
12-1
12.1 Introduction
e demand for hydrogen as a process gas and as a renewable energy carrier to reduce dependence on
fossil fuels and to mitigate the problems associated with greenhouse gas emissions is increasing [1,2].
Hy
drogen
ha
s
a ve
ry
lo
w
de
nsity
(0.08
99
kg
/m
3
) and boiling point (20.39 K) and high diusion coef-
cient (0.61 cm
2
/s in air). It has a low minimum ignition energy (0.017 mJ), high heat of combustion
(1
42kJ/g
H
2
), and wide ammable range (4–75 vol% in air), as well as a high burning velocity and an
ig
nition
te
mperature
of 56
0
°C. Hy
drogen
al
so
ac
ts
as a st
rong
re
ducing
ag
ent
fo
r
ma
ny
el
ements
an
d
has a high permeability t ...