H2Tech - Q1 2021 - 25

SPECIAL FOCUS

ADVANCES IN HYDROGEN TECHNOLOGY
achieved in this step, which contributes to
the efficiency of the SPERA process. Toluene losses within the process are minimal.
Produced methylcyclohexane is then
transported to the site of H2 use. H2 is
recovered from the methylcyclohexane
via catalytic dehydrogenation. The dehydrogenation process can be described
as follows: The methylcyclohexane feed
is vaporized in the vaporizer (11) and
super-heated in the charge heater (12)
before entering the catalyst-packed tubes
of the dehydrogenation reactor (13). This
reactor is a tubular, quasi-isothermal reactor design similar to that employed in
the hydrogenation process. The SPERA
dehydrogenation catalyst was specially
developed in-house for this process. Since
dehydrogenation is an endothermic reaction, an external heating source is required.
Typically, a hot oil system is applied (14)
to supply the necessary reaction heat.
The dehydrogenation plant is ideally colocated within an existing complex where
available waste heat at a suitable temperature level can be utilized. Reactor effluent
gas is cooled to separate H2 and condensed
toluene (16). In the reactor, methylcyclohexane is reconverted to toluene and H2.
The recovered H2 is separated from the
toluene and is subsequently compressed
and purified, if necessary, to meet relevant
product H2 specifications (18). Toluene
is then transported back to the site of the
hydrogenation plant for re-hydrogenation.
Catalyst development. Key to the success of SPERA was the development of
a dehydrogenation catalyst that was not
only robust, but also exhibited superior
selectivity and stability. As depicted in
FIG. 5, methylcyclohexane conversion of
greater than 95% was eventually achieved
at a selectivity of 99.9%, which provides
for a very low level of reaction byproducts.
Accelerated, long-term testing showed
remarkable stability even after 10,000 hr
onstream. Commercially, a catalyst life
of 2 yr could be reasonably expected.
Once a suitable candidate catalyst was
developed, the next steps to eventual
commercialization included scale-up for
manufacturing and pilot-level demo of
both the catalyst and the equipment envisioned for the SPERA process.
From April 2013-November 2014,
10,000 hr of pilot plant operation were
successfully completed, and the expected performance and life of the catalysts

Hydrogenation process
Recycle H2

H2

Dehydrogenation process

7

12

2

Toluene

14

13

Cooling
medium
4

3
1

Heating
medium

5

17
6

11

15

Product
H2
18 treatment

16
Toluene

Methylcyclohexane

SPERA H2 supply side

H2

Methylcyclohexane
SPERA H2 demand side

FIG. 4. Hydrogenation and dehydrogenation processes for the SPERA process.a

FIG. 5. Dehydrogenation catalyst development and performance.

FIG. 6. Demonstration plant in Yokohama, Japan showing dehydrogenation/hydrogenation
for the SPERA process.a

were confirmed. In the pilot-scale test
facility, methylcyclohexane and toluene
were continuously dehydrogenated and
rehydrogenated at a consistent rate of
50 Nm3/hr of H2 (FIG. 6).

Demonstration projects. Chiyoda,
along with its partners Mitsubishi, Mitsui and Nippon Yusen, established the
Advanced Hydrogen Energy Chain Association for Technology Development
H2Tech | Q1 2021 25
H2Tech - Q1 2021

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