TECHNOLOGY
Jury Still Out on Adapting Western Processes for Eastern Shale Studies of processes used to process western oil shale reach conflicting conclusions, whereas some new retorting methods look good for both
j
National [ational Meeting Meeting
SiïLows Eastern oil shale is known to be different from western shale. Whether that means that the processes used for western shale are adaptable for processing eastern shale remains to be seen. However, one evaluation of five existing processes indicates that, generally, processing requirements for eastern shale are different, though processes for western shale do produce usable products, and the general retort chemistry is similar for both types of shale. Other, independent evaluations of particular processes, on the other hand, suggest that adaptation is less difficult than first suspected. And, there are also some new retorting processes that may be not only effective for eastern shale but improvements on those now in use in the West. The adaptability of five retorting processes now used for western shale has been evaluated by a group at Los Alamos National Laboratory. William J. Parkinson, a Los Alamos staff member, told the Division of Petroleum Chemistry that the five processes included HYTORT (Institute of Gas Technology), Paraho C-H (combination heated), Paraho D-H (direct heated), TOSCO II, and a shale-fired power plant.
The HYTORT process uses a 90 mole % hydrogen recycle and operates at a pressure of 500 psig to increase oil yield. Paraho C-H combines the shale heating and combustion in a single step. However, the process usually needs large quantities of oxygen and diluent gases to burn off residual carbon and quench combustion. TOSCO II discards a lot of residual carbon in the spent shale. Paraho D-H also discards a lot of residual carbon and requires postretort gas cleanup. The shalefired power plant was entirely simulated. The evaluation assumed a nominal production of 50,000 barrels per stream day and that all plants would be located near a mine where shale could be purchased at $4.00 per ton. Although there are clear indications of the relative performance from each process, there is also considerable uncertainty in some of the cost data available to the evaluators. Of particular note are discrepancies in the data on retort costs. In all cases, the cost of acid gas removal is high, and the same cleanup techniques are not appropriate to all. Parkinson says that gas cleanup costs for the Paraho D-H processes are unusually high because the process produces large amounts of low-Btu sour gas. One of the biggest differences between eastern and western shales
is the lower hydrogen-to-carbon ratio of eastern shale. This presents a greater hydrotreating effort to produce an oil acceptable to refiners. It is also the basis for much of the adaptability problems with western technology. The general conclusions reached by Parkinson and his associates were that western shale retorting processes are not adequate for use in the East, that the HYTORT process is the best of those evaluated, and that the Paraho C-H and TOSCO II processes can be greatly improved. A difference of opinion was registered by Michael J. Roberts, manager of oil shale operations at the Institute of Gas Technology. IGT designed the HYTORT process and recently has been doing adaptation studies for Hycrude Corp. funded by Phillips Petroleum Co. A series of small pilot studies at IGT show that oil yields can be increased up to 230% of the Fischer assay yield from New Albany shale, a type typical of the eastern shales. The yield is a direct function of the hydrogen partial pressure. The actual hydrogen pressure to be used will be an economic compromise between yield and pressure. The indications are that, with suitable design modifications, at least one existing process is adaptable to processing eastern shale. A new way to process shales, east-
HYTORT is best of processes evaluated on eastern shale Process
HYTORT (IGT) Paraho C-H TOSCO II Paraho D-H Power plant
Product cost ($ per bbl)
Total capital ($ millions)
Oil production (bbl per stream day)
Operating cost ($ millions)
$ 48 70 75 106 107
$2188 2220 2240 3140 577
58,575 34,740 36,620 29,220 7,277
$428 391 390 428 50
By-produ< income ($ million!
