WO2018227891A1 - 一种用于净化挥发性有机物的催化剂及其制备方法 - Google Patents

一种用于净化挥发性有机物的催化剂及其制备方法 Download PDF

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WO2018227891A1
WO2018227891A1 PCT/CN2017/113111 CN2017113111W WO2018227891A1 WO 2018227891 A1 WO2018227891 A1 WO 2018227891A1 CN 2017113111 W CN2017113111 W CN 2017113111W WO 2018227891 A1 WO2018227891 A1 WO 2018227891A1
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catalyst
volatile organic
organic compounds
palladium
honeycomb ceramic
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PCT/CN2017/113111
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French (fr)
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付名利
甘琪
贺辉
吴军良
叶代启
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华南理工大学
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Priority to US16/620,884 priority Critical patent/US11642659B2/en
Publication of WO2018227891A1 publication Critical patent/WO2018227891A1/zh

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    • B01D2257/708—Volatile organic compounds V.O.C.'s
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    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the invention relates to the field of air pollution control technology and environmental protection catalytic material, in particular to a catalyst for purifying volatile organic compounds and a preparation method thereof.
  • VOCs volatile organic compounds
  • the emission of volatile organic compounds (VOCs) directly affects human health and environmental quality. And after the secondary conversion of VOCs, ozone O 3 and fine particles PM 2.5 are formed, which is the main cause of smog formation.
  • the commonly used VOCs control technologies mainly include recovery method and destruction method.
  • the destruction method mainly includes combustion method, biological method, plasma method and photocatalysis method. Combustion is recognized as one of the most effective and thorough purification methods for VOCs. Catalytic combustion is widely used because of the introduction of catalysts, which lowers the reaction temperature and saves energy.
  • the core of the technology is catalyst.
  • catalytic oxidation generally employs a monolithic catalyst, such as coating a ⁇ -Al 2 O 3 (alumina)-based support on a cordierite honeycomb ceramic substrate, and finally supporting an active component such as a platinum group noble metal.
  • the catalyst and its preparation method have two key points, the first being a ⁇ -Al 2 O 3 -based carrier and the second being an active component such as a platinum group noble metal.
  • the ⁇ -Al 2 O 3 -based carrier mainly functions as a highly dispersed active component, ensures high activity and high temperature resistance of the catalyst, and has properties such as binding of the active component to the matrix; active groups such as platinum group noble metals The fraction provides direct high activity of the catalyst.
  • the ⁇ -Al 2 O 3 -based carrier is prone to high-temperature sintering, cracking, and shedding, so it is necessary to strengthen and optimize the performance of the carrier.
  • Most of the modified elements are taken from rare earths such as lanthanide metals, transition metals, etc., such as cerium oxide, antimony trioxide, etc., and zirconia; in order to ensure the activity and stability of these catalysts, active components such as platinum group noble metals must not be used. Less, but often the load is higher, generally more than 0.05%, even as high as 1 ⁇ 5%.
  • some catalysts have a noble metal content of less than 10,000 parts per million (the palladium content of the catalyst is 0.1-0.4 g/L, and the catalyst is converted), but the active component also contains nickel, and is used in the preparation process.
  • the nitric acid and vacuum conditions, etc., the preparation process is relatively complicated. Therefore, the existing such catalysts have the disadvantages that the modification is too complicated, the preparation process is relatively long, the precious metal load is high, and the cost is also high.
  • a catalyst for purifying volatile organic compounds comprises a cordierite honeycomb ceramic matrix, an iron, cobalt, nickel modified gamma-Al 2 O 3 support, and an active component of a very low content of a mixture of platinum and palladium.
  • the present invention also provides a process for the preparation of a catalyst for purifying volatile organic compounds.
  • the present invention is achieved by the following technical solutions.
  • the cobalt-nickel modified alumina is used as a carrier, the cordierite honeycomb ceramic is used as a matrix, and a very low content of a mixture of platinum and palladium is used as an active component; the modified alumina carrier is coated on a cordierite honeycomb ceramic substrate.
  • the active component is supported on the modified alumina support;
  • the molar ratio of platinum to palladium is 0 ⁇ 1: 0 ⁇ 9, and the mixture of platinum and palladium accounts for 0.01% ⁇ 0.05% of the mass of the matrix.
