Modeling and Optimization Of High Selective Dehydrogenation Catalyst For Higher Paraffins

Abstract

Catalytic paraffin dehydrogenation for the production of olefins has been in commercial use since the late 1930s. However, there are some interesting recent developments worthy of further research and development. During World War II, catalytic dehydrogenation of butanes over a chromia-alumina catalyst was practiced for the production of butenes that were then dimerized to octenes and hydrogenated to octanes to yield high-octane aviation fuel. Dehydrogenation employs chromia-alumina catalysts and, more recently, platinum or modified platinum catalysts. Important aspects in dehydrogenation entail approaching equilibrium or near-equilibrium conversions while minimizing side reactions and coke formation. Commercial processes for the catalytic dehydrogenation of propane and butanes attain per-pass conversions in the range of 30–60%, while the catalytic dehydrogenation of C10–C14 paraffins typically operates at conversion levels of 10–20%. In the year 2000, nearly 7 million metric tons of C3–C4 olefins and 2 million metric tons of C10–C14 range olefins were produced via catalytic dehydrogenation. Experimental investigation was carried out to study the effect of process variables on conversion and selectivity of olefins, aromatics, light ends from selective dehydrogenation of higher paraffins of C10-C13 mixture with Pt-Sn-Al2O3 catalyst, using Box-Behnken experimental design. Four factor, three level Box-Behnken response surface experimental design requires twenty seven runs including three centre point experiments. Statistical analysis of the experimental data and response values was carried out to identify main factor and interaction effects. Pure error was determined from the three repeated experiments at the central points of the four factors. Full quadratic models were fitted for conversion and selectivity of olefins, aromatics and light ends. Best operating conditions are obtained from response optimizer and contour plots.