Category: Seminars

Pt-Re Interactions under Hydrothermal Conditions for Aqueous Phase Reforming of Bio-derived Liquids

Wednesday, October 6, 2010 11:00 am – 12:00 pm
Room 610, M&M Building

David L. King
Pacific Northwest National Laboratory

Abstract

Hydrogen production from the aqueous phase reforming of glycerol over 3%Pt-Re/C  has beenstudied,  and the results compared with a Re-free 3%Pt/C catalyst. Although the Pt/C catalyst isvery selective toward the production of hydrogen, catalytic activity is low. Addition of Resignificantly increases the conversion of glycerol, at some loss of hydrogen selectivity to lighthydrocarbons and water-soluble oxygenates. This loss of H2 selectivity can be traced to anincrease in acid-catalyzed dehydration pathways.  The highest hydrogen productivity among thecatalysts tested is achieved with a 3%Pt-3%Re/C catalyst with added KOH base, whichmediates the acidity. The observed product distributions can be understood in terms of thedifferent reaction pathways that become emphasized depending on catalyst composition andpH.

The structure of Pt-Re nanoparticles supported on carbon following exposure to a hydrogenreducing environment and subsequent hydrothermal conditions has been studied using in-situ xray photoelectron spectroscopy (XPS) and aberration-corrected scanning transmission electronmicroscopy (STEM) with associated energy-dispersive spectroscopy (EDS). Thephysicochemical and electronic structure of PtRe nanoparticles under hydrothermal conditionshave been correlated to the catalyst selectivity in the aqueous phase reforming of glycerol. Weshow that Re addition to Pt results in charge transfer from Pt to Re-Ox under hydrothermalreaction conditions. The catalyst acidity increases with increasing Re:Pt ratio, and the higheracidity is shown to favor C-O over C-C cleavage. This results in higher selectivity to liquidproducts and alkanes at the expense of hydrogen production. We discuss the possible origins ofacidity enhanced by the addition of Re.

Biography

Dr. David L. King is a Laboratory Fellow (the highest rank that PNNL science and engineering staff canattain) and Team Lead of the Catalysis Science and Application Group at Pacific Northwest National Laboratory(PNNL) in Richland, Washington.  He is currently Associate Lead for the Energy Conversion Initiative, a laboratorylevel initiative which has as its goal to develop PNNL as a Center of Excellence for Air- and Water-NeutralHydrocarbon Conversions, with a major focus on clean coal. He has had a long-standing interest in production ofhydrocarbon liquids from coal and biomass. Dr. King holds fifteen patents, with several pending, and over forty peerreviewed publications. Dr. King has a Ph. D. from Harvard University in physical chemistry.


Composite Materials in Large Civil Engineering Structures – Design Optimization

Friday, October 1, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

John Pilling
Technical Director, Electric Park Research

Abstract

The choice of materials for use in load bearing civil engineering structures are often determined by costsimply because of the large volumes of materials involved.  One instance of the large scale use ofpolymeric materials is in the rehabilitation of cracked, corroded or collapsed pipes that were originallyinstalled under most of the large American cities during the late 1800s. In many instances it is extremelycostly or impossible to dig up and replace the existing pipes. Rehabilitation by lining the pipes with apolymeric material is common practice. HDPE is currently favoured for small diameter internallypressurized pipes such as water and gas mains and is usually pulled into and through the existing pipes.However, this is not practical for many of the waste and storm water pipes that are either non-circular orlarger than about 24” in diameter as the pipe wall becomes excessively thick in order to support theimposed loads without buckling or fracture.  Combining micromechanics of materials, elasticity theory oflaminates, and a geotechnical analysis of the loading of buried pipes, it is possible to design compositestructures that can support all the imposed loads and be easily installed in the existing collapsed pipe.The design process involves a geotechnical analysis of the imposed soil, water and rolling loads (vehicle,rail or aircraft) to determine the imposed pressure on the pipe. The pressure that a given pipe wall willsupport depends on the flexural rigidity of the  pipe wall (EI), its strength (s)  and a critical designdimension (D), usually the diameter of the pipe, but can be a critical radius of curvature or the length of astraight section when the pipe is non-circular. The actual equations used to determine the pressure thatcan be supported depend on the shape of the pipe, the type of loading and the country in which the pipeis to be installed (National Design Codes).  An “Ashby” type analysis is then completed in which therequired pipe thickness to support the imposed loads is determined as a function of the internal structureof a laminated composite given that the mechanical properties of the pipe wall are themselves functionsof thickness. The cost of the design is then calculated.  Typical microstructural variables include the typeof reinforcing fibre, the fibre spacing (volume fraction), resin type and fibre position within the laminatedstructure, i.e thickness.  A numerical solution method is employed to determine the combination ofmicrostructural variables that produce the composite with the minimum cost. Each rehabilitation projectproduces a unique composite microstructure which can be easily manufactured, on demand, usingtechnology currently deployed in the textile industry.  Typical municipal rehabilitation projects cangenerate material costs savings in the millions of $ range over conventional monolithic materials.  Thispresentation explains how micromechanics and elasticity theory are combined with typical civilengineering design codes to produce cost minimized structural composites. Examples of pipes andinstallations will be included.


