Publications

Ethane oxidation reactions were studied over pure and Ca-, Mg-, Sr-, La-, Nd-, and Y-substituted BaCeO3 perovskites under oxygen limited conditions. Several of the materials, notably the Ca- and Y-substituted materials, show activity for complete oxidation of the hydrocarbon to CO2 at temperatures below 650 °C. At higher temperatures, the oxidative dehydrogenation (ODH) to ethylene becomes significant. Conversions and ethylene yields are enhanced by the perovskites above the thermal reaction in our system in some cases. The perovskite structure is not retained in the high temperature reaction environment. Rather, a mixture of carbonates and oxides is formed. Loss of the perovskite structure correlates with a loss of activity and selectivity to ethylene.

The depolymerization of organosolv-derived lignins by bases in methanol or ethanol solvent was studied in rapidly heated batch microreactors. The conversion of lignin to ether solubles by KOH in methanol or ethanol was rapid at 290 "C, reaching the maximum value within 10-15 minutes. An excess of base relative to Lignin monomer units was required for maximum conversion. Strong bases (KOH, NaOH, CSOH) convert more of the lignin to ether soluble material than do weaker bases LiOH, Ca(OH)2, and NacCO2). Ethanol and methanol are converted to acetic and formic acid respectively under the reaction conditions with an activation energy of approximately 50 kcal/mol. This results in a loss of solvent, but more importantly neutralizes the base catalyst, halting forward progress of the reaction.

Crystalline silicotitanates (CSTs) are a new class of ion exchangers that were jointly invented by researchers at Sandia National Laboratories and Texas A&M University. One particular CST, known as TAM-5, is remarkable for its ability to separate parts-per-million concentrations of cesium from highly alkaline solutions (pH> 14) containing high sodium concentrations (>5M). It is also highly effective for removing cesium from neutral and acidic solutions, and for removing strontium from basic and neutral solutions. Cesium isotopes are fission products that account for a large portion of the radioactivity in waste streams generated during weapons material production. Tests performed at numerous locations with early lab-scale TAM-5 samples established the material as a leading candidate for treating radioactive waste volumes such as those found at the Hanford site in Washington. Thus Sandia developed a Cooperative Research and Development Agreement (CRADA) partnership with UOP, a world leader in developing, commercializing, and supplying adsorbents and associated process technology to commercialize and further develop the material. CSTs are now commercially available from UOP in a powder (UOP IONSIV{reg_sign} IE-910 ion exchanger) and granular form suitable for column ion exchange operations (UOP IONSIV{reg_sign} IE-911 ion exchanger). These materials exhibit a high capacity for cesium in a wide variety of solutions of interest to the Department of Energy, and they are chemically, thermally, and radiation stable. They have performed well in tests at numerous sites with actual radioactive waste solutions, and are being demonstrated in the 100,000 liter Cesium Removal Demonstration taking place at Oak Ridge National Laboratory with Melton Valley Storage Tank waste. It has been estimated that applying CSTs to the Hanford cleanup alone will result in a savings of more than $300 million over baseline technologies.

In 1991, the Department of Energy initiated the Advanced Liquefaction Concepts Program to promote the development of new and emerging technology that has potential to reduce the cost of producing liquid fuels by direct coal liquefaction. Laboratory research performed by researchers at CAER, CONSOL, Sandia, and LDP Associates in Phase I is being developed further and tested at the bench scale at HTI. HTI Run ALC-1, conducted in the spring of 1996, was the first of four planned tests. In Run ALC-1, feed coal ash reduction (coal cleaning) by oil agglomeration, and recycle solvent quality improvement through dewaxing and hydrotreatment of the recycle distillate were evaluated. HTI`s bench liquefaction Run ALC-1 consisted of 25 days of operation. Major accomplishments were: 1) oil agglomeration reduced the ash content of Black Thunder Mine coal by 40%, from 5.5% to 3.3%; 2) excellent coal conversion of 98% was obtained with oil agglomerated coal, about 3% higher than the raw Black Thunder Mine coal, increasing the potential product yield by 2-3% on an MAF coal basis; 3) agglomerates were liquefied with no handling problems; 4) fresh catalyst make-up rate was decreased by 30%, with no apparent detrimental operating characteristics, both when agglomerates were fed and when raw coal was fed (with solvent dewaxing and hydrotreating); 5) recycle solvent treatment by dewaxing and hydrotreating was demonstrated, but steady-state operation was not achieved; and 6) there was some success in achieving extinction recycle of the heaviest liquid products. Performance data have not been finalized; they will be available for full evaluation in the new future.

