Efficient dehydration of bio-based 2,3-butanediol to butanone over boric acid modified HZSM-5 zeolites

The dehydration of bio-based 2,3-butanediol provides an alternative green way to produce butanone, which is mainly produced through the dehydrogenation of butanol in industry. In this research, the effect of the framework Si/Al ratio on 2,3-butanediol dehydration over HZSM-5 zeolites (Si/Al = 38-360) was investigated. HZSM-5(360) was further modified with boric acid, and the influence of the loading amount of boric acid on the dehydration performance was studied. The results showed that high Si/Al ratio was beneficial to low-temperature activation of 2,3-butanediol and the methyl migration to 2-methyl propanal. 1.0%B/HZSM-5(360) not only showed best performance at 180°C but also kept stable activities between 180-300°C with a high LHSV 2.4 h^-1. According to the characterization results, excellent performance over HZSM-5(360) was due to the highest amount of strong acidic sites (1.1674 mmol g^-1) attributed to H-bonded hydroxyl groups, normally silanols. Coexistence of more effective extraframework B-OH species and retained silanols were responsible for the promotion of catalytic performance over 1.0%B/HZSM-5(360).