Study on extraction of silica from rice husk by sol-gel method and its application in catalytic decomposition of methane

In order to solve the pollution problem of agricultural waste and realize the harmlessness, reduction and resource of abandoned rice husk, silica was successfully extracted from rice husk by sol-gel method and used for methane decomposition to produce hydrogen. The effects of reaction temperature and mass fraction of sodium carbonate on the yield of silica were studied. When the reaction temperature was 120 degrees C and Na2CO3 was 9 wt.%, the yield of silica was 52.3%. The effects of acid on the pyrolysis behavior of rice husk and the purity and the specific surface area of derived silica were investigated. The results showed that the thermal stability of rice husk and the purity of SiO2 were improved after acid pretreatment. Compared with the silica sample prepared without acid pretreatment (4.7m(2)/g), the specific surface area of the silicon dioxide pretreated by HAc (SiO2-HAc) increased to 27m(2)/g. Rice husk-derived silica was used as a catalyst to produce hydrogen from methane decomposition, SiO2-HAc showed good catalytic activity, and the conversion of methane increased from 17.01% to 38.83%. This change was attributed to the formation of -Si-C- species, which promoted the decomposition of methane. On this basis, Ni/SiO2-HCl and Ni/SiO2-HAc catalysts were prepared by loading metal Ni on the surface of rice husk-derived silica, and the conversion of methane increased to 74.33% and 60.73%, respectively.

Automated summary

In this study, silica was successfully extracted from rice husk using the sol-gel method and used for methane decomposition to produce hydrogen. Acid pretreatment improved the thermal stability of rice husk and the purity of silica. Rice husk-derived silica showed good catalytic activity in methane decomposition, increasing the conversion of methane.