Fischer–Tropsch Synthesis Using Zeolite-supported Iron Catalysts for the Production of Light Hydrocarbons

Abstract

Fischer-Tropsch synthesis (FTS) for the production of olefins from syngas was investigated on FeCuK impregnated on zeolite catalysts such as ZSM-5, Mordenite and Beta-zeolite. ZSM-5 supported catalyst showed the best activity among the three catalysts due to the high reducibility of iron oxides. It also exhibited high olefin selectivity compared to a catalyst prepared by physical mixing of the two components, due to the presence of moderate number of acid sites.

Exploring Iron‐based Multifunctional Catalysts for Fischer–Tropsch Synthesis: A Review

“…Similarly, a recent study by Kang et al showed that, although an impregnated catalyst Fe/Cu/K/ZSM-5 had a slightly lower CO conversion with respect to one prepared by physical mixing of the two components, the former exhibited a higher affinity and thus produced more olefins (Figure 3). [130] In addition, the initial conversion was very low on physically mixed catalysts and showed an increasing trend with time-on-stream compared to the impregnated catalyst, which displayed a much higher initial activity (Figure 2). These effects are attributable to the different dispersion of the active phase caused by the preparative methods.…”

“…Various methods have been used to introduce iron, such as the addition of the metal precursor into the synthesis gel, [129,135] ion exchange, [131,136] impregnation, [114,130] vapor phase deposition, [101] or physical mixing of the zeolite with the iron precursor [102][103][104]127] or iron catalyst. [120] The catalytic performance of the resulting catalysts strongly depends on the prep- aration method, resulting in iron species located at considerably different positions in the support.…”

“…Most authors used this method to gain a better understanding of the influence of the zeolite on the activity of the iron-based catalyst [103,120,121] because of the ease of preparation. [121] Impregnation is often chosen to achieve a high metal loading, [114,130] but it generally leads to a less-dispersed catalyst. This strongly affects the selectivity of the FTS products.…”

“…Smaller crystallite sizes of the zeolites reduces the extent of deactivation (vide infra) www.chemsuschem.org owing to an improved diffusion of aromatics, which prevents their accumulation and transformation into coke. [104] The effect of the acidity, dimensionality, and zeolite topology on the activity and selectivity of the FTS process was also studied by Kang et al [130] The impregnation of beta (Si/Al = 12.5), mordenite (Si/Al = 6), or H-ZSM-5 (Si/Al = 25) zeolites with a Fe/ Cu/K solution was performed to produce light olefins. Among these materials, the ZSM-5-supported catalyst exhibited the best FTS activity (at 300 8C and 10 bar, Figure 2) because of the higher reducibility of iron oxides over this support, and therefore, a higher number of active carbide species could be formed.…”

“…Although some studies noticed an increased amount of hydrocarbons in the gasoline range if the zeolite was impregnated with the iron precursor, [129] the contrary applies to other studies, which showed a higher amount of olefins in the C 2 -C 4 range by using the same preparation method. [130] These observations were clearly influenced by a variability in the experimental procedures and emphasize the necessity to expand the number of studies related to multifunctional catalysts to establish clear structure-performance relationships. In this regard, the textural properties of the zeolites are also an interesting point for selective transformations.…”