formed by dehydration of simple carbohydrates such as fructose. A catalyst with acid groups and which is water-tolerant such as a is used. HMF can be converted into dimethylfuran,
Synthesis gas is converted into a hydrocarbon wax (a mixture of long-chain alkanes) by heating it and passing the vapour over a cobalt catalyst (the Fischer-Tropsch process) (Figure 2, route 5). The (SMDS) is a modern development of this process. The hydrocarbon waxes are subsequently catalytically cracked with excess hydrogen () (Figure 2, route 9) to form smaller alkanes, for example:
Any solid biomass including for example agricultural, city and industrial waste can be used to make synthesis gas using techniques similar to its production from . More recent developments includes a plant in the Netherlands, which is using liquid propane-1,2,3-triol (glycerol), a by-product from the production of , from animal fats and vegetable oils.
Another way to produce propene is via methanol (produced from biomass via synthesis gas), which is an example of the MTO (Methanol To Olefins) process. (Olefin is the older name for the homologous series, alkenes). Methanol can be converted into high purity ethene and propene via dimethyl ether (Figure 3, routes 10 and 9). Methanol vapour is passed over alumina at ca 600 K. An equilibrium mixture of methanol, dimethyl ether and steam is produced, containing about 25% methanol: