Title : Study and optimization of a new synthesis route of metallic catalysts with the use of surfactants for the CO2 hydrogenation to methane
The fast human development has significative contribution to the increase of greenhouse gas (GHG) emissions to the atmosphere mainly due to the use of fossil fuels. Carbon dioxide (CO2) is one of the main GHG that are related to several environmental impacts. Hence, the capture and upgrading of CO2 via different techniques is crucial to the industrial development and to avoid impacts that are related to the greenhouse effect. CO2 hydrogenation is one of the main CO2 conversion processes currently investigated and that has recently reached industrial scale. In this process, a catalytic reaction is performed using CO2 and hydrogen (H2) to produce other energy carriers, such as methane (CH4), methanol (CH3OH), diesel, etc. Catalysts present a crucial role to enable the CO2 hydrogenation. One of the mostly studied ones is the Ni/Al2O3 catalyst, which is commonly synthesized by impregnation techniques, such as the dry, wet, or incipient wetness impregnations. However, this catalyst presents some drawbacks related to its morphology and structure, mainly in terms of the metal-support contact, the metal dispersion over the support, and the particle size of the metal particles. All these parameters can be optimized to improve its performance. This work proposes a new and greener synthesis route in which a biosurfactant (sodium palmitate, a component of residual biooils) is used to isolate Ni nanoparticles from its precursor to perform the subsequent impregnation over the Al2O3. For that, dry and wet impregnation methods are compared to evaluate their influence on the CO2 adsorption. In addition, these two ways of synthesis are adapted and compared in terms of controlling the size of the Ni particles using organic compounds, leading to an improved metal dispersion over the support. Then, catalyst is characterized to observe both phases’ behaviors after performing the newly adapted synthesis using the biosurfactant with XRD, XRF, and SEM. Finally, process parameters, such as temperature, GHSV and reaction time, are evaluated. The highest CO2 conversion that is obtained reaches approximately 70 %, while the CH4 selectivity is near 80 %. At the end, it is observed that all synthetized and tested Ni/Al2O3 catalysts are functional to produce a gas with a considerably high concentration of methane, and further investigation is proposed in terms of optimizing their synthesis.
Audience Takeaway Notes:
- Understand new approaches with the use of surfactants, which are not commonly in catalysis, to synthesize a metal-based catalyst with improved catalytic performance in the CO2 hydrogenation to methane reaction.
- Observe how this newly synthesized and efficient catalyst can have significant implications as a potential solution to climate change mitigation, since it uses a surfactant that is commonly one part of residual biooils in its structure and is applied in a process that promotes the CO2 capture and conversion into methane.
- Identify and propose some other ways to optimize the development of the synthesis route, mainly in terms of the experimental parameters that compose the steps to produce it, in terms of a possible scale up in the future to use it for industrial-scale applications.