Chang Po-Hsueh, Hsu Hua-Pei, Wu Szu-Chen, Peng Cheng-Hsiung
Department of Chemical and Materials Engineering, Minghsin University of Science and Technology, Xinxing Road, Xinfeng, Hsinchu 30401, Taiwan.
Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan.
Materials (Basel). 2020 Sep 26;13(19):4297. doi: 10.3390/ma13194297.
Limestone is a relatively abundant and low-cost material used for producing calcium oxide as a CO adsorbent. However, the CO capture capacity of limestone decreases rapidly after multiple carbonation/calcination cycles. To improve the CO capture performance, we developed a process using limestone to transform the material into a rod Ca-based metal-organic framework (Ca-MOF) via a hydrothermal process with the assistance of acetic acid and terephthalic acid (HBDC). The structural formation of rod Ca-MOF may result from the (200) face-oriented attachment growth of Ca-MOF sheets. Upon heat treatment, a highly stable porous rod network with a calcined Ca-MOF-O structure was generated with a pore distribution of 50-100 nm, which allowed the rapid diffusion of CO into the interior of the sorbent and enhanced the CO capture capacity with high multiple carbonation-calcination cycle stability compared to limestone alone at the intermediate temperature of 450 °C. The CO capture capacity of the calcined porous Ca-MOF-O network reached 52 wt% with a CO capture stability of 80% after 10 cycles. The above results demonstrated that rod Ca-MOF can be synthesized from a limestone precursor to form a porous network structure as a CO capture sorbent to improve CO capture performance at an intermediate temperature, thus suggesting its potential in environmental applications.
石灰石是一种相对丰富且低成本的材料，用于生产作为二氧化碳吸附剂的氧化钙。然而，石灰石在多次碳酸化/煅烧循环后，其二氧化碳捕获能力会迅速下降。为了提高二氧化碳捕获性能，我们开发了一种工艺，利用石灰石在乙酸和对苯二甲酸（HBDC）的辅助下，通过水热法将该材料转化为棒状钙基金属有机框架（Ca-MOF）。棒状Ca-MOF的结构形成可能源于Ca-MOF片层的（200）面取向附着生长。经过热处理，生成了具有煅烧Ca-MOF-O结构的高度稳定的多孔棒状网络，其孔径分布为50-100纳米，这使得二氧化碳能够快速扩散到吸附剂内部，并在450℃的中间温度下，与单独的石灰石相比，以高的多次碳酸化-煅烧循环稳定性提高了二氧化碳捕获能力。煅烧后的多孔Ca-MOF-O网络的二氧化碳捕获能力达到52重量%，经过10次循环后，二氧化碳捕获稳定性为80%。上述结果表明，棒状Ca-MOF可以由石灰石前驱体合成，形成多孔网络结构作为二氧化碳捕获吸附剂，以提高中间温度下的二氧化碳捕获性能，从而表明其在环境应用中的潜力。
