THE CATALYTIC ACTION OF AI*** IONS IN REDUCTION-OXIDATION SYSTEMS
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CIA-RDP78-04861A000400030015-0
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K
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December 20, 2016
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June 6, 2006
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15
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Publication Date:
August 1, 1955
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REPORT
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THE CATALYTIC ACTION OF Al+++ IONS IN
REDUCTION-OXIDATION SYSTEMS
Roczniki Chemii 20 (1954) 3-11
(From Polish).
August 1955
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THE CATALYTIC ACTION OF AI*++ IONS IN
REDUCTION-OXIDATION SYSTEMS
Roczniki Chemil ,D (1954) 3--11.
(From Polish)
Al... ions are practically inactive in the reaction of the decomposition of H202 and
in the reaction of the peroxidative oxidation of various organic substrates. In conjunction
with other micro-elements and suitable carrier substances, however, the activity of the
Al +++ ions ray be strong and the specific action of this element is then important.
-----------------
The advantageous influence or Al... as catalytic agent of certain organic reactions
has long been known. The Friedel and Krafts reactions, inter alla, are good examples of
this. As is well known, the course of these reactions depends upon the presence of AlCl3.
With regard to blo-catalytic systems, the action of Al+++ ions was investigated first
of all by plant physiologists and soil experts [i]*. According to the opinion of the experts,
Al... ions even In very low concentrations, exert on the whole a harmful Influence on the
growth of many plants, especially in an acid environment. It appears, however, that there
are exceptions to this rule, as Is shown by the investigations of Znamienski [2] who originally
observed the advantageous action of the element by accident in a variety of wheat (Triticum
pseudohostianum).
In'the reduction-oxidation systems investigated in recent years in this Institute [3],
the Al''. +ion behaves fundamentally in an inert manner. It does not decompose H202 or intervene
in reactions for the removal of oxygen on oxidised substrates. Nevertheless, the fact does not
justify the assertion that Al+++ ions are altogether deprived of any influence on catalytic
actions of this type. In the article 10n the sociology of chemical elements" [3,4], we have
endeavoured to explain that it is Impossible to predict the catalytic properties of any element
or ion, as long as we do not know its position In the group of other elements, in the sphere of
which the said element, as a catalytic agent, may have an entirely different form from that
which It has as a separate. individual. It had therefore to be assumed that in association
with complex catalysts,. the Al+++ ion would be able to act as an Inhibiting agent or as promoter,
according to the prevailing experimental conditions in relation to a given catalytic reaction
taking place-with a suitable substrate. In fact, in the course of our investigations on
catalysis and catalysts, we found characteristic examples of complex catalysts exhibiting the
two-fold behaviour of Al... ions in reduction-oxidatioh systems. The results of these
investigations are given in the following account.
I. Al +++ IONS AS INHIBITING AGENT.
When investigating the various systems of complex catalysts we had the opportunity of
repeatedly confirming the fact that Al+++ ions in many cases exercise an inhibiting action In
the decomposition or H202 at a temperature of 37?. As catalyst supporters or carriers for
the Al +++ ions, we used the following complex gels. which were prepared by careful mixing and
air drying.
Mixed gel of aluminium, chromium and iron hydroxides precipitated at a temperature of
200 by addition of a small amount of ammonia to an;-aqueous solution containing AiC13 +
CrC13 + Fe(No3)3 In the atomic proportions Al: Cr: Fe - 1:1:1. The water content of
the air-dried gel was 44.4% H20.
For references, see end.
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(2) Mixed gel'of copper + lead'+ iron hydroxides of a light-brown colour, precipitated at a
temperature of 200 by sodium hydroxide (free from 002) In stoichiometric proportions from
a mixed aqueous solution of Cu(NO3) 2 + Pb(NO3) 2 + Fe(NO3)., in the atomic proportions
Cu; Pb: Fe = 1:1:1. The air-dried gel contained about 21.8% H20.
(3) Mixed gel of magnesium + copper +. iron hydrox1pas ghtain$d b, precipitation from an aqueous
% solution of M3C12 + CuSO4 + FeCl3 (atomic propott~ions Mg: Vii: Fe = 0.3:0.3:1) by adding
NaOH in small amounts at a temperature of 20?. The air-dried gel contained about 38.5
H20.
