Kinetics of hydrogen adsorption on MgH2/CNT composite

• Hydrogen adsorption comparisons of commercial, milled, and MgH2 composite.
• Hydrogen adsorption capacity and kinetics improves tremendously by CNT embedding.
• Unsteady state modeling and simulation of adsorption kinetics.

Magnesium hydride (MgH2)–carbon nanotubes (CNT) composite has been prepared by high-energy ball milling method and their experimental and kinetic hydrogen adsorption studies was assessed. Hydrogen adsorption studies were performed by Sievert’s volumetric apparatus and kinetic evaluation was conducted by surface chemistry and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type mode. Powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were performed. Hydrogen adsorption capacity of commercial MgH2, milled MgH2, and MgH2/CNT composite are found to be 0.04, 0.057, and 0.059 g (H2)/g (MgH2) at 673 K and hydrogen pressure of 4.6 MPa. Addition of 5 wt% of CNTs to MgH2 proved to be very critical to enhance hydrogen adsorption as well as to improve its kinetics. It was observed that hydrogen adsorption is not in quasi-state equilibrium and is modeled using kinetic rate laws.

Figure optionsDownload as PowerPoint slideCommercial, milled, and MgH2 composite samples for hydrogen uptake studies.