Preparation and High-Temperature CO₂ Capture Properties of Nanocrystalline Na₂ZrO₃

Abstract

A novel method for producing nanosized Na2ZrO3 with well-controlled crystal phase has been developed, resulting in excellent kinetics for CO2 capture at high temperatures. The novel preparation method involves a soft-chemical route starting with the generation of a complex from zirconoxy nitrate and sodium citrate, followed by a strong exothermic reaction between nitrate and citrate during calcination in a controlled atmosphere. The in situ produced carbon during the calcination serves as a dispersant of the oxide, and subsequent carbon burnoff promotes the formation of nanocrystalline Na2ZrO3 with an open pore structure. The calcination temperature and atmosphere are very crucial for controlling the crystal phase of Na2ZrO3. The resulting sodium zirconate samples are characterized by XRD, N2 adsorption, Hg porosimetry, and SEM. A two-step calcination at 1073 K results mainly in the monoclinic phase, whereas one-step calcination at 1073 K or higher enhances the formation of the thermodynamically stable phase, namely hexagonal Na2ZrO3. A kinetic study of CO2 capture in a tapered element oscillating microbalance (TEOM) reactor has shown that the monoclinic Na2ZrO3 is much more active than its hexagonal counterpart. The ability to work at CO2 partial pressures as low as 0.025 bar, together with the excellent stability in multicycle capture/regeneration makes nanocrystalline Na2ZrO3 a very promising CO2 acceptor for different applications.

A first-principles density functional theory study of the electronic structural and thermodynamic properties of M2ZrO3 and M2CO3 (M = Na, K) and their capabilities for CO2 capture

“…III C. Experimental investigations showed that the alkali metal zirconates are good candidates of solid sorbents for CO 2 capture because they have large CO 2 sorption capacity, infinite CO 2 /N 2 or CO 2 /H 2 selectivity, good reversibility, and high operating temperatures. 8,[10][11][12]16 According to Eq. (4), the calculated heat of reaction (enthalpy change) for reactions of M 2 ZrO 3 þ CO 2 ¼ M 2 CO 3 þ ZrO 2 (M ¼ K, Na, Li) versus the temperatures is plotted in Fig.…”

“…Their results also indicated the regeneration performance of Na 2 ZrO 3 was not as good as Li 4 SiO 4 and Li 2 ZrO 3 . Zhao et al 16 investigated the kinetics of the CO 2 capture properties of nanocrystalline Na 2 ZrO 3 and found that monoclinic Na 2 ZrO 3 is much more active than its hexagonal counterpart. Their results showed that nanocrystalline Na 2 ZrO 3 is a very promising CO 2 acceptor for different applications due to its excellent stability and durability 17 and to be able to work at CO 2 partial pressure as low as 0.025 bar.…”

Effects of sodium precursors and gelling agents on CO2 sorption performance of sodium zirconate

“…[13] 5 mol% excess of sodium precursor was included together with stoichiometric amounts of Na and Zr precursors which was also listed in Table 1. This was to ensure complete conversion of the precursors into Na 2 ZrO 3 .…”

“…3.860 mmol/g at 575°C and P CO2 of 50 kPa by liquid-state synthesis. [13] However, modification of CO 2 solid sorbents by introducing other elements into the particle structure was known to improve their CO 2 adsorption performances. The Na 2 (Zr 1-x Al x )O 3 sorbent which was synthesised by Alcántar-Vázquez et al [22] had better CO 2 capture performance than pure Na 2 ZrO 3 at carbonation temperatures of T ≥ 500°C.…”

Catalytic Constructive Deoxygenation of Lignin-Derived phenols: New C–C Bond Formation Processes from Imidazole-Sulfonates and Ether Cleavage Reactions

“…Among the alkaline and/or alkaline-earth oxides, various lithium, sodium, potassium, calcium and magnesium ceramics have been proposed for CO 2 capture through adsorption and chemisorption processes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These materials can be classified into two large groups: dense and porous ceramics.…”