Method for preparing supported catalysts from metal loaded carbon nanotubes

Abstract

A new method for preparing a supported catalyst is herein provided. Carbon nanotubes are functionalized by contacting them with an oxidizing agent to form functionalized carbon nanotubes. A metal catalyst is then loaded or deposited onto the functionalized carbon nanotubes. The mixture is then extruded to form the supported catalyst comprising a carbon nanotube structure containing metal catalyst more evenly dispersed within the internal structure of the carbon nanotube structure.

Description

CROSS REFERENCE INFORMATION [0001] This application claims benefit to and priority of U.S. Provisional Application No. 60 / 628,469, filed Nov. 16, 2004, which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] The invention relates to a new method for preparing supported catalyst by predeposition of the catalyst or catalyst precursor onto the carbon nanotube followed by formation of a carbon nanotube structure with the predeposited or metal loaded carbon nanotube. The result is a supported catalyst comprising a carbon nanotube structure with metal catalysts more evenly and thoroughly dispersed in the structure. As such, the supported catalyst of the present invention contains a higher concentration and better distribution of metal catalysts, leading to more efficient and higher yields of the desired final product. BACKGROUND OF THE INVENTION Supported Catalysts [0003] Supported catalysts (i.e., catalysts which are supported on some sort of surface, stru...

AI Technical Summary

Benefits of technology

[0032] Preferably, the carbon nanotube structure is a rigid porous structure formed by extruding the metal loaded carbon nanotubes. The metal loaded rigid porous structure may be further calcined to improve structural integrity.

[0033] Alternatively, the structure may be an assemblage formed by filtering a suspension of metal loaded carbon nanotubes. These conveniently take the form of thin mats especially useful in electrocatalysis. The metal loaded assemblage may be further calcined to improve structural integrity.

Problems solved by technology

Because heterogeneous reactions are normally carried out at elevated temperatures (and sometimes at elevated pressures as well) and in a reactive atmosphere, the exact chemical nature of the active catalyst component within the reaction zone can be difficult to determine.

These pores can be inaccessible because of diffusion limitations.

The cost of replacing attritted catalyst, the cost of separating it from the reaction mixture and the risk of contaminating the product are all burdens upon the process.

In slurry phase, e.g., where the solid supported catalyst is filtered from the process stream and recycled to the reaction zone, the attritted fines may plug the filters and disrupt the process.

In the case of a catalyst support, this is even more important since the support is a potential source of contamination both to the catalyst it supports and to the chemical process.

Further, some catalysts are particularly sensitive to contamination that can either promote unwanted competing reactions, i.e., affect its selectivity, or render the catalyst ineffective, i.e., “poison” it.

Carbons of natural resources may contain these materials as well as metals common to biological systems and may be undesirable for that reason.

Furthermore, supported catalysts which have catalytic materials more evenly dispersed throughout or within the support generally have higher yield and catalytic activity than supported catalysts which have poor distribution of the catalytic material in or on the support.

These differences, among others, make graphite and carbon black poor predictors of carbon nanotube chemistry.

While activated charcoals and other materials have been used as catalysts and catalyst supports, none have heretofore had all of the requisite qualities of high surface area, porosity, pore size distribution, resistance to attrition and purity for the conduct of a variety of selected petrochemical and refining processes as compared to carbon nanotube structures.

Furthermore, unlike carbon nanotube structures, much of the surface area in activated charcoals and other materials is in the form of inaccessible micropores.

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