Oxidative Dehydrogenation of Ethane with CO2 as a Soft Oxidant over a PtCe Bimetallic Catalyst

Pt2Gd Alloy Nanoparticles from Organometallic Pt and Gd Complexes and Hollow Mesoporous Carbon Spheres: Enhanced Oxygen Reduction Reaction Activity and Durability

Pt2Gd alloy nanoparticles supported in hollow mesoporous carbon spheres (HMCS; Pt2Gd/HMCS) were successfully prepared by the thermal reduction of organometallic Pt and Gd complexes without oxygen atoms supported in the pores of HMCS. The structures of Pt2Gd alloy nanoparticles were fully characterized by TEM, HAADF-STEM-EDS, XRD, XAFS, and XPS, suggesting the formation of uniform Pt2Gd alloy nanoparticles with an average particle size of 5.9 nm. Pt2Gd/HMCS showed superior oxygen reduction reaction activity (2.4 times higher mass-specific activity to Pt nanoparticles on HMCS (Pt/HMCS)) and remarkable durability even after the 100,000 cycles of accelerated degradation tests compared to Pt/HMCS and a commercial Pt/C catalyst. The structure of the Pt2Gd alloy nanoparticles after initial aging and the durability tests suggested that the Pt2Gd core-Pt shell structure with a particle size similar to the pore size of HMCS was stably formed inside the porous structure of HMCS and maintained under the oxygen-reduction working conditions.

Conversion of toxic pyrogenic products into syngas through catalytic pyrolysis of insulation material waste under the presence of CO2

Plastic-based insulation materials have been widely employed owing to their exceptional durability, cost-effectiveness, low weight, and low thermal conductivity. Nevertheless, the disposal of the insulation material waste (IMW) within construction waste and its recycling and recovery are challenging. Meanwhile, landfilling or incineration methods can release toxic chemicals into the environment. Consequently, the accumulation of IMW in construction waste has become a pressing environmental concern. To address this issue, this paper proposes a pyrolysis platform as a disposal management method for IMW that employs CO2 as a reactive medium. IMW composed of polystyrene in the form of extruded polystyrene underwent pyrolysis to yield pyrogenic products containing toxic chemicals. These toxic chemicals were subsequently transformed into syngas via homogeneous reactions with CO2 under certain thermal conditions and Ni/Al2O3 catalyst. This resulted in a significant reduction in the total peak areas of toxic substances in the pyrogenic oil compared with that obtained using N2 as a medium. Furthermore, the efficacy of CO2 was demonstrated to increase with an increase in the atmospheric concentration. This study implied that catalytic pyrolysis under CO2 conditions is a potential platform for converting toxic chemicals from IMW into syngas through homogeneous reactions with CO2.

Ultrafine Pt Nanoparticles on Defective Tungsten Oxide for Photocatalytic Ethylene Synthesis

The selective conversion of ethane (C2H6) to ethylene (C2H4) under mild conditions is highly wanted, yet very challenging. Herein, it is demonstrated that a Pt/WO3-x catalyst, constructed by supporting ultrafine Pt nanoparticles on the surface of oxygen-deficient tungsten oxide (WO3-x) nanoplates, is efficient and reusable for photocatalytic C2H6 dehydrogenation to produce C2H4 with high selectivity. Specifically, under pure light irradiation, the optimized Pt/WO3-x photocatalyst exhibits C2H4 and H2 yield rates of 291.8 and 373.4 µmol g-1 h-1, respectively, coupled with a small formation of CO (85.2 µmol g-1 h-1) and CH4 (19.0 µmol g-1 h-1), corresponding to a high C2H4 selectivity of 84.9%. Experimental and theoretical studies reveal that the vacancy-rich WO3-x catalyst enables broad optical harvesting to generate charge carriers by light for working the redox reactions. Meanwhile, the Pt cocatalyst reinforces adsorption of C2H6, desorption of key reaction species, and separation and migration of light-induced charges to promote the dehydrogenation reaction with high productivity and selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculation expose the key intermediates formed on the Pt/WO3-x catalyst during the reaction, which permits the construction of the possible C2H6 dehydrogenation mechanism.

Reactive Carbon Capture: Cooperative and Bifunctional Adsorbent-Catalyst Materials and Process Integration for a New Carbon Economy

