| Abstrakt: |
Granule oxides of ZrO2–ZnO–CeO2are integrated with nano-sized SAPO-34 zeolites to form tandem catalyst, which is effectively utilized in catalysis of CO2hydrogenation to produce light olefins. Then, Nano-sized SAPO-34 zeolite of particle diameter about 100 nm is synthesized by using morpholine-treated SAPO-34 as seed of crystal and taking morpholine as the sole template. Ternary ZrO2–ZnO–CeO2oxides with various CeO2contents are prepared by traditional co-precipitation method. The catalysts were characterized by XRD, SEM, TEM, N2adsorption–desorption, H2-TPR, NH3-TPD, CO2-TPD, XPS and in situ DRIFT measurements. The introduction of CeO2into Zr-Zn oxides efficiently increases the oxygen vacancies to possess the stronger adsorption capacity of CO2and H2. Nano-sized SAPO-34 has a larger specific surface area and suitable amount of medium to strong acidic sites. CO2conversion and products distribution are strongly dependent on the oxide composition and morphology of SAPO-34 zeolite. When the atomic ratio of Zr:Zn:Ce is 4:2:1, the mass ratio of metal oxide to zeolite is 1:1, under the reaction temperature of 350 °C, pressure of 2.6 MPa, CO2:H2= 1:3 (molar ratio), GHSV = 6000 mL/(gcath) and the tandem catalyst dosage of 0.5 g, the CO2conversion is 24.1%, the selectivity and yield of light olefins are 86.3% and 20.8%, respectively, and the catalytic lifetime is about 425 min. |
Full text from SpringerLink