From waste to high value utilization of spent bleaching clay in synthesizing high-performance calcium-based sorbent for CO2 capture

Abstract

A novel calcium looping (CaL) process integrated with a spent bleaching clay (SBC) treatment is proposed whereby fuels and/or heat from regeneration of SBC provide supplemental energy for the calcination process; in addition, the regenerated SBC could be used to synthesize enhanced CaO-based sorbents. Composite samples were prepared with various doping ratios together with the regenerated SBC via a pelletization process. All pellets were subjected to thermogravimetic analysis (TGA) tests employing severe reaction conditions to determine the optimal doping ratios and regeneration method for the SBC-based sorbents. These results demonstrate that pellets containing combustible components showed higher CO 2 uptake, due to the improved pore structure, which was verified by N 2 adsorption measurements. The as-prepared sorbent "L-10PC" (90% CaO/10% pyrolytic SBC) achieved a final CO 2 uptake of 0.164 g(CO 2) g(calcined sorbent)-1 after 20 cycles, which was 67.3% higher than that of natural limestone particles. A new larnite (Ca 2 SiO 4) phase was detected by XRD analysis; however, the weak XRD peak associated with it indicated a low content of larnite in the pellets, which produced a smaller effect on performance compared to cement. A synergistic effect was achieved for a sample designated as "L-5PC-10CA" (85% CaO/5% pyrolytic SBC/10% cement), which resulted in the highest final uptake of 0.208 g(CO 2) g(calcined sorbent)-1. Considering the simplicity of the pyrolysis regeneration process and the excellent capture capability of pellets doped with pyrolytic SBC, the proposed system integrating CaL with SBC pyrolysis treatment appears to be promising for further development.

Synthesis of highly effective stabilized CaO sorbents via a sacrificial N-doped carbon nanosheet template

“…4 Alternative approaches involve developing intermediate-temperature and high-temperature sorbents, which can directly trap CO from hot flue gases, and thus reduce the cost of CO 2 capture to more commercially acceptable levels. 5 Numerous types of sorbents including hydrotalcites 6,7 , calcium oxides [8][9][10][11] , and ceramic materials [12][13][14][15] have been studied. Calcium oxides in the form of calcium looping (CL) technology are considered to be one of the most promising candidates among these materials owing to (i) abundant naturally occurring CaO precursors (e.g.…”

Self-activated, nanostructured composite for improved CaL-CLC technology

“…The calcium looping process (CaL) is one of the most promising CO 2 capture technology because it uses abundant and cheap CaO-based materials as sorbent precursors with a high theoretical sorption capacity (i.e., 0.786 g CO 2 per g CaO) [1][2][3]. This process exploits a reversible gas-solid reaction between CaO and CO 2 to form CaCO 3 , according to Eq.…”

A study of the synergistic effects of Mn/steam on CO2 capture performance of CaO by experiment and DFT calculation

“…(b) and (c), a shift to the highest binding energy of Ca 2p and O 1s in C‐Mn‐CaO was found, which was not observed in the original CaO. It means that it was easier for the Ca atom and O atom in C‐Mn‐CaO to give electrons to CO 2 than the original CaO, which assisted the fast formation of CO 3 . The doping of Mn in CaO was beneficial to the electron transport from CaO to CO 2 , which accelerated the carbonation rates of CaO.…”

“…Among the CO 2 emission‐reduction technologies, calcium looping technology, i.e. carbonation/calcination cycles of CaO, is regarded as one of the most promising technologies for large‐scale CO 2 capture owing to its low cost and the good opportunities for integrating it with coal‐fired power plants . Calcium looping technology involves a reversible reaction between CaO and CO 2 .…”