2007 Awardee Ronald Pugmire, University of Utah
The ACS Division of Fuel Chemistry Henry H. Storch Award is given annually to an individual who has made outstanding contributions to research in the field of fuel science. Special consideration is given to innovation and novelty in the use of fuels, characterization of fuels, and advances in fuel chemistry that benefit the public welfare or the environment. These goals and attributes are strikingly manifested in the research and achievements of Dr. Ronald J. Pugmire, Professor of Chemical Engineering and Adjunct Professor of Chemistry at the University of Utah who is the 2007 recipient of the award sponsored by the Division and by Elsevier.
Pugmire’s research contributions in the field of nuclear magnetic resonance (NMR) spectroscopy and its application to fossil fuel characterization and utilization, as outlined below, and seen in more detail in the attached vita and publications, are characterized by creativity, originality, depth and breadth and major impact upon fuel chemistry.
Pugmire is internationally recognized for his contributions to the development of 13C, 1H, 15N NMR techniques to characterize both liquid and solid hydrocarbon fuels and their products. The body of the over 200 publications in the premier journals of the chemical and fuels communities to which he has contributed can be classified into the following six main areas as described below: I. Development of NMR techniques to characterize solid fossil fuels and fuel products; II. Characterization of the chemical structures of a large number of coals, including the seminal NMR work on the Argonne Premium Coals; III. Studies of coal maceral structure and techniques for separation and analysis of macerals; IV. Development of a structure-based coal devolatilization model; V. Characterization of model PAH compounds as precursors to aerosols and soot; and VI. Coal liquefaction.
I. Development of NMR techniques
Pugmire and his colleagues in the Utah NMR laboratory have developed experimental techniques to study a wide range of aromatic and polycyclic aromatic hydrocarbons. These experimental techniques include an analytical approach to the dipolar dephasing experiment, variable angle spinning, 2- and 3-dimensional solid-state experiments, such as PHORMAT, FIREMAT, and a solid-state hector experiment. The techniques developed by Pugmire and his colleagues have made NMR a critical analysis tool for understanding hydrocarbon chemistry, particularly in the solid state.
II. Characterization of the chemical structures of coals
Pugmire, as one of the members of the advisory panel to the Argonne Premium Coal Sample Bank established in the late 1980’s, assisted in the selection of the eight coals that are still available from ANL, as well as establishing the operation/management guidelines that contributed to the success of the premium coal sample storage and distribution program. Furthermore, he made major contributions to the characterization of the chemical structures of coals and coal products, such as chars and tars. His pioneering work on the 13C NMR cross polarization magic angle spinning (CP/MAS) experiments of the Argonne Premium Coals laid the groundwork for the study of dozens of other coals and coal macerals. The determination of the average aromatic cluster size (which relates to the average number of rings in a cluster) is unique to Pugmire’s research group, and has been invaluable in defining other structural features of coals. This technique allows one to estimate the average molecular weight per aromatic cluster, the average number of attachments per cluster, the average molecular weight of a side chain and the connectivity of the lattice structure. This latter factor is a key to the modeling of the coal lattice structure and the general conditions under which tar and light gas formation occurs in pyrolysis experiments. A number of major NMR experiments have been conducted on matching char-tar pairs as a function of the extent of pyrolysis. These data have provided an extensive amount of information on the changes in chemical structure that occur at different reaction temperatures. Experiments of this type were also employed to follow the changes in nitrogen forms by observing the 15N NMR signal.
III. Development of a structure-based coal devolatilization model
Pugmire was a key member of the team that developed the Chemical Percolation Devolatilization (CPD) model for coal pyrolysis. Pugmire’s NMR data that are incorporated into this model provide the definition of the moieties in coal and their linkages, including quantitative measures of the following groups: aldehyde and ketone; acid, ester and amide; protonated aromatic; phenolic oxygen bonded aromatic; alkyl group bonded aromatic; bridgehead aromatic; methyl; methylene and methyne; and oxygen bonded aliphatic. These were used to generate the parameters needed by CPD, such as the mole fraction of aromatic bridgehead carbons, the average number of attachments per cluster, the fraction of all possible bridges that are intact, the number of bridges and loops per cluster, the number of side chains per cluster, the average molecular weight of a cluster, and the average molecular weight of a side chain or half of a bridge. The resulting CPD model, widely used internationally, predicts the coal pyrolysis characteristics as a function of coal type, pressure, temperature, and heating rate, as well as the thermal behavior of other polymeric materials.
