|
SUMMARIES OF FY 1996
RESEARCH IN THE CHEMICAL
SCIENCES |
Chemical Energy:
National Laboratory Projects
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
Organometallic Complexes in Homogeneous Catalysis
The aim of this research is to provide an understanding of the details of processes involving
homogeneous and heterogeneous catalysis. One such process is the hydrodesulfurization(HDS) of
petroleum feedstocks. From studies of model organometallic complexes of thiophene and related
organosulfur compounds, it has been established that 
-bonded thiophenes are activated to undergo reactions that lead to cleavage of the
carbon-sulfur bonds in the thiophene. Such reactions on HDS catalyst surfaces would be expected
to lead to desulfurization of the thiophene. To test this hypothesis, reactor studies of thiophene
with deuterium over molybdenum-based catalysts were performed. The deuterium location in the
butadiene product is consistent with activation of thiophene by -bonding to metal sites on the catalyst surface. Future studies include
exploring new approaches to the HDS of dibenzothiophenes, a family of compounds in petroleum
that are highly resistant to desulfurization. Other studies involve measurements of the strength of
adsorption of isocyanide ligands on metal surfaces and investigations of reactions of isocyanides
that are catalyzed by the metal surfaces.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
Chemical Kinetics and Reactivity of Transition Metal Complexes
New catalytic reactions are being developed to learn what otherwise-sluggish but important
reactions can be made to occur, and to understand how they take place, with a goal of developing
new processes. These reactions relate to environmentally-benign chemical processing and to
selective oxidations. The effects of catalyst composition, reagent concentrations, structural
variations, solvents, salts, etc. are being used to determine their mechanisms. A major target is
selective oxidation, presently with hydrogen peroxide but with oxygen activation as a secondary
goal. Methylrhenium trioxide (MTO), a soluble organometallic oxide, activates hydrogen peroxide
for catalytic attack by a significant number of substrates. Sulfides, phosphines, styrenes, alkenes,
alkynes, anilines, 
-diketones and halide
ions are among the molecules that can be efficiently oxygenated by the rhenium catalyst. The
mechanism involves a peroxorhenium intermediate that contains an electrophilically activated
peroxide chelated to rhenium. From these findings we postulated that a "carbene
equivalent" might be able to engage in the catalytic transfer of a carbene unit, just as the
peroxo complex transfers an "oxene" (i.e., an O atom). For example, it should be able
to convert an alkene to a cyclopropane, analogous to the conversion of an alkene to an epoxide.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
Fundamental Studies of Supported Metal Catalysts
The fundamental processes occurring at the surface of heterogeneous catalysts are investigated by
a combination of NMR with traditional techniques (kinetic studies, selective chemisorption,
infrared spectroscopy). We are focused on catalysts that find numerous applications in the
petroleum and chemical industries and in pollution control technology. Most of our effort in this
area is concentrated on characterizing the surfaces of working catalysts, probing the
chemisorption behavior and surface reaction of various molecules and studying the synergistic
effects of adding a second element; the second element can be another metal to form a bimetallic
or it can be a promoter, poison or a support modifier. The other area of effort in our program is
the application of new nuclear spin dynamics and new solid state NMR techniques to studies of
glasses, thin diamond films and zeolites. This program develops and applies solid-state NMR
techniques to significant problems in catalysis and surface science as well as other areas in
material science. Recent catalytic work has demonstrated the ability of solid state NMR to probe
the kinetics of hydrogen chemisorption on supported metal catalysts. For example, it was found
that small ruthenium particles (25% dispersion) had a sticking coefficient for hydrogen adsorption
significantly higher than ruthenium single crystals. However, the introduction of Ag reduced the
apparent sticking coefficient to the values seen on Ru(001). It was postulated that Ag blocked
edge and corner sites which are significantly more active than basal planes for hydrogen
adsorption. Microcalorimetry studies of these same catalysts gave complementary information.
Other recently completed work investigated CO and hydrogen adsorption on
Rh6/NaY catalysts via 1H and 13C NMR and
microcalorimetry. Also, crotonaldehyde selective hydrogenation over Pt bimetallic catalysts was
studied.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
New Synthetic Routes to Inorganic Catalytic Materials Using Organometallic Precursors and
Molecular "Stepping Stones"
My group's research objective in this program is to explore and develop new strategies toward the
synthesis and characterization of novel inorganic solids for potential applications in catalysis and
energy storage. We combine aspects of both organometallic and solid state chemistry in order to
synthesize transition metal compounds with metal-metal bonds that adopt either layered or
microporous morphologies. Our initial efforts are directed toward layered materials containing
reduced Nb3 and Ta3 triangles. Compounds we have synthesized
and characterized can be reduced by up to two electrons per formula without decompositions or
significant structural change. Intercalation and hydrogen activation studies are currently
underway.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
Solid State NMR Studies: Catalytic Chemistry and Materials
Transient techniques in nuclear magnetic resonance (NMR) are used to probe the physics and
chemistry of materials involved in heterogeneous catalysis and material science. Examples of
recent studies include: (1) in situ 1H NMR investigations of the dynamic behavior
(adsorption, desorption, motions, exchange phenomena) and reaction of hydrogen and small
hydrocarbon molecules on silica and alumina supported metallic catalysts (e.g.,
Rh/Al2O3, Rh-Pt/Al2O3,
Ru/SiO2) in temperature and pressure range used in important industrial
applications; (2) high resolution 1H and 13C studies of hydrogen,
CO and small hydrocarbon molecules on small rhodium clusters in Rh exchanged NaY zeolite; (3)
measurement of high-resolution NMR spectra of half-integer quadrupolar nuclei using the recently
developed two dimensional multiple quantum MAS NMR experiment. Other projects include
development of new research capabilities in solid state NMR (e.g., a combination of in situ NMR
with mass spectrometry), and application of new nuclear spin dynamics to the studies of surfaces
and surface phenomena.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
Spectroscopic and Kinetic Characterization of Metal Oxide Catalysts
This research is providing new fundamental information about catalysis by metal oxides, including
the mechanisms of catalytic reactions, the structure and composition of catalysts, and the
properties of surfaces. The metal oxides being investigated are used extensively by industry for
selective oxidation, particularly for the activation of paraffins for fuels and chemicals production.
