CaO/ZrO2固体碱催化水解CFC-12的研究

Catalytic Hydrolysis of Dichlorodifluoromethane （CFC-12） over CaO/ZrO2 Solid Base Catalyst

采用沉淀过饱和浸渍法制备CaO/ZrO2固体碱催化剂,通过XRD、SEM、EDS、N2吸附-脱附、FT-IR和CO2-TPD表征手段对催化剂进行表征,同时研究了催化剂焙烧温度、催化水解温度、水蒸气浓度与总流量对CFC-12转化率的影响.结果表明,在焙烧温度为500℃、催化水解温度为400℃、水蒸气浓度为25%、总流量为5mL/min时CFC-12的转化率最高,达到95.80%,主要产物为HCl、HF和CO2,副产物为CFC-13.表征结果表明其为典型的介孔材料,并且纯度较高,经过焙烧后CaO和ZrO2形成了固溶体,500℃焙烧的催化剂具有较高的比表面积和孔容,焙烧温度过高催化剂会烧结成块,孔结构遭到破坏.CO2-TPD表征结果表明催化剂的活性中心为碱,并且高的焙烧温度会降低其碱性.

CaO/ZrO2 solid base catalyst was prepared by precipitation supersaturation impregnation method. The catalyst was characterized by XRD, SEM, EDS, N2 adsorption-desorption, FT-IR and CO2-TPD. The effects of calcination temperature, hydrolysis temperature, water vapor concentration and total flow rate on CFC-12 conversion were studied. The results showed that the CFC-12 conversion could reach 98.50% by using CaO/ZrO2 solid base as the catalyst at calcination temperature of 500℃, a hydrolysis temperature of 400℃, a water vapor concentration of 25% and a total flow rate of 5 mL/min and the main hydrolysis products were HCl, HF and CO2 and the by-product was CFC-13. The characterization results showed that CaO/ZrO2 solid base catalyst was a typical mesoporous with high purity. After calcination, CaO and ZrO2 formed a solid solution. The calcined catalyst at 500℃ had a high specific surface area and pore volume. If the calcination temperature was too high, the catalyst would be sintered into a block and the pore structure was destroyed. CO2-TPD characterization results indicated that the active center of the catalyst was base and a high calcination temperature lowered its basicity.