Steam reforming (SR) of n-butanol and its main reaction intermediates, i.e., 1-butene, and butyraldehyde, was studied over 0,5wt.% Rh/ZrO2 catalyst at 500 and 700°C, atmospheric pressure and steam to carbon (S/C) molar ratio of 4. Coke deposits on the spent catalyst samples were characterized using temperature programmed oxidation (TPO) and CHNS+O elemental analysis. Catalyst performance, i.e., conversion, product distribution and short term stability, as well as coke deposit characterization, were utilized to develop reaction networks for 1-butene, butyraldehyde and butanol. At 500°C the individual reforming rates of the three components decrease in the order butyraldehyde>butanol>1-butene and the initial reaction rates of butanol decrease in the order dehydration>dehydrogenation>direct reforming. The three main pathways, i.e., direct reforming of butanol and reforming via butane and butyraldehyde respectively, contributed roughly equally to the butanol reforming activity of the catalyst at 500°C. At 700°C, complete conversion was observed for all components, with hydrogen yields 70% of theoretical maximum for butanol and 1-butene and 60% for butyraldehyde. Deactivation of the catalyst for reforming is caused by carbon deposition on and near the Rh particles. The deposition is a side reaction of the reforming surface reaction and decreases in the order of magnitude butyraldehyde>butanol≧1-butene. Carbon deposition elsewhere on the support proceeds mainly via the coupling products of butyraldehyde.
- Butanol steam reforming
- Catalyst deactivation
- Reaction pathway
- Temperature programmed oxidation