Environmental Engineering Reference
In-Depth Information
4.8 Example Platform Molecules
For platform molecules to offer value to the bio-based chemical industry they
need to be useful in the formation of marketable chemicals. While all of the
platform molecules listed in Table 4.5 are actually or potentially useful, in the
following we describe one mainstream representative from each of the four
biomass-processing routes. In each example, a set of possible derivatives is
provided and discussed. The suggested products in each case are not exhaustive;
instead, they are representative of the potential of that molecule to be converted
into a diverse range of higher-value chemicals and materials, representing the full
range of chemical transformations for the different functional groups of each plat-
form molecule. These four examples have been selected as they represent what the
authors consider to be the current platforms or platform molecules of exceptional
promise for each of the processing technologies, with well-established production
routes from biomass and numerous investigated products for each.
4.8.1
Synthesis Gas Platform: Thermal Treatment
The thermal/thermochemical treatment of biomass is viewed as one of the primary
platforms for the biorefinery [126]. Included within the thermal treatment of
biomass is the syngas platform. The syngas platform can be used to produce fuels,
chemicals and energy via the intermediate H
2
, CO
2
and CO constituents, while the
broader thermal treatment platform additionally includes the generation of bio-oil
and bio-char (Figure 4.14). Although possibly utilised as an energy source for the
biorefinery, the nutrient-rich bio-char has also shown promise as soil amendment/
enhancer, while additionally acting as a means of carbon sequestration [127-130].
Bio-oil can be used directly as a source of energy [131] or for syngas production
[132]. It can also be steam reformed to give bio-hydrogen [133] or catalytically
upgraded to a transportation fuel [134-136]. Bio-oil contains some potential
platform molecules, such as furfural, levoglucosan, alcohols and various phenolics,
though the complex mixture of the oil means purification costs are high and yields
of individual components are low [137]. Although bio-oil and bio-char are impor-
tant products from the thermal treatment of biomass, it is therefore likely that the
use of synthesis gas will prove to be the favoured route to platform molecules.
Synthesis gas (syngas), primarily a mixture of CO and H
2
, can be prepared from
any carbonaceous material via controlled thermal treatment (>700°C) in the
presence of oxygen and/or steam, a process generally referred to as gasification.
Both the production and subsequent utilisation of syngas is well established, with
commercial facilities using coal feedstocks dating back to the early 1800s [138].
Although initially used as a fuel (town gas) during the First and Second World
Wars, technology advanced for the conversion of synthesis gas to other mainstream
chemicals such as MeOH, olefins, alkanes, ethers and ammonia. The drive towards
a bio-based economy has resulted in renewed interest in the biomass gasification,
