Here in, we are reporting the effect of the catalyst particle size on the catalytic activity and product selectivity by understanding the strength of the interaction between the active catalyst and the reactants (CO2 and H2). In this regard, two catalytic systems having different active catalyst particle sizes and support surface areas were synthesized using metal-organic frameworks (MOF) (MIL-100(Fe)) having two crystal size ranges as sacrificial templates. The active catalyst having smaller nanoparticles exhibited greater chemisorption of hydrogen (Fe-H bond), resulting in heightened selectivity for paraffin due to hydrogenation of re-adsorbed olefins. Conversely, larger nanoparticles showed enhanced chemisorption of CO2 (Fe-C bond), leading to increased selectivity for olefins (O/P = 0.15). Additionally, a reduction in particle size boosts activity from 24% to 38.7% at 340 °C/20 bar. While, higher particle size enhances the selectivity towards C5+ from 11.1 to 45.6% at (300 °C/10 bar) and 9.6 to 21.3% at (340 °C/20 bar).
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