Inhibition of Metal Hydrogenation Catalysts by Biogenic Impurities

Abstract

We show that supported Ni, Pt, and Pd catalysts used for liquid phase hydrogenation are inhibited by the biogenic impurities present in biologically-derived feedstocks used to produce high-value chemicals. The effects of thiamine HCl, cysteine, methionine, biotin, tryptophan, niacin, threonine, and p-aminobenzoic acid were elucidated by collecting adsorption isotherms of these species and by quantifying their influence on the rate of cyclohexene hydrogenation at 323 K. Inhibition increases in the order of Pd \ Pt \ Ni and generally correlates with the binding energies of sulfur and nitrogen. The equilibrium constants reported here for adsorption of these species on Ni, Pt, and Pd can facilitate the design of separation systems and new catalysts used for upgrading biologically-produced platform molecules.

Integrated Bio- and Chemocatalytic Processing for Biorenewable Chemicals and Fuels

“…While alanine has shown a competitive and irreversible inhibition of the lactic acid hydrogenation, theronine has shown a negligible effect on the three catalysts for cyclohexene hydrogenation [49]. While alanine has shown a competitive and irreversible inhibition of the lactic acid hydrogenation, theronine has shown a negligible effect on the three catalysts for cyclohexene hydrogenation [49].…”

“…Model biogenic impurities such as amino acids, proteins and vitamins and their mechanism of deactivation of the metal catalyst (Ru, Ni, Pt, Pd) for a hydrogenation reaction are listed in Table 2. However, thiamine is predicted to dissociate on the metal surface leading to the formation of atomic sulphur, while cysteine remains intact on the metal surface [49]. In contrast, amino acids having no sulphur lead to partial and reversible reduction in catalyst activity [49].…”

“…While alanine has shown a competitive and irreversible inhibition of the lactic acid hydrogenation, theronine has shown a negligible effect on the three catalysts for cyclohexene hydrogenation [49]. Further decomposition to elemental sulphur is not expected [49]. In addition, the amino acid units (e.g.…”

“…p-Aminobenzoic acid p-Aminobenzoic acid may bind through amine or carboxylic acid moiety to the catalyst surface [49].…”

“…The deactivation studies on heterogeneous catalysts by biogenic impurities have been limited in their scope as the studies are conducted only for the hydrogenation reactions on metal catalysts [49,54]. Catalytic transformation of platform molecules in integrated processing will require a comprehensive understanding of a pool of reactions that can be applied for making a desired product on an oxide, metallic, bimetallic or a solid acid catalyst, where we expect similar interactions of biogenic impurities on the catalyst surface.…”