KR100401763B1 - A nonstoichiometric Titanium dioxide with photocatalytic effect and the method - Google Patents
A nonstoichiometric Titanium dioxide with photocatalytic effect and the method Download PDFInfo
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- KR100401763B1 KR100401763B1 KR10-2001-0036301A KR20010036301A KR100401763B1 KR 100401763 B1 KR100401763 B1 KR 100401763B1 KR 20010036301 A KR20010036301 A KR 20010036301A KR 100401763 B1 KR100401763 B1 KR 100401763B1
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- titanium dioxide
- transition metal
- quantitative
- amorphous
- photocatalytic
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims abstract description 159
- 239000004408 titanium dioxide Substances 0.000 title claims abstract description 75
- 230000001699 photocatalysis Effects 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims description 13
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 52
- 150000003624 transition metals Chemical class 0.000 claims abstract description 52
- 230000007547 defect Effects 0.000 claims abstract description 34
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000001301 oxygen Substances 0.000 claims abstract description 27
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 27
- 206010021143 Hypoxia Diseases 0.000 claims abstract description 16
- 239000010936 titanium Substances 0.000 claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 claims abstract description 11
- 239000007789 gas Substances 0.000 claims abstract description 8
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000000843 powder Substances 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 9
- 230000007704 transition Effects 0.000 claims description 9
- 239000011941 photocatalyst Substances 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 150000003839 salts Chemical class 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- 239000002243 precursor Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000012153 distilled water Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 3
- -1 M (NO 3 ) X Chemical class 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 150000003609 titanium compounds Chemical class 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 19
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 9
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 abstract description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 abstract description 4
- 230000008859 change Effects 0.000 abstract description 4
- 239000013078 crystal Substances 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 238000007254 oxidation reaction Methods 0.000 abstract description 3
- 230000002708 enhancing effect Effects 0.000 abstract description 2
- 238000000746 purification Methods 0.000 abstract description 2
- 230000009467 reduction Effects 0.000 abstract description 2
- 230000001976 improved effect Effects 0.000 abstract 1
- 230000001939 inductive effect Effects 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000001965 increasing effect Effects 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 239000010431 corundum Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000009283 thermal hydrolysis Methods 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000004887 air purification Methods 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 230000000843 anti-fungal effect Effects 0.000 description 1
- 229940121375 antifungal agent Drugs 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000009469 supplementation Effects 0.000 description 1
- 229910000348 titanium sulfate Inorganic materials 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- XLOMVQKBTHCTTD-UHFFFAOYSA-N zinc oxide Inorganic materials [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
- B01J21/063—Titanium; Oxides or hydroxides thereof
-
- B01J35/39—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0072—Preparation of particles, e.g. dispersion of droplets in an oil bath
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
Abstract
개시된 내용은 환원성 분위기를 통하여 정량 이산화티탄내의 산소결핍을 유발시켜 비정량 이산화티탄화하는 한편 전이금속을 첨가하여 결함을 배가함으로써 광촉매특성을 강화시킨 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄 및 그 제조방법에 관한 것이다.Disclosed non-quantitative titanium dioxide having a photocatalytic property which enhances the photocatalytic properties by inducing oxygen deficiency in the quantitative titanium dioxide through a reducing atmosphere and adding defects by adding a transition metal, thereby enhancing the photocatalytic properties. It relates to a manufacturing method.
