from first principles PP-I-1

Steam Reforming of Bioethanol over MnFe 2 O 4 SpinelPP-IV-5Dolgykh L.Y., Stolyarchuk I.L., Pyatnitsky Y.I., Strizhak P.E.L.V. Pisarzhevsky Institute of Physical Chemistry NASU, Kiev, Ukraineldolgykh@inphyschem-nas.kiev.uaThe ethanol steam reforming (ESR) is a subject of undimishing interest as promising way ofthe hydrogen production from renewable feedstock:C 2 H 5 OH + 3 H 2 O = 2 CO 2 + 6 H 2 .Recently, it was shown that NiAl 2 O 4 spinel [1] reveals good performance in the ESR process.Here, we report a study of the ethanol steam reforming over MnFe 2 O 4 spinel.The reaction was carried out in a quartz flow reactor at atmospheric pressure, in thetemperature range 300-700 o C, initial reaction mixture 2.7 mol.% C 2 H 5 OH, 50 mol.% H 2 O, N 2(balance).In the investigated conditions, we achieved the hydrogen yield of 5.5-5.7 mole of H 2 per moleof ethanol that is close to theoretical value for the ESR reaction. Moreover, the importantdistinctive peculiarity of catalytic action by MnFe 2 O 4 is absence of CO as reaction product upto 650 o C. These findings evidence that MnFe 2 O 4 is promising catalyst for ethanol steamreforming. It was observed also that MnFe 2 O 4 catalyzes formation of acetone with selectivityup to 55% at middle temperatures.Taking into account the literature as well as our data, we suppose as working hypothesis, thefollowing simplified mechanism of the ESR reaction on MnFe 2 O 4 (some steps arenonelementary):CH 3 CH 2 OH + 2 O* CH 3 CHO + 2 HO*; CH 3 CHO + HO* H 2 + CH 3 COO*;CH 3 COO* CH 3 * + CO 2 ;CH 3 COO* + * CH 3 СO* + O*;CH 3 CO* + * CH 3 * + CO*; CH 3 * + HO* CH 4 + O* + *CH 3 CO* + CH 3 * CH 3 COCH 3 + 2*; CH 3 * + 4 O* CO* + 3 HO* + *;O* + CO* CO 2 + 2*; H 2 O + * O* + H 2 ; 2 HO* 2 O* + H 2 .Active sites of the explored oxide catalyst include apparently ferrum ions which undergoreversible redox transformations Fe 3+ + e Fe 2+ in the course of catalysis.References:[1] H. Muroyama, R. Nakase, T. Matsui, K. Eguchi, Intern. J. Hydrogen Energy. 35 (2010) 1575.289