Method for preparing highly nitrogen-doped mesoporous carbon composites

Patent metadata

Field	Value
Publication number	US-10682633-B2
Application number	US-201615545536-A
Country	US
Kind code	B2
Filing date	Jan 21, 2016
Priority date	Jan 21, 2015
Publication date	Jun 16, 2020
Grant date	Jun 16, 2020

Abstract

Some embodiments are directed to a new methodology aimed at preparing highly N-doped mesoporous carbon macroscopic composites, and their use as highly efficient heterogeneous metal-free catalysts in a number of industrially relevant catalytic transformations.

First claim

The invention claimed is:

1. A method of preparing macroscopic composites made of a macroscopic support coated with a thin layer of highly nitrogen-doped mesoporous carbon phase, said method comprising:
(a) providing an aqueous solution of (i) (NH 4 ) 2 CO 3 ; (ii) a carbohydrate as carbon source, selected from aldose monosaccharides and glycosilated forms thereof, disaccharides and oligosaccharides or dextrine deriving from biomass conversion, and (iii) a carboxylic acid source selected from citric acid, and any other mono-, di-, tri-, and poly-carboxylic acid or their ammonium mono-, di-, tri- and poly-basic forms;
(b) providing a macroscopic support made of carbon-, silicon- or aluminum-based material, or binary mixtures thereof; wherein the macroscopic support is a single object or an assembly of smaller objects, wherein the overall dimension of the support ranges from 0.1 μm to 100 cm in three orthogonal directions;
optionally subjecting the maccroscopic support of step (b) to a passivation process comprising steps of:
(a1) providing an aqueous solution of citric acid and a carbohydrate as carbon source, selected from aldose monosaccharides and glycosilated forms thereof, disaccharides and oligosaccharides;
(b1) prior to step (c), immerging/soaking or impregnating the macroscopic support of step (b) in the aqueous solution of step (a1) for a suitable amount of time;
(c1) optionally removing the immerged macroscopic support from the aqueous solution of step (a1) if an excess aqueous solution is used in step (b1);
(d1) optionally subjecting the resulting macroscopic support to a gentle thermal treatment under air at low temperatures from 45 to 55° C.;
(e1) subjecting the resulting macroscopic support to a first thermal treatment under air at moderate temperatures from 110-150° C.±5° C.; and
(f1) subjecting the thermally treated macroscopic support to a second thermal treatment under inert atmosphere at higher temperatures from 600-800° C.±10° C.; thereby generating a macroscopic composite coated with a carbon layer;

(c) immerging/soaking or impregnating the macroscopic support of step (b), or the passivated macroscopic support obtained in step (f1) when a passivation process is used, in the aqueous solution of step (a) for a suitable amount of time;
(d) optionally removing the immerged macroscopic support from the aqueous solution of step (a) if an excess aqueous solution is used in step (c);
(e′) optionally subjecting the resulting macroscopic support to a gentle thermal treatment under air at low temperatures from 45 to 55° C.;
(e) subjecting the resulting macroscopic support to a first thermal treatment under air at moderate temperatures from 110-150° C.±5° C.;
(f) optionally subjecting the thermally treated macroscopic support to a second thermal treatment under air at higher temperatures:
from 400-500° C.±10° C., or
at 300° C.±10° C. for 2 to 4 hours;

thereby generating a macroscopic composite composed of a macroscopic support coated with a 20-200 nm thick layer of highly N-doped mesoporous carbonaceous material; wherein the N atom % in the mesoporous carbonaceous material is 25-40%; and
(g) optionally subjecting the macroscopic composite obtained in step (e) or (f) to a third thermal treatment by heating it to a temperature ranging between 600 to 900° C.±10° C. under inert atmosphere;
thereby generating a macroscopic composite composed of a macroscopic support coated with a 10-100 nm thick layer of highly N-doped mesoporous carbonaceous material; wherein the N atom % in the mesoporous carbonaceous material is 2-35%;
wherein the method comprises at least one of steps (f) or (g).

2. The method of claim 1 , wherein steps (c) through (f) are performed a first time and then repeated at least once prior to carrying out step (g).

3. The method of claim 1 , wherein in the aqueous solution of step (a), (NH 4 ) 2 CO 3 is present at a concentration ranging 1 to 8 mol/L; the carbohydrate carbon source is present at a concentration ranging from 1 to 5 mol/L; and the carboxylic acid source is present at a concentration ranging from 1 to 3 mol/L.

4. The method of claim 1 , wherein the macroscopic support is made of a material selected from β-SiC or α-SiC or SiC-based supports, either pure or doped with foreign elements including TiO 2 or SiO 2 , Al 2 O 3 , alumina, either pure or doped with foreign elements including TiO 2 or SiO 2 ; or carbon, each of which may be in the form of grains, flakes, rings, pellets, extrudates, beads or foam; or carbon nanotubes, carbon nanofibers, graphene or few-layer graphene.

5. The method of claim 1 , wherein the macroscopic support is made of silica (SiO 2 ), SiC, alumina (Al 2 O 3 ) or titania (TiO 2 ).

6. The method of claim 1 , wherein the macroscopic support is made of silica (SiO 2 ), alumina (Al 2 O 3 ) or titania (TiO 2 ), the method further comprising the passivation process.

7. The method of claim 1 , wherein the immerging/soaking or impregnating step (c) is carried out for 1 to 10 minutes.

8. The method of claim 1 , wherein the first thermal treatment step (e) is carried out for 1 to 10 hours.

9. The method of claim 1 , wherein the second thermal treatment step (f) is carried out for 1 to 10 hours.

10. The method of claim 1 , wherein the third thermal treatment step (g) is carried out for 1 to 10 hours.

11. The method of claim 1 , wherein the N-doped carbonaceous material layer:
has an N atom contents of 1-40%;
has an average pore size of 2-50 nm; and
has a thickness of 5 to 200±5 nm.

Assignees

• Univ Strasbourg
• Centre Nat Rech Scient
• Consiglio Nazionale Ricerche

Inventors

• Pham-Huu Cuong
• Giambastiani Giuliano
• Liu Yuefeng
• Ba Housseinou
• Nguyen-Dinh Lam
• Nhut Jean-Mario
• Duong-Viet Cuong

Classifications

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J2235/05

  Nuclear magnetic resonance [NMR] · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J35/50

  characterised by their shape or configuration · CPC title

• Y02E60/50

  Fuel cells · CPC title