The enhancement of direct amide synthesis reaction rate over TiO 2 @SiO 2 @NiFe 2 O 4 magnetic catalysts in the continuous flow under radiofrequency heating

Abstract

2017) The enhancement of direct amide synthesis reaction rate over TiO 2 @SiO 2 @NiFe 2 O 4 magnetic catalysts in the continuous flow under radiofrequency heating. Journal of Catalysis, 355. pp. 120-130. Permanent WRAP URL:Abstract A series of TiO2@SiO2@NiFe2O4 composite magnetic catalyst with a core-double shell structure was synthesized by a sol-gel method. The morphology of the catalysts was studied by XRD, SEM, N2 physisorption and their magnetic properties were examined with magnetometry, and specific absorption rate measurements. The catalytic activity was determined in a direct amide synthesis reaction between aniline and phenylbutyric acid at 150 o C in a fixed bed flow reactor under radiofrequency heating. The intermediate silica layer of the catalyst increased the porosity of the outer titania layer and the specific absorbance rate of the catalyst. The initial reaction rate increased by 61% as compared to a 2 similar core-shell TiO2@NiFe2O4 catalyst showing the detrimental effect of nickel ferrite ontitania. The reaction rate was further increased by a factor of 3.5 after a sulfation treatment due to an optimum Lewis acid site strength. The highest specific reaction rate over TiO2@SiO2@NiFe2O4 was observed at a 7.5 wt.% sulfate loading which was 2.6 times higher as compared to a mechanical mixture of the same composition. The initial reaction rate decreased by 36% after a period of 55 hours on stream. The catalyst activity was restored after a treatment with a H2O2 solution.

Engineering Iron–Nickel Nanoparticles for Magnetically Induced CO2Methanation in Continuous Flow

“…The target temperature is reached within few seconds and the energy is directly transferred inside the material without the need for heating the whole reactor system. This technology appeared first as an engineer solution for fast heating catalytic reactors, making use either of the walls of the reactor or from heating elements embedded inside, such as iron balls or ferrite microparticles . We have demonstrated the possibility to magnetically induce CO 2 methanation in a continuous‐flow reactor using core–shell NPs consisting of Ni or Ru coated iron carbide cores displaying high heating properties .…”

“…This technology appeared first as an engineer solution for fast heating catalytic reactors, making use either of the walls of the reactor [10][11][12] or from heating elements embedded inside, such as iron balls or ferrite microparticles. [1,13,14] We have demonstrated the possibility to magnetically induce CO 2 methanation in a continuous-flow reactor using core-shell NPs consisting of Ni or Ru coated iron carbide cores displaying high heating properties. [2,4] However, a modest CO 2 conversion (50 %) was achieved with a CH 4 yield of 15 %.…”

“…[22] The quasi instantaneous nature of magnetic heating seems well-adapted to the storage of intermittent energy, a promising solution being CO 2 methanation. [23][24][25] A large variety of catalysts has been investigated (Ni, Ru, Fe, Rh), [12,13] but Ni based catalysts are the most largely employed because of their high performance and low cost. [23] It has however previously been proposed through DFT calculations that Fe-Ni catalysts are more active than monometallic catalysts for CO 2 methanation since they combine good CO adsorption and CO dissociation.…”

Intraparticle Modeling of Non-Uniform Active Phase Distribution Catalyst

“…In the catalytic aromatization of methyl cyclopentane an increase in the conversion was observed when the metallic sites are distributed on the external surface of the particle [18]; egg-shell catalysts are also widely used in the hydrogenation of pyrolysis gasoline [19], ammonia decomposition [5], and the purification of automobile exhaust gases [20,21]. Recently, core-shell and core-double-shell catalysts have been compared in terms of amide production in reactors heated under radiofrequencies (RF), demonstrating that the reaction rates are increased by using an intermediate non-magnetic support layer [22].…”

Synthesis of a highly active amino‐functionalized Fe3O4@SiO2/APTS/Ru magnetic nanocomposite catalyst for hydrogenation reactions

“…More recently, magnetic core–shell nanocomposites have been widely used as supports for metal nanoparticles . Composites with magnetic cores and functional shell structures have received particular attention because the magnetic cores allow the composites to be conveniently collected or separated using an external magnet . Functional shells, such as SiO 2 and C, can be applied to immobilize metal nanoparticles .…”