Accurate prediction of aluminum chemistry in complex, high-ionic-strength environments is required for efficient processing of nuclear waste stored at the Hanford Site in Washington State. In this work, equilibrium dissolution of the aluminum hydroxide gibbsite was measured in nuclear waste simulants containing sodium salts of hydroxide, nitrate, nitrite, and phosphate as a function of temperature. Simulant compositions were informed by correlation analysis of the Hanford Best Basis Inventory to define representative multicomponent alkaline matrices. Dissolution data were evaluated using a pseudo-first-order model as an empirical description of the approach to equilibrium, with Monte Carlo simulations used to assess uncertainty under the experimental design. At 20 degrees C, gibbsite solubility in sodium hydroxide solutions: (i) was insensitive to the addition of 0.04 mol/kg phosphate; (ii) increased slightly in the presence of sodium nitrate and nitrite; and (iii) increased further when phosphate was added in addition to sodium nitrate and nitrite. At 40 degrees C, gibbsite solubility increased across all electrolyte compositions relative to 20 degrees C, with phosphate addition producing a larger effect in mixed nitrate-nitrite systems than in sodium hydroxide alone. X-ray diffraction and Raman spectroscopy confirmed gibbsite as the solubility-controlling solid phase and aluminate as the dominant aqueous aluminum species, respectively, under all conditions examined. The solubility variations are consistent with electrolyte-dependent activity effects and solution structuring in concentrated alkaline media, rather than with changes in aluminum crystalline phase or aqueous speciation. These results provide experimentally constrained solubility benchmarks for representative waste chemistries and inform predictive modeling of aluminum behavior in alkaline nuclear waste.

Rare earth elements (REEs) are critical for advanced technologies, yet in hydrothermal aqueous solutions the molecular level details of their interaction with ligands that control their geochemical transport and deposition remain poorly understood. This study elucidates the coordination behavior of Yb(III) in sulfate-rich hydrothermal fluids using in situ extended X-ray absorption fine structure (EXAFS) spectroscopy and ab initio molecular dynamics (AIMD) simulations. By integrating multi-angle EXAFS with AIMD-derived constraints, we precisely resolve Yb(III) coordination structures and ligand interactions under hydrothermal conditions. At room temperature, Yb (III) is coordinated by five water molecules and two sulfate ligands (coordination number, CN = 8), forming a distorted square antiprism geometry. Increasing temperature induces progressive dehydration, reducing the hydration shell and favoring stronger sulfate complexation. At 200 Celsius, sulfate ligands reorganize around Yb(III), shifting its geometry to a capped dodecahedron (CN = 7). At 300 Celsius, sulfate binding dominates, leading to structural reorganization that parallels the onset of sulfate mineral precipitation, consistent with the retrograde solubility of REE sulfates. These findings provide direct molecular-scale evidence that sulfate acts as both a transport and deposition ligand, critically influencing REE mobility in geochemical environments. Our results can also help to refine thermodynamic models of REE speciation in high-temperature hydrothermal fluids and improve our understanding of REE ore formation processes in nature.

To demonstrate the potential for bismuth(III) (Bi)-based materials to sequester subsurface contaminants in situ, aqueous batch experiments were performed to determine how sediments impact the sequestration of technetium (Tc), uranium (U), chromium (Cr), and iodine(I) with bismuth subnitrate (BSN) and bismuth oxyhydroxide (BOH). Results of these experiments demonstrated that Bi-based materials have the potential to rapidly remove colocated contaminants over a range of geochemical conditions representative of the Hanford Site and in the presence of Hanford subsurface sediments. In aqueous batch experiments without sediment, the hydrolysis of both BSN and BOH resulted in a lowering of the pH (to as low as 2.4 with BSN or 5.9 with BOH). In the presence of sediment, the pH was buffered at similar to 7-8 for both systems (BOH and BSN). In the absence of sediment, BOH readily sequestered U(VI) from its 2.3 mg/L solution under challenging conditions of a high solution-to-solid material ratio of 1000 mL/g or even when the U(VI) concentration was increased to 150 mg/L at a solution-to-solid material ratio of 200 mL/g. Cr(VI) was likewise readily removed from the aqueous phase at a concentration of 0.05 mg/L. A greater quantity of BOH (i.e., at a solution-to-solid ratio of 100-200 mL/g) was required for complete removal of Tc(VII) and I(V); changes in solution chemistry suggest that this is due to competing reactions with other ions, including chloride (Cl-) and sulfate (SO4 2-). In the presence of sediment, removal of Tc(VII) and I(V) decreased by respectively 91% and 21% for BOH and 33% and 93% for BSN. The presence of sediment increased removal of U(VI) by BSN to nearly 100%, while only 17% of U was removed in the absence of sediment. This study demonstrates that Bi-based materials show promise as a remediation tool to remove multiple contaminants from contaminated sediments, with the removal efficiency dependent on the amount of Bi-based material present in the sediment.