  • the amount of the carrier accounts for 3% to 5% of the mass of the substrate.
  • a method for preparing a catalyst for purifying volatile organic compounds comprising the steps of:
  • cordierite honeycomb ceramic substrate coated with modified alumina is placed in a pulse dielectric barrier discharge reaction zone, and the discharge strengthening pretreatment is performed to obtain a modified alumina-coated cordierite honeycomb ceramic pretreated by discharge strengthening.
  • the discharge-fortified pretreated coated alumina-coated cordierite honeycomb ceramic substrate obtained by the step (2) is immersed in the step (3) In the obtained active component impregnation liquid, the immersion liquid remaining in the pores of the honeycomb ceramic substrate is taken out, dried in an air atmosphere, calcined, and finally reduced to obtain the catalyst for purifying volatile organic compounds.
  • the concentration of the mixed solution of the iron salt, the cobalt salt and the nickel salt is 2.62 to 4.64 g/mL. .
  • the concentration of the water-soluble colloid of the aluminum hydroxide is 3.25 to 4.93 g/mL.
  • the iron salt, the cobalt salt, and the nickel salt are nitrates or acetates of iron, cobalt, and nickel.
  • the molar ratio of iron, cobalt, nickel and aluminum in the mixture of the solution and the colloid is 1 ⁇ 2: 1 ⁇ 2: 1 ⁇ 2: 4 ⁇ 7.
  • the immersion time is 20 to 30 minutes.
  • the drying is performed at 120 ° C for 3 to 6 hours.
  • the baking is performed at 500 to 700 ° C for 1 to 3 hours.
  • the discharge strengthening pretreatment is: the discharge condition is atmospheric pressure, and the medium thickness is 1 mm to 5 mm.
  • the voltage is 5000 ⁇ 20000V, the frequency is 50 ⁇ 400Hz, and the pulse width is 100 ⁇ 200ns.
  • the time of the discharge strengthening pretreatment is 5 to 10 minutes.
  • the precursor of the platinum is chloroplatinic acid.
  • the precursor of the palladium is palladium chloride.
  • the total content of platinum and palladium in the active component impregnation liquid is 1.65 to 8.26 g/L. .
  • the immersion time is 20 to 30 minutes.
  • the drying is performed at 120 ° C for 3 to 6 hours.
  • the baking is performed at 500 to 700 ° C for 1 to 3 hours.
  • the reduction is carried out in an H 2 /N 2 atmosphere.
  • the volume ratio of H 2 to N 2 in the H 2 /N 2 atmosphere is 5:95.
  • the reduction is carried out at a temperature of 200 to 250 ° C for 2 to 4 hours.
  • the present invention has the following advantages and benefits:
  • the invention adopts ⁇ -Al 2 O 3 modified by iron, cobalt and nickel as a carrier, and uses a mixture of platinum and palladium with a very low content as an active component, thereby overcoming the existing catalyst for purifying volatile organic compounds.
  • the modification is too complicated, the preparation process is tedious, the precious metal load is high, and the cost is also high;
  • the cordierite honeycomb ceramic substrate coated with the modified alumina is placed in the pulse dielectric barrier discharge reaction zone for strengthening pretreatment, and the process is simple, and the catalyst activity is further improved;
  • the catalyst has high dispersion of the active component of the precious metal in the performance, and the active component is tightly combined with the matrix to ensure excellent performance of the catalyst with high activity and high temperature resistance;
  • the catalyst of the invention has good low temperature activity and excellent high temperature resistance, completely oxidizes toluene at 230 ° C; after continuous operation for 200 h at a high temperature of 500 to 700 ° C, complete oxidation of toluene can be achieved at 255 ° C.
  • Figure 1 is a schematic diagram of a device for enhanced pretreatment of pulsed dielectric barrier discharge.
