成型方法对Ni-CaO双功能材料CO2吸附与催化转化一体化性能的影响

The effect of granulation on the structure and integrated CO2 capture and conversion performance of Ni-CaO dual function materials

摘要:

CO2捕集-转化一体化工艺是实现碳中和的关键负排放技术，而兼具吸附和催化活性的双功能材料构筑是关键。采用挤压法、挤压滚圆法和压片法构筑了圆柱状、球形和片状的Ni-CaO双功能材料，探究了成型方法对Ni-CaO双功能材料的结构和CO2吸附-催化一体化性能的影响。研究发现，成型方法会破坏Ni-CaO双功能材料的孔隙结构，对其CO2体相扩散和吸附产生不利影响。Ni-CaO-P在650oC和10%CO2气氛下的吸附容量高达14.28 mmol CO2/g，在5%H2气氛下原位逆水煤气变换的CO产量达5.63 mmol CO/g。成型Ni-CaO双功能材料的CO2吸附容量降至7.28~9.78 mmol CO2/g，CO2催化转化率得到明显提升。成型方法有利于提升Ni-CaO双功能材料CO2吸附的循环稳定性。在12次循环后，未成型Ni-CaO-P的CO2吸附容量循环衰减率达31.37%，而成型Ni-CaO双功能材料的循环衰减率为9.36~24.23%。

Abstract:

Integrated CO2 capture and conversion (ICCC) represents a key negative emission technology to achieve carbon neutrality, and the construction of dual function materials (DFMs) with high CO2 uptakes and catalytic activity is essential. In this work, cylindrical, spherical and flake Ni-CaO DFMs were synthesized by the extrusion, extrusion-spherization and squashing methods, respectively, and effect of granulation on the structure and ICCC performance of Ni-CaO DFMs was investigated. Results indicated that granulation adversely affected the CO2 bulk diffusion and adsorption since it would destroy the porous structures of DFMs. The Ni-CaO-P exhibited a high CO2 uptake of 14.28 mmol CO2/g in 650°C and 10%CO2, and a high CO yield of 5.63 mmol CO/g in reverse water-gas shift (RWGS) reaction in 5%H2. Compared to the powdered DFMs, CO2 adsorption capacities of the Ni-CaO DFMs pellets decreased significantly to 7.28~9.78 mmol CO2/g, while the catalytic conversion rate of CO2 has been significantly improved. Granulation played an important role in stabilizing the CO2 uptakes of the Ni-CaO DFMs pellets in multiple cycles. The Ni-CaO-P exhibited a high loss-in-capacity of 31.37% for CO2 capture within 12 cycles, while the loss-in-capacity of the DFMs pellets was lower (9.36~24.23%).