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Activated carbon surface passivation method

A technology of activated carbon and inert gas, which is applied in the field of removing oxygen-containing functional groups on the surface of activated carbon, which can solve the problems of activated carbon adsorption performance degradation, pore structure change, and activated carbon specific surface area decrease, and achieve the effect of low comprehensive cost

Inactive Publication Date: 2011-04-06
SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the most common way to eliminate oxygen-containing functional groups on the surface of activated carbon is to heat treat in an inert atmosphere such as N2 or Ar gas at a high temperature above 800 °C or in a reducing atmosphere such as H2 to remove more than 90% of the surface of activated carbon However, after such a high temperature treatment, the specific surface area of ​​activated carbon will show a large decrease, and the pore structure will also change significantly, which will eventually lead to the deterioration of the adsorption performance of activated carbon.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Put 1Kg of spherical activated carbon into the reactor, feed 2000L / h. of N2, raise the temperature from room temperature to 400°C at a rate of 1°C / min, and stay for 0.5h; then cool to room temperature in an inert atmosphere, take out the activated carbon, According to the ratio of 1KgAC: 3 liters of hydrazine hydrate of 70wt% (unit): 1KgNaOH: 3 liters of diethylene glycol to prepare a mixture, and after heating from room temperature to 150°C, stay for 2h to evaporate excess hydrazine and water, and then Further raise the temperature to 190°C, stay for 3 hours, then cool down to room temperature, filter, wash, and dry to obtain surface-passivated activated carbon. The oxygen-containing functional groups on the surface of activated carbon before passivation are 2mg / mol, and the specific surface area is 848m2 / g. After passivation, the surface oxygen-containing functional groups and specific surface area are 0.12mg / mol and 842m2 / g, respectively.

Embodiment 2

[0017] Put 1Kg of granular activated carbon into the reactor, pass through 5000L / h. of N2, raise the temperature from room temperature to 450°C at a rate of 3°C / min, and stay for 1h; then cool to room temperature in an inert atmosphere, take out the activated carbon, press 1KgAC: 2 liters of 75wt% hydrazine hydrate: 3KgNaOH: 5 liters of diethylene glycol to prepare a mixture, and after heating from room temperature to 150°C, stay for 3h to evaporate excess hydrazine and water, and then further heat up to 190 °C, stay for 4 hours, then cool down to room temperature, filter, wash, and dry to obtain surface-passivated activated carbon. The oxygen-containing functional groups on the surface of activated carbon before passivation are 2.3mg / mol, and the specific surface area is 1032m2 / g. After passivation, the surface oxygen-containing functional groups and specific surface area are 0.22mg / mol and 1034m2 / g, respectively.

Embodiment 3

[0019] Put 1Kg of 200-mesh powdered activated carbon into the reactor, feed 8000L / h of Ar, raise the temperature from room temperature to 500 °C at a rate of 5 °C / min, and stay for 2 hours; then cool to room temperature in an inert atmosphere, take out the activated carbon, According to the ratio of 1KgAC: 2 liters of 80wt% hydrazine hydrate: 2KgNaOH: 4 liters of diethylene glycol, the mixture is formulated into a mixture, and after heating from room temperature to 150°C, it stays for 3 hours to evaporate excess hydrazine and water, and then further heats up to Stay at 190°C for 5 hours, then cool down to room temperature, filter, wash, and dry to obtain surface-passivated activated carbon. The oxygen-containing functional groups on the surface of activated carbon before passivation are 1.9mg / mol, and the specific surface area is 2052m2 / g. After passivation, the surface oxygen-containing functional groups and specific surface area are 0.13mg / mol and 2060m2 / g, respectively.

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Abstract

An activated carbon surface passivation method includes that: an activated carbon is placed into a reactor, 2-10L inert gas per gram activated carbon is led into the reactor in one hour, and the temperature is heated up from room temperature to 400-500 DEG C at a speed of 1-10 DEG C per minute and remains for 0.5-2h; the reactor is cooled to room temperature in inert gas, the activated carbon is taken out, the activated carbon, hydrazine hydrate and diethylene are prepared into mixed solution by the ratio of 1kg activated carbon, 1-3L 70-85% of hydrazine hydrate, 1-3kg NaOH and 3-5L diethylene glycol, the temperature is heated up from room temperature to 150-180 DEG C and remains for 2-3h, excessive hydrazine and water are steamed out, the temperature is further heated up to 190-220 DEG Cand remains for 3-5h and then is reduced to room temperature, and filtering, washing and drying are carried out, thus obtaining the activated carbon with passivated surface. The invention has the advantages of no change of specific area of the activated carbon during surface passivation and low comprehensive cost.

Description

technical field [0001] The invention provides a method for passivating the surface of activated carbon, specifically a method for removing oxygen-containing functional groups on the surface of activated carbon. Background technique [0002] Since activated carbon is obtained by reacting carbon-containing precursors with some oxygen-containing activators such as water vapor, CO2, or KOH at high temperature, the surface of activated carbon inevitably contains some oxygen-containing functional groups. When these activated carbons with oxygen-containing functional groups on the surface are used for the adsorption of petroleum substances, due to the interaction between oxygen-containing functional groups and some low-level hydrocarbons, a large amount of heat is generated, which increases the risk of petroleum products catching fire. The oxygen-containing functional groups on the surface of activated carbon are removed to passivate the surface. [0003] At present, the most comm...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B31/08
Inventor 李开喜刘植昌
Owner SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI