Clean Fuels Research
A major focus of the CFC- group is placed on the catalytic conversion of coal synthesis gas to chemicals through the FISCHER-TROPSCH Process (FT). Moreover, the CFC-group is uniquely situated to focus on basic energy needs with a common goal to investigate and define scientific principles involved in catalysis as well as applying these scientific principles to the many uses of catalysts in industry.
Catalysis: An acceleration of the rate of a process or reaction, brought about by a catalyst, usually present in small managed quantities and unaffected at the end of the reaction. A catalyst permits reactions or processes to take place more effectively or under milder conditions than would otherwise be possible.
Nano-Catalysis: Nano-catalysis explores the basics of working with particles 1 billionth of a meter (atomic particle level) in size. "The nanoscale is where catalysts have been since before we understood why the size scale was unique" (Burt Davis). Individual particles of a substance have different physical properties creating a treasure of "new" catalyst materials with properties that can be radically different than those same atoms joined in their usual structures.
Catalysis seeks to develop materials and structures that exhibit novel properties that facilitate chemistry and significantly improve the control of chemical properties and functions due to their nanoscale. The economic contribution of catalysis is as remarkable as the phenomenon itself. Approximately one third of material gross national product in the US involves a catalytic process somewhere in the production chain. Total sales of catalysts in the US were more than $1 bn in 2000, with the catalyst market increasing about 5% per year.
Details about research and testing performed in the clean fuels and chemicals group are provided in the links below:
The Fischer Tropsch (FT) Process centers on the reaction of hydrogen with carbon monoxide, carbon dioxide or mixtures of these (FT synthesis) to yield one or more carbon compounds, e.g., hydrocarbons, alcohols, esters, acids, ketones, aldehydes, etc. The purification, separation, conversion or treatment of one or more of the products resulting from the Fischer-Tropsch synthesis, such as by oxidation, adsorption, solvent extraction, etc., is also of paramount importance.
Since its discovery in the 1920s, FT synthesis has undergone periods of rapid development and periods of inaction. A detailed overview of FT synthesis indicates that while the reactor development has been slow, the transition in FT-process developers has been very rapid. The CFC group under the guidance of Burt Davis which spans more than 20 years, has played a crucial role in balancing FT synthesis research and testing of significant data during industrial scale up.
The CFC group has attained a plateau that is probably the maximum that it should attempt to maintain at the experimental level. Using the third 3-Year contract from the U.S. Department of Energy, the testing facilities for FT catalysts was expanded to now include 23 continuous stirred tank reactors (CSTR). Eight of these reactors were utilized for DOE contract work and the other eight were used for catalyst testing for industrial organizations. The group also operates a small channel reactor.
Today these reactors are utilized for catalyst testing for companies and research under a contract with NASA. The testing for companies has two major impacts: (1) the discussions with the companies ensures that the CAER funded work is relevant to industrial needs and (2) it provides funding to bridge gaps between external contracts. Another important outcome of the company testing is that it documents the credibility of the work carried out the by the CFC group. In addition, the close contact with industry means that the results obtained by the CFC-group personnel will be utilized by companies who are likely to commercialize FC processes and in return, provide our personnel with the opportunity to learn various facets of the commercialization process during interactions with industrial personnel.
In addtion to the 16 CSTRs, the CFC group has modified and is now operating a two-inch inside diameter, six-foot tall slurry bubble column reactor (see picture). This reactor produces the same amount of product as can be produced in the 16 CSTRs, permitting us to provide sufficient sample material for a company to evalutate FT-products in a range of potential applications that they may wish to develop. The primary purpose of this reactor is to conduct attrition studies with iron catalysts, focused on developing a method to separate wax product from one micron-sized catalyst particles. A patent covers the use of the technique. Continued success with this technique will eliminate the need to develop robust iron catalysts since it will be possible to separate wax from a slurry containing particles as small as those produced by catalyst attrition. Finally, development of this capablility has led to a request for CAER to provide a cost estimate for catalyst testing using this equipment.
