Molybdenum anchoring effect in Fe–Mo/MgO catalyst for multiwalled carbon nanotube synthesis

Abstract

Two Fe-based monometallic and four bimetallic catalysts based on Fe–Co and Fe–Mo, supported on commercial Al2O3 and MgO, were tested in carbon nanotube (CNT) synthesis by catalytic ethylene pyrolysis. The focus was to evaluate the influence of Mo addition to Fe, together with the particular role of support. Transmision electron microscopy revealed a synergetic effect of Mo and MgO: optimal metal-support interaction (MSI) resulted in small, well-defined and highly distributed Fe–Mo nanoparticles, enabling the best pyrolytic performance. It can be portrayed as the highest CNT yield presented per catalyst specific surface area, as well as the thinnest CNTs with the narrowest diameter distribution. Raman and X-ray diffraction examination of the CNTs obtained on the same catalyst revealed their highest quality in terms of lattice defects, as well as the degree of crystallinity.