Liquid phase processing

Liquid Phase Processing (LPP) or Liquid Phase Reforming (LPR) is the treatment of organic material in the liquid phase. In case water is used as the solvent, LPR is equivalent to Aqueous Phase Reforming (APR). Schematically the process is shown in the diagram below.

Liquid phase processing BTG


Typically, the process takes place at elevated pressure to keep the solvent in the liquid phase. Compared to gas phase operation higher energetic efficiencies are possible. Homogeneous or heterogeneous catalysts can be added to steer the conversion towards the desired products and lower process temperatures. In addition to the catalysts other liquid or gaseous reactants like hydrogen or carbon monoxide might be introduced. The operation window covered in BTG facilities are pressures up to 200 bar and temperatures up to 450 °C. Depending on actual operating conditions, solvent, feedstock, other reactants and catalyst a wide range of different products can be obtained.


Liquid phase processing BTG

 BTG is one of the partners in the European Commission (EC) funded research project SusFuelCat (, in full ‘Sustainable fuel production by aqueous phase reforming – understanding catalysis and hydrothermal stability of carbon supported noble metals’.

In the EC project BTG focuses on Aqueous Phase Processing (APP; sometimes referred to as Aqueous Reforming - APR) of biomass resources. Targeted bio-products include hydrogen or (preferably) a combination of hydrogen and alkanes. The hydrogen produced can be used either directly as a fuel, or indirectly as a feedstock in a refinery producing liquid fuel.

A major characteristics and advantage of APP is the use of aqueous or water-soluble feedstock at reduced temperatures and slightly elevated pressures. Operation at such process conditions enables the processing of biomass without energy intensive drying while hydrogen can be generated in situ from biomass and in parallel from water by the Water-Gas-Shift (WGS) reaction.

APP is one of the promising techniques for advanced sustainable (liquid and gaseous) biofuel production, using catalysts as a key process component. It can be applied in combination with existing conversion technologies, such as biomass pyrolysis, to convert low value biomass into high value products, including fuels, as illustrated below. Suitable feedstocks for the APR process include sugar, sugar alcohols and oxygenates derived from biomass, as well as pyrolysis oil fractions. The process versatility, the reduced energy consumption and the product flexibility address the crucial challenges of sustainable biofuel production. Therefore APR can be considered a major technology to allow rapid industrialization of sustainable fuel production in Europe. Besides its direct use in the production of biofuel, the hydrogen can also be used to upgrade biomass blends to high quality fuels or chemicals.

Liquid phase processing BTG


Illustration of sustainable fuel production from wet biomass feedstocks and intermediates by APR as developed in SusFuelCat project (


Catalysis is key in the successful implementation of APR, and the optimisation of catalysts is expected to have a revolutionary impact on:

  • reduction of process temperature and pressure, to lower energy consumption;
  • minimization of side reactions, to increase biomass feedstock utilisation and widen the feedstock base,
  • broadening the application of the reaction products, to diversify energy vectors and chemicals,
  • increasing productivity, to decrease production site space requirements.

In SusFuelCat ten partners (six universities and research institutions, three SMEs and one multinational company) from seven countries (Germany, Finland, The Netherlands, United Kingdom, Spain, Italy, and Russia) collaborate.

Funding from the European Commission’s Seven Framework Programme (grant agreement 310490) is gratefully acknowledged.