이러한 본 발명의 비정량 이산화티탄(TiOy; y=1.152~1.992)은 결정구조를 그대로 유지한 채, 환원성 분위기내의 산소분압의 변화를 통하여 물질내부에 산소결핍에 의한 결함을 유발하여 광촉매특성을 개선한 효과를 갖는다. 더욱이, 본 발명의 비정량 이산화티탄, 특히 전이금속첨가 비정량 이산화티탄(Ti1-xMxOy; x=0~0.1, y=1.512~1.992)은 물질내부에 산소결핍에 의한 결함과 전이금속첨가에 따른 결함을 내포하고 있어서 그 결함레벨이 상승적으로 작용하여 그 효율이 매우 뛰어나다. 또한, 본 발명은 산소분압 및 전이금속첨가량을 변화시켜 일산화탄소의 산화반응이나 질소산화물의 환원반응에 최적합한 광촉매물질을 손쉽게 얻을 수 있어 자동차배기가스의 정화처리에 적용하여 뛰어난 효과를 볼 수 있을 것으로 기대된다.Such non-quantitative titanium dioxide (TiO y ; y = 1.152 ~ 1.992) of the present invention causes photocatalytic properties by causing defects due to oxygen deficiency in the material through the change of oxygen partial pressure in a reducing atmosphere while maintaining the crystal structure. It has an improved effect. Furthermore, the amorphous titanium dioxide of the present invention, in particular the transition metal addition amorphous titanium dioxide (Ti 1-x M x O y ; x = 0 ~ 0.1, y = 1.512 ~ 1.992) is characterized by defects caused by oxygen deficiency in the material. It contains defects due to the addition of transition metals, and its defect level acts synergistically, so the efficiency is very excellent. In addition, the present invention can easily obtain a photocatalytic material that is optimal for the oxidation reaction of carbon monoxide or the reduction of nitrogen oxides by changing the oxygen partial pressure and the amount of transition metal addition, it can be applied to the purification process of automobile exhaust gas can be seen an excellent effect It is expected.
Description
본 발명은 광촉매 효과를 발하는 비정량 이산화티탄에 관한 것으로, 특히 환원성 분위기를 통하여 정량 이산화티탄내의 산소결핍을 유발하여 비정량 이산화티탄화하고 전이금속을 첨가하여 결함레벨을 배가함으로써 광촉매특성을 강화시킨 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄 및 그 제조방법에 관한 것이다.The present invention relates to non-quantitative titanium dioxide having a photocatalytic effect. In particular, the present invention relates to non-quantitative titanium dioxide by causing oxygen deficiency in quantitative titanium dioxide through a reducing atmosphere, thereby enhancing photocatalytic properties by doubling the defect level by adding transition metals. The present invention relates to a transition metal addition amorphous titanium dioxide having a photocatalytic property and a method of manufacturing the same.
일반적으로, 광촉매 효과(Photocatalytic effect)란 광에너지를 흡수하여 높은 에너지상태가 된 다음, 그 에너지를 반응물질에 주어 물질의 분해와 같은 화학반응을 일으키는 작용을 말한다. 이러한 광촉매 효과는 항균, 항곰팡이, 공기정화작용, 대기오염물질인 질소산화물이나 유황산화물의 무해화, 폐수처리 등 다양한 분야에 적용이 가능하다. 이와 같은 광촉매 효과를 발하는 물질에는 ZnO, SiO2,TiO2등이 있는 데, 그 중에서도 특성면으로 볼 때 이산화티탄(TiO2)이 가장 적합한 물질로 여겨지고 있다.In general, the photocatalytic effect refers to the action of absorbing light energy into a high energy state and then giving that energy to the reactant to cause chemical reactions such as decomposition of the material. The photocatalytic effect can be applied to various fields such as antibacterial, antifungal, air purification, harmless nitrogen oxide or sulfur oxide, and wastewater treatment. Materials that exhibit such a photocatalytic effect include ZnO, SiO 2 , TiO 2 , and the like, and among them, titanium dioxide (TiO 2 ) is considered to be the most suitable material.
기존에는 이러한 광촉매 효과를 발하는 물질로 정량 이산화티탄이 사용되었고, 그 특성을 보완하기 위하여 추가적인 금속들의 치환을 이용하였다. 그러나, 그에 따른 광촉매 특성변화는 매우 미미한 실정이었다. 좀더 부연설명하면, 기존의 광촉매 물질은 정량 이산화티탄이 갖는 일정한 밴드갭(3.0~3.4eV)을 이용하거나, 전이금속계열을 첨가하여 물질내부에 첨가된 원소에 의한 결함을 생성하고, 그로 인한 밴드갭내의 결함레벨을 이용하여 광촉매 특성의 향상을 유도했었다. 하지만, 그러한 노력에도 불구하고 그 효율성이 매우 떨어져 광촉매특성이 좋지 않았다.In the past, quantitative titanium dioxide was used as a material for causing such a photocatalytic effect, and supplementation of additional metals was used to supplement its properties. However, the photocatalyst characteristic change was very small. More specifically, the conventional photocatalyst material uses a constant bandgap (3.0 to 3.4 eV) of quantitative titanium dioxide, or creates a defect due to an element added in the material by adding a transition metal series, resulting in a band The defect level in the gap was used to induce improvement in photocatalytic properties. However, despite such efforts, the efficiency was so poor that the photocatalytic properties were not good.
