Abstract This present study investigated the catalytic effect of Na2CO3 on the reduction of ferromanganese spinel (MnFe2O4) using biochar as reducing agent. The reduction of the MnFe2O4-biochar composite briquettes at 1050 °C for 30 min showed that the iron metallization degree of the reduced briquettes increased from 61.1% to 84.2%, with significant decrease of initial reduction temperature due to the addition of 5 wt% Na2CO3. There also existed higher CO and CO2 concentrations in the off-gas in the presence of Na2CO3. According to the first-principles calculations, these differences were attributed to the reaction between Na2CO3 and carbon which produced oxygen vacancies on the Na2CO3 surface. These vacancies were then filled by the oxygen atoms of CO2, forming CO which was desorbed from the surface of Na2CO3 before it participated in the reduction. By creating oxygen vacancies through its reaction with carbon, Na2CO3 played a catalytic role in the reduction process.

中文翻译：

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碳酸钠在还原锰铁尖晶石中的催化作用

摘要 本研究研究了 Na2CO3 对使用生物炭作为还原剂还原锰铁尖晶石 (MnFe2O4) 的催化作用。MnFe2O4-生物炭复合煤球在 1050 ℃还原 30 min 表明，还原煤球的铁金属化度从 61.1% 增加到 84.2%，由于加入 5 wt% Na2CO3，初始还原温度显着降低. 在存在 Na2CO3 的情况下，废气中还存在更高的 CO 和 CO2 浓度。根据第一性原理计算，这些差异归因于 Na2CO3 与碳之间的反应，在 Na2CO3 表面产生了氧空位。然后这些空位被 CO2 的氧原子填充，形成 CO，在参与还原之前从 Na2CO3 表面解吸。通过与碳反应产生氧空位，Na2CO3 在还原过程中起到了催化作用。