Harold Kung - US grants

In this project, the energies of metal-oxygen bonds involved in reduction and reoxidation of an oxide are measured by calorimetry using a heat-flow calorimeter. Heats of reduction are measured for reduction by carbon monoxide or by hydrogen; this permits calculation of heats of formation for metal- oxygen bonds using the known heats of formation of small molecules, or, if necessary, the mesured heat of reoxidation. If surface hydroxyls are formed, their heats of formation can also be determined. Laser Raman spectroscopy, performed before and after the calorimetry, is used to identify and track the particular bonds made or broken in the calorimetric reactions. Initial experiments are on the highly dispersed phases of vanadia supported or gamma-alumina and anatase (titania). Data on the energies of metal-oxygen bonds are not available. Such data should be very useful for understanding the catalysis and surface chemistry of oxides, particularly selective catalytic oxidation reactions in which the surface is the proximate source of oxygen; the effort proposed is a formidable task. Selective oxidations are major elements in the production of a variety of commodity and specialty chemicals. Although catalytic behavior is the focus of this study, the results will also contribute to understanding semiconductor surfaces and insulating layers in electronic materials, and passivation an corrosion in structrual materials.

A differential scanning calorimeter with accessories is acquired. This will be used to measure heats of reduction and of reoxidation of metal-oxide catalysts. The initial systems to be studied will be based on vanadia or molybdena. The data from these studies, together with spectroscopic data from other studies, will be used to establish the energies of surface-oxygen bonds. This information, in turn, can be used to predict surface reactivity and catalytic behavior.

An instrument is being assembled that consists of a custom-made calorimeter with a response time of less than thirty seconds (compared with five minutes or so for commercial microcalorimeters) and capability for simultaneous investigation of the sample withattenuated total reflectance infrared spectroscopy. The rapidresponse time will permit determination of the heat of a process such as adsorption before subsequent slower processes obscure the measurement, while simultaneous infrared spectroscopy allows identification of the site of the process in cases where more than one possibility exists. Among systems to be studied with this new technique are nitric oxide on metal oxides or on metal zeolites and pyridine or ammonia on zeolites.

ABSTRACT Harold Kung Funds are provided to subsidize travel and subsistance for speakers, junior faculty, postdoctoral associates, and graduate students to attend the 1995 Gordon Research Conference on Catalysis to be held June 25-30, 1995, in New London, NH.

ABSTRACT Harold Kung A catalytic reaction system suitable for use in a synchrotron X-ray beam is constructed. The system is to be used by the duPont-Norhwestern-Dow collaboration access team at the Advanced Photon Source (APS) at Argonne National Laboratory. The reactor system is equipped with a gas chromatograph and a mass spectrometer, and is serviced by a gas manifold capable of handling up to eight gases by remote control. It is to be used for in situ studies of catalytic reactions and structural studies of catalysts and catalyst precursors including vanadium-phosphorus oxides, transition-metal-promoted rhodium, copper-zinc oxide, supported palladium, microporous redox systems, and zeolites. ***

ABSTRACT Harold Kung This is an investigation of the active sites in zeolite catalysts used for cracking of hydrocarbons. Strong Bronsted sites in steamed HY zeolites are isolated by poisoning with an amine such as pyridine and then blocking the unpoisoned (weaker) hydroxyl sites by silylation. Careful regeneration of the strong sites then allows them to be studied separately from the weaker sites. This is done using nuclear magnetic resonance, infrared spectroscopy, and microcalorimetry of adsorption of basic probe molecules. A separate set of experiments is designed to explore the effects of extraframework cations on catalytic activity and hydroxyl-group properties. Extraframework aluminum, gallium, or lanthanum ions are introduced into HZSM-5 by reacting the zeolite hydroxyl groups with the chloride or alkyl of the metal introduced in the gas phase. Subsequent hydrolysis gives dispersed extraframework species that can be characterized for structure, cation location, and catalytic activity. Hydrocarbon cracking is a crucial step in the production of gasoline from crude oil. Although it is well established that steaming of HY zeolite results in a very active cracking catalyst, the factors responsible for this remain mysterious. This study is an attempt to identify and to isolate those sites that are responsible for the catalytic activity and to study their interactions with extraframework matter in the zeolite matrix. This is a collaborative research effort between Northwestern University and Amoco Oil Company. ***

