微波响应型CMF@CoS_(2)/MoS_(2)催化剂的制备及其用于木质素蒸气的催化重整

Fabrication of Microwave-responsive CMF@CoS_(2)/MoS_(2) Catalyst and Highly Efficient Reforming of Lignin Vapor by Microwave Irradiation

本研究以Anderson型多金属氧酸盐(NH_(4))_(3)[CoMo6O_(24)H_(6)]·6H_(2)O为前驱体,采用一步水热法制备微波响应型CMF@CoS_(2)/MoS_(2)催化剂.当微波频率为2.45 GHz时,催化剂拥有良好的微波吸收性能(介电损耗正切角值0.23),证明了其拥有优异的微波响应能力.木质素蒸气微波辅助催化解聚(MACD)实验表明,CMF@CoS_(2)/MoS_(2)显著提高了单酚产率(59.30%)和苯酚选择性(24.69%).多物理场耦合分析表明,CMF@CoS_(2)/MoS_(2)由于其优异的微波吸收性,能够通过“热点效应”增强局部反应温度,使木质素蒸气(570℃)吸附于高温CoS_(2)/MoS_(2)活性组分(910℃)表面进一步促进其催化重整.本工作开发的新型微波响应型CMF@CoS_(2)/MoS_(2)催化剂为从木质素炼制高价值酚类平台化合物提供了新的途径.

To take the place of non-renewable resources derived from traditional petrochemical energy conversing of lignin into high-value platform chemicals has become one of the future research hotspots.Among many conversion technologies,microwave-assisted catalytic depolymerization technology is widely used in the catalytic reforming of lignin due to its ad-vantages of block heating rate,low energy consumption,high product selectivity,etc..The selection of catalysts plays a cru-cial role in the reforming of lignin.In this work,microwave-responsive CMF@CoS_(2)/MoS_(2) catalyst was prepared by a one-step hydrothermal method using Anderson-type polymetallic oxides(NH_(4))_(3)[CoMo_(6)O_(24)H_(6)]•6H_(2)O as precursors.The morphological features and microwave absorption properties of CMF@CoS_(2)/MoS_(2) catalysts were characterized through scanning electron microscope(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),transmission electron microscope(TEM)and 3656A vector network analyzer.The results showed that CMF@CoS_(2)/MoS_(2) is composed of nanoflowers deposited on the CMF 3D skeleton.And CMF@CoS_(2)/MoS_(2) has excellent microwave absorption properties(di-electric loss angle tangent of 0.23).The catalytic reforming of lignin vapor was carried out using a designed dynamic vapor flow reaction system,and the results showed that the CMF@CoS_(2)/MoS_(2) catalyst possessed highly efficient catalytic reform-ing ability.The monophenol yield(59.30%)and phenol selectivity(24.69%)of the lignin depolymerization product were increased under the reaction conditions of 400 s,1000 W,and 600 mL/min N2.Finite element analysis of the micro-wave-assisted catalytic depolymerization(MACD)of lignin reveals that the CMF@CoS_(2)/MoS_(2) is capable of generating a“hotspot”effect under microwave irradiation to raise the local temperature of the 3D skeleton to 910℃due to its excellent microwave absorption properties,which is a good example of the MACD of lignin.The heat exchange of lignin vapor with a lower temperature(570℃),captured during depolymerization,further promotes the catalytic reforming of lignin vapor.This is key to the efficient catalytic reforming of lignin vapor over the CMF@CoS_(2)/MoS_(2) catalyst.In conclusion,this work pro-vides a promising method for the efficient production of phenols from lignin over bifunctional CMF@CoS_(2)/MoS_(2) catalyst with“wave-absorbing heat transfer”and“catalytic conversion”.