  • FIG. 1 A schematic diagram of a device for pulse dielectric barrier discharge enhanced pretreatment used in the embodiment of the present invention is shown in FIG. 1 and includes a high voltage electrode 1 and a medium 3 And a grounding electrode 4, a cordierite honeycomb ceramic coated with an iron, cobalt, nickel modified alumina carrier as a substrate 2 is placed in a reaction zone between the high voltage electrode 1 and the medium 3; wherein the discharge condition is atmospheric pressure, the medium thickness 1mm ⁇ 5mm, voltage 5000 ⁇ 20000V, frequency 50 ⁇ 400Hz, pulse width 100 ⁇ 200ns Under the above conditions, the cordierite honeycomb ceramic coated with iron, cobalt and nickel modified alumina carrier was used as the matrix 2 in the pulse dielectric barrier discharge reaction zone for 5 ⁇ 10 min.
  • the mixed solution of the iron salt, the cobalt salt and the nickel salt is mixed with the water-soluble colloid of aluminum hydroxide, and the iron salt, the cobalt salt and the nickel salt are Fe(NO 3 ) 3 ⁇ 9H 2 O , Co(AC) 3 ⁇ 4H 2 O , Ni(NO 3 ) 4 ⁇ 6H 2 O , specifically weigh 22.5231g Fe(NO 3 ) 3 ⁇ 9H 2 O , 13.8872g Co(AC) 3 ⁇ 4H 2 O , 16.0482g Ni (NO 3 ) 4 ⁇ 6H 2 O is dissolved in 20ml of deionized water, and mixed with colloid containing 20ml of deionized water and 65.0166g of aluminum hydroxide, magnetically stirred; prepared mixture, iron, cobalt, nickel, aluminum The molar ratio is 1: 1 : 1 : 7 ;
  • the cordierite honeycomb ceramic is immersed in the mixture of the above salt solution and the colloid for 20 minutes, and the modified alumina is coated, and the coating amount accounts for the mass of the substrate. 3%, finally, under air atmosphere, dried at 120 °C for 3 h and calcined at 500 °C for 3 h to obtain a cordierite honeycomb ceramic substrate coated with modified alumina.
  • Steps 1 The cordierite honeycomb ceramic substrate coated with modified alumina is placed in a pulse dielectric barrier discharge reaction zone, and the discharge condition is a dielectric thickness of 1 mm at atmospheric pressure, a voltage of 5000 V, a frequency of 50 Hz, and a pulse width. After 100 ns, the pretreatment was strengthened for 5 min to obtain a modified alumina-coated cordierite honeycomb ceramic substrate pretreated by discharge strengthening.
  • the active component impregnation solution of platinum and palladium mixture is prepared, and chloroplatinic acid and palladium chloride are respectively dissolved in deionized water, and then mixed, and platinum and palladium are prepared in a molar ratio of 1:9; specifically, 0.015 g is weighed.
  • the modified alumina-coated cordierite honeycomb ceramic substrate pretreated by the pulse dielectric barrier discharge strengthening obtained in the step (2) is immersed in the active component impregnation liquid obtained in the step (3) for 20 minutes;
  • Pd-Pt/Fe-Co-Ni-O- ⁇ -Al 2 O 3 / cordierite honeycomb ceramics measuring 100 mm ⁇ 100 mm ⁇ 50 mm are cut into four cylinders of 30 mm ⁇ 50 mm in length, one of which is taken. Loaded into the catalytic reactor.
  • Catalyst performance evaluation was carried out in a fixed-bed flow reactor. Toluene was used as a representative of volatile organic compounds. Toluene was immersed in an ice-water mixture bath. The toluene-air mixture was taken out by air bubbling to form a simulated exhaust gas with a toluene content of 3490 ⁇ . 50 mg ⁇ m -3 , the reaction space velocity was controlled to 15000 h -1 , and the concentration of toluene fed into the evaluation device was analyzed by FID of gas chromatograph GC2014C.
  • the catalyst prepared in this example was subjected to catalytic oxidation reaction at 250 °C for 200 h after continuous operation at 500 °C.
  • the mixed solution of the iron salt, the cobalt salt and the nickel salt is mixed with the water-soluble colloid of aluminum hydroxide, and the iron salt, the cobalt salt and the nickel salt are Fe(NO 3 ) 3 ⁇ 9H 2 O , Co(AC) 3 ⁇ 4H 2 O , Ni(NO 3 ) 4 ⁇ 6H 2 O , specifically weigh 39.9530g Fe(NO 3 ) 3 ⁇ 9H 2 O , 24.6339g Co(AC) 3 ⁇ 4H 2 O , 28.4672g Ni (NO 3 ) 4 ⁇ 6H 2 O is dissolved in 25ml of deionized water and mixed with colloid containing 15ml of deionized water and 60.4111g of aluminum hydroxide, magnetically stirred; the mixture of iron, cobalt, nickel and aluminum is prepared.