ABSTRACT CTS-9704272 Kung Support is provided to partially cover attendee travel expenses and organizational costs of the Fifteenth North American Meeting of the Catalysis Society, to be held on May 18-23, 1997, in Chicago, IL. The meeting is widely respected and well attended by academic and industrial researchers in catalysis of the US, North America and other parts of the World. It serves as a forum of discussion of the upcoming scientific and technological advances in the field, and has a strong educational function for young faculty and graduate students.

ABSTRACT Proposal Title: GOALI: A Fundamental Study of Hydrocarbon Cracking on Acidic Zeolites Proposal Number: CTS-9807333 Principal Investigators: Harold H. Kung, Jeffrey Miller and Randall Q. Snurr Institution: Northwestern University This GOALI proposal is a collaboration between Northwestern University (H. H. Kung and R. Q. Snurr) and Amoco Chemicals R&D (Jeffrey Miller). Its objective is the determination of the mechanisms responsible for the enhancement of catalytic cracking activity produced by the steam dealumination of HY zeolite. In the proposed model of catalytic cracking of alkanes, three reaction mechanisms are operative: monomolecular cracking involving a non-classical carbocation, bimolecular cracking involving hydride transfer and beta-scission, and oligomeric cracking involving alkylation, oligomerization, hydride transfer and beta-scission. While both the bimolecular and oligomeric cracking are strongly dependent on alkane partial pressure, the monomolecular cracking is strongly dependent on acidic strength, and the oligomeric cracking is diffusion limited. Experimentally, the dominant mechanism would be manifested in the product distribution, and could be controlled by the operating condition. Therefore, various possible causes of enhanced activity in dealuminated HY will be studied under conditions that correspond to a predetermined mechanism. The formation of new acid sites will be tested by means of the monomolecular cracking rate. The role of extra-framework Al will be determined by contrasting the rates of monomolecular and bimolecular-oligomeric cracking. The role of internal diffusion in mesopores and defects will be elucidated by contrasting monomolecular, bimolecular, and oligomeric rates. Also to be studied are the effects of selective poisoning of acid sites, e.g., Na; of zeolite type (Y, ZSM-5, ferrierite, mordenite); of adsorption heat contribution to apparent activation energy; of adsorption of reactant alkanes on the selectivity of c ompeting cracking reactions. The experimental adsorption study will be supported by theoretical calculations and simulations of binary adsorption isotherms.

INT-0080301
Harold Kung

This award supports the participation of 12 US scientists and engineers in a US-South Africa Workshop on Catalysis Research, scheduled for June 2000 in Pretoria, South Africa. The organizers are Harold H. Kung, Department of Chemical Engineering, Northwestern University, Neil Coville, Department of Chemistry, University of the Witwatersrand, Johannesburg, and Cyril O'Connor, Dean of Engineering and the Built Environment, University of Cape Town, South Africa. The workshop will focus on technical discussions in order to identify potential collaborative research projects. Participants from both countries will be drawn from academia, government, and industry. The three primary themes of the workshop are selective oxidation catalysis, zeolite synthesis and analysis, and supported metal catalysis.

Catalysis plays a central role in chemical manufacturing and energy conversion industries throughout the world. Catalysis has also found increasing applications to improve environmental quality. Although there are numerous ongoing collaborations between researchers in the United States and Europe and Japan, relatively few exist with Africa. The area of catalysis is particularly appropriate for US-South African collaboration. In some selected heterogeneous catalytic technologies, South Africa is a world leader. South Africa has the only industrial-scale Fischer-Tropsch process. Further collaborative activity among US and South African researchers is expected to result from this workshop. This award is supported jointly by the Division of International Programs and the Division of Chemical and Transport Systems.

