Preparation and Performance Evaluation of an Asymmetric Polyimide Membrane Used in a Novel Solvent Absorption-Membrane Desorption CO2 Capture

Rectisol processes, as traditional precombustion capture processes, have been plagued by high energy consumption and secondary environmental pollution. A new organic solvent absorption-membrane desorption method is expected to solve the above problems, but there is a huge challenge in developing organic solvent-resistant membranes. Although polyimide with good resistance, high flux, and high selectivity is the best choice for membrane materials, due to the high viscosity and easy curing characteristics of polyimide casting solution, it is not easy to prepare a stable membrane by conventional membrane preparation methods such as scraping, casting, and so on. In this paper, a new preparation method of an asymmetric solvent-resistant polyimide CO2 permeation membrane based on the spin-coating method was developed. Using a cellulose acetate ultrafiltration membrane as the support layer and polyimide as the active layer, an asymmetric solvent-resistant membrane was prepared by the spin-coating method and evaporative phase transformation that selectively desorbed CO2 from methanol-rich solution. The effects of the casting liquid concentration, rotating coating speed, drying temperature, and different types of polyimides on the properties of the desorption membrane were studied. Optimal conditions were determined, with a 17 wt % casting liquid concentration, 1000 rpm rotational coating speed, 45 degrees C drying temperature, and a 4:1 ratio of PI84 to PIMM. Under these conditions, a solvent-resistant desorption membrane was achieved, exhibiting a flux of 903.4 g/(m(2)<middle dot>h) and a selectivity factor of 14.1. Compared to traditional gas stripping, the membrane desorption process proves to be cost-effective, yielding >99% pure CO2. These results demonstrate a novel and promising method for capturing CO2 effectively and economically for industrial purposes.