Replacing alkaline for alkaline-earth metal hydroxide in the synthesis of siliceous SSZ-13 zeolite (Si/Al~10) yields SSZ-13 with novel, advantageous properties. Its NH4-form ion-exchanges higher amount of isolated divalent M(II) ions than the conventional one: this is the consequence of increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO4- motives to reside closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and X-ray absorption spectroscopy measurements, and show their utility for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more isolated cobalt(II) and thus, perform better as ambient-air NOx adsorbers. Notably, Co(II)/SSZ-13 with increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading Pd(II) into Co-SSZ-13(Sr) produces an active NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in the presence of Sr(OH)2 does not lose its PNA capacity after extremely harsh aging at 850 and 900 ⁰C (10 hours in 10% H2O/air flow) and loses only ~55% capacity after hydrothermal aging at 930 ⁰C. This can be extended to other divalent metals for catalytic applications, such as copper: we show that Cu/SSZ-13 catalyst can survive hydrothermal aging at 920 ⁰C without losing its catalytic properties, metal dispersion and crystalline structure. Thus, we provide a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications.

This study examines a wide range of hybrid ion exchange (IX) resins that simultaneously remove multiple contaminants from groundwater via anion exchange and an additional mechanism, such as chemical reduction or adsorption. Hybrid resins aim to overcome pump-and-treat operational limitations when using singlecontaminant selective IX resins. Performance of hybrid and weak base hybrid IX resins for removing contaminants, including uranium (U as uranyl carbonates UO2(CO3)x2-2x), technetium-99 (as TcO4- ), and hexavalent chromium (Cr(VI) as CrO42-), as well as incidental removal of iodine-129 (as IO3- ), is compared to the performance of strong base anion exchange resins used to treat these contaminants individually. Batch and column tests were performed using ultrapure water and/or a simulated groundwater solution representative of the U.S. Department of Energy's Hanford Site. Several strong base and hybrid candidate resins could remove TcO4- . The weak base hybrid resin SIR-700 in its sulfate form performed the best for both Cr(VI) and U removal, yet demonstrated poor TcO4- removal. Removal of IO3- by anion exchange resins is typically not efficient. In this study, few hybrid resins demonstrated improved IO3- uptake compared to their parent resins because it was outcompeted by other more abundant anions. While the SBG1-Ce resin removed the most IO3- from simulated Hanford groundwater in the presence of all four contaminants, the cerium hybrid resin SIR-110-MP-Ce removed both TcO4- and the secondmost IO3- of the resins evaluated in column tests. IO3- in the presence of the other contaminants and natural groundwater anions, like sulfate, is not competitive for removal by ion exchange. Removal of IO3- is proposed to occur via adsorption as an inner- or outer-sphere complex to the hybrid metal phase. Optimizing access to these phases and increasing hybrid metal loading are expected to improve incidental IO3- removal.

