POSTERS
Hydrogenation of Fatty Acid Methyl Esters to Fatty Alcohols at Supercritical Conditions
E-mail: svh@harrod-research.se
Large amounts, 1 million ton/year, of fatty alcohols (FOH) and their derivatives are used in detergents. FOH are mostly produced by catalytic hydrogenation of fatty acid methyl esters (FAME), at severe conditions, i.e. 250° C and 300 bar.
FAME + H2 <-> FOH + MeOH
The reaction rate is limited by the hydrogen concentration at the catalyst surface. This concentration is related to the hydrogen solubility in the FAME, which is relatively low despite the severe conditions.
The project :
In order to increase the hydrogen concentration, we add supercritical propane to the reaction mixture. In this way a substantially homogeneous mixture of hydrogen, FAME, propane and FOH can be created. In the homogeneous mixture the transport limitation for hydrogen is eliminated and very high hydrogen concentrations at the catalyst surface can be obtained. These high hydrogen concentrations result in tremendous high reaction rates. Furthermore, the concentration of hydrogen and FAME can be tuned independently of each other and of other process conditions, like temperature or pressure. In this way we are able to control the hydrogenation selectivity and avoid over-hydrogenation.
Other advantages of working at supercritical conditions are the facilitated product separation and the improved heat balance due to the heat adsorption capacity of the supercritical solvent.
Results:
Experiments are performed in our lab-scale reactor. With a central composite design the effect of several factors upon the hydrogenation activity was studied. Among the studied variables were; temperature, catalyst, residence time, hydrogen concentration etc. Preliminary results indicate that very high reactor productivity’s can be reached, with high yields in the desired product (FOH). A pilot plant for this process is under construction..
Recent publications:
Van den Hark, S., Härröd, M. (2001) Fixed-Bed Hydrogenation at Supercritical Conditions to Form Fatty Alcohols: The Dramatic Effects Caused by Phase Transitions in the Reactor.Ind. Eng. Chem. Res. 40, 5052-5057
van den Hark, S.; Härröd, M. (2001) Hydrogenation of Oleochemicals at Supercritical Single-Phase Conditions: Influence of Hydrogen and Substrate Concentrations on the Process. Appl. Catal. A: General 210, 207-215
van den Hark, S. (2000) The Use of Supercrtical Fluids to Reduce the Number of Phases in Catalytic Hydrogenation: The Reaction of Fatty Acid Methyl Esters to Fatty Alcohols. PhD Thesis; Chalmers University of Technology: Gothenburg, Sweden
Other publications
Page maintained by svh@harrod-research.se Updated: 2001-01-24