따라서, 본 발명의 목적은 상술한 제결점들을 해소하기 위해서 안출한 것으로서, 환원성 분위기내의 산소분압의 변화를 통하여 이산화티탄내의 산소결핍을 유발하여 밴드갭내의 결함을 발생시키는 한편 전이금속을 첨가하여 결함레벨을 배가시킴으로써 물질내부에 산소결핍에 의한 결함과 전이금속첨가에 따른 결함을 내포하여 광촉매특성의 향상을 가져온 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄을 제공하는 데 있다.Accordingly, an object of the present invention is to solve the above-mentioned drawbacks, the oxygen deficiency in titanium dioxide through the change of the partial pressure of oxygen in a reducing atmosphere to produce a defect in the band gap while adding a transition metal defect It is to provide a transition metal-added non-quantitative titanium dioxide having a photocatalytic property which includes a defect due to oxygen deficiency and a defect due to the addition of a transition metal in a material by doubling the level, thereby improving the photocatalytic properties.
또한, 본 발명의 다른 목적은 상기 전이금속첨가 비정량 이산화티탄을 제조하는 방법을 제공하는 데 있다.Another object of the present invention is to provide a method for preparing the transition metal addition amorphous titanium dioxide.
도 1은 본 발명에 따른 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄의 제조방법을 개략적으로 보여주는 흐름도.1 is a flow chart schematically showing a method for producing a transition metal-added amorphous titanium dioxide having a photocatalytic property according to the present invention.
위의 목적을 달성하기 위한 본 발명에 따른 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄은 광촉매효과를 갖는 이산화티탄에 있어서, 정량 이산화티탄이 강한 환원성 분위기에서 산소분압의 조절에 의해 산소결핍결함이 유발된 TiOy(y=1.152~1.992)의 조성을 갖는 것을 특징으로 한다. 더욱이, 상기 비정량 이산화티탄(TiOy)에 전이금속을 첨가하여 추가적인 결함을 얻은 Ti1-xMxOy(x=0~0.1, y=1.512~1.992)의 조성을 갖는 것을 특징으로 한다.In order to achieve the above object, the transition metal-added non-quantitative titanium dioxide having a photocatalytic property according to the present invention is a titanium dioxide having a photocatalytic effect, in which quantitative titanium dioxide is deficient in oxygen by controlling oxygen partial pressure in a strong reducing atmosphere. It is characterized by having a composition of the induced TiO y (y = 1.152 ~ 1.992). Further, it is characterized by having a composition of Ti 1-x M x O y (x = 0 to 0.1, y = 1.512 to 1.992) obtained by adding a transition metal to the non-quantitative titanium dioxide (TiO y ).
상기 다른 목적을 달성하기 위한 본 발명에 따른 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄제조방법은 증류수에 티탄화합물을 용해한 후 가열하여 전구체분말을 얻는 단계; 상기 전구체분말을 용액과 분리하고 세척건조하여 정량 비결정 이산화티탄분말을 제조하는 단계; 및 상기 비결정분말을 환원성 분위기에서 열처리하여 비정량 이산화티탄을 얻는 단계를 포함한다. 상기 열처리시 전이금속을 첨가하여 전이금속첨가 비정량 이산화티탄조성물(Ti1-xMxOy; x=0~0.1, y=1.512~1.992)을 얻는 단계를 더 포함한다.According to the present invention, there is provided a method of preparing a transition metal-added non-quantitative titanium dioxide having a photocatalyst property, the method comprising: obtaining a precursor powder by dissolving a titanium compound in distilled water and then heating it; Separating the precursor powder from the solution and washing and drying to prepare a quantitative amorphous titanium dioxide powder; And heat treating the amorphous powder in a reducing atmosphere to obtain amorphous titanium dioxide. Adding a transition metal during the heat treatment further includes obtaining a transition metal addition amorphous titanium dioxide composition (Ti 1-x M x O y ; x = 0 ~ 0.1, y = 1.512 ~ 1.992).
