Preparation Of Spinel Aluminate Powders And Their Photocatalytic Reduction Activity Of CO₂

Over the past years,a serious contemplation has revealed the need to resolve two major complications:global warming due to rising levels of atmospheric carbon dioxide(CO2) and the alarming consumption of energy resources. Photocatalytic reduction of CO2technology is considered to be the most promising method in solving the problem of greenhouse gas, and realize the recycling of carbon resource. In this paper, using spinel aluminate (COAl2O4, ZnAl2O4CuAl2O4) as catalysts,and the catalysts were placed in the gas-solid-liquid phase reaction system to have photocatalytic reduction of CO2/H2O to formic acid.Using organic precursor method to prepare a series of spinel aluminate (CoAl2O4, ZnAl2O4,CuAl2O4) catalysts,and the catalysts were chatacterizated by TG-DTA/DSC,FTIR,XRD,Uv-Vis DRS,SEM, then applied in the catalytic reduction of CO2/H2O system. Characterization results showed that, after being calcinated,besides CUAl2O4,CoAl2O4and ZnAl2O4catalysts are formed directly spinel phase,and the particle size of three catalysts are about (10-30) nm. The calcined CuAl2O4appeared CuO mesophase, and was not completely disappear in the condition of900℃calcinated. Under uv irradiation, the catalyst was placed in a quartz glass tube and stirred suspension of its photocatalytic reduction of CO2.AS the results showed that:ZnAl2O4catalyst particles were dispersed evenly,and had a strong response to uv light,also had excellent activity of photocatalytic reduction of CO2,CoAl2O4catalyst followed. The photocatalytic reduction of CO2activity of CuAl2O4was worst because of the weak uv light response performance,and having the most serious reunion of CuAl2O4.The technological conditions for synthesis of ZnAl2O4with organic precursor method was studied, and the reaction conditions of photocatalytic reduction of CO2was optimized. The results showed that:The best calcination temperature of ZnAl2O4was900℃, calcination time was4h. When the flow rate of CO2was200mL/min, the dosage of catalyst was1.5g/L, the reaction temperature was60℃, reaction time was8h, the yield of formic acid could reach843.26μmol/g (the amount of formic acid generated in ZnAl2O4catalyst material per gram to meter). And the mechanism of MAl2O4aluminate catalysts photocatalytic reduction of CO2were explored.Photocatalytic reaction conditions had a certain influence on the experiment and research shows that the calcination temperature of catalyst, catalyst dosage, reaction temperature, CO2 flow, all havd an impact on response, we will strictly control the various factors in the process of experiment.