A new class of inorganic ion exchangers called crystalline silicotitanates (CST), invented by researchers at Sandia National Laboratories and Texas A&M University, has been commercialized in a joint Sandia-UOP effort. The original developmental materials exhibited high selectivity for the ion exchange of cesium, strontium, and several other radionuclides from highly alkaline solutions containing molar concentrations of Na{sup +}. The materials also showed excellent chemical and radiation stability. Together, the high selectivity and stability of the CSTs made them excellent candidates for treatment of solutions such as the Hanford tank supernates and other DOE radwastes. Sandia National Laboratories and UOP have teamed under a Cooperative Research and Development Agreement (CRADA) to develop CSTs in the powdered form and in an engineered form suitable for column ion exchange use. A continuous-flow, column ion exchange process is expected to be used to remove Cs and other radionuclides from the Hanford supernatant. The powder material invented by the Sandia and Texas A&M team consists of submicron-size particles. It is not designed for column ion exchange but may be used in other applications.

The crystalline silico-titanates developed by the Department of Chemical Engineering at Texas A&M University, Sandia National Laboratories and UOP exhibits extremely high ion exchange selectivity for removing cesium from aqueous defense wastes. Based on experimental data and structure studies, a competitive ion exchange model was proposed to predict the ion exchange performance in different simulated waste solutions. The predicted distribution coefficients were within 10% of the experimentally determined values.

Sandia National Laboratories has worked with Synthetica Technologies and Manufacturing and Technology Conversion International (MTCl) to demonstrate the applicability of their commercial steam reforming technologies for treating DOE low-level mixed wastes. Previously, Synthetica successfully demonstrated destruction of a Sandia formulated lab trash simulant. During November 1994 Synthetica did not adequately process the aqueous halogenated organic liquid mixed waste simulant (MWTP-2110) formulated by the DOE Mixed Waste Integrated Program (MWIP). Testing at MTCl is ongoing and initial results appear to be favorable. Approximately 200 lbs each of the MWIP aqueous halogenated organic liquids (MWTP-2110), and absorbed aqueous and organic liquids (MWTP-3113/3114) simulants have been processed. At 1650{degree}F, destruction efficiencies of greater than 99% were obtained for tetrachloroethylene, toluene, and 1,2 dichlorobenzene. Product cases consisted primarily of H{sub 2}, C0{sub 2}, CO, and CH{sub 4} and had higher heating values of up to 355 BTU/SCF. Conclusions concerning the suitability of the MTCI process for treating DOE mixed wastes will be drawn upon the completion of testing.

This report describes work performed at Sandia under a CRADA with Shell Development of Houston, Texas aimed at developing hydrous metal oxide (HMO) catalysts for oxidation of hydrocarbons. Autoxidation as well as selective oxidation of 1-octene was studied in the presence of HMO catalysts based on known oxidation catalysts. The desired reactions were the conversion of olefin to epoxides, alcohols, and ketones, HMOs seem to inhibit autoxidation reactions, perhaps by reacting with peroxides or radicals. Attempts to use HMOs and metal loaded HMOs as epoxidation catalysts were unsuccessful, although their utility for this reaction was not entirely ruled out. Likewise, alcohol formation from olefins in the presence of HMO catalysts was not achieved. However, this work led to the discovery that acidified HMOs can lead to carbocation reactions of hydrocarbons such as cracking. An HMO catalyst containing Rh and Cu that promotes the reaction of {alpha}-olefins with oxygen to form methyl ketones was identified. Although the activity of the catalyst is relatively low and isomerization reactions of the olefin simultaneously occur, results indicate that these problems may be addressed by eliminating mass transfer limitations. Other suggestions for improving the catalyst are also made. 57 refs.

Sandia National Laboratories, as part of the Containment Integrity Programs under the sponsorship of the Nuclear Regulatory Commission (NRC), has developed analytical techniques for predicting the performance of light water reactor steel containment buildings subject to loads beyond the design basis. The analytical techniques are based on experience with large-scale steel containment model tests that provided important insights and experimental validation of the analytical methods. As a means of demonstrating these analytical techniques, the NRC asked Sandia to conduct a structural evaluation of an actual steel containment building. The objective of the analysis was to determine the actual pressure capacity and the mode, location, and size of failure, where a functional definition of failure is used. The purpose of this report is to document the calculations performed to determine the pressure limits for the shell- rupture mode of failure. General failure of the containment shell is predicted by application of a failure criterion to the results from finite element structural analyses. The failure criterion relates the calculated values of strain in the containment plates, due to internal-pressurization loading, to the ultimate strain limit of the steel. Included in the failure criterion are adjustments for factors inherent in finite element analysis, such as level of detail and element size of the finite element model and variations in material property data. Separate finite element models were used to evaluate the overall free-field behavior of the structure and the localized behavior at a specific penetration location. 18 refs., 68 figs., 10 tabs.