DEPOSITION OF H-2-PERMSELECTIVE SIO2-FILMS
DEPOSITION OF H-2-PERMSELECTIVE SIO2-FILMS
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DOI：
10.1016/0009-2509(89)85125-5
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发表时间：
1989-01-01
影响因子：
4.7
通讯作者：
NAM, SW
中科院分区：
文献类型：
--
作者：
GAVALAS, GR;MEGIRIS, CE;NAM, SW
SiH_4氧化在多孔Vycor管壁内沉积了非晶态的SiO_2薄膜，形成了相反的反应物几何结构：SiH_4通过管内，而O_2通过管外。这两种反应物反向扩散，在管壁内的狭窄前沿内反应，形成一层薄薄的二氧化硅薄膜。一旦气孔被堵塞，反应物就无法相互接触，反应就停止了。在450℃、SiH4和O2的0.1和0.33atm下，反应在15min内完成。据估计，二氧化硅薄膜的厚度约为0.1μ。H_2和N_2渗透速率的测量表明，SiO_2膜对H_2渗透具有很强的选择性。450℃下的H2：N2流量在2000~3000之间变化。600℃的热退火在一定程度上降低了这种选择性。在H2O蒸气存在下的热处理进一步降低了H_2的通量，增加了H_2的通量。氢的渗透被认为是通过激活的扩散机制发生的。讨论了这种透氢膜在平衡受限反应膜反应器中的应用。
Films of amorphous SiO2were deposited within the walls of porous Vycor tubes by SiH4oxidation in an opposing-reactants geometry: SiH4was passed inside the tube while O2was passed outside the tube. The two reactants diffused opposite to each other and reacted within a narrow front inside the tube wall to form a thin SiO2film. Once the pores were plugged the reactants could not reach each other and the reaction stopped. At 450°C and 0.1 and 0.33 atm of SiH4and O2, the reaction was complete within 15 min. The thickness of the SiO2film was estimated to be about 0.1 μ. Measurements of H2and N2permeation rates showed that the SiO2film was highly selective to H2permeation. The H2: N2flux at 450°C varied between 2000 and 3000. Thermal annealing at 600°C reduced somewhat that selectivity. Thermal annealing in the presence of H2O vapor decreased further the flux of H2and increased the flux of H2. Permeation of H2is believed to occur through an activated diffusion mechanism. Applications of such H2-permeable films to membrance reactors for equilibrium-limited reactions are discussed.