Hydrogenation Of Α-Pinene/Rosin Catalyzed By Janus Amphiphilic Hollow Nano Nickel-based Catalyst In Aqueous Phase

In recent years,due to the popularization of industrialization and the rapid consumption of fossil resources,the effective utilization of renewable resources has received extensive attention.Turpentine and rosin are popular renewable natural resources,and their hydrogenated products,cis-pinane and hydrogenated rosin,are widely used in various fields as important industrial intermediates.The catalysts for their reactions have low selectivity,difficult separation,and environmental pollution.And other issues,as a safe and cheap green solvent,water is increasingly used in organic catalytic reactions,but there is a problem of incompatibility with the reaction substrate.Researchers have found that a Janus amphiphilic hollow nanomaterial can utilize its unique properties.The amphiphilicity of the water phase realizes the organic combination of the water phase and the oil phase,thereby improving the reactivity in heterogeneous catalysis.On this basis,a Janus amphiphilic hollow nanocatalyst was developed in this thesis,and its catalytic activity was investigated withα-pinene and rosin as model compounds.Janus amphiphilic hollow nano material was synthesized by domain limiting carbonization with cetyltrimethylammonium bromide（CTAB）as template,ethylenediamine（EDA）as nitrogen source,phenolic resin as carbon source and tetraethyl silicate（TEOS）as silicon source.The morphology of the material was characterized and analyzed by SEM and TEM.It was confirmed that the material has a hollow structure with silica outer coating and carbon nitrogen doped skeleton inside,with regular morphology and uniform distribution.A series of structural characterization were carried out by N₂ adsorption desorption,XPS and Raman.It was found that the material contained a large amount of pyridine N,which was conducive to the binding with metal active sites.The prepared material had uniform mesoporous pore size（5.6nm）and large specific surface area(211m~2g^-1).Finally,through contact angle measurement and different emulsion bubble tests,it is proved that the material has two hydrophilic structure on the outer surface and hydrophobicity on the inner surface.The Janus amphiphilic carbon-silicon double-framework nanocatalyst Ni-B/Cx Ny@m Si O₂ was prepared by loading Ni-B amorphous alloy nanoparticles on amphiphilic carbon-silicon nanomaterials by impregnation reduction.The hollow structure of nano materials produces a large specific surface area,which is conducive to mass transfer and substrate enrichment.The doping of N atoms in the internal carbon skeleton allows the attachment of additional metal nanoparticles.The hydrophilic silica shell improves the stability and dispersion of the catalyst in the water system.Importantly,in the water/oil two-phase reaction system,the amphiphilic nano catalyst acts as a solid foaming agent,thus promoting the dissolution of H₂ and substrate contact.In addition,the synergistic effect of Ni and B significantly improved the catalytic activity.Under mild conditions（80℃,1MPa H₂,3 h）,the conversion of pinene was 98.85%and the selectivity of cis-pinane was 98.50%.The conversion rate ofα-pinene remained above 90.0%after the catalyst was reused for 8 times.Under the conditions of temperature 160℃,pressure 4.0 MPa and reaction time 4 h,the conversion of rosin is98.77%,the selectivity of tetrahydroabietic acid is 23.89%,and the content of dehydroabietic acid is less than 1.0%,which meets the standard of primary rosin.The catalyst can be stably reused for 6 times with almost no activity loss.The nanocatalyst Ni_a-W_b-B/Cx Ny@m Si O₂ was prepared by introducing the third component and loading the Ni-W-B three-component amorphous alloy onto the carrier by impregnation reduction.The addition of W brought more acidic sites to the catalyst.Py-FTIR and NH₃-TPD tests also confirmed that the addition of W introduced more weak acid sites into the system,mainly L acid.At the same time,the introduction of W can better regulate the electronic synergy between Ni-B and increase the activity and stability of the active sites of the catalyst.Under the conditions of temperature 80℃,pressure 2.0 MPa,Ni:W=1:0.5,4 ml of water and reaction time 3 h,the conversion of pinene hydrogenation was 98.81%,the selectivity was 98.39%,and the catalyst was reused for 9 times with almost no activity loss;Under the conditions of temperature140℃,pressure 4.0 MPa,Ni:W=1:1,water oil ratio 1:2 and reaction time 4 h,the conversion of rosin hydrogenation reaction is 99.13%,the selectivity of tetrahydroabietic acid is 27.37%,and the content of dehydroabietic acid is less than 1.0%,which meets the standard of super grade rosin.The catalyst can be reused for 9 times and shows good recoverability.A Janus amphiphilic hollow nanocatalyst loaded with amorphous alloys with different components was prepared in this paper,and the catalyst was used for the phase hydrogenation ofα-pinene and rosin,showing high activity and high performance.Stability and good recyclability.This study provides a new green and efficient way for the deep processing and utilization of natural biomass resources,and provides a theoretical basis for non-noble metal catalyst aqueous catalytic organic reaction.