Catalytic Conversion Of Lignin By Ni-based Bimetallic/CDs Composite Nanoparticles

The content of lignin in biomass is relatively high.The development and utilization of lignin into high-grade fuels or industrial chemicals is a way to effectively utilize biomass energy.Due to the synergy between the two metals,bimetallic catalysts show better performance than single metals,and are often used in many aspects such as machinery,construction and chemical production.As a new type of carrier,carbon nanodots have a large number of holes and electrons and abundant functional groups on the surface,making carbon nanodots can be used as oxidants,reducing agents or metal carriers.Carbon nanodots are becoming more and more popular due to their excellent chemical properties.Many scholars have researched and reported and are widely used.There are many researches on the preparation of catalysts from carbon nanodots combined with single metals,and there are certain results.However,there are few researches on the preparation of composite nanocatalysts from bimetals and carbon dots and the application of the catalysts in the catalytic conversion of lignin,so this article Certain researches and discussions have been made on the selection of carbon point raw materials,the matching of bimetals,the preparation of catalysts,and the catalytic liquefaction of lignin under supercritical conditions.The properties of carbon nanodots are related to their morphology,particle size and distribution.In this paper,trisodium citrate,citric acid monohydrate,malic acid and glucose were used as raw materials,and carbon nanodots were prepared under hydrothermal reaction conditions at a reaction temperature of 210 ?,a time of 4 h,and a rotation speed of 300 r/min.According to TEM,Characterization analysis such as FT-IR,UV-Vis absorption spectroscopy and XRD shows that the carbon nanodots prepared with trisodium citrate as the carbon source have a relatively regular spherical appearance,small particle size and uniform distribution;the surface of the carbon nanodots There are a large number of functional groups such as hydroxyl,amino and carboxyl groups;according to the maximum absorption wavelength of the ultraviolet-visible absorption spectrum of the carbon nanodots aqueous solution,it is determined that the carbon nanodots have the nature of the C=O bond functional group n??* electronic transition.Through various characterizations The comparison shows that the carbon nanodots prepared with trisodium citrate as the carbon source have the best effect.Ni Pd,Ni Ru and Ni Re bimetallic nanoparticles were prepared by hydrothermal method at a reaction temperature of 180 ?,a time of 8 h,and a rotation speed of 300r/min.The metal molar ratio was changed to 2:1,1:1,and 1:2 Through the characterization methods of TEM,XRD and EDS,the characterization situation of bimetallic nanoparticles prepared with different metal molar ratios was analyzed,and the results showed that when the metal molar ratio is Ni:Pd=1:2,Ni:Ru=1:1,The bimetallic nanoparticles prepared when Ni:Re=1:1 have uniform particle size and good dispersibility.Using two different preparation methods,room temperature stirring method and hydrothermal method,the carbon nanodots and Ni-based bimetallic nanoparticles were used to prepare Ni-based bimetal/CDs composite nano-catalysts.TEM analysis showed that the composite nano-catalyst prepared by hydrothermal method was in shape.Uniform appearance,uniform particle size,and good dispersion.The prepared Ni-based bimetal/CDs composite nanocatalyst was used for the catalytic liquefaction of lignin.The conversion rate of lignin with the addition of Ni Pd/CDs catalyst increased from 51.47% to 79.57%,and there were many types of lignin liquefaction products,mainly The products are phenols,esters and aldehydes.