본 발명에서는 비정량 이산화티탄(TiOy, y=1.152~1.992)을 개발하여 별도의 원소추가 없이도 산소결핍에 의한 밴드갭내의 결함레벨을 발생시킬 수 있다. 뿐만 아니라, 여기에 추가적으로 전이금속계열 Fe,Cr,Co,Ni,Mn,Cu 등을 첨가하여 새로운 조성의 전이금속첨가 비정량 이산화티탄(Ti1-xMxOy)를 얻어 효율을 보다 개선하였다.여기서, M은 전이금속을 그리고, x=0~0.1, y=1.512~1.992이다. 이러한 전이금속첨가 비정량 이산화티탄은 물질 내부에 산소결핍에 의한 결함과 전이금속의 첨가에 따른 결함을 내포하고 있어서 광촉매효과가 크게 증진된다. 특히, 비정량 이산화티탄의 제조에 있어서 물질내의 산소결핍도, 즉 산소결핍에 의한 결함은 환원성 분위기 내의 산소분압을 변화시키면 가능하다. 또한, 전이금속첨가 비정량 이산화티탄의 경우에 전이금속과 티탄과의 비는 첨가비율을 조절함으로써 가능하다.In the present invention, by developing a non-quantitative titanium dioxide (TiO y , y = 1.152 ~ 1.992) it is possible to generate a defect level in the band gap due to oxygen deficiency without additional elements. In addition, the transition metal-based Fe, Cr, Co, Ni, Mn, Cu, etc. are added to this to obtain a transition metal additive non-quantitative titanium dioxide (Ti 1-x M x O y ) of a new composition to further improve efficiency Where M is a transition metal and x = 0 to 0.1 and y = 1.512 to 1.992. Such transition metal addition amorphous titanium dioxide contains defects due to oxygen deficiency and defects due to the addition of transition metal in the material, thereby greatly improving the photocatalytic effect. In particular, in the production of non-quantitative titanium dioxide, the degree of oxygen deficiency in the material, that is, defect due to oxygen deficiency, can be changed by changing the oxygen partial pressure in the reducing atmosphere. In addition, in the case of a transition metal addition amorphous titanium dioxide, the ratio of the transition metal to titanium can be adjusted by adjusting the addition ratio.
그럼, 먼저 정량 이산화티탄으로부터 비정량 이산화티탄을 제조하는 방법에 대해 상세하게 설명한다. 즉, 정량 이산화티탄의 제조법은 이미 널리 공지되어 있는 바, 이 정량 이산화티탄으로부터 비정량 이산화티탄을 얻는 방법에 대해 설명하기로 한다.First, a method for producing non-quantitative titanium dioxide from quantitative titanium dioxide will be described in detail. That is, since the method for producing quantitative titanium dioxide is well known, a method of obtaining non-quantitative titanium dioxide from the quantitative titanium dioxide will be described.
정량 이산화티탄을 환원성 분위기, 즉 산소분압이 낮은 대기내에 방치할 경우 일반적인 반응인 티탄금속의 산화반응의 역반응이 일어나게 된다. 이에 따라, 아래 반응식과 같이 정량 이산화티탄의 내부에서 산소의 방출이 있게 된다.When quantitative titanium dioxide is left in a reducing atmosphere, that is, an atmosphere having a low oxygen partial pressure, a reverse reaction of the oxidation reaction of titanium metal, which is a general reaction, occurs. Accordingly, there is an emission of oxygen inside the quantitative titanium dioxide as shown in the following reaction formula.
[반응식][Scheme]
Ox O ½O2+ Vo ¨+ 2e′O x O ½O 2 + V o ¨ + 2e ′
여기서, 윗첨자는 결함 또는 전하의 극성을 나타내며, 아래첨자는 결함의 위치를 나타낸다. 또한, ·은 +전하를, ′는 -전하를 의미하고, 아래첨자의 o는 물질내부결정 내의 산소자리를 의미한다.Here, the superscript indicates the polarity of the defect or charge, and the subscript indicates the position of the defect. In addition, · means + charge, ′ means – charge, and the subscript o means oxygen site in the internal crystal.
