Conversion of KCl into KBH₄ by Mechano-Chemical Reaction and its Catalytic Decomposition

Abstract

Production of KBH₄, in the presence of KCl, B₂O₃ and MgH₂ by means of a mechanical reaction and a dehydrogenation kinetic, constitute the main parts of this study. Operating time and reactant ratio are considered as two parameters for the mechanical reaction to obtain the maximum yield. The production process was carried out in a ball milling reactor, and the product residue was purified with ethylene diamine (EDA) and subsequently characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and x-ray Diffraction (XRD) analyses. Optimum time for mechano-chemical treatment and reactant ratio (MgH₂/KCl) were obtained as 1000 min and 1.0, respectively. Synthesized and commercial KBH₄ were compared by hydrolysis tests in the presence of Co_1−xNi_x/Al₂O₃ heterogeneous catalyst. Hydrogen generation rates, activation energy and order of the KBH₄ decomposition reaction were obtained as 1578 ${\hbox{mL}}_{{{\rm{H}}_{2} }} \;\min^{ - 1} \;{\hbox{g}}_{\rm{catalyst}}^{ - 1}$, 39.2 kJ mol⁻¹ and zero order, respectively.