(228g) Ca Based High Temperature CO2 Absorbents for Sorption Enhanced Reforming Process
AIChE Spring Meeting and Global Congress on Process Safety
2008 Spring Meeting & 4th Global Congress on Process Safety
11th Topical on Refinery Processing - Jointly Co-sponsored with ACS
CO2 and Sulfur Issues In Refineries
Thursday, April 10, 2008 - 11:10am to 11:35am
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 700oC 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.