Sun Shuzhuang, Zhang Chen, Chen Sining, Zhao Xiaotong, Wang Yuanyuan, Xu Shaojun, Wu Chunfei
School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast BT7 1NN, UK.
Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
R Soc Open Sci. 2023 Apr 5;10(4):230067. doi: 10.1098/rsos.230067. eCollection 2023 Apr.
Achieving carbon neutrality is one of the most important tasks to meet the environmental challenges due to excessive CO emissions. Integrated CO capture and utilization (ICCU) represents an effective process for direct utilization of CO-contained exhaust gas (e.g. flue gas), in which converting the captured CO into CO via reverse water-gas shift (RWGS) reaction is a promising route. The dual functional materials (DFMs), containing CO adsorbents and catalysts, are widely applied to achieve ICCU. The conventional active metals (Ni, Fe, etc.)-based DFMs and non-transition metal DFMs (e.g. CaO) are restricted by low CO selectivity, catalytic efficiency or CO generation in the CO capture step. To address the above obstructs in the application of DFMs, the metal oxides-based DFMs, MO-CaO (M = Al, Ce, Ti or Zr), are synthesized and evaluated. The CeO-CaO outperformed the other metal oxides-based DFMs and possessed significantly improved catalytic performance. It is found that 33% CeO-CaO DFM displayed approximately 49% CO conversion and approximately 100% CO selectivity in integrated CO capture and reverse water-gas shift reaction (ICCU-RWGS) at 650°C, while CaO-alone only achieved approximately 20% CO conversion at the same condition. The surface basicity of CeO is revealed to contribute to the improved catalytic performance by enhancing CO chemisorption and activation in the hydrogenation step. Furthermore, CeO-CaO material possessed excellent cycle stability in 20 cycles ICCU-RWGS, achieving a sustainable and high-efficient performance in CO conversion and CO selectivity.
实现碳中和是应对因二氧化碳过度排放而带来的环境挑战的最重要任务之一。集成式二氧化碳捕集与利用（ICCU）是一种直接利用含二氧化碳废气（如烟道气）的有效工艺，其中通过逆水煤气变换（RWGS）反应将捕获的二氧化碳转化为一氧化碳是一条很有前景的途径。包含一氧化碳吸附剂和催化剂的双功能材料（DFMs）被广泛应用于实现ICCU。传统的基于活性金属（镍、铁等）的双功能材料和非过渡金属双功能材料（如氧化钙）受到一氧化碳选择性低、催化效率低或在二氧化碳捕集步骤中一氧化碳生成量的限制。为了解决双功能材料应用中的上述障碍，合成并评估了基于金属氧化物的双功能材料MO-CaO（M = 铝、铈、钛或锆）。CeO-CaO的性能优于其他基于金属氧化物的双功能材料，并且具有显著提高的催化性能。研究发现，在650°C的集成式二氧化碳捕集与逆水煤气变换反应（ICCU-RWGS）中，33%的CeO-CaO双功能材料显示出约49%的一氧化碳转化率和约100%的一氧化碳选择性，而单独的氧化钙在相同条件下仅实现了约20%的一氧化碳转化率。CeO的表面碱性通过增强氢化步骤中的一氧化碳化学吸附和活化作用，有助于提高催化性能。此外，CeO-CaO材料在20次ICCU-RWGS循环中具有优异的循环稳定性，在一氧化碳转化率和一氧化碳选择性方面实现了可持续的高效性能。
