Multifunctional Catalyst Combination for the Direct Conversion of CO₂ to Propane

The production of carbon-rich hydrocarbons via CO₂ valorization is essential for the transition to renewable, non-fossil-fuel-based energy sources. However, most of the recent works in the state of the art are devoted to the formation of olefins and aromatics, ignoring the rest of the hydrocarbon commodities that, like propane, are essential to our economy. Hence, in this work, we have developed a highly active and selective PdZn/ZrO₂+SAPO-34 multifunctional catalyst for the direct conversion of CO₂ to propane. Our multifunctional system displays a total selectivity to propane higher than 50% (with 20% CO, 6% C₁, 13% C₂, 10% C₄, and 1% C₅) and a CO₂ conversion close to 40% at 350 °C, 50 bar, and 1500 mL g^-1 h^-1. We attribute these results to the synergy between the intimately mixed PdZn/ZrO₂ and SAPO-34 components that shifts the overall reaction equilibrium, boosting CO₂ conversion and minimizing CO selectivity. Comparison to a PdZn/ZrO₂+ZSM-5 system showed that propane selectivity is further boosted by the topology of SAPO-34. The presence of Pd in the catalyst drives paraffin production via hydrogenation, with more than 99.9% of the products being saturated hydrocarbons, offering very important advantages for the purification of the products.