Citation: Portillo, A.; Parra, O.; Aguayo, A.T.; Ereña, J.; Bilbao, J.; Ateka, A. Setting up In 2 O 3 -ZrO 2 / SAPO-34 Catalyst for Improving Olefin Production via Hydrogenation of CO 2 /CO Mixtures. Catalysts 2023, 13, 1101. https://doi.org/10.3390/ catal13071101 Academic Editor: Zhong-Wen Liu Received: 2 June 2023 Revised: 11 July 2023 Accepted: 12 July 2023 Published: 14 July 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). catalysts Article Setting up In 2 O 3 -ZrO 2 /SAPO-34 Catalyst for Improving Olefin Production via Hydrogenation of CO 2 /CO Mixtures Ander Portillo * , Onintze Parra , Andrés T. Aguayo, Javier Ereña , Javier Bilbao and Ainara Ateka * Department of Chemical Engineering, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain * Correspondence: ander.portillo@ehu.eus (A.P.); ainara.ateka@ehu.eus (A.A.); Tel.: +34-94-6015341 (A.A.) Abstract: The adequate configuration and the effect of the reduction was studied for the In 2 O 3 - ZrO 2 /SAPO-34 catalyst with the aim of improving its performance (activity and selectivity in the pseudo-steady state) for the hydrogenation of CO, CO 2 and CO 2 /CO (CO x ) mixtures into olefins. The experiments were carried out in a packed bed reactor at 400 ◦ C; 30 bar; a H 2 /CO x ratio of 3; CO 2 /CO x ratios of 0, 0.5 and 1; a space time (referred to as In 2 O 3 -ZrO 2 catalyst mass) of 3.35 g InZr h mol C −1 ; and a time on stream up to 24 h. The mixture of individual catalyst particles, with an SAPO-34 to In 2 O 3 -ZrO 2 mass ratio of 1/2, led to a better performance than hybrid catalysts prepared via pelletizing and better than the arrangement of individual catalysts in a dual bed. The deactivation of the catalyst using coke deposition and the remnant activity in the pseudo-steady state of the catalyst were dependent on the CO 2 content in the feed since the synergy of the capabilities of the SAPO-34 catalyst to form coke and of the In 2 O 3 -ZrO 2 catalyst to hydrogenate its precursors were affected. The partial reduction of the In 2 O 3 -ZrO 2 /SAPO-34 catalyst (corresponding to a superficial In 0 /In 2 O 3 ratio of 0.04) improved its performance over the untreated and fully reduced catalyst in the hydrogenation of CO to olefins, but barely affected CO 2 /CO mixtures’ hydrogenation. Keywords: CO 2 ; In 2 O 3 catalyst; SAPO-34 catalyst; methanol synthesis; olefin synthesis; coke deactivation 1. Introduction The production of light olefins from biomass gasification-derived syngas and CO 2 receives great attention to achieve the objective of net-zero carbon emissions by 2050 [1], and their industrial implementation is conditioned to the availability of green H 2 obtained from renewable energy [2]. The increasing demand of light olefins due to their use as key building blocks in the chemical industry justifies this initiative [3], replacing the technologies of the steam cracking of oil fractions [4], fluidized catalytic cracking (FCC) [5] and the conversion of methanol (MTO process) [6], which lead to large CO 2 emissions. The direct conversion of CO, CO 2 and CO 2 /CO mixtures into olefins can proceed via two different routes with tandem catalysts. In the modified Fischer–Tropsch (MFT) route, an acid zeolite is added to the FT catalyst (based on Fe or Co) for the selective conversion into olefins of the higher-hydrocarbon product of the FT synthesis (with char- acteristic Anderson–Schulz–Flory (ASF) distribution) [7,8]. The route with oxygenates (methanol/DME) as intermediates proceeds over oxide/zeotype (OX/ZEO) tandem cat- alysts, composed of a metallic oxide for the synthesis of oxygenates and a zeotype for their conversion into olefins. The attractiveness of these direct olefin synthesis routes lies in the lower infrastructure requirement compared with the two-stage processes and in the reduction of the thermodynamic limitations of the intermediates’ (methanol/DME) formation. This advantage is a consequence of the shift in the equilibrium of their formation (Equations (1)–(3)) due to their in situ conversion, mainly into olefins (Equation (4)). CO + 2 H 2 ⇋ CH 3 OH (1) Catalysts 2023, 13, 1101. https://doi.org/10.3390/catal13071101 https://www.mdpi.com/journal/catalysts