Snythesis Of Platinum(Palladium)-Based Nanocatalysts And Their Catalytic Performance For Selective Hydrogenation Of Furfural

In order to achieve sustainable development,researchers propose to use lignocellulose or agricultural waste to produce second-generation biofuels.China is a large agricultural country with abundant agricultural and forestry crop wastes.Recycling and processing these wastes and secondary development can not only alleviate the energy crisis,but also reduce environmental pollution.Rice straw,straw,sawdust and other agricultural and forestry crop wastes contain a large amount of cellulose,which can be hydrolyzed and dehydrated to produce furfural,which is simple and easy to obtain.Therefore,the efficient utilization of furfural has become a research hotspot,and the catalytic hydrogenation of furfural can synthesize a variety of high value-added products.In this work,trimetallic catalysts with different structures are prepared by different methods,and furfural is selectively hydrogenated to obtain furfuryl alcohol,2-methylfuran and tetrahydrofurfuryl alcohol.The specific research content can be divided into the following three parts:（1）Use hydrazine hydrate reduction and chemical displacement at room temperature,and control the synthesis process conditions to prepare a"Pd/transition metal/transition metal hydroxide/C multi-level loading"nanostructured catalyst,and explore the construction rules of multi-level loading nanostructures.The transition metal is Ni,Co or Ni Co;the transition metal hydroxide is Ni（OH）₂,Co（OH）₂ or Ni（OH）₂-Co（OH）₂.The effects of reaction temperature,reaction time,metal loading and roasting temperature on the hydrogenation reaction of furfural were investigated.The study found that the catalytic performance of the uncalcined trimetallic catalyst is better than that of the monometallic,bimetallic and trimetallic catalysts calcined at different temperatures.PdNiCo/C showed high excellent catalytic performance（furfural conversion-99.8%,furfural alcohol Selectivity-97.8%）at quite low reaction temperatures,and had good stability.The as-prepared catalysts were characterized by AC HAADF-STEM、XANES、EXAFS.In the PdNiCo/C catalyst,Pd is supported on NiCo/Ni（OH）₂-Co（OH）₂ nanoparticles in the form of atoms and clusters.（2）The PdNiCo/N-CNTs catalyst was prepared at room temperature via sodium borohydride reduction method.Other metallic catalysts were obtained by the same preparation method.The XRD,XPS,TEM,HRTEM,STEM-EDS elemental mapping and line-scanning characterization results confirmed the formation of PdNiCo alloy in the PdNiCo/CNTs and PdNiCo/N-CNTs catalyst.Among as-prepared catalysts,the PdNiCo/N-CNTs catalyst showed most excellent catalytic performance and highest selectivity to tetrahydrofurfuryl alcohol for furfural selective hydrogenation（conversion of furfural-100%,selectivity to tetrahydrofurfuryl alcohol-97.1%）.For the PdNiCo/N-CNTs catalyst,PdNiCo alloy nanostructure;higher specific surface area;the electronic synergy effect between Pd and Ni（Co）;there was also a synergistic effect of electron between PdNiCo alloy nanoparticles and nitrogen-doping carbon nanotubes;in addition,the PdNiCo/N-CNTs catalyst had much more weak basic sites.The above-mentioned properties were conducive to the hydrogenation of furfural to produce tetrahydrofurfuryl alcohol.Therefore,the catalyst has good application prospects.（3）A nanostructured catalyst with"Pt/transition metal/transition metal oxide/C multi-level loading"was prepared,and the construction law of multi-level loading nanostructures was explored.The transition metal is Cu,Co or CuCo.The effects of reaction temperature,reaction time,metal loading and roasting temperature on the hydrogenation reaction of furfural were investigated.The study found that the catalytic performance of the trimetallic catalyst calcined at 180°C is better than that of the monometallic,bimetallic and trimetallic catalysts calcined at different temperatures.PtCuCo/C showed high excellent catalytic performance（furfural conversion-93.1%,2-methylfuran Selectivity-90.3%）under quite mild reaction conditions（180°C,1 h,3.0 MPa H₂）.The catalyst was characterized by AC-STEM,XANES,EXAFS and other characterization methods,which proved that Pt in the PtCuCo/C catalyst exists in the form of single atoms and clusters,and there is a synergistic effect between Pt,Cu,and Co related species.