The gas permeability performance of thermally rearranged polypyrrolone (PPL-450) membranes have been experimentally evaluated under similar industrial conditions of gas mixtures, pressures, and stage-cuts. The membranes were synthesized from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 3.3′-diaminobenzidine (DAB). The thermal treatment of the PPL-450 was accomplished under vacuum at 450 °C. Several gas mixtures (binary, ternary and quaternary) were utilized to study the performance of the PPL-450 membranes for CO₂ removal and helium recovery from natural gas streams. The quaternary feed gas-mixture was composed of 59% CH₄, 30% N₂, 10% CO₂ and 1% C₂H₆, which represent a low quality natural gas. Three pressures (400, 600, and 800 psig) and five stage-cuts (1.2, 2.8, 4.2, 6.4, and 9.8%) were considered for the study. It was observed that the permeability values of all gases were decreased for mixed-gas experiments when compared to that of the single-gas permeability. On the other hand, CO₂/CH₄ permeability ratio was increased from 29, for pure gas, to 45 for quaternary gas-mixture. Likewise, the He/CH₄ permeability ratio was increased from 33, for pure gas, to 46 for ternary gas-mixture. Furthermore, at 800 psig and 9.8% stage-cut, PPL-450 was able to remove 80% of CO₂ from the quaternary gas-mixture. In another study of a very dilute helium-concentration (0.14%) more than 80% helium was recovered at 800 psig and 5% stage-cut. Moreover, in all gas mixtures containing CO₂, the PPL-450 membrane demonstrated an outstanding resistivity to CO₂-induced plasticization at high pressures.

热重排聚吡咯烷酮（PPL-450）膜的气体渗透性能已在相似的混合气体，压力和分段切割工业条件下进行了实验评估。该膜由4,4'-（六氟异亚丙基）二邻苯二甲酸酐（6FDA）和3.3'-二氨基联苯胺（DAB）合成。PPL-450的热处理是在450°C的真空下完成的。几种混合气体（二元，三元和四元气体）用于研究PPL-450膜从天然气流中去除CO ₂和回收氦气的性能。季进料气体混合物的组成为59％CH的₄，30％N ₂，10％CO ₂和1％C ₂ H ^ ₆，代表劣质天然气。研究中考虑了三个压力（400、600和800 psig）和五个切入点（1.2、2.8、4.2、6.4和9.8％）。观察到，与单气体渗透率相比，混合气体实验中所有气体的渗透率值均降低。另一方面，CO ₂ / CH _4的渗透率从纯气体的29提高到四元气体混合物的45。同样，He / CH _4的渗透率从纯气体的33增加到三元气体混合物的46。此外，在800 psig和9.8％的分级压力下，PPL-450能够去除80％的CO ₂来自四元混合气体。在另一项非常稀氦浓度（0.14％）的研究中，在800 psig和5％分级切割时回收了80％以上的氦。此外，在所有包含CO _2的气体混合物中，PPL-450膜在高压下均表现出出色的抵抗CO ₂诱导的塑化的能力。