Synthesis of Conjunctive Zeolite-Activated Carbon Composite Adsorbent from Rice Hulls for Simultaneous Adsorption of CO2 and H2O

Okutani, Takeshi; Utsumi, Tomomi; Ohnishi, Mitsuru

doi:10.2514/6.2012-3429

Cited by 4 publications

(1 citation statement)

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“…The amorphous silica dispersing at a molecular level in the cuticle has high reactivity and large specific surface of more than 300 m 2 •g -1 [17]. The amorphous silica crystallized to cristobalite and a small amount of tridymite at the combustion temperature above 900°C due to K2O containing 0.4 wt% in the combustion ash [5].…”

Section: Introductionmentioning

confidence: 99%

Retention of amorphous silica in rice hulls at high temperatures

Okutani¹

2020

J Met Mater Miner

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Rice hulls contains around 20 wt% amorphous silica (rice hull silica). Rice hull silica containing no potassium impurity crystallized from amorphous silica to cristobalite at 1300 Â°C. When a small amount of MgO or a-Fe2O3 or Al2O3 were added to the rice hull silica, the rice hull silica crystallized to cristobalite at 1500Â°C. MgO a-Fe2O3 and Al2O3 diffused to silica as Mg2+, Fe3+ and Al3+ at high temperatures. These ions broke the SiO4 tetrahedron network, so that the amorphous state of rice hull silica was maintained. As sintering occurred at 1500Â°C in rice hull silica mixed with additives such as MgO, the melting of the silica particle surface by sintering made the SiO4 tetrahedrons to move easily, so that the rearrangement of SiO4 tetrahedrons occurred and amorphous silica in the rice hull silica crystallized to cristobalite at 1500Â°C.

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Section: Introductionmentioning

confidence: 99%