543
fuel, diesel and gasoline. Product stream composition could be varied depending on
market demands by suitable optimization of the process conditions. The lab-scale
process has been demonstrated by 200 h continuous run, and the product composition and fuel characteristics have been established. However, long-term stability of
the catalyst and ASTM-D-7566 certification are yet to be established. Technoeconomic and life cycle analysis [271] of ONRL-Vertimass vs. LT-LNNL processes
has shown that the former one is cost-efficient, is viable for blending when oil is at
US$100 per barrel and can reduce GHG emissions by 40–96%. Vertimass along
with Bioenergy Technology Office of the US Department of Energy would jointly
work for further improvements in the process and catalysts and to establish commercial viability.
C 4 Bio-alcohols-Based Processes
Two C 4 bio-alcohol-based processes, one by Gevo, Inc., using bio-isobutanol and
the other by Cobalt Biofuels (now Cobalt Technologies) using bio-1-butanol, for
conversion to jet fuel, have been developed. Sugars extracted from biomass undergo
fermentation by Gevo Integrated Fermentation Technology (GIFT) using specific
microorganisms to yield isobutanol [272], which is dehydrated to isobutylene. On
oligomerization using acidic catalysts like Amberlyst 35, iso-butylene is converted
to C 8 –C 16 olefins, which are subsequently hydrogenated to jet fuels [273]. Jet fuel
blend from Gevo process has secured certification as per ASTM-D-7566 for blending with commercial aviation fuel. Airliner Delta has entered into an agreement
with Gevo, Inc., for offtake of 10 mill gallons per year of bio-jet fuel [274].
CLJ-5 bio-jet fuel developed by Cobalt Biofuels is based on 1-butanol obtained
by fermentation of C 5 –C 6 sugars extracted from cellulosic biomass [275–277].
Bio-1-butene produced by dehydration of bio-1-butanol undergoes oligomerization
followed by hydrogenation to yield jet fuels. Oligomerization is achieved by using
metallocene catalyst, bis-cyclopentadienyl zirconium dichloride, with MAO as cocatalyst [278]. The process has been demonstrated at pilot scale, and the jet fuel
product meets all specifications for blending with JP-5 and other aviation fuels.
Other Processes Based on Ethanol/Alcohols
Conversion of ethanol to butanol and higher alcohols through Guerbet chemistry
has opened up another route for ethanol to jet fuel (ETJ) production [241], wherein
C 4 –C 6 alcohols could undergo sequential dehydration, oligomerization and hydrogenation to yield jet fuels. With Cu/MgO-Al 2 O 3 catalyst, PNNL [279] could achieve
44% ethanol conversion and 75% C 4 + alcohol selectivity at 300–350 °C and WHSV
0.1–0.2 h
−1
. However, achieving higher ethanol conversion with high selectivity for
C 4+ alcohols and longer life has been a challenge for ethanol coupling processes.
Hence many options for [241] ETJ process are being explored as illustrated in
Fig. 28. A combination of two methanol conversion steps, the first through MTO
Catalytic Conversion of Alcohols into Value-Added Products
fuel, diesel and gasoline. Product stream composition could be varied depending on
market demands by suitable optimization of the process conditions. The lab-scale
process has been demonstrated by 200 h continuous run, and the product composition and fuel characteristics have been established. However, long-term stability of
the catalyst and ASTM-D-7566 certification are yet to be established. Technoeconomic and life cycle analysis [271] of ONRL-Vertimass vs. LT-LNNL processes
has shown that the former one is cost-efficient, is viable for blending when oil is at
US$100 per barrel and can reduce GHG emissions by 40–96%. Vertimass along
with Bioenergy Technology Office of the US Department of Energy would jointly
work for further improvements in the process and catalysts and to establish commercial viability.
C 4 Bio-alcohols-Based Processes
Two C 4 bio-alcohol-based processes, one by Gevo, Inc., using bio-isobutanol and
the other by Cobalt Biofuels (now Cobalt Technologies) using bio-1-butanol, for
conversion to jet fuel, have been developed. Sugars extracted from biomass undergo
fermentation by Gevo Integrated Fermentation Technology (GIFT) using specific
microorganisms to yield isobutanol [272], which is dehydrated to isobutylene. On
oligomerization using acidic catalysts like Amberlyst 35, iso-butylene is converted
to C 8 –C 16 olefins, which are subsequently hydrogenated to jet fuels [273]. Jet fuel
blend from Gevo process has secured certification as per ASTM-D-7566 for blending with commercial aviation fuel. Airliner Delta has entered into an agreement
with Gevo, Inc., for offtake of 10 mill gallons per year of bio-jet fuel [274].
CLJ-5 bio-jet fuel developed by Cobalt Biofuels is based on 1-butanol obtained
by fermentation of C 5 –C 6 sugars extracted from cellulosic biomass [275–277].
Bio-1-butene produced by dehydration of bio-1-butanol undergoes oligomerization
followed by hydrogenation to yield jet fuels. Oligomerization is achieved by using
metallocene catalyst, bis-cyclopentadienyl zirconium dichloride, with MAO as cocatalyst [278]. The process has been demonstrated at pilot scale, and the jet fuel
product meets all specifications for blending with JP-5 and other aviation fuels.
Other Processes Based on Ethanol/Alcohols
Conversion of ethanol to butanol and higher alcohols through Guerbet chemistry
has opened up another route for ethanol to jet fuel (ETJ) production [241], wherein
C 4 –C 6 alcohols could undergo sequential dehydration, oligomerization and hydrogenation to yield jet fuels. With Cu/MgO-Al 2 O 3 catalyst, PNNL [279] could achieve
44% ethanol conversion and 75% C 4 + alcohol selectivity at 300–350 °C and WHSV
0.1–0.2 h
−1
. However, achieving higher ethanol conversion with high selectivity for
C 4+ alcohols and longer life has been a challenge for ethanol coupling processes.
Hence many options for [241] ETJ process are being explored as illustrated in
Fig. 28. A combination of two methanol conversion steps, the first through MTO
Catalytic Conversion of Alcohols into Value-Added Products