Hydrogen in the synthesis process of graphite

Based on the phase identification of solid products and composition analysis of gaseous products, the chemical interaction between CO2 and LiAlH4 can be described by the following equation: 10LiAlH4+9CO2→7C+6LiAlO2+2Li2CO3+4Al+20H2, where the theoretical molar ratio of LiAlO2 to Li2CO3 is very close to the experimental value of 2.97:1 determined by Rietveld refinement of XRD patterns. The theoretical mass ratio of solid products to reactants is 1.94:1, which is more than the experimental value of 1.84:1. This result is attributed to the evaporation of Al at the temperature of 660 °C, above its melting point. The decreasing Al content is calculated to be 3.3 wt% due to evaporation. To further confirm the chemical reaction (1), the solid products were subjected to TG analysis in the air. The weight change in solid products resulted from the air reaction with carbon and Al, and the decomposition of Li2CO3 is seen in the TG curves. The total weight loss is 10.3 wt%, consistent with the theoretical value of 10.8 wt%, in which 3.3 wt% Al loss and Eq. (1) are used to calculate the theoretical value. The heat released from the chemical reaction (1) is calculated to be 733.6 kJ mol−1 C based on the standard formation enthalpies of reactants and products by the exothermic nature. These results further demonstrate that the chemical interaction between CO2 and LiAlH4 can be expressed by Eq. (1). According to chemical reaction (1), the theoretical yield of graphite based on LiAlH4 is calculated to be 22.1 wt%, which corresponds closely to the experimental value of 20.7 wt% determined by the TG measurement of solid products of CO2 reacting with LiAlH4. The yield of graphite is as high as 93.7%. If you are looking for high quality, high purity, and cost-effective graphite or require the latest price, please email contact mis-asia.

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