$
63 160 69 221 None
April 23, 1984 C&EN
25
Technology ern and western, may be the molten salt bath. Although emphasis will probably be on producing a substitute crude oil for further refining into conventional products, the possibility exists that other products also may issue from molten salt reactors. One type of salt bath has been under investigation by a group at Los Alamos National Laboratory and was described by Cheryl K. RoferDePoorter. She noted that all the processes currently under consideration involve high-temperature pyrolysis and all have similar problems—namely, they require the handling of a lot of solids, they don't recover a lot of the available carbon in the shale, and they produce only a substitute crude oil that requires considerable refinery upgrading. Molten salt baths generally operate at lower temperatures than retorts and thereby reduce some of the problems. A lengthy search produced a candidate molten salt with the formula lNaOH:lKOH:0.5LiOH. Several samples of oil shale, subbituminous coal, wood sawdust, and tar sand were processed in the molten salt bath at 200 °C. Samples also were treated without the molten salts. Processing with the hydroxide doubled condensate yield from the coal and tripled the yield from sawdust. In addition, the sawdust was converted almost entirely to water-soluble products. The effects of the hydroxide on the tar sand were negligible. Although the shales used in the molten salt experiments were all western shales, the investigators see no reason why eastern shales should not react similarly. The use of the molten salt reactor is also more generally applicable to most feeds, excepting tar sand. Why this should be so isn't known. A mechanism that is consistent with the observations has been suggested: oxidative attack on the kerogen to form carboxylic acid salts, followed by decarboxylation of the salts to hydrocarbons. Dissolution of mineral matter in the shale is a problem and appears to be temperature dependent. No sulfur or nitrogen appears in the products. • 26
April 23, 1984 C&EN
Cutting carbonyl group stabilizes weedkiller f
NNational E Meeting c
St Louis
It's hard to invent a good herbicide, let alone bring it to market. Evidence for that hypothesis was offered to the Division of Pesticide Chemistry by chemists from FMC Corp.'s agricultural chemical group at Princeton, N.J. The work that led to FMC's Command, a new broad-spectrum herbicide for pre-emergent weed control in soybeans, was the topic of four presentations. Command is the first commercial member of a new class of herbicides, the 3-isoxazolidinones. FMC chemists Marvin J. Konz, Jun H. Chang, Sayed A. Aly, James A. Kerschen, and John P. Kolsevich, together with research managers Kenneth Wilson and William A. Van Saun, have been involved in their development. Describing the work that led to the discovery of the new herbicides, Konz and Chang noted that related compounds, the isoxazolidinediones, have been of interest to pharmacologists because of their analgesic, local anesthetic, and anti-inflammatory properties. Although there had been no reports of herbicidal activity, such heterocyclic ring systems are i m p o r t a n t constituents of many herbicides. So FMC undertook a synthesis program to investigate the weed-control potential of the class, particularly the 2-aryl- and 2-phenylmethylisoxazolidinediones. Several compounds were synthesized; one of them, 2-[2-(chlorophenyl) methyl] -4,4- dimethylisoxazolidine-3,5-dione (given the code name FMC 55626), showed great promise in greenhouse experiments. Used as a pre-emergent herbicide, FMC 55626 caused weed seedlings to emerge bleached, rather than green, and the effect was severe enough to kill the weeds. Most crop plants, including cotton, corn, and wheat, couldn't tolerate the herbicide either. Soybeans, however, were unaffected. Later field tests brought bad news.
Germinating weed seedlings were bleached, just as in the greenhouse, but they rapidly outgrew the condition and survived. Weed control was minimal, even for sensitive species. This suggested that FMC 55626 was susceptible to microbial and chemical degradation leading to loss of herbicidal activity; tests showed that that was indeed the case. In particular, the compound rapidly decomposed under mildly basic conditions, as a result of a decarboxylation reaction. The original promise of FMC 55626 was so great, however, that Konz, Chang, Aly, Kerschen, and Kolsevich mounted a broad investigation of structure/activity relationship. The aim was to improve stability while retaining herbicidal activity. The project involved extensive structural variations of the heterocyclic ring and substituent variations on the aromatic ring. For example, experiments with isoxazolidinethiones and isoxazolin-3(2H)ones revealed much about the electronic and structural requirements for biological activity. The studies also indicated that the compounds work by affecting carotene and chlorophyll synthesis in susceptible plants. One of the questions that had arisen early in the study of FMC 55626 was how important were the two
