Carbon Nanofibers Uniformly Grown on γ‐Alumina Washcoated Cordierite Monoliths

Abstract

A uniform layer of carbon nanofibers is grown on a cordierite monolith by first coating the monolith with a thin layer of γ‐alumina. The nanofibers form a thick, uniform layer on the monolith walls as shown in the figure, leading to the formation of a mesoporous and mechanically robust composite. The absence of microporosity in the composite and the ability to tune the thickness of the nanofiber layer suggests that these nanofibers/monolith composites may be useful as catalyst supports for liquid‐phase catalytic reactions.

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

“…Also, a larger nickel particle size resulted in nanofiber growth outside of the monolith. To enable a better growth rate and uniform distribution of nanofibers, García-Bordeje' et al have suggested using a thin γ-alumina washcoating of approximately 0.1 µm [104,201].…”

“…It was concluded that sols prepared via pseudoboehmite with urea and nitric acid and hydrolysis of tri-sec-butoxide are most suitable for sol-gel alumina coating of monoliths [10]. A typical sol-gel method of coating involves dipping the monolith in a sol from pseudoboehmite, urea and 0.3 M nitric acid in a weight ratio of 2:1:5, followed by emptying the channels, drying and finally calcination [104]. Sol-gel coating may be advantageous over conventional colloidal coating of monoliths, due to a strong adherence to the monolith, as the alumina layer forms on the surface of the channels.…”

Catalytic ozonation of metolachlor under continuous operation using nanocarbon materials grown on a ceramic monolith

“…CNF were formed under a gas flow of ethane and hydrogen (50:50). The detailed preparation method is described elsewhere [40]. The specific monolith used for the experiments here described had a diameter of 22 mm and a height of 60 mm, with square channels of 1 mm diameter.…”

“…The growth of CNF on the surface of a ceramic monolith has already been reported in the literature [39,40], as well as the application of the system to catalysis, including catalytic ozonation [22,39].…”

Structured carbons as supports for hydrogenation hybrid catalysts prepared by the immobilization of a Rh diamine complex

“…In particular, the use of powdery CNFs leads to agglomeration problems and difficulty of filtration in slurry phase operation, and pressure drop in gas phase operation. These inconveniences can be prevented by the incorporation of carbon filaments into larger objects like, for example, ceramic monoliths [7,8], sintered metal fibres or a carbon felt [9]. Another alternative could be the development of membranes consisting of entangled carbon nanofibers of a few tens of nanometer diameter obtained by electrospinning of a polymer followed by pyrolysis at high temperature [10,11].…”