542
ORNL-Vertimass Process
Oak Ridge National Laboratory (ORNL) has developed highly versatile process and
catalyst [262] for single-step conversion of dilute ethanol from fermentation stream
to highly value-added product stream consisting of blend stocks suitable for jet fuel,
middle distillate or gasoline. The process is capable of using feedstocks containing
5–100% ethanol in water without external supply of hydrogen and under mild conditions, at low pressure, 60 psi, 350 °C and optimum space velocity (LHSV). Pilotscale evaluation of the process is to be undertaken by TechnipFMC, and the lab-scale
process has been licensed to Vertimass for exploring commercial venture [263–266].
V-, V-In- and Ga-exchanged mono- and bimetallic ZSM-5 catalysts, under optimized process conditions, display C 3 –C 16 hydrocarbon selectivity >80% (Fig. 27)
with 100% conversion of ethanol. Light hydrocarbons (C 2 + C 3 ) formation is <5%
[267–269]. Metal-exchanged zeolite catalyst in combination with a benzene alkylation catalyst helps to bring down benzene content to <0.68% in the product stream
[270], in accordance with environmental regulations.
In order to gain mechanistic insights into the process, studies have been conducted using deuterium-labelled reactants, C 2 H 5 OD and D 2 O and in situ DRIFTS
studies [267]. It is observed that with C 2 H 5 OD as reactant, deuterium is incorporated in product hydrocarbons, but with 70% ethylene and 30% D 2 O, deuterium
incorporation is not observed. But with 70% ethanol and 30% D 2 O, deuterium is
incorporated in all hydrocarbons except ethylene. Based on these results and
DRIFTS studies, Chaitanya et al. [267] concluded that ethylene is not the intermediate in this process and the reaction proceeds via hydrocarbons pool mechanism.
It is proposed that, unlike LT-PNNL multistep process, which involves ethanol
dehydration to ethylene and oligomerization of ethylene to higher carbon number
olefins followed by hydrogenation, ONRL-Vertimass process on metal-exchanged
zeolite catalysts follows a consolidated alcohol dehydration-oligomerization
(CADO) pathway to yield, in single step, hydrocarbon blend stocks, suitable for jet
Fig. 27 Ethanol
conversion on V-ZSM-5
catalyst as a function of
temperature at
LHSV-2.93 h
−1
(Reproduced from Narula
et al. [267])
R. Vinayagamoorthi et al.
ORNL-Vertimass Process
Oak Ridge National Laboratory (ORNL) has developed highly versatile process and
catalyst [262] for single-step conversion of dilute ethanol from fermentation stream
to highly value-added product stream consisting of blend stocks suitable for jet fuel,
middle distillate or gasoline. The process is capable of using feedstocks containing
5–100% ethanol in water without external supply of hydrogen and under mild conditions, at low pressure, 60 psi, 350 °C and optimum space velocity (LHSV). Pilotscale evaluation of the process is to be undertaken by TechnipFMC, and the lab-scale
process has been licensed to Vertimass for exploring commercial venture [263–266].
V-, V-In- and Ga-exchanged mono- and bimetallic ZSM-5 catalysts, under optimized process conditions, display C 3 –C 16 hydrocarbon selectivity >80% (Fig. 27)
with 100% conversion of ethanol. Light hydrocarbons (C 2 + C 3 ) formation is <5%
[267–269]. Metal-exchanged zeolite catalyst in combination with a benzene alkylation catalyst helps to bring down benzene content to <0.68% in the product stream
[270], in accordance with environmental regulations.
In order to gain mechanistic insights into the process, studies have been conducted using deuterium-labelled reactants, C 2 H 5 OD and D 2 O and in situ DRIFTS
studies [267]. It is observed that with C 2 H 5 OD as reactant, deuterium is incorporated in product hydrocarbons, but with 70% ethylene and 30% D 2 O, deuterium
incorporation is not observed. But with 70% ethanol and 30% D 2 O, deuterium is
incorporated in all hydrocarbons except ethylene. Based on these results and
DRIFTS studies, Chaitanya et al. [267] concluded that ethylene is not the intermediate in this process and the reaction proceeds via hydrocarbons pool mechanism.
It is proposed that, unlike LT-PNNL multistep process, which involves ethanol
dehydration to ethylene and oligomerization of ethylene to higher carbon number
olefins followed by hydrogenation, ONRL-Vertimass process on metal-exchanged
zeolite catalysts follows a consolidated alcohol dehydration-oligomerization
(CADO) pathway to yield, in single step, hydrocarbon blend stocks, suitable for jet
Fig. 27 Ethanol
conversion on V-ZSM-5
catalyst as a function of
temperature at
LHSV-2.93 h
−1
(Reproduced from Narula
et al. [267])
R. Vinayagamoorthi et al.