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Abstract Olefin oligomerization by γ‐Al₂O₃has recently been reported, and it was suggested that Lewis acid sites are catalytic. The goal of this study is to determine the number of active sites per gram of alumina to confirm that Lewis acid sites are indeed catalytic. Addition of an inorganic Sr oxide base resulted in a linear decrease in the propylene oligomerization conversion at loadings up to 0.3 wt %; while, there is a >95 % loss in conversion above 1 wt % Sr. Additionally, there was a linear decrease in the intensity of the Lewis acid peaks of absorbed pyridine in the IR spectra with an increase in Sr loading, which correlates with the loss in propylene conversion, suggesting that Lewis acid sites are catalytic. Characterization of the Sr structure by XAS and STEM indicates that single Sr²⁺ions are bound to the γ‐Al₂O₃surface and poison one catalytic site per Sr ion. The maximum loading needed to poison all catalytic sites, assuming uniform surface coverage, was ∼0.4 wt % Sr, giving an acid site density of ∼0.2 sites per nm²of γ‐Al₂O₃, or approximately 3 % of the alumina surface. 

Abstract We report a single atom Rh₁/CeO₂catalyst prepared by the high temperature (800 °C) atom trapping (AT) method which is stable under both oxidative and reductive conditions. Infrared spectroscopic and electron microscopy characterization revealed the presence of exclusively ionic Rh species. These ionic Rh species are stable even under reducing conditions (CO at 300 °C) due to the strong interaction between Rh and CeO₂achieved by the AT method, leading to high and reproducible CO oxidation activity regardless of whether the catalyst is reduced or oxidized. In contrast, ionic Rh species in catalysts synthesized by a conventional impregnation approach (e. g., calcined at 350 °C) can be readily reduced to form Rh nanoclusters/nanoparticles, which are easily oxidized under oxidative conditions, leading to loss of catalytic performance. The single atom Rh₁/CeO₂catalysts synthesized by the AT method do not exhibit changes during redox cycling hence are promising catalysts for emission control where redox cycling is encountered, and severe oxidation (fuel cut) leads to loss of performance. 

We review recent advances in software platforms for model-based design (MBD) organized in five overarching themes — from (1) simulation to optimization, (2) commercial to open-source, (3) process-centric to multiscale, (4) mechanistic to data-driven, and (5) deterministic to uncertain — illustrated with several recent examples in membrane system design. We posit MBD provides (chemical) engineers with principled frameworks to tackle global grand challenges such as sustainable energy, clean water, and equitable access to healthcare by integrating knowledge across disciplines. As such, we predict MBD software, which has historically focused on engineered systems, will evolve to interact with models for natural and social systems more holistically. Finally, we emphasize the importance of open-source software development, especially by users who become contributors. 

Doped perovskite metal oxide catalysts of the form A(B_xM_1-x)O_3-δhave been instrumental in the development of solid oxide electrolyzers/fuel cells. In addition, this material class has also been demonstrated to be effective as a heterogeneous catalyst. Co-doped barium niobate perovskites have shown remarkable stability in highly acidic CO₂sensing measurements/environments (1). However, the reason for their chemical stability is not well understood. Doping with transition metal cations for B site cations often leads to exsolution under reducing conditions. Many perovskites used for the oxidative coupling of methane (OCM) or the electrochemical oxidative coupling of methane (E-OCM) either lack long term stability, or catalytic activity within these highly reducing methane environments. The Mg and Fe co-doped barium niobate BaMg_0.33Nb_0.67-xFe_xO_3-δshown activity in E-OCM reactors over long periods (2) (>100 hrs) with no iron metal exsolution observed by diffraction or STEM EDX measurements. In contrast, iron decorated BaMg_0.33Nb_0.67O₃showed little C2 conversion activity.