Plastics from Biomass

Shen L, WorreU E, Patel M (2010) Present and future development in plastics from biomass. Biofuels, Bioprod Bioreflning 4 25-40... 

Polyolefin-Based Plastics from Biomass-Derived Monomers... 

Polyolefin Plastics from Biomass and Petrochemical Technology... 

When looking at the life cycle of biodegradable plastics, two aspects are of particular importance the end-of-life options and the use of renewable resources in the material production (the major part of the currently available biodegradable plastic products are made of blends of fossil-based polymers and polymers derived from biomass). 

Renewable raw materials can contribute to the sustainability of chemical products in two ways (i) by developing greener, biomass-derived products which replace existing oil-based products, e.g. a biodegradable plastic, and (ii) greener processes for the manufacture of existing chemicals from biomass instead of from fossil feedstocks. These conversion processes should, of course, be catalytic in order to maximize atom efficiencies and minimize waste (E factors) but they could be chemo- or biocatalytic, e.g. fermentation [3-5]. Even the chemocatalysts themselves can be derived from biomass, e.g. expanded com starches modified with surface S03H or amine moieties can be used as recyclable solid acid or base catalysts, respectively [6]. 

Hydropyrolysis process gives the higher degree of mixture conversion and higher yield of light liquids as compare to pyrolysis in an inert atmosphere. Observed in some cases non-additive effects indicate that the interaction between wood and plastic derived products takes place during mixture thermal treatment. The more pronounced synergistic effects were detected for hydropyrolysis process. Iron catalysts promote the formation of liquid hydrocarbons from biomass/plastic mixtures and influence on their coit sition. 

The influence of pyrolysis temperature on the products yields was studied using mixtures of wood biomass wiA plastic (from 2 1 to 2 1 in weight ratio). The conversion degree did not change significantly with temperature variation as it was noted by other researches. Fig. I shows the main effect of temperature increase for pine wood / polyethylene co - pyrolysis within the range 360 C - 460 C is the higher amount of gas formed, whilst water fraction yield was decreased. The maximum yield of liquids (50 wt.%) was obtained at 370-400 C. 

Figure 5.1 Plastic-like materials from biomass. ( Fraunhofer ICF, 2013.)...

Basic stoichiometry teaches that for every 100 kg of polyolefin (polyethylene, PE polypropylene, PP) manufactured, a net 314 kg of CO2 is released into the environment at its end of life (100 kg of PE contains 85.7 kg carbon and upon combustion will yield (44/12) x 85.7 = 314 kg of CO2). Similarly, PET contains 62.5% carbon, which results in 229 kg of CO2 released into the environment at end of life. However, if the carbon in the polyester or polyolefin comes from biomass feedstock, the net release of CO2 into the environment is zero, because the CO2 released is sequestered in a short time period by the next crop or biomass plantation (Eigure 14.2). Thus, the fundamental value proposition for bio-based plastics arises from this intrinsic zero material carbon footprint and not necessarily from the process carbon footprint, which may be equal to or slightly better than current processes. 

Noda (1999) Films and absorbent articles comprising a biodegradable polyhydroxyatkanoate comprising 3-hydroxybutyrate and 3-hydroxyhexanoate comonomer units. US Patent 5,990,271 Noda I (2005) Plastic articles digestible by hot alkaline treatment. US Patent 6,872,802 B2 Noda I, Schechtman LA (1999) Solvent extraction of polyhydroxyalkanoates from biomass. US Patent 5,942,597... 

Synthesis gas, a mixture of mainly CO, CO2, and H2, has been used in chemical industry as feedstock and can be generated by gasification of coal and oil but also from biomass, municipal waste, or by recycling of used plastics (Kopke et al., 2010). Isobutanol production from synthesis gas has so far not been reported. However, Kopke et al. (2010) engineered Clostridium ljungdahlii, which is naturally able to use synthesis gas as carbon and energy source, for the production of 1-butanol by implementation of the CoA-dependent 1-butanol synthesis pathway from Clostridium acetobutylicum. The final titer of about 0.5 mM 1-butanol was rather low however, this approach demonstrated the feasibility to produce fuels and chemicals from synthesis gas. 

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