(228g) Ca Based High Temperature CO2 Absorbents for Sorption Enhanced Reforming Process

There are several obstacles to overcome to materialize industrial level of sorption enhanced reforming process. One of the major problems of SERP is poor thermal cyclic stability of CO₂ absorbent(CaO). To dates, numerous research results showed that the repetitive absorption and desorption of CO₂ cause sintering or agglomeration of the absorbent particles resulting in drastic reduction of CO₂ absorption capacity along with the increased cycle number. In this study, Ca-based CO₂ absorbents were synthesized and modified to achieve the cyclic stability. The cyclic CO₂ absorption/desorption tests have been carried out in a thermal gravimetric analyzer using the prepared absorbent. Among the attempts to synthesize the absorbent, liquid phase methods with addition of alumina precursor produced the ultra stable high temperature CO₂ absorbents. Absortion/desorption test using the absorbent at 700^oC with changing gas atmosphere showed stable CO₂ gain of 45 wt% over 100 cycles. CO₂ absorption rate was very fast and consistent for each cycle. X-ray diffraction analysis revealed the development of micro porous structure inside of the absorbent during early cycles of absorption/desorption. Focused ion beam (FIB) investigation on cross-section of the absorbent showed major porous structure was developed in the Al rich region. Therefore, it is believed the compound containing Ca and Al formed path ways for fast CO₂ diffusion.

Also, various catalyst metal precursors were used to prepare catalyst incorporated absorbents. The prepared catalyst-absorbent materials were tested in a fixed bed reactor to simulated SERP process and its results were compared with that of physical mixture of commercial catalyst and the CO₂ absorbent.