Abstract :
[en] The increase of greenhouse gases (GHGs) concentration in the atmosphere, mainly emitted by human activities, is making our planet warmer which causes climate change and significantly impacts life on Earth. Carbon dioxide (CO2) is the most abundant anthropogenic GHG. Consequently, intensive efforts are underway to reduce CO2 emissions from the industrial sector. In this context, Carbon Capture Utilization and Storage (CCUS) process chain is an important CO2 mitigation option to be implemented. Using CO2 as feedstock offers a wide range of solutions to produce added-value chemicals [1] while reducing the dependency on fossil resources. One of the most CO2-based alternatives that appears to be viable at high levels of maturity as well as suitable for implementation in the near future at a significant scale is the methanol [2]. Many studies have addressed the catalytic hydrogenation of CO2 to methanol and a variety of heterogeneous catalysts associated to this reaction has been proposed in the literature. Metal-based catalysts, in particular the copper-based ones are the main systems used for the named reaction thanks to their high activity and low cost [3].
Various studies investigated the copper-based catalysts, their different synthesis methods and the combination of copper with other metals and/or oxides in order to enhance the performances at laboratory scale [4], [5], but no study has addressed the scaling-up of synthesis and catalytic tests installation and their effects on the catalyst properties and activity. In this context, the aim of this study was to carry out a multi-scale study of a homemade copper-based catalyst (CuO/ZnO/ZrO2), developed using zinc oxide as promoter and zirconia as support. The catalyst has been synthetized by co-precipitation on laboratory scale (4 g of catalyst) and on a larger scale (120 g of catalyst). The catalyst powders were then characterized and tested in a micro-reactor. In a second time, the catalyst powder (produced at large scale) has been shaped by extrusion method, characterized, and tested in micro-pilot reactor to evaluate the catalytic activity at larger scale. Different characterization methods have been considered: X-ray fluorescence, X-ray diffraction, temperature programmed reduction…etc. The catalytic activity tests have been realized between 240 to 300°C under 50 bar considering the same Weight Hourly Space Velocity (WHSV). The characterization results showed that the synthesis scale has no effect on the specific area and crystallite size. The catalyst shaping affects the specific area with total loss of 14 % but no effect was observed on the crystallite size. The catalyst synthetized on large scale presents a methanol productivity slightly higher than that produced at small scale and measured in micro-reactor while the catalytic activity is lower for the shaped catalyst tested in a micro-pilot reactor.
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