Glycerol steam reforming (GSR) has two main advantages: o. Every mole of ..... Traces: Propylene glycol; 2-Cyclopenten-1-one; 2-Cyclopenten-1-one, 2- methyl ...
Hydrogen production via the glycerol steam reforming reaction over Ni catalyst supported on CaO-MgO-Al2O3 Charisiou N.D.1, Papageridis K.N.1, Baker M.A.2, Hinder S.J.2 , Tzounis L.3, Polychronopoulou K.4, Cabeza V.5, Goula M.A.1,*
1Laboratory of
Alternative Fuels and Environmental Catalysis, Department of Environmental Engineering, Western Macedonia University of Applied Sciences, GR - 50100, Koila, Kozani, GREECE 2The
Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 4DL, UK 3Composite
and Smart Materials Laboratory (CSML), Department of Materials Science & Engineering, University of Ioannina, GR-45110, Ioannina, GREECE 4Department 5Department
of Mechanical Engineering, Khalifa University, Abu Dhabi, P.O. Box 127788, UAE
of Chemical and Environmental Engineering & Institute of Nanoscience of Aragon (INA), University of Zaragoza, SP-50018, Zaragoza, SPAIN
Aim of the work
Investigate the catalytic performance and stability of a Ni catalyst supported on CaO-MgO-Al2O3 and compare it with the performance of a Ni catalyst supported on pure alumina for the Glycerol Steam Reforming reaction (GSR) in terms of: i.
Glycerol total conversion,
ii.
Glycerol conversion to gaseous products,
iii. Hydrogen selectivity and iv. Selectivity of v.
Contents
Introduction
Experimental ◦ Catalyst preparation ◦ Catalyst characterization
yield,
◦ Experimental set up & Reaction metrics
gaseous products, and
Selectivity of liquid products.
◦ Characterization of fresh catalysts
Quantitative results (rather than qualitative) of the liquid products are reported. First tine that CaO + MgO have been used as support in the GSR
Results and Discussion ◦ Catalytic performance ◦ Catalytic stability ◦ Characterization of spent catalysts
Conclusions
Introduction
Introduction (1/4) • Biodiesel is produced mainly through the transesterification of vegetable oils and/or fats with alcohols.
• Biodiesel production: A small fraction (0)).
The Ni/modAl catalyst is significantly more active than the Ni/Al one, especially for the lower reaction temperatures (400-650 oC).
Importantly, the modAl support produces more gaseous products than the Ni/Al catalyst; in fact at higher reaction temperatures (over 600 oC) the performance of the modAl is comparable to the Ni/modAl catalyst.
Figure 7: Total glycerol conversion and glycerol conversion into gaseous products for all samples [Reaction conditions: Liquid stream: C3H8Ο3 (20% v/v) and H2O (total liquid flow rate = 0.12 ml/min), Gas stream: He (Q=38 ml/min)]
Catalytic performance (2/4) Gaseous Products’ Selectivity (a) Ni/modAl: H2 selectivity and yield
Values reach the thermodynamically predicted ones (T>600oC).
Enhanced production of H2 for the whole temperature range can be observed (improved performance also of the modAl support compared with the pure alumina).
The surface properties of Ni/Al2O3 catalyst were modified by adding CaO-MgO causing an increase of steam-carbon reactions and neutralizing the acidity of the support suppressing cracking and polymerization reactions.
CO2 and CO selectivity
Ni/modAl sample is more selective towards CO2 and less selective towards CO for the whole temperature range.
The opposite is true for the Ni/Al catalyst and the supporting materials, i.e. they are more selective towards CO and less selective towards CO2.
Thus, the catalyst ability to transform OHCs into H2 and CO2 was higher for the Ni/modAl catalyst mainly due to the enhanced basicity of the Ni/modAl catalyst (CO2-TPD results) introduced by the addition of CaO-MgO modifiers to the alumina support. Figure 8: H2 selectivity and H2 yield, (b) CO2 and CO selectivity [Reaction conditions: Liquid stream: C3H8Ο3 (20% v/v) and H2O (total liquid flow rate = 0.12 ml/min), Gas stream: He (Q=38 ml/min)]
Catalytic performance (3/4) Gaseous Products’ Selectivity (b) CH4 selectivity
For both catalysts the value is negligible for the whole temperature range, whereas for the supports it increases above 550 oC.
For high water to glycerol feed ratios, as in our case, and at high temperatures (>650 oC), the formation of CH should be inhibited, due to the methane steam reforming 4 reaction.
As the decomposition of glycerol to CH4 is highly favorable during the reforming process, both catalysts seem to have sufficient capacity for reforming the produced CH4 into hydrogen and carbon monoxide.
H2/CO and CO/CO2 molar ratio
Ni/modAl: CO/CO2 molar ratio is close to zero for the whole temperature range.
Ni/modAl: H2/CO molar ratio value initially increases with increasing temperature (maximum of 20 at 550oC) and then decreases (value of 8 at 750oC).
Ni/Al: Both ratios are equal to 2-3 and appeared relatively stable for all temperatures.
Supports: the CO/CO2 molar ratio value is negligible, whereas the H2/CO molar ratio decreases from 400 to 500oC, increases from 500 to 650 oC and decreases again for 650oC
