KR100506763B1 - Manufacturing method of catalyst for purifying automotive exhaust gas - Google Patents
Manufacturing method of catalyst for purifying automotive exhaust gas Download PDFInfo
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- KR100506763B1 KR100506763B1 KR10-2003-0001839A KR20030001839A KR100506763B1 KR 100506763 B1 KR100506763 B1 KR 100506763B1 KR 20030001839 A KR20030001839 A KR 20030001839A KR 100506763 B1 KR100506763 B1 KR 100506763B1
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0027—Powdering
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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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/024—Multiple impregnation or coating
Abstract
본 발명은 자동차의 배기가스 정화용 촉매의 제조방법에 관한 것으로서, 더욱 상세하게는 종래 촉매에 스트론튬(Sr) 및 프라세오디뮴(Pr)의 혼합원소를 첨가하고 상기 혼합원소의 첨가전에 볼 밀링 공정을 추가 사용함으로써(pre-ball milling), 촉매 표면에 물리적/화학적으로 흡착되어 배기가스의 정화를 방해하는 SO2의 황피독 현상을 현저히 억제할 수 있는 자동차의 배기가스 정화용 촉매의 제조방법에 관한 것이다.The present invention relates to a method for producing a catalyst for purifying exhaust gas of automobiles. More specifically, a mixed element of strontium (Sr) and praseodymium (Pr) is added to a conventional catalyst, and a ball milling process is further used before adding the mixed element. The present invention relates to a method for producing a catalyst for purifying exhaust gases in automobiles, which can significantly suppress the sulfur poisoning phenomenon of SO 2 , which is physically / chemically adsorbed on the surface of the catalyst and prevents the purification of exhaust gases.
Description
본 발명은 자동차의 배기가스 정화용 촉매의 제조방법에 관한 것으로서, 더욱 상세하게는 종래 촉매에 스트론튬(Sr) 및 프라세오디뮴(Pr)의 혼합원소를 첨가하고 상기 혼합원소의 첨가전에 볼 밀링 공정을 추가 사용함으로써(pre-ball milling), 촉매 표면에 물리적/화학적으로 흡착되어 배기가스의 정화를 방해하는 SO2의 황피독 현상을 현저히 억제할 수 있는 자동차의 배기가스 정화용 촉매의 제조방법에 관한 것이다.The present invention relates to a method for producing a catalyst for purifying exhaust gas of automobiles. More specifically, a mixed element of strontium (Sr) and praseodymium (Pr) is added to a conventional catalyst, and a ball milling process is further used before adding the mixed element. The present invention relates to a method for producing a catalyst for purifying exhaust gases in automobiles, which can significantly suppress the sulfur poisoning phenomenon of SO 2 , which is physically / chemically adsorbed on the surface of the catalyst and prevents the purification of exhaust gases.
자동차용 촉매의 피독현상 중 황은 연료에서 기인되는 것으로, 촉매의 표면에 화학적/물리적으로 흡착된 상태로 존재하여 촉매의 정상적인 기능을 방해한다. 상기 촉매는 배기가스와 반응하여 탄화수소(HC), 일산화탄소(CO), 질소산화물(NOx)과 같은 유해한 가스를 질소(N2), 이산화탄소(CO2), H2O 등으로 전환시켜주는 역할을 한다.Sulfur in fuel poisoning of automobile catalysts originates from fuels and is present in a chemically / physically adsorbed state on the surface of the catalyst, thus preventing the normal function of the catalyst. The catalyst reacts with the exhaust gas to convert harmful gases such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) into nitrogen (N 2 ), carbon dioxide (CO 2 ), and H 2 O. do.
일반적으로 배기가스에 존재하는 황은 SO2 형태를 나타내며, 촉매의 스팀 리포밍(steam reforming) 반응(반응식 1)과 워터-기체 이동 반응(wager-gas shift reaction)(반응식 2)을 방해하여 CO, NO의 정화를 방해한다.In general, the sulfur present in the exhaust gas is in the form of SO 2 and interferes with the steam reforming reaction of the catalyst (Scheme 1) and the water-gas shift reaction (Scheme 2). Interfere with the purification of NO.
따라서, 배기가스 중의 SO2가 촉매표면과 반응하지 않도록 하는 것이 촉매의 성능을 향상시키는 방법 중의 하나이다.Therefore, preventing SO 2 in the exhaust gas from reacting with the catalyst surface is one of the methods for improving the performance of the catalyst.
