Synthesis of K-Cr@alumina Catalysts for Isobutane Dehydrogenation and Membrane Reactor Applications

IF 2.3 4区化学 Q3 CHEMISTRY, PHYSICAL

Catalysis Letters Pub Date : 2025-04-04 DOI:10.1007/s10562-025-04990-1

Meltem Dogan, Hatice Kara Acat, Saliha Cetinyokus

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Abstract

In this study, it was aimed to enrich the feed stream in the FCC (Fluid Catalytic Cracking) unit outlet by isobutane dehydrogenation. A gas mixture consisting of 15 mol% isobutane, 15 mol% isobutene, 15 mol% hydrogen, and 55 mol% helium was used as the feed stream. Reactions were performed in a fixed bed reactor system containing a Pd alloy membrane by creating a pressure difference of 70 kPa between the two sides of the membrane at 550 °C and 600 °C. Catalysts containing 8% Cr by mass and a Cr/K ratio of three were prepared by impregnation technique using alumina supports. The highest amount of monochromate was determined in the catalyst where K was loaded onto the support first. It is known that the most active form for dehydrogenation reactions in chromium-based catalysts is monochromate. It was shown that monochromatic structures were increased by adding potassium. The equilibrium conversions were exceeded at both temperatures. In the catalytic tests carried out at WHSV (Weight Hourly Space Velocity) values corresponding to two different retention times (0.3 h⁻¹ and 0.5 h⁻¹), lower isobutene yield values were obtained when the retention time was increased. The amount of monochromate in the catalyst structure was preserved with the help of water formed during the reaction. The decrease in isobutene yield values during the reaction was explained by isobutene decomposition and coke formation. It was also shown that the excess hydrogen in the medium caused the hydrogenation of propane as well as isobutane hydrogenation.

Graphical abstract

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K-Cr@alumina异丁烷脱氢催化剂的合成及膜反应器应用

本研究旨在通过异丁烷脱氢来丰富FCC（流体催化裂化）装置出口进料流。用15 mol%异丁烷、15 mol%异丁烯、15 mol%氢和55 mol%氦组成的混合气体作为进料流。在固定床反应器系统中，通过在膜的两侧在550℃和600℃下产生70 kPa的压差进行反应。以氧化铝为载体，采用浸渍法制备了Cr质量分数为8%、Cr/K比为3的催化剂。在先将K负载到载体上的催化剂中，单色酸盐的含量最高。众所周知，在铬基催化剂中脱氢反应最活跃的形式是单铬酸盐。结果表明，钾的加入增加了单色结构。在两个温度下都超过了平衡转化。在两种不同保留时间（0.3 h−1和0.5 h−1）对应的WHSV（重量小时空速）值下进行的催化试验中，随着保留时间的增加，异丁烯产率值降低。在反应过程中形成的水的帮助下，催化剂结构中单色酸盐的数量得以保存。反应过程中异丁烯产率降低的原因是异丁烯的分解和焦炭的形成。实验还表明，介质中过量的氢引起丙烷的加氢和异丁烷的加氢。图形抽象

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来源期刊

Catalysis Letters 化学-物理化学

CiteScore

5.70

自引率

3.60%

发文量

327

审稿时长

1 months

期刊介绍： Catalysis Letters aim is the rapid publication of outstanding and high-impact original research articles in catalysis. The scope of the journal covers a broad range of topics in all fields of both applied and theoretical catalysis, including heterogeneous, homogeneous and biocatalysis. The high-quality original research articles published in Catalysis Letters are subject to rigorous peer review. Accepted papers are published online first and subsequently in print issues. All contributions must include a graphical abstract. Manuscripts should be written in English and the responsibility lies with the authors to ensure that they are grammatically and linguistically correct. Authors for whom English is not the working language are encouraged to consider using a professional language-editing service before submitting their manuscripts.