Katalysatorval och beaktanden vid flerstegsomvandling av glukos till glycerol
Sammanfattning: Through hydrogenation of glucose to sorbitol followed by hydrogenolysis of sorbitol to glycerol a pathway to produce bio propane from lignocellulosic material has been confirmed. A wide range of catalyst was tested, in an autoclave batch reactor, to scout the activity of catalysts already proven active, according to previous literature, as well as catalysts not mentioned in literature for the specific reaction. Catalysts well known for both the hydrogenation of glucose and the hydrogenolysis of sorbitol are catalyst including either nickel or ruthenium as the active metal. The most active system was found to be Ni supported on γ-Al2O3 for both the hydrogenation and the hydrogenolysis. For the unknown process step, the hydrogenolysis, the selectivity was considerably high, 44%. This was though found after almost the triple operating time compared to certain literature with still low conversion rates of 36%, which was explained by the mild conditions and the low catalyst to sorbitol ratio 0.5 wt.-%. Other unexpected findings was the negative effect of a basic promoter for most systems and also the regenerating effect of sorbitol when adding hydrogen to the system which introduces further possibilities in research; studying tentatively the effect of hydrocracking derived from the high reactivity, specifically for the acidic catalyst, and if the retro-aldol is a crucial step, only obtained before the adding of hydrogen.
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