粉煤灰基Y型分子筛的制备及其对CO2加氢性能的研究

Preparation of Fly Ash-based Y-type Molecular Sieves and Their Performance for CO2 Hydrogenation

中文关键词:  粉煤灰  分子筛  CO₂加氢  固废物利用

英文关键词:fly ash  molecular sieve  CO₂ hydrogenation  solid waste utilization

中文摘要:

      以粉煤灰为原料制备Y型分子筛, 并探究其CO₂加氢活性. 采用化学焙烧法活化粉煤灰, 以Na₂CO₃作为化学活化剂, 探究焙烧温度、焙烧时间、粉煤灰与碳酸钠的质量比对活化粉煤灰的影响, 实验结果表明在焙烧温度800 ℃、焙烧时间2 h、粉煤灰与Na₂CO₃质量比为1.0∶0.8条件下, 粉煤灰焙烧后产物以霞石为主. 以洗涤后产物为原料, 采用水热合成法制备Y型分子筛, 探究HCl/SiO₂比、晶种加入量、H₂O/SiO₂比、水热温度、水热时间对分子筛结晶度影响, 在HCl/SiO₂=2.7, 晶种加入量为6%, H₂O/SiO₂=80, 水热温度100 ℃、水热时间12 h所制备的Y型分子筛结晶度最高. 将所制备的Y型分子筛进行CO₂加氢实验, 实验结果表明在反应温度600 ℃, 反应压力为4.0 MPa条件下, CO₂转化率达到60%, CH₄选择性达44.9%.

英文摘要:

      Y-type molecular sieves were prepared from fly ash and their CO₂ hydrogenation activity was investigated. Chemical roasting method was adopted to activate fly ash, and Na₂CO₃ was used as the chemical activator to investigate the effects of roasting temperature, roasting time, and the mass ratio of fly ash to sodium carbonate on the activation of fly ash, and the experimental results showed that under the conditions of roasting temperature of 800 ℃, roasting time of 2 h, and the mass ratio of fly ash to Na₂CO₃ of 1.0∶0.8, the products of the roasting of fly ash were dominated by chalcopyrite. The Y-type molecular sieves were prepared by hydrothermal synthesis method using the washed products as raw materials, and the effects of HCl/SiO₂ ratio, crystal seed addition, H₂O/SiO₂ ratio, hydrothermal temperature, and hydrothermal time on the crystallinity of the molecular sieves were investigated, and the Y-type molecular sieves prepared at the conditions of HCl/SiO₂=2.7, crystal seed addition of 6%, H₂O/SiO₂=80, hydrothermal temperature of 100 ℃, and hydrothermal time of 12 h were found to have the highest crystallinity. The prepared Y-type molecular sieves were subjected to CO₂ hydrogenation experiments, and the experimental results showed that the CO₂ conversion rate reached 60% and the CH₄ selectivity reached 44.9% under the conditions of reaction temperature of 600 ℃ and reaction pressure of 4.0 MPa.