Bismuth (Bi) materials are advantageous for the subsurface remediation of contaminants due to its low toxicity and cost. Depending on the groundwater pH and ions present, bismuth materials undergo structural transformations, enabling interactions with aqueous contaminants at legacy nuclear sites. Here, the performance of bismuth oxyhydroxide (BOH) and bismuth subnitrate (BSN) was investigated with respect to the uptake of iodine-129 (iodate (IO3 -) or iodide (I-)), chromium (chromate (CrO4 2-)), uranium-238 (uranyl carbonate complexes, (UO2(CO3) x 2-2x ) like UO2(CO3)3 4-), and technetium-99 (pertechnetate, (TcO4 -)) in arid and semiarid regions (e.g., western United States), specifically conditions representative of the geochemistry in the Central Plateau (200 Area) of the U.S. Department of Energy Hanford Site. The influence of solution chemistry on the time-dependent structural transformation of Bi-based materials between crystalline clusters and layered arrangements was assessed in experiments for up to 150 days using synthetic Hanford water. Aqueous environments, especially carbonate (CO3 2-), increase rates of Bi-based material structural transformation. Depending on solution pH and [CO3 2-], BOH, initially a disordered delta-Bi2O3-like phase (dis-BiOw(OH) x (NO3) y (CO3) z ), transforms to a layered bismutite (lay-Bi2O2(CO3)) with high affinities for IO3 -, CrO4 2-, and (UO2(CO3) x 2-2x ) complexes. The hydrolysis of BSN causes the pH to decrease from 7.98 to 3.38 such that an "unknown" phase with the general formula unk-Bi(NO3) x (OH) y O z , charge-balanced by nitrate (NO3 -) is formed and has a high affinity for TcO4 -. Overall, increasing concentrations of common groundwater anions result in smaller sized mineralogical transformation products with higher surface areas for contaminant sorption. The results corroborate that Bi-based materials are promising candidates for groundwater remediation at the Hanford Site.

The direct dissolution of voloxidized used nuclear fuel (UNF) into an organic solution-comprised of diluent and specialized extractants-poses a promising alternative to the traditional liquid-liquid solvent extraction approach to reprocessing UNF. However, moving to direct dissolution removes the presence of a concentrated nitric acid aqueous phase, which has been shown to significantly influence the radiolytic longevity of extractants in conventional extraction flowsheets. Given the limited knowledge of radiation effects under direct dissolution conditions, here we present a time-resolved and dose-accumulation study on the impact of direct dissolution conditions on the radiolytic longevity of two candidate butyramide extractants, N,N-di(2-ethylhexyl) butyramide (DEHBA) and N,N-di(2-ethylhexyl)isobutyramide (DEHiBA), in pre-equilibrated n-dodecane solvent in the presence and absence of process-relevant metal ions, specifically, uranium and rhenium. Loss G(DEHBA) and G(DEHiBA) values were found to be comparable to each other, with an average of 0.37 ± 0.02 μmol J-1, and to previous data from the γ irradiation of DEHBA and DEHiBA under conventional solvent extraction conditions. Rhenium, and by extension technetium, extraction had a modest decrease (∼10%) in the overall radiolytic stability of DEHiBA only, despite >2× observed increases in chemical kinetic reactivity of the corresponding complexes with the n-dodecane radical cation. Uranium loading, on the other hand, significantly improved the lifetime of both ligands (>30%) under γ irradiation, with a greater stabilization observed for DEHBA over DEHiBA. The observed radioprotective effect afforded by uranium loading is fortuitous for the longevity of direct dissolution solvent.

With the growing demand for stable and reliable grids, all-soluble iron (Fe) redox flow batteries offer a low-cost energy storage solution by using Fe and addressing corrosion and hydrogen evolution issues. We present the first approach using a non-nitrogenous bisphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP; etidronic acid), as a ligand to synthesize an Fe complex for a soluble aqueous Fe anolyte. This new Fe complex exhibits a significantly shifted negative redox potential compared to nitrogenous phosphonate analogs, resulting in a >30% increase in battery output voltage. Paired with a ferrocyanide (Fe(CN)(6)(4-)) catholyte, the system demonstrates stable cycling with no significant capacity degradation over 900 cycles and Coulombic and voltage efficiencies of 100% and 90%, respectively, at 20 mA/cm(2) and near-neutral pH (similar to 8). Various electrochemical tests, attenuated total reflectance (ATR), and X-ray absorption spectroscopies suggest the presence of bimetallic complexes as active redox species in the anolyte.

