Preparation method for walnut shell active carbon adsorbent for purifying low concentration phosphine

Abstract

The present invention discloses a preparation method for a walnut shell active carbon adsorbent for purifying low concentration phosphine. According to the preparation method, a walnut shell raw material is subjected to treatments of crushing, washing and drying; the treated walnut shells are placed in a tube type furnace to carry out carbonization for 1 hour at a certain temperature under protection of nitrogen to obtain a carbonized material; the carbonized material is uniformly mixed with an activator potassium hydroxide according to a certain ratio; the resulting mixture is place in the tube type furnace to carry out activation for 1 hour at a certain temperature under protection of nitrogen; the walnut shells are washed by hydrochloric acid, and rinsed by hot distilled water until the pH value of the walnut shells is neutral, then the walnut shells are dried to obtain the walnut shell active carbon; the walnut shell active carbon is subjected to a metal supported modification treatment, wherein metal active components comprise copper, zinc and lanthanum; then treatments of ultrasonic impregnation, drying and baking are performed to prepare the walnut shell active carbon adsorbent. The walnut shell active carbon adsorbent is characterized in that: with adopting the walnut shell active carbon adsorbent to treat the waste gas containing the phosphine, advantages of high purification efficiency, large adsorption capacity, low cost and the like are provided; the development of the adsorbent provides a simple and feasible approach for comprehensive utilization of the agricultural and forestry waste walnut shells and purification of the phosphine waste gas.

Description

technical field [0001] The invention relates to a walnut shell activated carbon adsorbent for purifying low-concentration phosphine and a preparation method thereof, belonging to the technical field of material preparation technology applied to air pollution purification. technical background [0002] Phosphine is present in certain concentrations in the gases produced in processes such as yellow phosphorus preparation, magnesium powder preparation, sodium hypophosphite production, acetylene production, feed fermentation, grain fumigation, and semiconductor industry production. Direct discharge of phosphine in the exhaust gas into the atmosphere will cause environmental pollution and endanger human health. If the phosphine-containing tail gas, especially the yellow phosphorus tail gas rich in CO, is utilized, the catalyst will be poisoned by the presence of phosphine, which seriously restricts the resource utilization of waste. Phosphine is included in the US EPA's list of ...

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Problems solved by technology

[0005] The oxidation-reduction absorption method uses the reducing property of phosphine to react with a solution containing an oxidant (such as sodium hypochlorite, potassium permanganate, concentrated sulfuric acid, hydrogen peroxide, phosphoric acid, etc.) to purify phosphine. Consumption of oxidant, dephosphorization efficiency is closely related to oxidant concentration, and the concentration of oxidant drops rapidly during the absorption reaction, so there are disadvantages such as high operating cost, easy fluctuation of dephosphorization efficiency, and poor operability of the device

Chinese patent CN 85105317 (publication number) reports a method for washing phosphine from acetylene gas. This method uses 70% phosphoric acid solution, but the process is complicated, and the gas needs to be pretreated by a milk of lime scrubber. The scrubbing acid is regenerated with pure oxygen and no mention is made of the residual concentration of phosphine after scrubbing

Considering that the adsorption capacity of blank activated carbon for phosphine is poor, in order to improve the adsorption effect of activated carbon for phosphine, the researchers modified activated carbon by acid-base modification, vulcanization modification and metal modification. Generally speaking, the adsorption capacity of activated carbon adsorbents for phosphine is small. The saturated adsorption capacity of activated carbon adsorbents prepared in previous studies for phosphine is only about 140mg / g. Therefore, the development of adsorption capacity for phosphine Larger activated carbon adsorbent becomes the key content of the present invention

In recent years, the preparation of activated carbon from agricultural and forestry wastes has attracted the attention of many researchers, but the use of activated carbon prepared from walnut shells from agricultural and forestry wastes to purify low-concentration phosphine has not been reported.

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