Research On The Functionalization Of Magnetic Materials And Its Catalytic Synthesis Of Biomass-based Ester Fuels

Concern over the economics of accessing fossil fuel reserves,and widespread acceptance of the anthropogenic origin of rising CO₂ emissions and associated climate change from combusting such carbon sources,is driving academic and commercial research into new routes to sustainable fuels to meet the demands of a rapidly rising global population.With respect to this,biomass offers the most readily implemented,low-cost solution to a drop-in transportation fuel for blending with/replacing conventional diesel via the biorefinery concept.Currently,bio-based ester fuels including biodiesel?fatty acid methyl ester,FAME?and alkyl levulinate?AL?that are manufactured directly from sustainable biomass resources through the environmentally-friendly process using functional catalysts is of great interest.Centering on the two key issues of"effective utilization of solid/liquid biomasses"and"targeted construction of catalytic systems for functional magnetic materials",with the aim of producing FAME and AL mediated by catalysts directly,establishing an efficient catalytic system with functional magnetic materials,and enriching the multifunctional preparation and modification of magnetic materials,this study will investigate the catalytic transformation of non-edible oils and glucose,explore the preparation strategies of functional magnetic materials?such as acid,base,hydrophilicity,and hydrophobicity?with various targets,expound the key of the structure-activity relationship of magnetic catalytic materials,and research the kinetics of the reaction along with the reusability of the catalyst.Innovative results are discussed and listed as follows:?1?Fe₃O₄@SiO₂-SO₃H?S?,and Fe₃O₄@SiO₂-SO₃H?P?were prepared using thesolvothermal,and coprecipitation method respectively.According to the relative characterization manners,Fe₃O₄@SiO₂-SO₃H?S?was determined as the better-dispersed and uniform core-shell nanosphere.The relevant experiments have demonstrated that the morphology and structure of catalytic materials play an important role during the catalytic process.Fe₃O₄@SiO₂-SO₃H?S?is the single core-shell nanosphere with good dispersion that can be conducive to the contact between the substrate and the active site.On the contrary,the reunion of Fe₃O₄@SiO₂-SO₃H?P?is serious,indicating the solvothermal method is a better one.Upon using Fe₃O₄@SiO₂-SO₃H?S?catalysts in oleic acid and methanol esterification reaction,high biodiesel yield can be achieved.In addition,the thermal filtration experiment and the reusability results verified the heterogeneous catalytic behavior of the catalyst,showing a good stability accordingly.Accordingly,based on the above results,the solvothermal method for preparing a magnetic core-shell carrier is considered as a better choice.?2?Using the magnetic core-shell nanometer microsphere Fe₃O₄@SiO₂ prepared by the solvothermal method as a carrier,the magnetic core-shell solid acid catalytic materials including single B acid?FS-B-IL?,single L acid?FS-L-IL?and B-L double acid?FS-B-L-IL?were prepared by functionalizing and modifying Fe₃O₄@SiO₂ with three active kinds of acid IL,namely B acid IL,L acid IL,and B-L bi-acid IL,respectively.The synergetic effect ascribed to Br?nsted and Lewis acidities of FS-B-L-IL was the key reason to gain the best catalytic performance in obtaining a high Koelreuteria integrifoliola biodiesel yield of 93.7%.The main fuel properties of the obtained Koelreuteria integrifoliola biodiesel were also evaluated,which were comparable to specifications prescribed in the ASTM D6751 and EN 14214.It can be seen that the bifunctional catalyst FS-B-L-IL containing Br?nsted and Lewis acids,showed good catalytic activity in the preparation of biodiesel from crude Koelreuteria integrifoliola oil,and the fuel property of Koelreuteria integrifoliola biodiesel performed better.?3?Herein,to further upgrade and improve the magnetic core-shell material Fe₃O₄@SiO₂,basic polymeric ionic liquids?PILs?immobilized on the magnetic mesoporous core-shell carrier?Fe₃O₄@SiO₂@SBA-15?,FnmS-PILs,were synthesized through the facile radical polymerization and anion exchange methods,and were further utilized to catalyze transesterification of non-food feedstock crude Firmiana platanifolia L.f.oil?CFPO,acid value of 1.20 mg KOH/g?into biodiesel directly.The characterization results demonstrated that FnmS-PILs with uniform core-shell structure,moderate