Surface-modified carbon black derived from used car tires as alternative, reusable, and regenerable catalysts for H2 release studies from sodium borohydride methanolysis

Carbon black (CB) obtained from used car tire rubbers were treated with concentrated sulfuric and nitric acids. The oxidized CB (CB-COO-Na+) is subsequently modified with epichlorohydrin (ECH) and amines including polyethylene imine (PEI). These modified CBs such as CB-PEI are used as metal-free catalysts in methanolysis of sodium borohydride (NaBH4) to produce hydrogen. The hydrogen generation rate (HGR) of 3089 +/- 44.69 mL.min(-1).g(-1) is accomplished at room temperature with CB-PEI-hydrochloric acid (HCl) catalyst. The resulting activation energy of 34.7 kJ/mol for the temperature range of -20 degrees C to +30 degrees C compares favorably to most of alternative catalysts reported in literature while reaction catalyzing capabilities of CB-PEI-HCl particles extend to the subzero temperature range (-20 degrees C-0 degrees C). The reuse and regeneration studies conducted for the CB-PEI-HCl catalyst showed that these catalysts do provide complete conversion at every use up to five consecutive runs and retain 50 +/- 2.5% of the original hydrogen generation rate at the fifth consecutive reuse. The CBs-based catalysts are fully regenerated with HCl treatment.