A complement of experimental approaches is being used to perform kinetic measurements and
comprehensive catalyst characterization. Recent kinetic approaches have been focused on
transient techniques to examine the nature of reduction-oxidation mechanisms in reducible
molybdate and vanadate selective oxidation catalysts. In situ spectroscopic techniques, such as
laser Raman and Fourier transform infrared spectroscopies (FTIR) are emphasized since they can
be used to examine functioning catalysts. The goal of this research program is to provide
fundamental relationships between structure, composition, oxidation state, and surface properties
and catalytic activity and selectivity.
Ames Laboratory
Iowa State University
Ames, IA 50011
Molecular Processes Program
High-Temperature Gas-Phase Pyrolysis of Organic Compounds
The goal of this research is to understand in detail fundamental thermal reactions of organic
compounds, especially those related to the pyrolysis of coal and coal-derived liquids. Primary
products of thermal reactions are often highly reactive neutral species such as radicals, carbenes,
diradicals, and reactive molecules (i.e., species with no overall electronic charge, but with an
exceptionally reactive bond or group of bonds). Much of the work of this project focuses on
reactive molecules that are important in thermal reactions and includes development of novel
methods to prepare them and study of their spectroscopic and chemical properties. Studies have
concentrated on quinodimethanes, a large class of reactive molecules. The work with reactive
molecules has resulted in novel and effective ways of producing diradicals, and the reactions of
these intermediates are under study. Recently, several new thermal rearrangements of
hydrocarbons and related hetero-atom derivatives were discovered that fit a proposed two-step
mechanism that involves formation of a transient diradical by an intramolecular thermal
hydrogen-atom transfer. The results suggest that this two-step process is very general and may be
a major new way to account for rearrangements which occur when organic compounds are heated
to high temperatures.
Argonne National Laboratory
Argonne, IL 60439
Chemical Technology Division
Fluid Catalysis
| Investigator(s) |
Rathke, J.W.; Chen, M.J.; Klingler, R.J.
|
$695,000 |
| Phone | 630-252-4549 |
| E-mail |
rathke@CMT.anl.gov |
This program uses an array of in situ high-pressure spectroscopic and kinetic techniques to
explore the catalytic reaction chemistry of small molecules that serve as precursors in many
industrial processes. Precursors of interest include those of the C1 chemical
industry, e.g., CO, CO2, and CH4; the ammonia synthesis
precursors, H2 and N2; and the ceramic precursors, e.g.
(CH3)4Si and (CH3)3B. The
efficient utilization of these molecules is potentially of great economic significance; however, in
many cases the required conversion chemistry is difficult to achieve by present strategies. Recent
research of the Fluid Catalysis Program encompasses (1) in situ high-pressure NMR exploration
of phosphine-modified catalysts for the hydroformylation of olefins in supercritical fluids, (2) the
development of the toroid cavity imager, an R&D 100 Award winning MRI device, for the
investigation of ceramic precursor processes at elevated temperatures and pressures, and (3) the
study of extremely robust polyfluorophthalocyanine catalysts for hydrocarbon activation
processes.
Argonne National Laboratory
Argonne, IL 60439
Chemistry Division
Premium Coal Sample Program
This program provides uniform, well-preserved coals for fundamental coal science research. Eight
coals are available ranging in rank from a lignite to a low-volatile bituminous coal. These samples
have been sealed under nitrogen in glass ampoules. Over 23,000 samples have been distributed
worldwide. More than 900 shipments totaling over 23,500 ampoules have been shipped thus far.
A Users Handbook, including bibliographic information for published data generated from APCS
samples is updated periodically and is available on request (see contact below). This information is
also now available on-line via World Wide Web (http://www.anl.gov:80/PCS/pcshome.html).
Information is continuously added to these databases.
Argonne National Laboratory
Argonne, IL 60439
Chemistry Division
Characterization and Reactivity of Coals and Coal Macerals
| Investigator(s) |
Winans, R.E.; Anderson, K.B.; Dyrkacz, G.R.; Botto, R.E.; Carrado, K.A.
|
$1,954,000 |
| Phone | 630-252-7479 |
| E-mail |
rewinans@anl.gov |
The goal of this program is to provide a detailed view of coal structure ranging in scale from
microscopic to molecular. An objective is to be able to predict the reactivity of the Argonne
Premium Coals under a variety of conditions from models based on the fundamental information
derived from this program and other studies. The chemistry of large molecules is a major focus,
which has led to research on the synthesis and the characterization of large-pore, layered clay
catalysts for upgrading large complex organic molecules. The heterogeneous nature of coal
adversely influences its reactivity, and complicates processing technologies for the production of
usable, high-quality fuels and chemical feedstocks. To reduce heterogeneity, we have been
systematically studying physical methods for the separation of coal into its fundamental organic
constituents (macerals). Further, chemical modification methods are coupled with structural and
spectroscopic measurements, such as synchrotron X-ray spectroscopy and scattering, solid- state
NMR spectroscopy and imaging, laser desorption time-of-flight mass spectrometry,
high-resolution tandem mass spectrometry, and small angle neutron scattering, to probe coal
structure, in particular, the large molecular building blocks. For the first time, the synthesis of
clays has been followed by anomalous small angle X-ray scattering (ASAXS). To further advance
this and other elements of the program, we are building the next generation ASAXS instrument at
the ANL Advanced Photon Source. The different types of carbons in macerals have been imaged
using X-ray synchrotron microscopy. Pyrolysis high-resolution mass spectrometry results on
Argonne Premium Coals suggest that strong bonds may be responsible for holding the aromatic
clusters together. Finally, nitrogen-containing aromatic clusters appear to be larger than other
types of aromatic clusters found in coals of all ranks.
