NiFe_2O_4直接分解二氧化碳成碳循环反应过程结构演变研究

STUDY ON THE STRUCTURE CHANGE OF NiFe_2O_4 DURING THE CYCLE REACTION OF DECOMPOSITION OF CO_2 TO C

用XRDRietveld分析法 ,对共沉淀法制备的NiFe2 O4在H2 /CO2 循环反应中的结构演变进行研究 ,发现随着循环反应次数的增加 ,NiFe2 O4物相的含量逐渐降低 ,FexNi1 -x物相的含量及其 ( 2 0 0 )衍射的平均晶粒逐渐增大 ,并出现Fe3C物相 ,其含量增长较快 .纯NiFe2 O4经 1 5次循环反应后 ,体系中NiFe2 O4物相的含量只剩下 5 %左右 ,样品基本失去分解CO2 的活性 .NiFe2 O4掺杂 4%铬后 ,明显提高了NiFe2 O4骨架结构的稳定性 ,虽经 5 0次H2 /CO2 循环反应 ,体系中NiFe2 O4物相含量仍然有 2 0 % ,分解CO2 的活性仍达到初始活性的 40 % .

The structure change of NiFe 2O 4 prepared by co precipitation during H 2/CO 2 cycle reaction was determinded using XRD Rietveld analysis The results showed that when the cycle reaction times were increased,the phase abundaqdnce of NiFe 2O 4 decreased rapidly ,but the phase abundance of Fe X Ni 1- X and crystallite size of Fe X Ni 1- X (200)direction increased gradually,at the same time,there appeared the phase of Fe 3C whose content increased fast After 15 cycles,the phase abundance of NiFe 2O 4 is no more than 5%,simultaneously,the sample almost had no CO 2 decomposition activity When NiFe 2O 4 was doped with 4% Cr 3+ ,its structure stability was dramatically raised After 50 cycles,the phase abundance of NiFe 2O 4 also had 20% whose activity of CO 2 decomposition was still 40% as much as initial one