Hydrocarbon Processing - November 2021 - 57

Sustainability
reasonable range in the actual H2
O2
production
with fixed-bed technology. Taking
the current typical fixed-bed process
as an example, if 120 g·L-1
. However, due to the above
of effective anthraquinone
is completely hydrogenated,
the theoretical hydrogen efficiency can
reach 17 g·L-1
drawbacks, it is difficult to increase the
actual hydrogen efficiency to more than
12 g·L-1
in a factory.
To minimize the degradation of work-8
g·L-1
, and the
ing liquid, the hydrogen efficiency is often
controlled at 5 g·L-1
hydrogenation degree of anthraquinone
is controlled at 40%-50%. Thereby, energy
consumption and production costs
increase. Limited by technical factors,
China's H2
bed reactor.2,3
The slurry bed
reactor lowers circulating energy
consumption, and the industrial
amplification is easily achieved
with the advantages of high
integration, simple structure and
small footprint.
2. As the core of slurry bed
technology for H2
O2 production,
a hydrogenation catalyst with high
strength and selectivity is required.
The microsphere catalyst of Pd/
Al2
O3, developed independently
O2 production has been using
fixed-bed technology for many years, and
the production capacity of a single unit
with fixed-bed technology has never exceeded
50 kt·a-1
.
The slurry bed technology for H2
O2
production shows good performance
on heat and mass transfer, and the production
capacity of a single unit with
slurry bed technology always exceeds
100 kt·a-1
technology of H2
. Compared with the fixed-bed
O2 production, the industrial
implementation of slurry bed
technology is relatively difficult. Its technical
difficulty lies in the slurry bed reactor,
high-strength microsphere catalyst
and solid-liquid separation system. Several
chemical companies (e.g., DuPont,
Solvay, Degussa, BASF) have developed
slurry bed technologies of H2
pany's slurry bed technology for H2
O2
production is shown in FIG. 1. The technology
highlights are reflected in the following
aspects:
1. It is a reaction-filtration system
with a simple structure and
outstanding performance in heat
and mass transfers. The slurry
bed reactor is equipped with a
separator on the upper section
that can avoid the air-resistor
in the conveying pipeline and
prevent the gas from entering the
filter to ensure the efficient and
stable operation of the filter. The
slurry-containing solid catalyst
particles at the bottom of the
separator flow into the filter,
and then solid catalyst circulates
back to the bottom of the slurry
Fresh H2
Anthraquinone
Slurry-bed
hydrogenator
Deionzed
water
Oxidization tower
by the authors' company, exhibits
high wear resistance, high
selectivity and high activity with
the synergistic effect of non-noble
metals.4
Industrial tests show
the hydrogenation efficiency of
the microsphere catalyst reaches
12 g·L-1
-13 g·L-1
, and no obvious
change of the catalyst has been
observed after the industrial test.
3. The proprietary oxygen-enriched
cyclic oxidation technology
improves the environmental
protection, economic benefits and
safety of the H2
O2 production
unit.5
Through a compressorassisted
cycle of the oxidation
tail gas, the tail gas emissions
in the oxidation process are
eliminated without the need for
a solvent recovery device. To
ensure constant oxygen supply, an
O2 production,
each with their own characteristics.
The schematic of the authors' comTail
gas
Recycle H2
Hydrogenated
anthraquinone
O2
oxygen-rich gas is continuously
added into the recycle gas
according to the consumption
of oxygen. At the same time, the
water brought into the oxidation
tower is reduced, and the amount
of residual liquid at the bottom of
the oxidation tower is significantly
reduced. This technology makes
the H2
O2 production greener.
4. The catalytic regeneration
technology for the working liquid
effectively converts anthrone
into anthraquinone.6,7
Compared
with traditional regeneration
technologies, the conversion
rate of the catalytic regeneration
technology is increased by 10
times. Moreover, the fully acidic
environment not only improves
the intrinsic safety of the H2
O2
production unit, but also avoids
the generation of basic alumina
solid waste.
A comparison between the authors'
O2 production and a fixed-bed techO2
production is shown
O2
procompany's
slurry bed technology for
H2
nology for H2
in TABLE 1. Compared with the fixed-bed
technology, the single-unit capacity of
the slurry bed technology for H2
duction is increased by 140%, hydrogen
(H2
) consumption per ton of product
decreased by 5%, the energy consumption
and material consumption can be
Regenerator
Dehydrating tower
Extraction tower
solution
H2
O2
Purification tower
FIG. 1. Slurry bed technology for H2
O2 production.
Hydrocarbon Processing | NOVEMBER 2021 57
Hydrocarbon Processing - November 2021

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