Innovation in Metals Production – Faster, Cheaper, Safer

Wednesday, September 29, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

Prof. David Robertson
Department of Materials Science and Engineering
Missouri University of Science and Technology
Rolla, MO

Abstract

Metals constitute an important class within the more general category of materialsand steel is by far the most produced of all the metals.  The lecture will giveexamples of how basic scientific knowledge is gained and then used to meet thetechnical challenges and opportunities that arise as we strive to satisfy the everrising demand for metals in a world where sustainability is a vital issue.

Biography

David Robertson is Professor Emeritus at the Missouri University ofScience and Technology.  He was the TMS Extractive Metallurgy Lecturer in 2008and Director of the national Center for Pyrometallurgy (funded by the US Bureauof Mines) from 1985-1996.  Dr. Robertson’s teaching and research interests havecovered the smelting and refining of all the metals – from aluminum through copperand steel to zinc.  He and his colleagues have always worked closely withindustry, both in the US and internationally. The citation for the Elliott LecturerAward reads:  “For application of process modeling to steel refining technology,and for advances in quantitative analysis of metallurgical processes.


Introduction to Pearson’s Crystal Data Software TUTORIAL

Friday, September 17, 2010 3:00 pm – 4:00 pm
Room 610, M&M Building

Edward A. Laitila
Department of Materials Science and Engineering
Michigan Technological University

Abstract

A new software package, Pearson’s Crystal Data, is available to the campuscommunity. The software has been deployed to select areas of the campus.Pearson’s Crystal Data contains a large amount of information on crystallineinorganic materials and would be beneficial to anyone working with solidcrystalline materials. Information in the database includes atomic positions,symmetry data, crystal models, lattice parameters, x-ray diffraction spectra, andmore. An introduction to the software will be provided along with a tutorial of thebasic searching functions. Advanced searches will be introduced as well as thevarious types of data presentation along with tips on how to export importantinformation.

Individuals are welcome to install the software on their laptops and bring it tofollow along the tutorial.


Channel Saturation and Conductance Quantization in Metal Point Contacts

Friday, September 10, 2010 10:00 am – 11:00 am
Room 610, M&M Building

Harsh Deep Chopra
Laboratory for Quantum Devices, Materials Program
Mechanical & Aerospace Engineering Department
The University at Buffalo, The State University of New York, Buffalo, NY

Abstract

Notwithstanding the discreteness of metallic constrictions, it is shown for the first timethat the finite elasticity of stable, single-atom gold constrictions allows for a continuousand reversible change in conductance, thereby enabling direct observation of channelsaturation and conductance quantization. The observed channel saturation andconductance quantization under strain perturbation is achieved by superposition ofatomic/subatomic-scale oscillations on a retracting/approaching gold tip against a goldsubstrate of a scanning probe. Results also show that conductance histograms, whoseuse is considered de rigueur in analysis, are neither suitable for evaluating the stability ofatomic configurations through peak positions or peak height nor appropriate forassessing conductance quantization. A large number of atomic configurations withsimilar conductance values give rise to peaks in the conductance histogram. Thepositions of the peaks and counts at each peak can be varied by changing the conditionsunder which the histograms are made. Histogram counts below 1Go cannot necessarilybe assumed to arise from single-atom constrictions.

Biography

Harsh Deep Chopra (pronounced as ‘Hersh’) is Professor in Mechanical &Aerospace Engineering Department at SUNY-Buffalo, which hosts the Materials Program.Chopra graduated from the University of Maryland’ Materials Department in December 1993.After postdoctoral experience at NIST and Monash University, he joined SUNY-Buffalo inJanuary 1998. Chopra’s primary research interests are focused on single-atom spintronics;mechanics, electronics, and magnetism in atomic sized systems; magnetic functional material(magnetic shape memory alloys, magnetostrictive materials) in thin films, multilayers, and bulkforms; micromagnetic fractals; transport/thermal properties in small systems.


Ceramic Matrix Composite Insertion into Nozzles for Gas Turbine Engines

Thursday, May 20, 2010 11:00 am – 12:00 pm
Room 610, M&M Building

Greg C. Ojard
Advanced Materials Group
Pratt & Whitney
East Hartford, CT

Abstract

Ceramic matrix composites (ceramic fiber in a ceramic matrix) have the promise ofproviding significant efficiency and durability improvements for gas turbine enginesbecause the material has essentially constant strength with temperature.  Thisallows higher engine operating temperatures without the need for cooling air.  Forany material, the characterization of the material and its resulting performance iskey in determining its usefulness for a given application.  Additionally, long termtesting and resulting residual capability is critical to understanding the durability ofthe material.  Such results will be shown for a characterization effort on novelSiC/SiC and C/SiC material systems.  Results from engine testing will also beshown as well as limited flight testing information.

