II International Symposium on Carbon for Catalysis ABSTRACTS

PP-<strong>II</strong>-18
Thus, the object of this research was to develop new effective catalysts, based of carbon
material sibunit for acetaldehyde synthesis by ethanol dehydrogenation.
Our previous researches have shown that based on sibunit copper-containing catalysts are
the most effective for acetaldehyde synthesis. The maximum yield of acetaldehyde reached
69,2% at 375 0 C at the presence of catalyst 3%Cu/sibunit. However such systems were
unstable in the process conditions. Activity of this catalyst sharply decreased at high
temperatures (above 400 0 C). One of the ways of increase of catalysts stability is introduction
of promotional additives, which interfere of copper sintering. In this connection we
investigated expediency of introduction of Cr 2 O 3 additives in copper containing catalysts.
Our studies have shown, that chrome oxide possesses of catalytic activity in ethanol
transformation. Conversion of ethanol was 58% at 500 0 C at the presence of catalyst
3%Cr 2 O 3 /sibunit and the main products were acetaldehyde and ethylene. Thus, the received
results have allowed to assume, that the additive of small amounts of Cr 2 O 3 can increase
activity of the catalyst. For acknowledgement of this assumption we have tested the samples
of copper catalysts which contain Cr 2 O 3 additives in different quantities.
100
80
60
40
20
0
Cu
Cu-Cr2O3
100
80
60
40
20
0
350 375 400 425 450 500
350 375 400 425 450 500
Fig. 1. Ethanol conversion (%) Fig. 2. Yield of acetaldehyde (%)
The best results were obtained in the presence of catalyst, containing copper and chrome
oxide in the ratio 20:1. Introduction of Cr 2 O 3 in the catalyst has allowed to raise considerably
activity of system in the area of temperatures above 400 0 C. Alcohol conversion was almost
twice above, than at the presence of unpromoted catalyst (Fig. 1). However, selectivity of the
process is a little below, that is caused by an intensification of ethylene and 1,3-butadien
formation. The maximal yield of acetaldehyde, received at the presence of the catalyst 3%Cu
0,15%Cr 2 O 3 /sibunit, was 63,3 % at 375 0 C (Fig 2.).
Besides introduction of the chrome oxide additive has allowed to increase duration of
stable work of the catalyst considerably. In the process conditions which provide the maximal
yield of acetaldehyde, based on sibunit catalyst, containing 3%Cu and 0,15%Cr 2 O 3 can work
stably not less than 80 hours. While the activity of the system, containing only 3%Cu without
any additives, decreased in 30 hours.
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