Compositional Effects of Nanocrystalline Lithium Zirconate on Its CO₂ Capture Properties

Abstract

A soft-chemistry route has been used for preparation of pure and promoted nanocrystalline lithium zirconate with different stoichiometries. The objective of this investigation has been to study the effect of different compositions on the acceptor and optimize the working properties of lithium zirconate. Special attention has been given to study the effect of different Li 2 O-ZrO 2 stoichiometries on the CO 2 capture rates. In addition, the partial substitution of Li 2 O with K 2 O as a promoter has been addressed. It has been found that both the capture rate and capacity of lithium zirconate depend considerably on the Li 2 O to ZrO 2 ratio. Enhanced capture rates are observed when a deficiency of Li 2 O is introduced. It is believed that the excess ZrO 2 might act as a dispersant and introduce more reactive boundaries. Moreover, the addition of K 2 O results also in improved capture rates due to the presence of molten carbonates, but lower capacities and poorer stability due to particle coarsening. The present of free ZrO 2 seems also beneficial for the stability of K 2 O-doped acceptors. Therefore, controlling the K:Li:Zr ratio has been found to be crucial for tailoring the properties of lithium zirconate. An optimized composition can result in an acceptor with enhanced capture rates, stability, and higher degree of utilization.

On the Influence and Role of Alkali Metals on Supported and Unsupported Activated Hydrotalcites for CO2 Sorption

“…27 Fernandez and co-workers showed that doping LiZrO 3 with K 2 CO 3 enhanced CO 2 absorption rates. 28 It was claimed that loading of potassium favors the diffusion of CO 2 through the LiCO 3 layer that is formed in the surface of the acceptor during the capture reaction. Our explanation for the increase in CO 2 capacity is based on the geometric rearrangement and defect surface structure of the various K-loaded HTs and is discussed below.…”

High temperature CO2 sorbents and their application for hydrogen production by sorption enhanced steam reforming process

“…In the case of K-Li 2 ZrO 3 , the formation of a eutectic molten carbonate layer of Li 2 CO 3 and K 2 CO 3 enhances the adsorption kinetic rate by increasing the CO 2 diffusion rate through the external layer. However, Ochoa-Fernandez et al [138] showed that despite the positive effect of potassium carbonate doping into Li 2 ZrO 3 on the kinetic rate of CO 2 adsorption, the CO 2 capture capacity and cyclic stability of sorbent was lowered by the addition of potassium. Figure 5.…”

CO2 Absorption Studies on Mixed Alkali Orthosilicates Containing Rare-Earth Second-Phase Additives

“…42−44 We anticipated that the rare-earth ceramic particles will act as a virtual shell against the segregation of absorbent phase, thereby impeding particle agglomeration and imparting absorbent powders with superior performance. 28) and fumed silica in the molar ratio 2.2:1. The powders were initially mixed with a pestle and mortar and then ball-milled for 24 h in isopropanol.…”