Co-precipitation of CuZn(Al) precursor materials is the traditional way of synthesizing Cu/ZnO/(Al2O3) catalysts for industrial methanol synthesis. This process has been investigated by titration experiments of nitrate and formate solutions. It was found that the solidification of the single components proceeds sequentially in case of nitrates: Cu 2+ is precipitated at pH 3 and Zn 2+ (as well as Al 3+ ) near pH 5. This behavior prevents a homogeneous distribution of all metal species in the initial precipitate upon gradual increase of pH and requires application of the constant pH micro-droplet method. This effect is less pronounced if formate instead of nitrate is used as counter ion. This can be explained by the strong modification of the hydrolysis chemistry of the metal ions due to the presence of formate anions, which act as ligands and buffer. A formate-derived Cu/ZnO/Al2O3 catalyst was more active in methanol synthesis compared to a nitrate-derived sample although the same crystallographic phases were present in the precursor after co-precipitation and ageing. The effect of precipitation temperature was studied for the binary CuZn nitrate model system. Increasing the temperature of co-precipitation above 50 °C leads to down-shift of the precipitation pH of Zn 2+ by a full unit. Thus, in warm solutions more acidic conditions can be used for complete co-precipitation, while in cold solutions, some Zn 2+ may remain dissolved in the mother liquor at the same precipitation pH. The higher limit of temperature is given by the tendency of the initial Cu precipitate towards formation of CuO by oxolation. On the basis of these considerations, the empirically determined optimal pH and temperature conditions of the industrially applied synthesis can be rationalized.

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Magnesium air fuel cell (MAFC) systems are eco-friendly fuel cells that use electrolytes of saltwater and oxygen from the air to produce power. However, MAFC cells face a critical problem, which is the deposition of side products on the surface of the Mg anode plate and the cathode electrode. Therefore, this study will focus on the analysis of factor on Mg(OH)2 deposition by identifying the optimal seawater, Mg alloy, and surface roughness and additives solution. Magnesium plates AZ31 are used as the anode, and air electrode as the cathode. This study also considers physical characteristics such as SEM, EDX and corrosion test while chemical characterization by performance test with difference electrolyte, anode, and roughness. Catechol-3,5-disulfonic acid disodium salt (tiron) as anti-deposition used to reduce the deposition of Mg(OH)2 on the anode and cathode surfaces and thus improve the performance of MAFC. From the performance study, the MAFC able to produce a power density of 27.54 mW/cm2 which is high compare to the MAFC without tiron. Therefore, with the active area by 110.25 cm2, the MAFC generates 2.93 W. The deposition of Mg(OH)2 reduces the active area of magnesium oxidation, thus, reduce the electricity generation. With the knowledge of optimal seawater concentration and improvement of a single fuel cell system, this study is expecting to assist the fisheries and aquaculture sector as well as the coastal communities in terms of providing a better, safer, and cheaper alternative source of electricity.

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