Enhanced Activity and Stability of a Carbon‐Coated Alumina‐Supported Pd Catalyst in the Dehydrogenation of a Liquid Organic Hydrogen Carrier, Perhydro 2‐(n‐methylbenzyl)Pyridine

Abstract

The activity and stability of supported Pd catalysts are of crucial importance in the dehydrogenation of perhydro 2‐(n‐methylbenzyl)pyridine (H12‐MBP) reported as a potential liquid organic hydrogen carrier. Because of good stability examined in many hydroprocessing reactions, carbon‐coated alumina (CCA) was chosen as a support for Pd loading and prepared by the pyrolysis of glycerol solution with different concentrations. The catalytic activity and stability of Pd/CCA catalysts exhibited a volcano‐shaped relationship with the carbon content. Various characterization results revealed that the degree of carbon coating affected the acidity, Pd loading and particle size, reactant adsorption capacity, and H2 release at low temperatures. At an optimal carbon content (3.3 wt % in this work), these properties are believed to be balanced well, thus showing the best catalytic performance. Moreover, the improvement of catalytic activity was examined with supported Pd on carbon‐coated silica‐alumina of 3.3 wt % carbon content.

Dehydrogenation of 2-[(n-Methylcyclohexyl)Methyl]Piperidine over Mesoporous Pd-Al2O3 Catalysts Prepared by Solvent Deficient Precipitation: Influence of Calcination Conditions

“…The reduced MPdA catalyst was tested for the dehydrogenation of H 12 -MBP in a batch reactor (volume: 90 cm 3 ) described previously [9,12,13]. In a typical experiment, H 12 -MBP of 7.3 mmol was added dropwise to the MPdA catalyst pre-loaded at the bottom of the reactor vessel, where the catalyst weight was varied to obtain a desired metal-to-reactant (M/R) ratio.…”

“…However, the Pd/C catalyst fails to retain its dehydrogenation efficiency compared to Pd/Al 2 O 3 (showing a slight activity loss) in stability tests because of the accumulation of Pd particles. In the search for stable catalysts, carbon coated Al 2 O 3 supported Pd catalysts were considered for the dehydrogenation of H 12 -MBP and it was noted that a 3.3 wt% carbon coated catalyst exhibited enhanced stability compared to those of other catalysts owing to the control of Pd particle growth by the heterogeneous support surface [13]. Nevertheless, this approach is complex and the final carbon content depends on the textural and acidic properties of the alumina used for the carbon coating.…”

Sacrificial carbonaceous coating over alumina supported Ni–MoS2 catalyst for hydrodesulfurization

“…10,14,15 The varied functional groups on the carbon materials could be tailored by oxidizing agents during the preparing process, which is very different from the surface chemistry of alumina. [16][17][18][19] As a consequence, catalysts prepared with carbon as support (active carbon or graphene) were more active than their alumina-supported counterparts. [20][21][22] However, the signicant disadvantage of carbon supports for low packing density limits their application in commercial HDT catalyst formulations.…”

“…In some other cases, interactions between the loaded metal and support (carbon materials) may cause serious sintering problems under reaction conditions. 17 In order to properly alter the interaction between active component and supporting material, alumina supported systems with carbon 11,27 were found to be more preferred to apply in certain reaction systems. Thus the surface chemistry of carbon-based materials, which might be tailored by oxidizing agents and eventually affect the active phase on the catalyst, has been investigated by many authors.…”

“…Thus the surface chemistry of carbon-based materials, which might be tailored by oxidizing agents and eventually affect the active phase on the catalyst, has been investigated by many authors. 16,17,19 Thus the conception of adding carbon in tailoring surface of alumina as support seems an appealing practice in HDS catalysts.…”