Abstract


Proposal Title: US-South Africa Collaborative Research on Supported Gold Complexes and Nanoparticles: Synthesis, Characterization, and Catalysis
Proposal Number: CTS-0121619
Principal Investigator: Harold Kung
Institution: Northwestern University


The objective of this proposal is to develop a collaborative effort with investigators from South Africa to study several model reactions on gold nanoparticles. This research area was identified as a prime candidate for the joint investigation at the US-South Africa Workshop on Heterogeneous Catalysis held in Pretoria in June, 2000. The focus of the work is to elucidate the nature of the active sites and the effects of modifiers on these sites. A combination of organogold complexes and gold salts will be used to prepare catalysts containing clusters of controlled distributions of metallic gold atoms and gold ions. The performance of these catalysts in CO oxidation, propene oxidation, and acetylene hydrogenation will be tested and compared with results derived from a model. In-situ methods used to probe active sites include atomic-resolution microscopy, Mossbauer spectroscopy, and synchrotron radiation techniques. To foster collaboration among the seven investigators, the US faculty will invite several South African graduate students to spend one to two years in their laboratories, and US students will visit South Africa to perform research. The results of the research are expected to advance an understanding of the mechanisms of gold catalysis and to further opportunities for new applications of gold in industrial catalysis.

Funds obtained from this proposal will be used to acquire a 400 MHz NMR spectrometer equipped with the necessary accessories for conducting state-of-the-art solid state NMR materials characterization experiments. The accessories will include a double-resonance, magic angle spinning (MAS) probe, which is essential for many solid state NMR spectroscopic applications, as well as a single-resonance CRAMPS (Combined Rotation and Multiple Pulse Sequence) probe for solid state NMR spectroscopy of the 1H nucleus. This requested instrumentation will provide greatly improved solid state NMR spectroscopic capabilities for studying a wide range samples, hence advancing the interdisciplinary materials research being conducted in a broad range of departments at Northwestern University (NU). Research programs which would immediately benefit from incisive condensed matter NMR characterization capabilities include those studying novel transition metal reagents for organic synthesis, novel opto-electronically active solids for optical communications, data storage, and organic transistors, metal-organic frameworks for efficient energy storage and catalysis, silicon-based cage structures and nanocapsules having unusual architectures, graphene nanoplatelets and carbon nanorods for solid state electronics and high-strength materials, novel structural and barrier polymers, and solid state natural materials such as resins and gums from plant exudates. The more sensitive one- and two-dimensional solid state NMR spectroscopy at ambient and variable temperatures offered by this new instrument will significantly enable far more definitive structural characterization of these materials, leading to a more detailed understanding of their functionality. The ability to conduct these studies in-house with high throughput and rapid feedback will not only allow NU materials research to move forward more expeditiously, but will also provide a more complete educational experience for graduate students who will learn modern solid state NMR spectroscopic techniques in a hands-on manner while applying it to their own research. Additionally, advanced undergraduate courses in the Chemistry, Chemical Engineering, and Materials Science and Engineering programs at NU will introduce experiments with this instrumentation. These educational benefits will spread far beyond NU as graduate and undergraduate students move on to other positions.


Modern Nuclear Magnetic Resonance (NMR) spectroscopy is an extremely powerful technique for understanding the structure and function of solid materials. Funds from this proposal will be used to acquire a state-of-the-art spectrometer for use by a broad community of materials research scientists and their students at Northwestern University. Interdisciplinary research being conducted in many departments will benefit from the structural characterization capabilities offered by the proposed instrument and not currently available to us. The data from this instrument will lead to a better understanding of a wide range of solid state materials currently under study and which are important to the development of more selective, efficient, and environmentally friendly catalytic processes, new materials for energy storage, opto-electronic materials for high-speed communications, data storage, and printed transistors, and stronger, lighter weight structural materials. This requested instrument will also play a major role in educational programs for our graduate and undergraduate students.