CHEMISTRY OF BIOFUELS AND BIOFUEL ADDITIVES FROM BIOMASS - Biomass as a Sustainable Energy Source for the Future - page 567

bioethanol and FAME, a variety of biofuels have come into sight that have favorable
boiling points, polarities, energy densities, and octane and cetane numbers, such as
HMF and DMF condensates, furfural and derivatives, levulinates, and valerates.
These alternative biofuels can be produced via various routes, but the cost of these
upgrading technologies is still significant. In addition, atom efficiencies are low
(<80%), additional hydrogen is often needed, and many steps are required. Apart from
that, an even larger hurdle to be taken is the choice and pretreatment of biomass.
Suitable sugar and lignocellulose streams need to be generated that can be converted
to biofuels at reasonable costs.
The viability of this so-called platform technology will very much depend on the
concept of biorefineries, inwhich a combination of biofuels and chemicals is produced.
Notably, integration of reaction steps in which cellulose pretreatment and catalytic
conversion are conducted in one process is required in order to bring commercial
application of biofuels, other than ethanol and biodiesel, closer to the market.
After reading this chapter, the reader should be able to judge whether new biofuels
that are proposed in patents or literature can form a valuable and sustainable lead com-
pound. A convenient way to do this is from a green chemistry perspective. Is there a
real atom-efficient route and a low E-factor? Are all the parts of the biomass really
used, and are not too many steps involved? Is this biofuel a gasoline or a diesel
substitute or perhaps even a kerosene substitute? Furthermore, it is important to under-
stand the difference between a fermentation route and a catalyzed chemical reaction.
KEY CONCEPTS
Carbohydrates/sugars
Biofuels
Atom efficiency
E-factor
Platform chemical
Biofuel generations
SHORT-ANSWER QUESTIONS
18.1 Make a top 5 list of the most promising biofuels mentioned in this chapter.
18.2 What is the atom efficiency of HMF production?
18.3 What is the E-factor for HMF production when the yield is 60% (at 100%
conversion) and supposing a 1/5 water/organic mixture is used for the reaction.
Assume that maximally 80% of the solvent can be recycled and that 1 kg
glucose is dissolved in 100 l water.
18.4 Which principles of green chemistry are in accordance with the production of
biofuels?
18.5 For the production of which biofuels (e.g., from the top 5 list) is extra hydrogen
needed? Where would the hydrogen come from?