Microwave-Assisted Hydrogen Transfer to Anthracene and Phenanthrene over Pd/C

Abstract

Microwave-assisted hydrogen transfer to anthracene and phenanthrene over Pd/C was investigated under mild conditions. The effects of reaction temperature, initial hydrogen pressure, and reaction time on the reactant conversions and product selectivities were examined. The results show that the hydrogenations of both reactants proceed at much lower temperature and hydrogen pressure under microwave irradiation than those by conventional heating and that related reactions include both mon-and biatomic hydrogen transfer. The reactivities of both reactants and their products toward hydrogenation and/or dehydrogenation are closely related to superdelocalizability and resonance energy values of the related species.

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

“…However, better hydrogen transfer properties of the carbon-based catalyst cannot be ruled out. A metal-free AC was shown to be effective in hydrogen transfer to anthracene [11], which is indicative of the fact that carbon supports may promote monoatomic hydrogen transfer, as stated in [12]. The amount of coke deposited on the catalysts was significantly lower for the FCNF-supported ones (0.047 and 0.081 g coke •g cat -1 , compared to 0.284 g coke •g cat -1 for NiMo/Al 2 O 3, as observed in Table 3).…”

“…In addition, some studies indicated higher hydrodesulfurisation (HDS), hydrodenitrogenation (HDN) and hydrodemetallisation (HDM) activity of carbon-supported catalysts compared to those supported on Al 2 O 3 , as reviewed in [10]. This higher activity was attributed to a more efficient activation of metal sites and transfer of hydrogen to reactant molecules [11,12]. Additionally, the lower metal-support interaction compared to typical acid supports such as alumina and zeolites makes a larger fraction of active phase available to the reactants.…”

Microwave‐Assisted Cross‐Coupling and Hydrogenation Chemistry by Using Heterogeneous Transition‐Metal Catalysts: An Evaluation of the Role of Selective Catalyst Heating

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18] Literature examples include the utilization of Pd/C, [5][6][7] Pd/SiO 2 , [8] PdEnCat, [9] Pd/glass, [10,11] supported/stabilized Pd nanoparticles, [12] Ni/C, [13] Ni/graphite, [14] Cu/C, [15] and other supported metal species [16] in combination with microwave dielectric heating for achieving highly efficient carbon-carbon and carbonheteroatom bond formation reactions. In addition, several cases of microwave-enhanced hydrogenation reactions involving Pd/C and related supported metal species have been reported.…”

“…In addition, several cases of microwave-enhanced hydrogenation reactions involving Pd/C and related supported metal species have been reported. [17,18] However, the selective heating of metal (or other strongly microwave absorbing) particles under microwave conditions is a rather complex phenomenon depending strongly on the type of support, particle size (surface-to-volume ratio), electromagnetic field strength (power density), and a variety of other factors. [4,19] In heterogeneous gas-phase catalysis, the rationale and advantages of using microwave irradiation to selectively heat the often very strongly microwave absorbing catalyst bed while the reactive gas-being inherently microwave transparent-remains at a lower temperature are reasonably well established.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18] In the present manuscript, we present a critical reinvestigation of microwave-heated transitionmetal-catalyzed carbon-carbon/carbon-heteroatom crosscoupling reactions and hydrogenation protocols, to elucidate the role that microwave irradiation in conjunction with the use of heterogeneous catalysts plays in these transformations.…”