위의 반응은 대기 내의 산소분압이 낮을수록 많이 일어나게 되고, 그에 따라서 물질 내부의 산소공극(Vo)의 농도도 증가하게 된다. 이때, 산소분압은 10-30.1~10-25.7atm이 적당하다. 만약, 산소분압이 너무 낮을 경우에는 Ti2O3의 상이 형성된다. 이 Ti2O3는 정량 이산화티탄의 상인 루타일 또는 아나타제 상이 아닌 코룬덤 구조를 가지게 된다. 아나타제와 루타일은 비슷한 구조로서 그에 따른 밴드갭의 값(3.0~3.4eV)도 비슷한 반면, 코룬덤 구조는 밴드갭값이 8eV이상으로 광촉매물질로는 부적합하다. 또한, 산소분압이 너무 높을 경우에도 비정량 이산화티탄이 생성되기에 충분치 않아서 정량 이산화티탄이 얻어지게 된다. 이와 같이 비정량 이산화티탄을 얻기 위한 조건으로 위와 같은 적절한 산소분압이 요구되며, 산소결핍에 따른 결함농도, 즉 산소공극의 농도는 산소분압에 따라서 결정되므로 위의 산소분압에 의해 얻어지는 비정량 이산화티탄 내부의 산소공극의 농도는 2.3×1020~1.4×1022개/cm-3가 된다. 냉각 방법에 따라서도 산소공극의 농도 역시 변화하게 된다. 일반적으로 결함의 농도는 열역학 제2법칙에 의하여 온도가 올라갈수록 증가하게 된다. 따라서, 고온에서 열처리 후, 급랭(50??C/초~5??C/초)하게 된다면, 고온 상태의 결함농도를 그대로 또는 증가시킬 수 있게 된다. 증가하는 이유로서는 열전도에 의한 내부와 외부의 온도차로 열충격이 발생하게 되고, 그로 인한 입자 내의 결함 생성이 주 원인이다. 즉, 열처리 후 로냉할 경우, 상온의 평형 결함농도를 가지겠지만, 급랭 시엔 고온 상태의 결함농도 또는 그 이상의 농도를 유지할 수 있는 방법이 된다.The above reaction occurs as the oxygen partial pressure in the atmosphere is lowered, and accordingly, the concentration of oxygen voids (V o ) in the material increases. At this time, the oxygen partial pressure is appropriately 10 -30.1 ~ 10 -25.7 atm. If the oxygen partial pressure is too low, a phase of Ti 2 O 3 is formed. This Ti 2 O 3 has a corundum structure other than the rutile or anatase phase, which is a phase of quantitative titanium dioxide. Anatase and rutile have similar structures and similar bandgap values (3.0 to 3.4 eV), while corundum structures have a band gap value of 8 eV or more, which is unsuitable for photocatalytic materials. In addition, even when the oxygen partial pressure is too high, it is not enough to produce non-quantitative titanium dioxide, and thus quantitative titanium dioxide is obtained. As such, an appropriate oxygen partial pressure is required as a condition for obtaining non-quantitative titanium dioxide, and the concentration of defects due to oxygen deficiency, that is, the concentration of oxygen vacancies is determined according to the oxygen partial pressure. The concentration of the oxygen vacancies inside is 2.3 × 10 20 to 1.4 × 10 22 pieces / cm −3 . Depending on the cooling method, the concentration of oxygen pores also changes. In general, the concentration of defects increases with increasing temperature according to the second law of thermodynamics. Therefore, if the rapid cooling (50 ° C / sec ~ 5 ° C / sec) after the heat treatment at high temperature, it is possible to increase or increase the defect concentration in the high temperature state. The reason for the increase is that a thermal shock occurs due to a difference in temperature between the inside and the outside due to heat conduction, and the main cause is the generation of defects in the particles. That is, when the furnace is cooled by heat treatment, it will have an equilibrium defect concentration at room temperature, but it will be a method capable of maintaining a defect concentration at or above the high temperature state during quenching.
위와 같이 제조된 비정량 이산화티탄으로부터 전이금속첨가 이산화티탄을 얻는 방법에 대해 보다 상세하게 설명하면 다음과 같다.The method of obtaining transition metal-added titanium dioxide from the non-quantitative titanium dioxide prepared as described above will be described in more detail.