Argonne National Laboratory
Argonne, IL 60439
Chemistry Division
A facility at APS for Time Resolved/Anomalous Small Angle X-ray
Scattering: Applications in Condensed Matter Research
| Investigator(s) |
Winans, R.E., Thiyagarajan P.; Crawford, R.K.; Carrado, K.A.; Tiede, D.M.
|
$85,000 Operating
$315,000
Equipment |
| Phone | 630-252-7479 |
| E-mail |
rewinans@anl.gov |
The objective of this project is to construct an X-ray scattering instrument on the undulator
beamline of the Basic Energy Sciences Synchrotron Radiation Center (BESSRC) at the Advanced
Photon Source (APS) that will offer unprecedented opportunities for studying static and dynamic
atomic order in condensed phases and nanoscale materials. The high flux at the APS will enable
time-resolved structural studies on dynamic systems using techniques that require high energy
resolution of the probing X-rays and high counting statistics. Anomalous small angle X-ray
scattering, ASAXS, became possible only after the advent of synchrotron sources. The power of
ASAXS for structural resolution of materials in non-crystalline states has been demonstrated in
such diverse areas as biophysics and metallic alloys. The high brilliance of the X-rays from the
undulators at APS will, for the first time, enable the full potential of both the time-resolved and
anomalous scattering techniques to be realized in such areas as heterogeneous catalysis, ceramics,
metallic glasses, organometallics, and photochemical energy conversion. The proposed ASAXS
facility will offer new capabilities for measuring atomic order within macromolecular assemblies in
disordered media on a length scale of 6-6000 Å. This capability will offer opportunities to
resolve the structural basis for catalytic function. We will use this facility to conduct
groundbreaking experiments on the structure and fundamental chemistry of novel metal oxide
catalysts, macromolecular photochemical energy conversion assemblies, coal and carbons, and
phase separation in metallic alloys.
Brookhaven National Laboratory
Upton, L.I., NY 11973
Department of Applied Science
Metal Hydrides
| Investigator(s) |
Reilly, J.J.; Johnson, J.R.
|
$200,000 |
| Phone | 516-344-4502 |
| E-mail |
jreillys@bnl.gov |
Knowledge of the behavior and properties of hydrogen/metal systems is essential for the
successful implementation of many energy-related processes and applications. The prime concern
of this program is to increase that store of knowledge through the determination of their
thermodynamic, kinetic, and structural parameters. A particular goal is to relate all pertinent data
and hypotheses in order to develop a predictive capability regarding the behavior of a given
system. This capability permits the synthesis of compounds having optimum properties for
particular applications. Current areas of research are electrochemical characterization of
metal-hydrogen systems, preparation of corrosion-resistant and high-capacity metal hydride
electrodes, kinetics of the formation and decomposition of hydride phases and the characterization
of a new class of hydrogen bronzes prepared from complex oxides. This involves the use of
various tools and techniques including thermodynamic and electrochemical measurements, X-ray
diffraction, in situ X-ray absorption spectroscopy methods and electrochemical corrosion
measurements.
Brookhaven National Laboratory
Upton, L.I., NY 11973
Chemistry Department
Catalysis: Reactivity and Structure
| Investigator(s) |
Andrews, M.A.; Koetzle, T.F.; Bullock, R.M.; Hrbek, J.A.; Hanson, J.C.; Rodriguez,
J.A.
|
$1,838,000 |
| Phone | 516-344-4347 |
| E-mail |
catalyst@dynamics.chm.bnl.gov |
The goal of this program is to provide an improved understanding of chemical catalysis by
elucidating details of the fundamental properties of molecules, surfaces, and their reactions that
are critical to catalysis. Reactivity-structure correlations are a key aspect of these studies.
Complexities stemming from the inherent multi-component aspects of heterogeneous catalysis are
explored using both ultra-high-vacuum surface science investigations of well-defined model
systems, and powder diffraction and x-ray absorption studies of more "real-world"
systems. In the former, emphasis is placed on understanding the effects of catalyst modifiers at a
molecular level and on rationalizing the distinctive behaviors of bimetallic surfaces that simulate
important industrial bimetallic catalysts. X-ray and ultraviolet photoelectron spectroscopies at the
National Synchrotron Light Source (NSLS) are essential to this work. In the latter systems, some
of the first in situ, time-resolved studies of the formation and transformations of zeolitic materials,
supported metals, and metal oxides under catalytic reaction conditions are now possible using our
improved x-ray diffraction/absorption facility at the X7B beamline at the NSLS. Homogeneous
catalysis efforts in the group are centered around transition metal hydride complexes and
sustainable feedstocks. Reactivity studies of metal hydrides are designed to elucidate the factors
that determine the rates and mechanisms of M-H bond cleavage and associated atom transfer
reactions that are central to the participation of metal hydrides and molecular hydrogen complexes
in catalysis. Our understanding of hydride chemical reactivity and bonding is further enhanced by
the uniquely accurate structural data for these complexes obtainable from neutron diffraction
studies at the High Flux Beam Reactor (HFBR). The knowledge gained from these studies is
utilized to assist in the development of new types of catalytic reactions, especially those designed to
yield non-oxidative approaches to oxygenated organics from sustainable resources, such as
biomass and carbon dioxide. In this regard, novel aspects of metal-carbohydrate chemistry are
being explored, with a focus on selective complexation, reactivity studies, and catalytic
conversions.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Materials Science Division
Selective Conversion of Light Hydrocarbons to Chemicals and Fuels
| Investigator(s) |
Bell, A.T.; Bergman, R.G.; Frei, H.; Iglesia, E.; Tilley, T.D.
