Green Chemistry and the Biorefinery - The Economic Utilisation of Food Co-Products - page 23

Pyrolysis carried out in a continuous down-flow fixed-bed microreactor can
take place with flow rates of nitrogen from 30-70 mL/min, temperatures of
650-800 1C and at atmospheric pressure. It was shown that the type and size of
packing material in the tubular reactor can affect the conversion of glycerol and
subsequent product distribution. Typical products include carbon monoxide,
hydrogen, carbon dioxide, methane and ethane. At lower temperatures under
steam or supercritical water conditions, longer molecules such as acrolein,
formaldehyde and acetaldehyde are observed.

d n 9 r 3 n g | 1

1.3.9 Biotransformations
Glycerol can be converted to a very large number of chemicals using micro-
organisms and enzymes. The aerobic conversion of glycerol to 3-
hydroxypropionaldehyde (3-HPA) was reported in 1985 by Slininger and
Bothast. 36 The cells of klebsiella pneumonia can be grown on a rich glycerol
medium and production of 3-HPA starts when these micro-organisms are
added to a buffer containing semicarbazide and glycerol. It was shown that a
yield of up to 84% could be obtained, however this yield is sensitive to cell age
and cultivation medium. The optimal processing conditions for this experiment
were 32 1C, pH 7-8 and glycerol concentrations of 20-50 g/L.

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