Ag-La loaded protonated carbon nitrides nanotubes (pCNNT) with improved charge separation in a monolithic honeycomb photoreactor for enhanced bireforming of methane (BRM) to fuels
Ag-La loaded protonated carbon nitrides nanotubes (pCNNT) with improved charge separation in a monolithic honeycomb photoreactor for enhanced bireforming of methane (BRM) to fuels
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DOI：
10.1016/j.apcatb.2019.01.076
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
Beenish Tahir;Muhammad Tahir;N. S. Amin
中科院分区：
文献类型：
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作者：
Beenish Tahir;Muhammad Tahir;N. S. Amin
采用无模板超声辅助一锅水热法制备了Ag-La修饰的质子化石墨氮化碳纳米管（pCNNT）。采用XRD、SEM、TEM、EDX、N2吸附、XPS、UV-vis DRS和PL光谱等表征手段对催化剂样品进行了表征。在固定床和整体式蜂窝光反应器系统中，考察了Ag-La修饰的pCNNT对甲烷干重整（DRM）和甲烷二重整（BRM）等不同甲烷重整反应的影响.优化后的3%Ag-5%La/pCNNT在紫外光下表现出更高的产率，这是由于产生了更多的电荷，具有更强的裂解稳定的CO2和CH 4分子的能力。更重要的是，与Ag-La负载的pCN纳米片相比，Ag-La负载的pCNNT的CO和H2产生性能分别高1.45和2.10倍。与固定床反应器相比，整体式光反应器中CO和H2的析出占主导地位。此外，BRM中CO、H2和CH 3OH的含量分别是DRM的1.79、2.12和2.13倍。由于Ag-La的协同效应和合适的氧化还原电位，BRM过程中有效的界面载体分离，可以归因于性能的改善。在负载Ag-La修饰的pCNNTs的整体式蜂窝光反应器中，BRM显著提高了量子产率，这是由于更大的光子能量利用率、更大的受照表面积、改善的吸附过程和具有有效电荷载流子利用率的表面反应用于CO2还原和CH 4/H2O氧化。根据表征分析和实验结果，提出了与Ag-La/pCNNT BRM工艺性能相匹配的反应机理。实验结果可为进一步开发用于光催化BRM应用的先进高效异质结构提供指导。
Well-designed Ag-La modified protonated graphitic carbon nitride nanotubes (pCNNT) are fabricated via a template-free sonicated assisted one-pot hydrothermal method. The structure and properties of the catalyst samples are obtained by XRD, SEM, TEM, EDX, N2-sorption, XPS, UV–vis DRS and PL spectroscopy characterization techniques. The effect of Ag-La-modified pCNNT is evaluated for different CH4reforming processes such as dry reforming of methane (DRM) and bi-reforming of methane (BRM), carried out in a fixed-bed and monolithic honeycomb photoreactor systems under UV and visible light irradiations. The optimized 3%Ag-5%La/pCNNT performance displayed increased productivity under UV-light due to more production of charges with strong ability for cleaving both stable CO2and CH4molecules. More importantly, the performance of Ag-La loaded pCNNT is 1.45 and 2.10 folds higher for CO and H2production, respectively compared with Ag-La loaded pCN nanosheets. CO and H2evolutions prevailed in a monolith photoreactor compared to fixed-bed reactor. Besides, the amount of CO, H2and CH3OH are 1.79, 2.12 and 2.13 folds higher in BRM compared to DRM. The improved performance can be ascribed to effective interfacial carrier separation due to Ag-La synergistic effect with suitable redox potentials for BRM process. The quantum yield is significantly enhanced with BRM in the monolithic honeycomb photoreactor loaded with Ag-La modified pCNNTs due to greater photon energy utilization, larger illuminated surface area, improved sorption process and surface reactions with efficient charge carrier utilization for CO2reduction and CH4/H2O oxidation. Reaction mechanism is proposed to commensurate with the performance of Ag-La/pCNNT for BRM process based on characterization analysis and experimental results. The experimental results could provide guidance for further development of advanced and highly efficient hetero-structures for photocatalytic BRM applications.