Jiaqiang Sun

Morphology effect of one-dimensional iron oxide nanocatalysts on Fischer–Tropsch synthesis

One-dimensional iron oxide nanocatalysts have been fabricated by a facile, one-step hydrothermal method. The nanotubes show distinguished catalytic activity and selectivity to heavy hydrocarbons compared to other Fe catalyst morphologies. This can be attributed to their shape anisotropy, mesoporous structure and stable chemical phase under reaction conditions. The nanotubes facilitate the formation of active iron carbides unlike nanorods, which further improve the catalytic activity. The nanotubes also show high activity due to the interactions between the inside surface of the cavity and the reactant. Furthermore, the pore structure of the nanotubes would also influence the selectivity. This strategy results in efficient control of the chain length distribution in the Fischer–Tropsch synthesis due to the steric restrictions on the growth of hydrocarbons. To some extent, the morphology-dependent nanocatalysts bridge the gap between real catalysts in practical applications and model catalysts used in surface science.

The effect of the unpaired d-orbital electron number in Fe and Co catalysts on Fischer–Tropsch synthesis

The unpaired d electron number is a significant parameter in designing highly active and selective catalysts. In this communication, we take Fe- and Co-based catalysts as examples. The unpaired d electron number was calculated, and the results show that it can be used as an indicator to select electron promoters for different catalysts.

A Novel Hydrothermal Approach for the Synthesis of Flower-Like Fe2O3/Fe Foam Nanocrystals and Their Superior Performance in Fisher–Tropsch Synthesis

A novel and facile hydrothermal approach was developed for the synthesis of three-dimensional flower-like α-Fe2O3 nanocrystals grown directly on Fe substrate using Fe(NO3)3 and hexamethylenetetramine as precursors in aqueous medium. A reaction mechanism for the synthesis and growth of the flower-like α-Fe2O3 nanocrystals was proposed to explain the effects of reaction time and temperature on the morphology and structure of the as-synthesized nanocrystals. Moreover, cube-like shapes of Fe2O3 nanocrystals were produced when urea used as hydrolysis reagent during the synthesis process. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were employed to confirm the unique morphology, high crystallinity and pure phase structure. The as-synthesized flower-like α-Fe2O3 nanocrystals displayed a higher activity and C2–4 olefin/paraffin ratio in Fisher–Tropsch synthesis than the cube-like shape of α-Fe2O3 nanocrystals, possibly due to their high specific surface area as well as diversity of catalytic active sites.Graphical AbstractThe produced flower-like Fe2O3 nanocrystals sample displayed high catalytic activity and C2-4 olefin/paraffin over the cube-like Fe2O3 nanocrystals for Fischer-Tropsch synthesis, due to the high specific surface area and diversity of catalytic active sites.

Design and construction of Ni3−xCoxO4 nanorods grown on Ni foam for tuning synthetic natural gas heating values

Ni3−xCoxO4 nanorods with different Ni/Co ratios were fabricated on Ni foam using a controllable process. The conversion of CO for Ni2CoO4 nanorods was the highest during the whole methanation reaction process. The design of the Ni3−xCoxO4 nanorods with different Ni/Co ratios is the origin of the different catalytic activity. The synergistic effect of Ni and Co also tunes the product selectivity, thus controlling the heating value of synthetic natural gas. The nanorods directly grown on the Ni foam can ensure efficient anchoring of the nanorods. The designed synthesis of the Ni3−xCoxO4 nanorods with different Ni/Co ratios provides a new strategy for controlling the catalytic activity and selectivity of syngas methanation.

Sol-Gel Autocombustion Combined Carbothermal Synthesis of Iron-Based Catalysts for the Fischer-Tropsch Reaction

A new combined method of sol–gel autocombustion with carbothermal reduction has been developed to synthesize Fe‐based Fischer–Tropsch synthesis (FTS) catalysts. The effect of the glucose content on the structure and texture of the Fe phase is investigated. The glucose is employed as a reducing and carburizing agent to control the phase transformation of the Fe precursors. The reducibility of the synthesized iron oxide increases with the increase of the proportion of glucose. Meanwhile, iron oxide is converted completely into iron carbide in the presence of abundant glucose. The addition of glucose to the precursor is conducive to construct active sites before the FTS reaction. However, excess glucose results in carbon deposition and a poor FTS performance. Iron carbide also could be synthesized by this new method and will be applied directly to the FTS reaction in further research.

CoFe 2 O 4 nanoarray catalysts for Fischer-Tropsch synthesis

Abstract CoFe 2 O 4 nanoarray catalysts were fabricated on iron foam by a controlled process involving the hydrothermal growth and calcinations of iron-doped cobalt carbonate hydroxide hydrate (CoFe-CHH) nanowires precursors. The crystalline phase, microstructure and component of CoFe 2 O 4 nanoarrays were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The produced catalysts were used for Fischer-Tropsch synthesis and the nanoarray catalysts displayed a high CO conversion rate of 69% at 5 L/g/h and a better performance than powder catalysts.