surface area?153.2 m²/g?,pore size?4.1 nm?,strong magnetism?13.6 emu/g?and relative higher basicity?2.3 mmol/g?exhibited high catalytic performance,giving a high biodiesel yield of 92.8 wt%.Besides,the relevant kinetic analyse,and reusability were also studied.All of the Firmiana platanifolia L.f.biodiesel properties were within the acceptable specifications of EN 14212 and ASTM D6751,showing its potential in biodiesel application.The research results in this chapter demonstrated that the FnmS-PIL material modified by alkaline PIL had better physicochemical properties and performed well in the application of preparing biodiesel from Firmiana platanifolia L.f.oil.?4?Eight kinds of organic-inorganic hybrid magnetic materials with different acidity and hydrophobicity were prepared by the control of various acid strength and hydrophobicity.It was found that acid strength played the most important role,and stronger hydrophobicity also provided strong support for good catalytic performance.The detailed characterization results demonstrated that the FnmS-PIL?1a,C8?core-shell structure catalyst had a high number of acid sites?2.14 mmol/g?,strong acid strength?strong electron-withdrawing anion CF₃SO₃^-effect,-8.2<H₀<-5.6?and strong hydrophobicity?water contact angle,115.4°?.Fnms-PIL?1a,C8?performed better in both catalytic oleic acid esterification and one-pot preparation of biodiesel from Euphorbia lathyris L.oil,and its good water resistance further clarified the important role of strong hydrophobic regulation.The kinetic study indicated that the catalytic esterification system was suitable for the first-order reaction and showed a low activation energy of 39.2 kJ/mol.The reusability of the FnmS-PIL?1a,C8?catalyst was good,and its physicochemical structure was found to keep stable.In addition,the fuel performance of Euphorbia lathyris L.biodiesel is in line with the American ASTM D6751 and European EN 14214 standards,highlighting its great potential as a non-food oil feedstock for biodiesel.According to the results derived from this part,we found a novel and feasible method which can properly regulate the key properties of magnetic core-shell porous materials,such as acidity and hydrophobicity.?5?Based on the poor solubility between oil and methanol,and the important changes in biodiesel yield by the effective regulation of the ratio of B/L acid sites,the magnetic core-shell porous spheres solid acid catalysts including FnmS-PIL?0.5?,FnmS-PIL?1?and Fnm S-PIL?2?were designed and synthesized with a controllable proportion of B/L double acid site.Using the biomass-derived tetrahydrofuran bearing a moderate polarity as the co-solvent along with the important FnmS-PIL?1?catalyst showing a good core-shell porous microsphere morphology?the porous structure can provide more active sites,the homogeneous sphere is conducive to the contact between the active site and the substrate?,the appropriate B/L ratio,the large specific surface area of 169 m²/g and the homogeneous pore diameter of 3.5 nm,the best performance in the preparation of biodiesel from Euphorbia lathyris L.oil was demonstrated.Furthermore,concerning the catalytic preparation of ML which is a biomass ester fuel come from the wider range of glucose,42.3%yield of ML was prepared under the reaction conditions of 180°C for 6 h,indicating its certain application universality.The above results showed that the as-synthesized magnetic core-shell porous spheres can not only provide convenient magnetic separation properties but also can improve the mass transfer efficiency.Moreover,the biomass-derived co-solvent tetrahydrofuran can improve the solubility of alcohol and oil,thus increasing the yield of biodiesel.?6?From the economic point of view,the montmorillonite-based magnetic solid B-L acid catalyst using a facile,and low-cost strategy was designed and synthesized.The yield of Jatropha curcas L.biodiesel produced by simultaneous esterification and transesterification of crude Jatropha curcas L.oil was determined to be 92.9%.Besides,concerning the catalytic preparation of ML from glucose,the maximum yield of 46.8%for ML was obtained at 180°C within 8 h.The reusability and thermal filtration tests showed that the catalytic manner is a heterogeneous behavior and the reusability is good.Through this part of the research work,we developed a preparation strategy for fabricating the magnetic montmorillonite composite solid acid catalyst having economical efficiency,simplicity,and multifunctionality.