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Title: Spent catalyst processing with electrochemistry

Abstract

Increasing concern for pollution prevention and waste disposal has created a need for clean alternatives for spent catalyst processing. In addition, expanded use of catalysts for the production of fuels and chemical feedstocks will continue in response to (1) economic pressure to upgrade heavier crudes and other feeds having high levels of impurities; (2) competitive pressure to achieve higher conversions using less energy; and (3) pressure to increase reaction selectivities to minimize waste production. While the incentives for using catalysts are great, all catalysts gradually lose activity through coking; poisoning by metals, sulfur, or halides; or loss of surface area from sintering at high process temperatures. Regeneration is possible where the catalyst deactivation can easily be reversed. Electrochemical dissolution is a new technique to oxidize catalyst contaminants and dissolve catalyst metals in an aqueous solution for further recovery of the raw materials. The key to this process is adding spent catalyst to a solution containing small amounts of species that form kinetically active, strongly oxidizing ions such as cerium(IV) or silver(II). The oxidizing ions are regenerated at the anode; they act in a catalytic manner carrying electrons from the solid surface to the anode of the electrochemical cell. A ceriummore » oxidizer was used for the experiments described in this paper. For this procedure, solution is added to the anode side of an electrochemical cell. At the anode, aqueous cerium(III) is oxidized to cerium(IV). The cerium(IV), in turn, oxidizes organic material adhered to the catalyst to carbon dioxide and water. Many spent catalysts used in hydrogenations contain metal sulfides that have contaminated the catalyst surface during processing. Metal sulfides are oxidized to dissolved metal ions and sulfur species. Because cerium is continuously reoxidized to cerium(IV) at the anode, a small amount of cerium is needed to oxidize the spent catalyst.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest Lab., Richland, WA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10120083
Report Number(s):
PNL-SA-24795; CONF-941175-1
ON: DE95007270; TRN: 95:002134
DOE Contract Number:
AC06-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: 8. international forum on electrolysis in the chemical industry: environmental electrochemistry,Lake Buena Vista, FL (United States),13-17 Nov 1994; Other Information: PBD: Nov 1994
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CATALYSTS; MATERIALS RECOVERY; ELECTROCHEMISTRY; OXIDATION; RAW MATERIALS; CERIUM; OXIDIZERS; 320302; 400400; MATERIALS

Citation Formats

Silva, L.J., Bray, L.A., Frye, J.G., and Buehler, M.F.. Spent catalyst processing with electrochemistry. United States: N. p., 1994. Web.
Silva, L.J., Bray, L.A., Frye, J.G., & Buehler, M.F.. Spent catalyst processing with electrochemistry. United States.
Silva, L.J., Bray, L.A., Frye, J.G., and Buehler, M.F.. Tue . "Spent catalyst processing with electrochemistry". United States. doi:. https://www.osti.gov/servlets/purl/10120083.
@article{osti_10120083,
title = {Spent catalyst processing with electrochemistry},
author = {Silva, L.J. and Bray, L.A. and Frye, J.G. and Buehler, M.F.},
abstractNote = {Increasing concern for pollution prevention and waste disposal has created a need for clean alternatives for spent catalyst processing. In addition, expanded use of catalysts for the production of fuels and chemical feedstocks will continue in response to (1) economic pressure to upgrade heavier crudes and other feeds having high levels of impurities; (2) competitive pressure to achieve higher conversions using less energy; and (3) pressure to increase reaction selectivities to minimize waste production. While the incentives for using catalysts are great, all catalysts gradually lose activity through coking; poisoning by metals, sulfur, or halides; or loss of surface area from sintering at high process temperatures. Regeneration is possible where the catalyst deactivation can easily be reversed. Electrochemical dissolution is a new technique to oxidize catalyst contaminants and dissolve catalyst metals in an aqueous solution for further recovery of the raw materials. The key to this process is adding spent catalyst to a solution containing small amounts of species that form kinetically active, strongly oxidizing ions such as cerium(IV) or silver(II). The oxidizing ions are regenerated at the anode; they act in a catalytic manner carrying electrons from the solid surface to the anode of the electrochemical cell. A cerium oxidizer was used for the experiments described in this paper. For this procedure, solution is added to the anode side of an electrochemical cell. At the anode, aqueous cerium(III) is oxidized to cerium(IV). The cerium(IV), in turn, oxidizes organic material adhered to the catalyst to carbon dioxide and water. Many spent catalysts used in hydrogenations contain metal sulfides that have contaminated the catalyst surface during processing. Metal sulfides are oxidized to dissolved metal ions and sulfur species. Because cerium is continuously reoxidized to cerium(IV) at the anode, a small amount of cerium is needed to oxidize the spent catalyst.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 1994},
month = {Tue Nov 01 00:00:00 EST 1994}
}