기존의 배기가스 중의 SO2를 제거하는 방법으로는 SO2를 제거하는 장치를 별도로 자동차에 장착하는 방법이 있고, 또는 촉매가 황에 대한 반응을 줄이는 촉매, 즉 내황성이 강한 촉매를 제조하는 방법이 있다. 두 방법을 비교해 볼 때, 효율이 높고 시스템이 간단하면서도 가격면에서 유리한 방법은 후자의 내황성이 강한 촉매는 제조하는 것이다.The existing method of removing SO 2 from exhaust gas is to install a device for removing SO 2 separately in a vehicle, or to prepare a catalyst that reduces the reaction of sulfur to a sulfur, that is, a catalyst having high sulfur resistance. There is this. Comparing the two methods, the more efficient, simpler and cost-effective method is to produce the latter sulfur-resistant catalyst.
한편, 다음 표 1은 FTP-75(federal test procedure-75) 차량에 대한 황의 연료내 농도에 따른 배기가스 배출정도 결과를 나타낸 것이다.On the other hand, Table 1 shows the results of the exhaust gas emissions according to the concentration of sulfur in the fuel for the FTP-75 (federal test procedure-75) vehicle.
상기 표 1의 결과에서 보면, 황의 농도가 증가함에 따라 특히 THC(total hydrocarbon), CO 가스의 배출량이 증가하는 것을 알 수 있다. 따라서, 점점 엄격해지는 배기가스 규제를 만족시키고 THC, CO 배출가스를 줄이기 위해서는 황에 의한 효과를 최소화하는 것이 중요하다.In the results of Table 1, it can be seen that as the concentration of sulfur increases, in particular, the emissions of THC (total hydrocarbon), CO gas increases. Therefore, it is important to minimize the effects of sulfur in order to meet increasingly stringent emission regulations and to reduce THC and CO emissions.
따라서, 본 발명은 종래 문제점을 해결하기 위하여, 촉매표면에 흡착되는 SO2의 양을 줄일 수 있는 원소를 촉매에 첨가하고, 이를 첨가하기 전에 볼 밀링 공정을 포함시켜 가장 간편하고 효과적으로 내황성을 향상시켜 THC 및 CO 배출가스량을 줄일 수 있는 자동차의 배기가스 정화용 촉매의 제조방법을 제공하는 것을 그 목적으로 한다.Therefore, the present invention, in order to solve the conventional problems, by adding an element that can reduce the amount of SO 2 adsorbed on the catalyst surface to the catalyst, including the ball milling process before adding the most easily and effectively improve sulfur resistance It is an object of the present invention to provide a method for producing a catalyst for purification of exhaust gas of automobiles which can reduce the amount of THC and CO emissions.
본 발명은 자동차의 배기가스 정화용 촉매의 제조방법에 있어서,The present invention provides a method for producing a catalyst for purifying exhaust gas of an automobile.
감마 알루미나(γ-Al2O3) 지지체에 팔라듐을 함침시키고 건식 함침(dry impregnation) 상태에서 볼 밀링한 후,After gamma alumina (γ-Al 2 O 3 ) support is impregnated with palladium and ball milled in a dry impregnation state,
스트론튬(Sr) 및 프라세오디뮴(Pr)의 1:1 혼합원소를 전체 촉매에 대하여 1 ∼ 5 중량% 첨가하고,1: 1 mixed element of strontium (Sr) and praseodymium (Pr) is added in an amount of 1 to 5% by weight based on the total catalyst,
습식 함침(Wet Impregnation) 상태에서 다시 볼 밀링하여 워시코트 슬러리를 제조한 후, 담지체에 코팅하고 건조 및 소성시켜 제조하는 자동차의 배기가스 정화용 촉매의 제조방법을 특징으로 한다.After the ball mill in wet impregnation (Wet Impregnation) to prepare a washcoat slurry, it is characterized in that the method for producing a catalyst for purification of exhaust gas of a vehicle manufactured by coating, drying and firing on a carrier.
이하, 본 발명을 더욱 상세하게 설명한다.Hereinafter, the present invention will be described in more detail.
