Study On The Effect Of One Dimensional Nanostructure Catalyst On Photocatalytic Reduction Of Gas Phase CO₂

The global energy crisis and environmental pollution caused by the global economic development have become the two major problems for human beings.The consumption of fossil energy has sharply increased the content of CO₂ in the atmosphere,and Such situation has caused a series of environmental problems such as greenhouse effect.In the past studies,the use of photocatalyst to reduce CO₂ into hydrocarbon fuels,which mimic the technology of plant photosynthesis is an ideal way to reduce CO₂ concentration and achieve energy recycling.TiO₂ nanomaterials have important applications in the field of photocatalysis because of their strong oxidation resistance,non-toxic,environmentally friendly,cheap,pollution-free and so on.In this paper,we use the traditional hydrothermal synthesis to fabricate TiO₂ nanorod array films,and using XRD,SEM-EDS,TEM,UV-vis and XPS to detect the crystal structure,morphology and chemical state of the prepared catalysts.The preparation and design of micro fluidic reactor were used the photolithography technology.At the same time,the catalysts were used to reduce the gas phase CO₂ on the basis of micro fluidic reactors.The concentrations of the products were detected by gas chromatography.The main research contents are as follows:1)TiO₂ nanorod array films were prepared by traditional hydrothermal method,and different concentration of Cu²⁺ were doped on the basis of TiO₂ nanorod array films by using continuous ultrasound assisted cation adsorption method.The photocatalytic reduction gas phase CO₂ was carried out by using the prepared catalysts combined with plate micro fluid reactors.In the course of experiment,the effects of different Cu²⁺ concentration,CO₂ flow rate and reaction temperature on the reaction performance were studied,among them,the UV light source was kept at 365 nm,CO₂ and water vapor ratio was remained at 10:1.The results show that the yield of methanol and ethanol was the highest when the mass fraction of Cu²⁺ ion was 1.5wt.% and the CO₂ flow rate was 2ml/min,namely the catalytic performance was the best at that condition,and the yield of methamol and ethanol were 24.42 ?mole/g-cat·h ? 47.25 ?mole/g-cat·h respectively.The catalytic rate increased with the increase of temperature.The addition of Cu²⁺ ions can not only effectively inhibit the generation of photogenerated electron hole pairs,but also has a selective formation of catalytic products.2)In order to further enhance the absorption intensity of the visible light,the CdS quantum dots were used to sensitized the nanorod array films on the basis of the 0.02 M Cu²⁺/TiO₂ nanorod arrays films.The organic solution was used to dissolve the sensibilizers under the successive ionic layer adsorption and reaction method.Among them,the amount of CdS quantum dots was determined by the number of cycles.Experimental studies on photocatalytic reduction of CO₂ were carried out on flat plate microfluidic reactors under simulated sunlight.The results show that the catalytic efficiency was the highest when the number of cycles was 2 and the CO₂ flow rate was 4ml/min and the yield of ethanol was 70.27 ?mole/g-cat·h.The results show that CdS quantum dots could promote the production of ethanol under visible light.3)The preparation of inverted convex microfluidic reactors on the basis of flat micro fluidic reactor,and the photocatalytic experiments were carried out combining the C2 CdS-Cu²⁺/TiO₂.The diameter,spacing and height of the micro convex plate were analyzed by orthogonal test.The results show that the catalytic effect was the best when the diameter,spacing and height were 500?1000 and 200?m respectively.Results display that the height of the staggered micro-pillars was the greatest influencing factor,the spacing was the second,and the diameter of the micro convex plate was the least.The experimental results show that when the diameter,spacing and height of the micro-pillar were 500,1000 and 150?m,CO₂ flow was 3.5ml/min,the ethanol yield was 95.19 mol/g/h.The results show that the addition of the staggered micro-pillars can promote the flow of reactants in the reactor,the supply of the reactant on the surface of the catalyst layer and the desorption process of the reaction product on the surface of the catalytic layer.