Glycerol steam reforming reactions

Table 2.10 Glycerol conversion and pure hydrogen recovery data for glycerol steam reforming reaction...

Glycerol steam reforming reaction for hydrogen production... 

Overall glycerol steam reforming reaction C3H8O3 + 3H2O 3CO2 + 7H2... 

The glycerol steam reforming reaction is a combination of glycerol cracking (Eq. (24.15)) and the water-gas shift reaction (Eq. (24.3)). 

The choice of the catalyst is of major importance, since it may increase the rate of the ethanol or glycerol steam reforming reaction to tend toward the thermodynamic equilibrium. In addition, it should remain stable during the process and avoid the production of carbon species, responsible for the catalyst deactivation. 

Table 8.1 Glycerol conversion during glycerol steam reforming (GlySR) reaction in conventional reactors (CRs) at various T and by using different catalysts...

As far as glycerol is concerned, the steam reforming reaction is the following ... 

Contrary to what is observed with ethanol, methane cannot be produced directly by glycerol cracking, but is formed by a secondary reaction of CO or CO2 methanation, fevored at low temperature. Glycerol steam reforming is even more complicated than ethanol steam reforming and many other products have been identified during this reaction, such as hydroxyacetone, as the condensable by-product, followed by acetaldehyde and acrolein [6], and some other minor condensable products such as methanol, acetic acid, ethylene glycol and so on. 

Glycerol steam reforming conversion versus reaction temperature. 

In addition, the catalyst appeared very stable under the reaction conditions little carbon was deposited on the spent catalyst. Other supported metals were less active. The activity order, Ru Rh > Ni > Ir > Co > Pt > Pd > Fe, is very comparable to that measured for the steam reforming of methane. Of all the supports tested, Y203 and Zr02 gave the best results for the Ru-catalyzed steam reforming of glycerol. 

The overall reaction of hydrogen production via steam reforming of glycerol is... 

Steam reforming of glycerol for hydrogen production involves complex reactions. As a result, several intermediate by-products are formed and end up in the product stream, affecting the final purity of the hydrogen produced. Furthermore, the yield of hydrogen depends on several process variables, such as the system pressure, temperature and water-to-glycerol feed ratio. 

Cui, Y., Galvita, V., Rihko-Stmckmann, L., Lorenz, H., Sundmacher, K. (2009). Steam reforming of glycerol the experimental activity of Lai.xCcxNiOs catalyst in comparison to the thermodynamic reaction equilibrium. Applied Catalysis B Environmental, 90, 29-37. 

Aqueous phase reforming of glycerol in several studies by Dumesic and co-workers has been reported [270, 275, 277, 282, 289, 292, 294, 319]. The first catalysts that they reported were platinum-based materials which operate at relatively moderate temperatures (220-280 °C) and pressures that prevent steam formation. Catalyst performances are stable for a long period. The gas stream contains low levels of CO, while the major reaction intermediates detected in the liquid phase include ethanol, 1,2-pro-panediol, methanol, 1-propanol, propionic acid, acetone, propionaldehyde and lactic acid. Novel tin-promoted Raney nickel catalysts were subsequently developed. The catalytic performance of these non-precious metal catalysts is comparable to that of more costly platinum-based systems for the production of hydrogen from glycerol. 

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