|
$150,000 |
| Phone | 510-642-1536 |
| E-mail |
Bell@Cchem.Berkeley.edu |
The U.S. chemical and fuel industries are major sources of industrial waste and significant
consumers of energy. Considerable savings in energy, carbon dioxide emissions, and feedstock
costs could be achieved by developing catalytic processes for the selective oxidative
dehydrogenation of alkanes to alkenes and the selective oxidation of alkanes directly to products
such as alcohols, ketones, epoxides, and carboxylic acids. Achieving these goals requires an
understanding of the of the relationships between the structure and composition of the catalyst
and its function. This project addresses two major areas. The first is understanding how to control
the oxidative dehydrogenation of methane and C2+ alkanes over both heterogeneous and
homogeneous catalysts. Selective oxidation of C2+ alkanes and alkenes is the theme of the second
area of activity. The synthesis of novel oxide nanoclusters within microporous and mesoporous
solids and of monomeric reducible cations at zeolitic exchange sites will be investigated, since
these exhibit unique reduction-oxidation and acidic properties that can be exploited to control the
availability and reactivity of oxygen. It is also planned to investigate the photo-oxidation of
alkanes and alkenes with NO2 under mild conditions (a process that uses NO as a
catalyst and O2 as terminal oxidant), in order to achieve high selectivity to
oxygenated products. Visible light-driven alkane oxidation by O2 in
cation-exchanged zeolites will be explored for the direct conversion to alcohols.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Chemical Sciences Division
High-Energy Oxidizers and Delocalized-Electron Solids
The aim of this work is the synthesis and characterization of new two-and-three dimensional
solids that may be useful in electrical energy storage. Fluorides are emphasized because fluorine is
highly electronegative, small, and lightweight; thus, high oxidation-state fluorides such as those of
cobalt, nickel, copper, or silver have high oxidizing potential and low formula weights. Emphasis
is placed on the thermodynamically unstable fluorides, which have sufficient kinetic stability to be
easily stored. Such fluorides are not only powerful oxidizers, but the metal center in each is
comparable in electronegativity to fluorine. It is probable, therefore, that some of the
thermodynamically unstable fluorides will be metallic or even superconducting (like some copper
oxide systems). Access to such fluorides is provided by salts of anions that are thermodynamically
stable (e.g., NiF62-). Kinetically stable, thermodynamically
unstable fluorides, as reagents, can probably substitute for anodic oxidation processes (Simons
process) for the preparation of fluorochemicals. Lithium cations in open-channel fluorides could
provide ionic conductors stable to oxidation. New synthetic routes also provide access to ordered
mixed rutile materials (e.g., MnNiF4). These should be ferrimagnets. Other
"rutile" systems such as MNF (isoelectronic with MO2) like
CrO2, could be metallic.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Chemical Sciences Division
Catalytic Conversion of C1 Compounds
The purpose of this program is to develop an understanding of the fundamental processes
involved in the catalytic conversion of C1compounds such as carbon monoxide,
carbon dioxide, methane, formaldehyde, and methanol to gaseous and liquid fuels. Attention is
focused on defining factors that limit catalyst activity, selectivity, and resistance to deactivation,
and the relationship between catalyst composition/structure and performance. In recent studies,
the hydrogenation of CO and CO2 has been investigated over both Rh and Cu. In
the case of Rh, in situ infrared observations show that CO2 adsorbs dissociatively,
and that the adsorbed CO undergoes hydrogenation via a pathway that is identical to that
followed during the hydrogenation of gas phase CO. In the case of Cu, only a small portion of the
CO2 adsorbs dissociatively. Infrared observations show that CO2
undergoes hydrogenation to form formate species which are then converted to methylenebisoxy,
formaldehyde, and methoxy species. Hydrogenation of the last of these species produces
methanol. Promotion of Cu with zirconia enhances the rate of methanol formation due to an
increase in the concentration of formate species. The activation of methane has also been
investigated over supported metals and metal oxides. Thermal decomposition of methane on Ru
produces CHx species which polymerize to form alkyl species.
13C NMR spectroscopy has revealed the structure of the adsorbed species.
