The development of renewable and alternative fuels such as biodiesel is becoming increasingly important because of the depletion of fossil fuels and global warming. Biodiesel is currently produced by transesterification of triglycerides and methanol, in which crude glycerol is produced as a main byproduct. In our previous work a high acrolein yield was obtained from dehydration of purified glycerol over 12-Tungstophosphoric acid H3PW12O40 (HPW) supported on Cs-modified SBA-15. However, glycerol purification to remove the impurities is very costly. Therefore the present work explores the feasibility of using crude glycerol as feedback for acrolein production by dehydration reactions. The influence of the organic and inorganic impurities in crude glycerol was investigated. Among the impurities commonly contained in crude glycerol, only the alkli metal ions impurities caused catalyst deactivation and decrease in acrolein selectivity. The reason was that alkli metal ions deposited on catalyst surface to form alkaline salts of 12-phosphotungstic acid by neutrilization and decreased the effective medium Brønsted acid sites. This problem was solved by glycerol desalination and a stable acrolein yield of 85% was obtained acrolein in 60 h of reaction, which was as good as the results with purified glycerol. In addition, the catalyst showed a good thermal stability after the reaction with crude glycerol. The activity and selectivity were well maintained after regeneration at the coke burning temperature of 500 oC, as shown in Fig. 1.

Conversion of biodiesel-derived crude glycerol into acrolein

249th National Meeting (2015)

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