A Study On The Synthesis Of Biomass-based Linear Alkanes And Cyclic Oxygen-containing Compounds

The problem of energy shortage and rapid environmental deterioration caused by the rapid consumption of fossil energy has become a major and critical problem faced by mankind in recent years.In order to reduce the excessive dependence on petroleum and alleviate environmental problems such as the greenhouse effect,the synthesis of alternative fuels based on biomass sources and the development of sustainable biomass fine chemicals have gradually attracted widespread attention.Among them,a large number of studies have been done to obtain long-chain alkane fuels and biomass platform molecular compounds to synthesize cyclic compounds through the deoxygenation of oils.In this paper,for the synthesis of linear fuels and cyclic compounds,based on decarboxylation and oxidation reactions,an efficient and stable catalyst is designed and prepared,reaction conditions are optimized,and the reaction mechanism is explored.The main research contents and conclusions include:（1）Using the fat model compound stearic acid as the raw material,using double metal cyanide to prepare carbon-coated bimetallic Fe Ni alloy at different temperatures through the in-situ carbonization reduction strategy as a catalyst,under the condition of no hydrogen and no solvent Catalytic decarboxylation of stearic acid to obtain long-chain alkanes.It is found that the size of the alloy and the thickness of the carbon shell can be easily adjusted by changing the temperature.Compared with single-metal Fe/C and Ni/C catalysts,alloy catalysts show significant improvements in the conversion of stearic acid and the selectivity of heptane.ATR-infrared spectroscopy shows that inserting inert iron elements into nickel nanoparticles can promote the adsorption of carboxylic acid generating groups but inhibit the adsorption of hydrocarbon groups.The synergistic effect of Fe and Ni elements promotes the direct decarboxylation of stearic acid and inhibits the CC cracking reaction.Among t hem,after studying various alloy catalysts,Fe Ni@C-800 showed the best catalytic performance with a conversion rate of 99.9%.The separation of stearic acid and the selectivity to heptane are 76.8%.In addition,the protection provided by the catalyst by carbon can still remain stable,and has a protective effect on the leaching of metals.This work not only provides a powerful reaction system for the decarboxylation of stearic acid,but also demonstrates a noble metal replacement catalyst based on a convenient carbonation reduction strategy.（2）CeO₂,MoO₃ and Ce-Mo-O metal oxide catalysts were prepared by a simple sol-gel method.Among them,MoO₃ has high activity for BTO coupling,while Ce-Mo-O catalyst can further oxidize the coupled dimer to hydroxybenzodiquinone.Through a series of characterizations such as TEM,O₂-TPO,H₂-TPR,we found that the doping of CeO₂ by MoO₃ not only makes Ce-Mo-O nanoparticles（2-5 nm）smaller than MoO₃（200 nm）and CeO₂（20 nm）has become smaller,and the oxidation-reduction ability has also been greatly improved.This is consistent with the experimental results ofO₂-BTO.The Ce-Mo-O catalyst with stronger oxidizing ability can further oxidize the dimer to hydroxybenzoquinone.We guess that the doping of Mo makes the CeO₂ surface rich in oxygen vacancies,thereby enhancing the oxidation ability of Ce-Mo-O.In addition,we also did a performance cycle test of Ce-Mo-O.After 4 cycles,the BTO oxidation reaction still has a higher conversion rate and selectivity.Compared with acid-base homogeneous catalysts,the reaction conditions are mild.,The catalyst is cheap and easy to obtain and can be recycled for many times,and it is easy to industrialize.In addition,the hydroxybenzodiquinone fine chemicals in this chapter are synthesized based on biomass platform compounds,which reduces excessive dependence on petroleum and environmental pollution,conforms to the concept of sustainable development,and provides a feasible way for the high-value utilization of biomass cyclic compounds.Ideas.