Dehydrogenation Of Benzylamine Research Articles

Synergetic Effect of B and O Dopants for Aerobic Oxidative Coupling of Amines to Imines

Boron-doped mesoporous carbon material (B–C) was fabricated by annealing boric acid and sustainable cellulose at high temperature in inert atmosphere. This heteroatom-doped carbon exhibited excellent catalytic activity and high selectivity in the oxidative coupling of amine to imines. Owing to the recyclable utilization of boric acid involved in the preparation of B–C and a kind of earth abundant natural biomass being the carbon source, this metal-free carbon catalyst could be regarded as a kind of green and sustainable catalyst. Characterizations, such as X-ray photoelectron spectroscopy and X-ray absorption near edge structure, demonstrated that boron mainly existed in the form of CBO2 and functioned as catalytic active site. A proposed catalytic mechanism based on density functional theory calculations pointed out that synergistic effect of B and O atoms in CBO2 promoted adsorption and dehydrogenation of benzylamine. The intermediators, such as hydrogen peroxide, ammonia, and phenylmethanimine, could b...

Ruthenium Dioxide Catalysts for the Selective Oxidation of Benzylamine to Benzonitrile: Investigating the Effect of Ruthenium Loading on Physical and Catalytic Properties

The oxidative dehydrogenation of benzylamine to benzonitrile was studied in batch and continuous flow processes using ruthenium dioxide catalysts with varying ruthenium loadings. Increased conversions were observed in the continuous flow process compared with the batch process (up to 100% in the flow process compared with up to 92% in the batch process), with increased selectivity to benzonitrile (82 and 65%, respectively) and benzonitrile yields (84 and 58%, respectively). The major by-product was N-benzylidenebenzylamine. The ruthenium loading in the catalyst was successfully optimised and the most active catalyst had a ruthenium loading of 2.5–3.5 wt%.

Catalytic Hydrogen Production by Ruthenium Complexes from the Conversion of Primary Amines to Nitriles: Potential Application as a Liquid Organic Hydrogen Carrier.

The potential application of the primary amine/nitrile pair as a liquid organic hydrogen carrier (LOHC) has been evaluated. Ruthenium complexes of formula [(p-cym)Ru(NHC)Cl2 ] (NHC=N-heterocyclic carbene) catalyze the acceptorless dehydrogenation of primary amines to nitriles with the formation of molecular hydrogen. Notably, the reaction proceeds without any external additive, under air, and under mild reaction conditions. The catalytic properties of a ruthenium complex supported on the surface of graphene have been explored for reutilization purposes. The ruthenium-supported catalyst is active for at least 10 runs without any apparent loss of activity. The results obtained in terms of catalytic activity, stability, and recyclability are encouraging for the potential application of the amine/nitrile pair as a LOHC. The main challenge in the dehydrogenation of benzylamines is the selectivity control, such as avoiding the formation of imine byproducts due to transamination reactions. Herein, selectivity has been achieved by using long-chain primary amines such as dodecylamine. Mechanistic studies have been performed to rationalize the key factors involved in the activity and selectivity of the catalysts in the dehydrogenation of amines. The experimental results suggest that the catalyst resting state contains a coordinated amine.

Utilization of Active Ni to Fabricate Pt-Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation.

Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel-aluminum layered double hydroxide (NiAl-LDH) onto a Pt-Ni alloy surface. The incorporation of chemical etching of Pt-Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni-rich Pt-Ni octahedra transform by interior erosion into Pt3 Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3 Ni, the resulting Pt-Ni nanoframe/NiAl-LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural.

Liquid-Phase Deamination of Benzylamine and m-Xylylenediamine in the Presence of Nickel Catalysts.

The Kinetics of liquid-phase deamination of benzylamine and m-xylylenediaminein the presence of nickel catalysts was studied under the flow of nitrogen at 15°C.The results obtained by using benzylamine agreed well with the rate equationbased upon the Langmuir-Hinshelwood mechanism, the ratio of adsorption equilibrium constant for benzylidene benzylamine to that for benzylamine being 9.3. Itwas suggested that the reaction involved two parallel routes : (1) dehydrogenation of benzylamine, and (2) hydrogen transfer reaction between benzylamine and benzylidene benzylamine. At low conversion of benzylamine, benzylidene benzylaminewas predominantly formed by the former route and at high conversion, benzylidenebenzylamine and dibenzylamine were formed by the latter route. The reactivity of m-xylylenediamine was almost comparable to that of benzylamine. It seemed that the condensate of m-xylylendiamine consisted of its trimer and high polymers.