(707e) Preparation and Absorption Behaviors Study of Doped Li4SiO4 At Low CO2 Concentration | AIChE

(707e) Preparation and Absorption Behaviors Study of Doped Li4SiO4 At Low CO2 Concentration


Qi, Z. - Presenter, East China University of Science and Technology
Sai, Z. - Presenter, East China University of Science and Technology

Preparation and Absorption
Behaviors Study of Doped Li4SiO4
at Low CO2 Concentration

Sai Zhang, Qi Zhang*,Qian Ye, Haiyan Wang, Zibin Zhu

Dept. of Chemical Engineering, East
China University
of Science and Technology, Shanghai 200237, China


K-doped Li4SiO4 samples were prepared to improve the pure
Li4SiO4 adsorbent's sorption/desorption properties in the
critical SESMR practical conditions with low CO2 partial pressure
and steam atmosphere. The optimized sample was analyzed by sorption experiments
and simulation with FactSage5.5 Software. The results show that the K-doped Li4SiO4
has a better CO2 absorption ability than pure Li4SiO4
as the K can form a eutectic compound with Li4SiO4 which
enhances the Li+ and O2- ions diffusion and thus
facilitating the CO2 absorption ability of Li4SiO4.
It is also found that steam not only enhances the Li+ mobility but
also reacts with Li4SiO4, therefore increase the mass
uptake of the adsorbent. In order to make the adsorbent more practical,
sorption-desorption cycle processes were also carried out. The results show
that the optimized Li4SiO4 has a lower desorption
temperature and stable absorption ability.

Furthermore, the
sorbents, Li4SiO4 and different K-doped Li4SiO4,
were evaluated using a bench scale unit, of which the results can provide
reference for the subsequent industrial design. Li4SiO4
and different K-doped Li4SiO4 were prepared by
solid-state reaction method. The results was obtained from the studies of
different Li4SiO4 samples in a fixed-bed reactor with
15%CO2 and 85%N2 at 575°æ.
The pure Li4SiO4 showed a short breakthrough time,
approximately 20 min, while modified Li4SiO4 samples
presented a relative 20~40 min longer breakthrough time under same conditions. The
results of the experiment indicate that doping K into Li4SiO4
can improve the adsorption capacity of the sorbents. Comparing with MgO-based K2CO3[1]
and hydrotalcites[2] sorbents, which breakthrough time are no more
than 40min and 13min, respectively, the relatively long breakthrough time of
K-doped Li4SiO4 exhibits huge potential for industrial applications.
K-Li4SiO4 with good performance at low CO2
partial pressure can be applied into sorption enhanced steam methane reforming
system, in which the CO2 concentration can be also as low as 15%. Meanwhile,
the regeneration period can be prolonged by doping appropriate amount K into
Li4SiO4, which means cost for recycling can be reduced as a result. K-doped
Li4SiO4 has a certain value in industrial application, both practicability and

Key words: CO2 acceptors, Lithium
orthosilicate, on-line absorption behaviors


[1]Soo Chool
Lee, Ho Jin Chae, et al. Development of Regenerable MgO-Based Sorbent Promoted
with K2CO3 for CO2 Capture at Low Temperatures[J]. Environ.Sci. Technol, 2008,
42: 2736-2741

[2]Hendricus Th.
J. Reijers, Sacha E. A.Valster-schiermeier, et al. Hydrotalcite as CO2 Sorbent
for Sorption-Enhanced Steam Reforming of Methane[J]. Ind. Eng. Chem. Res,
2006, 45, 2522-2530