In the last decade, zeolitic imidazolate frameworks (ZIFs) have been studied extensively for their potential as selective separation membranes. In this review, we highlight unique structural properties of ZIFs that allow them to achieve certain important separations, like that of propylene from propane, and summarize the state of the art in ZIF thin-film deposition on porous substrates and their modification by postsynthesis treatments. We also review the reported membrane performance for representative membrane synthesis approaches and attempt to rank the synthesis methods with respect to potential for scalability. To compare the dependence of membrane performance on membrane synthesis methods and operating conditions, we map out fluxes and separation factors of selected ZIF-8 membranes for propylene/propane separation. Finally, we provide future directions considering the importance of further improvements in scalability, cost effectiveness, and stable performance under industrially relevant conditions.

Despite their potential for the scalable production of mixed-matrix membranes (MMMs), the MMMs prepared by the polymer-modification-enabled in situ metal–organic framework formation (PMMOF) process showed a considerable reduction in gas permeability as the filler loading increased. It was hypothesized that a correlation existed between the decrease in permeability and the change in the properties of the polymer, such as free volume and chain flexibility, upon in situ MOF formation. Herein, we aim to address the permeability reduction by using a cross-linked polyimide (6FDA-DAM:DABA (3:2)). It was found the degree of cross-linking affected not only the properties of the polymer, but also the in situ formation of the ZIF-8 filler particles in the cross-linked polymer. The proper degree of cross-linking resulted in suppressing C₃H₆ permeability reduction, suggesting a possible strategy to overcome the issue of PMMOF. The swelling of the polymer followed by chain rearrangement during the PMMOF, as well as the structural rigidity of the polymer, were found to be critical in mitigating permeability reduction.

A multiband linear CMOS power amplifier (PA) is developed to cover multiple LTE bands from 800 to 2000 MHz using a single PA core. The single-chain PA is based on a two-stage design using stacked-FET cells, and is designed to support any combinations of low/high dual bands out of five popular 3G/4G bands (Band 1/2/4/5/8). To avoid the performance degradation by covering such a wide bandwidth using a single PA-core, the frequency reconfigurability has been applied to the stacked-FET cells, interstage matching as well as the output matching. To further enhance the linearity and efficiency, a phase-based linearizer is employed and reconfigured according to the operating frequencies. W-CDMA test on the fabricated PA shows adjacent channel leakage ratios (ACLRs) better than -39 dBc up to the rated linear power of 28.5 dBm and power-added efficiencies (PAEs) higher than 40.7% and 46% for high- and low- frequency band groups, respectively. Compared with the dedicated PAs using the same process, PAE degradation is limited to 1.6 ~ 3.3%. To our knowledge, this work is among the best results from the single-chain PAs for 3G/4G mobile applications.

Direct air capture (DAC) is a key negative-emission technology, although processing large volumes of ambient air and regenerating adsorbents remain energy- and cost-intensive. An open-air Brayton cycle (OABC)-coupled DAC system integrates air handling, regeneration heat supply, and electricity generation, making adsorbent compatibility with its operating conditions essential. Herein, a system-driven framework combining process-based screening, experimental comparison, and experiment-informed system assessment was developed. Amine- and carbonate-based supported adsorbents were selected based on OABC-derived regeneration conditions, system efficiency, adsorption performance, and cost. The selected adsorbents were systematically compared for CO2 uptake under dry and humid conditions, gravimetric and volumetric capacities, thermal stability and cyclic performance. PEI@FS exhibited higher gravimetric uptake, whereas K2CO3@γ-Al2O3 provided higher humid volumetric capacity and greater thermal stability at the OABC-derived regeneration temperature of 250 oC. At the reference electricity selling price of $65 MWh-1, incorporating the measured properties of K2CO3@γ-Al2O3 into the OABC-DAC model yielded an optimal bed volume of 10,300 m3 and an estimated minimum LCOD of $190.04 tCO2-1. This LCOD was below both the $200 tCO2-1 long-term target and the previous OABC-DAC estimate of $307 tCO2-1. Beyond CO2 uptake, adsorbent price and stability were key practical considerations for material selection in the OABC-DAC system.