Tuning selectivity in low-temperature Fischer-Tropsch synthesis by applying gas recycle mode

• Published in: Applied catalysis. A, General General, 2024-04, Vol.675, p.119641, Article 119641
• Main Authors: Mitchenko, Sergey, Yakovenko, Roman, Soromotin, Vitaliy, Krasnyakova, Tatyana, Svetogorov, Roman, Rusalev, Yuri
• Format: Article
• Language: English
• Subjects: C19+-Heavy waxes; C5+ Olefins; Catalyst deactivation; Cobalt catalyst; Fischer-Tropsch synthesis; Process deselectivation
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2024.119641

While hydrocarbons production by Fischer-Tropsch synthesis (FTS) is widely recognized, commercial interest in FTS products is mainly constrained by oil prices. The FTS-derived fuels, although higher quality and greener, cannot currently compete with cheaper fossil fuels, motivating to shift the FTS products distribution to higher value-added chemicals, such as olefins-C5+. The high olefin selectivity in FTS over Co-based catalysts is usually ascribed to Co2C on the catalyst surface with its inherent deficiencies. This study demonstrates a novel approach to alter low-temperature FTS selectivity by applying off-gas recycling. At slow gas recycling rates, C19+ selectivity increases due to re-adsorption and re-incorporation into the growing chain of gaseous olefins from the off-gas. High-intensity gas recycling facilitates C5+ olefin vapors removal from the reactor by enhanced gas flow with their subsequent cut-off in the cold trap, thus reducing residence time of condensed olefins and probability of their secondary reactions. [Display omitted] •Tail gas recycling is an apt tool to tune selectivity of Fischer-Tropsch synthesis.•C19+ selectivity rises at low gas recycle ratios due to light olefins re-adsorption.•At high gas recycle ratios, selectivity to olefins rises at the cost of heavy waxes.•Gas recycle mode speeds up the reduction of residual CoO in the catalyst by syngas.