Preparation Of Cupoous Oxide Based Composite Catalyst And Application To P-nitrophenol Reduction

It is well known that inorganic nanocrystals are the benchmark model of nanotechnology,and its tunability of optical properties and the unity of specific phases have been a concern for a long time.Copper oxide?Cu₂O?is a metal oxide semiconductor that is widely used not only in solar energy conversion but also organic catalysis.It also has a good application prospect in both aqueous phase catalytic reactions and gas catalytic reactions.To explore the nanoscale Cu/Cu₂O/CuO system,we developed a method for preparing a series of highly uniform Cu₂O monodisperse nanocrystals.In addition,a variety of synthetic methods such as grinding,hydrothermal,sedimentary precipitation and solvothermal methods were successfully used to prepare cuprous oxide-based composites with different morphologies.Through the morphology control,catalytic materials with different properties were obtained.In the related research on the reduction of nitrophenols by Cu₂O composites,not only exploding the reduction of p-nitrophenol?4-NP?to p-aminophenol?4-AP?,but also analyzing the activity and stability of the catalyst.Finally,through a series of methods of the catalytic reduction reaction mechanism and by comparing with other researchers'test results,a catalyst with high catalytic efficiency and recyclability is obtained.Then it is converted to paracetamol?APAP?by a self-assembling device.Direct conversion from 4-NP to APAP drugs was completed in one step,while other researchers did not report related studies.The research content of this paper can be summarized as the following aspects:1.We report the preparation of a series of Cu₂O/SrTiO₃ and Cu₂O/Cu/SrTiO₃nanocomposites by Cu⁺in situ reduction mathod during the reaction.The catalytic performance of the composite was evaluated by converting a high concentration of4-NP to 4-AP in the presence of NaBH₄ through the tests of the reduction rate and cycle stability.Cu₂O/Cu/SrTiO₃ also exhibited higher reducing activity and reusability stability with continuous batch mode under continuous flow conditions.Amplification experiments show that 4-NP?5 L,0.01 mol/L?can be continuously converted to 4-AP above 30 mg under continuous flow conditions,far better than other literature reports.The catalytic mechanism was proposed that Cu^0/Cu¹⁺as a shuttle for hydrogen and electron transfer could promote the reducing ability,and SrTiO₃ as a protective agent to encapsulate tetrahedral Cu₂O could achieve a significant increase in catalyst stability.It is proved that Cu₂O/Cu/SrTiO₃ three-phase composite is a better high activity catalytic composite.Current research indicates that the prepared nanocomposites may not only be an effective and potential material for converting nitroaromatics to aminoaromatics at the laboratory level,but also have certain prospects for larger industrial applications.2.Three different morphologies of cuprous oxide and cerium oxide composite catalysts were successfully prepared by simple grinding method,hydrothermal method,sedimentation precipitation method and solvothermal method for the study of reduction of p-nitrophenol.The three composite catalysts are:Cu₂O/CeO₂,Cu₂O@CuO/CeO₂ and Cu₂O@CeO₂,respectively.The catalytic activity was compared by reducing the same concentration of p-nitrophenol.At the same time,not only the phase analysis of the catalyst was carried out,but also the morphology of the sample was discussed by TEM and SEM.Finally,the crystal growth mechanism of the composite was discussed and described by its reaction materials and formation conditions.The reduction of p-nitrophenol can be reduced in traditional way using three different catalysts.Finally,through electrochemical properties,fluorescence intensity comparison,and EPR oxygen vacancy analysis,it confirmed the cerium oxide is used as an oxygen vacancy adsorption site,and the possible catalytic reduction mechanism of cuprous oxide as a reduction site is predicted.3.We designed and prepared a series of core-shell Cu₂O@CeO₂ catalysts using a simple solvothermal method at room temperature and used thm to complete APAP batch preparation by 4-NP.First,4-NP was converted to 4-AP rapidly and highly selectively on a Cu₂O@CeO₂ catalyst and then APAP was produced with the addition of acetic anhydride.A one-step process for preparing APAP was completed.In addition,APAP was characterized by IR,LC-MS and H NMR techniques,and these characterization methods all showed higher purity of APAP.The mechanism of catalyst is obtained by XPS,PL,EPR and other analysis methods.CeO₂ provides oxygen vacancies as reaction adsorption sites.Cu₂O and BH₄⁺dispersed in CeO₂spherical shells provide hydrogen source,CeO₂ as electronic medium and spherical shell,provides a larger cont act area and protection means so that the stability of the catalyst and the purity of the product are greatly improved.Also,we hace constructed a equipment for the small-scale generation ofAPAP.Summarily,a new idea for the treatment of large amounts of p-nitrophenol is provided with a designed highly active catalyst.