In situ preparation of CaTiO3 and its effect on CO2 sorption performance of nano-CaO-CaTiO3 adsorbent

The aim of this work is to prepare the nano-CaO-CaTiO₃ adsorbents with both high CO₂ sorption capacity and high durability. A series of nano-CaO-CaTiO₃ adsorbents with different CaTiO₃ grain sizes were in situ prepared by the reaction between TiO₂ and nano-CaO with variation of the preparation methods, doping contents and thermal pretreatment conditions. The results showed that the CaTiO₃ grain size would decrease by adopting the adsorption phase reaction method, reducing the doping content as well as thermal pretreatment temperature and time properly. Moreover, smaller CaTiO₃ grain size was favourable for increasing sorption capacity of the adsorbent, while larger CaTiO₃ grain size was more helpful for improving the durability. Under the consideration of the benefit of both the sorption capacity and the durability of adsorbents, the optimal CaTiO₃ grain size was got as 23.5 nm and its sorption capacity remained 8.52 mol/kg at the 50th cycle under the actual severe regeneration condition.

Advanced High-Temperature CO2 Sorbents with Improved Long-Term Cycling Stability

Developing novel sorbents with maximum carbonation efficiency and good cycling stability for CO₂ capture is a promising route to sequester anthropogenic CO₂. In this work, we have employed a green synthesis method to synthesize CaO-based sorbents suitably stabilized by MgO and supported by in situ generated carbon under inert atmosphere. The varied amounts (10-30 wt %) of MgO were used to stabilize the CaO. The supported mixed metal oxide (MMO) sorbents were screened for high-temperature CO₂ capture under CO₂ rich (86% CO₂) and lean (14% CO₂) gas streams at 650 °C and atmospheric pressure. The MMO sorbents captured 53-63 wt % of CO₂ per gram of sorbent under 86 and 14% CO₂, accounting for about 98% carbonation efficiency, which outperforms the CO₂ capture capacity of limestone derived CaO (L-CaO) sorbents (22.8 wt %). All of the synthetic MMO sorbents showed greater capture capacity and cyclic stability when compared to benchmark L-CaO. Because of the high carbonation efficiency and cycling stability of g-Ca_0.69Mg_0.3O sorbent, it was tested for 100 carbonation/regeneration cycles of 5 min each under CO₂ lean conditions. The g-Ca_0.69Mg_0.3O sorbent showed exceptional CO₂ capture capacity and cycling stability and retained about 65% of its initial capture capacity after 100 cycles.

Acquiring an effective CaO-based CO2 sorbent and achieving selective methanation of CO2

CO₂ capture, utilization, and storage are promising strategies to solving the problems of superfluous CO₂ or energy shortage. Here, mechanochemical reduction of CO₂ by a MgH₂/CaH₂ mixture was first performed, by which we achieve selective methanation of CO₂ and acquire an effective CaO-based CO₂ sorbent, simultaneously. The selectivity of methanation is near 100% and the yield of CH₄ reaches 30%. Four MgO and carbon-doped CaO-based CO₂ sorbents (MgO/CaO/C, MgO/2CaO/C, MgO/4CaO/C, and MgO/8CaO/C) were formed as solid products in these reactions. Among them, the MgO/4CaO/C sorbent shows high initial adsorption amount of 59.3 wt% and low average activity loss of 1.6% after 30 cycles. This work provides a novel, well-scalable, and sustainable approach to prepare an efficient inert additive-including CaO-based CO₂ sorbent and selectively convert CO₂ to CH₄ at the same time.

We achieve selective methanation of CO₂ and acquire an effective CaO-based CO₂ sorbent by reduction of CO₂ with a MgH₂/CaH₂ mixture.

CO2 capture by a novel CaO/MgO sorbent fabricated from industrial waste and dolomite under calcium looping conditions

A synthetic sorbent prepared from carbide slag and dolomite by combustion exhibits high CO₂ capture capacity, good cyclic stability and a porous microstructure.