Catalyst for preparing phosgene and method for preparing phosgene using the same

Patent metadata

Field	Value
Publication number	US-9399582-B2
Application number	US-201414904138-A
Country	US
Kind code	B2
Filing date	Feb 11, 2014
Priority date	Aug 26, 2013
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

The present invention relates to a catalyst for preparing phosgene and a method for preparing phosgene using the catalyst. Said method comprises: modifying the surface of an activated carbon coating/foamed silicon carbide structural catalyst using an alkali metal salt; filling the catalysts having different thickness of the activated carbon coating and different amount of the alkali metal salt in different sections in the axial direction of the multi-tubular reactor of the fixed bed, and preparing phosgene using Cl 2 and CO. The radial and axial temperature difference of the catalyst bed is lowered by using the alkali metal salt-modified activated carbon coating/foamed silicon carbide structural catalyst and by segmental filling, so that high temperature of tube wall is obtained in the case of a larger tube diameter, and high quality of steam is obtained stably.

First claim

The invention claimed is:

1. A catalyst for preparing phosgene, wherein said catalyst is an alkali metal salt-modified activated carbon coating/foamed silicon carbide structural catalyst, and the activated carbon coating has the thickness of 0˜800 μm, preferably 0.1 ˜300 μm.

2. The catalyst according to claim 1 , wherein: the amount of said alkali metal salt is 0.01˜100 g/L, preferably 0.3˜30 g/L, based on the volume of the catalyst.

3. The catalyst according to claim 2 , wherein: said alkali metal salt is one or more selected from chlorides, nitrates and sulfates, preferably sodium chloride and/or potassium chloride.

4. A method for preparing the catalyst of claim 1 , wherein: immersing the activated carbon coating/foamed silicon carbide structural catalyst in 0.5˜2 mol/L, preferably 0.8˜1.5 mol/L of the aqueous solution of the alkali metal salt, taking the catalyst out and drying; calcining the dried catalyst at 400˜500° C. for 1˜2 hours under nitrogen atmosphere, thereby obtaining the alkali metal salt-modified activated carbon coating/foamed silicon carbide structural catalyst.

5. A method for preparing phosgene by using the catalyst of claim 1 or the catalyst obtained by the method of claim 4 , wherein: carbon monoxide and chlorine gas are reacted in the multi-tubular reactor of a fixed bed packed with the catalyst, wherein the catalyst is packed in the multi-tubular reactor of the fixed bed in section, thus divides the multi-tubular reactor of the fixed bed, from bottom to top of the reactor in the axial direction of it, as: a reaction initiation section (1), a rapid reaction section (2), a smooth transition section (3), and an outlet temperature decreasing section (4);
wherein,
the length of said reaction initiation section (1) is 10˜20% of the total length of the tube(s), and in the reaction initiation section (1), the thickness of the activated carbon coating is 0˜300 μm, preferably 50˜200 μm, and the amount of the alkali metal salt is 0.1˜5 g/L, preferably 0.3˜1 g/L, based on the volume of the catalyst;
the length of said rapid reaction section (2) is 10˜20% of the total length of the tube(s), and in the rapid reaction section (2), the thickness of the activated carbon coating is 0˜100 μm, preferably 0˜50 μm, and the amount of the alkali metal salt is 10˜30 g/L, preferably 20˜30 g/L, based on the volume of the catalyst;
the length of said smooth transition section (3) is 40˜50% of the total length of the tube(s), and in the smooth transition section (3), the thickness of the activated carbon coating is 50˜300 μm, preferably 100˜200 μm, and the amount of the alkali metal salt is 5˜20 g/L, preferably 5˜15 g/L, based on the volume of the catalyst;
the length of said outlet temperature decreasing section (4) is 20˜30% of the total length of the tube(s), and in the outlet temperature decreasing section (4), the thickness of the activated carbon coating is 0˜300 μm, preferably 50˜100 μm, and the amount of the alkali metal salt is 0.5˜10 g/L, preferably 1˜5 g/L, based on the volume of the catalyst.

6. The method according to claim 5 , wherein: the volume ratio of carbon monoxide and chlorine gas is 1˜1.05:1.

7. The method according to claim 5 , wherein: the reaction pressure is 0˜0.4 MPa, preferably 0.1˜0.35 MPa.

8. The method according to claim 5 , wherein: the heat transfer medium of the multi-tubular reactor of the fixed bed is boiling water, carbon tetrachloride, chlorobenzene, ortho-dichlorobenzene or toluene, preferably boiling water.

9. The method according to claim 5 , wherein: the radial temperature difference in the multi-tubular reactor of the fixed bed is <200° C., the temperature of the hot spot is <500° C., the height of the part having the reaction temperature in the range of 400˜500° C. in the axial direction of the tube(s) is 40% or more of the total axial height of the tube(s), and the height of the part having the reaction temperature in the range of 250˜500° C. in the axial direction of the tube(s) is 90% or more of the total axial height of the tube(s).

Assignees

• Wanhua Chemical Group Co Ltd
• Wanhua Chemical (Ningbo) Co Ltd

Inventors

• Chen Bin
• Luo Wuxi
• Yao Yu
• Shao Liangfeng
• Wang Lei
• Zhang Hongke
• Hua Weiqi

Classifications

• B01J35/40

  characterised by dimensions, e.g. grain size (in a colloidal state B01J35/23; crystallite size B01J35/77) · CPC title

• B01J21/18 Primary

  Carbon · CPC title

• B01J27/224

  Silicon carbide · CPC title

• B01J37/08

  Heat treatment {(B01J37/0009, B01J37/0018 take precedence)} · CPC title

• B01J35/023

  Operations & Transport · mapped topic