Hydrogen atom transfer between enantiomers of rac-1-phenylethanol
Did you continue reading the paper? :) The source is important and is what was needed to answer the question!

I'm just going to quote from it.


  In DKR [dynamic kinetic resolution] a chemical catalyst is added in order to racemize the enantiomers, ensuring that all the substrate can be utilized. [...] Highly successful catalysts are often Ru(II) complexes [...] The metal complex catalyses racemization by a hydrogen transfer mechanism (Scheme 2).




So, the supposed hydrogen transfer occurs via coordination to a metal, followed by β-hydride elimination. Readdition of the metal hydride across the opposite face of the resultant ketone (acetophenone in this case) produces the other enantiomer.