위에서 기설명한 바와 같이 제조된 비정량 이산화티탄의 조성에 전이금속계열을 첨가함으로써 전이금속첨가 비정량 이산화티탄 광촉매조성물(Ti1-xMxOy; x=0~0.1, y=1.512~1.992)을 얻을 수 있다. 여기서, M은 전이금속으로 Fe,Cr,Co,Ni,Mn,Cu등이 사용되는 데, 금속염의 형태나 산화물의 형태로 첨가 가능하다. 금속염으로는 M(NO3)X, MClX, M(acetate)X, M(CO3)X등이 그리고, 산화물형태로는 MOX이 사용될 수 있으며, 여기서 M은 전이금속을 나타낸다.Transition metal addition non-quantitative titanium dioxide photocatalyst composition (Ti 1-x M x O y ; x = 0 ~ 0.1, y = 1.512 ~ 1.992 by adding transition metal series to the composition of non-quantitative titanium dioxide prepared as described above ) Can be obtained. Here, M is used as a transition metal Fe, Cr, Co, Ni, Mn, Cu, etc., can be added in the form of metal salts or oxides. As the metal salt, M (NO 3 ) X , MCl X , M (acetate) X , M (CO 3 ) X , and the like, and MO X may be used as an oxide form, where M represents a transition metal.
비정량 이산화티탄의 광촉매특성을 향상하기 위해서 전이금속을 사용하는 이유는 전이금속은 산소결핍과 같은 결함에 의해서 쉽게 전자가가 변화될 수 있어 비정량 이산화티탄에서 생성된 산소공극을 상쇄하지 않고도 비정량 이산화티탄 내부에 치환 또는 첨가될 수 있기 때문이다.The reason why the transition metal is used to improve the photocatalytic properties of the amorphous titanium dioxide is that the transition metal can be easily changed due to defects such as oxygen deficiency. This is because it can be substituted or added inside the quantitative titanium dioxide.
본 발명에 사용되는 전이금속으로는 정량 이산화티탄이 가지는 전자가 +4가가 아닌 어떤 원소도 사용할 수 있으며, 첨가시 비정량 이산화티탄의 내부격자에서 티탄과 치환되어 티탄의 전자가와는 다른 전자가로 인해 전자가 발생되는 한편 첨가되어 물질 내부에 정공을 생성시키게 된다. 이러한 전이금속첨가에 의한 전자 및 정공은 광촉매특성의 향상에 기여하게 되고, 이들의 농도는 전이금속의 첨가량에 의해 결정된다.As the transition metal used in the present invention, any element other than +4 can be used as the electron of quantitative titanium dioxide, and when added, electrons different from the electron value of titanium are substituted with titanium in the internal lattice of non-quantitative titanium dioxide. As a result, electrons are generated and added to generate holes in the material. The electrons and holes due to the addition of the transition metal contribute to the improvement of the photocatalytic properties, and their concentration is determined by the amount of the transition metal added.
이하, 본 발명의 바람직한 실시예를 첨부된 도면에 의거하여 상세히 설명한다.Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
실시예Example
도 1은 본 발명에 따른 광촉매 특성을 가진 전이금속첨가 비정량 이산화티탄의 제조방법을 개략적으로 보여주는 흐름도로, 이제 이 도면을 참조하면서 본 발명의 제조방법에 대해 상세히 설명한다.1 is a flowchart schematically showing a method for producing a transition metal-added non-quantitative titanium dioxide having a photocatalytic property according to the present invention, which will now be described in detail with reference to this drawing.
증류수에 황산화티탄(TiOSO4) 1몰(M)을 첨가하고, 10℃ 이하에서 30분간 혼합하여 용액을 만들었다. 이때, 용해온도가 10℃보다 높을 경우에는 금속염이 충분히 용해되기 전에 석출되어 분말성상의 조절이 어렵고, 30분보다 적은 시간 혼합한 경우에는 염의 용해가 충분하지 않다. 염이 용해된 용액을 열가수분해공정을 통해 정량 이산화티탄 수하물로 제조하기 위하여, 위의 용액을 90℃에서 30분간 가열하여 전구체분말을 얻었다. 이때, 가열온도가 90℃보다 낮을 경우에는 석출되는 분말의 양이 적으며, 높을 경우에는 분말의 크기분포가 커진다.(단계 100)1 mole (M) of titanium sulfate (TiOSO 4 ) was added to distilled water, followed by mixing at 10 ° C. or lower for 30 minutes to form a solution. At this time, when the dissolution temperature is higher than 10 ° C, the metal salt is precipitated before being sufficiently dissolved, so that it is difficult to control the powder phase, and when the mixture is mixed for less than 30 minutes, the dissolution of the salt is not sufficient. In order to prepare a solution in which the salt is dissolved into quantitative titanium dioxide baggage through a thermal hydrolysis process, the above solution was heated at 90 ° C. for 30 minutes to obtain precursor powder. At this time, when the heating temperature is lower than 90 ° C, the amount of powder to be deposited is small, and when it is high, the size distribution of the powder is increased (step 100).
