1070-4272/02/7511-1816$27.00C2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 11, 2002, pp. 1816!1819. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 11,
2002, pp. 1851!1854.
Original Russian Text Copyright + 2002 by Kuznetsova, Dobkina, Nefedova, Lavrishcheva.
Vanadium Catalysts Promoted with Magnesium Compounds
for Production of Sulfuric Acid
S. M. Kuznetsova, E. I. Dobkina, L. A. Nefedova, and S. A. Lavrishcheva
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received March 6, 2002
Abstract-The feasibility and efficiency of promotion with magnesium compounds of supported and mixed
catalysts for sulfuric acid production were studied.
Production of sulfuric acid based on catalytic oxi-
dation of SO
on vanadium catalysts is one of the
most large-tonnage processes in chemical industry.
Efforts to make the production of sulfuric acid more
efficient include development of new and improve-
ment of existing processes and catalysts. The catalysts
in the existing processes operate in a fairly broad
range of temperatures and concentrations. To extend
further this range, new flowsheets are developed, al-
lowing gas conversion at a large concentration of sul-
fur dioxide under pressure. There is no universal
catalyst exhibiting equally high performance under
different reaction conditions . To each range of
temperatures corresponds its own optimal catalyst
Because the state of a catalyst essentially depends
on reaction conditions, it should be expected that there
should be certain optimal catalyst compositions ensur-
ing the highest performance under different condi-
For gas conversion at increased concentrations of
sulfur (more than 10%), it is advisable to perform the
process in a fluidized bed with a wear-resistant finely
dispersed catalyst [2, 3].
In catalytic method of the sulfuric acid production,
heterogeneous vanadium catalysts are used [3, 4].
Vanadium oxides dissolved in disulfates of alkali
metals (promoters) containing more or less SO
active components of all these catalysts [3, 4].
The most widely used promoter in industrial cata-
lysts is readily available and cheap potassium. At the
reaction temperature, the active component of the
catalysts for sulfuric acid production exists as
a molten mixture of the salts over the pore surface of
a silicate support [4, 5].
The catalyst for oxidation of gases with increased
concentration of SO
in a fluidized bed should exhibit
activity in a wide temperature range, including T ~
380oC, and low abradability during operation. The
first condition is met by catalytic masses containing as
promoters, along with alkali metal ions, also mag-
nesium additives [1, 3].
The goal of this study was the development of
promoted catalytic masses intended for production of
sulfuric acid in fluidized and filtering beds.
Because the catalysts in a fluidized bed should
exhibit enhanced resistance, it is advisable to apply
the active component onto appropriate support. The
support should have the necessary strength and chemi-
cal composition, whose combination determines the
catalyst activity and strength.
In various vanadium catalysts for sulfuric acid
production, natural or artificial silicate materials serve
as supports [2, 3, 6], in particular, spherical alumino-
silicates with a low content of Al
In this study, aluminosilicate with a grain size of
0.431.2 mm, containing about 5.5% Al
, was the
catalyst support. This material was subjected to hy-
drothermal treatment at 4503600oC for 6 h in a flui-
dized bed. The humidity of air fed for fluidizing
ranged from 30 to 40%. The temperature was raised
stepwise to 400, 500, 600, and 700oC; the heating
time at each temperature was 2 h.
The heat treatment was done to enhance the water
resistance of a support. As a result, we obtained alu-
minosilicates with the following structural character-
istics: pore volume 0.630.7 cm
at the average
pore radius of 536 nm and specific surface area of