Chemical Engineering December 2010 - 11

Edited by Gerald Ondrey
December 2010
Scaleup for a new process
to make Bio-Alkylate
N
ext spring, Exelus, Inc. (Livingston, N.J.;
www.exelusinc.com) plans to pilot a new
process that converts crude bioethanol (beer)
into Bio-Alkylate - a fuel that is chemically
identical to gasoline. New Renewable
Fuel Standards (RFS) of the U.S. Environmental
Protection Agency (EPA; Washington,
D.C.) call for increasing the amount of
ethanol that can be added to gasoline to 15
vol.% (so-called E15 gasoline), which would
require significant engine modifications.
" This technology eliminates the limitations
of using bio-ethanol as a fuel by allowing
gasoline blends up to E50 without requiring
any changes to cars or fuelling stations or
compromising mpg " , says Exelus president
Mitrajit Mukherjee.
In the new process (flowsheet), filtered
beer is first vaporized in a stripping column,
generating wet ethanol vapor. The vapor is
heated further and dehydrated into ethylene
over a solid-acid catalyst. Upon cooling,
the water and ethylene are readily phase
separated. Crude ethylene is then directly
alkylated with excess isobutane over an
engineered, zeolite catalyst producing BioAlkylate.
Unreacted isobutane is distilled
and recycled.
In laboratory trials, the in-house-developed
catalyst showed exceptional activity for
converting ethylene into high-octane, lowRVP
(Reid vapor pressure) alkylate, with
Stripping
column
Crude ethanol
Dehydration
reactor
Bio-alkylation
reactor
Crude
ethylene
Distillation
column
Makeup
isobutane
Fermentation
beer
Fired
heater
Water
Water
an olefin conversion near 100%. Mukherjee
points out that the rates of reaction over this
catalyst greatly exceed that reported in the
literature for solid-acid catalysts, and avoids
the hazards and costs associated with conventional
isoparaffin-alkylation processes
that are based on HF or H2SO4 liquid catalysts.
Up to now, there are no commercial
technologies capable of isoparaffin alkylation
using ethylene, he says.
The new process is being developed with
partial funding ($1 million) from the U.S.
Dept. of Energy's (DOE; Washington, D.C.)
ARPA-E program, and a 1-gal/d pilot plant
is being planned to start up next spring.
Mukherjee estimates the cost of producing
Bio-Alkylate at $2/gal (without price credits
for ethanol).
A new catalyst reduces SO2 emissions from H2SO4 plants
A
Hansen, general manager - sulfuric
acid, catalyst division.
Conventional sulfuric-acid catalysts
are based on vanadium oxides promoted
with alkali-metal sulfates on an inactive,
porous silica support. In these so-called
supported liquid phase (SLP) catalysts,
the oxidation of SO2 occurs as a homogeneous
reaction in a liquid film covering
the internal surface of the supported
material. Although the detailed reaction
mechanism is not entirely known,
there is evidence that only the oxidation
state V+5 is active. With Leap5 technology,
Topsøe has substantially increased
the amount of V+5 to about 70% of the
total vanadium content (at 400-440°C)
Catalyst recycling
A new process for selectively
dissolving either palladium
or gold from mixed-metal
catalyst systems could offer
a way to improve recycling of
those materials. In traditional
noble-metal recycling with
aqua regia (mixture of nitric
and hydrochloric acids),
metals are often dissolved
together, which introduces
impurities into the recycled
metals. Now scientists at the
Georgia Institute of Technology
(Atlanta, Ga.; www.
gatech.edu) have developed
(Continues on p. 12)
t last month's Sulfur 2010 Conference
(November 1-4; Prague, Czech
Republic), Haldor Topsøe A/S (Lyngby,
Denmark; www.topsoe.com) introduced
its latest sulfuric-acid catalyst, VK-701
Leap5, which promises to help operators
of sulfuric acid plants meet morestringent
SO2-emission limits. When
used in the final pass of single absorption
H2SO4 plants, VK-701 Leap5 reduces
SO2 emissions by up to 40% compared
to existing catalysts. The new
catalyst also makes it possible to reach
down to 50 ppm in existing 3+1 doubleabsorption
plants or to design doubleabsorption
plants with SO2 emissions
as low as 20-50 ppm SO2, says Lene
- about two to three times more than
existing commercial catalysts, says
Hansen. The activity of VK-701 operating
at high conversion in a gas feed with
10 vol.% SO2 and 10 vol.% O2 is about
two times higher than standard cesiumpromoted
catalysts over the temperature
range of 380-460°C.
The first industrial installation of
VK-701 was a single-absorption plant
burning elemental sulfur and operating
with a five-bed SO2 converter. Replacing
the Cs- and K-promoted catalysts
in the final passes (beds four and five)
led to a 35% reduction in SO2 emissions
at the same production rate (245 metric
tons per day H2SO4).
Note: For more information, circle the 3-digit number
on p. 58, or use the website designation.
ChemICAl eNGINeerING www.Che.Com DeCember 2010 11
http://www.exelusinc.com http://www.gatech.edu http://www.topsoe.com http://www.Che.Com
Chemical Engineering December 2010

Table of Contents for the Digital Edition of Chemical Engineering December 2010
