formaldehyde - Sciencemadness Dot Org

FORM ALDEHYDE PRODUCTION 11
catalyst, gaseous mixtures containing from 0.5 to 0.3 gram oxygen per gram
of methanol give manufacturing yields ranging from 73 to GO per cent and
net yields from S3 to 92 per cent of theoretical. A methanol-air mixture of
the type cited contains 30 to 41 per cent of methanol by volume. With
increasing concentrations of methanol the manufacturing yield gradually
falls off, but the net yield increases. Homer 17 states that net yields of
around 90 per cent are obtained in commercial practice. Catalyst efficiency
is readily determined by analysis of the exit gases as indicated by the figures
in Table 1 1T . From these figures the net yield of formaldehyde can be calculated
in the manner illustrated. It will be apparent that the oxygen of
the incoming air is almost completely consumed and that a high hydrogen
content must be maintained to secure good yields. This means that the
Table 1.
CO,
CO
CH4
Os
ixn
N2 ft
Analysis of Formaldehyde Process Exit Gases.
Data from H. W. Homer
>y differe nee)
1 '
Efficient
Catalyst
OJd or Poisoned
Catalyst
4.8
0.2
0.3
0.3
20,2
74.2
5.5
0.&
0.4
0.3
17,5
75.7
The per cent of theoretical yield can be calculated from the analysis shown for
the efficient catalyst as follows:
or V*M - im - im r %CQ2 + %CO + %CH, "|
'° ~ Lo.52S(%N2) + %Ha+2(%CH