Micro reactor experiments on the partial isobutane oxidation as a multiphase process.


Micro reactor experiments on the partial isobutane oxidation as a multiphase process.

Willms, T.; Kryk, H.; Hampel, U.

Tertiary butyl hydroperoxide (TBHP), as an intermediate for the production of propylene oxide according to the Oxirane process, is currently produced at industrial scale by the partial oxidation of liquid isobutane using bubble columns or bubble tray reactors. In this process, liquid isobutane reacts with oxygen at temperatures of 120 to 140 °C and pressures of 25 to 37 bar at high residence times of up to 12 hours. The conversion is limited to 35 to 50 % in order to obtain a TBHP selectivity of 50 to 60 % minimizing the formation of by-products, which are caused by the decomposition of the TBHP due to the complex reaction mechanism. Besides safety aspects, the high reaction enthalpy of the oxidation as well as heat and mass transport problems are further issues of this process. In the frame of the Helmholtz-Energy-Alliance project “Energy efficient chemical multiphase processes“, this reaction is investigated for the first time as a Taylor-Flow process in a broad range of flow rates, temperatures and pressures in a micro reactor with the aim to enhance the space-time yield of the process. The advantage of micro reactors are the high surface – volume ratio for an efficient heat transfer, the related, improved – nearly inherent – safety and the resulting possibility to investigate yet unexplored process windows for instance within the explosive region of a reaction mixture. A number of levers for the process intensification have been identified. In addition to the parameter ranges studied so far, higher pressures of up to 100 bar and uninvestigated initiator types, especially e.g hydrogen peroxide and high oxidation concentrations (50 to 100%) are applied, which have not been studied yet. Also, the influence of process parameters on the start-up time is investigated. Finally, the reaction medium characteristics of the isobutane – oxidant flow is modified by adding additives to the liquid phase or inert gases to the gas phase. For all parameters, the selecti¬vity and conversion of the reaction is studied. Therefore, the reaction course is followed by sampling and analyzing the reaction by GC/MS and GC–TCD where analytical methods have been developed to detect a maximum of by-products and intermediates. In the frame of the presentation, the results of preliminary investigations and the first multiphase flow oxidation experiments are given and discussed with respect to the reaction characteristics.

Keywords: isobutane oxidation; microreactor; t-butyl hydroperoxide; two phase process

  • Poster
    10th European Congress of Chemical Engineering, 3rd European Congress of Applied Biotechnology, 5th European Process Intensification Conference ECCE10+ECAB3+EPIC5, 27.09.-01.10.2015, Nice, France
  • Contribution to proceedings
    10th European Congress of Chemical Engineering, 3rd European Congress of Applied Biotechnology, 5th European Process Intensification Conference ECCE10+ECAB3+EPIC5, 27.09.-01.10.2015, Nice, France

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