Preparation Of 1,2-propanediol From Crude Glycerol Of Biodiesel Byproduct

As a most superior renewable biomass, biodiesel has been increasingly produced recently, coupled with the serious problem of"excessive glycerol". Delicate addressing the glycerol disposal problem plays an important role to the economic viability of biodiesel industry. This paper presented a comprehensive study about the conversion of glycerol into 1,2-propanediol. Two-step art was focused on, involving the preparation and evaluation of catalysts and analysis and optimization of relevant factors.Moreover, trial study was also carried out on the glycerol based biofuel which was taken as a new utilization manner for glycerol. Main work in this paper included several parts as follows:(1) Cu-Ce and Cu-Zn-Al nanocatalysts were prepared via citric acid (CA) assisted sol-gel method. Techniques of TG/DTA, XRD and TEM were employed to characterize the as-prepared catalysts and their precursors. Results showed that as-prepared catalysts were composed of ultrafine metal oxide particles with well crystallinity Evaluated in dehydration of glycerol into acetol via reactive distillation, both Cu-Ce and Cu-Zn-Al catalysts presented decent activity. An overall yield as high as 83.4% was achieved over Cu-Ce (1:1) catalyst with concentration of 0.06g.mL-1, when reactant initial pH value was 8, and reaction temperature was 200℃. An overall yield of 74.8% was obtained over Cu-Zn-Al (1:2:2) catalyst calcined at 500℃for 3h with a concentration of 0.06g.mL-1 ,under the condition of 20g wt90% glycerol solution as reactant and reaction temperature of 200℃.(2) Raney Ni, Pd/C, Cu-Ce, Cu-Cr, Cu-Zn-Al, Co-Cr catalysts were screened for the hydrogenation of acetol into 1,2-propanediol. Results showed that all these catalysts were effective to the reaction. Raney Ni exhibited better activity than others. Parameter study illustrated that relative low temperature and high hydrogen pressure is advantageous to the acetol hydrogenation, while too long reaction time, too high catalyst and acetol concentration easily lead to secondary reaction.(3) Alcohols from glycerol hydrogenolysis were blended with gasoline to be used as glycerol based biofuel and their miscibility and heat value was tested. Results showed that there is possibility to develop glycerol hydrogenolysis product into biofuel. QSPR method was introduced for modelling and predicting the maximum volume that gasoline can dissolve in glycerol alcohol mixture and it did a good job, which implies that QSPR method has the potential to dealing with the problems arising on the way of exploring glycerol based biofuel.