The role of nickel addition on the CO2 chemisorption enhancement in Ni-containing Li2CuO2: Analysis of the cyclability and different CO2 partial pressure performance

Abstract

This work analyzes the inclusion of nickel ions in lithium cuprate (Li2CuO2) as a solid solution or outside forming composites. All the compounds were obtained by solid-state reaction: pristine Li2CuO2, solid solutions (Li2Cu1-xNixO2, with x ≤ 0.10) and composites (Li2CuO2-LiNiO2, with x > 0.10). The materials were characterized by XRD, N2 adsorption-desorption, SEM and NMR of solids. The CO2 capture capacity of solid solutions and composite samples was evaluated, in comparison to the pristine lithium cuprate. At PCO2 = 1, the Li2Cu0.9Ni0.1O2 solid solution composition exhibits the best CO2 chemisorption at high temperature (700 °C), although all Ni-containing Li2CuO2 samples showed slower kinetics and lower temperature dependence than pristine lithium cuprate. It was attributed to structural and chemical variations on Li2CuO2 produced by the Ni ions. In fact, when the CO2 partial pressures were equal to 0.2 or 0.05, the nickel presence induced a stabilization during CO2 capture, averting temperature displacement maintained the highest chemisorption at 700 °C where the regeneration of the material is optimal. At PCO2 of 0.2, pristine Li2CuO2 shifted its highest capture from 700 to 650 °C, while Ni-containing samples preserved the best CO2 capture at 700 °C. Then, cyclic experiments were performed at 700 °C with PCO2 = 0.2 where the solid solution sample demonstrated a better stability than that observed on the pristine Li2CuO2 sample.