Synthesis, characterization and evaluation of SodiumDoped lithium zirconate as a high temperature CO2 absorbent

摘要

A novel modification of the steam methane reforming process (SMR) for the production of hydrogen, where the reforming, water gas shift and solid CO2 capture reactions are combined in one single process step (Sorption Enhanced reforming, SER) leading to the production of high purity hydrogen. An essential part of this process is the CO2 solid acceptor, which must possess adequate absorption capacity and fast absorption/regeneration kinetics. Recently, Li2ZrO3 has been proposed as CO2 acceptor due to its high thermal stability. However, CO2 absorption kinetics for this material is significantly slow. The objective of the present work is to dope Li2ZrO3 with Na aiming to increase its CO2 absorption capacity and kinetics. Li2ZrO3 was doped with 2, 5, 10 and 15% weight with NaNO3 using the incipient wetness and calcined at 900 degrees C. XRD was used to determine the crystalline structure of the materials. CO2 absorption evaluation of the samples was performed through TGA at 600 degrees C (80% CO2/Ar), while regeneration was at 850 degrees C (Air/Ar). Results reveal an increase of in the absorption capacity of the Na doped materials with respect to pure Li2ZrO3. XRD patterns of the doped samples suggest a limited substitution of Li by Na atoms within the Li2ZrO3 structure.