IV. Studies of coal maceral separation techniques and analysis of maceral structures
Pugmire’s early studies of coal maceral separation techniques and the structure of macerals was inspired by Peter Given, with whom he co-authored 4 papers. The maceral separation techniques employed were borrowed from the procedures developed at Argonne National Laboratory by personnel in the coal science group in the Chemistry Division (e.g., Gary Dyrkacz, et al.). For example, NMR structural data were obtained on 25 maceral concentrates from a total of 10 coals. The basic chemical structural characteristics of exinite/liptinite, vitrinite, and inertinite samples reported in this one paper represent the largest body of structural information available on maceral concentrates. Several other papers (a total of 12) provided additional data on maceral concentrates obtained from various U.S., British, and Australian coals.
V. Characterization of PAH and soot
Pugmire is now applying many of the NMR experimental techniques developed in his laboratory to the study of combustion aerosols and early soot formation. This work includes techniques similar to those used in the coal studies to follow chemical structure changes in the early stages of aerosol formation, including the formation and stabilization of free radical species in solid matrices via ESR data. This work is ongoing, with collaborations that include personnel at the University of Utah, University of Kentucky, Sandia National Laboratories and Argonne National Laboratory. Particularly interesting results from these studies are the differentiation of benzenoid and cyclopentafused rings that provides a measure of curvature of the soot precursors, the observation of a high free radical content of soot (up to 0.1% of the carbon atoms), and the measurement of the conductivity of the soot.
IV. Coal liquefaction
Early in his career, he worked with Professor Wendell Wiser, a former Storch Award recipient, on coal liquefaction. A valuable product from that collaboration is given in a 1979 paper in Fuel comparing the spectra of a solid coal with an artificially line broadened liquid spectrum obtained by catalytic hydrogenation. The resemblance was striking, indicating a strong relationship between many of the coal structural/functional groups and those that were present in the coal derived liquid. These data helped strengthen the arguments that liquefaction severed connecting covalent bonds and that many of the various functional groups in the solid and liquid product were similar. In 1985, a major collaboration, the Consortium for Fossil Fuel Liquefaction, was organized around research groups at the universities of Kentucky, Pittsburgh, West Virginia, Auburn, and Utah. Pugmire helped pull together this organization consisting of 15 different research groups. This consortium has been continuously supported for 20 years. Pugmire is now studying heterogeneous catalysts by investigating the nature of the ligand-metal interactions manifest in the C-13 chemical shift tensors of the carbon-metal bonds. As has been the case with all of the PAH studies carried out in the Utah laboratory, the correlation of theory and experiment is being pursued in order to understand the details of the bonding in the metal-ligand complexes. The end use of these experiments is a better understanding of the mechanisms that produce hydrogen from coal.
While Pugmire’s contributions span 40 years, we wish to note that his current research program has never been larger, with research activities covering 6 different projects in pyrolysis, heterogeneous catalysis, PAH’s as precursors to soot, and early stages of soot formation.
A further indication of Pugmire’s respect and standing in the fuels community is his many contributions to the Fuel Chemistry Division. He has been an active member of the ACS Fuel Chemistry Division, participating in many of the meetings, as well as the associated Gordon Conferences on Hydrocarbon Chemistry. In excess of 40 oral presentations have been made at the Fuel Chemistry Division meetings, International Conferences of Coal Science, and Gordon Research Conferences. He has been a member of the advisory panel of what is now the Gordon Research Conference on Hydrocarbon Resources for the past 10 years. He was responsible for development of the program, as Vice-Chair in 2003 and as Chair in 2005. The 2005 Conference was one of the most successful sessions of that conference in the recent past. Not only was the program pertinent to the issues facing the fuels community today, but it also included 41 student posters from participants in Australia, Japan, Korea, Turkey, Spain, and the U.S.
In summary, Pugmire is a preeminent fuels scientist with demonstrated excellence and accomplishments in the field. He is without doubt among the foremost contemporary experts in the characterization of coals and their products and the use of these significant and critical results to guide the development of improved methods of utilization of coal, both by direct combustion and through liquefaction. His seminal, highly creative and original research, as described above, has left an indelible mark on fuels chemistry and has had a major impact upon the field.