Produção, caracterização e estudo catalítico de nanofibras cerâmicas produzidas por Solution Blow Spinning, aplicadas como catalisadores heterogêneos a base de níquel nos processos de reforma do metano para produção de hidrogênio

Abstract

The production of hydrogen and synthesis gas through catalytic methane reforming processes was carried out using fibrous catalysts prepared by the Solution Blow Spinning technique. Nickel-based catalyst nanofibers were produced with different types of supports, characterized, and compared with their counterparts prepared by conventional synthesis techniques. The influence of the preparation method was studied under methane reforming reaction conditions, and the experimental results

were separated into three chapters, according to the type of support used. The Ni- CeO2 fibrous catalyst produced by SBS showed good catalytic activity and stability of

30 hours in the dry reforming reaction of methane when compared to a conventional catalyst prepared by wet impregnation of the same composition. Characterizations by XRD, SEM, and XPS evidenced that the good performance of the nanofiber catalyst is due to the good metal-support interaction, high thermal stability, and good oxygen mobility associated with the use of CeO2, which prevent the formation of deposits and growth of metal particles. In the second study, Ni/Co-MgAl2O4 bimetallic catalysts prepared by SBS were compared with catalysts of the same composition prepared by thermal decomposition of hydrotalcites synthesized by co-precipitation. The preparation method influenced the performance of the catalysts in both steam reforming and dry methane reforming reactions. The nanofibers presented good surface and reduction properties, and a mixture of oxides with strong interaction that ensured good catalytic performance compared to the other samples, as well as greater resistance to deactivation by deposition of crystalline carbon. Finally, calcium aluminate nanofiber supports were obtained at a lower calcination temperature than supports produced by solid-state reaction. An industrial waste from the shellfish sector was used as a source of CaCO3 for solid-state synthesis, with the aim of adding value to the waste. The supports were wet impregnated to produce nickel-based catalysts for applications in steam reforming of methane. Regardless of the type of support preparation, the catalysts showed methane conversion above 80% and remained stable throughout the 8-hour tests. Thus, based on the results obtained from XRD, SEM, TPR, XPS, N2 adsorption, and thermal analysis characterization tests, the viability of producing ceramic nanofibers prepared by SBS and the positive impact of their use as fibrous catalysts in heterogeneous methane catalysis was verified. When compared to conventional preparation methods under different methane reforming reaction conditions, the nanofibers showed good catalytic activity, high thermal resistance to prevent particle sintering, and little impact of crystalline carbon deposits that could result in catalyst deactivation.