In summary, the work on FT can be viewed as a model where academic research leads to practical results that foster interactions with companies to provide significant funding the CAER.
One effort that is just starting again is a study in hydrocracking and isomerization processing. The CFC-group and a company jointly evaluate the catalytic conversion of FT wax to lower molecular weight products that are comprised primarily of iso-alkanes.
In the area of selective hydrogenation, the CFC group is conducting a small-scale study of the selective hydrogenation of acetylene in ethylene streams produced by naphtha cracking that is funded by Süd-Chemie Inc, an International Catalyst Producer the CFC-group has interacted with for more than 20 years. This particular interaction was instrumental for the CAER in obtaining the first DOE contract for FT synthesis.
The CAER has developed the capablitity to evalutate the adsorption capacity of mateirals and the CFC-group currently functions much as the control lab for Sud-Chemie Inc adsorbents. Thus, Sud-Chemie Inc provides samples that they manufacture to the Catalysis Center for evaluation to learn whether the preparation meets specifications prior to shipping the product to the customer.
The common cataysis-oriented goals are to understand and predict the properties of nanosized materials and control how they facilitate chemical reactivity. Another critically important issue deals with the manufacture of nanoscale components from the bottom up and, finally to integrate nanoscale components into macroscopic scale objects and catalysts for real-world uses.
Nanoenergy has a strong focus on nano-structured materials and examines critical issues facing developers and manufacturers of novel sub-micron scale materials and their integration into the rapidly growing energy devices markets (fuel reformers, fuel cells, photo-electrochemical cells) by trying to utilize novel materials in advanced energy storage and conversion devices.
Polymer electrolyte membrane fuel cells (PEM-FC) require H2 fuel of very high purity, since the noble metal catalysts in the fuel cell electrodes of the fuel cell are susceptible to chemisorptive poisoning by CO and sulfur. H2 can be produced from the gasification, steam reforming, partial oxidation, or autothermal reforming of a number of resources (e.g., natural gas, petroleum, coal, methanol, ethanol, bio-oils, and biomass). However, CO is a byproduct from these processes and must therefore be converted. This is typically carried out in fuel processor, with a series of staged water-gas shift reactors. Since the reaction is exothermic, CO conversion by water-gas shift is thermodynamically equilibrium-limited. Therefore, following a high temperature catalytic shift stage, where a fraction of the CO is converted, a low temperature shift stage is necessary to take advantage of the favorable thermodynamic equilibrium limit that exists at low temperature. However, since kinetics are slower at low temperatures, highly active low temperature shift catalysts are required to rapidly approach the equilibrium conversion level. For onboard reforming, the catalyst must also be very stable, resistant to startup / shutdown cycles, and be non-pyrophoric. CAER researchers are actively working with industrial partners and pursuing research on nanoscale bifunctional catalysts aimed at optimizing the synergy between a partially reducible oxide and a metal.
With manufacturing and research facilities in Louisville, Kentucky, Süd-Chemie, Inc. is a leading international supplier of catalysts and is keenly focused on the new hydrogen economy. Süd-Chemie has worked with CAER on state-of-the-art nanoscale water-gas-shift (WGS) catalysts for hydrogen reformers geared towards the transportation industry. Likewise, CAER researchers have provided valuable assistance to Honda Research Inc., USA (Columbus, Ohio) to characterize the role of that alkali promoters play in facilitating the low temperature shift reaction over nanoscale Pt-based catalysts. In addition to low temperature shift, CAER researchers are exploring methods of producing and converting chemical carriers of hydrogen, such as methanol and ethanol. These carriers represent flexible fuels which may be synthesized from syngas (e.g., derived from coal gasification or natural gas reforming), transported via truck or pipeline, and subsequently reformed at a point-of-use. Research into catalytic hydrogen production, whether carried out onboard or at a remote stationary site, is important to establish a hydrogen-based economy. Next generation reformers will utilize nanostructures for well-known catalytic materials, aimed at significantly enhancing the yields of CO-free hydrogen.