Conference Program

View abstract Hide abstract

Abstract: TEST1, TEST2TEST1, TEST2, TEST1, TEST2TEST1, TEST2

View abstract Hide abstract

Abstract: H2 has garnered increased attention as a highly efficient and clean energy vector that can be produced via CH4 decomposition without causing COx emissions. To purify H2 for fuel cell applications (>99.97%) and to generate pure CH4 (>90%, with trace levels of C2 hydrocarbons) for natural gas grids, a subsequent separation technology, namely dual-pressure swing adsorption (dual-PSA), is required. Since the 1990s, metal-organic frameworks (MOFs) have been extensively studied for various applications. Notably, the MOF MIL-100(Fe) offers high CH4 adsorption capacity and stability. This work aims to design a two-stage PSA process, packed with MIL-100(Fe) and featuring a recycling stream, to separate H2 from CH4, along with minor C2H6 amounts, from the exhaust gas of a typical CH4 decomposition non-thermal plasma reactor, at 303 K and 1 bar, containing either a low or high H2 content (i.e., 27.8%/63.4%/8.8% H2/CH4/C2H6 or 57.1%/31.1%/11.7% H2/CH4/C2H6). Single-component adsorption equilibrium isotherms were measured at 303, 313, and 333 K, over a pressure range of 0-5 bar, using a magnetic suspension microbalance. Breakthrough curves were performed at 1 bar and 308 K on a lab-scale fixed-bed unit with a 0.775 m bed length. The Langmuir equation accurately describes pure-component adsorption, and the extended Langmuir equation is used to represent multicomponent adsorption equilibria. A mathematical model was developed to predict the breakthrough curves through the gPROMS ModelBuilder. The experimental breakthrough results were in good agreement with the predictions, validating the model, which was then used to design, simulate, and optimize a dual-PSA system with recycle using a fresh feed with either a low or high H2 content. A seven-step cycle was considered for each PSA unit for both studied fresh feed compositions. The corresponding cycle extensions for a four-column unit, applied to PSA 1 and PSA 2, for both studied fresh feed compositions, are shown in Fig. 1 of the abstract, alongside the ratios between each cycle step time and the feed time. The optimal result obtained for the low H2 content case was 99.991% H2 purity, with an 87.2% H2 recovery rate. In comparison, the optimal result obtained for the high H2 content case yielded a 99.991% H2 purity with a 96.8% H2 recovery and an energy consumption of 46.8 (vs. 105.9) W h molH2-1.