taBle 11.1
(Continued) Best two-, three-, and Four-step thermochemical Cycles
name/major
temperature
Compound
(°C)
details of Cycles
LASL-U/uranium
25
 
 
 
3CO 2 + U 3 O 8 + H 2 O → 3UO 2 CO 3 + H 2 (g)
250
 
3UO 2 CO 3 → 3CO 2 (g) + 3UO 3 1
700
6UO 3 (s) → 2U 3 O 8 (s) + O 2 (g)
Ispra Mark 2
100
 
Na 2 O.MnO 2 +  H 2 O → 2NaOH(a) + MnO 2
(1972)/Na/Mn
487
4MnO 2 (s) → 2Mn 2 O 3 (s) + O 2 (g)
800
 
 
Mn 2 O 3 + 4NaOH → 2Na 2 O.MnO 2 + H 2 (g) + H 2 O
Sulfur–Iodine/S/I
850
2H 2 SO 4 (g) → 2SO 2 (g) + 2H 2 O(g) + O 2 (g)
450
2HI → I 2 (g) + H 2 (g)
120
 
I 2 + SO 2 (a) + 2H 2 O → 2HI(a) + H 2 SO 4 (a)
Four-step Cycles
Vanadium
850
2Cl 2 (g) + 2H 2 O(g) → 4HCl(g) + O 2 (g)
chloride
25
 
 
2HCl + 2VCl 2 → 2VCl 3 + H 2 (g)
700
 
 
2VCl 3 → VCl 4 + VCl 2
25
 
2VCl 4 → Cl 2 (g) + 2VCl 3
Ispra Mark
850
2Cl 2 (g) + 2H 2 O(g) → 4HCl(g) + O 2 (g)
4/Fe/Cl
100
 
 
2FeCl 2 + 2HCl + S → 2FeCl 3 + H 2 S

420
 
2FeCl 3 → Cl 2 (g) + 2FeCl 2

800
H 2 S → S + H 2 (g)

Ispra Mark
850
2Cl 2 (g) + 2H 2 O(g) → 4HCl(g) + O 2 (g)
6/Cr/Cl
170
 
 
2CrCl 2 + 2HCl → 2CrCl 3 + H 2 (g)

700
 
 
 
2CrCl 3 + 2FeCl 2 → 2CrCl 2 + 2FeCl 3

420
 
2FeCl 3 → Cl 2 (g) + 2FeCl 2

Ispra Mark
100
 
 
 
2CuBr 2 + Ca(OH) 2 → 2CuO + 2CaBr 2 + H 2 O
1C/Cu/Ca/Br
900
4CuO(s) → 2Cu 2 O(s) + O 2 (g)

730
 
 
CaBr 2 + 2H 2 O → Ca(OH) 2 + 2HBr

100
 
Cu 2 O + 4HBr → 2CuBr 2 + H 2 (g) + H 2 O

UT-3 University
600
 
2Br 2 (g) + 2CaO → 2CaBr 2 + O 2 (g)
of Tokyo/Fe/
600
 
 
3FeBr 2 + 4H 2 O → Fe 3 O 4 + 6HBr + H 2 (g)
Ca/Br
750
 
CaBr 2 + H 2 O → CaO + 2HBr
300
 
 
 
Fe 3 O 4 + 8HBr → Br 2 + 3FeBr 2 + 4H 2 O
Source: Brown, L.C., Besenbrauch, G.E., Schultz, K.R., Showalter, S.K., Marshall, A.C., Pickard, P.S.,
and Funk, J.F., Spring National Meeting of AIChE, Nuclear Engineering Session THa01
139-Hydrogen Production and Nuclear Power, New Orleans, LA, (2002). With permission;
Schultz, K., Presentation to the Stanford Global Climate and Energy Project, General Atomics,
San Diego, CA (2003). With permission.
318
Water for Energy and Fuel Production