Carbonyl group causes instability in compound ci N-CH,
^
//
FMC 55626 (susceptible to microbial and chemical degradation) CI
Tm'-\j FMC 57020 (stable under field conditions)
carbonyl groups to herbicidal activity. As it turned out, they weren't important. Accordingly, the FMC team decided to remove the "lactone" carbonyl group from FMC 55626. The idea was to increase the stability of the heterocyclic ring by releasing some of the ring strain, and thus to hinder the decarboxylation reaction. It worked. The resulting 3-isoxazolidinones—in contrast to the 3,5-isoxazolidinediones—were stable in the field as well as in the greenhouse, while retaining the herbicidal activity of the 3,5-diones. So far, the most effective of this new class of herbicides has been 2-[2(chlorophenyl) methyl]-4,4-dimethyl-3-isoxazolidinone (FMC 57020), which differs from FMC 55626 only
by the absence of the carbonyl group in the 5 position on the heterocyclic ring. The company proposes dimethazone as the common name for FMC 57020. FMC says the new herbicide controls a large number of annual grass and broadleaf weeds in soybeans, including several that are poorly or not at all controlled by existing soilactive soybean herbicides. Toxicology studies show it to have low toxicity to mammals, birds, and aquatic life forms. The firm is pursuing commercial development and will conduct widespread field testing this year under an experimental use permit. A l t h o u g h primarily for soybeans, FMC 57020 also is being considered for use on other crops, including tobacco and potatoes. D
Texaco developing melt catalysis systems
nology. John F. Knifton, supervisor of exploratory research for Texaco Chemicals, explained to the Division of Petroleum Chemistry that molten salts have good heat transfer properties, dissolve a wide range of materials and, generally, promote high reaction rates. The molten salt is also a good medium for those reactions that require constant renewal of a "reacting" surface. Molten salt catalysis already has been used in a number of industrial a p p l i c a t i o n s , such as p l a t i n u m catalyzed hydroformylation and hydrogenation of olefins, dienes, and trienes. Texaco has been extending this technology by the direct synthesis of Ci to C3 alcohols and acetate esters from syngas. A variety of alcohol-ester combinations can be obtained by judicious selection of catalyst components. The catalyst precursors have three elements. There is a r u t h e n i u m source for the principal catalyst, and a second metal from a group including halogen-free titanium, zirconium, cobalt, manganese and rhenium compounds. Finally there is a low-melting (below 150 °C) quaternary p h o s p h o n i u m salt, such as tetrabutylphosphonium bromide, which forms the reaction medium. Ethanol predominates in the products from catalysis by rutheniumtitanium alkoxide combinations, with up to 61% being that substance. Ruthenium-cobalt catalysts yield a
^iational Meeting
Stl^uis Texaco Chemicals is developing a new method of homogeneous catalysis for making basic organic chemicals from synthesis gas. The method utilizes a reaction medium composed of bimetallic catalysts in a molten salt. One of the products is ethylene glycol. Homogeneous catalysis by metals is inherently selective and reproducible, and usually exhibits good yields. One problem, however, is that of recycling the catalysts. Several methods have been used to improve the recycle. In one approach transition-metal catalysts are immobilized by bonding them to functionalized organic polymers or inorganic supports. Another method uses phase-transfer catalysis, where catalyst and products eventually wind up in different phases in the reaction medium. A third method restrains catalysts with semipermeable membranes. A lesser-used method is the molten salt medium, and Texaco has been investigating this approach in developing its Ci processing tech-
more balanced mixture of Q to C3 alcohols. With ruthenium and halogen-free rhenium or manganese compounds, methanol is the dominant product. Addition of certain solvents to the medium also affects the product mix. Ethyl acetate, for example, dominates the product mix when p-dioxane is added. A ruthenium-cobalt system has been selected by Texaco for more intensive study of mechanisms. The specific catalyst is triruthenium dodecacarbonyl-dicobalt octacarbonyl couple dispersed in tetrabutylphosphonium bromide. Among other things, Knifton and his associates have defined the experimental limits of this catalytic system and have demonstrated catalyst recycle with it. Results so far indicate that the predominant initial reaction is methanol formation. Homologation to C2 to C3 alcohol becomes increasingly important with time. There is a corresponding reduction in the methanol content of the system. Acetate ester formation is slower than alcohol formation, but the original methyl ester appears to be converted to h i g h e r esters via some sort of homologation. Under the conditions used with the study, acetic