engleski

Optimization of the n-hexane isomerization process using response surface methodology

Isomerization reactions on commercial zirconium sulfate catalyst are investigated in order to determine influence of hydrogen/feed ratio, space velocity and temperature on n-hexane conversion. Investigated range of inlet parameters includes values that are applied in the industrial practice of the isomerization process. Box–Behnken experimental design was carried out in order to optimize n-hexane isomerization process. Statistical analysis of experimental data was performed to obtain second order polynomial model and the optimum conditions were determined: hydrogen/feed ratio of 6, space velocity of 2 h−1 and temperature of 170 ◦C. At optimum conditions conversion of n-hexane was 70 wt.%. In addition, temperature dependency of product composition was investigated at optimum values of hydrogen/feed ratio and space velocity. Obtained results show that methylpentanes greatly depend on temperature, unlike dimethylbutanes, in the studied range from 130 to 170 ◦C. Isomer that was produced in highest quantities was 2-methylpentane, while 3- methylpentane forms in somewhat smaller amounts. 2, 2- and 2, 3-dimethylbutanes, which contribute the most to the octane number value, are formed in relatively small quantities, amounting to less than 10 wt.% of the total amount of isomers formed.

isomerization; n-hexane; zirconium sulfate; catalyst; optimization

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