One kind of transition metal / nitrogen co-doped carbon composite material for removal of formaldehyde and its preparation

Abstract

This invention discloses one kind of co-doped carbon composite material with transition metal and nitrogen for removal of formaldehyde and its preparation method. The materials are composed of non-noble metals as active components and nitrogen-doped carbon carrier; The non-noble metal active components are transition metal salts of nickel, cobalt, iron and manganese or their mixtures. The carbon composite materials reported in this invention have high specific surface area and strong adsorption and catalytic decomposition performance for formaldehyde, and harsh conditions (e.g. high reaction temperature etc.) are not required for catalytic oxidation of formaldehyde. It also features in low cost, high catalytic efficiency at room temperature and long durability etc.

Claims

1. The distinguishing feature of one kind of transition metal/nitrogen co-doped carbon composite for the removal of formaldehyde is that it consists of non-noble metal active components and nitrogen-doped carbon carrier. The non-noble metal active components are transition metal salts.

2. According to claim 1, wherein the transition metals in the co-doped carbon composite materials for the removal of formaldehyde are the salts of nickel, cobalt, iron, manganese or their mixture.

3. According to claim 1, the preparation method for the transition metal/nitrogen co-doped carbon composite material for the removal of formaldehyde includes the following steps: (1) solution of transition metal salts were mixed with nitrogen-containing organic matter solution, and the mixture was heated with stirring to obtain precursors of transition metals; (2) the co-doped carbon composite material was prepared by calcinating the precursors in an inert atmosphere after washing and vacuum drying.

4. According to claim 3, wherein the transition metal precursors were prepared from aqueous solution of one or more transition metal salts of nitrate, chloride, acetate and sulfate.

5. According to claim 3, wherein the nitrogen-containing organic substance is an imidazole or urea derivative.

6. According to claim 3, wherein the mass ratio for the transition metal salt:the nitrogen-containing organic matter:water is from 1:1˜100:200˜1000.

7. According to claim 3, wherein the reaction temperature for the transition metal salt and the nitrogen-containing organic matter is from 0 to 100° C., and the reaction time is from 1 to 36 hours.

8. According to the method in claim 3, wherein nitrogen, helium, or argon has been employed for the inert atmosphere.

9. According to the method in claim 3, wherein the calcination temperature is 300-900° C., and the calcination time is from 1 to 36 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 The TEM image of the precursor of Example 1;

[0017] FIG. 2 The TEM image of the catalyst obtained after calcination of Example 2.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The non-noble metal catalyst for formaldehyde removal and the preparation method according to the present invention will be further described with some specific embodiments. The specific embodiments are intended to describe the present invention in further details rather than limiting scope of the invention. Unless stated, the methods and materials used in this invention are commonly used in this field.

Example 1 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0019] 0.45 g cobalt nitrate, 5 g dimethylimidazole and 50 ml water were mixed, heated and stirred at 40° C. for 10 h, and then washed and vacuum dried. The prepared solid powder was calcined at 300° C. for 4 h under N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 2 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0020] 0.9 g cobalt nitrate, 11 g dimethylimidazole and 100 ml water were mixed, stirred at 60° C. for 30 h, washed with methanol and vacuum dried. The prepared solid powder was calcined at 500° C. for 5 h in Ar atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 3 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0021] 0.9 g cobalt nitrate, 16 g dimethylimidazole and 150 ml water were mixed, heated and stirred at 70° C. for 2 h, and then washed and vacuum dried. The prepared solid powder was calcined at 600° C. for 6 h in N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 4 Preparation of Transition Metal and Nitrogen Co-Doped Carbon Composites

[0022] 0.9 g cobalt nitrate, 20 g dimethylimidazole and 200 ml water were mixed, and stirred at 50° C. for 8 h, followed by washing and vacuum drying. The prepared solid powder was calcined at 600° C. for 6 h in air atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 5 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0023] 0.9 g nickel nitrate, 11 g dimethylimidazole and 100 ml water were mixed and stirred at 70° C. for 2 h, followed by washing and vacuum drying. The prepared solid powder was calcined at 600° C. for 8 h under N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 6 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0024] 0.9 g iron nitrate, 20 g dimethylimidazole and 150 ml water were mixed, heated and stirred at 80° C. for 2 h, and then washed and vacuum dried. The prepared solid powder was calcined at 700° C. for 10 h under N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 7 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0025] 0.9 g manganese chloride solid, 20 g dimethylimidazole and 150 ml water were mixed, heated and stirred at 80° C. for 2 h, and then washed and vacuum dried. The prepared solid powder was calcined at 700° C. for 10 h under N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 8 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0026] 0.9 g cerium nitrate, 20 g dimethylimidazole and 150 ml water were mixed, heated and stirred at 90° C. for 4 h, and then washed and vacuum dried. The prepared solid powder was calcined at 700° C. for 10 h in N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 9 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0027] 0.9 g nickel sulfate, 20 g dimethylimidazole and 150 ml water were mixed, heated and stirred at 80° C. for 2 h, and then washed and vacuum dried. The prepared solid powder was calcined at 700° C. for 10 h in N2 atmosphere to obtain a transition metal/nitrogen co-doped carbon composite.

Example 10 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0028] 0.5 g Co(NO3)2 solid, 0.5 g of Ni(NO3)2 and 11 g 2-methylimidazole were dissolved in 60 mL deionized water, stirred at 40° C. for 5 h, then washed and dried at 80° C. for 14 h. The prepared solid powder was calcined at 600° C. for 5 h in N2 atmosphere to obtain the final product.

Example 11 Preparation of Transition Metal/Nitrogen Co-Doped Carbon Composites

[0029] 0.7 g Co(NO3)2, 0.2 g FeCl2 and 6 g 2-methylimidazole solid were dissolved in 70 mL deionized water, stirred at 70° C. for 3 h, and then washed and dried at 75° C. for 18 h. The obtained solid powder was calcined at 450° C. for 6 h in N2 atmosphere to obtain the final product.

Comparative Example 1

[0030] 0.9 g cerium nitrate, 4 g urea and 150 ml water were mixed, stirred at 60° C. for 10 h, then washed and vacuum dried. The prepared solid powder was calcined at 700° C. for 10 h to obtain a catalyst.

[0031] 200 mg of the catalyst prepared in the above examples and comparative examples were respectively placed in a tubular fixed bed reactor for experimentation with the following experimental conditions: room temperature (˜30° C.), oxygen 20%, nitrogen 80%. Formaldehyde gas is bubbled, and blown into the reaction system by nitrogen gas. The formaldehyde concentration of the reactor inlet was 50 mg/m3, and the gas hourly space velocity (GHSV) is 30000 ml g−1 h−1. The results of the activity evaluation are shown in Table 1.

TABLE-US-00001 TABLE 1 Activity evaluation results of transition metal and nitrogen co-doped carbon composites Room Temperature Formaldehyde Sample Conversion Rate (%) Example 1 50.4 Example 2 95.7 Example 3 60.1 Example 4 81.3 Example 5 58.6 Example 6 37.9 Example 7 34.2 Example 8 45.8 Example 9 47.1 Example 10 96.7 Example 11 86.1 Comparative 1 15.1

[0032] It can be seen from Table 1 that with the preparation method and under conditions of the present invention, the catalytic formaldehyde removal performance of the prepared transition metal/nitrogen co-doped carbon composite material is significantly improved comparing with the comparative example.