity to facilitate isomerization. Also, strong acid sites tend to over-crack long-chain hydrocarbons to short-chains. The results of this study provide a rationale path capable of guiding the design of catalysts for optimized isoparaffin synthesis, directly from syngas.

Automated summary

This study investigated the effects of different acidic zeolites on the selective production of isoparaffins in Fischer-Tropsch synthesis. It was found that large-pore acidic zeolites tend to produce more multi-branched alkanes, while strong acid sites lead to over-cracking of long-chain hydrocarbons into short-chain hydrocarbons. The results provide insights for designing catalysts optimized for isoparaffin synthesis directly from syngas.