본 발명의 제조방법은 새로운 원소첨가 및 프리 볼 밀링(pre-ball milling) 공정을 통하여, 촉매에 미치는 SO2를 최소화함으로써 본 발명을 완성하게 되었다.The production method of the present invention has completed the present invention by minimizing SO 2 on the catalyst through a new element addition and pre-ball milling process.
본 발명의 촉매 제조방법은 기존 촉매워시코트 제조에서 사용되지 않은 프리 볼 밀링(PRE-BALL MILLING)을 실시하여, SO2에 대한 저항성을 높일 수 있다. 여기서, 상기 워시코트(washcoat)는 극히 미세한 활성 알루미나 입자로된 슬러리를 만든뒤 기질에 도포하여 제조하는 공정을 말한다.In the catalyst production method of the present invention, pre-ball milling (PRE-BALL MILLING), which is not used in the conventional catalyst washcoat, may be performed to increase resistance to SO 2 . Here, the washcoat refers to a process of preparing a slurry made of extremely fine active alumina particles and then applying it to a substrate.
특히, 본 발명은 워시코트 제조공정상에서 밀링(milling)을 상기 혼합원소(Sr+Pr) 첨가 전후에 실시함으로써, 혼합원소(Sr+Pr)의 분산도를 향상시켜 SO2가 촉매표면에서 반응하는 것을 최대한 억제할 수 있다.In particular, the present invention is carried out before and after the addition of the mixed element (Sr + Pr) in the washcoat manufacturing process, to improve the dispersion of the mixed element (Sr + Pr) so that SO 2 reacts on the catalyst surface Can be suppressed as much as possible.
또한, 본 발명은 SO2의 흡착량을 줄일 수 있는 새로운 원소로서 스트론튬(Sr)과 프라세오디뮴(Pr)의 혼합원소를 사용한다.In addition, the present invention uses a mixed element of strontium (Sr) and praseodymium (Pr) as a new element that can reduce the adsorption amount of SO 2 .
그러면 본 발명의 촉매워시코트 제조방법을 보다 구체적으로 설명하면 다음과 같다.Then, the catalyst washcoat manufacturing method of the present invention will be described in more detail.
먼저, 본 발명은 지지체로 사용되는 감마알루미나(γ-Al2O3)에 팔라듐 수용액(PdCl2)을 함침시키고 건식 함침(dry impregnation) 상태에서 상기 혼합원소를 첨가하기 전에 볼 밀링(ball milling)을 실시한다. 이로써, 다음에 첨가되는 혼합원소(Sr+Pr)의 분산도를 향상시킬 수 있다.First, the present invention impregnates gamma alumina (γ-Al 2 O 3 ) used as a support with an aqueous solution of palladium (PdCl 2 ) and adds the mixed element in a dry impregnation state before ball milling. Is carried out. Thereby, the dispersion degree of the mixed element (Sr + Pr) added next can be improved.
이때, 밀링은 분말의 입도가 10 ∼ 100 ㎛ 정도가 되도록 실시하는 것이 바람직하다. 또한, 상기 감마 알루미나의 함량은 80 ∼ 90 중량%로 사용하는 것이 바람직하다. 또한, 상기 팔라듐은 전체 촉매에 대하여 10 g/L 이하로 사용하는 것이 바람직하다.At this time, it is preferable to perform milling so that the particle size of powder may be about 10-100 micrometers. In addition, the content of the gamma alumina is preferably used in 80 to 90% by weight. In addition, the palladium is preferably used in less than 10 g / L with respect to the entire catalyst.
상기 과정 다음으로, 본 발명은 상기 스트론튬과 프라세오디뮴의 혼합원소를 첨가한다.Next to the above process, the present invention adds a mixed element of the strontium and praseodymium.
상기 스트론튬(Sr)과 프라세오디뮴(Pr)의 혼합비율은 1 : 1인 것이 바람직하다. 상기 스트론튬(Sr)과 프라세오디뮴(Pr)의 혼합원소의 사용량은 전체 촉매에 대하여 1 ∼ 5 중량%로 사용하는 것이 바람직하며, 이때 그 함량이 1 중량% 미만이면 SO2 제거효과가 낮아지는 문제가 있고, 5 중량%를 초과하면 SO2 제거효과는 증가하나, 배기가스에 대한 활성이 낮아지는 문제가 있다.The mixing ratio of the strontium (Sr) and praseodymium (Pr) is preferably 1: 1. The amount of the mixed element of strontium (Sr) and praseodymium (Pr) is preferably used in an amount of 1 to 5% by weight based on the total catalyst, and when the content is less than 1% by weight, there is a problem that the SO 2 removal effect is lowered. And, if more than 5% by weight increases the SO 2 removal effect, there is a problem that the activity for the exhaust gas is lowered.
