Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session B31: Advances in Hierarchical Systems: Theory and Experiments IInvited
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Sponsoring Units: DCP Chair: Neeraj Rai, Mississippi State University; Dongxia Liu, University of Maryland Room: BCEC 203 |
Monday, March 4, 2019 11:15AM - 11:51AM |
B31.00001: Structure and reactivity of two-dimensional silica and zeolites Invited Speaker: Joachim Sauer Density functional theory is applied to solve the structures of ultrathin silica and zeolite films on metal substrates based on experimental information including LEED, IR-RAS, and STM. Specifically we discuss crystalline films consisting of one or two layers of corner-sharing TO4-tetrahedra (T=Si, Al) on Mo(112) and Ru(0001) surfaces. We also discuss the formation of amorphous phases that can be directly imaged in real space by STM, and the substitution of Si with Ti and Fe which is not isomorphous but leads to new structure types. |
Monday, March 4, 2019 11:51AM - 12:27PM |
B31.00002: Hierarchical Zeolites: Synthesis and Applications Invited Speaker: Michele Ostraat Zeolites have been used extensively as industrial solid-acid catalysts in the oil refining and petrochemical industries due to their unique pore structures, acidity, and stability. Over the past two decades, innovations in synthesizing hierarchical zeolites have received continuous attention in both academia and industry for the potential to optimize catalytic performance of zeolite materials for in a wide range of refining and petrochemical applications that involve conversion of bulky molecules. The manipulation of hierarchy in zeolites can be achieved by different synthetic strategies that result in distinctive zeolites with various morphological, structural, and compositional characteristics. In this talk, we will discuss our recent progress on developing and optimizing hierarchical zeolites using top-down routes as well as bottom-up approaches with hard and soft templates and will summarize many of the unique underlying features for these different synthesis routes and their implications for large-scale industrial production of zeolites. We will also provide highlights on the utilization of these materials for important industrial applications related to oil refining and chemical productions. |
Monday, March 4, 2019 12:27PM - 1:03PM |
B31.00003: 2D Materials and Membranes for Biorefining and Hydrocarbon Separations Invited Speaker: Sankar Nair The advent of 2D nanoporous materials has created exciting new possibilities in the scalable and economically viable fabrication of membranes for chemical separations. This talk will focus on our recent work in two areas of 2D membrane science and technology. Firstly, we will discuss new advances in the fabrication, modification, and scale-up of graphene oxide (GO) membranes, as well as their use in challenging applications in biorefining such as the fractionation of kraft black liquor and other related processes. Secondly, we will discuss our latest work on fabrication of 2D zeolite membranes on scalable hollow fiber platforms, and their applications in the separation of organic mixtures such as hydrocarbons from petrochemical processes or oxygenated molecules obtained from biomass conversion. |
Monday, March 4, 2019 1:03PM - 1:39PM |
B31.00004: Polymer-Grafted Nanoparticle Membranes with Unprecedented Gas-Separation Performance Invited Speaker: Sanat Kumar Recent work has shown that nanoparticles grafted with polymer chains (GNPs) possess unusual collective properties. Their gas permeability shows non-monotonic behavior with increasing polymer length, with peak permeability increases of 8-20 times relative to the neat polymer. Similarly, their mechanical properties change from brittle to tough around the chain length with peak gas permeability. We show by combining small angle x-ray scattering, x-ray photon correlation spectroscopy and linear rheology that this behavior reflects the transition of the GNP materials from a jammed, soft glass-like state to liquid-like behavior with increasing chain length. For chain lengths below this transition, polymers on adjacent nanoparticles do not interpenetrate. Polymer melt incompressibility then results in a system where the coronas distort so that they tile space yielding a jammed (disordered) colloidal state. At longer chain lengths, this colloidal behavior disappears because chains on adjacent coronas interpenetrate. Since the dynamic properties of these systems, spanning time scale from the ps to the macroscopic, are affected by this transition we postulate that all of their transport properties should show anomalous behavior. |
Monday, March 4, 2019 1:39PM - 2:15PM |
B31.00005: Regioselective Epoxide Ring Opening with Alcohols Using Heterogeneous Lewis Acidic Nano-Zeolites Invited Speaker: Nicholas Brunelli Epoxides are versatile intermediates that can be ring opened using different nucleophiles to produce a wide variety of valuable chemicals. The key challenge for this reaction is selectivity. The regioselectivity of epoxide ring opening reactions for alcohols is examined using Lewis acidic catalysts. Through comparing catalytic activities, it is found that Sn-Beta is more active than other similar Lewis acidic catalytic materials such as Sn-MFI and Sn-SBA-15. For all materials, high regioselectivity of >99% is obtained when using epichlorohydrin with methanol. With large substrates such as epoxy hexane, diffusion limitations are encountered that can be overcome through creating zeolites with particle sizes less than 100 nm such as nano-Sn-MFI. These materials can be readily recycled while retaining high catalytic activity and selectivity. Hot filtration tests demonstrate that these catalysts are heterogeneous in nature and stable. Larger substrates such as epoxy octane result in diffusion limitations. We demonstrate the use of a new SDA to produce nano-Sn-Beta. This material can catalyze even larger structures. Overall, this demonstrates the importance of tuning material design to create highly active catalytic materials. |
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