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Ammonia synthesis enhanced by magnesium chloride absorption
Author(s) -
Himstedt Heath H.,
Huberty Mark S.,
McCormick Alon V.,
Schmidt Lanny D.,
Cussler E. L.
Publication year - 2015
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.14733
Subject(s) - ammonia , chemistry , absorption (acoustics) , magnesium , ammonia production , diffusion , inert , catalysis , absorption efficiency , salt (chemistry) , inorganic chemistry , reaction rate constant , reaction rate , chloride , chemical engineering , thermodynamics , materials science , kinetics , organic chemistry , composite material , zoology , physics , quantum mechanics , biology , engineering
Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl 2 . The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl 2 salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl 2 than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J , 61: 1364–1371, 2015