Thermodynamic Analysis of Hydrogen Production from Oxidative Steam Reforming of Ethanol

Abstract

A thermodynamic analysis of ethanol oxidative steam reforming was carried out with a Gibbs free energy minimization method. The addition of oxygen lowers the enthalpy of the system and favors the heat recycle. Thermal-neutral (TN) conditions are obtained, at which the heat released from exothermic reactions makes up exactly for the requirement of the endothermic reactions. At three temperatures, 700, 900, and 1100 K, the ratios of H 2 O/EtOH and O 2 /EtOH for making up TN conditions are estimated, and the equilibrium moles of hydrogen, methane, carbon monoxide, and carbon are examined. 900 K is favorable for hydrogen production where the maximum equilibrium mole of hydrogen appears, with coke and methane being suppressed effectively. For the non-TN operations, a detailed calculation is presented on a range of reaction conditions, i.e., temperature of 700-1100 K and H 2 O/EtOH and O 2 /EtOH feed ratios in 1.0-10.0 and 0.0-0.9, respectively. Hydrogen is favored at low O 2 /EtOH ratio, high H 2 O/EtOH ratio, and 900 K. Methane is not favored at high temperatures and high O 2 /EtOH and H 2 O/EtOH ratios. Carbon monoxide increases with the increase of temperature. Carbon formation can be avoided by adjusting the reaction condition in a reasonable range.

Thermodynamic Analysis of Autothermal Reforming of Synthetic Crude Glycerol (SCG) for Hydrogen Production

“…Figure 1 shows the mole fraction and molar flow rate (kmol/h) versus temperature profile at various synthetic crude glycerol concentrations. As noted, the mole fraction and molar flow rate of H 2 increases with increasing operating temperature due to the endothermic nature of the reforming reactions which are favoured at higher temperature in agreement with similar studies [17,18]. However, a plateau was reached and the change in hydrogen production was insignificant after a temperature of about 973 K. The result also shows that the amount of hydrogen obtained with pure glycerol (G) is higher in comparison with glycerol plus methanol (GM) due to the higher stoichiometric hydrogen content of glycerol as compared to methanol (7 moles as compared to 3 at equilibrium conditions).…”

Advances in Ethanol Reforming for the Production of Hydrogen

“…[50][51][52] In general, the selectivity for H 2 is 60%-70%, which is close to that predicted by thermodynamic analysis (~70%) and depends on the reaction conditions. Table 1 lists the reaction conditions that were used to evaluate the activity of catalysts for reforming along with the observed ethanol conversion and selectivity for hydrogen.…”

Hydrogen production from oxidative steam reforming of ethanol over rhodium catalysts supported on Ce–La solid solution

“…(15) can be considered as the combination of Eqs. (14) and (16). This means that the CO WGS reaction plays an important role in the CH 3 COCH 3 removal reaction.…”

“…CH 3 CHO and CH 3 COCH 3 , CH 2 CH 2 ) decrease [4,16]. The distributions of the above products, together with ethanol conversion, depend not only on the reaction conditions chosen but also on the selection of catalyst [4,5].…”