Preparation Of Palladium Catalysts Immobilized On Modified Oyster Shell And Their Catalytic Performance In Homocoupling Reaction Of Olefins

The development of palladium catalyzed cross-coupling reaction is rapid.Richard Heck,Ei-ichi Negishi and Akira Suzuki were awarded the 2010 Nobel Prize in chemistry for their outstanding contribution in the field.This fully demonstrat the importance of homogeneous palladium catalysis in organic synthesis chemistry.However,the cost and efficiency of homogeneous palladium catalysis had limited the development of industrial applications.The heterogeneous palladium catalyst have the advantages of easy separation and recovery,high recycling efficiency,non-toxic and pollution-free,environment-friendly,etc.Therefore,heterogeneous palladium catalysis in organic synthesis is a challenging and strategic research topic.How to make full use of existing resources,modify palladium catalysis efficiently and realize environmental friendliness at the same time,is worthy of our attentions.Hydroxyapatite(HAP;Ca₁₀?PO₄?₆?OH?₂)is widely used as supported material due to special surface structure.It has potential application for palladium-catalyzed reaction.In this project,the waste oyster shell is used as the calcium source to prepare hydroxyapatite carrier,and the nano hydroxyapatite supported palladium catalyst is designed and synthesized,which is applied to the multi-phase catalytic reaction.The effect of the structure of hydroxyapatite on the activity of heterogeneous palladium catalyst was studied.The main purpose of this project are to find an ideal carrier for palladium immobilization through the modification of oyster shell,develop high-efficiency and low-cost heterogeneous palladium catalyst,and overcome the shortcomings of the homogeneous palladium catalyst,such as non reuse,high cost and environmental harm.At the same time,The catalytic performance of palladium catalysts immobilized on modified oyster was studied in homocoupling reaction to olefins.The application of heterogeneous palladium catalyst in olefin coupling reaction has not only improved the synthesis method of some important compounds,but also realized the high value utilization of oyster shell.The specific contents of this paper are as follows:?1?The method of Wacker oxidation was studied by using oxygen as a single oxidant,Pd?OAc?₂as catalyst and trifluoromethane sulfonic acid as additive.In water/N,N-dimethylformamide mixed solvent,the oxidation of alkenes to methyl ketones was realized.?2?A new method of organic synthesis of 1,4-diphenyl-1,3-butadiene with oxygen as a single oxidant and Pd?OAc?₂as a catalyst was attempted.It was the first time to synthesize 1,4-diphenyl-1,3-butadiene through dehydrogenation homocoupling of alkenes in H₂O/DMF reaction medium.?3?Taking Zhanjiang waste oyster shell as the calcium source,a series of pretreatment was carried out to remove the impurities and retain its biomass structure.Using Na₄P₂O₇as the phosphorus source,the calcium deficient?non stoichiometric?nano hydroxyapatite?HAP?was prepared by hydrothermal reaction,and its structure was characterized.Compared with the XRD standard spectrum,it was basically consistent.Pd/HAP catalysts were prepared by impregnation method.The catalysts were analyzed by X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,inductively coupled plasma mass spectrometry?ICP-MS?.?4?Pd/HAP catalyst is used to catalyze the oxidative dehydrogenation coupling reaction to olefins.The results show that Pd/HAP has high catalytic activity for the oxidative dehydrogenation coupling reaction to olefins.The catalyst can be recycled and reused by simple operation of centrifugation and washing,and can be reused for more than 6 times,but the yield is still not significantly reduced.The catalyst not only solves the problems of waste oyster shell resources and environmental pollution,but also promotes the green and efficient oxidative dehydrogenation of olefins.