1070-4272/05/7801-0113C2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 1, 2005, pp. 113!119. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1,
2005, pp. 114!121.
Original Russian Text Copyright + 2005 by Kondrat’ev, Ivanchev.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Optimization of Polymerization in Autoclave
and Tubular Reactors
Yu. N. Kondrat’ev and S. S. Ivanchev
Central Research Institute of All-Round Automation, Joint-Stock Company, St. Petersburg, Russia
St. Petersburg Branch, Boreskov Institute of Catalysis, Siberian Division, Russian Academy of Sciences,
St. Petersburg, Russia
Received May 14, 2004
Abstract-The possibilities of improving operation of one-zone autoclave and tubular reactors using approp-
riate initiating systems without changes in the reactor design and process scheme were analyzed and experi-
mentally tested on pilot and industrial installations for high-pressure polymerization of ethylene.
Despite rapid development of processes for catalyt-
ic polymerization of ethylene at low pressures in
the gas phase and solution, high-pressure polymeriza-
tion of ethylene is still of industrial importance. At
present, nearly 25% (~22 million tons per year) of the
total production volume of polyolefins (~84 million
tons) is produced using high-pressure autoclave and
tubular reactors. Thus, the improvement of operation
of reactors for high-pressure polymerization of ethyl-
ene, especially without changes in the reactor design
and process scheme, is an urgent problem.
In this paper we analyzed the possibility of im-
proving the operation of high-pressure autoclave and
tubular reactors without changes in the reactor design
and process scheme, on the basis of the analysis of
the operation conditions and mechanism of polymeri-
zation as influenced by various initiating systems
(peroxides and their mixtures, and mixtures of per-
oxides and oxygen).
The structure of peroxide initiator determines its
important properties and feasibility of its use .
The later notion involves: (1) kinetic characteristics,
operation temperature range, and performance;
(2) solubility in oils (hydrocarbons) and thus simplic-
ity of supply into the reactor; (3) absence of corrosion
effect on the installation; (4) safe use and storage; and
(5) hygienic, sanitary, and toxicological properties.
These requirements were used in selection of per-
oxides recommended for high-pressure polymerization
of ethylene by the producer of peroxides, Akzo Nobel
However, even for this group of reagents the opera-
tion parameters and conditions providing the most
efficient use of peroxide, taking into account the
specific consumption and quality (amount of extract-
able impurities) and assortment of the products,
should be tested experimentally. This especially
concerns the use of peroxide mixtures in autoclave
reactors and mixtures of peroxides and oxygen in
The data on the optimal use of peroxides in one-
and two-zone industrial reactors of autoclave type
(ideal mixing reactors) with production capacity from
16 to 20 thousand tons per year are given below.
Initiator performance. In our work we tested nine
peroxy initiators; data on their initiation power are
listed in Table 1.
As seen, the specific consumption of initiators de-
creases on passing from low-temperature (Tr-36) to
high-temperature (Tr-B) peroxides. Only two per-
oxides do not obey the general trend toward a de-
crease in the specific consumption with increasing
temperature: Tr-D initiator with very high perfor-
mance in the corresponding temperature range and
Tr-C initiator with increased specific consumption,
which is due to its use in industrial reactors at tem-
peratures higher then the optimum to provide the proc-
ess stability. With increasing temperature of the reac-
tion mixture, the generation of heat decreases and the
temperature in the reaction zone begins to decrease,
i.e., the process passes to the self-control mode.
Specifically this operation mode is used with Tr-C