Hydrogenation of the adsorbed species produces a hologous series of alkanes. The interactions of
methane with supported BaO2 and PdO have been investigated as well as part of
an effort to understand the elementary processes involved in methane coupling to form ethylene
and methane combustion, respectively. Raman spectroscopy has proven useful in revealing the
dynamics of oxide consumption and the formation of new catalyst phases.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Chemical Sciences Division
Transition Metal Catalyzed Conversion of CO, NO, H2, and Organic
Molecules to Fuels and Petrochemicals
The goals of this project are: (1) to develop new chemical reactions in which transition metals
interact and chemically transform organic materials, (2) to understand how these reactions work,
and (3) to apply this information to the development of new potentially useful chemical
transformations. Several years ago a major discovery on this project was the first
alkane-transition-metal C-H oxidative addition reaction (C-H activation). This involved the direct
reaction of C-H bonds with an iridium center in the +1 oxidation state (Ir(I)). More recently, a
series of Ir(III) C-H activating complexes has been discovered. Subsequent research has been
directed at examining the scope and mechanism of these C-H activation reactions and working
toward utilizing them in the conversion of alkanes to functionalized organic molecules. Recent
activities on this project include (1) use of liquefied xenon and krypton as inert solvents for C-H
activation; (2) design of experiments aimed at determining whether weak metal-noble gas and
metal-alkane complexes intervene as intermediates in these processes; (3) exploratory studies on
the extension of C-H activation methods to C-F activation; (4) improvement in the techniques
utilized for flash kinetic studies aimed at directly measuring the rates of reaction of coordinatively
unsaturated C-H activating intermediates with alkanes, and (5) utilizing the Ir(III) C-H activating
systems in the synthesis of new novel organometallic materials, such as carbene complexes.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Chemical Sciences Division
Chemical Routes to Tailored Oxide Networks Based on Molecular and Polymeric
Precursors
Advanced solid-state materials with useful properties increasingly involve intricate
three-dimensional networks, characterized by complex stoichiometries (e.g., in ceramic
superconductors such as
HgBa2Ca2Cu3O8+d) and/or
metastable architectures (e.g., in zeolites). New generations of materials will undoubtedly result
from chemically directed, low-temperature synthetic routes. Our approach involves use of
synthesis, coordination chemistry, and condensation reactions to build novel three-dimensional
networks. Primary targets have been oxide-based materials, which are built from tailored,
oxygen-rich precursor molecules. This project involves synthesis and characterization of candidate
precursor molecules, and then examination of chemical processes by which a metal oxide building
block can be transferred to a growing network. Initial directions are based on the finding that
metal complexes of the siloxide ligand OSi(OtBu)3 eliminate
isobutylene and water cleanly at remarkably low temperatures (100-200 °C) to form
MxSiyOz materials. For example,
M[OSi(OtBu)3]4 (M = Zr, Hf) complexes
undergo very clean conversions at about 100 °C to homogeneous
MO2·4SiO2 materials. The chemistry of this network
formation allows control over the growth of ZrO2 nanoparticles at higher
temperatures. Other precursors being examined include the Al/P oxide cluster
Al4(OiPr)8[O2P(OtBu)2]4 and the
[ZnO2Si(OtBu)2]
polymer. The low temperatures at
which such conversions take place allow for the formation of networks in refluxing hydrocarbons,
thereby offering an alternative to the sol-gel approach to thin films, porous ceramics, fibers, etc.
(which usually employs alcohol solvents). Initial experiments also indicate that thermolyses of
precursor molecules in the crystalline solid state can generate surprisingly ordered microstructures
for the resulting oxide materials. Such observations are followed with attempts to add
directionality to the network formation, via added templates or "ancillary" ligands in
the precursor that might orient the condensation reactions. The ultimate goal of this research is to
provide tailored materials with new and specific structural, electronic, optical, and/or catalytic
properties.
Lawrence Berkeley National Laboratory
University of California
Berkeley, CA 94720
Chemical Sciences Division
Potentially Catalytic and Conducting Polyorganometallics
This project utilizes the principal investigator's expertise in synthetic organic methodology and
organometallic reaction mechanisms in an interdisciplinary approach to the designed construction
of polymetallic arrays, anchored rigidly on novel ligands that enforce hitherto unprecedented metallic topologies. It has provided
access to a range of new soluble organotransition-metal clusters with great potential as catalysts
for known and new organic transformations and as building blocks for novel electronic materials.
Recent advances include: (1) the discovery of a rapid synthetic entry into "star"
oligocyclopentadienylmetals, containing novel ligands in which a cyclic system is completely substituted along its periphery by cyclopentadienyl
units; (2) the development of improved regioselective coupling strategies on route to
permetallated linear ter- and quatercyclopentadienyls; and (3) the use of electron-reservoir
sandwiches [FeCp(arene)] as efficient and selective electrocatalysts for the synthesis of fulvalene
homo- and heterodimetallic zwitterions.
Lawrence Livermore National Laboratory
University of California
Livermore, CA 94550
Physics and Space Technology Department
Plasma-Assisted Catalytic Decomposition of NOx
| Investigator(s) |
Penetrante, B.M.; Hair, L.M.; Vogtlin, G.E.
|
$150,000 |
| Phone | 510-423-9745 |
| E-mail |
penetrante1@llnl.gov |
Plasma-assisted heterogeneous catalysis is an innovative technique for improving the reduction of
nitrogen oxides (NOx) under conditions that normally make it difficult for known
catalysts to function with high activity and durability. The goals of this project are to (1) explore
the effects of a plasma on the NOx reduction activity and temperature operating
window of various catalytic materials, and (2) develop a fundamental mechanistic understanding
of the interaction between the gaseous-phase plasma chemistry and the heterogeneous chemistry
on catalyst surfaces. Chemical kinetics models based on elementary reaction rate parameters are
being developed to describe the mechanisms in the plasma, on the surface, and at the
plasma-surface interface where excited molecules, radicals, ions and electrons interact with
adsorbates on the catalyst surface. Experimental validation of the chemical kinetics is performed
using an existing state-of-the-art test facility. This facility includes a plasma/catalyst reactor that
can easily be modified to accommodate a wide variety of electrode and catalyst support
configurations, a set of chemical diagnostics for quantifying the concentrations of species in the
gas and on the surface, an electrical power conditioning unit, and a set of electrical diagnostics for
quantifying the energy consumption of the deNOx reactor. The temperature in the
reactor can be maintained at up to 600°C, and may be upgraded to accommodate higher
temperatures if necessary. Studies are being performed using nonzeolitic and zeolitic catalysts, as
well as novel metal oxide aerogel catalysts. Plasma-assisted catalytic schemes based on direct
NOx decomposition and selective catalytic reduction are being explored.
