The separation of ethylene (C2H4) from ethane (C2H6) is a critical yet energy-intensive process in the chemical industry, demanding energy-efficient and cost-effective solutions. Here, we report a Li+-exchanged silicoaluminophosphate RHO zeolite (Li-SAPO-RHO) with unprecedented selectivity for C2H4 over C2H6. This exceptional performance is attributed to the synergy between H+ and Li+ ions strategically positioned at the flexible eight-membered ring (8MR) gates of the zeolite. These ions effectively modulate the transport barriers for C2H4 and C2H6, significantly enhancing separation efficiency. Li-SAPO-RHO exhibits an Ideal Adsorbed Solution Theory selectivity exceeding 20,000 and enables the production of polymer-grade C2H4 (>99.9%) from refinery dry gas, with a productivity of up to 238.6 mmol/L. This performance surpasses that of all existing zeolite and metal-organic framework-based benchmark adsorbents. The H+-Li+ synergistic gating effect has been investigated using advanced characterization techniques, such as electron diffraction and neutron powder diffraction, along with ab initio molecular dynamics simulations. In addition to its exceptional selectivity and productivity, Li-SAPO-RHO offers advantages of low-cost synthesis, ultrahigh stability, and excellent cyclic performance, making it a highly promising candidate for industrial-scale light olefin separations.

Selective oxidation of methane to methanol under mild conditions remains a long-standing challenge because of the high inertness of the C-H bond in methane and the susceptibility of methanol to overoxidation. Here, we report a nitrogen-incorporation strategy for constructing TiO2-supported Au catalysts with cationic Au sites for selective methane oxidation using O2 as the oxidant in aqueous CH4/O2/CO media. The optimized Au/N-TiO2 catalyst delivers a methanol productivity of 3956 mu mol gcat -1 h-1, corresponding to 177 mol molAu -1 h-1, with 98% selectivity at 180 degrees C, demonstrating superior catalytic performance to most reported systems under comparable conditions. Spectroscopic and structural analyses reveal that nitrogen incorporation modulates the electronic state of Au and, in combination with an appropriate Au particle size, establishes a favorable size-charge match for constructing highly efficient interfacial active sites. Isotope-labeling experiments, in situ DRIFTS, kinetic analysis, and density functional theory calculations show that the reaction proceeds through a CO-assisted, surface-mediated O2 activation pathway involving surface methoxy species as key intermediates.

Flooding is an increasingly important driver of water quality degradation and human exposure to industrial contaminants under changing climate conditions. Floodwaters mobilize contaminants stored in sediments, soils, industrial facilities, and aging infrastructure, altering transport pathways, geochemical behavior, and exposure risks across aquatic and terrestrial environments. This review synthesizes current understanding of flood-induced contaminant mobilization in the United States and evaluates implications for water quality, human health, and environmental policy. A structured, evidence-informed review of peer-reviewed literature and governmental reports published between 1990 and 2026 was conducted, integrating findings across hydrodynamic forcing, sediment transport, geochemical transformation, infrastructure failure, and human exposure pathways. The analysis indicates that floods mobilize contaminants through multiple interacting mechanisms, including sediment resuspension, erosion of contaminated soils, geochemical transformations, and releases from damaged infrastructure. Distinct transport behaviors were identified among contaminant classes, with metals and persistent organic pollutants transported predominantly through sediment-associated pathways, while more mobile compounds such as per- and polyfluoroalkyl substances (PFAS) are often transported in dissolved phases. Organic industrial chemicals exhibit mixed dissolved and particulate transport pathways, while flood-induced changes in redox conditions, salinity, and organic matter availability strongly influence contaminant mobility, persistence, and bioavailability. Human exposure occurs through contaminated drinking water, direct floodwater contact, aerosol inhalation, contaminated soils and sediments, and food-chain transfer. The magnitude and persistence of contamination vary substantially with flood characteristics, sediment properties, contaminant type, and geochemical conditions. Although consistent evidence supports the importance of sediment-associated transport and infrastructure-mediated releases, significant uncertainties remain regarding post-flood remobilization, contaminant mixtures, and long-term health risks. These findings highlight the need for improved event-based monitoring, integrated modeling frameworks, and risk-informed policy strategies to better manage water quality and protect public health in increasingly flood-prone environments.”

