More than 95% (in volume) of all today's chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic research field. In this regard, Metal Organic Frameworks (MOFs) offer great opportunities for the rational design of new catalytic solids, as highlighted by the unprecedented number of publications appearing over the last decade. In this review, the recent advances in the application of MOFs in heterogeneous catalysis are discussed. MOFs with intrinsic thermo-catalytic activity, as hosts for the incorporation of metal nanoparticles, as precursors for the manufacture of composite catalysts and those active in photo and electrocatalytic processes are critically reviewed. The review is wrapped up with our personal view on future research directions.
We report the synthesis of a highly active and stable metal‐organic framework derived Ni‐based catalyst for the photothermal reduction of CO2 to CH4. Through the controlled pyrolysis of MOF‐74 (Ni), the nature of the carbonaceous species and therefore photothermal performance can be tuned. CH4 production rates of 488 mmol g−1 h−1 under UV‐visible‐IR irradiation are achieved when the catalyst is prepared under optimized conditions. No particle aggregation or significant loss of activity were observed after ten consecutive reaction cycles or more than 12 hours under continuous flow configuration. Finally, as a proof‐of‐concept, we performed an outdoor experiment under ambient solar irradiation, demonstrating the potential of our catalyst to reduce CO2 to CH4 using only solar energy.
Dry reforming of methane (DRM) involves the conversion of CO2 and CH4, the most important greenhouse gases, into syngas, a stoichiometric mixture of H2 and CO that can be further processed via Fischer–Tropsch chemistry into a wide variety of products. However, the devolvement of the coke resistant catalyst, especially at high pressures, is still hampering commercial applications. One of the relatively new approaches for the synthesis of metal nanoparticle based catalysts comprises the use of metal-organic frameworks (MOFs) as catalyst precursors. In this work we have explored MOF-74/CPO-27 MOFs as precursors for the synthesis of Ni, Co and bimetallic Ni-Co metal nanoparticles. Our results show that the bimetallic system produced through pyrolysis of a Ni-Co@CMOF-74 precursor displays the best activity at moderate pressures, with stable performance during at least 10 h at 700 °C, 5 bar and 33 L·h−1·g−1.
The direct hydrogenation of CO 2 to higher alcohols has the potential to turn the main contributor of global warming into a valuable feedstock. However, for this technology to become attractive, more efficient and, especially, selective catalysts are required. Here we present a high throughput study on the influence of different promoters on the CO 2 hydrogenation performance of RhÀ SiO 2 catalysts. Fe and K promoters were found to improve ethanol selectivity at the expense of undesired CH 4 . The best-performing catalyst, with a composition 2 wt.% K, 20 wt.% Fe, and 5 wt.% Rh, displays an EtOH selectivity of 16 % at CO 2 conversion level of 18.4 % and CH 4 selectivity of 46 %. The combination of different characterization techniques and catalyst screening allowed us to unravel the role of each catalyst component in this complex reaction mechanism.
The use of metal−organic frameworks (MOFs) as precursors for the manufacture of heterogeneous catalysts has gained a great deal of attention over the last decade. By subjecting a given MOF to pyrolysis, electrochemical degradation, or other treatments under a controlled atmosphere, (supported) metal (oxide) nanoparticles with very narrow size distributions can be obtained, opening the door to the design of more efficient catalytic solids. Here, we demonstrate the benefits of steam during the controlled decomposition of two different MOF structures (Basolite F300(Fe) and In@ZIF-67(Co)) and the consequences of treatment under this mildly oxidizing atmosphere on the properties of the resulting catalysts for the direct hydrogenation of CO 2 to hydrocarbons and methanol. In-depth characterization demonstrates that steam addition helps to control the phase composition both before and after catalysis; additionally, it results in the formation of smaller nanoparticles, thus leading to more efficient catalysts in comparison with conventional pyrolysis.
The direct utilization of light to drive chemical reactions has been considered a promising approach to decarbonizing the chemical industry and storing solar energy in the form of chemical bonds. In this regard, photo-thermal catalysis has emerged as a bright strategy due to the combination of thermal and non-thermal contributions of sunlight. This enables the whole exploitation of the solar spectrum providing localized heating and thus an enhancement in the productivity rates. In this scenario, MOFs and MOFs-derived materials offer great opportunities for the rational design of new photo-thermal catalysts. In this review, we describe the different types of photo-thermal systems, with a particular consideration on the mechanisms. Further, we describe the recent advances of MOF and MOF-derived materials as photo-thermal catalysts for different catalytic reactions, including organic transformations, pollutant degradation or CO 2 hydrogenations. Lastly, we present our opinion on the future challenges and perspectives in the field.
Photo-thermal catalysis has recently emerged as a viable strategy to produce solar fuels or chemicals using sunlight. In particular, nanostructures featuring localized surface plasmon resonance (LSPR) hold great promise as photo-thermal catalysts given their ability to convert light into heat. In this regard, traditional plasmonic materials include gold (Au) or silver (Ag), but in the last years, transition metal nitrides have been proposed as a cost-efficient alternative. Herein, we demonstrate that titanium nitride (TiN) tubes derived from the nitridation of TiO2 precursor display excellent light absorption properties thanks to their intense LSPR band in the visible–IR regions. Upon deposition of Ru nanoparticles (NPs), Ru-TiN tubes exhibit high activity towards the photo-thermal CO2 reduction reaction, achieving remarkable methane (CH4) production rates up to 1200 mmol g−1 h−1. Mechanistic studies suggest that the reaction pathway is dominated by thermal effects thanks to the effective light-to-heat conversion of Ru-TiN tubes. This work will serve as a basis for future research on new plasmonic structures for photo-thermal applications in catalysis.
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