Fabrication of Microwave-responsive CMF@CoS2/MoS2 Catalyst and Highly Efficient Reforming of Lignin Vapor by Microwave Irradiation
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@CoS2/MoS2 catalyst was prepared by a one-step hydrothermal method using Anderson-type polymetallic oxides(NH4)3[CoMo6O24H6]·6H2O as precursors.The morphological features and microwave absorption properties of CMF@CoS2/MoS2 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@CoS2/MoS2 is composed of nanoflowers deposited on the CMF 3D skeleton.And CMF@CoS2/MoS2 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@CoS2/MoS2 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@CoS2/MoS2 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@CoS2/MoS2 catalyst.In conclusion,this work pro-vides a promising method for the efficient production of phenols from lignin over bifunctional CMF@CoS2/MoS2 catalyst with"wave-absorbing heat transfer"and"catalytic conversion".
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