The direct extraction of uranium from voloxidized nuclear fuel into an organic solvent offers several potential advantages over conventional hydrometallurgical reprocessing, including reducing the reprocessing plant footprint, providing an initial degree of decontamination from fission products, and minimizing the amount of secondary waste from nitric acid. In this work, the direct extraction of uranium oxides into 1.5 M N,N-di(2-ethylhexyl)isobutyramide (DEHiBA) in n-dodecane is examined. UV-vis spectra and distribution ratios of HNO2 in 1.5 M DEHiBA as well as the equilibrium organic phase H2O concentrations in HNO3-loaded 1.5 M DEHiBA are also reported. Hypothesized reaction stoichiometries for the direct extraction of uranium from UO2, α-U3O8, and ε-UO3 are verified through analysis of organic-phase U, HNO2, and HNO3 concentrations after dissolution. Water generated by the dissolution results in the formation of a separate aqueous phase, which will need to be accounted for in future flowsheet design.

Successful deployment of in situ subsurface remediation strategies requires knowledge of contaminant geochemistry, and the impact of physicochemical sediment properties on remedy performance. Bismuth (Bi) materials can sequester multiple contaminants that are present in the unsaturated zone and groundwater at Department of Energy (DOE) legacy nuclear sites, such as the Hanford Site. Adsorption experiments for individual contaminants (chromate, iodate, pertechnetate, and uranyl carbonate) were conducted with two Bi materials: commercially available Bi-subnitrate (BSN); and laboratory synthesized Bi oxyhydroxide nitrate (BOH). The structure and composition of the Bi material influenced hydrolysis and ion exchange interactions in aqueous solution, with subsequent impacts on solution pH, contaminant speciation, and contaminant uptake. X-ray diffraction revealed that the disordered BOH structure, initially containing charge balancing nitrate and hydroxide anions, rapidly converted to bismutite, Bi2O2(CO3), in the presence of carbonate. During this transformation, BOH removed most contaminant ions from solution. [Bi6O5(OH)3]5+ clusters in BSN underwent hydrolysis upon exposure to aqueous solutions, substantially reducing pH, and transforming into several mineral phases, including a daubreeite (BiO(OH,Cl)) structure, and an unidentified mineral phase (unk-Bi(NO3)x(OH)yOz). This transformation decreased uptake efficiency relative to BOH, except for pertechnetate. The adsorption isotherms for the contaminants were fit with a Freundlich model that describes adsorption to Bi materials with dissimilar binding sites. Solid phase characterization after reaction confirmed structural rearrangement of the Bi materials and direct association of the contaminant ions with Bi mineral structures via different mechanisms, including anion exchange or outer-sphere complexation for pertechnetate, and inner-sphere adsorption for all other contaminants. Uranyl carbonate could substitute between the [Bi2O2]2+ layers, and some iodate was incorporated into a neo-formed delta-Bi2O3 phase. This remarkable versatility of Bi-based materials demonstrated here means that they are cost-effective materials with the potential to sequester co-located contaminants at DOE legacy sites.

Using ab initio based molecular dynamics and electronic structure calculations, we show that Zn impurities in hydrated amorphous calcium carbonate (ACC) have a much lower coordination number than other divalent impurities due to covalent interactions between the 3d Zn shell and the oxygen atoms of the carbonate and water groups. The local structure around Zn in ACC, including the predicted low coordination number, is confirmed by X-ray absorption spectroscopy of synthetic Zn-bearing ACC. The strong Zn-O chemical interaction leads to substantial water dissociation and slightly disrupts the hydrogen bonding network. Implications of Zn2+ incorporation for ACC stability are discussed.

