Efficient hierarchically structured composites containing cobalt catalyst for clean synthetic fuel production from Fischer–Tropsch synthesis

Abstract

Co zero field NMR a b s t r a c tWe report a straightforward preparation method to synthesize hierarchical composite consisting of TiO 2coated multi-walled carbon nanotubes (CNTs) decorating a macroscopic host structure of a-Al 2 O 3 . The obtained composite possesses moderate specific surface area and very open porous structure, as well as moderate interaction with active sites, which significantly improve the cobalt nanoparticles dispersion and the mass diffusion during the reaction. The Co/TiO 2 /CNT-a-Al 2 O 3 (CoTiCNTA) catalyst is then used in the Fischer-Tropsch synthesis (FTS) process. This hierarchical catalyst achieves a FTS rate to C 5+ of 0.80 g C5+ g cat À1 h À1 along with a long-chain hydrocarbons (C 5+ ) selectivity of 85%, which can be pointed out as the most outstanding noble promoter-free catalyst for the FTS process. The as-synthesized catalyst also exhibits an extremely high stability as a function of time on stream which is also one of the prerequisites for the development of future FTS catalysts, especially for the Biomass-to-Liquids process where trace amount of impurities and/or moisture could have an impact on the catalyst stability. The present work also introduces a new investigation methodology based on the use of zero field 59 Co NMR, which allows one to map in a precise manner the cobalt active phase distribution and to correlate it with the FTS performance. It is expected that such technique would be extremely helpful for the understanding of the catalyst structure-performance relationship and for future optimization in the FTS process as well as in other fields of investigation where cobalt particles are involved.

On the Way to a More Open Porous Network of a Co–Re/Al2O3 Catalyst for Fischer–Tropsch Synthesis: Pore Size and Particle Size Effects on Its Performance

“…Macroporosity of catalyst improves the CO transport rate from the gas phase to the active sites through the liquid hydrocarbons filling the catalyst pores. The benefits of macroporosity incorporation into other supports for FTS catalysts (ZrO 2 , SiO 2 , CNTs, nanofibrous alumina) have been previously observed by other authors [16,[24][25][26].…”

“…Recently, Liu et al [24] have developed a new hierarchical composite support of TiO 2 -coated carbon nanotubes (CNTs) grown over a-Al 2 O 3 . They indicated that this support considerably improves transport properties of reactants and products achieving FTS rates of 0.80 g C5?…”

Synthesis of hierarchically porous metal oxides and Au/TiO2 nanohybrids for photodegradation of organic dye and catalytic reduction of 4-nitrophenol

“…Interest in this kind of materials is growing rapidly in recent years due to their intriguing characteristics in various applications including catalysis [1,2], sensors [3], adsorption [4], and energy conversion and storage [5,6]. In particular, the performance of hierarchically porous metal oxides in catalysis/photocatalysis is expected to be greatly improved over that of their counterparts with only one type of porosity [7,8].…”

Carbon Spheres Prepared by Hydrothermal Synthesis—A Support for Bimetallic Iron Cobalt Fischer–Tropsch Catalysts

“…[1,2] These carbon sources provide alternative non-crude-oil routes for the synthesis of petrol, diesel and chemicals. FT synthesis thus continues to receive attention from researchers, which has led to many technical advances in the FT process.…”