The selective hydrogenation of 1,3-butadiene to 1-butene represents a pivotal process in the purification of industrial olefin streams, yet its performance is often hindered by undesired 1-butene isomerization to 2-butene. Herein, we employ parahydrogen-induced polarization (PHIP) nuclear magnetic resonance (NMR) spectroscopy as a pathway-sensitive probe to unravel the mechanistic origin of this isomerization. Pd-Au alloy nanoparticles supported on TiO2 with systematically tuned Pd/Au mass fractions reveal a distinct mechanistic transition governing 1-butene reactivity. Combined PHIP NMR, CO diffuse reflectance infrared Fourier transform spectroscopy (CO-DRIFTS), and quasi-in situ X-ray photoelectron spectroscopy (XPS) analyses demonstrate that on contiguous Pd ensembles, 1-butene isomerization is primarily driven by hydrogen surface coverage. Progressive incorporation of Au into the alloy disrupts these Pd ensembles, generating isolated Pd sites that shift the reaction control toward a competitive adsorption regime, wherein preferential 1,3-butadiene adsorption effectively suppresses 1-butene isomerization. Under reaction conditions, carbonaceous restructuring further stabilizes the single-atom Pd species, reinforcing the inhibition of isomerization.

The selective oxidation of methane to methanol and acetic acid represents a promising strategy for valorizing abundant natural gas into valuable chemicals. Using zeolite (ZSM-5)-supported Au nanoparticles from colloidal adsorption, deposition precipitation and wet impregnation methods, we demonstrate the selective oxidation of methane by cofeeding CH4, CO, O2 and steam in a high-pressure continuous flow reactor. Oxygenates (methanol, acetic acid and other trace chemicals.) and higher hydrocarbons (ethane) were produced in addition to carbon dioxide. The catalyst synthesis protocols showed a strong influence on the catalytic performance. Infrared spectroscopy and electron microscopy studies suggest that Au nanoparticles rather than ionic Au species are responsible for the active sites in the selective oxidation of methane.

Understanding the distinct roles of Brønsted and Lewis acid sites remains a great challenge in designing zeolite catalysts, as their coexistence often obscures mechanistic understanding. Here, we combine solid-state NMR spectroscopy with density functional theory to elucidate the site-specific pathways of ethanol dehydration to ethylene over ZSM-5 zeolite. Two key intermediates are identified: chemisorbed ethanol on Lewis acid sites (LAS) and surface ethoxy species on Brønsted acid sites (BAS), both formed via -OH activation followed by β-H elimination to yield ethylene. Comparative analysis reveals a thermodynamic-kinetic trade-off between the two sites. LAS facilitates low-temperature -OH activation but exhibits high barriers for β-H elimination, limiting ethylene formation. In contrast, BAS requires higher activation energy for -OH activation but enables more facile β-H elimination, promoting ethylene production. This intrinsic trade-off, governed by the thermodynamics of -OH activation, provides a mechanistic basis for understanding and tuning alcohol dehydration on zeolite acid sites.

Coupled NH3 and CO2 upcycling represents a promising strategy for the treatment of NH3- and CO2-containing gas streams. Photocatalysis delivering high-potential redox charges enables NH3 oxidation to N2 and CO2 reduction to CO, yet competing pathways and active-site interference usually limit overall performance. Here, we develop a tandem photocatalytic system comprising two spatially separated barium tetratitanate-based modules for NH3 oxidation coupled with CO2 reduction. The Ag or RhCrOx sites on the photocatalysts complementarily regulate competitive CO and H2 formation and, crucially, do not promote and instead partially suppress the generation of reactive oxygen species responsible for NH3 overoxidation, while hole-driven NH3 deprotonation promotes proton-coupled electron transfer for the progression of H2-evolution and CO2-reduction intermediates. By harnessing reaction-specific contributions of Ag- and RhCrOx-modified photocatalyst modules, the tandem system accomplishes effective gas-phase NH3 removal with ≥92% NH3 conversion to near-exclusive N2 and sustains stable CO/H2 production, outperforming most temperature- and concentration-dependent thermocatalytic and photocatalytic NH3 oxidation to N2 processes. The reaction integration and catalyst system design provide a process-intensified and resource-efficient route toward the unified control of pollutant- and CO2-containing gas streams.

Zeolites are crystalline,microporous solids characterized by periodic networks of uniform,molecular-sized channels and cavities.The first natural zeolite,stilbite,was discovered in 1756,while the systematic synthesis of zeolitic materials began in the 1940s.Their frameworks possess well-defined,sub-nanometer micropores(＜2 nm),which provide a confined environment ideal for selective adsorption,diffusion,and ion exchange.This functionality underpins their critical role as industrial adsorbents and detergent co-builders.Additionally,the ability to precisely tune chemical composition,acidity,and active site distribution positions zeolites as essential heterogeneous catalysts in modern petrochemical processing.