Los Alamos National Laboratory
University of California
Los Alamos, NM 87545
Chemical Science and Technology Division
Transition Metal Mediated Reactions of SO2, H2, and Other
Small Molecules
| Investigator(s) |
Kubas, G.J.; Burns, C.J.
|
$376,000 |
| Phone | 505-667-5767 |
| E-mail |
kubas@lanl.gov |
The binding and activation of environmentally and energy-related small molecules, particularly
H2, SO2 and halocarbons, by transition metal complexes is the
main thrust. Synthesis, structural characterization, and delineation of the reactivity patterns of a
wide variety of such molecules on 16-electron Group 6, 7, and 10 complexes such as
Mo(CO)(diphosphine)2 are being carried out. Goals include characterizing
metal-dihydrogen and related sigma-bond complexes (e.g. metal-silane), and mapping out and
comparing the reaction coordinates for cleavage of H-H and Si-H bonds on metal complexes. This
oxidative addition process is critical to catalysis and many types of chemical/biochemical
conversions. A new unsaturated cationic
complex, [Mn(CO)(dppe)2]+, was found to contain two agostic
phenyl C-H interactions and reversibly bind H2 and N2. We will
vary the ligand sets and large noncoordinating anion to better define H2 activation
on this highly electrophilic fragment and also synthesize new types of Mn agostic complexes such
as [Mn(CO)3(PR3)2]+. A
cationic Pt(II) system [PtH(P-i-Pr3)2L]+ was
prepared by protonation of Pt(P-i-Pr3)2(SO2)
and found to bind weak ligands, L, including H2 and halocarbons
(dichloromethane, bromobenzene). These will be further investigated. Early transition metal
sulfides such as [CpTiS(µ-S)]22- will be examined for
SO2 activation, and reduction of SO2 by hydride complexes will
be studied.
National Renewable Energy Laboratory
Golden, CO 80401
Basic Sciences Division
Basic Research in Synthesis and Catalysis
| Investigator(s) |
DuBois, D.L.; Curtis, C.J.
|
$461,000 |
| Phone | 303-384-6171 |
| E-mail |
DuBois@nrel.gov |
The major objectives of research carried out by the Synthesis and Catalysis Group are the
development of catalysts for electrochemical reduction of carbon dioxide, and the synthesis and
characterization of organometallic precursors for preparing semiconductor particles and thin films.
Electrochemical reduction of CO2 to methanol would provide an attractive route
for converting electricity to a liquid fuel with high energy density. The successful development of
efficient and stable catalysts for these reactions could have a major impact on the development
and use of renewable energy. Current efforts to increase catalytic rates involve the design of
catalysts capable of binding carbon dioxide at multiple sites. Studies of catalyst decomposition
products are being used to develop catalysts with longer lifetimes. The preparation of more
efficient and lower cost semiconductor materials would have a significant impact on the cost and
performance of solar cells and other devices. Current research efforts in this area are focusing on
the development of new precursors to thin films and semiconductor nanocrystals. This research
involves the synthesis and characterization of new organometallic complexes and nanoparticle
precursors and the study of their transformation to thin films.
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Chemical Technology Division
Kinetics of Enzyme-Catalyzed Processes
| Investigator(s) |
Greenbaum, E.; Woodward, J.
|
$530,000 |
| Phone | 423-574-6835 |
| E-mail |
greenbaume@ornl.gov |
The objective of this program is the study of fundamental kinetics and enzyme catalysis of
chloroplast reducing power related to fuels and chemicals production from renewable inorganic
resources. Fundamental studies that probe the function of the cellulase enzyme components in
relation to their structure are also being performed. Kinetic and mechanistic aspects of
photosynthesis will be studied using a unique experimental approach. Areas of investigation
include: (1) simultaneous light-driven production of hydrogen and oxygen; (2) separation of the
two light reactions of photosynthesis; (3) construction of photosynthetic photoelectrochemical
cells; (4) precipitation of metallic catalysts on photosynthetic membranes. Sustained
photoassimilation of atmospheric CO2 and simultaneous photoevolution of
molecular hydrogen and oxygen as well as photoautotrophic growth has been observed in
Photosystem I deficient mutants B4 and F8, of Chlamydomonas reinhardtii. Absence of
Photosystem I was demonstrated by P700 differential absorption spectroscopy. The sensitivity of
the technique permits a threshold detection limit of 3-5%. Even if Photosystem I were present at
that level, it would still be insufficient to account for the observed rates of photosynthesis. It is
concluded that Photosystem II is capable of performing complete photosynthesis. These results
may account for the origin and development of photosynthesis in the Earth's primordial
atmosphere. The interaction between catalytically active and inactive Trichoderma reesei cellulase
components and cotton fibers has been examined by scanning electron microscopy(SEM) and
atomic force microscopy(AFM). Cellobiohydrolase I (CBH I), the major component, was
rendered catalytically inactive by its treatment with ammonium hexachloropalladate; however, the
inactive enzyme still had the ability to bind to cotton fibers.
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Chemical and Analytical Sciences Division
Organic Chemistry and the Chemistry of Fossil Fuels
| Investigator(s) |
Buchanan, A.C.; Britt, P.F.; Hagaman, E.W.
|
$995,000 |
| Phone | 423-576-2168 |
| E-mail |
nan@ornl.gov |
The objective of this program is to conduct basic research that provides new knowledge on the
chemical structure and reactivity of fossil and renewable resources such as coal, lignin, and
biomass. The knowledge gained from this research will contribute to the scientific foundations
required for the future development of novel commercial processes for the conversion of these
complex, organic materials into chemicals or fuels in an environmentally responsible manner.