acid is present only in trace amounts. Most of the ruthenium-cobalt present in the melt catalyst appears to exist as separate and identifiable metal carbonyl anionic entities. Mixed metal clusters, if present at all, are not present in high concentrations. Another, commercially valuable, product that can be made with the melt catalysts is ethylene glycol. Glycol preparation has been achieved with several catalysts, including rhodium, ruthenium, and cobalt. However, says Knifton, the usual systems still require rather severe conditions and often have slow reaction rates. He suggests that an improved glycol synthesis might be possible with melt catalysts of the mixed metal variety. He has investigated this possibility by preparing ethylene glycol and its monoalkyl derivatives from synthesis gas using mixed ruthenium-rhodium catalysts dispersed in a quaternary phosphonium salt such as tetrabutylphosphonium iodide, which is particularly productive. The catalyst was circulated several times without loss April 23, 1984 C&EN
27
Technology Molten salt method uses bimetallic catalyst CO/H 2
M-H
H20
C3H7OH
ROH
M = Metal (catalyst)
of activity. Methanol and ethanol are the principal by-products. Glycol production by this method is very sensitive to the applied partial pressure of carbon monoxide and hydrogen. The preferred carbon monoxide partial pressure is about 170 atm. Satisfactory yields
of glycol have been obtained from an equimolar synthesis gas at about 300 atm pressure. The synthesis is believed to be homogeneous since hydrocarbons higher than methane are rarely detected and the product distribution does not appear to vary with catalyst recycling. •
Renewed emphasis on energy research urged
trum is oil prices. Schriesheim notes that existing advanced technologies provide energy at two to three times the price of conventional energy. The same can be said for existing end-use technologies, such as photovoltaics, biomass conversion, and the like. The more exotic energy technologies, such as fusion and magnetohydrodynamics, have yet to be proved feasible. Schriesheim believes that only through radical improvements can any of the presently considered energy technologies hope to achieve costs low enough to be competitive with conventional energy. The only way that can happen is by sharply improved R&D in the basic studies that underlie these technologies. Cooperation of industry is essential to this goal, Schriesheim maintains, because the central task of bringing new technology into the marketplace can be done well only by industry. The oil embargo of 1973 was not a total surprise as is sometimes suggested. However, its most devastating effect was. That effect was the dramatic increase in oil prices.
National Meeting
SLIOUIS The checkered history of energy R&D since the Arab oil embargo of 1973 has prompted a noted research administrator to call for more basic research. Alan Schriesheim, deputy senior director of Argonne National Laboratory, told the Division of Petroleum Chemistry that the main message from recent history is that government energy policy should be concentrated on basic research. The long-term need for new energy sources hasn't changed since before the e m b a r g o , Schriesheim points out, and the present stability in oil prices provides a grace period for development. The government, though, has no business trying to move technology into the market place. The key issue in the energy spec28
April 23, 1984 C&EN
Most informed opinion prior to the embargo predicted oil price decreases from the Organization of Petroleum Exporting Countries because of the competition that they deemed inherent in OPEC. This was obviously wrong, Schriesheim says. The energy policy that issued from the oil embargo was an attempt to purchase near-term energy technology through a massive investment program. The investment was to be in new conversion technologies, such as those for converting coal to gas. To some extent this may have been reasonable considering the prediction for very high energy demands foreseen at the time of the embargo. The lowest estimate Schriesheim was able to find was for an annual demand of 125 quadrillion (1015) Btu. Today the average projection is for 85 quads, a drop of 50% in 10 years. It isn't surprising there was a mad rush to improve supply technology, with the specter of an energy-hungry nation facing starvation in view. Another miscue was the idea that higher energy prices following the embargo would stimulate U.S. exploration and production. It simply didn't happen. One reason was that resources of oil are finite. If there were any new oil fields out there waiting to be discovered, they are still waiting today. When this was realized, federal e n e r g y policy shifted to conservation, with the rationale that it was cheaper to save a barrel of oil than to produce one. By 1976, a somewhat balanced policy between conservation and supply had been developed. The Iranian revolution of 1978 was a further shock that produced a sharp decline in energy use that persists today. In the Reagan Administration, the role of federal R&D is one of demonstrating the principles that underlie the new technologies. Industry is then supposed to carry the torch into the marketplace. In a sense, this represents a return to the policies that were in place before the embargo. Schriesheim thinks it is now clear why the federal energy policies of the 1970s failed to achieve their goals. The policies, he says, were based on highly inflated energy demand estimates. They didn't recog-
