Pt-Based Carbon Fiber Catalytic Dehydrogenation of Methylcyclohexane in a Fixed-Bed Reactor

Abstract

In this study, carbon fibers (CF) were modified by gas-phase (G), liquid-phase (L), and gas–liquid-phase (GL) oxidation methods, on which the platinum (Pt) was further loaded to prepare catalysts of Pt/CF-G, Pt/CF-L, and Pt/CF-GL, respectively. The fluffy stacking of one-dimensional fibrous catalysts endowed Pt/CF-G, Pt/CF-L, and Pt/CF-GL with excellent mass transfer efficiency, enabling them to self-support and directly be used in a fixed bed. Compared with primary CF, the oxygen content on the surface of CF-GL increased by 75.2%. The increase in the oxygen-containing groups on the surface of CF-GL not only facilitated the Pt atoms anchoring (enhancing the Pt loading from 1.76 to 2.44%) but also effectively improved the dispersion of Pt particles (reducing the Pt nanoparticle size from 4.68 to 3.73 nm). The catalyst Pt/CF-GL had the high catalytic activity and achieved the conversion rate of 96.9% during the methylcyclohexane (MCH) dehydrogenation reaction process (28.9, 47.0, and 76.1% for the Pt/CF, Pt/CF-L, and Pt/CF-G catalyst, respectively). Moreover, the catalyst Pt/CF-GL exhibited excellent activity stability after 72 h of continuous MCH dehydrogenation reaction, with a very low inactivation rate (<5%). Obviously, the self-supporting Pt/CF-GL catalyst could be directly used for efficient and stable dehydrogenation of liquid organic hydrogen carriers.