Korean Chemical Engineering Research, Vol.46, No.3, 545-549, June, 2008
졸 합성시 숙성이 γ-Al2O3 입자의 표면특성에 미치는 영향
Effects of Surface Characterization of γ-Al2O3 Particles by Aging in the Sol Preparation
γ-AlO(OH) 졸 입자 뿐만 아니라 소성처리된 γ-Al2O3 입자의 표면특성을 γ-AlO(OH) 졸 제조시 숙성단계에 의하여 조절하였다. 연구결과, γ-AlO(OH) 졸 입자의 등전점은 숙성 증가에 따라 pH 9.25에서 pH 8.70까지 감소하였으며 γ-Al2O3 입자의 경우는 pH 9.90에서 pH 8.86까지 감소하였다. 숙성에 따른 γ-Al2O3 입자의 산, 염기 특성을 고찰한 결과, γ-Al2O3 입자의 산량은 숙성시간의 증가에 따라 0.1367 mmol/g에서 0.0783 mmol/g까지 감소하였으며, Hammett 산성도함수 Ho는 4.8 이상의 산세기를 보였다. 한편 γ-Al2O3 입자의 염기량은 숙성시간의 증가에 따라 0.4399 mmol/g에서 0.3074 mmol/g 까지 감소하였다. 따라서 졸-겔법에 의한 γ-Al2O3 제조시 숙성공정이 산, 염기점의 양을 포함한 표면특성을 조절할 수 있는 중요 공정변수임을 제시하였다.
The surface characteristics of calcined γ-Al2O3 particles as well as γ-AlO(OH) sol particles were controlled by aging in the boehmite sol preparation. As a result of the study, the IEPs of γ-AlO(OH) particles were decreased from pH 9.25 to pH 8.70 and those of the calcined γ-Al2O3 particles were decreased from pH 9.90 to pH 8.86 by the increase of the aging times. As a result of the acidic and basic characterization of the calcined γ-Al2O3 particles by the aging, the amount of acid sites was decreased from 0.1367 mmol/g to 0.0783 mmol/g by the increase of the aging times and Hammett acidity, Ho was showed the acidic strength of 4.8 or above. On the other hand, the amount of basic sites was decreased from 0.4399 mmol/g to 0.3074 mmol/g by the increase of the aging times. Based on these results, we proposed the fact that the aging step in the sol-gel process was an important step to control the surface characterization of γ-Al2O3 particles including acidity and basicity.
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