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In this contribution we propose an alternative catalytic system based on MOF derivatives and small pore zeolites for the selective conversion of CO 2 into light olefins, using the lowest metal loadings and highest GHSV reported in literature. The catalyst synthesis involves deriving InÀ Zr oxides from MOFs containing these metals in their structure, i. e. (Zr)UiO-67-bipy-In, via direct calcination in the presence of the zeolite, avoiding co-precipitation, washing and mixing steps. This effectively creates a truly bifunctional InÀ Zr zeolite catalyst, opposed to physical mixtures of two catalysts using different precursors. The good dispersion and low loadings of the MOF-derived InÀ Zr oxide supplemented with the strong acidity of chabazitetype zeolites allows to couple the activation of CO 2 with CÀ C coupling, obtaining space time yields of 0.1 mol of CO 2 converted to light olefins per gram of In per hour at 375°C, under the GHSV conditions employed.

The conditions for promoting the joint conversion of CO2 and syngas in the direct synthesis of light olefins have been studied. In addition, given the relevance for the viability of the process, the stability of the In2O3–ZrO2/SAPO-34 (InZr/S34) catalyst has also been pursued. The CO+CO2 (CO x ) hydrogenation experimental runs were conducted in a packed bed isothermal reactor under the following conditions: 375–425 °C; 20–40 bar; space time, 1.25–20 gcatalyst h molC –1; H2/(CO x ) ratio in the feed, 1–3; CO2/(CO x ) ratio in the feed, 0.5; time on stream (TOS), up to 24 h. Analyzing the reaction indices (CO2 and CO x conversions, yield and selectivity of olefins and paraffins, and stability), the following have been established as suitable conditions: 400 °C, 30 bar, 5–10 gcat h molC –1, CO2/CO x = 0.5, and H2/CO x = 3. Under these conditions, the catalyst is stable (after an initial period of deactivation by coke), and olefin yield and selectivity surpass 4 and 70%, respectively, with light paraffins as byproducts. Produced olefin yields follow propylene > ethylene > butenes. The conditions of the process (low pressure and low H2/CO x ratio) may facilitate the integration of sustainable H2 production with PEM electrolyzers and the covalorization of CO2 and syngas obtained from biomass.

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