(339c) Techno-Economic Assessment of Cerium Oxide Nanocatalyst Production Via Supercritical Hydrothermal Synthesis

Cerium oxide is an important material for various industrial chemical reactions due to its outstanding physicochemical properties such as high surface area, redox activity, and oxygen storage capacity[1]. Given that the nanoscale particle size of cerium oxide improves its catalytic performance due to its increased surface area, cerium oxide nano-catalysts have also gained significant attention in recent years, especially for their potential in carbon dioxide (CO₂) utilization in applications such as catalyzing the conversion of CO₂ to value-added chemicals such as polycarbonates, methanol, formic acid, etc.

Traditional cerium oxide nanocatalyst synthesis methods include chemical precipitation[2][3], spray pyrolysis[4], and solvothermal method[5]. These methods usually require long reaction times, and the use of hazardous chemicals, resulting in high energy demand and environmental impacts[6]. Supercritical hydrothermal synthesis (SHS) is an emerging method for the sustainable synthesis of cerium oxide nanocatalyst. This method involves the reaction between a cerium salt and water under supercritical conditions, leading to enhanced mass transfer and reaction rates, resulting in the formation of high-quality nanoparticles[7] (Fig.1). Despite the promising results of the supercritical hydrothermal synthesis, there are still challenges that need to be addressed. One of the primary challenges is the scalability of the process. While supercritical hydrothermal synthesis has been demonstrated on a laboratory scale, it is essential to evaluate its feasibility for large-scale production. The techno-economic assessment of the industrial-scale production of cerium oxide nanocatalyst using supercritical hydrothermal synthesis presented in this study addresses this challenge. The results demonstrate the potential of the process for scalability with acceptable values, paving the way for further research and development in this area.

The study was divided into two main parts. First, a preliminary evaluation was conducted to determine the availability and production of the cerium oxide mineral. Second, a mass and energy balance, operating costs, and capital investments were estimated for the scalability of the supercritical hydrothermal synthesis process. The process was divided into four main subsystems: metal salt solution, nanoparticles formation, separation and solvent recovery, and auxiliary subsystems for heating and cooling utilities.

Preliminary results showed that for an industrial production of 42 ton/day of cerium oxide nanocatalyst, the heating consumption would be 3.4 MW/ton, and the minimum selling price would be 3.2 kUSD/ton. Furthermore, a sensitivity analysis was performed on the precursors' concentration to assess their impact on energy consumption. The results demonstrated the potential of supercritical hydrothermal synthesis for scalability with acceptable values in comparison to current market trend of nanomaterials. In conclusion, the sustainable synthesis of cerium oxide nanocatalysts is crucial for the development of environmentally friendly and economically viable industrial chemical reactions, including CO₂ utilization. The findings of this study provide insights into the feasibility of supercritical hydrothermal synthesis for the large-scale production of cerium oxide nanocatalyst, highlighting its potential as a sustainable and cost-effective alternative to traditional synthesis methods.

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