CN1128479C - Tin dioxide-base nanometer crystal gas-sensitive material and its preparation - Google Patents

Abstract

The present invention relates to a method for preparing tin dioxide nanometer crystal and tin dioxide thick film-base methane gas sensitive material. Ultra-fine micropowder of Al2O3 and SiO2 and a palladium catalyst are proportionally added in tin tetrachloride solution with specific pH value range, and hydrothermal chemical reaction and activating treatment are carried out at the temperature of more than 100 DEG C; thereby, the tin dioxide nanometer crystal composite powder of the present invention is obtained, is presintered at the temperature of 300 to 500 DEG C, and is prepared into slurry coated on carriers; the carriers coated with the slurry are processed through heat treatment at the temperature of 500 to 700 DEG C, so a gas sensor having high sensitivity and good selectivity on methane gas can be obtained.

Description

The preparation method who contains tin dioxide nanocrystal powder and tin dioxide thick film methane sensitive material

The invention relates to the preparation method of tin dioxide nanocrystal and tin dioxide thick film methane sensitive material, relate to a kind of tin ash (SnO ₂) nanocrystalline composite granule and SnO thereof ₂Base thick film methane (CH ₄) preparation method of gas sensitive.

Make SnO at present ₂Base CH ₄Gas sensitive, with chemical coprecipitation or sol-gal process, its major defect is SnO usually ₂Crystal grain crystallinity, surface activity and batch homogeneity are relatively poor, thereby to CH ₄Gas sensitivity is lower than same concentration ethanol (C ₂H ₅OH) carbon monoxide (CO) and hydrogen (H ₂) sensitivity, long-time stability are restricted.

The objective of the invention is to overcome above-mentioned two kinds of methods and prepare SnO ₂Nanocrystalline and SnO ₂Base thick film CH ₄The shortcoming of gas sensitive, it is good to study a kind of direct acquisition crystallinity, and crystallite dimension is 7～20nm, to CH ₄The thick film sensitive material preparation method of gas sensitization.It is characterized in that:

1. with ultrafine powder Al ₂O ₃, SiO ₂Being scattered in pH value by butter of tin percentage by weight 1～2%, 1～4%, 0.5～1% respectively with the catalyst of palladium is in 4～6 the butter of tin solution;

This solution is placed autoclave, add organic dispersing agent, hydrothermal chemical reaction and activation processing are 6～24 hours under the overcritical or subcritical state of the pressure of 5～10Mpa and 120～250 ℃, naturally cool to room temperature;

Promptly contain tin dioxide nanocrystal through washing, Separation of Solid and Liquid and dried powder.

2. with ultrafine powder Al ₂O ₃, SiO ₂Being scattered in pH value by butter of tin percentage by weight 1～2%, 1～4%, 0.5～1% respectively with the catalyst of palladium is in 4～6 the butter of tin solution;

This solution is placed autoclave, add organic dispersing agent, hydrothermal chemical reaction and activation processing are 6～24 hours under the overcritical or subcritical state of the pressure of 5～10Mpa and 120～250 ℃, naturally cool to room temperature;

To after placing 450～600 ℃ of pre-burnings, washing, Separation of Solid and Liquid and dried powder make thick film ink;

Then with this slurry coating on carrier with gold electrode, 600～700 ℃ of heat treatments 1～3 hour, promptly obtain CH ₄Have susceptibility height, thick film sensitive material that selectivity is good.

Claims (2)

1. contain the preparation method of tin dioxide nanocrystal powder, it is characterized in that:

With ultrafine powder Al ₂O ₃, SiO ₂Being scattered in pH value by 1～2%, 1～4%, 0.5～1% of butter of tin percentage by weight respectively with the catalyst of palladium is in 4～6 the butter of tin solution;

This solution is placed autoclave, add organic dispersing agent, hydrothermal chemical reaction and activation processing are 6～24 hours under the overcritical or subcritical state of the pressure of 5～10Mpa and 120～250 ℃, naturally cool to room temperature;

Promptly contain tin dioxide nanocrystal through washing, Separation of Solid and Liquid and dried powder.

2. the preparation method of tin dioxide thick film methane sensitive material is characterized in that:

With ultrafine powder Al ₂O ₃, SiO ₂Being scattered in pH value by butter of tin percentage by weight 1～2%, 1～4%, 0.5～1% respectively with the catalyst of palladium is in 4～6 the butter of tin solution;

This solution is placed autoclave, add organic dispersing agent, hydrothermal chemical reaction and activation processing are 6～24 hours under the overcritical or subcritical state of the pressure of 5～10Mpa and 120～250 ℃, naturally cool to room temperature;

To after placing 450～600 ℃ of pre-burnings, washing, Separation of Solid and Liquid and dried powder make thick film ink;

Then with this slurry coating on carrier with gold electrode, 600～700 ℃ of heat treatments 1～3 hour, promptly obtain thick film sensitive material to the methane gas sensitivity.