Separation of the primary conversion, namely the evaporation of pyrolysis oil, from the catalytic steam reforming seems to have a few advantages:

• Fixed bed commercial catalysts can be directly used which have been proven to be active and do not need additional mechanical strength for fluidization.

• Pyrolysis oil re-evaporation can be done at a lower temperature than the catalytic conversion to syngas, which is beneficial to the overall exergy efficiency of the process.

• Primary pyrolysis oil conversion seems to be mainly thermally driven, followed by catalytic gas upgrading. Actual splitting of these two processes makes separate optimization possible.

• Formed carbonaceous deposits and particles and other impurities like residual ash can be separated before the catalytic fixed bed, making energy utilization possible by burning the carbon or allowing them to gasify using steam and or CO2.

The first staged conversion of pyrolysis oil was reported and tested by Van Rossum et al4,35 where a methane free and low tar syngas was produced at ~810°C and a S/C of 1.5 (see Figure 20.6). Here an ‘inert’ fluidized sand bed was used followed by a fixed bed with a commercial catalyst. Other proposed and/or tested staged systems include the usage of a pre-catalyst (dolomite,50 char gasification enhancing,51), ‘inert’ gasification coupled with a current-enhanced catalytic reforming system52 and a pre-oxidation step to facilitate reforming.53