Qinglin Huang

CHAPTER 12 – Simulation of Hydrogen Purification by Pressure-Swing Adsorption for Application in Fuel Cells

Publisher Summary Hydrogen is a clean and sustainable energy resource that only emits water and heat resulting from the combustion. One of the important hydrogen applications is its use in proton-exchange membrane fuel cells (PEMFC), which have been considered an attractive technology for transportation, commercial building, home, and small-scale power generation. This chapter explains that single-component adsorption isotherms of CO2, CO, CH4, and H2 in activated carbon and zeolite 5A were experimentally measured and described by the Langmuir model. The two adsorbents exhibited various affinities and adsorption capacities for the selected probe species. Therefore, their respective effects on impurity removal from the PSA process had to be explained and clarified. A theoretical two-layered-bed PSA model has been developed for studying impurity removal from SMR off-gas for producing fuel-cell-grade hydrogen, where CO2, CO, and CH4 concentrations are required to be less than 100, 10, and 100 ppm, respectively. The optimization routines were also carried out to examine the optimal conditions for the separation of mixture using the single-bed PSA process with layered adsorbents operated in the Skarstrom cycle. Using the dynamic optimizer in gPROMS, the optimal operation conditions for the PSA process based on different objective functions could also be obtained. gPROMS proved to be an effective tool for PSA simulation and simple optimization. The chapter explains the simulation of hydrogen purification by pressure-swing adsorption for application in fuel cells.

Adsorption and diffusion characterization of mesoporous Al-MCM-48 as a potential catalyst support

The mesoporous alumina MCM-48 materials were investigated as potential catalyst supports in the present work. The adsorption and diffusion properties of 1-methylnaphthalene in a series of Al-MCM-48 samples, with different Al contents, were compared to reference MCM-48 and H-USY samples using a standard gravimetric technique and zero length column (ZLC) method, respectively. Compared to the reference MCM-48 sample, Al-MCM-48 samples exhibited higher adsorption capacities and stronger adsorption affinities for 1-methylnaphthalene as a probe molecule. Furthermore, Al-MCM-48 samples revealed faster diffusion of the probe molecule than the conventional H-USY zeolite support, demonstrating its advantage as a promising catalyst support. The increasing content of aluminium in MCM-48 materials generates more acid sites on the surface, resulting in larger adsorption capacity and slower diffusion rate of the sorbate. The results suggested the important effect of aluminium content within Al-MCM-48 on overall adsorption and diffusion properties of aromatic compounds in light cycle oil. Therefore, it is critical to keep an optimum balance between pore volume and acidity of Al-MCM-48 by altering Si/Al ratio in order to ensure the improved diffusion and adsorption of large molecules.