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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

A Highly Porous and Robust (3,3,4)-Connected Metal-Organic Framework Assembled with a 90° Bridging-Angle Embedded Octacarboxylate Ligand

A dicopper(II)-paddle-wheel-based metal-organic framework (PCN-80, see picture) with a rare (3,3,4)-connected topology has been synthesized by using a unique octatopic ligand featuring 90° bridging-angle dicarboxylate moieties. PCN-80 has Brunauer-Emmett-Teller (BET) and Langmuir surface areas of 3850 and 4150 m 2 g -1 , respectively. It exhibits high gas-uptake capacity for H 2 and large adsorption selectivity of CO 2 over N 2 .

08 HYDROGEN↗
DOE OSTI2014

Solvent-Assisted Linker Exchange: An Alternative to the De Novo Synthesis of Unattainable Metal-Organic Frameworks

Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials—in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function–property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Flexible Zirconium Metal‐Organic Frameworks as Bioinspired Switchable Catalysts

Abstract Flexible metal–organic frameworks (MOFs) are highly desirable in host–guest chemistry owing to their almost unlimited structural/functional diversities and stimuli‐responsive pore architectures. Herein, we designed a flexible Zr‐MOF system, namely PCN‐700 series, for the realization of switchable catalysis in cycloaddition reactions of CO 2 with epoxides. Their breathing behaviors were studied by successive single‐crystal X‐ray diffraction analyses. The breathing amplitudes of the PCN‐700 series were modulated through pre‐functionalization of organic linkers and post‐synthetic linker installation. Experiments and molecular simulations confirm that the catalytic activities of the PCN‐700 series can be switched on and off upon reversible structural transformation, which is reminiscent of sophisticated biological systems such as allosteric enzymes.

Yuan, Shuai↗
DOE OSTI2015

PdHx entrapped in covalent triazine framework modulates selectivity in glycerol oxidation [Modulation of palladium activity and stability by a covalent triazine framework]

The confinement of a Pd nanoparticle within a nitrogen-containing covalent triazine framework (CTF) material was investigated to understand if the highly tunable CTF chemistry mediates the Pd catalytic properties through an ensemble effect with the CTF nitrogen atoms or a confinement effect within the CTF pores. The results surprisingly demonstrate that the CTF stabilizes the formation of 2.6 nm PdHx particles within the pores. These PdHx particles are very active for the liquid phase oxidation of glycerol due to the in situ formation of H2O2 which catalytically promotes the initial C-C cleavage. In addition the confined particles are stable over many catalytic cycles whereas nanoparticles trapped outside of the pores loose activity rapidly. These results indicate that there is the potential to tune the CTF chemistry to significantly modify the chemistry of the catalytic metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

In Operando Analysis of Diffusion in Porous Metal‐Organic Framework Catalysts

Abstract The potential to exert atomistic control over the structure of site‐isolated catalyst sites, as well as the topology and chemical environment of interstitial pore spaces, has inspired efforts to apply porous metal‐organic frameworks (MOFs) as catalysts for fine chemical synthesis. In analogy to enzyme‐catalyzed reactions, MOF catalysts have been proposed as platforms in which substrate confinement could be used to achieve chemo‐ and stereoselectivities that are orthogonal to solution‐phase catalysts. In order to leverage the tunable pore topology of MOFs to impact catalyst selectivity, catalysis must proceed at interstitial catalyst sites, rather than at solvent‐exposed interfacial sites. This Minireview addresses challenges inherent to interstitial MOF catalysis by 1) describing the diffusional processes available to sorbates in porous materials, 2) discussing critical factors that impact the diffusion rate of substrates in porous materials, and 3) presenting in operando experimental strategies to assess the relative rates of substrate diffusion and catalyst turnover in MOF catalysis. It is anticipated that the continued development of in operando tools to evaluate substrate diffusion in porous catalysts will advance the application of these materials in fine chemical synthesis.

Gao, Wen‐Yang↗
DOE OSTI2017

Application-level regression testing framework using Jenkins

Monitoring and testing for regression of large-scale systems such as the NCSA's Blue Waters supercomputer are challenging tasks. In this paper, we describe the solution we came up with to perform those tasks. The goal was to find an automated solution for running user-level regression tests to evaluate system usability and performance. Jenkins, an automation server software, was chosen for its versatility, large user base, and multitude of plugins including collecting data and plotting test results over time. We also describe our Jenkins deployment to launch and monitor jobs on remote HPC system, perform authentication with one-time password, and integrate with our LDAP server for its authorization. We show some use cases and describe our best practices for successfully using Jenkins as a user-level system-wide regression testing and monitoring framework for large supercomputer systems.

97 MATHEMATICS AND COMPUTING↗