열가수분해 후, 원심분리기를 3000rpm으로 10분간 작동시켜 전구체분말과 용액을 분리시켰다. 이때, 분리된 분말을 증류수로 세척하고, 120℃에서 1시간동안 건조하여 정량 비결정 이산화티탄분말을 얻었다.(단계 110)After thermal hydrolysis, the centrifuge was operated at 3000 rpm for 10 minutes to separate the precursor powder and the solution. At this time, the separated powder was washed with distilled water and dried at 120 ℃ for 1 hour to obtain a quantitative amorphous titanium dioxide powder. (Step 110)
위에서 얻은 비결정분말을 그대로 열처리하면 비정량 이산화티탄이 얻어지고, 열처리시 비결정분말에 Fe,Cr,Co,Ni,Mn,Cu등의 전이금속을 첨가혼합하면 전이금속첨가 이산화티탄을 얻을 수 있다. 이때, 첨가되는 전이금속은 M(NO3)X, MClX,M(acetate)X, M(CO3)X등의 금속염이나 MOX등의 산화물의 형태로 첨가가 가능하다. 따라서, 위와 같은 전이금속물질을 비결정분말과 중량비 0~5%로 혼합한 다음, 이를 분위기로에 넣고 10-10~10-3atm까지 진공화하였다. 이때, 진공화정도가 낮은 경우 분위기 처리시 산소분압을 낮추기 어렵다. 그런 다음, 환원성 분위기의 분압이 10-2~1atm에 도달할 때까지 아르곤을 충전하였다. 이와 같은 환원성 분위기를 필요로 하는 이유는 비정량 이산화티탄을 얻기 위해서는 산소분압이 최소 10-25atm이 필요하므로, 이를 위해 진공화하는 방법보다는 환원성 기체를 사용하는 것이 바람직하기 때문이다. 이때 사용되는 환원성 기체로는 수소나 일산화탄소가 적합하며, 사용된 기체의 종류에 따라서 산소분압의 차이가 발생하게 된다. 또한, 같은 산소분압이라 하더라도 수소 및 일산화탄소를 분위기처리한 분말의 표면반응성에서도 차이가 나타난다. 위와 같이 아르곤을 충전하여 환원성 분위기의 분압이 대기압에 이르면, 환원성 기체를 채운 다음 분당 5℃의 속도로 증열하면서 400~750℃에서 0.5~4시간동안 열처리하였다. 이때, 열처리온도가 낮거나 시간이 짧은 경우에는 결정화반응이 충분하지 않게 되며, 온도가 높거나 시간이 길 경우에는 아나타제상이 아닌 루타일상을 얻게 된다. 일반적으로, 광촉매효과는 아나타제상이 우수하다고 보고되고 있는 바, 열처리온도와 시간을 위와 같이 조절하면 아나타제상을 얻게 된다. 그리고, 열처리 냉각 공정을 급랭또는 서랭함으로써, 고온 상태의 결함농도를 유지 또는 증가시킬 수 있다. 이와 같이, 환원성 분위기상에서의 열처리중에 비결정분말은 정량 이산화티탄에서 환원분위기에 의해 산소결핍된 비정량 이산화티탄으로 변이하였고, 전이금속물질이 첨가되어 전이금속첨가 비정량 이산화티탄이 얻어졌다.(단계 120)When the amorphous powder obtained above is heat-treated as it is, amorphous titanium dioxide is obtained, and transition metal addition titanium dioxide can be obtained by adding and mixing transition metals such as Fe, Cr, Co, Ni, Mn, and Cu to the amorphous powder during the heat treatment. In this case, the transition metal to be added may be added in the form of metal salts such as M (NO 3 ) X , MCl X , M (acetate) X , M (CO 3 ) X, and oxides such as MO X. Therefore, the above transition metal materials were mixed with amorphous powder in a weight ratio of 0 to 5%, and then put into an atmosphere furnace, and vacuumed to 10 -10 to 10 -3 atm. At this time, when the degree of vacuumization is low, it is difficult to lower the oxygen partial pressure during the atmosphere treatment. Then, argon was charged until the partial pressure of the reducing atmosphere reached 10 −2 to 1 atm. The reason why such a reducing atmosphere is required is that at least 10 -25 atm of oxygen partial pressure is required in order to obtain non-quantitative titanium dioxide, and for this purpose, it is preferable to use a reducing gas rather than a vacuum method. At this time, hydrogen or carbon monoxide is suitable as the reducing gas used, and a difference in oxygen partial pressure occurs depending on the type of gas used. In addition, even at the same oxygen partial pressure, there is a difference in the surface reactivity of the powder treated with hydrogen and carbon monoxide. As described above, when argon was charged and the partial pressure of the reducing atmosphere reached atmospheric pressure, the reducing gas was filled and then heat-treated at 400 to 750 ° C. for 0.5 to 4 hours while being heated at a rate of 5 ° C. per minute. In this case, when the heat treatment