Anchoring divalent metal ions in the same zeolite framework with similar Si/Al ratio selectively as zeolite‐bound M +2 or [M +2 ‐OH] +1 cationic species enables critical comparison of the species’ intrinsic reactivity for industrially and fundamentally relevant reactions. H‐BEA zeolites with similar Si/Al ratios but differing framework Al siting were used to anchored multiple divalent metal cations (Ni, Pd, Pt, Cr, Cu) in the zeolite micropores. State‐of‐the‐art infrared (IR) spectroscopy, electron paramagnetic resonance (EPR) measurements, including two‐dimensional pulsed HYSCORE EPR, extended X‐ray absorption fine structure (EXAFS), and density functional theory (DFT) calculations together provide unambiguous evidence for the selective formation of divalent metal cations as M +2 /2Al species (for H‐BEA prepared in the conventional hydroxide media), and [M +2 OH] +1 /1Al species for H‐BEA prepared in HF. Solid‐state proton‐decoupled triple‐quantum magic‐angle spinning (3Q MAS) NMR measurements confirmed contrasting Al distributions in the two H‐BEA zeolites, which led to a contrasting divalent cation speciation. The reactivities of the two cationic species were explored for catalytic and adsorptive applications in both organometallic homogeneous and heterogeneous catalysis. This work demonstrates their divergent reactivity in ethylene dimerization, ethylene oxidation (Wacker process), selective catalytic reduction (SCR) of NO, NO adsorption, and methane oxidation. Both M +2 /2Al and [M +2 OH] +1 /1Al cations are both active for ethylene dimerization, but [M +2 OH] +1 /1Al species show higher reaction rates for each Pd, Ni, Pt. [M +2 OH] +1 /1Al is active for acetaldehyde formation in Wacker ethylene oxidation. A new active site for ethylene oligomerization is proposed that possesses a terminal OH group (Cr‐OH) in Phillips catalysts evident by a nearly inactive isolated Cr +2 /2Al species that contrast an active Cr─OH motif.

Nitrilotriacetamides are an emerging class of extractants that have been identified as promising candidates for a variety of separation schemes. Systems incorporating these ligands are prone to third-phase formation at high loading, but this can be mitigated by increasing the alkyl chain length or adding a phase modifier (e.g., 1-octanol). In this work, the impacts of these modifications on HNO3 extraction, H2O extraction, and physicochemical properties (interfacial tension, viscosity, and density) are examined. The studies show that the ligand alkyl chain length has very little impact on HNO3 and H2O extraction, whereas the addition of 10% octanol significantly increases the extraction of both HNO3 and H2O. Viscosity and interfacial tension are impacted by HNO3 concentration, alkyl chain length, and the presence of phase modifier but remain in a range that should be compatible with commonly used solvent-contacting equipment. Additional studies of physicochemical properties at variable ligand concentrations suggest that a change in aggregation occurs above a ligand concentration of approximately 10-50 mM. Thermodynamic modeling of distribution ratios and spectroscopic studies aimed at understanding speciation in the presence of HNO3 are also reported. These experiments suggest that the first equivalent of extracted HNO3 interacts with both the central amine and the carbonyl groups of the ligand. The spectroscopic changes at higher HNO3 concentrations are relatively minor, suggesting that additional HNO3 is associated in an outer-sphere manner.

A promising metal-organic complex, iron (Fe)-NTMPA 2 , consisting of Fe(III) chloride and nitrilotri-(methylphosphonic acid) (NTMPA), is designed for use in aqueous iron redox flow batteries. A full-cell testing, where a concentrated Fe-NTMPA 2 anolyte (0.67 M) is paired with a Fe-CN catholyte, demonstrates exceptional cycling stability over 1000 charge/discharge cycles, and noteworthy performances, including 96% capacity utilization, a minimal capacity fade rate of 0.0013% per cycle (1.3% over 1,000 cycles), high Coulombic efficiency and energy efficiency near 100% and 87%, respectively, all achieved under a current density of 20 mA·cm - ². Furthermore, density functional theory unveils two potential coordination structures for Fe-NTMPA 2 complexes, improving the understanding between the ligand coordination environment and electron transfer kinetics. When paired with a high redox potential Fe-Dcbpy/CN catholyte, 2,2′-bipyridine-4,4′-dicarboxylic (Dcbpy) acid and cyanide (CN) ligands, Fe-NTMPA 2 demonstrates a notably elevated cell voltage of 1 V, enabling a practical energy density of up to 9 Wh/L.

