Chain Propagation Mechanism of Fischer–Tropsch Synthesis: Experimental Evidence by Aldehyde, Alcohol and Alkene Addition

Fischer–Tropsch synthesis (FTS) produces hundreds of hydrocarbons and oxygenates by simple reactants (CO + H2) and the detailed chain propagation mechanism is still in dispute. An industrial iron-based catalyst was used to further clarify the mechanism by adding aldehyde, alcohol and alkene species into a fixed-bed tubular reactor. The added species were investigated in H2 and syngas atmospheres, respectively. 1-alkene in the H2 atmosphere presented an obvious hydrogenolysis, in which the produced C1 species participated in C–C bond formation simultaneously. Co-feeding Cn alkene with syngas showed remarkable Cn+1 alcohol selectivity compared to the normal FTS reaction. In addition, the carbonyl group of aldehyde was extremely unstable over the iron-based catalyst and could easily be hydrogenated to an alcohol hydroxyl group, which could even undergo dehydration for hydrocarbon species formation. Experimental data confirmed that both heavier alkenes and alcohols added can be converted to chain growth intermediates and then undergo monomer insertion for chain propagation. These results provide strong evidence that the chain propagation in the FTS reaction is simultaneously controlled by the surface carbide mechanism and the CO insertion mechanism, with surface CHx species and CO as monomers, respectively. The study is of guiding significance for FTS mechanism understanding and kinetic modeling.

Morphology evolution with polymer chain propagation and its impacts on device performance and stability of non-fullerene solar cells

Blending morphology evolves with polymer chain propagation with reduced phase separation scale and increased phase purity while blending morphological stability is dominated by the miscibility between the donor and acceptor.

A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry

Aminoalkyl radicals can be used as both initiators and chain-carriers for the conversion of aryl halides into the corresponding radicals. This approach by-passes the requirement for strongly reducing photocatalysts.

Chain propagation determines the chemo- and regioselectivity of alkyl radical additions to C–O vs. C–C double bonds

Reversible radical addition followed by an irreversible electron transfer leads to regio- and chemoselectivity control of radical additions to π-systems.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp³) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp³)-H bonds.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp³) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp³)-H bonds.