(4) Gel of cobalt ferrocyanide prepared at.a.tempe,rature.of 209 from an.aqueous solution of
Na4[Fe(CN)63 + Cu(N03)2 in stoichiometric proportions, NH4C1 being used as coagulant.
The air-dried preparation contained about "Y2 o~H20.
All the preparations i to 4 decomposed H20? vigourously at a temperature of 37?. The
Al 103 adsorbed on the surface of these catalysts was a paralysing. agent in all the experiments,
sometimes very active. In an experiment of a mixed catalyst (5 mg) of copper, magnesium and iron
hydroxides, the a,ctivity,of the Al+++, ions was still perceptible in a density of 106 gain 201 ml
of H.O. solution, 1.e..,in:a dilution of 1:200 millions.: The results of these experiments are
shown In Tables 1, 2 and 3:`
In the course of these Investigations, we also found simple catalysts exhibiting
susceptibility to the. poisoning action of Al+++ Ions. A6cording,to Wolski's investigations [5],
the catalytic activity of copper, oxide (.10 mg) undergoes a considerable diminution in the presence
of 1 mg of Al+++ The air-dried copper oxide contained 4.3% H2O and was obtained In the wet
method by preparing a gel of Cu(OH)2 in an alkaline solution (i n NaOH). The results obtained are
shown In Table 4.
II. Al+++ ION AS PROMOTER
In passing to the action of Al+?; ions as an activating agent, it must be stated that in
general this element is found less frequently in the role. of promoter than as a inhibitor. When
investigating the efficiency of different catalysts and carriers in reduction-oxidation systems
in the presence of certain substrates, we found that copper oxide, of which we have already spoken
is activated, by_Al+++, when it 1s a matter of the oxidation of indigo-carmine by means of HO2
(Table 4).
Nevertheless, the Al... may likewise be an activator in the reaction of the catalytic
decomposition of H.O. A good example of this is the complex catalyst of a gel of copper-iron
ferrocyanide, investigated recently [6]. The efficiency of this catalyst is increased considerably
under the influence of Alm+, as is shown by the. figures given in Table 5. We have investia'ted
the so-called catalytic mutation [7], the influence of which is sufficiently clearly marked. The
order, in which the separate components of the catalyst are added during its preparation is not
immaterial. The most advantageous combination, as follows from Table 5, is the following order:
CU+++ + fio,+++ + [1'e(CN)8]-4 + AZ+++
[FjR(CN) j-4 + Cu++ + pp+++ + Al...
The above figures snow: that the Al+ acted in these systems as an efficient activator,
especially in relatively high concentrations (102 4 'and 10-3 g Al+~). This action disappeared
on reducing the concentration to 10-5 g Al... in 200 ml of H2O2.
If the complex catalyst investigated is used in the system HO00H/H202, there occurs an
intense acceleration of the oxidation reaction of the formic acid at a temperature of'37?, as
shown by our previous investigations [S]. ' The addition of Al +.++ ions was not without influence
in this. case also, since it produced - i.t a s,true in different degrees - a slight inhibition of
the oxidation reaction of formic acid, depending on the mutation employed (see above) On
comparing the figures given in Tables 5 and 6, one is struck above all by the fact that the
strongest inhibiting action of the Al... ion in the peroxidative reaction is found in the
combination of the catalyst (Ca ++ + Fe+ + [Fe(ON)6]-4 in connection with which the Al' ++Ion
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Cum-0 - - Al 0
-O-Al = 0
was the most efficient catalytic promoter in the reaction of the decomposition of H202
(Table 5). Generally speaking, the position is similar to that obtaining in the case of the
catalyst Cu/A1+++, although in the converse relation, since in these Conditions, the A1' ion
was distinguished as a peroxidative activator, being simultaneously a catalytic inhibitor.
The catalytic action of Al+++ ions in reduction-oxidation systems is thus twofold
and to a high degree specific. Since a similar phenomenon-although not in such a striking
form - has been considered by us in the, case of other ions (for "example Co+++) [S], the
conjectur-, arises that a certain rule is involved here, from which there may also be exceptions.
Recently, Winowski [9], when investigating CdO as a carrier, found that the Al+++'ion also
produced a diminution in the decomposition of H2