Process intensification of the chlor-alkali electrolysis by using
a rotor-stator spinning disc membrane electrolyzer
Citation for published version (APA):
Granados Mendoza, P., Moshtari Khah, S., de Groot, M. T., Keurentjes, J. T. F., Schouten, J. C., & van der Schaaf, J. (2016). Process intensification of the chlor-alkali electrolysis by using a rotor-stator spinning disc membrane electrolyzer. In 67th ISE meeting, 21/08/16 → 26/08/16, The Hague, The Netherlands (pp. 1)
Document status and date: Published: 01/01/2016 Document Version:
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Process intensification of the chlor-alkali electrolysis by using a
rotor-stator spinning disc membrane electrolyzer
P. Granados Mendoza1, S. Moshtarikhah1, M.T. de Groot2, J.T.F. Keurentjes1, J.C. Schouten1
and J. van der Schaaf1,*
1 Laboratory of Chemical Reactor Engineering, Department of Chemical Engineering and Chemistry,
Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven
2 AkzoNobel Industrial Chemicals B.V., P.O. Box 75730, 1070 AS Amsterdam
* Corresponding author: J.vanderSchaaf@tue.nl
One of the major industrial electrochemical processes is the chlor-alkali process, which produces roughly 60 million tonnes of chlorine per year, in addition to sodium hydroxide and hydrogen. These products are important chemicals and building blocks for many organic and inorganic substances and approximately 55% of all the specialty chemical products require one of the chlor-alkali products as a precursor [1]. In general chlorine is transported from the chlor-alkali plant to the customer by pipeline. However, small scale chlorine consumers that are not located in chlorine clusters typically still rely on chlorine supply by rail. In these cases, small scale chlorine production units at the customer’s location could offer an alternative for the less desired rail transport. Modular plants of the size of standard shipping containers that offer flexible and on-demand production are ideal for this purpose. Furthermore these skid-mounted modular plants require minimum installation at the user’s location, where they simply need to be connected to the utilities and pipelines. This type of “plug and produce” modular plants require intensified technologies in order to achieve high productivity in small equipment volumes. Typical industrial current densities are nowadays in the range of 5-7 kA/m2 [2]. In order to achieve the
intensification of the chlor-alkali process it is necessary to design an electrochemical reactor that allows operating at higher current densities while dealing with the associated challenges: 1) increased bubble generation causing larger ohmic drops and increased power consumption, 2) more pronounced concentration gradients in the boundary layers leading to undesired side-reactions and current efficiency losses, and 3) increased membrane voltage drop and the possibility of lowered membrane permselectivity. The spinning disc reactor (SDR) is a type of rotating equipment that is suitable for this purpose [3]-[4]. The rotor-stator spinning disc reactor (RS-SDR) configuration which is investigated in this work consists of a rotating disc in a cylindrical housing, with a typical gap distance between the rotor and the stator in the order of 1-5 mm. The high velocity gradient between the rotor and the stator and the high shear forces cause high turbulence that intensify the liquid-solid mass transfer [4] and decrease the concentration gradients. Furthermore, the high shear and high centrifugal forces of the rotor-stator spinning disc reactor promote the efficient disengagement of gas bubbles even at high gas production. The small reactor volume contributes to a safer processing of hazardous materials and offers fast start-up and shut down which is beneficial when on-demand production is required. In this work we present a zero gap spinning disc membrane electrochemical reactor (SDMER) designed for the intensification of the chlor-alkali process [6],[7]. For the range of current densities investigated, lower cell voltages were achieved in the SDMER compared to the parallel plate cell. The increase in potential with increasing current density was approx. 0.14 V per kA/m2 for the SDMER. This value was approx. 3 times higher for the parallel plate
cell. Additionally, the SDMER allowed stable operation at high current densities (20 kA/m2). Results
obtained here indicate that the spinning disc reactor is a suitable technology for the intensification of the chlor-alkali process, although significant further developments are still required.
[1] G.G. Botte, Electrochemical Manufacturing in the Chemical Industry, Electrochem. Soc. Interface. (2014) 49–55.
[2] T.F. O’Brien, T. V. Bommaraju, F. Hine, Handbook of Chlor-Alkali Technology, Springer US, Boston, MA, 2005.
[3] J. van der Schaaf, et al., High-gravity and high-shear gas–liquid contactors for the chemical process industry, Curr. Opin. Chem. Eng. 1 (2011) 84–88.
[4] M. Meeuwse, Rotor-stator spinning disc reactor, PhD thesis, Eindhoven University of Technology, 2011.
[5] P. Granados Mendoza et al., Liquid solid mass transfer to a rotating mesh electrode, article in preparation.
[6] P. Granados Mendoza et al., Intensification of the chlor-alkali process by using a spinning disc membrane electrolyzer, article in preparation.
