Oxidation of cerium(III) phosphate in steam in the presence of lithium halides and its use in thermochemical water-splitting cycles

Journal Article · Tue Jul 01 00:00:00 EDT 1980 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic50209a072· OSTI ID:5114899

Bamberger, C E; Robinson, P R

Thermochemical cycles for water splitting employ thermal energy to drive a cyclic series of chemical reactions, the sum of which is just H/sub 2/O + thermal energy = H/sub 2/ + 1/2 O/sub 2/. It was shown previously that cerium (IV) oxide, CeO/sub 2/, reacts with alkali metal hydrogen phosphates - MH/sub 2/PO/sub 4/ or M/sub 2/HPO/sub 4/, where M = Li, Na, K - at > 600/sup 0/C to produce O/sub 2/(g), cerium(III) phosphate, CePO/sub 4/, and alkali metal orthophosphates, M/sub 3/PO/sub 4/. When M = Na or K, the double phosphate M/sub 3/Ce(PO/sub 4/)/sub 2/ forms from the CePO/sub 4/ and the M/sub 3/PO/sub 4/. In seeking ways to use these reactions in thermochemical cycles, it was discovered that steam will oxidize CePO/sub 4/ to CeO/sub 2/ in the presence of lithium halides - LiX, where X = Cl, Br, I - according to the following reaction: 2CePO/sub 4/(c) + 6LiX(c,l) + 4H/sub 2/O(g) = 2CeO/sub 2/(c) + 2LiPO/sub 4/(c) + 6HX(g) + H/sub 2/(g), (c), (l), and (g) refer respectively to the states crystalline, liquid, and gaseous. This paper describes studies of this reaction and its use in thermochemical cycles based on the Ce(IV)/Ce(III) redox couple.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5114899
• Journal Information: Inorg. Chem.; (United States), Vol. 19:7
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CERIUM PHOSPHATES
OXIDATION
HYDROGEN PRODUCTION
THERMOCHEMICAL PROCESSES
ACID PHOSPHATES
CERIUM OXIDES
HIGH TEMPERATURE
LITHIUM BROMIDES
LITHIUM CHLORIDES
LITHIUM COMPOUNDS
LITHIUM FLUORIDES
LITHIUM IODIDES
OXYGEN
STEAM
VERY HIGH TEMPERATURE
WATER
ALKALI METAL COMPOUNDS
BROMIDES
BROMINE COMPOUNDS
CERIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
LITHIUM HALIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORS
PHOSPHORUS COMPOUNDS
RARE EARTH COMPOUNDS
080102* - Hydrogen- Production- Thermochemical Processes
400201 - Chemical & Physicochemical Properties