Catalyst development for selective conversion of syngas to mainly aromatic hydrocarbons

Abstract

The paper describes the following catalytic systems tested in the Fischer‐Tropsch reaction and characterized by XPS, TEM, and CO chemisorption: (i) Fe/Mn oxides impregnated with Co, Cu, Pd, Rh and K, respectively, (ii) Co/Mn oxide catalysts with different compositions to maximize the formation of olefinic products. The impregnation of Fe/Mn oxides with Cu and a Co/Mn ratio of 1:4 led to the most promising catalysts. (iii) Rh/SiO2 catalysts doped with rare earth compounds and ThO2 to maximize the formation of oxygenates (iv) Mixtures of the catalysts (i), (ii), or (iii) with pentasil zeolites to form aromatic hydrocarbons. Two modes of operation were tested, namely a single‐bed reactor with a mechanical mixture of the components, and a dual‐bed operation with the FT component and the zeolite, respectively, in separate reactors. The optimal zeolite for the formation of the aromatics from propene was determined. A knowledge‐based expert system for catalyst selection was developed.

Recent Advances in Direct Synthesis of Value‐Added Aromatic Chemicals from Syngas by Cascade Reactions over Bifunctional Catalysts

“…Compared to the Cu–Zn and Pd‐based bifunctional catalysts, the Cr–Zn/HZSM‐5 or Zn–ZrO 2 /HZSM‐5 can transform completely the formed intermediates (oxygenates) to aromatics, which seems to be attributed to a combined acidic site effect of the HZSM‐5 and metal oxides (slightly acidic nature). Although favoring WGS activity, Fe‐based catalysts have been frequently used and modified for the synthesis of aromatic monomers from syngas at an optimal FTS reaction temperature of Fe‐based catalysts, which is very close to an optimal temperature for oligomerization, cracking, isomerization and aromatization reaction of the solid‐acid HZSM‐5 …”

“…For instance, methanol, DME and olefins intermediates formed from syngas on metal components by COx hydrogenation are converted into aromatics exclusively on the HZSM‐5 either by a single‐bed catalyst, where two catalytic components are constructed under the same working conditions or dual‐bed catalysts in which two catalytic components separated through quartz wool spacer in a same tubular reactor ( Figure a) . Besides, a dual catalytic‐bed arrangement with separate reactors, where the active metal and zeolite components can work in different temperatures, are also reported in order to regenerate both components independently . As compared to a dual‐bed STA process (ie., both components in a single‐bed reactor or separate reactors), a single‐bed STA process, which concurrently triggers the intermediate formation by in situ aromatization, is combined in a single reactor using bifunctional catalysts where the two active components are close to each other with synergetic effects (Figure b,c).…”

A comparative study of two H2-redistribution strategies along the FT reactor using H2-permselective membrane

“…To promote the yield and quality of the gasoline from FT synthesis, bifunctional catalysts have received extensive attention in the recent years [5,6]. In addition, a knowledge-based expert system for catalyst selection was developed by Baerns and coworkers [7].…”

The addition of HZSM-5 to the Fischer–Tropsch process for improved gasoline production

“…The range of FT catalysts include those based on iron [6][7][8][9], iron/manganese [10,11], cobalt [12,13], cobalt/manganese [14,15] and even iron/cobalt [16]. The use of different zeolites (mordenite, erionite, ZSM-11, ZSM-12, L, omega and beta) in combination with a Fischer-Tropsch catalyst has been investigated [17], while other researchers tested HZSM-5 [6,16], gallium-substituted HZSM-5 [14,15] and HY [10]. The two catalytic functions have also been combined in a variety of ways, ranging from a single reactor containing both catalytic functions (taking advantage of a possible synergistic effect between the two catalysts) to a dual reactor arrangement with the two catalytic functions in subsequent reactors (so that the operating parameters of the reactors can be optimised individually).…”