CO2 hydrogenation to light olefins over mixed Fe-Co-K-Al oxides catalysts prepared via precipitation and reduction methods,Chemical Engineering Journal

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CO2 hydrogenation to light olefins over mixed Fe-Co-K-Al oxides catalysts prepared via precipitation and reduction methods
Chemical Engineering Journal ( IF 13.3 ) Pub Date : 2021-07-22 , DOI: 10.1016/j.cej.2021.131389
Thongthai Witoon _{1,

2} , Vittawin Lapkeatseree ₁ , Thanapha Numpilai _{1,

2} , Chin Kui Cheng ₃ , Jumras Limtrakul ₄

Affiliation

A series of Fe-Co-K-Al oxides catalysts were prepared by precipitation-reduction method using NHOH as precipitating agent and NaBH as reducing agent. The effect of preparation methods including one-pot preparation (C1), without the addition of NHOH (C2), precipitation followed by reduction (C3) and doubling NaBH content of C3 (C4) on the physicochemical properties of the catalysts as well as their catalytic CO hydrogenation to light olefins was investigated. The preparation methods had a significant influence on phase, reducibility and the amount and strength of CO and H adsorption with the catalysts surface. The structure–activity relationships indicated that the CO conversion was proportional to the amount of medium CO adsorption sites, while the O/P ratio increased with decreasing the amount of weak H adsorption sites. The C3 catalyst exhibited the highest light olefins yield of 16.58% at 350 °C and 20 bar. This was attributed to a significant reduction of weak adsorption of H, while maintaining a high level of medium CO adsorption, inhibiting the hydrogenation of olefins to paraffins products and providing the relatively high CO conversion, respectively. Replacing the reducing gas from H to a gas mixture containing H and CO of the C3 catalyst (C5) was unable to reduce the iron species to metallic Fe, resulting in the formation of FeC which was less active for the production of hydrocarbon compared to FeC phase formed in the C3 catalyst.

中文翻译：

沉淀还原法制备的 Fe-Co-K-Al 混合氧化物催化剂上 CO2 加氢制轻质烯烃

以NH4OH为沉淀剂、NaBH2为还原剂，采用沉淀还原法制备了一系列Fe-Co-K-Al氧化物催化剂。一锅法制备(C1)、不添加NH4OH(C2)、沉淀还原还原(C3)和C3中NaBH含量加倍(C4)等制备方法对催化剂理化性能及其性能的影响研究了CO催化加氢制轻质烯烃的方法。制备方法对催化剂的物相、还原性以及催化剂表面CO和H的吸附量和强度有显着影响。结构-活性关系表明，CO转化率与中等CO吸附位点的数量成正比，而O/P比随着弱H吸附位点数量的减少而增加。 C3催化剂在350℃和20bar下表现出最高的轻质烯烃产率16.58%。这归因于H的弱吸附显着减少，同时保持了高水平的中等CO吸附，抑制了烯烃加氢为烷烃产物并提供了相对较高的CO转化率。将 C3 催化剂 (C5) 的还原气体从 H 替换为含有 H 和 CO 的气体混合物，无法将铁物质还原为金属 Fe，导致形成 FeC，与 FeC 相比，FeC 对于碳氢化合物的生产活性较低在C3催化剂中形成相。

更新日期：2021-07-22

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