Effect of various Co–B catalyst synthesis conditions on catalyst surface morphology and NaBH4 hydrolysis reaction kinetic parameters

• Published in: International journal of hydrogen energy 2014-01, Vol.39 (4), p.1648-1663
• Main Authors: Chen, Yih-Hang, Pan, Chuan-Yi
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Catalysts; Chemical reduction method; Co–B catalyst; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrolysis; Hydrolysis reaction; Kinetic parameters; Mathematical models; Morphology; NaBH4; Polymers; Reduction; Resins; Synthesis
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.11.067

The objective of this work is to study the effect of various Co–B catalyst synthesis conditions on the catalyst surface morphology and kinetic parameters. The Co–B catalyst was synthesized on IR-120/TP-207 resin surface by using ion exchange and chemical reduction method using NaBH4 as a reduction agent. The reduction conditions which were investigated here were: reduction temperature, NaBH4 concentration, pH value, NaBH4 adding flowrate and different types of resins. The result shows reduction temperature gives the most dramatic effect on surface morphology which is caused by competing reactions of reduction and hydrolysis. Low reduction temperature resulted in a slower Co–B reduction rate and made the catalyst surface denser with a branched structure. This created more surface area than higher reduction temperatures. Low reduction temperature catalyst had the better performance on NaBH4 hydrolysis reaction for hydrogen generation rate. The optimal reduction temperature of the Co–B/IR-120 is 25 °C. The L-H model was used to regress kinetic parameters from the experiment data. The frequency factor, activation energy and adsorption constant are 1.17 × 109 mol gcat−1 min−1, 70.65 kJ mol−1, and 6.8 L mol−1 at 40 °C, respectively. Finally, the TP-207 resin was used instead of IR-120. After scanning for all catalyst synthesis conditions, the Co–B/TP-207 had the higher catalyst loading, faster hydrogen generation rate and more stable than Co–B/IR-120. •Ion exchange and chemical reduction method can easily synthesize Co–B catalysts.•Reduction temperature had the most dramatic effect on catalyst surface morphology.•Co–B/TP had: higher catalyst loading, faster hydrogen generation rate than Co–B/IR.•Co–B/TP demonstrated more stable than Co–B/IR.