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:

Silva, L J; Bray, L A; Frye, J G; Buehler, M F

Publication Date:

Tue Nov 01 00:00:00 EST 1994

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