Nuclear waste repository designs require backfill materials to contain long-lived radionuclides, including technetium-99, present as the pertechnetate anion (TcO4-) under oxic repository conditions and mobile in the environment. Bentonite has been proposed as a suitable backfill material, and it is composed of montmorillonite clay, which can be functionalized to optimize its performance for TcO4- sorption. In the current work, bentonite clay is functionalized with organic and inorganic moieties, and the impact of dual functionalization on TcO4- sorption is investigated. The results show that the ordering of the functionalization is essential and that adding metal to an organoclay improves TcO4- sorption compared to either the reverse ordering or the organic/inorganic clay alone. Furthermore, the TcO4- sorption to the organometallic clays was consistent with either chemisorption or cooperative sorption, with a multi-step mechanism determining the kinetics of sorption.

Light-induced electron transfer between chromophoric organic matter and Fe(III)-oxides lies at the heart of aqueous Fe(II) fluxes in the photic zone of natural systems. Understanding this photoreductive dissolution process is also essential for developing water purification techniques based on this class of materials. Previously, optical transient absorption spectroscopy (TAS) measurements revealed that nanosecond relaxation times of photoexcited rhodamine B (RhB) dye increased when sorbed onto hematite nanoparticles (HNPs), consistent with electron transfer to the oxide. In the present study, we exploit time-resolved X-ray absorption spectroscopy (XAS) at the Fe K-edge to follow the Fe oxidation state for this same process to (i) confirm that RhB photoexcitation leads to interfacial electron transfer and Fe reduction and (ii) quantify the lifetime of injected electrons as a function of solution conditions. Regardless of RhB dye availability and pH, direct band gap photoexcitation of HNPs yields an Fe(II)-like small polaronic absorption signature with a lifetime of similar to 1 ns, an order of magnitude longer than previously reported. However, when RhB is present at low pH under conditions where dye favorably interacts with the positively charged hematite surface, a second relaxation process approaching microsecond time scales is observed that likely represents back-reaction with the photoexcited adsorbed dye. At pH above neutral, the efficiency of the interfacial electron transfer is diminished by a weaker interaction between sorbed dye and particle surfaces.

Ceria nanomaterials with facile Ce-III/IV redox behavior are used in sensing, catalytic, and therapeutic applications, where inclusion of Ce-III has been correlated with reactivity. Understanding assembly pathways of CeO2 nanoparticles (NC-CeO2) in water has been challenged by "blind" synthesis, including rapid assembly/precipitation promoted by heat or strong base. Here, we identify a layered phase denoted Ce-I with a proposed formula Ce-IV(OH)(3)(NO3)xH(2)O (x approximate to 2.5), obtained by adding electrolytes to aqueous cerium ammonium nitrate (CAN) to force precipitation. Ce-I represents intermediate hydrolysis species between dissolved CAN and NC-CeO2, where CAN is a commonly used Ce-IV compound that exhibits unusual aqueous and organic solubility. Ce-I features Ce-(OH)(2)-Ce units, representing the first step of hydrolysis toward NC-CeO2 formation, challenging prior assertions about Ce-IV hydrolysis. Structure/composition of poorly crystalline Ce-I was corroborated by a pair distribution function, Ce-L3 XAS (X-ray absorption spectroscopy), compositional analysis, and O-17 nuclear magnetic resonance spectroscopy. Formation of Ce-I and its transformation to NC-CeO2 is documented in solution by small-angle X-ray scattering (SAXS) and in the solid-state by transmission electron microscopy (TEM) and powder X-ray diffraction. Morphologies identified by TEM support form factor models for SAXS analysis, evidencing the incipient assembly of Ce-I. Finally, two morphologies of NC-CeO2 are identified. Sequentially, spherical NC-CeO2 particles coexist with Ce-I, and asymmetric NC-CeO2 with up to 35% Ce-III forms at the expense of Ce-I, suggesting direct replacement.

