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

Adzamic, Zoran; Adzamic, Tamara; Muzic, Marko; Sertic-Bionda, Katica

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.

MATHEMATICAL optimization; HEXANE; ISOMERIZATION; RESPONSE surfaces (Statistics); PARAMETER estimation; TEMPERATURE effect; HYDROGEN; SULFATES; CATALYSTS

Chemical Engineering Research & Design: Transactions of the Institution of Chemical Engineers Part A, 2013, Vol 91, Issue 1, p100

0263-8762

Academic Journal

10.1016/j.cherd.2012.06.012