Chemical Engineering Science, Vol.87, 160-172, 2013
A study on the bifunctional isomerization of n-decane using a superior combination of design of experiments and kinetic modeling
The efficiency of a practical and easy-to-use design of experiments (DoE) in combination with formal kinetic modeling is proved by studying the isomerization of n-decane on mesoporous, bifunctional catalysts (Pd/Al-SBA-16). A series of merely eight catalyst samples showed impressively how the statistical approach, applying both DoE and kinetics, may elucidate underlying dependencies of reaction in heterogeneous catalysis, thus facilitating both preparative issues and the optimization of any catalyst system. The applied experimental design focused on the broad variation of catalyst variables during preparation, such as the calcination temperature, chloride ion concentration of the impregnation solution, or Si/Al ratio, which directly influenced the key parameters for the isomerization reaction, viz. the noble metal dispersion and the acid site density. The influence of calcination temperature was found to be negligible, but high Pd dispersion enhanced the rate of the isomerization reaction to mono-branched products considerably, while reducing the cracking tendency at the same time. Decreasing the acid site density was found to lessen the rates of all reaction pathways significantly. In addition, a minor structural modification of the support material is believed to cause a beneficial, disproportionately strong reduction of cracking. It could be shown that the resolution of every single reaction step via kinetic modeling is a very efficient tool for the characterization of catalyst performance, as any reaction path can be scrutinized in great detail when combined with the DoE-approach. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords:Catalysis;Design of experiments;Isomerization reaction;Kinetics;Mathematical modeling;Optimization