采用固相反应法制备钙钛矿型吸附剂Ba0.95Ca0.05CO0.5Fe0.5O3-δ(BCCF)和Sr0.95Ca0.05Co0.8Fe0.2O3-δ(SCCF).XRD结果显示两种物质均形成了纯的钙钛矿结构.利用TGA实验研究了吸附剂的理论氧吸附容量,氧吸附/脱附转化率及循环稳定性.结果显示,由于785℃时,吸附剂SCCF发生了氧空位的无序-有序的相转变,SCCF比BCCF具有更高的理论氧吸附容量.在700～900℃范围内,吸附剂的氧吸附/脱附转化率随着温度的升高而增大,但脱附过程都没有进行完全,吸附剂BCCF、SCCF的脱附转化率只达到了59.44％、38.36％.在测试温度范围内,BCCF和SCCF的最佳氧脱附温度是850℃和900℃,最佳的氧吸附温度应分别大于850℃和800℃.多次吸附/脱附循环试验显示BCCF吸附剂具有很高的活性和循环稳定性,而SCCF经过3次循环后,其转化率明显降低.%Perovskite-type Ba0.05Ca0.05Co0.5Fe0.5O3-δ(BCCF) and Sr0.05Ca0.05Co0.8Fe0.2O3-δ (SCCF) sorbents have been prepared by solid state reaction method. The XRD patterns show that both samples formed pure perovskite phase structure. The theoretical oxygen sorption capacity, oxygen sorption/desorption rates and the cycle behavior of the sorbents were investigated by TGA. The results show that the theoretical oxygen sorption capacity of SCCF is higher than that of BCCF, duo to the oxygen vacancy disorder-order phase transition at 785℃. for SCCF. At a range of 700～900℃, the oxygen sorption/desorption conversion rate increases with increasing temperature, but the oxygen desorption is not completed in the whole tested temperature range, the highest oxygen desorption conversion rates are only 59.44%, 38.36% for BCCF and SCCF, respectively. At the test temperature range, optimal temperatures for oxygen desorption processes are 850 and 800℃, and optimal sorption temperatures should be higher than 900 and 800℃ for BCCF and SCCF, respectively. Multiple sorption and desorption cycles indicate that BCCF sorbent has high activity and cyclic stability, while the conversion rates of SCCF decrease significantly after three cycles.
展开▼
