Hydrocarbon Processing - November 2021 - 56

Sustainability
B. ZONG, Y. SHI and B. SUN,
Sinopec, Beijing, China
H2O2 and its hydrocarbon nitridation/oxidation
to produce caprolactam and propene oxide
Traditional hydrocarbon nitridation
and oxidation technologies, such as
caprolactam (CPL) and propene oxide
production technologies, present low
atom utilization and serious environmental
pollution problems. An urgent
need exists for green hydrocarbon oxidation
and nitridation technologies. As
a well-known green oxidant, hydrogen
peroxide (H2
O2) is widely used in green
hydrocarbon oxidation and nitridation,
with water as the only byproduct.
However, the low capacity of one
single fixed-bed unit of anthraquinone
hydrogenation for H2
O2 production-
O2
,
which is widely adopted in China-has
severely restricted the supply of H2
further hampering the development of
the green chemical industry in China.
The authors' company endeavors to
develop slurry bed technology of H2
O2
production to promote production capacity,
reduce production costs and
environmental pollution. Furthermore,
green production technologies of CPL
and propene oxide with H2
O2 have also
been developed. The nitrogen atom
utilization was enhanced from 60% to
nearly 100%, and the carbon atom utilization
was also promoted from 80% to
nearly 100%.
Basic organic chemicals, organic intermediates
and fine chemicals usually
contain nitrogen or oxygen atoms, and
their production involves hydrocarbon
nitridation or oxidation reactions. Traditional
nitridation or oxidation reactions
have poor atom utilization, and cause
serious pollution due to the unsatisfactory
oxidants that are used, such as dichromate,
permanganate, hypochlorite
and nitric acid. Ammonia (NH3
) is the
fundamental source of nitrogen atom in
hydrocarbon nitridation reactions, but it
56 NOVEMBER 2021 | HydrocarbonProcessing.com
must experience the oxidation process
to be converted into nitric acid, hydroxylamine,
azide or highly toxic cyanide to
participant in traditional hydrocarbon
nitridation reactions. These complicated
processes bring huge energy consumption
and pollutants emissions. For example,
more than 300 kt of nitrogen oxides
(NOx
) are emitted in the NH3
oxidation
process used in nitric acid production
each year.1
oxidant or active N-containing agent is
central to promoting nitrogen or carbon
atom utilization, and eliminate the generation
of pollutants.
As an environment-friendly oxidant,
H2O2 is widely used in the chemical industry,
bleaching processes, wastewater
treatment, exhaust air treatment and for
various disinfection applications. Considering
the transportation risks and
costs of H2
H2O2 production unit to support the opO2
production units
eration of the green chemical production
unit. At least two H2
adopting fixed-bed technology should be
constructed to support the normal operation
of a 300 kt·a-1
O2
propene oxide green
production unit, significantly increasing
construction and operating costs. Conversely,
green hydrocarbon nitridation or
oxidation technologies with H2
as the
oxidant are developing rapidly around
the world. China should also develop
green chemical technologies with independent
intellectual property rights to
solve environmental pollution problems
in its self-development process.
The authors' company has been working
for more than 20 yr to develop the slurry
bed technology for H2
O2 production
with completely independent intellectual
property rights, supporting China's green
chemical industry development.
Therefore, the selection of
Slurry bed technology of H2O2
production.
The industrial production of
H2
O2 widely adopts the anthraquinone
hydrogenation method due to its advantages
in industrial efficiency, environmental
protection and economic benefits. Its
production process includes anthraquinone
hydrogenation, hydrogenated anthraquinone
oxidation, H2
O2
extraction
and anthraquinone working liquid purification.
Two anthraquinone hydrogenation
technologies are now in use: fixedbed
technology and slurry bed technology.
The industrial production of H2
O2 is also
done with these two technologies.
Compared with the slurry bed techO2
production, the fixednology
for H2
O2, the factory must build an
bed technology is easy to implement and
the catalyst does not need to be separated.
It also has the following drawbacks:
1. Heat transfer performance is
poor. As the anthraquinone
hydrogenation reaction is an
exothermic reaction, local hot
spots or flying temperatures occur
in the fixed bed. The working
liquid degrades easily in the
high-temperature area, resulting
in poor selection performance
and poor product quality of the
reaction, which causes subsequent
processing problems and limits the
capacity of the production unit.
2. Catalysts with a fine particle size
cannot be used, so the inner surface
with active sites is not fully utilized,
resulting in low catalyst utilization
efficiency. More importantly, the
hydrogenation reaction is limited
by heat and mass transfer.
To avoid excessive hydrogenation of
the working liquid, the hydrogenation
degree and hydrogen efficiency of anthraquinone
are generally controlled within a
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