Developing carbon tolerant Ni/ScCeSZ cells via aqueous tape casting for direct biogas fed solid oxide fuel cells (SOFC)

Solid Oxide Fuel cell (SOFC) is a promising solution to energy independence, greener energy, with high electrical efficiency and theoretically compatible to operate with gaseous carbonaceous fuel. The problem arises when the benchmark materials (Ni/YSZ) performance drop with operation with carbon fuels. Hence, this thesis aims to develop SOFC cell with alternative materials that have high electrochemical performance with dry carbon fuels for intermediate temperature SOFC. This thesis demonstrates the successful manufacturing of the anode supported cells of Ni/YSZ, Ni/ScCeSZ and Sn-Ni/ScCeSZ via reverse aqueous tape casting method. With this method, SOFC half cells with dense thin electrolyte and porous thick anode produced using multi-layered tape casting and single co-sintering stage. Ni/ScCeSZ was chosen as the base anode substrate material due to the 10ScCeSZ’s high conductivity property and better ability to tolerate carbon-based fuels. Despite the long history of Ni/ScCeSZ cell, this thesis shows the first work that compare Ni/YSZ and Ni/ScCeSZ cells for IT-SOFC with hydrogen and dry carbon fuels. Tin (Sn) introduced as dopant in the final stage to further enhanced the performance in dry carbon operation. for Sn-Ni/ScCeSZ cell. To author’s knowledge, this thesis reported the first work on the electrochemical performance in dry biogas. Comparative study of the electrochemical performance in hydrogen and dry biogas reveals that the maximum power density of Ni/YSZ cell instantly dropped by an average of 80.6% when switched from hydrogen to biogas, 0.37 W/cm$^2$ to 0.05W/cm$^2$, respectively. Ni/ScCeSZ showed better performance in both fuels, with maximum power densities of 0.42 W/cm$^2$ in hydrogen and 0.28 W/cm$^2$ biogas (37.5 % drop). Ni/YSZ and Ni/ScCeSZ show significant differences in the ASR value in biogas operation with values of 2.52 Ω.cm$^2$ and 0.72 Ω.cm$^2$ respectively. With Sn-Ni/ScCeSZ, the OCV increased with the fuel swap from 0.99 V to 1.04 V and the performance in biogas lowered only by an average of 8.3% with a maximum power density of 0.314 W/cm$^2$ in biogas. Contradict to the literature, this thesis provides a new insight to the cause of performances drop with the fuel switch which was mainly affected by the reforming ability of Ni/ScCeSZ and Ni/YSZ anode. Small amount of amorphous carbon deposited on the Ni/YSZ anode while higher amount of graphitic carbon found on the Ni/ScCeSZ and Sn-NiScCeSZ anodes. Sn increased the catalytic activity reforming and methane cracking accompanied by increase amount of graphitic carbon on the anode

Effect of Ni/Malaysian dolomite catalyst synthesis technique on deoxygenation reaction activity of waste cooking oil

Local carbonate mineral, Malaysian dolomite has the potential as a deoxygenation catalyst due to its high capacity of CaO–MgO which enhances oxygen compound removal and produces high-quality green fuel with desirable lighter hydrocarbon. In this work, the performance of Ni-doped-calcined Malaysian dolomite (Ni/CMD900) catalyst with different catalyst synthesis techniques (precipitation, impregnation, and co-precipitation) were compared on the deoxygenation of waste cooking oil (WCO) process for green fuel production. The physicochemical properties of the synthesized catalyst were investigated by X-ray diffraction, Brunauer-Emmette-Teller surface area, temperature-programmed desorption of carbon dioxide, X-ray fluorescence, scanning emission microscopy and transmission electron microscopy analysis while the liquid products were analyzed by gas chromatography-mass spectroscopy and Fourier-transform infrared spectroscopy. Evidently from the result of the observation, the preparation technique plays an important role in determining the physicochemical properties of the catalyst for deoxygenation reaction of WCO in which precipitation technique outperformed other methods. Synthesized Ni-Malaysian dolomite-based catalyst, PRE/Ni/CMD900 catalyst was found to be superior in deoxygenation reaction activity as compared to other catalysts with high conversion of WCO (68.0%), high yield of pyrolysis oil (36.4%), and less coke formation (32.0%)

H2-Rich and Tar-Free downstream gasification reaction of EFB by using the Malaysian dolomite as a secondary catalyst

In this study, Malaysian dolomites as secondary catalysts are placed at the downstream of the fluidized-bed gasifier. Three types of Malaysian dolomites with different elemental ratios of CaO-MgO content denoted as P1, P2, and P3 are investigated with EFB gasification reaction at different cracking temperatures (700–900 °C). The performance of the catalysts with a variation of catalyst to biomass weight ratio (C/B) (0.05 to 0.30 w/w) is evaluated. The findings showed that the total gas yield increased by 20%, hydrogen increased by 66%, along with an almost 99% reduction in tar content with P1 catalyst with the following reaction conditions: gasification temperature of 850 °C, equivalence ratio (ER) of 0.25, and cracking temperature of 900 °C. Malaysia dolomite could be a secondary catalyst to provide a better alternative, tar-free hydrogen-rich gas with the possibility of regeneration and re-use