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  • Increasing concern for pollution prevention and waste disposal has created a need for clean alternatives for spent catalyst processing. In addition, expanded use of catalysts for the production of fuels and chemical feedstocks will continue in response to (1) economic pressure to upgrade heavier crudes and other feeds having high levels of impurities, (2) competitive pressure to achieve higher conversions using less energy, and (3) pressure to increase reaction selectivities to minimize waste production. While the incentives for using catalysts are great, all catalysts gradually lose activity through coking; poisoning by metals, sulfur, or halides; or loss of surface areamore » from sintering at high process temperatures. Regeneration is possible where the catalyst deactivation can easily be reversed. However, the economic life of a catalyst is ultimately limited by regeneration costs and extent of irreversible deactivation.« less
  • During the past decades, detailed electrochemical analysis of many reactions of importance in mineral processing has provided a basis for the understanding and/or improvement of flotation separations, leaching processes, and cementation operations. The status of this electrochemical research activity is reviewed with examples from each system. Further advances are possible, and it is expected that spectroelectrochemical measurements and electrochemical AC impedance measurements will provide new dimensions to our understanding of these important electrochemical reactions. 59 refs., 15 figs., 5 tabs.
  • By combining electrochemical and electroless metal deposition processes with standard optical lithography and wet chemical etching, the authors have developed techniques for the fabrication of fine (<20 {mu}m), adherent, conducting features on poly(tetrafluoroethylene) (PTFE) substrates. These techniques are less expensive and have demonstrated resolution of at least a factor of five better than existing printed wiring board-based processes. Using these PTFE-based processes, the authors have fabricated {approximately} 10 GHz coupled-line quadrature (Lange) couplers, for which test results will be presented.
  • Irradiated nuclear fuel has been reprocessed at the Idaho Chemical Processing Plant (ICPP), which is a part of the Idaho National Engineering Laboratory (INEL), since 1953 to recover uranium-235 and krypton-85 for the US Department of Energy (DOE). The resulting acidic high-level liquid radioactive waste (HLLW) has been solidified to a high-level waste (HLW) calcine since 1963 and stored in stainless-steel bins enclosed in concrete vaults. Residual HLW and radioactive sodium-bearing waste are stored in stainless-steel underground tanks contained in concrete vaults. Several different types of unprocessed irradiated DOE-owned fuels are also stored at INEL. In April 1992, DOE announcedmore » that spent fuel would no longer be reprocessed to recover enriched uranium. As a result of the decision to curtail reprocessing the ICPP Spent Fuel and Waste Management Technology Development plan has been implemented to identify acceptable options for disposing of the (1) sodium-bearing liquid radioactive waste, (2) radioactive calcine, and (3) irradiated spent fuel stored at the INEL. The plan was developed jointly by DOE and Westinghouse Idaho Nuclear Company, Inc. (WINCO).« less
  • It has been demonstrated in batch and continuous bench-scale units that molten zinc chloride is a superior catalyst for liquefaction of coal, coal extract or other heavy hydrocarbons. High quality gasoline of 90 to 92 Research Octane Number is produced in high yield in a single hydrocracking step. Large amounts of zinc chloride are used as the catalyst for high activity, i.e., usually 1 gm of ZnCl/sub 2/ per gm of coal or extract feed. From 1 to 2 parts by weight of product catalyst is generated during the hydrocracking process depending on the ZnCl/sub 2//feed ratio. This product catalystmore » is contaminated with zinc sulfide, ammonia or ammonium chloride complexed with zinc chloride (formed by the catalyst partially reacting with the sulfur and nitrogen in the feed during the hydrocracking step), carbonaceous residue that cannot be distilled out of the melt, and coal ash, when coal is the feed to the hydrocracking process. To keep the catalyst active, these impurities must be removed in a regeneration process in which the catalyst is converted back to essentially pure zinc chloride. The regeneration is accomplished by burning out the impurities in a combustor containing a fluidized bed of inert silica sand. Hydrogen chloride gas is added to the feed air to convert ZnO to ZnCl/sub 2/ and to prevent formation of ZnO by hydrolysis of zinc chloride in the combustor. Continuous regeneration of this coal-ash-contaminated spent melt from direct hydrocracking of coal and efficient zinc recovery therefrom has now been demonstrated for the first time. In this work zinc recovery was enhanced by introducing a secondary zinc recovery step in which zinc, retained in the coal ash rejected in the primary regeneration step, is largely recovered. This paper presents some of the results of this regeneration work with natural spent melt from direct coal hydrocracking.« less