temperature is low or the time is short, the crystallization reaction is not sufficient, and when the temperature is high or the time is long, a rutile phase is obtained instead of the anatase phase. In general, the photocatalytic effect is reported to be excellent in the anatase phase, and the anatase phase is obtained by adjusting the heat treatment temperature and time as described above. Then, by quenching or cooling the heat treatment cooling step, the defect concentration in a high temperature state can be maintained or increased. As described above, during the heat treatment in a reducing atmosphere, the amorphous powder was changed from quantitative titanium dioxide to non-quantitative titanium dioxide deficient in oxygen by a reducing atmosphere, and transition metal material was added to obtain transition metal addition amorphous titanium dioxide. 120)
이러한 비정량 이산화티탄, 특히 전이금속첨가 비정량 이산화티탄은 물질내부에 산소결핍에 의한 결함과 전이금속첨가에 따른 결함을 내포하고 있어서 그 결함레벨이 상승적으로 작용하여 그 효율이 매우 뛰어나다. 특히, 본 발명의 제조공정에서 환원성 분위기 및 전이금속 첨가량을 조절하여 CO 및 NOx등의 자동차 배기가스의 분해에 최적합한 분말을 제조할 수 있다.Such non-quantitative titanium dioxide, in particular, non-quantitative titanium dioxide addition of transition metal contains defects due to oxygen deficiency and defects due to the addition of transition metal in the material, and its defect level acts synergistically, so the efficiency is very excellent. In particular, by adjusting the reducing atmosphere and the amount of transition metal added in the production process of the present invention it can be produced a powder that is optimal for the decomposition of automobile exhaust gases such as CO and NOx.
이상 서술한 바와 같이, 본 발명의 비정량 이산화티탄은 결정구조를 그대로 유지한 체 환원성 분위기내의 산소분압의 변화를 통하여 물질내부에 산소결핍에 의한 결함을 유발하여 광촉매특성을 개선한 효과를 갖는다. 더욱이, 본 발명의 비정량 이산화티탄, 특히 전이금속첨가 비정량 이산화티탄은 물질내부에 산소결핍에 의한 결함과 전이금속첨가에 따른 결함을 내포하고 있어서 그 결함레벨이 상승적으로 작용하여 그 효율이 매우 뛰어나다. 또한, 본 발명은 산소분압 및 전이금속첨가량을 변화시켜 특정용도의 광촉매특성을 갖도록 최적화시킬 수 있는 장점을 지니고 있다. 그에 따라 일산화탄소의 산화반응이나 질소산화물의 환원반응에 최적합한 광촉매물질을 얻을 수 있어 자동차배기가스의 정화처리에 적용하여 뛰어난 효과를 볼 수 있을 것으로 기대된다.As described above, the non-quantitative titanium dioxide of the present invention has the effect of causing defects due to oxygen deficiency in the material through the change of the oxygen partial pressure in the body reducing atmosphere in which the crystal structure is maintained as it is, thereby improving the photocatalytic properties. Furthermore, the amorphous titanium dioxide of the present invention, in particular, the transition metal addition amorphous titanium dioxide contains defects due to oxygen deficiency and defects due to the addition of transition metals in the material, so that the defect level acts synergistically so that the efficiency is very high. outstanding. In addition, the present invention has the advantage that it can be optimized to have a specific photocatalytic properties by changing the oxygen partial pressure and the amount of transition metal addition. As a result, a photocatalytic material that is optimal for the oxidation reaction of carbon monoxide or the reduction of nitrogen oxides can be obtained, and thus, it is expected to have an excellent effect by being applied to the purification process of automobile exhaust gas.
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