Katholieke Universiteit Leuven

Ifast Nv

Bart Steenackers

Dirk De Vos

Pascal Mertens

Luc De Cooman

The invention relates to a process for the production of hexahydro-iso-alpha-acids starting from iso-alpha-acids (or tetrahydro-iso-alpha-acids) in which iso-alpha-acids (or tetrahydro-iso-alpha-acids) are mixed with a heterogeneous ruthenium containing catalyst, that catalyzes the hydrogenation from iso-alpha-acids or tetrahydro-iso-alpha-acids to hexahydro-iso-alpha-acids, either in solvent-free conditions, or in the presence of a solvent phase (e.g. carbon dioxide, water, ethanol or another organic solvent, or mixtures thereof), and in the absence or presence of other hop compounds (such as beta-acids). The resulting mixture is then subjected to a temperature at which the iso-alpha-acid (or tetrahydro-iso-alpha-acid) containing reaction medium is sufficiently low in viscosity to allow easy mixing with the heterogeneous ruthenium containing catalyst and held under a hydrogen containing atmosphere (either pure hydrogen gas or mixed with an inert gas) for a reaction time sufficient to effect high conversion of the iso-alpha-acid (or tetrahydro-iso-alpha-acid) reactant into the hexahydro-iso-alpha-acid product.

Method for hydrogenation of iso-alpha-acids and tetrahydro-iso-alpha-acids to hexahydro-iso-alpha-acids

The invention relates to a process for the production of iso-alpha-acids starting from hop alpha-acids in which an hop alpha-acid containing feed is contacted with a heterogeneous alkaline earth metal based catalyst, that essentially does not dissolve in the alpha-acid containing feed or in the iso-alpha-acid product phase, either in solvent-free conditions or in the presence of water, carbon dioxide, or an organic solvent or a mixture thereof. The resulting mixture is subjected to a temperature of at least 293 K, preferably under an inert atmosphere, for a time sufficient to effect high conversion of the alpha-acid reactant into the iso-alpha-acid product. The molar ratio of alpha-acid to earth alkaline metal (Mg, Ca, Sr, Ba) varies preferably between 0.2 and 20. After the isomerization process, the heterogeneous alkaline earth metal based catalyst can be quantitatively separated from the iso-alpha-acid product phase by liquid-solid separation techniques.

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Kasterlee, Belgium

Bart Steenackers