Selective oxidation of methane to methanol under mild conditions remains a long-standing challenge because of the high inertness of the C-H bond in methane and the susceptibility of methanol to overoxidation. Here, we report a nitrogen-incorporation strategy for constructing TiO2-supported Au catalysts with cationic Au sites for selective methane oxidation using O2 as the oxidant in aqueous CH4/O2/CO media. The optimized Au/N-TiO2 catalyst delivers a methanol productivity of 3956 μmol gcat-1 h-1, corresponding to 177 mol molAu-1 h-1, with 98% selectivity at 180 °C, demonstrating superior catalytic performance to most reported systems under comparable conditions. Spectroscopic and structural analyses reveal that nitrogen incorporation modulates the electronic state of Au and, in combination with an appropriate Au particle size, establishes a favorable size-charge match for constructing highly efficient interfacial active sites. Isotope-labeling experiments, in situ DRIFTS, kinetic analysis, and density functional theory calculations show that the reaction proceeds through a CO-assisted, surface-mediated O2 activation pathway involving surface methoxy species as key intermediates.

The synergistic interplay between Br & oslash;nsted and Lewis acid sites in zeolites plays a key role in biomass conversion, yet direct assessment of such site cooperation remains challenging. Here, advanced two-dimensional solid-state NMR spectroscopy combined with probe-molecule analysis is employed to directly identify and semiquantitatively quantify proximate Br & oslash;nsted/Lewis acid site pairs in Sn-Al-beta zeolites for glucose conversion. By tuning the Sn/Al ratio, the abundance of framework Sn-derived Lewis acid sites is varied while maintaining comparable Br & oslash;nsted acidity, enabling the effect of acid-site proximity to be disentangled. H-1-P-31 and P-31-P-31 correlation NMR experiments reveal the spatial proximity between Br & oslash;nsted acid sites and framework Sn-derived Lewis acid sites and show that neighboring Lewis acid sites are associated with enhanced Bro/nsted acidity. The estimated concentration of BAS-LAS pairs correlates strongly with the apparent initial methyl levulinate formation rate, whereas the total BAS or LAS concentrations alone do not capture the same trend.

Abstract Identifying metal anchoring sites and their role in dynamic evolution is an important fundamental problem for catalysis research. For industrially used Al2O3 supports, precisely identifying metal anchoring sites remains challenging due to the intricate, diverse nature of their surface structures. Here, we deposited Pt nanoparticles onto hydroxyl groups (–OH) and lattice oxygen sites on hydroxyl-rich and partially dehydrated alumina. Different from the prevailing report of AlV consumption, AlVI transforms to AlV during Pt deposition on lattice oxygen sites. Moreover, different anchoring sites alter catalytic performance by driving the structural evolution of Pt atoms during hydrogenation. Pt nanoparticles bonded to hydroxyl groups are stable, while those nucleated on lattice oxygen undergo atomic redistribution to form more active sites for aromatic hydrogenation. These insights establish a direct link between initial coordination environment and dynamic behavior, advancing molecular-level understanding of metal–support interactions.

Herein, to overcome the practical challenges of photocatalytic CO2 reduction, NH2-MIL-125 (NM) and alkali metal ion-dopant photocatalysts (X-NM, X = Li, Na, K) were synthesized via a solvothermal method. Their structure and morphology are characterized by XRD, SEM and EDS, confirming them retained crystal structure of NM. Under a pure CO2 atmosphere, Na-NM achieved 133.17 mu mol g- 1 CO production after 4 h illumination, which is 1.4 times that of NM and exhibited 98.1% selectivity for CO. Under a dilute CO2 (20%) atmosphere or an aerobic CO2 atmosphere (80% CO2 and 20% O2), Na-NM demonstrates superior performance compared to pristine NM. Density Functional Theory (DFT) reveal Na+ increase the CO2 adsorption energy while decreasing that of O2. This work provides a feasible solution for the application of photocatalytic CO2 reduction in aerobic CO2 atmosphere.

The concept of metal-ligand bifunctional catalysts has been extensively explored in homogeneous catalysis, yet it has not been reported in conventional heterogeneous catalysis. Inspired by the outer-sphere hydrogenation mechanism in homogeneous metal-ligand bifunctional catalysts, we here find that an Ir single-atom catalyst with a predominantly Ir1-P4 coordination structure behaves as a heterogeneous metal-ligand bifunctional catalyst exclusively favoring the hydrogenation of the C═O bond over the C═C bond in α,β-unsaturated aldehydes─an industrially important but highly challenging transformation. The hydrogenation process is revealed to proceed through a Noyori-type transition state during the 1,2-addition pathway at the Ir-P bifunctional sites, as evidenced by combining the in situ two-dimensional 1H-1H spin diffusion and 1H-31P heteronuclear correlation nuclear magnetic resonance spectroscopy, apparent reaction order test, kinetic isotope effect analysis, and density functional theory calculations. This work demonstrates a new type of heterogeneous metal-ligand bifunctional catalyst for the chemoselective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols and sheds light on the hydrogenation mechanism.

