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1. Recent Advances in the Mitigation of the Catalyst Deactivation of CO2 Hydrogenation to Light Olefins

   https://doi.org/10.3390/catal11121447  

   Weber, Daniel; He, Tina; Wong, Matthew; Moon, Christian; Zhang, Axel; Foley, Nicole; Ramer, Nicholas J.; Zhang, Cheng (December 2021, Catalysts)

   The catalytic conversion of CO2 to value-added chemicals and fuels has been long regarded as a promising approach to the mitigation of CO2 emissions if green hydrogen is used. Light olefins, particularly ethylene and propylene, as building blocks for polymers and plastics, are currently produced primarily from CO2-generating fossil resources. The identification of highly efficient catalysts with selective pathways for light olefin production from CO2 is a high-reward goal, but it has serious technical challenges, such as low selectivity and catalyst deactivation. In this review, we first provide a brief summary of the two dominant reaction pathways (CO2-Fischer-Tropsch and MeOH-mediated pathways), mechanistic insights, and catalytic materials for CO2 hydrogenation to light olefins. Then, we list the main deactivation mechanisms caused by carbon deposition, water formation, phase transformation and metal sintering/agglomeration. Finally, we detail the recent progress on catalyst development for enhanced olefin yields and catalyst stability by the following catalyst functionalities: (1) the promoter effect, (2) the support effect, (3) the bifunctional composite catalyst effect, and (4) the structure effect. The main focus of this review is to provide a useful resource for researchers to correlate catalyst deactivation and the recent research effort on catalyst development for enhanced olefin yields and catalyst stability. 

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2. Strategies for Designing the Catalytic Environment Beyond the Active site of Heterogeneous Supported Metal Catalysts

   https://doi.org/10.1007/s11244-023-01835-2  

   Bhat, Samiha; Pagán-Torres, Yomaira J.; Nikolla, Eranda (June 2023, Topics in Catalysis)

   Significant emphasis has been placed recently in engineering the catalytic environment beyond the active site for tuning the activity, selectivity, and stability of supported metal catalysts for targeted reactions. The environment around the active site in supported catalysts can be modified by introducing multi-dimensionality through alloying, encapsulation, and surface bound ligands. In this Review, we provide a summary of synthesis strategies that have enabled the design of multifunctionality and multidimensionality in heterogeneous supported catalysts. We specifically discuss alloys, encapsulated/inverted catalytic structures, and ligand capped metal nanoparticle systems. We highlight the effects on catalyst activity, selectivity and stability that arise from modifying the neighboring two-dimensional environment through alloying or three-dimensional environment through encapsulation with porous inorganic films or surface organic moieties. We conclude by providing a short perspective on the promises and remaining challenges associated with engineering the local environment around the active sites of supported heterogeneous catalysts. 

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3. Mechanistic insights into alkene chain growth reactions catalyzed by nickel active sites on ordered microporous and mesoporous supports

   https://doi.org/10.1039/d0cy01186j  

   Joshi, Ravi; Saxena, Arunima; Gounder, Rajamani (November 2020, Catalysis Science & Technology)

   null (Ed.)

   Alkene oligomerization on heterogeneous Ni-based catalysts has been studied for several decades, with recent attention focused on the preparation, structure and function of Ni active site motifs isolated within microporous and mesoporous supports, including zeolites and metal–organic frameworks (MOFs). This mini-review focuses on the active site requirements and the microscopic kinetic and mechanistic details that become manifested macroscopically as activation and deactivation behavior during oligomerization catalysis and that determine measured reaction rates and selectivity among alkene isomer products. The preponderance of mechanistic evidence is consistent with the coordination–insertion (Cossee–Arlman) cycle for alkene oligomerization prevailing on heterogeneous Ni-exchanged zeolites and MOFs, even when external co-catalysts are not present, as they often are in homogeneous Ni-based oligomerization catalysis. Certain mechanistic features of the coordination–insertion route allow catalyst and active site design strategies to influence product selectivity. Our mini-review provides a critical discussion of reported alkene oligomerization data and the challenges in their measurement and interpretation and concludes with an outlook for future research opportunities to improve our kinetic and mechanistic understanding of alkene chain growth chemistries mediated by Ni-based porous catalysts. 

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4. Support Effects on Fe- or Cu-Promoted Ni Catalysts Used in the Catalytic Deoxygenation of Tristearin to Fuel-like Hydrocarbons

   https://doi.org/10.3390/catal15050501  

   Umenweke, Great C; Pace, Robert; Récalt, Thomas; Heintz, Olivier; Caboche, Gilles; Santillan-Jimenez, Eduardo (May 2025, Catalysts)

   Previous studies have shown that fats, oils, and greases (FOG) can be deoxygenated to fuel-like hydrocarbons over inexpensive alumina-supported Ni catalysts promoted with Cu or Fe to afford excellent yields of renewable diesel (RD). In this study, supports other than alumina—namely, SiO2-Al2O3, Ce0.8Pr0.2O2, and ZrO2—were investigated to develop catalysts showing improved RD yields and resistance to coke-induced deactivation relative to Al2O3-supported catalysts. Results showed that catalysts supported on Ce0.8Pr0.2O2 and ZrO2 outperformed SiO2-Al2O3-supported formulations, with 20%Ni-5%Fe/ZrO2 affording a quantitative yield of diesel-like hydrocarbons. Notably, the abundance of weak acid sites varied considerably across the different supports, and a moderate concentration of these sites corresponded with the best results. Additionally, temperature-programmed reduction measurements revealed that Ni reduction is greatly dependent on both the identity of the promoter and catalyst support, which can also be invoked to explain catalyst performance since metallic Ni is identified as the likely active site for the deoxygenation reaction. It was also observed that Ce0.8Pr0.2O2 provides high oxygen storage capacity and oxygen mobility/accessibility, which also improves catalyst activity. 

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5. Recyclable Catalysts for Alkyne Functionalization

   https://doi.org/10.3390/molecules26123525  

   Trigoura, Leslie; Xing, Yalan; Chauhan, Bhanu P. (June 2021, Molecules)

   In this review, we present an assessment of recent advances in alkyne functionalization reactions, classified according to different classes of recyclable catalysts. In this work, we have incorporated and reviewed the activity and selectivity of recyclable catalytic systems such as polysiloxane-encapsulated novel metal nanoparticle-based catalysts, silica–copper-supported nanocatalysts, graphitic carbon-supported nanocatalysts, metal organic framework (MOF) catalysts, porous organic framework (POP) catalysts, bio-material-supported catalysts, and metal/solvent free recyclable catalysts. In addition, several alkyne functionalization reactions have been elucidated to demonstrate the success and efficiency of recyclable catalysts. In addition, this review also provides the fundamental knowledge required for utilization of green catalysts, which can combine the advantageous features of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis. 

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