그런 다음, 통상적인 방법으로 습식 함침(Wet Impregnation) 공정을 거친 후 볼밀을 사용하여 밀링 공정을 다시 실시하여 워시코트를 얻는다. 이후, 상기 워시코트 슬러리를 촉매 담지체에 코팅한다. 마지막으로, 건조하고 소성시켜 촉매를 제조한다. 이때, 건조는 250 ℃에서 소성시켜 촉매를 제조한다. 이때, 건조는 250 ℃에서 실시하는 것이 바람직하고, 소성은 350 ℃ 이상에서 실시하는 것이 바람직하다.Then, after the wet impregnation process in a conventional manner, the milling process is performed again using a ball mill to obtain a washcoat. Thereafter, the washcoat slurry is coated on the catalyst carrier. Finally, it is dried and calcined to produce a catalyst. At this time, the drying is calcined at 250 ℃ to prepare a catalyst. At this time, it is preferable to perform drying at 250 degreeC, and it is preferable to perform baking at 350 degreeC or more.
이하, 본 발명을 다음의 실시예 및 비교예를 통하여 상세히 설명하겠는바, 본 발명이 이들에 의해 한정되는 것은 아니다.Hereinafter, the present invention will be described in detail with reference to the following examples and comparative examples, but the present invention is not limited thereto.
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비교예 2Comparative Example 2
기존에 사용되는 워터코트 방식으로 촉매를 제조하였다.The catalyst was prepared by the conventional water coat method.
즉, 감마 알루미나(γ-Al2O3)에 PdCl2 수용액을 함침시키고 건식 함침(dry impregnation) 상태에서 Sr 0.5 ∼ 2.5 중량%를 첨가하였다. 이후, 습식 함침(Wet Impregnation) 상태에서 볼 밀을 사용하여 밀링하여 워시코트 슬러리를 얻었다. 그런 다음, 워시코트 슬러리를 담지체에 코팅하고 건조 및 350 ℃에서 소성시켜 촉매를 제조하였다.That is, gamma alumina (γ-Al 2 O 3 ) was impregnated with PdCl 2 aqueous solution and 0.5 to 2.5% by weight of Sr was added in a dry impregnation state. Thereafter, the wet coat was milled using a ball mill in a wet impregnation state to obtain a washcoat slurry. Then, the washcoat slurry was coated on the support, dried and calcined at 350 ° C. to prepare a catalyst.
비교예 3Comparative Example 3
비교에 2와 동일한 방법으로 실시하되, Sr 대신 Pr을 동일함량으로 사용하여 촉매를 제조하였다.The catalyst was prepared by the same method as in Comparative Example 2, but using Pr in the same amount instead of Sr.
비교예 4Comparative Example 4
비교에 2와 동일한 방법으로 실시하되, Sr 및 Pr의 혼합원소를 사용하여 촉매를 제조하였다.The comparison was carried out in the same manner as 2, but a catalyst was prepared using a mixed element of Sr and Pr.
실시예 1Example 1
감마 알루미나(γ-Al2O3)에 PdCl2 수용액을 함침시키고 건식 함침(dry impregnation) 상태에서 볼 밀링을 실시하였다. 이후, 혼합원소(Sr+Pr=1:1) 1 ∼ 5 중량%를 첨가하였다. 그런 다음, 습식 함침(Wet Impregnation) 상태에서 볼 밀을 사용하여 밀링하여 워시코트 슬러리를 얻었다. 그런 다음, 워시코트 슬러리를 담지체에 코팅하고 250 ℃에서 건조한 후 350 ℃ 이상에서 소성시켜 촉매를 제조하였다.Gamma alumina (γ-Al 2 O 3 ) was impregnated with PdCl 2 aqueous solution and ball milling was performed in a dry impregnation state. Thereafter, 1 to 5% by weight of a mixed element (Sr + Pr = 1: 1) was added. The washcoat slurry was then obtained by milling using a ball mill in wet impregnation. Then, the washcoat slurry was coated on the carrier, dried at 250 ° C and calcined at 350 ° C or higher to prepare a catalyst.
