Sodium metaborate (NaBO2) is the hydrolysate of sodium borohydride (NaBH4) for hydrogen production. Trimethyl borate (B(OCH3)3), the major reactant for producing sodium borohydride via the Brown-Schlesinger process, is successfully regenerated from sodium metaborate (NaBO2) via a sequential process including reacting with sulfuric acid, cooling crystallization, and reactive esterification distillation. The metaborate is first converted to boric acid (H 3BO3) by reacting with sulfuric acid, bypassing formation of borax (Na2B4O7•10H2O) required in a conventional process. Cooling crystallization is utilized to separate and purify boric acid from coexisting sodium sulfate (Na 2SO4). Subsequently, trimethyl borate is formed via esterification of boric acid with methanol, in which reactive esterification distillation is adopted to facilitate the esterification and purify the product. Formation of boric acid and trimethyl borate is confirmed with X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and gas chromatography (GC). Approximately 55% of sodium metaborate could be converted to boric acid, along with a production yield from 74.1% to 96.5% realized for trimethyl borate esterified from the as-produced boric acid.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering