Simultaneous conventional and microwave heating for the synthesis of adsorbents for CO2 capture: comparative study to pristine technologies

Microwave has become an attractive technology in the valorisation of renewable biomass and in the mitigation of challenges of climate change. In this work, the synergic effects of coupling microwave and mild conventional heating conditions has been investigated in preparing engineered ultra-micropore carbons from lignocellulosic biomass. The processing conditions were systematically investigated and correlated to the physicochemical properties of activated carbons produced and their performance in post-combustion CO2 capture. The highest CO2 uptake (225 mg g-1) was achieved for the hybrid carbon produced at low temperature (600 °C) and modest microwave intensity. The synergic effect of hybrid heating was confirmed by the significant CO2 uptake increase up to 80 and 60 % for the activated carbons prepared by microwave and conventional heating, respectively. The enhanced adsorption was confirmed by cyclic regeneration up to 99 % after 16 adsorption-desorption cycles, showing a linear correlation between the surface area, micropore volume and CO2 uptake. The Pseudo-first order model accurately describes the adsorption phenomena, indicating that physisorption is the primary mechanism governing the process. The results acquired from this study highlight the process intensification in the synthesis of porous materials with comparable properties that are typically attained in conventional heating using energy intensive conditions. Additionally, this approach reveals the benefits of conventional treatment for increasing the material’s microwave susceptibility and as consequence to reduce the processing time by microwave heating. The synergic effects confirms the potential of hybrid heating for applications where fast and selective heating is paramount.

微波技术已成为可再生生物质增值利用（valorisation of renewable biomass）及应对气候变化挑战领域的研究热点。本研究探讨了微波与温和常规加热耦合条件下，以木质纤维素生物质（lignocellulosic biomass）为原料制备工程化超微孔碳（ultra-micropore carbons）的协同效应。系统研究了制备工艺条件，并将其与所得活性炭的理化性质及其在燃烧后CO₂捕集（post-combustion CO₂ capture）中的性能进行关联分析。在低温（600℃）及适度微波强度下制备的混合碳材料，其CO₂吸附量最高，达225 mg/g。与单独微波加热或常规加热制备的活性炭相比，混合加热制备的活性炭CO₂吸附量分别提升了80%和60%，这证实了混合加热的协同效应。经过16次吸附-解吸循环后，材料的循环再生率仍高达99%，证实了其吸附性能的增强；同时，材料的比表面积、微孔体积与CO₂吸附量之间存在线性相关性。伪一级动力学模型（Pseudo-first order model）可准确描述该吸附过程，表明物理吸附（physisorption）是主导机制。本研究结果表明，通过该工艺可强化多孔材料的合成过程，在能耗较低的条件下获得与传统高能耗加热工艺相当性能的材料。此外，该方法还揭示了常规预处理可提高材料的微波敏感性（microwave susceptibility），从而缩短微波加热的处理时间。这种协同效应证实了混合加热技术在快速选择性加热至关重要的应用场景中具有巨大潜力。