The dehydrogenation of propane to propylene is endothermic reaction will generate hydrogen, while the hydrogenation of CO2 to light olefins is exothermic reaction with hydrogen as reactant. Using the CO2 hydrogenation reaction to consume the hydrogen from the propane dehydrogenation reaction, which is more beneficial to propylene generation. Thus, a promising approach of coupling propane with CO2 to produce propylene was proposed. A simple wetness impregnation method was used to prepare the In/HZSM‐5 composite catalyst for this coupling reaction. It was characterized by means of XRD, SEM, TEM, H2‐TPR, NH3‐TPD, XPS, TG, and N2 isothermal adsorption‐desorption. Effects of indium loading, feed volume ratio of propane to CO2, reaction pressure and temperature on the coupling of propane with CO2 to propylene were investigated in a fixed‐bed reactor. When the mass content of indium is 12%, the feeding volume ratio of propane to CO2 is 1 : 4, the reaction pressure is 0.3 MPa and the reaction temperature is 580 °C, the propylene selectivity is 71.41%, as well as the conversion per pass of propane and CO2 is 17.74% and 5.08%, respectively.
The ZnIn/HZSM-5 catalyst was prepared by the wetness impregnation method, and the structure of catalyst was characterized by XRD, SEM, TEM, H2-TPR, NH3-TPD, XPS, TG, and N2 adsorption–desorption and then investigated in the coupling of propane with CO2 to propylene. It is found that the addition of Zn species is beneficial to the dispersion of In2O3 over HZSM-5, which plays an important role in propene formation, and adjusts the acidity distribution of In/HZSM-5 catalyst, as well as significantly improves the activity of In/HZSM-5 catalyst. The selectivity of propylene is 68.21% in the coupling of propane with CO2 over ZnIn/HZSM-5 catalyst when the time on stream (TOS) is 2 h, reaction temperature is 580 °C, reaction pressure is 0.3 MPa, C3H6:CO2:N2 = 1:4:5, catalyst mass is 0.2 g, and space velocity is 6000 mL gcat−1 h−1. However, the selectivity of propylene is only 63.33% and 0.25% in the propane dehydrogenation or CO2 hydrogenation reaction, respectively. The ZnIn/HZSM-5 catalyst showed a higher stability with only 0.80% conversion drop after three cycles.
Hierarchically porous P substituted HZSM‐5 (H[P, Al]‐ZSM‐5‐AT‐0.05 M ) was successfully synthesized by isomorphous substitution method with introduced P atoms into ZSM‐5 zeolite frameworks followed by alkali treatment. H[P, Al]‐ZSM‐5‐AT‐0.05 M was characterized by XRD, ICP‐OES, SEM, FT‐IR, N2 adsorption‐desorption, NH3‐TPD, XPS, Py‐IR, and TG‐DTA, respectively. The surface area, pore volume, particle size and P/Al (molar ratio) are 328 m2.g−1, 0.23 cm3.g−1, 563 nm and 0.027, respectively. The catalytic performance of H[P, Al]‐ZSM‐5‐AT‐0.05 M in coupling reaction of methanol with 1‐butene was investigated in the fixed‐bed reactor. On the condition of reaction temperature at 500°C under atmosphere pressure, the main product is propylene with the selectivity and yield of 33.7% and 31.0%, respectively. Hydrogen transfer index was calculated to 0.24. Moreover, its diffusion limitation was investigated with the self‐etherification of benzyl alcohol reaction. The value of Thiele modulus (η
) and effectiveness factor (ϕ
) are 0.08 and 16.9, respectively.
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