Thermal-enzymatic Hydrolysis of lignocellulosic Biomass for the
Production of Platform Chemicals

Wienke Hüppop

With  growing  shortage  of global  oil  resources  and  increasingly  strict  environmental  regulations,  industry and  research  become  more  interested  in  sustainable  sources  of  raw  materials.  In  this  context,  not  only fossil  fuel  substitutes  but  in  particular  alternatives  for  oil-based  polymers  and  chemicals  have  to  be developed.  For  some  years  now,  products  from  starch based  biomass  have  been  used,  e.g.  biodiesel  or
bioethanol.  However,  these  products  are  in  strong  competition  with  food  and  animal  feed  industry. 2nd generation  Biorefineries  are  an  advancement  of  this  concept.  Here,  lignocellulosic  residues  from agriculture  and  forestry  are  processed.  The  three  major  constituents  of  the  lignocelluloses  (cellulose, hemicellulose and lignin) are split into sugar monomers and lignin – so-called platform chemicals which are
now available for further processing steps.

Type and composition of the applied biomass strongly varies by season and by cultivation. For commercial
application of the biorefinery concept, the development of a robust and flexible process is essential. At the Institute  of  Thermal  Separation  Processes,  wheat  straw  is  splitted  thermally  and  enzymatically  into  its constituents  in  a  single  high-pressure  fixed-bed  reactor.  The  major  benefits  of  this  process  are  the avoidance of aggressive solvents and chemical additives as well as the low plant complexity. 

In current second generation biorefineries, bioethanol from glucose usually is the target product. Most of the  existing  biorefinery  plants  only  thermally  recycle  the  hemicelluloses  and  lignin  fractions  in  order  to cover  their  energy  demand  for  ethanol  production.  However,  the  processing  of  lignocellulosic  feedstock also  allows  the  production  of  high-value  co-products  from  hemicellulose  and  lignin — the  key  to  a  costeffective  and  competitive  process.  In  the  context  of  the  BMBF-project  „Bioraffinerie  2021“  this  research project  deals  with  the  characterization  of  the  fixed-bed  process,  focusing  particularly  on  lignin.  Previous works  demonstrated  the  operability  of  the  process  at  lab  scale  and  small  demonstration  scale.  Further experimental studies as well as process modeling and simulation need to be executed in order characterize the mechanisms inside the reactor in more detail and to investigate scale-up possibilities.