Research On Photocatalytic Performance For Hydrogen Production From Glycerol Solution Based On Modified CNTs-TiO₂ Composite

The energy crisis and environmental pollution have become two important factors restricting economic development and social progress. In recent years, the application of the clean hydrogen energy has attracted extensive attention. Glycerol, soluble in water, is the main byproduct of biodiesel. The rapid development of the biodiesel industry has brought the situation that glycerol is excess and difficult to recycle. However, conventional methods such as steam reforming partial oxidation and auto-thermal reforming need harsh reaction conditions and high cost. Therefore, this paper focused on the photocatal ytic performance for hydrogen production from glycerol solution based on CNTs-TiO₂ composite, and inves tigate d catal ytic acti vit y of modified cat al ysts. The main research contents and conclusions are as follows:CNTs-TiO₂ composite catalyst was prepared by sol-gel method, and then the catalyst preparation conditions were discussed. The effects of different preparation conditions such as the amount of water, the amount of acid and dosing ratio of carbon nanotubes on the catalytic activity were analyzed. The results showed that the optimal preparation conditions of catalyst CNTs-TiO₂ were obtained. At that point, the catalyst would be of the highest activity, namely the hydrogen production efficiency is 18.5 μmol/（h?gcat）.Then nitrate acidification and platinum doped were respectively co nducted on the basis of CNTs-TiO₂ in order to improve the photocatalytic activity. The effects of preparation conditions on the catalytic activity were studied respectively. And then both catalyst acidulated CNTs-TiO₂ and catalyst Pt-CNTs-TiO₂ with the highest activity were obtained by optimization. The influences of reaction conditions including the concentration of glycerol, the reaction temperature and the p H value on the catalytic effect were analyzed to ensure the optimal reaction conditions. The resul ts suggested that the maximum of hydrogen production efficiency is 314.8 μmol/（h?gcat） for catalyst acidulated CNTs-TiO₂, and the maximum of hydrogen production efficiency is 3 057.6 μmol/（h?gcat） for catalyst Pt-CNTs-TiO₂. Characterization results indicated that catalysts had already formed the crystal structure and optical absorption of them shifted to longer wavelengths.In order to further improve the photocatalytic activity, nitrate acidification combined with platinum doped was used to modify catalyst CNTs-TiO₂. The effects of preparation conditions on the catalytic activity were investigated and catalyst acidulated Pt-CNTs-TiO₂ with the highest activity were obtained. Photocatalytic hydrogen production effects under different reaction conditions were explored to ascertain the optimal reaction conditions. The results indicated that the maximum of hydrogen production efficiency is 5 636.2 μmol/（h?gcat） under the optimal conditions. The comparative analysis of reaction and characterization results between catalysts before and after modification indicated that the activity of modified catalysts increased significantly, moreover modified catalysts had already formed the crystal structure, optical absorption of them shifted to longer wavelengths and surface acidity of them increased.