ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 8, pp. 1261−1267. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.Sh. Bikmurzin, A.A. Lamberov, R.G. Romanova,
2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 8, pp. 1139−1145.
Recycling of Molybdenum in Iron-Potassium Catalysts
for Dehydrogenation of Isoamylenes
A. Sh. Bikmurzin
, A. A. Lamberov
, and R. G. Romanova
Nizhnekamskneftekhim PAO, Nizhnekamsk, Tatarstan, 423574 Russia
Kazan (Volga Region) Federal University, ul. Kremlevskaya 18, Kazan, Tatarstan, 420008 Russia
Kazan National Research Technological University, ul. Karla Marksa 72, Kazan, Tatarstan, 420015 Russia
Received July 29, 2015
Abstract—Method is found and substantiated for recovery of molybdenum from a spent iron-potassium catalyst
for dehydrogenation of isoamylenes to isoprene. The effect of various factors (nature and concentration of the
extracting agent, temperature and duration of the extraction process, and ratio between the liquid and solid phases)
on the selectivity of recovery and the yield of molybdenum was studied. It is shown that molybdenum can be
recycled in manufacture of iron-potassium catalysts for dehydrogenation of isoamylenes to isoprene.
Modern petrochemical processes in the present-day
world are mostly based on application of heterogeneous
catalysts of various compositions. It is known that, in the
course of operation, catalysts irretrievably lose activity
and there comes a point of time when their further use
becomes inadvisable. Then there appear the problems of
utilization, neutralization, or further use of spent catalysts.
Being the most elementary method, utilization is laden
with a number of intractable problems, such as the need
for specially prepared disposal sites and inﬂ iction of
an irreparable harm to ecosystems of the environment.
Therefore, secondary use of spent catalysts remains a
rather topical task.
The goal of our study was to develop a technique
for recycling of molybdenum in manufacture of iron-
potassium catalysts for dehydrogenation of isoamylenes.
The iron-potassium catalysts are complex oxide systems
mostly composed of iron oxides with addition of various
activators or promoters and, in particular, molybdenum
and cerium compounds. The catalysts are used in the
stage of dehydrogenation of isoamylenes in manufacture
of isoprene from isopentane by the double-stage scheme,
as well as in the dehydrogenation of ethylbenzene to
styrene [1–3]. The amount of spent catalysts for these
processes, formed only at Nizhnekamskneftekhim OAO,
is 300–360 ton a year.
Spent iron-potassium catalysts for dehydrogenation of
isoamylenes constitute a large-tonnage industrial waste
containing substances exerting a strong toxic inﬂ uence
on the environment. To these can be attribute oxides of
transition metals and, in particular, molybdenum and those
of rare-earth elements (cerium). One of ways to use a spent
catalyst is by its recycling, i.e., the maximum possible
recovery of valuable components into the production of
the starting catalyst. To reach this goal, we examined
the effect of physicochemical and technological factors
on the selectivity and degree of molybdenum recovery
from spent iron-potassium catalysts and analyzed the
possibility of using the resulting molybdenum-containing
catalysts in manufacture of catalysts.
We used in our experiments spent iron-potassium
catalysts worked out on an installation for dehydrogenation
of isoamylenes to isoprene at Nizhnekamskneftekhim
OAO to irreversible loss of catalytic activity. The catalysts
contained (wt %): K
O 12–13, CeO
8–9, CaO 2–3,
MgO 2–3, MoO
1.9–3.7, and Fe
A spent catalyst was ground, sieved to a grain
size not exceeding 0.20 mm, an agitated to provide
homogenization, and then its elemental composition