(544ez) Direct Conversion of Carbon Dioxide into Value-Added Chemicals

The continued growth of anthropogenic emissions of CO2 caused the climate change. Carbon capture and storage (CCS) and carbon capture and utilization (CCU) have been proposed as the possible technologies to mitigate climate change. Transformation of CO2 to valuable chemicals can not only mitigate CO2 emissions, but also reduce consumption of fossil resources. For CO2 conversion, in my group, the research focused on the synthesis of CH4, CO and hydrocarbons. It was found that CO2 was converted into CH4 with high selectivty and stability over ZrO2 based catalysts; CO2 was converted into CO with high selectvity and activity over In2O3/TiO2 catalystsï¼› it was converted into hydrocarbons with high activity and selectivty over Fe-based catalysts.

(1) The conversion of CO2 into methane over Co/ZrO2, it was found that Co/ZrO2 catalyst exhibited high activity and stability through adjusting the metal-support interaction and the special metal-support interface, such as Co-Zr interface. The 10Co/ZrO2 catalyst showed high activity with CO2 conversion of 92.5 % and CH4 selectivity of 99.9 % without deactivation even after 300 h time on stream (TOS). However, the 10Co/Al2O3 catalyst gave a lower CO2 conversion of 77.8 % which decreased to 38.6 % after 300 h TOS. Moreover, It was found that the citric acid treatment increases the activity greatly due to the increases in the dispersion of Co. TiO2 is also a good support for the Co-based catalysts, but the crystal phase has great influence on the activity and product distribution.

(2) The conversion of CO2 into CO over In2O3/TiO2 catalyst, it was found that the crystal phase also has great influence on the activity, In2O3/rutile TiO2 exhibited higher activity than In2O3/anatase TiO2.

(3) The conversion of CO2 into olefins over Fe-based catalysts, FeZn-NC and FeZnK-NC were prepared and exhibited high activity with 29.3 % and 34.6 % CO2 conversion, respectively. More importantly, the selectivity to value-added hydrocarbons (i.e., C2-C4= and C5+), which are of great importance to chemical industry and energy, was prominent over these two catalysts, and higher than 54 C-mol%. it was also found that Fe5C2 played a key role in the CO2 conversion, different from the role in the CO conversion. Fe3O4 and χ-Fe5C2 containing catalysts displayed the best performance. However, metallic iron and/or θ-Fe3C containing catalysts exhibited relative inferior performance.