Lithium zirconate

Sorbents such as lithium silicate and lithium zirconate can absorb C02 at somewhat lower temperature of 500°C (Kato et al., 2002 Li et al., 2006),... 

Ding and Alpay also studied sorption-enhanced reforming with K-HTC as sorbent [28], using a commercial Ni-based catalyst. They found that the SER process benefits from higher pressures and that lower steam to methane ratios can be used than in ordinary reforming. Reijers et al. [25] have shown that K-HTC is an effective sorbent between 400 and 500 °C, with an C02 uptake of approx. 0.2 mmol g 1. This capacity is low compared with calcium oxides and lithium zirconates. Above 500 °C, the C02 sorption capacity of K-HTC decreases rapidly to zero [36]. 

Moving on to gas-solid reactions for CO2 capture, magnesium oxide can be rejected due to the lability of the corresponding carbonate and the greater stability of its hydroxide, while the old chestnut of calcium oxide requires temperatures in excess of 750 °C to regenerate the carbonate (Fig. 7.10). There are, nevertheless, other solid materials which can form carbonates in the temperature window of interest and be regenerated at lower temperatures of around 600 °C, for example lithium zirconate [38] which can theoretically adsorb 22.3 wt% CO2 ... 

Our own studies with lithium zirconate have demonstrated the critical importance of the ratio between the lithium salts and zirconia used in its preparation [21]. Further, it appears that the reaction is strongly inhibited by the superficial formation of solid products curtailing capacity and impairing kinetics to the point where characteristic adsorption times are measured in hours rather than the seconds necessary. Very slow rates of CO2 adsorption can also be observed in the early published data on lithium zirconate and, while some progress has been made [39], developing a... 

Properties White powder. A strong flux in enamels, glazes, and porcelains. It can be used in place of lithium zirconate. 

Nakagawa, K. Ohashi, T. A reversible change between lithium zirconate and zirconia in molten carbonate. Electrochemistry 1999,67 (6), 618-621. 

H. Kawamura, T. Yamaguchi, B. N. Nair, K. Nakagawa and S. Nakao, Dual-ion conducting lithium zirconate-based membranes for high temperature CO2 separation, J. Chem. Eng. Jpn., 2005, 38, 322-328. 

Absorption is a process that relies on a solvent s chemical affinity with a solute to dissolve preferably one species into another. It is widely proposed for CO2 separation where a solvent, generally, monoethanolamine (MEA) or a solid absorbent like lithium zirconate is used to dissolve CO2, but not the other components of a flue gas stream. C02-rich solution is typically pumped to a regeneration column, where CO2 is stripped out from the solution and the solvent recycled for a new batch of flue gas. The absorption equipment should be placed after the flue gas desulfurization-step and before the stack. Optimal conditions for absorption are low temperature and high pressure, making this the best location for absorption to occur. In addition, most solvents are easily degraded by compounds such as fly ash, other particulates, 80, (SO2, SO3) and (NO, NO2), so the absorption step must take place after electrostatic precipitation and desulfurization. In a typical absorption process, the C02-lean flue gas is either emitted to the atmosphere or possibly used in other applications e.g. chemical production). 

A tube reactor of 20 m was simulated to show the performance of the reactor as a function of the length. The thermodynamic upper limit of hydrogen purity on dry basis at 10 bar total pressure and a temperature of 848 K with lithium zirconate as acceptor is 91 mole%. Very long reactors and low space velocities are required to reach the equilibrium composition due to the limitations of the C02-capture kinetics. A contour plot of the dry hydrogen fraction is shown in Fig. 11.9. It is observed that... 

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