ConspectusTo say the least, releasing CO2 into the atmosphere is reaping undue environmental consequences given the ever-present increase in severe global weather events over the past five years. However, it can be argued that-at least in the confines of current technological capabilities-the atmospheric release of CO2 is somewhat unavoidable given that even shifting toward clean energy sources-such as solar, nuclear, wind, battery, or H2 power-incurs an initial carbon requirement by way of manufacturing the very production abilities through which "clean" energy is generated. Even years from now, experts agree that energy production will be diversified and-as the global population continues to drive the growth of global energy consumption-thermal power derived from carbon combustion is likely to remain one intrinsic energetic source, of which CO2 will always be a byproduct. In this context, it is the responsibility of the scientific community to devise improved pathways of carbon management such that (i) the consequences of combustion on the global environment are reduced and (ii) carbon fuels can be leveraged in a sustainable fashion.In this Account, we discuss a pivotal perspective shift on CO2 emissions derived from a considerable breakthrough in material science from our work on shape engineering of nanoporous adsorbents and catalysts. This account details the development of materials which no longer vilify CO2 emissions as a valueless combustion byproduct, instead providing a path for them to become a potential feedstock. In more specific terms, this work details the development of structured, cooperative "bifunctional" materials (BFMs) comprised of (i) a high-temperature adsorbent and (ii) a heterogeneous catalyst that enable single-bed CO2 capture and utilization in oxidative ethane dehydrogenation (ODHE), oxidative propane dehydrogenation (ODHP), and dry methane reforming (DMR) processes. This Account begins with the conceptual development of the BFMs in the powdered state, followed by detailing the first-ever reports of structuring the materials into facile honeycomb contactors by 3D printing. The Account then summarizes the impressive performance of the 3D-printed BFMs, specifically focusing on how their catalysts (metal oxides and perovskites) influence their reactive CO2 capture performances in ODHE, ODHP, and DMR processes. Such promise of CO2-as-fuel offers a glimpse into the future of a diversified energy economy, in which CO2/fuel looping can play an important role. A major factor in achieving this future is, of course, developing an appropriately active catalyst; an account of whose first breakthroughs in material science are detailed herein.

Synthesis of Pt-Rare Earth Metal Alloys and Their Applications

The alloying of platinum (Pt) with rare earth (RE) metals has emerged as a highly promising strategy for enhancing both the activity and stability of catalysts. Consequently, the development of methods for the controlled synthesis of Pt-RE alloys has received growing attention. This review comprehensively explores diverse synthesis methodologies for Pt-RE alloys, including physical metallurgy method, chemical reduction method, electrodeposition method, and dealloying method. Additionally, this review summaries the applications of Pt-RE alloys in various fields. By providing a critical analysis of existing literature and highlighting key challenges and future directions, this review aims to offer valuable insights and serve as a springboard for further advancements in the controlled synthesis and diverse applications of Pt-RE alloys.

Encapsulating Metal Nanoparticles into a Layered Zeolite Precursor with Surface Silanol Nests Enhances Sintering Resistance

Supported metal nanoparticles are used as heterogeneous catalysts but often deactivated due to sintering at high temperatures. Confining metal species into a porous matrix reduces sintering, yet supports rarely provide additional stabilization. Here, we used the silanol-rich layered zeolite IPC-1P to stabilize ultra-small Rh nanoparticles. By adjusting the IPC-1P interlayer space through swelling, we prepared various architectures, including microporous and disordered mesoporous. In situ scanning transmission electron microscopy confirmed that Rh nanoparticles are resistant to sintering at high temperature (750 °C, 6 hrs). Rh clusters strongly bind to surface silanol quadruplets at IPC-1P layers by hydrogen transfer to clusters, while high silanol density hinders their migration based on density functional theory calculations. Ultimately, combining swelling with long-chain surfactant and utilizing metal-silanol interactions resulted in a novel, catalytically active material-Rh@IPC_C22.

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

Light olefins are important feedstocks and platform molecules for the chemical industry. Their synthesis has been a research priority in both academia and industry. There are many different approaches to the synthesis of these compounds, which differ by the choice of raw materials, catalysts and reaction conditions. The goals of this review are to highlight the most recent trends in light olefin synthesis and to perform a comparative analysis of different synthetic routes using several quantitative characteristics: selectivity, productivity, severity of operating conditions, stability, technological maturity and sustainability. Traditionally, on an industrial scale, the cracking of oil fractions has been used to produce light olefins. Methanol-to-olefins, alkane direct or oxidative dehydrogenation technologies have great potential in the short term and have already reached scientific and technological maturities. Major progress should be made in the field of methanol-mediated CO and CO₂ direct hydrogenation to light olefins. The electrocatalytic reduction of CO₂ to light olefins is a very attractive process in the long run due to the low reaction temperature and possible use of sustainable electricity. The application of modern concepts such as electricity-driven process intensification, looping, CO₂ management and nanoscale catalyst design should lead in the near future to more environmentally friendly, energy efficient and selective large-scale technologies for light olefin synthesis.

High-entropy intermetallics on ceria as efficient catalysts for the oxidative dehydrogenation of propane using CO2

The oxidative dehydrogenation of propane using CO2 (CO2-ODP) is a promising technique for high-yield propylene production and CO2 utilization. The development of a highly efficient catalyst for CO2-ODP is of great interest and benefit to the chemical industry as well as net zero emissions. Here, we report a unique catalyst material and design concept based on high-entropy intermetallics for this challenging chemistry. A senary (PtCoNi)(SnInGa) catalyst supported on CeO2 with a PtSn intermetallic structure exhibits a considerably higher catalytic activity, C3H6 selectivity, long-term stability, and CO2 utilization efficiency at 600 °C than previously reported. Multi-metallization of the Pt and Sn sites by Co/Ni and In/Ga, respectively, greatly enhances propylene selectivity, CO2 activation ability, thermal stability, and regenerable ability. The results obtained in this study can promote carbon-neutralization of industrial processes for light alkane conversion.