Preparation Of Supported Titanium Dioxide P25 Catalyst And Its Photocatalytic Nitrogen Fixation Performance

Since the last century,the rise of synthetic ammonia industry has brought the dawn to solve the food crisis caused by the world population growth.Today,80 percent fertilizers come from the ammonia industry?Haber-Bosch reaction?.The reaction process consumes plenty of energy and emits a lot of CO₂.According to statistics,the total amount of natural gas consumed by the ammonia industry each year accounts for 3%of the global total consumption,the energy consumption accounts for 1%of the world's total energy consumption,and the greenhouse gas emissions are up to 1%of the world's total emissions.Therefore,the development of sustainable ammonia technology is undoubtedly one of the major problems to be solved in the scientific research field in the 21st century.Many researchers try to design the catalysts and use photocatalysis,thermocatalysis,electrocatalysis,photoelectrocatalysis and other ways to synthesize ammonia under mild conditions.Photocatalysis is similar to the natural photosynthesis process,both of which use solar energy to carry out heterogeneous catalytic reactions under light irradiation at room temperature.In this paper,photocatalytic technology is introduced into ammonia synthesis process,which can make use of the ideal green solar energy to produce NH₃ via reaction N₂?g?+3 H₂?g??2 NH₃?g?without additional heat input at room temperature.The main research contents are as follows:In Chapter 2,different mass ratios?0%,1%,2.5%,6%,10%?of noble metal Ru supported P25 photocatalysts were prepared with RuCl₃ aqueous solution as precursor and titanium dioxide P25 as carrier.HRTEM,XRD,FTIR,Raman and other characterization techniques were used to analyze the material structure and determine the size and dispersion state of the catalysts.UV-Vis,PL,EIS and other detection methods were used to verify the improvement of carrier separation efficiency of the semiconductor catalyst loaded with noble metal Ru.Through the quantitative analysis of the products of photocatalytic nitrogen fixation reaction by colorimetry and ion chromatography,it proved that the nitrogen fixation performance of the catalyst improved after the metal Ru was supported and the ammonia yield of the catalyst was as high as 419?mol/L/g after 8 hours of light reaction.In Chapter 3,the two-dimensional layered material MXene was obtained by HF etching with MAX as the precursor.Different mass ratios?0%,2%,4%,6%,8%?of MXene supported P25 photocatalysts were prepared using classic photocatalyst titanium dioxide P25 as carrier to investigate its nitrogen fixation performance under ambient temperature and pressure.The morphological and structural characteristics of MXene on P25 were determined by SEM,XRD,FTIR,Raman and other characterization methods.UV-Vis,PL,EIS and other test methods were used to prove that the catalyst carrier separation efficiency improved after loading MXene.The determination of ammonia production by ion chromatography showed that MXene was helpful to enhance the performance of nitrogen fixation.With the increase of the load of MXene,the nitrogen fixation performance improved.When the load reached 6%,the nitrogen fixation performance was optimal,and the yield reached 150?mol/g/L.