BIOBASED CHEMICALS
This conversion has the potential to be a net negative carbon process . In some applications further savings are made , for example by reduced use of fertilisers in biochar-treated soils . Nova Pangaea Technologies ’ ( NPT ) Refnova process ( Figure 1 ) provides an opportunity to convert lignocellulosic biomasses to both a monosaccharide stream and biochar . Unlike many other pyrolysis processes that generate biochar , this rapid process generates
Figure 1 - Refnova process
Figure 3 - SEM of NovaChar
a co-product that can be further converted to many base chemicals for use in sustainable products . Over the years there have been many attempts to make an economic process to convert lignocellulosic material to usable organic products . The main focus currently is to gasify the organic material to syngas , then convert this to long-chain organic products , such as renewable diesel and kerosene for sustainable aviation fuel ( SAFs ).
Figure 2 - Levoglucosan
The key issue with this process is the amount of syngas clean-up required and the high levels of energy required to make a relatively narrow range of products .
Refnova
Refnova is distinct in the use of a steam-assisted rapid pyrolysis unit . After a simple pre-treatment to reduce the particle size and reduce the level of active alkali and alkali earth metals , the biomass is entrained in a reactor with super-heated steam . This rapid increase in temperature to above 300 º C avoids many of the ring cleavage reactions that occur at lower temperatures and enables the pyrolysis reactions to begin occurring almost instantaneously . During the pyrolysis cleavage is at the glycosidic bond . This cleavage is rapidly followed by closure of the primary hydroxyl group of the sixth carbon to form a bi-ring system called levoglucosan , a dehydrated form of glucose ( Figure 2 ). Levoglucosan itself is an interesting compound , which can be used as a chiral intermediate . It is also easily converted to glucose by a hydrolysis process . This hydrolysis step has the advantage of converting any remaining cellobiose produced in the pyrolysis to glucose . The lignin portion of the feedstock is primarily converted to biochar . This is due to the decomposition of the aromatic lignin monomers . The onset temperature of the decomposition of the lignin is dependent on the metal salts present . Due to the speed of Refnova ’ s heating process , the lignin does not melt before the char processes start . This means that the original open structure of the biomass remains in the biochar ( Figure 3 ). Current trials are focused on pyrolysis of wood products and the open lumen structure gives rise to a surface area of approximately 100 m 2 / g directly out of the pyrolysis reactor with a carbon content of 75 %. This has been increased to 1,000 m 2 / g and > 90 % carbon by a further thermal activation .
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