Branched-Chain Higher Alcohols - Biotechnology in China: Biofuels and Bioenergy - page 105

product categories, including cosmetics, perfumes, flavorings, inks, solvents, and
resins. For fuel oxygenates, BCHAs are flexible chemicals with properties that
allow blending with both gasoline and diesel fuels.
Based on an average selling price of $781 per ton, the fuel additive market in
China exceeded $1.5 billion in 2007, with an expected growth rate of over 17%
annually, which will drive the market to over $17.6 billion by 2022 [ 16 , 17 ].
Currently, China is the world's largest MTBE market, with 87% being used as a
gasoline additive in 2007 [ 18 , 19 ]. The fuel additive market in China is driven by
the demand for gasoline. China's demand for gasoline has grown substantially and
is expected to continue to grow in double digits owing to the rapid increase in the
number of automobiles. In any event, there is little doubt that China will continue
to increase its reliance on oil, and gasoline usage will continue to grow dramati-
cally. Market demand for MTBE or alternative fuel additives will be significant.
Therefore, there is reason to assume that BCHAs might replace MTBE in the fuel
additive market.
2.2 Isopropanol
Isopropanol can be used directly as a fuel supplement added to gasoline or as a
feedstock for the transesterification of fats into biodiesel. The use of diisopropyl
ether as a fuel oxygenate may become a significant outlet for isopropanol [ 20 ]. It is
estimated that the demand for isopropanol in China will increase at a rate of
8-10% in the next 5 years and the production capacity is expected to be 230,000 t
in 2015, indicating a high market potential [ 21 ].
There are two commercial routes for manufacturing isopropanol by combining
water and propylene to produce it. The indirect method is based on the hydration
of refinery-grade propylene using sulfuric acid to form isopropyl sulfate, which is
then hydrolyzed with steam to form sulfuric acid and isopropanol. The crude
isopropanol is distilled to the desired purity. The indirect process can use refinery-
grade propylene streams and lower operating pressures than the direct process, but
suffers from higher corrosion and maintenance costs. Owing to the complicated
process and the problem of a high level of pollution, this method was abandoned in
the 1980s. Instead, the direct hydration of chemical-grade (90-99%) propylene
without sulfuric acid consumption was developed. Propylene and water are heated
and the liquid-vapor mixture under pressure passes into a trickle-flow reactor
containing sulfonated polystyrene cation ion-exchange resins. Alternatively, the
reaction can be performed in the gas phase over a phosphoric acid based fixed-bed
catalyst. The main limitation of the model route is the high energy consumption
[ 21 ]. Besides, isopropanol can also be produced by the hydrogenation of acetone in
the liquid phase. This process is only suitable when excess acetone is available.
China started its isopropanol industry rather early. Jinzhou Petrochemical
Company, China National Petroleum Corporation (CNPC), constructed a 20,000
t/year isopropanol unit with the propylene vapor-phase hydration process in 1977.