A major challenge presents in the on-board synthesis of hydrogen from fossil fuels. There’s the need of a fuel processor that can effectively convert hydrocarbon fuels into hydrogen for various applications in fuel cells. However, hydrogen-rich gas for fuel cells application can be synthesized by the catalytic conversion of oxy-compounds and hydrocarbons, including propane, acetone, methanol, and dimethyl ether.
Among these potential compounds, catalytic conversion of dimethyl ether and methanol comes with effective performance and superior selectivity at low temperature. Methanol steam reforming is a potential approach for the on-board hydrogen production, and luckily, dimethyl ether steam reforming can be applied for the same purpose. Dimethyl ether steam reforming comes with lots of benefits including high heating value, superior self-ignition, and its environmentally friendly.
Collaborative research between scientists at Institute of Physical Chemistry Polish Academy of Sciences and University of Málaga in Spain studied the catalysts of vanadium and nickel in the dimethyl ether steam transforming. Their main goal for the study was to investigate hydrogen production and the varying processes undertaken in the steam reforming of dimethyl ether, while considering a second process involving methanol steam reforming. Their work is published in peer-reviewed journal, International Journal of Hydrogen Energy.
The authors prepared Vanadium-nickel catalysts through a multistage impregnation of nickel and vanadium compound making use of an alumina support. By varying vanadium content in the proposed samples, the authors were able to come up with three distinct samples. Ring and powder form specimens were tested.
The authors observed that in the methanol steam reforming at 350°C, nearly complete methanol conversion was achieved irrespective of vanadium concentration. For non-catalytic analysis using quartz particles with the same size and weight as catalysts applied in the catalytic tests, the authors didn’t observe any activity at 400° C. They realized that carbon monoxide and hydrogen were the main products without using a catalyst.
However, carbon monoxide and hydrogen were the initial products the authors collected when they fed a mixture of water and hydrogen over vanadium and nickel catalysts. Carbon dioxide appeared when the temperature was raised from 250°C to above 300°C. These outcomes indicated that methanol decomposition was the preliminary step when vanadium and nickel are used as catalysts.
The authors evaluated the activity of dimethyl ether without steam over vanadium-nickel catalysts. They recorded no conversion below 250°C. When they use 0.5% Vanadium-nickel catalysts, the conversion increased linearly with temperature reaching 100% at 350°C. At this point, methane and carbon dioxide were the principle products with low amounts carbon monoxide. Two main reactions marked the completion of dimethyl ether conversion at 500°C. Hydrolysis of dimethyl ether and methanol steam reforming, which yielded hydrogen-rich gas reformate produced with hydrogen selectivity c.a. 60-70%.
Rafael Gonzalez-Gil1,2, Concepcion Herrera2, Maria Angeles Larrubia2, Pawel Kowalik3, Izabela S. Pieta1, and Luis J. Alemany2. Hydrogen production by steam reforming of DME over Ni-based catalysts modified with vanadium. International journal of hydrogen energy, volume 41 (2016), pages 19781-19788.Show Affiliations
- Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warsaw, Poland.
- Departamento de Ingeniería Química, Facultad de Ciencias, Universidad de Málaga, E-29071 Malaga, Spain.
- New Chemical Syntheses Institute, 24-110 Pulawy, Poland.
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