Enhanced Production of C2–C4 Olefins Directly from Synthesis Gas

Abstract

An attempt made for the selective production of C 2 -C 4 olefins directly from the synthesis gas (CO + H 2 ) has led to the development of a dual catalyst system having a Fischer-Tropsch (K/Fe-Cu/AlOx) catalyst and cracking (H-ZSM-5) catalyst operate in consecutive dual reactors. The flow rate (space velocity) and H 2 /CO molar ratio of the feed have been optimized for achieving higher CO conversions and olefin selectivities. The selectivity to C 2 -C 4 olefins is further enhanced by optimizing the reaction temperature in the second reactor (cracking), where the product exhibited 51% selectivity to C 2 -C 4 hydrocarbons rich in olefins (77%) with a stable time-on-stream performance in a studied period of 100 h.

Effect of Active Component Contents to Catalytic Performance on Fe-Cu-K/ZSM5 Fischer-Tropsch Catalyst

“…In the previous investigation, we have also reported the detailed studies on Fe-Cu-K/zeolites FTS catalysts with respect to its effects on reducibility, active phase formation such as surface carbides and its influence on catalyst performance such as CO conversion, water gas shift (WGS) activity and product distribution [6][7][8][9][10]. Furthermore, since the acidic sites on ZSM5 component could help to enhance C 2 -C 4 selectivity by the presence of olefin cracking activity of FTS products reported by our previous work [11], the selection of appropriate ZSM5 components (Si/Al = 25) on the iron-based Fischer-Tropsch catalyst is adopted in the present investigation to obtain high catalytic performance. The optimum weight ratio of Fe/Cu is found to be around 1/0.1 on bifunctional catalyst containing ZSM5 and the increase of K component in the coprecipitated iron-based FTS catalyst are mainly responsible for the enhanced olefin selectivity as reported in our previous works [7,8].…”

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

“…[118] The use of zeolites in FTS has been tackled by using the zeolite as support for the active metal, [119] by directly mixing the iron catalyst with the zeolite cocatalyst, [12,120] or by using it as hydrocracking catalyst in a separate downstream wax-hydrocracking unit. [121][122][123][124] To emphasize the multifunctional character of a single catalyst (FT activity+zeolite), studies performing the FT reaction in consecutive dual reactors will not be considered. Iron catalysts supported on microporous zeolites, such as ZSM-5, mordenite, beta, or zeolite X or Y, exhibit a distinct activity as a function of the zeolite structure.…”

Catalytic Performance for Hydrocarbon Production from Syngas on the Promoted Co-Based Hybrid Catalysts; Influence of Pt Contents

“…The high content of weak acidic sites is also responsible for high yields to C5-C9 hydrocarbons, due to the possible catalytic cracking of higher molecular-weight olefins on acidic sites of zeolites [18,19]. As reported in our previous work, the physically-mixed ironbased FTS catalyst with ZSM-5 showed a high selectivity to byproducts and a low selectivity to olefinic hydrocarbons [22].…”

“…CO conversion and product distribution on promoted CoAl2O3/ZSM-5 catalysts are presented at steadystate average values of CO conversion and product distribution after 30 h. In general, the catalyst having a large surface area with a large pore diameter is beneficial for obtaining a small cobalt crystallite size and facile transport of heavy hydrocarbons formed during FTS reaction. The large pores on FTS catalysts have been suggested to be linked to less coke or wax deposition [22]. The high content of weak acidic sites is also responsible for high yields to C5-C9 hydrocarbons, due to the possible catalytic cracking of higher molecular-weight olefins on acidic sites of zeolites [18,19].…”