Directing divalent metals to form either M(II) or M(II)-OH cationic species on the same support could provide an opportunity to compare their reactivity, if successful. Utilizing H-BEA zeolites with similar Si/Al ratios but with differing framework Al siting, we anchored multiple divalent metal cations (Ni, Pd, Pt, Cr, Cu) in the zeolite micropores. State-of-the-art infrared (IR) spectroscopy, electron paramagnetic resonance (EPR) measurements, including 2-dimensional pulsed HYSCORE EPR, EXAFS, and density functional theory (DFT) calculations provide unambiguous evidence for the selective formation of divalent metal cations as M+2/2Al species (for conventional zeolite prepared in the hydroxide media), and [M(II)-OH]+1/1Al species for H-BEA prepared in HF. This allowed us to explore their reactivities in the most important catalytic and adsorptive applications, which was not previously possible both in organometallic homogeneous and heterogeneous catalysis: we provide evidence for their divergent reactivity in ethylene dimerization, ethylene oxidation (Wacker process), selective catalytic reduction (SCR) of NO, NO adsorption, and methane oxidation. M+2/2Al and [M(II)-OH]+1/1Al species are both active for ethylene dimerization (including the first example of Pt/Zeolite reactivity for ethylene oligomerization), with [M(II)-OH]+1/1Al being more active in all cases (Pd, Ni, Pt). [M(II)-OH]+1/1Al is active for acetaldehyde formation in Wacker ethylene oxidation. We also propose the existence of a new active site with a terminal OH group (Cr-OH) in Phillips catalysts for ethylene oligomerization, as isolated Cr in BEA zeolite is virtually inactive, whereas Cr-OH shows activity in ethylene dimerization

We show that replacing alkaline (NaOH) for alkaline-earthmetal (Sr(OH)2 as an example) in the synthesis of SSZ-13 zeolitewith Si/Al~10 produces SSZ-13 zeolite material with novel, advantageousproperties. Its NH4-form ion-exchanges higher amount of Co(II) ionsthan the conventional one: this is the consequence of increased number of Al pairsin the structure induced by the +2 charge of Sr(II) cations in the synthesisgel that force two charge-compensating AlO4- motives tobe closer together. We characterize the +2 state of Co(II) ions in thesematerials with infra-red spectroscopy and XANES measurements. They can be usedfor NOx pollutant adsorption from ambient air: the ones derived from SSZ-13with higher Al pair content contain more cobalt(II) and thus, perform better asambient-air NOx adsorbers before reaching full saturation capacity. Notably,Co(II)/SSZ-13 material with increased number of Al pairs is significantly morehydrothermally stable than its NaOH-derived analogue. Loading 1.7 wt% Pd intoCo-SSZ-13 synthesized in the presence of Sr(II) produces a passive NOxadsorber (PNA) material that can be used for NOx adsorption from simulateddiesel engine exhaust. The critical issue for these applications ishydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in NaOH medialoses most of its PNA capacity after ~800 ⁰Chydrothermal aging in the flow of air and steam (10 hours in 10% H2O/airflow). The 1.7 wt% Pd/Co/SSZ-13 material with Si/Al ~10 does not lose its PNAcapacity after extremely harsh aging at 850 and 900 ⁰C (10 hours in 10% H2O/Air flow)and loses only ~55% capacity after hydrothermal aging at 930 ⁰C. It shows considerably enhanced stabilitycompared with previous record for Pd/FER, Pd/SSZ-39 and Pd/BEA materials thatcould survive hydrothermal aging no higher than 820 ⁰C. We herein reveal a new, simple, andscalable strategy for making remarkably (hydro)thermally stable metal-zeolitematerials/catalysts with a number of useful applications.