Dehydrogenation of neohexane to neohexene on platinum polymetallic catalysts

Selective dehydrogenation of neohexane to neohexene was carried out on platinum polymetallic catalysts at high dilution in steam to overcome severe chemical equilibrium limitations. The conversion at 550°C, WHSV = 1 h^-1, and a dilution ratio of 20 was close to equilibrium values of 17%. Two catalysts, Pt-Sn-K/alumina and Pt-Sn-K-Fe/alumina, yielded similar initial performances of high selectivity of 83 mol %, significantly higher than those of supported Cr catalysts. However, fast coke formation is inherent to this process. Therefore, regeneration of the catalysts is a critical step in the process. Steam regeneration is the most practical method of regeneration if the catalyst performances can be retained for many cycles. Addition of Fe to the Pt-Sn-K/alumina catalyst yielded excellent long-term stability in steam regeneration compared with the poor behavior of the basic Pt catalyst.