TiO₂/Al₂O₃ 复合载体的气体传质模拟与结构优化

In order to optimize the structure of TiO₂/Al₂O₃ composite support for the preparation of high flux all-silica Deca-Dodecasil 3R(DD3R) zeolite membrane, a gas mass transfer model based on viscous flow and Knudsen diffusion was established, and the required parameters of the model were obtained through experiments. The effects of operating conditions and structural parameters on gas penetration in the composite support were systematically examined. The calculated results of single-component gas flowrate show remarkable agreement with the experiments and the model reliability was verified. The simulation results indicate that increasing pressure or decreasing temperature could inhibit the influence of Knudsen diffusion in gas permeation. Furthermore, the mass transfer resistance is mainly concentrated in the TiO₂ layer and sponge-like layer when CO₂ permeates through the multi-layer asymmetric structure of the composite support. Finally, based on the existing works of DD3R zeolite membranes, contour maps of the ratio of CO₂ permeance between the composite support and the zeolite membrane were established to reveal the synergistic effect of the structural parameters (pore size and layer thickness of the TiO₂ layer and sponge-like layer) on gas permeance of TiO₂/Al₂O₃ composite support.