The Zr-Doped CaO CO2 Sorbent Fabricated by Wet High-Energy Milling

We fabricated the Zr-doped CaO sorbent for high-temperature CO2 capture by the wet high-energy co-milling of calcium carbonate and natural zirconium dioxide (baddeleyite) for the first time. The morphology of the material was examined by scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. Its CO2 uptake capacity was determined using thermogravimetric analysis. After 50 carbonation–calcination cycles, the Zr-doped CaO sorbent characterized by a high enough CO2 uptake capacity of 8.6 mmol/g and unchanged microstructure due to CaZrO3 nanoparticles uniformly distributed in the CaO matrix to prevent CaCO3 sintering under carbonation. The proposed easy-to-implement CaO-based sorbents fabrication technique is promising for industrial application

Electrospun Zr-Doped CaO Sorbent for CO₂ Capture

A Zr-doped CaO sorbent for high-temperature CO2 capture was fabricated using electrospinning. The nanofiber sorbent with an average filament diameter of about 160 nm is characterized by an initial CO2 uptake capacity of 12.1 mmol/g, a specific surface area of 79 m2/g, an indentation Young’s modulus of 520 MPa, and a hardness of 1.6 MPa. After 50 carbonation/decarbonation cycles, the sorbent has a decent CO2 uptake capacity of 9.7 mmol/g due to the uniform distribution of CaZrO3 in the CaO nanofibers to prevent CaO grain growth caused by CaCO3 sintering. It is revealed that the sorbent CO2 uptake capacity decreases both with an increase in the decarbonation temperature and with an increase in the CO2 concentration in the gas flow upon carbonation, where the sorbent CO2 uptake capacity is more sensitive to the decarbonation temperature than to the CO2 concentration in the gaseous stream during carbonation. It is assumed that the electrospun regenerable Zr-doped CaO sorbent is effective for removing CO2 from flue gases

The Nanofibrous CaO Sorbent for CO₂ Capture

The nanofibrous CaO sorbent for high-temperature CO2 capture was fabricated by the calcination of electrospun composite filaments containing calcium acetylacetonate and polyacrylonitrile as a calcium-oxide precursor and a binder polymer, respectively. The calcination was carried out in air to prevent PAN carbonization and to obtain pure CaO nanofibers. The resulting mats of CaO nanofibers with the average diameter of 130 nm were characterized by a specific surface area of 31 m2/g, a CO2-uptake capacity of 16.4 mmol/g at the carbonation temperature of 618 °C, a hardness of 1.87 MPa, and the indentation Young’s modulus of 786 MPa. The low decarbonation temperature makes the fabricated sorbent promising, for example, for the calcium-looping technology of CO2 removal from the hot exhaust gases of fossil-fueled power plants

Preparation of Zirconia Nanofibers by Electrospinning and Calcination with Zirconium Acetylacetonate as Precursor

For the first time, zirconia nanofibers with an average diameter of about 75 nm have been fabricated by calcination of electrospun zirconium acetylacetonate/polyacrylonitrile fibers in the range of 500–1100 °C. Composite and ceramic filaments have been characterized by scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption analysis, energy-dispersive X-ray spectroscopy, and X-ray diffractometry. The stages of the transition of zirconium acetylacetonate to zirconia have been revealed. It has been found out that a rise in calcination temperature from 500 to 1100 °C induces transformation of mesoporous tetragonal zirconia nanofibers with a high specific surface area (102.3 m2/g) to non-porous monoclinic zirconia nanofibers of almost the same diameter with a low value of specific surface area (8.3 m2/g). The tetragonal zirconia nanofibers with high specific surface area prepared at 500 °C can be considered, for instance, as promising supports for heterogeneous catalysts, enhancing their activity

Effect of Zirconia Nanofibers Structure Evolution on the Hardness and Young’s Modulus of Their Mats

Zirconia nanofiber mats containing filaments with the average diameter of less than 100 nm were fabricated. It is found that the hardness and Young’s modulus of the mats are sensitive to the microstructure, phase composition and average diameter of the zirconia nanofibers. The hardness and Young’s modulus of the prepared zirconia nanofiber mats vary from 0.86 to 1.67 MPa and from 133 to 362 MPa, respectively, wherein an increase in hardness is accompanied by the rise in Young’s modulus