Microreactor for biodiesel production

Aim of this project is the development of a new process using supercritical methanol (T > 240 °C, P > 80bar) for the production of biodiesel based on waste cooking oil.

Project abstract

The advantages are the use of low-cost raw materials with a high amount of free fatty acids (FFA), the combination of transesterification and esterification in one step and the reduction of byproducts. However, the generation of methanol under supercritical conditions requires a high amount of energy. This shall be compensated by different techniques, e. g. use of waste energy recovery and micro process engineering.

This research is done in cooperation with Biowerk Sohland GmbH and funded by German Federal Environmental Foundation.

The experiments were carried out with different raw materials, e. g. normal waste cooking oils, rapeseed fatty acids with FFA contents up to 65 % and mixing products as side streams of the classical biodiesel production. Two different electrically powered microreactors were developed, which can be used at high temperature and high pressure. One of them allows in-situ monitoring of the reaction in the microchannel by optical methods.

Oil and methanol are pumped by HPLC pumps to get 100 bars, mixed and fed into the microreactor. The following picture shows one microreactor with 6 sapphire windows. It consists of two stainless steel plates, where the lower one contains a milled meander-shaped microchannel. It has a width of 1.2 mm, a depth of 1.5 mm and a length of 2000 mm. Both plates are connected by diffusion bonding at high temperature. With this microreactor  transesterification and esterification of different raw materials were carried out. The conversion was determined by gas chromatography, first.

Additionally, the phase behavior within the microreactor can be observed visually by using a flash lamp and a CCD camera. In order to determine the concentrations of educts and products, the radiation of a pulsed Nd:YAG laser is focused into the microchannel and the resulting Raman stray light can be measured.

A preliminary assessment of the process economics was done for an autarkic process and an integrated process, where mixed products from the conventional process or additional raw materials with a high amount of free fatty acids can be used. The current status is that the integrated process might allow an economical production of biodiesel based on waste cooking oil with high FFA amount.


Publications / Conferences :

New process to produce biodiesel of waste cooking oil with supercritical methanol in a microreactor,

G. Rinke, J. Kiehl, F. Rinkewitz, R. Dittmeyer, C. Protze, H. Holpe. 2nd Green & Sustainable Chemistry Conference, 14. – 17. Mai 2017, Berlin


Influence of hydrodynamics on reaction progress of CO2 absorption in caustic soda in Taylor flow regime in microchannels by means of spatially and temporally resolved in-situ laser Raman spectroscopy,

D. Schurr, D. Rieder, G. Rinke, R. Dittmeyer, 10th World Congress of Chemical Engineering, Barcelona, Spain, 1st - 5th October, 2017


Spektroskopische in-situ-Messtechniken und Anwendungen in der Mikroverfahrenstechnik

G. Rinke, D. Schurr, R. Dittmeyer.,Colloquium of Optical Spectrometry (COSP) 2017,Berlin, 27th to 29th November 2017


Characterization of a Raman spectroscopy and holographic system for gas-liquid flows in microchannels

D. Schurr, J. Guhathakurta, S. Simon, G. Rinke, R. Dittmeyer, Chemical Engineering & Technology 2017, 40(8), 1400–1407


Simultaneous in situ characterisation of bubble dynamics and a spatially resolved concentration profile: a combined Mach–Zehnder holography and confocal Raman-spectroscopy sensor system,

J. Guhathakurta, D. Schurr, G. Rinke, R. Dittmeyer, S. Simon,  J. Sens. Sens. Syst. 2017, 6, 223-236


Laser-spektroskopische Methoden zur Konzentrationsbestimmung unter Prozessbedingungen

G. Rinke, D. Schurr, R. Dittmeyer., Jahrestreffen Reaktionstechnik, Würzburg, 2.-4. Mai 2016


Application of spatially resolved in-situ laser Raman spectroscopy to measure the concentration in the liquid slugs of Taylor flows

D. Schurr, G. Rinke,R. Dittmeyer.,14th International Conference on MicroReaction Technology, Sept. 12-14, 2016, Beijing, China

Local concentration measurements in the wake of bubbles based on in-situ Raman spectroscopy and statistical analysis

D. Schurr, J. Guhathakurta, Y. Baroud, S. Simon, G. Rinke, R. Dittmeyer., 9th International Conference on Multiphase Flow, May 22nd –27th 2016, Firenze, Italy


Mikroreaktor Biodiesel aus Altspeisefetten mit überkritischem Methanol

Franz-Georg ElpersDeutsche Bundesstiftung Umwelt (DBU), Pressestelle, 15.05.2015, idw-online.de/de/news631084


Biodiesel aus Altspeiseöl. Kommt Biodiesel bald aus dem Mikroreaktor?

M.A. Manja Wühr (Redakteur), Process Chemie Pharma Verfahrenstechnik (online Magazin), 19.05.15, www.process.vogel.de/kommt-biodiesel-bald-aus-dem-mikroreaktor-a-489697/


In-situ Messung von Konzentrationen in Mikroreaktoren unter Prozessbedingungen mit Laser-Raman-Spektroskopie

G. Rinke, D. Schurr, R. Dittmeyer, Karlsruher Institut für Technologie, Institut für Mikroverfahrenstechnik, Jahrestreffen der ProcessNet-Fachgruppe Mikroverfahrenstechnik, DECHEMA, 14.9.2015, Frankfurt, www.dechema.de/mikro2015.html