What are bio-based chemicals?
So far, the production of chemicals has mainly been based on fossil fuels such as crude oil, coal or natural gas. Fossil resources, however, are limited and, not only in their combustion but also in their processing, increase the concentration of greenhouse gases in the atmosphere. Millions of stored carbon get back into the material cycle. First of all, this carbon is bound for a while in the chemicals and the products produced from them. In the longer term, however, these substances and products are again degraded or incinerated as part of the material cycle and release additional carbon dioxide.
In order to contain global warming, fossil raw materials must therefore be replaced by renewable raw materials. At the same time, this need also arises from the fact that fossil resources are scarce and increasingly difficult to mine. The future lies in the bioeconomy, where nature replaces the chemical factory.
At present, strategies are being developed worldwide for how to make the transition from conventional to bio-based chemistry. For example, the states of the European Union have set themselves the goal of reducing greenhouse gas emissions by 40 percent by 2030 compared to 1990 levels. One requirement is that by 2020 at least 20 percent of the materials would have to be bio-based. This share should then increase to 25 percent by 2030. Bio-based chemistry uses new production methods based on the use of biomass from renewable raw materials.
As early as 2004, 12 basic chemicals for the chemical industry were named by the National Renewable Energy Laboratory NREL, which can also be produced biochemically. In the EU, the RoadToBio project launched in 2017 also lists 120 biobased chemicals with economic potential. There is an intersection of chemicals that appear in both lists. These include succinic acid, para-xylene, propylene glycol and glycerin.
Succinic acid, also known as succinylic acid, is mainly produced from petroleum-derived substances and is used mainly for the synthesis of specialty chemicals. However, it also has the potential to serve as a raw material for polyurethane. Succinylic acid can also be produced biotechnologically by fermentation of carbohydrates. Various chemical companies expect succinylic acid to become a so-called platform chemical in the future, enabling it to produce a huge range of products.
An important chemical is also para-xylene. It serves as a starting material for the production of polyesters whose main representative is polyethylene terephthalate (PET). In turn, PET bottles, fibers and films are produced from PET. Para-xylene has hitherto been obtained from petroleum-based hydrocarbon mixtures. The mixtures of hydrocarbons can also be produced by chemical degradation of cellulose or lignin. Furthermore, sugar is first converted to isobutanol by yeast fermentation. Isobutanol then serves as the starting material for the production of para-xylene.
Propylene Glycol and Glycerine are also becoming basic chemicals for many chemical syntheses. Conventionally, propylene glycol is recovered from propylene. It can also be made from bio-based glycerol by reduction with metal catalysts. Glycerin is already produced mainly bio-based today. It is produced in the context of biodiesel production by the esterification of vegetable oils with alcohol as a by-product.
Finally, new production processes are being developed that use bio-based chemicals without equivalent in conventional chemistry.