Abstract
In this work, the modification of Ni/SBA-16 oxygen carrier (OC) with yttrium promoter is investigated. The yttrium promoted Ni-based oxygen carrier was synthesized via co-impregnation method and applied in chemical looping steam methane reforming (CL-SMR) process, which is used for the production of clean energy carrier. The reaction temperature (500–750 °C), Y loading (2.5–7.4 wt. %), steam/carbon molar ratio (1–5), Ni loading (10–30 wt. %) and life time of OCs over 16 cycles at 650 °C were studied to investigate and optimize the structure of OC and process temperature with maximizing average methane conversion and hydrogen production yield. The synthesized OCs were characterized by multiples techniques. The results of X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) of reacted OCs showed that the presence of Y particles on the surface of OCs reduces the coke formation. The smaller NiO species were found for the yttrium promoted OC and therefore the distribution of Ni particles was improved. The reduction-oxidation (redox) results revealed that 25Ni-2.5Y/SBA-16 OC has the highest catalytic activity of about 99.83% average CH4 conversion and 85.34% H2 production yield at reduction temperature of 650 °C with the steam to carbon molar ratio of 2.
Highlights
Fast depletion of conventional fossil fuel sources and increasing concerns over the global warming phenomenon due to the emissions of greenhouse gases especially carbon dioxide, initiated various researchers for the production of clean energies [1,2,3,4,5,6]
The reduction-oxidation results revealed that 25Ni-2.5Y/Santa Barbara Amorphous 16 (SBA-16) oxygen carrier (OC) has the highest catalytic activity of about 99.83% average CH4 conversion and 85.34% H2 production yield at reduction temperature of 650 ◦ C with the steam to carbon molar ratio of 2
The results showed that the size of NiO crystallite of 25Ni-2.5Y/SBA-16 oxygen carrier is smaller than that of 25Ni/SBA-16 (Table 1)
Summary
Fast depletion of conventional fossil fuel sources and increasing concerns over the global warming phenomenon due to the emissions of greenhouse gases especially carbon dioxide, initiated various researchers for the production of clean energies [1,2,3,4,5,6]. Chemical looping steam methane reforming (CL-SMR) process was proposed in order to overcome these drawbacks [20,21]. In this process the necessity of the gas separation is eliminated since the produced gas is not diluted with N2 [22,23]. Methane is partially oxidized to syngas (H2 and CO) in the fuel reactor, while the metal oxide (Mex Oy ) used as an oxygen
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