US-12617684-B2 - Catalyst support, and method of producing fibrous carbon nanostructure

Abstract

The purpose of the present invention is to provide a catalyst support with which it is possible to produce a high-quality fibrous carbon nanostructure. The purpose of the present invention is to provide a catalyst support used when producing a fibrous carbon nanostructure, the catalyst support comprising a carrier and a catalyst layer formed on the carrier, the catalyst layer including a metal-containing compound, and the difference ΔYI in yellowness expressed by the formula being 3-20, where YI A is the yellowness of the carrier, and YI B is the yellowness of the catalyst support. ΔYI=YI B −YI A .

Inventors

• Yusuke Ono

Assignees

• ZEON CORPORATION

Dates

Publication Date

20260505

Application Date

20220113

Priority Date

20210128

Claims (7)

1. 1 . A method of producing catalyst supports for use in producing fibrous carbon nanostructures, the catalyst supports comprising: carriers and a catalyst layer formed on the carriers, wherein the catalyst layer comprises a metal-containing compound, and wherein the method comprises a step of adjusting a difference ΔYI in yellowness expressed by the formula ΔYI=YI B −YI A to be 3 or more and 20 or less, where YI A is a yellowness of the carriers, and YI B is a yellowness of the catalyst supports.
2. 2 . The method of producing catalyst supports according to claim 1 , wherein the metal-containing compound comprises an iron compound.
3. 3 . The method of producing catalyst supports according to claim 2 , wherein the iron compound comprises an iron oxide.
4. 4 . The method of producing catalyst supports according to claim 1 , wherein the carriers have a surface covered with a catalyst supporting layer.
5. 5 . The method of producing catalyst supports according to claim 4 , wherein the catalyst supporting layer comprises a ceramic material.
6. 6 . The method of producing catalyst supports according to claim 5 , wherein the ceramic material comprises an aluminum oxide.
7. 7 . A method of producing fibrous carbon nanostructures, comprising a step of supplying a source gas to the catalyst supports produced by the method of producing catalyst supports according to claim 1 to synthesize fibrous carbon nanostructures on the catalyst layer.

Description

TECHNICAL FIELD This disclosure relates to catalyst supports, and a method of producing fibrous carbon nanostructures. BACKGROUND Fibrous carbon nanostructures such as carbon nanotubes (hereinafter, also referred to as “CNTs”, see for example, Non-patent Literature (NPL) 1) are used in a wide variety of applications as being excellent in various characteristics such as mechanical strength, sliding property, flexibility, semi- and metallic conductivity, and thermal conductivity, as well as being high in chemical stability. In light thereof, in recent years, studies have been made on methods of producing, efficiently and at low cost, fibrous carbon nanostructures having such excellent characteristics. Here, as the methods of producing carbon nanotubes, arc discharge methods, laser evaporation methods, chemical vapor deposition (CVD) methods, and other methods are reported. Of those methods, CVD methods are suited for large-scale synthesis, continuous synthesis, and highly pure synthesis of single-walled carbon nanotubes excellent in the aforementioned characteristics, and various studies are being made thereon (see, for example, NPL 2). CVD methods use catalyst supports obtained by supporting a catalyst component on surfaces of substrates or particles serving as carriers. For example, Patent Literature (PTL) 1 discloses technology of synthesizing carbon nanotubes on a support on which a catalyst including Fe and other elements is supported, by flowing a source gas consisting of acetylene, carbon dioxide, and an inert gas at predetermined partial pressures over the support. Further, PTL 2 discloses a fluidized bed method for synthesizing carbon nanotubes by using catalyst supports obtained by forming a catalyst layer on a surface of particulate carriers. CITATION LIST Patent Literature PTL1: WO2012/057229APTL 2: JP2020-157229A Non-Patent Literature NPL 1: S. Iijima, Nature 354, 56 (1991).NPL 2: “Fundamentals and Applications of Carbon Nanotubes” co-edited with Riichiro Saito and Hisanori Shinohara, pp. 33 to 34, Baifukan, 2004 SUMMARY Technical Problem However, fibrous carbon nanostructures produced by using the aforementioned conventional s still have room for improvement in terms of quality such as, for example, specific surface area. Accordingly, it could be helpful to provide catalyst supports capable of producing high-quality fibrous carbon nanostructures. It could also be helpful to provide a method of producing fibrous carbon nanostructures capable of producing high-quality fibrous carbon nanostructures. Solution to Problem The inventor conducted diligent investigation to achieve the objectives set forth above. Through this investigation, the inventor has found that, when catalyst supports obtained by forming a catalyst layer including a metal-containing compound on carriers have a difference in yellowness falling within a predetermine range, the difference being obtained by subtracting the yellowness of the carriers from the yellowness of the catalyst supports, high-quality fibrous carbon nanostructures can be produced using said catalyst supports, to thereby complete the disclosure. That is, this disclosure aims to advantageously solve the problems set forth above, and the catalyst supports disclosed herein are catalyst supports for use in producing fibrous carbon nanostructures, the catalyst supports including carriers and a catalyst layer formed on the carriers, in which the catalyst layer includes a metal-containing compound, and the difference ΔYI in yellowness expressed by the formula ΔYI=YIB−YIA being 3 or more and 20 or less, where YIA is the yellowness of the carriers and YIB is the yellowness of the catalyst supports. In this manner, when catalyst supports obtained by forming a catalyst layer including a metal-containing compound on carriers have a difference in yellowness falling within a predetermined range, the difference being obtained by subtracting the yellowness of the carriers from the yellowness of the catalyst supports, high-quality fibrous carbon nanostructures can be produced using said catalyst supports. The yellowness YIA of the carriers and the yellowness YIB of the catalyst supports can be measured by the method described in Examples disclosed herein. Here, in the catalyst supports disclosed herein, in a case where the surface of the carriers is covered with a catalyst supporting layer to be described later, the term “carrier” refers to a carrier in a state of being covered with the catalyst supporting layer. That is, in the catalyst supports disclosed herein, when catalyst supporting layer-attached carriers obtained by covering a surface of the carriers with the catalyst supporting layer, the “yellowness YIA of the carrier” refers to the yellowness YI obtained by measuring the catalyst supporting layer-attached carriers by the method described in Examples disclosed herein. Further, in this disclosure, fibrous carbon nanostructures including carbon nanotubes can be regarded as