Influence of Metal Deposition and Activation Method on the Structure and Performance of Carbon Nanotube Supported Palladium Catalysts

Abstract

The effects of the metal deposition and activation methods on metal particle size and distribution were investigated for carbon nanotube supported Pd catalysts. The Pd precursor was loaded by incipient wetness impregnation, ion adsorption, and deposition precipitation and was activated by thermal treatment under a nitrogen atmosphere or in the liquid phase by reduction by formaldehyde or sodium borohydride. Regardless of the metal precursor loading method, activation under a N2 atmosphere at 500 °C led to homogeneously distributed 4 nm Pd particles. Liquid‐phase reduction by sodium borohydride provided a bimodal distribution with particle sizes of approximately 1 and >10 nm. A somewhat weaker reducing agent, formaldehyde, yielded particles approximately 1 nm in size. The activities of the catalysts for the hydrogenation of cinnamaldehyde correlated with the particle sizes.

An Experimental and Theoretical Investigation on the Oxidation of CO over Pd/C Derived from the Spent Pd Catalyst

“…This may be due to the strong reducing behaviour of NaBH 4 which leads to the immediate reduction of metal precursor, forming larger particles. Similar observation was reported by Lamme et al [23] . for the Pd/CNT catalysts with particle size of up to 50 nm.…”

The Effect of Functional Group Polarity in Palladium Immobilized Multiwalled Carbon Nanotube Catalysis: Application in Carbon-Carbon Coupling Reaction

“…Hybrid structures involving carbon nanotubes (CNTs) and metal nanoparticles (NM) combine the unique properties of both 1 . These have been used in gas and liquid phase catalysis as well as electro catalysis [2][3][4][5][6][7][8] . Several CNT-NM hybrids have shown excellent reactivity 9 , and different synthetic procedures have been used to immobilize Pt, Pd, Ru and Rh NPs and a Rh/Pd alloy on CNTs.…”

Carbon-Supported Copper for Gas-Phase Hydrogenation Catalysis

“…[22][23][24] For instance, carbon materials are applied as catalysts for the synthesis of phosgene and thionyl chloride, 25 removal of NOx and SOX pollutants from flue gas streams [26][27] and various oxidation reactions. [28][29] Examples of industrial applications of carbon as a support material include catalysts based on Ru for ammonia synthesis, and [30][31] Pd and Pt for various hydrogenation reactions, biomass conversion and fuel cell applications, [32][33][34] while carbon supports were also used in academic studies such as for catalysts based on NiMo in hydrodesulphurization reactions, [35][36] and Fe and Co for Fischer Tropsch synthesis. [37][38][39] Metal oxides are typically preferred over carbon supports in terms of catalyst processing, shaping and stability at elevated temperatures in atmospheres containing O2 or H2 However, carbon provide several distinct advantages [22][23][24]40 such as high chemical resistance towards acids and bases, facile recovery of supported precious metals by combustion, and tunable structure, surface area and surface chemistry, as explained in the following paragraphs.…”

“…71,[75][76] Electrostatic adsorption of metal ions from a precursor solution is a well-known synthesis route to obtain high dispersions of precious metals, such as Pd and Pt. 34,[77][78] The support is suspended in a large excess of precursor solution. The pH of the solution is adjusted with respect to the point of zero charge of the surface, to introduce an electrostatic interaction between the oppositely charged metal precursor and support material.…”