Solid-state NMR methods are being developed for the structural analysis of chemically modified
coals and lignins, which also can be applied to the analysis of other complex organic solids such as
derivatized charcoals, graphites, and polymers. Current research is focusing on high resolution,
solid state 19F-NMR and triple resonance techniques that utilize the
13C-19F dipolar interaction to provide local structure information
in fluorinated organics. Reaction chemistry for the selective fluorination of organic functional
groups is also under development. Reaction kinetics and mechanisms that underpin thermal and
catalyzed reactions of coal and lignin are being investigated through the use of fluid-phase,
silica-immobilized, and polymeric organic model compounds. Key issues currently being
addressed include the influence of heteroatoms on pyrolysis mechanisms, impact of restricted
mass transport on reactions involving free-radical and carbocation intermediates, and elucidation
of reaction pathways associated with retrogressive reactions in coal processing and with the
clay-catalyzed maturation of lignin. Thermolysis of oxygen-containing functional groups prevalent
in low rank coals and lignin such as carboxylic acids, ethers, and phenols are a current focus, and
research on flash pyrolysis mechanisms for biomass model compounds has been initiated.
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Chemical and Analytical Sciences Division
Basic Aqueous Chemistry at High Temperatures and Pressures
| Investigator(s) |
Mesmer, R.E.; Palmer, D.A.; Ho, P.C.; Simonson, J.M.; Gruszkiewicz, M.S.
|
$695,000 |
| Phone | 423-574-4958 |
| E-mail |
mesmerre@ornl.gov |
The purpose of this program is the experimental study of aqueous chemistry of broad classes of
solutes at high temperatures and pressures to establish basic principles governing chemical
equilibria and the thermodynamic properties of electrolytes. The advancement of both
experimental methods and new models for representation and prediction of behavior over wide
extremes of temperature and pressure are important parts of the program. A number of
complimentary techniques are used up to and beyond the critical temperature of water and its
solutions. Current research uses: flow calorimetry, densimetry, isopiestic apparatus,
electrochemical cells, electrical conductance apparatus, vapor-liquid partitioning cells, and Raman
spectroscopy. Chemical equilibria under study are ionization-ion association, metal complexation,
metal ion hydrolysis, solubilities, volatilities, and adsorption reactions. Reaction thermodynamic
quantities and excess properties of electrolytes are of interest. New results are bridging the
troublesome transition from strong to weak electrolyte behavior, and reaction behavior of new
classes of ions and species. Models are being developed for describing variations of both standard
state and excess thermodynamics quantities over wide ranges to temperature and pressure.
Computer simulations to relate macroscopic observations to microscopic structure have been
initiated. Initial work addresses ion pairing in the near critical region. Results impact strongly the
communities in basic solution chemistry and hydrothermal geochemistry, steam generator
technology, geothermal technology, environmental chemistry, and nuclear and hazardous waste
disposal.
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Chemical and Analytical Sciences Division
Heterogeneous Catalysis Related to Energy Systems
| Investigator(s) |
Overbury, S.H.; Huntley, D.R.; Mullins, D.R.; Grimm, F.A.
|
$610,000 |
| Phone | 423-574-5040 |
| E-mail |
OVERBURYSH@ORNL.GOV |
The objective of this program is to develop a fundamental understanding of catalytic reactions at
surfaces. Two areas of catalysis have been emphasized, hydrodesulfurization catalysis and
emission control catalysis. Previously, reactions and mechanisms for desulfurization of
organosulfur molecules and the relationship of these reactions to surface structure were studied.
Increasingly the emphasis is shifting to studies of interactions between reactive metals and
reducible metal oxides in catalytic reduction of NO and oxidation of CO and small hydrocarbons.
A major theme is to analyze synergisms between the metal and the support as related to the
adsorption state, reactions rates and mechanisms. The approach is experimental and is based upon
the use of surface analytical techniques to identify and monitor surface adsorbate species and their
effects upon the substrate vs reaction conditions. Techniques include alkali ion scattering and
electron diffraction for surface structure determination, temperature programmed desorption for
analysis of gaseous reaction products, soft x-ray photoemission using synchrotron radiation, and
high resolution electron energy loss spectroscopy for analysis of adsorbates. Equipment in
development will interface a catalytic reactor with vacuum surface characterization. Substrates
have included clean and modified single crystal metallic and bi-metallic surfaces, and in the future
will include metals (Rh, Pt, Cu) supported on oxide surfaces.
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Chemical and Analytical Sciences Division
Photolytic Transformations of Hazardous Organics in Multiphase Media
| Investigator(s) |
Sigman, M.E.; Dabestani, R.T.
|
$373,000 |
| Phone | 423-576-2173 |
| E-mail |
sigmanme@ornl.gov |
The objective of this program is to conduct fundamental investigations into the influence of local
chemical-environment on the mechanisms of photochemical transformation and destruction of
hazardous organics. Studies of photochemical events at interfaces (solid/liquid and solid/gas) and
in aqueous media are the primary focus of this research. Product analysis and in situ spectroscopic
techniques are the principal methods used in the investigations. Results from the studies
conducted in this laboratory are enhancing our basic understanding of photochemical processes
occurring at industrially and environmentally important interfaces and in aqueous solutions.
