Parametric study of hydrogen production from ethanol steam reforming in a membrane microreactor

Abstract

-Microreactors are miniaturized chemical reaction systems, which contain reaction channels with characteristic dimensions in the range of 10-500 μm. One possible application for microreactors is the conversion of ethanol to hydrogen used in fuel cells to generate electricity. In this paper a rigorous isothermal, steady-state two-dimensional model was developed to simulate the behavior of a membrane microreactor based on the hydrogen yield from ethanol steam reforming. Furthermore, this membrane microreactor is compared to a membraneless microreactor. A potential advantage of the membrane microreactor is the fact that both ethanol steam reforming and the separation of hydrogen by a permselective membrane occur in one single microdevice. The simulation results for steam reforming yields are in agreement with experimental data found in the literature. The results show that the membrane microreactorpermits a hydrogen yield of up to 0.833 which is more than twice that generated by the membraneless reactor. More than 80% of the generated hydrogen permeates through the membrane and, due to its high selectivity, the membrane microreactor delivers high-purity hydrogen to the fuel cell.

CFD Simulation of Ethanol Steam Reforming System for Hydrogen Production

“…The diffusion coefficients of the components in the mixture, D ij are obtained from the Chapman-Enskog theory [25]:…”

“…The collision diameter is obtained from σ ij = 1/2 σ i + σ j and Ω ij is taken from [26]: (25) In which τ ij = kT/ε ij is the dimensionless temperature, where k is Boltzmann constant and ε ij = √ ε i ε j is the maximum attractive energy between one molecule of i and one molecule of k. The values of σ i and ε i for the substances used in this work are given in Table 2 [27]. The diffusion coefficients as a function of the temperature are shown in Figure 5.…”

Factorial design analysis of parameters for the sorption-enhanced steam reforming of ethanol in a circulating fluidized bed riser using CFD

“…Such as showing that the percentage of H 2 in effluent gas had a deviation of less than 0.5%, as reported by Johnsen et al 33 and a deviation of about 3.5% for SMR and 1% for SESMR, as reported by Chen et al 61 This might prove that both kinetic models were suitable for the future studies of uidization with SESMR using a Ni-based catalyst and dolomite. Several kinetic models of SRE on a Ni-based catalyst were applied by some researchers, [9][10][11][12]15,17 but unfortunately there was no application with uidization. The only kinetics approach for SRE applied on a typical Ni-based catalyst, such as Ni-Al 2 O 3 , 15,17 is described next.…”

“…8,[12][13][14] In addition, the ETD and ACD reactions can be combined in the ethanol decomposition (EDC) reaction, in which EtOH is directly converted to CH 4 , CO, and H 2 , as shown in reaction (3). 15,16 C 2 H 5 OH / CH 4 þ CO þ H 2 DH 298 ¼ þ49:6 kJ mol À1 3Furthermore, steam can react directly with EtOH in another pathway to obtain CH 4 , similar to the EDC reaction. This reaction is called ethanol decomposition with steam (EDC/S), as expressed in reaction (4…”

Experimental and simulation studies of the production of renewable hydrogen through ethanol steam reforming in a large-scale catalytic membrane reactor

“…The kinetic expressions for a Ni-based catalyst proposed by Sun et al [35] and Xu and Froment [36] were utilized in this study and are presented in Table 2. These kinetic parameters were used to simulate ESR in conventional reactors, and the results were compared with experimental results presented in the literature [33,37]. The kinetics showed >99% accuracy in predicting the performance of ESR.…”