Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 1, pp. 69−79.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
A.S. Dykman, N.S. Imyanitov, S.A. Polyakov, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 1, pp. 70−79.
ORGANIC SYNTHESIS AND INDUSTRIAL
Homogeneous Stationary Catalysis
A. S. Dykman, N. S. Imyanitov, and S. A. Polyakov
All-Russia Research Institute of Petrochemical Processes, St. Petersburg, Russia
Eurochim–SPb-Trading, St. Petersburg, Russia
Received April 22, 2008
Abstract—Concept of stationary homogeneous catalysis is formulated. According to this concept, a catalyst solution
is permanently present within the reactor and the product is removed from the reactor in the form of a gas (vapor)
or a stratifying fluid (solution). This technology combines advantages of the homogeneous and heterogeneous
catalyses. Some approaches to development of the technology under consideration are presented.
Owing to their molecular (ionic) nature, homogeneous
catalysts exhibit high activity, selectivity, and reproduc-
ibility. In a homogeneous system, it is easier to perform
heat and mass transfer, which is particularly important
when carrying out reactions in industrial apparatus.
A fundamental disadvantage of homogeneous catalysts
is that they should be separated from the reaction product
and regenerated (or newly synthesized) after each
From this standpoint, heterogeneous catalysts have
an apparent advantage. Therefore, much effort is applied
and money invested to attempts to create catalysts that
would combine advantages of the homogeneous and
The simplest way to heterogenize a homogeneous
catalyst is to deposit it onto a support as a ﬁ lm. In this way,
the catalyst “Polyphosphoric acid on silica gel” (PPA-S),
used for oligomerization of propylene, is manufactured*.
However, ﬁ lm-type systems rapidly lose their activity
because the catalyst is carried away by the flow of
raw materials and products . Therefore, researchers
started to ﬁ x active groups to the support by chemical
bonding. The best known among catalysts of this kind is
a copolymer of styrene and divinylbenzene with sulfuric
acid groups (KU-2, Amberlyst).
At the end of the last century, researchers spent
several decades for heterogenization of metal-complex
catalysts [2–8]. However, complexes “sewn” to a solid
support were, as a rule, “washed away” in the course
of a reaction [7, 8]. Frequently, systems of this kind
combined disadvantages, rather than advantages of both
kinds of catalysis.
It should be noted that even the best of heterogenized
catalysts cannot, in principle, obviate problems associated
with hindrances to heat and mass transfer, caused by
introduction of a solid phase into the reaction zone.
However, several processes have been developed in which
the advantages of the heterogeneous and homogeneous
catalyses could be fully combined. Some of these
processes have been implemented on a large industrial
scale. It seems to be of use, for development of studies in
this promising area, to consider characteristic examples of
processes of this kind with emphasize on the conditions
required and ways to create these conditions.
The technology of processes of this kind is very simple:
a solution of a homogeneous catalyst is permanently
situated within a reactor into which raw materials are
fed; the reaction product is discharged in the form of
a gas (vapor) or as a ﬂ uid (solution) stratifying from the
We ﬁ rst consider several industrially implemented
on a large scale or promising processes with stationary
Synthesis of acetaldehyde by oxidation of ethylene
and hydration of acetylene. Acetaldehyde is produced by
oxidation of ethylene by passing a mixture of ethylene
and oxygen through an aqueous solution of the catalyst
at 90–130°C and 0.3–1 MPa:
* It should be speciﬁ ed that many catalysts based on phosphoric acid
and various modiﬁ cations of silicon oxide contain no free phosphoric
acid and do not belong to the type under consideration .