Surface morphology, strength of substrate/surface interactions, and surface acidity are among the
factors that control the interfacial photochemistry. The photochemistry of polycyclic aromatic
hydrocarbons (PAHs) has been the focal point of these studies because of the connection between
these materials and fossil fuel production and consumption and the status of many PAHs as EPA
priority pollutants. Highly polar surfaces, such as those of silicas and aluminas, have been shown
to have dramatic effects on the photochemistry of weakly interacting organics, as typified by
unsubstituted PAHs. Contributions from electron transfer and singlet molecular oxygen mediated
PAH oxidation pathways have been elucidated. The extent to which each of these two oxidation
mechanisms is operative is a function of PAH structure. Likewise, water has been shown to be a
medium that exerts significant influence on the rates and product distributions observed for PAH
photochemistry. Among other benefits to be derived from this research is a better understanding
of those factors that control the environmental fate and residence times of PAHs and related
anthropogenic materials.
Pacific Northwest National Laboratory
Richland, WA 99352
Chemical Sciences Department
Free-Radical Chemistry of Coal
| Investigator(s) |
Franz, J.A.; Alnajjar, M.S.; Autrey, T.; Linehan, J.C.; Camaioni, D.M.
|
$664,000 |
| Phone | 509-375-2967 |
| E-mail |
ja_franz@pnl.gov |
This project develops kinetic, thermochemical, and theoretical information describing the potential
energy surfaces of reactions of organic and organometallic free radicals, particularly those
involving sulfur, nitrogen, and oxygen important to coal, hydrocarbon and lignin chemistry.
Hydrogen transfer and bond scission pathways are examined in studies using kinetic EPR, laser
photoacoustic spectroscopy, CIDNP, and kinetic optical spectroscopic and product study
competition kinetics. Select bond strengths of heteroatom-containing organic hydrocarbons are
determined using redox thermochemical cycles and thermal decomposition studies. Advanced ab
initio calculations are employed to study novel hydrogen transfer and radical rearrangement
reactions. Mechanisms of reactions of nanometer FeS particles with organic substrates leading to
bond scission are investigated. High pressure liquid NMR is applied to study ligand and hydrogen
transfer reactions of organometallic hydrides and complexes. Triple-Resonance Solid NMR
techniques are developed for characterization of heteroatom structures in carbonaceous materials.
Pacific Northwest National Laboratory
Richland, WA 99352
Chemical Sciences Department
Theoretical Investigations of Heterogeneous Catalysis
| Investigator(s) |
Hess, A.C.; Nicholas, J.B.
|
$190,000 |
| Phone | 509-375-2052 |
| E-mail |
ac_hess@pnl.gov |
The purpose of this research program is to develop and apply atomic level molecular and solid
state theoretical methods to the study of catalytic processes occurring at the internal and external
surfaces of metal oxides and zeolites. These studies provide information on the geometric and
electronic structure of surface and surface adsorbate complexes including the energetics of
physisorption, chemisorption and dissociative chemisorption events. Particular emphasis is placed
on understanding the effect of topological and electronic defects, metal adatoms and explicit size
effects on the reactivity and selectivity of these materials. The complex geometric and electronic
structure of transition metal oxides and substituted zeolites combined with the need to accurately
predict the small energy changes associated with fundamental processes such as adsorption and
desorption is a challenging task for the current generation of theoretical methods. Our approach
to increasing the capabilities of solid state quantum mechanical methods that can efficiently
describe the ground state properties of these compounds is based on the mathematical
development of low order scaling methods that are designed to be implemented on large scale
parallel computing systems. To this end we have developed a new all electron periodic Gaussian
basis density functional approach that provides fully self-consistent solutions to the Kohn-Sham
equations for systems periodic in 3-(cyrstals), 2-(surfaces) and 1-(polymers) dimension. This new
method is implemented in the program GAPSS and is currently being used on large scale parallel
computers to study several metal oxide and transition metal oxide systems. These studies strive to
provide reliable information on quantities of importance which are difficult to obtain by
experimental means. The specific systems being investigated are generally chosen jointly with our
experimental collaborators to maximize the interplay between theory and experiment.
Pacific Northwest National Laboratory
Richland, WA 99352
Environmental Molecular Sciences Laboratory
Fundamental Studies of Oxygen Storage Materials: Transient Effects on NOx Reduction
Kinetics and the Role of Aging on These Material Properties
| Investigator(s) |
Peden, C.H.F.; Chambers, S.A.; Kay, B.D.
|
$150,000 |
| Phone | 509-375-5916 |
| E-mail |
ch_peden@pnl.gov |
The goal of this research is to fill a gap in the fundamental understanding of catalyst activity and
durability with respect to the transient NOx reduction performance in automotive
catalytic converters. Our overall objective is to obtain detailed chemical kinetics data on idealized
but well-characterized catalyst systems useful for understanding the important elementary
converter reactions. A particular focus of the work will be on how the catalytic chemistry is
effected by the oxygen uptake, storage, and release processes carried out by the oxygen storage
material. The fundamental understanding of critical rate-determining processes in this complex
system will provide insight into the material properties required for improved, more durable
catalysts. For example, we will elucidate and quantify the mechanisms responsible for the
improved performance with the use of ceria/zirconia mixtures relative to ceria alone formulations.
The kinetic data to be obtained in this program will also be used for the further development of a
full process model to describe the performance of an actual vehicle running the Federal Test
Procedure (FTP). Ultimately, this detailed understanding will lead to the ability to model both the
performance and durability of catalysts on actual vehicles. While this is a considerable challenge
and clearly a long-term (>10 year) goal, there are a number of recent developments that have
enabled considerable progress to be made in this area. This work is providing an excellent
opportunity to couple the powerful fundamental research capabilities of Pacific Northwest
National Laboratory with a currently ongoing applied research program at General Motors
Research Laboratories.
Last updated by Harry J. Dewey, (hd@lanl.gov) on December 16,
1996.