실험예Experimental Example
상기 비교예 1 내지 4 및 실시예 1에 대하여 SO2공급시, 혼합원소(Sr+Pr) 첨가에 따른 NO활성의 변화를 측정하였고, 시험조건은 하기와 같다.In Comparative Examples 1 to 4 and Example 1, the change of NO activity according to the addition of a mixed element (Sr + Pr) was measured when SO 2 was supplied, and test conditions were as follows.
1) 공시(供試) 촉매의 크기: 24 mmφ × 66 mml1) Size of the disclosed catalyst: 24 mmφ × 66 mml
2) 공시 가스 유량: 20 L/MIN(SV = 40000/H)2) Disclosure gas flow rate: 20 L / MIN (SV = 40000 / H)
3) 공시 가스 조성(평균치)3) Public gas composition (average value)
승온속도는 10 ℃/min이고 450 ℃까지 가스 실험하였다. NO정화율 결과는 도 1 및 2에 나타내었다.The temperature increase rate was 10 ℃ / min and gas experiment to 450 ℃. NO purification results are shown in FIGS. 1 and 2.
도 1은 비교예 2 내지 3 및 실시예 1의 정화율 결과를 비교하여 나타낸 것이다. 본 발명의 실시예 1(Sr+Pr)은 비교예 2(Sr 첨가) 및 비교예 3(Pr첨가)보다 더욱 효과적임을 알 수 있다.Figure 1 shows a comparison of the purification rate results of Comparative Examples 2 and 3 and Example 1. It can be seen that Example 1 (Sr + Pr) of the present invention is more effective than Comparative Example 2 (Sr addition) and Comparative Example 3 (Pr addition).
또한, 도 2의 평가 결과는 Sr+Pr를 첨가한 촉매에서 프리-볼 밀링(Pre-ball milling) 처리에 따른 효과를 나타낸 것이다. 도 2의 결과에서 알 수 있듯이, 본 발명의 실시예 1과 같이 프리 볼밀링을 처리를 함으로써 약 10% 정도의 NO정화율이 향상되었다. 이것은 프리 볼밀링처리를 함으로써, Sr+Pr의 분산도를 향상시켜, SO2가 촉매 표면에 흡착되는 것을 억제시킨 효과라 하겠다.In addition, the evaluation results of Figure 2 shows the effect of the pre-ball milling (Pre-ball milling) treatment in the catalyst added with Sr + Pr. As can be seen from the result of FIG. 2, the NO purification rate of about 10% was improved by pre-ball milling as in Example 1 of the present invention. This preliminary ball milling treatment improves the degree of dispersion of Sr + Pr and suppresses the adsorption of SO 2 to the catalyst surface.
이상에서 설명한 바와 같이, 본 발명의 제조방법은 종래 촉매에 스트론튬(Sr) 및 프라세오디뮴(Pr)의 혼합원소를 첨가하고 상기 혼합원소의 첨가전에 볼 밀링 공정을 추가 사용함으로써(pre-ball milling), 내황성이 강한 촉매를 제조하여 자동차 배기가스의 정화율을 향상시킬 수 있다.As described above, the production method of the present invention by adding a mixed element of strontium (Sr) and praseodymium (Pr) to the conventional catalyst and using a ball milling process before the addition of the mixed element (pre-ball milling), The sulfur-resistant catalyst can be prepared to improve the purification rate of automobile exhaust gas.
도 1은 본 발명의 실시예 1의 촉매 및 종래 비교예 1 내지 3의 촉매에 대하여 온도에 따른 NO 정화율 결과를 비교하여 나타낸 것이다.FIG. 1 compares the results of NO purification rate according to temperature with respect to the catalyst of Example 1 of the present invention and the catalysts of Comparative Examples 1 to 3.
도 2는 본 발명의 실시예 1의 촉매 및 종래 비교예 4의 촉매에 대하여 온도에 따른 NO 정화율 결과를 비교하여 나타낸 것이다.FIG. 2 shows the results of comparing the NO purification rate according to temperature with respect to the catalyst of Example 1 and the catalyst of Comparative Example 4 of the present invention.
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