Geochemical Behavior of Disposed Radioactive Waste
He*' G.S. Barney and W.W. Schulz, Editors Rockwell Han ford Operations J.D. Navratll, Editor Rockwell International Rocky Flats Plant Examines the complex issue of radioactive waste disposal and the health hazards at underground waste sites. Assesses the chemical and physical behavior of wastes from the nuclear fuel cycle, from nuclear weapons testing, and from medical and research activities. Reports in a single source the most recent and significant findings in this controversial area and looks at important ongoing research. CONTENTS Sorption and Desorption Reactions with Interbed Materials • Reactions Between Tc and Fe-Containing Minerals • Radionuclide Sorption Mechanisms and Rates on Granitic Rock • Actinide and Technetium Sorption on Fe-Silicate and Dispersed Clay Colloids • Adsorption of Nuclides on Hydrous Oxides • High-Level Waste Components on Solubility and Sorption of Co. Sr, Np. Pu, Am • Hydrolysis of Am(lll) and Pu(IV) • Aging Effect on Solubility and Crystallinity of Np(IV) Hydrous Oxide • Geochemical Controls on Radionuclide Releases from Waste Repository in Basalt • Radionuclide-Humic Acid Interactions • Oxygen Consumption and Redox Conditions in Basalt • Monitoring and Control of Eh-pH Conditions in Hydrothermal Experiments • Cs-Feldspars Interaction • Interaction of Groundwater and Basalt Fissure Surfaces and Effect on Actinide Migration • Organics and Radionuclides Subsurfaces Migration • Uranium Mining Releases • Uranium Mobility and Roll-Front Deposits • Crystal Chemistry of ABO4 Compounds • Transformation Characteristics of LaVx Nbi -x O 4 Compounds • Stability of Tetravalent Actinides in Perovskites • « and (3' Decay in the Solid State • Effects of Water Flow Rates on Leaching • Borosilicate Glass-Containing Waste • Leach Resistance of Iodine Compounds • Nuclear Waste — View from Washington. D.C. Based on a symposium jointly sponsored by the Divisions of Nuclear Chemistry and Technology, Industrial and Engineering Chemistry, and Geochemistry of the American Chemical Society
ACS Symposium Series No. 246 424 pages (1984) Clothbound LC 84-3106 ISBN 0-8412-0827-1 US & Canada $79.95 Export $95.95 Order from: American Chemical Society Distribution Office Dept. 70 1155 Sixteenth St.. N.W. Washington, DC 20036 or CALL TOLL FREE 800-424-6747 and use your VISA, MasterCard, or American Express credit card.
Technology nize the technical difficulties of energy supply. Neither did they recognize the government's historical inability to succeed in the marketplace. Finally, the policies failed to attract a broad and united industrial following. The current R&D focus on base technology is a step in the right direction. Today, Schriesheim says, t h e pressing need for near-term energy supplies has abated, but in the longer run the picture has not changed. U.S. fuel supplies are severely limited and are running out fast. "We have a ticking time bomb on our hands," he says. It has been ticking for many years. Attempts have been made to develop new energy technologies to defuse the bomb. Some of the technologies have yet to be proved feasible, and all are more expensive to use than further exploitation of conventional supplies. Even so, the U.S. is faced with the cost of developing these technologies. The only way to avoid huge energy costs in the future is to make some radical improvements in supply and end-use technologies. That means new engineering and design based on better scientific understanding, in short, more basic R&D. Schriesheim says this will mean that the national laboratories and the academic research communities will have to increase their contributions. However, in the long run, the efforts of industry will be most important. No technology will succeed if it doesn't succeed in the marketplace. That means that industry will be the key element. The requirements of an energy policy for this scenario are not new, but, Schriesheim says, are more important than ever. There must be greater flexibility in the design and administration of research programs. Industry and the research communities should have greater control in setting research priorities and in allocating research funds. There should be more exchange and interaction of personnel between public and private research organizations. It must be made easier for industry to acquire patents and other proprietary rights. To Schriesheim, the present grace period in energy development is the obvious time to apply policies based on these ideas. D
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