Chemistry Reference
In-Depth Information
Fig. 1 Production as share of consumption for coal, natural gas and petroleum in the
United States.
2
and other petroleum-based fuels from 86.1 million barrels per
day in 2007 to 110.6 million barrels per day in 2035.
3
To satisfy this
increase in world liquids demand, liquids production is projected
to increase by 26 million barrels per day from 2007 to 2035.
3
This
includes the production of both conventional liquid supplies (crude
oil, natural gas, and refinery liquids) and unconventional supplies
(biofuels, oil sands, extra-heavy oil, coal-to-liquids, gas-to-liquids, and
shale oil).
3
World oil prices reached historically high levels in 2008, mainly
because of a strong increase in demand for transportation fuels,
particularly in emerging non-OECD economies.
3
The sustained high
world oil prices encourage the development of economically competitive
unconventional resources and the use of enhanced oil recovery tech-
nologies to increase production of conventional resources. This suggests
the necessity of innovative research for the cost-effective conversion of
domestic coal/biomass reserves into clean fuels.
Alternative fuels, particularly C
2
þ
alcohols, have been studied
extensively in the recent years as clean, sustainable and transportable
fuel alternatives.
1,4
C
2
þ
alcohols are desirable since they serve as a clean
alternative fuel,
5-7
a gasoline blend, and as a hydrogen carrier to supply
fuel cells.
8,9
The major routes to produce C
2
þ
alcohols are categorized as
biochemical and thermochemical routes. The biochemical route involves
the fermentation of sugars derived from corn or sugarcane
8-14
and the
thermochemical route is mainly gasification of biomass, coal or natural
gas to produce a gaseous mixture called synthesis gas (or syngas) which
can then be catalytically converted to ethanol and other higher alcohols.
8
Biochemical processes result in higher selectivities toward specific end
products, but their reaction rates are orders of magnitude lower than that
of the thermochemical processes, and the product is an aqueous mixture
that must be separated before it can be used. Thus the thermochemical
routes to produce higher alcohols are more economically competitive.
8
