Template Technique for Synthesis of CaO-based Sorbents
Emissions of large amounts of CO2 to the atmosphere, mostly as a by-product of burning
fossil fuels in man-made processes, are contributing to climate change. Among the options for
reducing greenhouse gas emissions there is CO2 capture from the large stationary sources. It
was proposed in many works to use calcium-based sorbents for effective CO2 capture from
gases at high temperatures. It is well known that textural properties drastically effects to
sorption/regeneration performance of sorbent during cycles under the conditions of CO2
capture process . Different methods involving direct thermal decomposition of the,
Ca-containing precursors, wet chemistry, sol-gel technique and flame pyrolysis, were applied
to modify porous structure of Ca-based sorbents. In mentioned cases porosity and pore size
distribution are regulated by chemical nature of precursors and conditions of experiment.
In parallel with interest growing to CaO-sorbents novel template approach started
emerging and developing. In general this technique consists of two steps: at first step the
template particles with definite shape and size are introduced to matrix media. After that
matrix material solidifies and template is deleted. Thus, template synthesis with nanocasting
is a direct technique for design materials with appropriate porosity and pore size distribution
We have used template approach to introduce additional porosity in CaO-based sorbents and
to arrange theirs pore size distribution. The effect of synthetized sorbents porous structure on
their sorption performance during repetitive carbonation/regeneration cycles was investigated.
The pore size distribution of prepaid sorbents drastically depends on the quantity and the
size of introduced template, but also on the sorbent preparation conditions. The introducing of
template significantly increases the rate both of sorbent carbonation and calcination reactions.
of sorbent with template for more than 1 order of magnitude in comparing with the pure
sample without template. In this way template approach seems to be a perspective technique
to prepare the CaO-based sorbents with better carbonation/calcination performance  it is
also a subsequent development and improvement of synthesis technique required.
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