Biography

Greg Ojard is the Discipline Chief for the Advanced Materials Group in Materials &Processes Engineering at Pratt & Whitney.  He has 18 years of experience in characterizingmaterials for aerospace applications.  He spent his first 5 years developing and performingultrasonic inspections on a wide range of development material and aerospace hardware.  Forthe last 13 years he has worked on characterizing ceramic matrix composites, ceramics andceramic coatings for hot sections in gas turbine engines.  He has been the lead engineer onseveral ceramic matrix composite characterization efforts leading to insertion and flight testopportunities. He holds 2 patents and has over 45 publications. He is also an Adjunct Professorat the University of New Haven teaching materials selection courses.  He earned his PhD fromIowa State University in Metallurgy in 1991.  He has his BS and MS degrees in MetallurgicalEngineering from Michigan Technological University in 1986 and 1988.


Mixed Conducting Ceramic Membrane Reactors

Friday, April 23, 2010 11:00 am – 12:00 pm
Room 610, M&M Building

Susan M. Stagg-Williams
University of Kansas
Lawrence, Kansas

Abstract

Mixed oxygen ionic-electronic conductive (O-MIEC) perovskites have gainedsignificant attention as desirable materials for catalytic reactors because of theirability to separate oxygen from air without the use of an external circuit.  Themembranes have an infinite theoretical oxygen separation factor and can be usedfor staged addition of oxygen to reactors.  One specific application of interest isthe production of synthesis gas (H2 and CO) via simultaneous oxygen separationand hydrocarbon conversion.  However, many of the perovskite or perovskite-likemembranes being investigated suffer from low oxygen flux or mechanicalinstability.  Work at the University of Kansas is focused on the production of highflux oxygen permeable membranes with the mechanical integrity to be used ashigh temperature reactors and in highly reducing environments.  This seminar willoutline strategies for increasing oxygen flux through ceramic membranes andshow examples of reactor applications using these high flux membranes.


Nanogenerators for Self-Powered Nanosystems

Thursday, April 22, 2010 10:00 am – 11:00 am
Room G06, Rekhi Hal

Rusen Yang
School of Materials Science and Engineering
Georgia Institute of Technology
Atlanta, GA

Abstract

A self-powered nanosystem that harvests its operating energy from the environment isan attractive proposition for sensing, medical science, defense technology, and evenpersonal electronics. Therefore, it is essential to explore innovative nanotechnologies forconverting mechanical energy (such as body movement), vibration energy (such asacoustic/ultrasonic wave), and hydraulic energy (such as blood flow) into electric energythat will be used to power nanodevices without using battery. Piezoelectric zinc oxidenanowire (NW) arrays have been successfully demonstrated to convert nano-scalemechanical energy into electric energy. The operation mechanism of the electricgenerator relies on the unique coupling of piezoelectric and semiconducting dualproperties of ZnO as well as the elegant rectifying function of the Schottky barrier formedbetween the metal electrode and the NW. This mechanism resulted in the DCnanogenerator driven by ultrasonic wave. Recently we achieved a new breakthroughwith laterally-packaged single wire generator, which solved the transient contact issue inDC nanogenerator and produced power output from low frequency and irregularmechanical disturbance, such as finger tapping and running hamster. This presentationwill introduce the fundamental principle of nanogenerator and its potential applications.


On the Genesis of Nuclei and Phase Separation on an Atomic Scale

Tuesday, April 13, 2010 1:00 – 2:00 pm
Room 610, M&M Building

Professor David N. Seidman
Department of Materials Science and Engineering
Northwestern University
Evanston, Illinois

Abstract

Phase separation in the condensed state of matter is of general scientific interestas well as being technologically important.  It commences with the formation ofsubnanometer diameter nuclei, which subsequently evolve temporally by growingand coarsening.  Hence, it is the kinetics of phase separation that ultimately leadsa system to its equilibrium thermodynamic state.  In this colloquium I will showhow atom-probe tomography is utilized to follow, on an atomic scale, the kineticsof phase separation in ternary alloys, Ni-Al-Cr, beginning with the clustering ofatoms to form nuclei that evolve into a precipitates that have an ordered crystalstructure.  In parallel with the experiments lattice kinetic Monte Carlo simulationsare performed, whose results help in obtaining a detailed atomistic understandingof the underlying mechanisms by which phase separation occurs.  The atomprobe tomographic results taken in concert with the lattice kinetic Monte Carlosimulations yield a physical portrait that provide a deeper physical understandingof phase separation in a concentrated multicomponent alloy than has heretoforebeen possible.