Stable and Selective Dehydrogenation of Methylcyclohexane using Supported Catalytically Active Liquid Metal Solutions – Ga₅₂Pt/SiO₂ SCALMS

Abstract

The use of gallium-rich, Supported Catalytically Active Liquid Metal Solution (SCALMS) is a promising new concept to achieve catalysis with atomically dispersed active metal atoms. Expanding our previous work on short alkane dehydrogenation, we present here the application of SCALMS for the dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) using a Ga 52 Pt alloy (liquid under reaction conditions) supported on silica. Cycloalkane dehydrogenation catalysis has attracted great attention recently in the context of hydrogen storage concepts using liquid organic hydrogen carrier (LOHC) systems. The system under investigation showed high activity and stable conversion of MCH at 450°C and atmospheric pressure for more than 75 h time-on-stream (X MCH = 15 %) with stable toluene selectivity (S TOL) of 85 %. Compared to commercially available Pt/SiO 2 , the SCALMS system resulted in higher yields and robustness. Baseline experiments with Pt-free Ga/SiO 2 under identical conditions revealed the decisive influence of Pt dissolved in the liquid Ga matrix.

GaPt Supported Catalytically Active Liquid Metal Solution Catalysis for Propane Dehydrogenation–Support Influence and Coking Studies

“…The concept of supported catalytically active liquid metal solutions (SCALMS) was recently introduced for high-temperature catalysis . Herein, a low melting and typically catalytically inactive metal (e.g., Ga) is doped with a small amount of a catalytically active metal (e.g., Pd, Rh, Pt), − and the resulting bimetallic alloy is deposited onto a porous support. The SCALMS material concept is shown schematically in Figure .…”

Recent Advances in Catalysts and Membranes for MCH Dehydrogenation: A Mini Review

“…Other recently emerging but similar ideas were presented, where researchers added a second or third metal to platinum. For example, Nakaya et al employed the addition of iron and zinc [52], Zhang et al added copper [53], while Sebastian et al added gallium but the reaction was conducted under liquid alloy condition supported on silica [54] which is a new concept. The testing conditions of the three catalysts were in a similar vicinity of around 400-450 • C at 1 bar.…”

Tuning the Interaction between Pd and MgAl2O4 To Enhance the Dehydrogenation Activity and Selectivity of Dodecahydro-N-ethylcarbazole

“…As hydrogen storage carriers, unsaturated organic matters have the advantages of high hydrogen storage density, suitable for long-distance transportation, good safety, large-scale recycling, etc . Common liquid organic hydrogen carriers include toluene, , dibenzyltoluene, N -ethylcarbazole (NEC), , N -propylcarbazole, , decalin, etc., in which NEC is considered the most competitive candidate due to its hydrogenation and dehydrogenation reactions at temperatures below 473 K. The complete hydrogenation product of NEC is dodecahydro- N -ethylcarbazole (12H-NEC), and the hydrogen storage capacity of the NEC/12H-NEC system is 5.79 wt %. The hydrogenation and dehydrogenation reactions can be carried out on oxide-supported noble metal catalysts (for example, Ru, Pt, and Pd), among which Ru-based catalysts are more conducive to the occurrence of hydrogenation reactions, and Pt-based and Pd-based catalysts are more conducive to dehydrogenation reactions. − Three dehydrogenation products are produced during the dehydrogenation of 12H-NEC, including 8H- N -ethylcarbazole (8H-NEC), 4H- N -ethylcarbazole (4H-NEC), and N -ethylcarbazole, and the reaction pathway is shown in Figure .…”