Catalytic conversion of biomass to fuels and commodity chemicals
Abstract
The production of biofuels from pyrolysis of biomass is one of the alternatives to fossil
fuels, but the high oxygen content, acidity and instability of the pyrolysis bio-oils still
represent a challenge limiting its widespread diffusion.
The aim of this research project focuses on develop further an existing technology to
stabilise the pyrolytic oil by hydrogenation reaction and in evaluating the economic
feasibility for industrial development.
Based on literature review, new catalysts have been synthesised and tested for the bio-oil
hydrogenation. By impregnation technique, the zirconia has been doped with Pd and not
noble metals (Cu and Fe), characterised and their performances studied, in term of
conversion and selectivity for key bio-compounds. Vanillin was completely converted
after 80 min at 100°C and 50 bar, in presence of PdFe/ZrO2. Furthermore, promising
results were obtained testing the PdFe/ZrO2 catalyst on a real water bio-oil fraction, where
the catalyst was able to maintain ~90% of carbon in the liquid phase, reduce the
polymerisation degree and the acidity of the bio-oil under mild conditions.
With the idea to minimise the hydrogen consumption and lowering the energy demand
for the hydrogenation, the reaction was carried out at low operating conditions using a
membrane reactor. A Ru–polyethersulfone (PES) catalytic membrane was synthesised
and tested for furfural hydrogenation achieving a TOF equal to 48,000 h-1
, at 70 ºC and 7
bar, but metal leaching with consequent deactivation was noticed
To address the deactivation of the Ru-PES membrane, Ra u- Polyether ether ketone
(PEEK –WC) membrane was developed using a green solvent and tested with a simulated
water bio-oil fraction at different temperature (65-85°C), pressure (11-18 bar) and H2
flow rate (5 -25 mL/min.). The PEEK-WC membrane resulted in an enhanced stability
and good hydrogenation activity.
Finally, to enhance the understanding of the real feasibility at industrial level of the
proposed biorefinery pathway (Pyrolysis/HDO), an economic feasibility study was
designed and carried out for two different scenarios: (i) using micro algae as feedstock
for producing drop-in bio-fuels, which resulted in a minimum fuel selling price of 1.418
$/L, ~ 50 % higher than fossil fuels; and (ii) pinewood bio-oil (current feedstock) orientate
to for producing chemicals (for 75% of bio oil processed) and fuels achieving an
economic potential of 38,234 MM$/y for 10Mt/y feedstock treated, suggestion a valid
alternative for green chemicals production, with relative price decrement