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DOE OSTI · 2564884

Nickel promotes selective ethylene epoxidation on silver

Jalil, Anika [University of California, Santa Barbara, CA (United States)] (ORCID:000000019581731X)·Happel, Elizabeth E. [Tufts University, Medford, MA (United States)]·Cramer, Laura [Tufts University, Medford, MA (United States)] (ORCID:0000000156008317)·Hunt, Adrian [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000252839647)·Hoffman, Adam S. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000276824108)·Waluyo, Iradwikanari [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000240469722)·Montemore, Matthew M. [Tulane University, New Orleans, LA (United States)] (ORCID:0000000241571745)·Christopher, Phillip [University of California, Santa Barbara, CA (United States)] (ORCID:0000000248985510)·Sykes, E. Charles H. [Tufts University, Medford, MA (United States)] (ORCID:0000000202242084)
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Abstract

Over the last 80 years, chlorine (Cl) has been the primary promoter of the ethylene epoxidation reaction valued at ~40 billion USD per year, providing a ~25% selectivity increase over unpromoted silver (Ag) (~55%). Promoters such as cesium, rhenium, and molybdenum each add a few percent of selectivity enhancements to achieve 90% overall, but their codependence on Cl makes optimizing and understanding their function complex. Here, we took a theory-guided, single-atom alloy approach to identify nickel (Ni) as a dopant in Ag that can facilitate selective oxidation by activating molecular oxygen (O 2 ) without binding oxygen (O) too strongly. Surface science experiments confirmed the facile adsorption/desorption of O 2 on NiAg, as well as demonstrating that Ni serves to stabilize unselective nucleophilic oxygen. Supported Ag catalyst studies revealed that the addition of Ni in a 1:200 Ni to Ag atomic ratio provides a ~25% selectivity increase without the need for Cl co-flow and acts cooperatively with Cl, resulting in a further 10% initial increase in selectivity.

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36 MATERIALS SCIENCE37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

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Jalil, Anika [University of California, Santa Barbara, CA (United States)] (ORCID:000000019581731X), Happel, Elizabeth E. [Tufts University, Medford, MA (United States)], Cramer, Laura [Tufts University, Medford, MA (United States)] (ORCID:0000000156008317), Hunt, Adrian [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000252839647), Hoffman, Adam S. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000276824108), Waluyo, Iradwikanari [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000240469722), Montemore, Matthew M. [Tulane University, New Orleans, LA (United States)] (ORCID:0000000241571745), Christopher, Phillip [University of California, Santa Barbara, CA (United States)] (ORCID:0000000248985510), Sykes, E. Charles H. [Tufts University, Medford, MA (United States)] (ORCID:0000000202242084). 2025-02-20. Nickel promotes selective ethylene epoxidation on silver. https://doi.org/10.1126/science.adt1213

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DOE OSTI2026

Cyclic moisture reactivation of calcium sorbents for long duration thermochemical energy storage

The transition to a flexible and reliable energy infrastructure, using electro-thermal energy generation technologies such as geothermal, concentrated solar power, and nuclear, usually demands simultaneous advancement of thermal energy storage (TES) to support on-demand electricity generation and industrial applications while mitigating the inherent intermittency of renewable energy sources and power outages from direct energy generation. Among TES technologies, thermochemical energy storage (TCES) based on calcium looping emerges as a compelling high-power energy storage candidate due to its high reaction enthalpy, compatibility with elevated operating temperatures, and abundance of low-cost materials. However, the long-term durability of calcium-based sorbents for TCES is hindered by surface sintering and particle aggregation, leading to performance degradation over repeated thermal cycles. This study explores a moisture hydration-based strategy to regenerate a degraded calcium sorbent and mitigate performance degradation for long duration TCES. The addition of moisture transforms calcium oxide into calcium hydroxide and produces intercalation water layers, associated with a regenerated surface area and reduced calcium oxide crystallite size. Both these effects are beneficial in restoring the sorbents' reactivity for carbonization. Additionally, an optimized hydration-assisted reactivation protocol balances the recovered energy storage capacity with heating penalty required for moisture removal from hydrated samples, resulting in an enhanced energy storage capacity up to 176% compared to benchmark sorbents that undergo cycling without reactivation after 60 cycles. In conclusion, these results highlight the potential of hydration-assisted reactivation to enhance the long-term performance of TCES, providing an effective pathway to advancing electro-thermal storage technologies.

36 MATERIALS SCIENCE↗