Fischer–Tropsch synthesis, the effect of promoters, catalyst support, and reaction conditions selection

A Review of Theoretical Studies on Carbon Monoxide Hydrogenation via Fischer-Tropsch Synthesis over Transition Metals

The increasing demand for clean fuels and sustainable products has attracted much interest in the development of active and selective catalysts for CO conversion to desirable products. This review maps the theoretical progress of the different facets of most commercial catalysts, including Co, Fe, Ni, Rh, and Ru. All relevant elementary steps involving CO dissociation and hydrogenation and their dependence on surface structure, surface coverage, temperature, and pressure are considered. The dominant Fischer-Tropsch synthesis mechanism is also explored, including the sensitivity to the structure of H-assisted CO dissociation and direct CO dissociation. Low-coordinated step sites are shown to enhance catalytic activity and suppress methane formation. The hydrogen adsorption and CO dissociation mechanisms are highly dependent on the surface coverage, in which hydrogen adsorption increases, and the CO insertion mechanism becomes more favorable at high coverages. It is revealed that the chain-growth probability and product selectivity are affected by the type of catalyst and its structure as well as the applied temperature and pressure.

Catalytic co-pyrolysis of herb residue and polypropylene for pyrolysis products upgrading and diversification using nickel-X/biochar and ZSM-5 (X = iron, cobalt, copper)

It is very important to find cheap and efficient catalysts for catalytic co-pyrolysis. Catalytic co-pyrolysis of herb residue (HR) and reused polypropylene (PP) using Ni-X/biochar and ZSM-5 (X = Fe, Co, Cu) was performed to produce pyrolysis oil, pyrolysis gas and carbon nanotubes (CNTs) in a two-stage fixed bed reactor. Bimetallic biochar catalysts exhibited higher catalytic activity due to their higher specific surface area (S_BET) and more strong acid sites. NiCu/biochar significantly increased the yield of pyrolysis oil by enhancing Fischer-Tropsch synthesis. In addition, the stronger secondary cracking capacity of NiCu/biochar resulted in the highest content of hydrocarbons (80.47%) and C6-C11(61.10%), while the availability of higher content of carbon source gas also facilitated the formation of CNTs and H₂ at back-end. The cheap and efficient NiCu/biochar catalyst has great potential in the application of catalytic pyrolysis, which is conducive to the large-scale promotion of biomass pyrolysis technology.

Microwave modification of iron supported on beta silicon carbide catalysts for Fischer–Tropsch synthesis

Beta silicon carbide is a good microwave absorber support. Microwave irradiation can improve the surface properties of Fe/β-SiC catalysts. Microwave irradiation can be used to improve the catalytic performance of Fe/β-SiC catalysts.