Ethylene/ethane separation underpins global polyolefin production but remains one of the most energy-intensive processes in the chemical industry because it relies on cryogenic distillation. Adsorptive separation using porous materials offers a promising alternative to conventional cryogenic distillation, potentially reducing energy consumption. However, the nearly identical physical properties of ethylene and ethane make the development of highly selective adsorbents exceptionally challenging. Herein, we report a lithium-exchanged silicoaluminophosphate RHO zeolite (Li-SAPO-RHO) that achieves unprecedented ethylene/ethane separation by exploiting a cooperative gating mechanism in a flexible framework. A synergistic proton-Li+ gating effect at the flexible 8-ring apertures differentially modulates molecular transport barriers. Brønsted protons selectively facilitate ethylene diffusion, while Li+ cations create a trapdoor barrier that preferentially suppresses ethane transport, thereby amplifying kinetic discrimination. As a result, Li-SAPO-RHO exhibits excellent ethylene-selective adsorption performance, enabling the direct production of polymer-grade ethylene (>99.9%) from refinery dry gas with a productivity of 238.6 mmol/L. Structural analyses combined with ab initio molecular dynamics simulations reveal how proton-cation synergy amplifies kinetic discrimination between closely related molecules. These findings establish gate cooperativity as a powerful design principle for energy-efficient adsorptive separations. Due to its low cost, exceptional hydrothermal stability, and excellent cycling performance, Li-SAPO-RHO offers a promising platform for industrial light-olefin separations.

Amorphous silica-aluminas (ASAs) are widely used catalysts, with a distribution of Brønsted acid sites (BAS), that yield unique catalytic properties exploited in numerous industrial settings. While having atomic-level insight into their structures, in particular their interfacial sites, would be key to enable rational design, these sites are notoriously difficult to characterize due to spectral complexity arising from a diversity of hydroxyls and the overwhelming interference from noninterfacial signals. Herein, we introduce a 27Al-filtered 1H-1H double-quantum/single-quantum NMR (f-DQ/SQ) spectroscopy method integrated with DFT calculations to probe hydroxyls at solid-state interfaces selectively. Combined with probe molecule (acetone and TMP) adsorption experiments, this approach unequivocally demonstrates that hydrothermal post-treatment increases BAS density in ASA. Dynamic-nuclear-polarization-enhanced 29Si-{27Al} D/J-based correlation experiments corroborate the rearrangement process at the silica-alumina interface, while the heteronuclear-filtered 1H-1H DQ/SQ NMR reveals that the increase in BAS density originates from the formation of specific pseudobridged silanol (PBS) pairs─a distinction imperceptible in conventional 1H or 1H-{27Al} correlation NMR. PBS pairs constitute ca. 73% of the total PBS population, estimated by a semiquantitative analysis combining 27Al-filtered experiments and spin-dynamics simulations. Through a time-dependent 1H-1H f-DQ/SQ variant, we quantified key interatomic distances (∼2 Å for H-H and ∼4.1 Å for H-Al) within these PBS motifs. Constrained DFT calculations ultimately identify a vicinal-silanol-derived configuration as the most stable PBS structure, being 294 kJ/mol lower in relative energy, thereby resolving the atomic-scale origin of augmented acidity in hydrothermally treated ASAs.

The synergistic interplay between Brønsted and Lewis acid sites in zeolites plays a key role in biomass conversion, yet direct assessment of such site cooperation remains challenging. Here, advanced two-dimensional solid-state NMR spectroscopy combined with probe-molecule analysis is employed to directly identify and semiquantitatively quantify proximate Brønsted/Lewis acid site pairs in Sn-Al-β zeolites for glucose conversion. By tuning the Sn/Al ratio, the abundance of framework Sn-derived Lewis acid sites is varied while maintaining comparable Brønsted acidity, enabling the effect of acid-site proximity to be disentangled. 1H-31P and 31P-31P correlation NMR experiments reveal the spatial proximity between Brønsted acid sites and framework Sn-derived Lewis acid sites and show that neighboring Lewis acid sites are associated with enhanced Bro̷nsted acidity. The estimated concentration of BAS-LAS pairs correlates strongly with the apparent initial methyl levulinate formation rate, whereas the total BAS or LAS concentrations alone do not capture the same trend.

In situ solid-state nuclear magnetic resonance (NMR) serves as a powerful means to study catalytic reactions under operating conditions. Standard solid-state NMR rotors typically struggle to match the pressure and temperature of active reactions during sampling. Here, we introduce specialized inserts for commercial solid-state NMR rotors capable of withstanding pressures from atmospheric to 618.3 kPa and temperatures ranging from room temperature up to 433 K. With this innovative design, we examine the isomerization of dihydroxyacetone (DHA) on Sn-MFI zeolite catalyst using in situ 1H MAS NMR, revealing the presence of a gem-diols-type intermediate during the transformation of DHA into glyceraldehyde.