  • the ratio is 1.5 : 1.5 : 1.5 : 5.5 ;
  • the cordierite honeycomb ceramic is immersed in the mixture of the above salt solution and the colloid for 25 minutes, and the modified alumina is coated, and the coating amount accounts for the mass of the substrate. 4%, finally baked in an air atmosphere at 120 ° C for 4 h and 600 ° C for 2 h to obtain a cordierite honeycomb ceramic substrate coated with modified alumina.
  • Steps 1 The cordierite honeycomb ceramic substrate coated with modified alumina is placed in a pulse dielectric barrier discharge reaction zone, and the discharge condition is a dielectric thickness of 3 mm under atmospheric pressure, a voltage of 10000 V, a frequency of 200 Hz.
  • the pulse width was 150 ns and the pretreatment was strengthened for 8 min to obtain a cordierite honeycomb ceramic substrate coated with modified alumina pretreated by discharge strengthening.
  • the palladium active component impregnation liquid was prepared, and palladium chloride was dissolved in deionized water. Specifically, 0.3303 g of PdCl 2 was weighed and dissolved in 40 ml of water to obtain an active component impregnation liquid having a palladium content of 4.95 g/L.
  • the modified alumina-coated cordierite honeycomb ceramic substrate pretreated by the pulse dielectric barrier discharge strengthening obtained in the step (2) is immersed in the active component impregnation liquid obtained in the step (3) for 25 minutes;
  • Pd/Fe-Co-Ni-O- ⁇ -Al 2 O 3 / cordierite honeycomb ceramics measuring 100mm ⁇ 100mm ⁇ 50mm are cut into four cylinders with a diameter of 30mm ⁇ 50mm and can be loaded into one. In the catalytic reactor.
  • Catalyst performance evaluation was carried out in a fixed-bed flow reactor. Toluene was used as a representative of volatile organic compounds. Toluene was immersed in an ice-water mixture bath. The toluene-air mixture was taken out by air bubbling to form a simulated exhaust gas with a toluene content of 3490 ⁇ . 50 mg ⁇ m -3, a space velocity of the reaction is controlled to 15000h -1, evaluation means export toluene GC2014C concentration by gas chromatography analysis of FID.
  • the catalyst prepared in this example was subjected to catalytic oxidation reaction of toluene at 255 °C for 200 h after continuous operation at 600 °C.
  • the cordierite honeycomb ceramic is immersed in the mixture of the above salt solution and the colloid for 30 minutes, and the modified alumina is coated, and the coating amount accounts for the mass of the substrate. 5%, finally baked in an air atmosphere at 120 ° C for 6 h and 700 ° C for 1 h to obtain a cordierite honeycomb ceramic substrate coated with modified alumina.
  • Steps 1 The cordierite honeycomb ceramic substrate coated with modified alumina is placed in a pulse dielectric barrier discharge reaction zone, and the discharge condition is a dielectric thickness of 5 mm under atmospheric pressure, a voltage of 20000 V, a frequency of 400 Hz.
  • the pulse width was 200 ns and the pretreatment was strengthened for 10 min to obtain a cordierite honeycomb ceramic substrate coated with modified alumina pretreated by discharge strengthening.
  • the palladium active component impregnation solution is prepared, and the chloroplatinic acid is dissolved in deionized water, specifically 0.8770 g of H 2 PtCl 6 ⁇ 6H 2 O is weighed and dissolved in 40 ml of water to obtain an active group having a platinum content of 8.26 g/L. Distillate.
  • the modified alumina-coated cordierite honeycomb ceramic substrate pretreated by the pulse dielectric barrier discharge strengthening obtained in the step (2) is immersed in the active component impregnation liquid obtained in the step (3) for 30 minutes;
  • Pt/Fe-Co-Ni-O- ⁇ -Al 2 O 3 / cordierite honeycomb ceramics measuring 100mm ⁇ 100mm ⁇ 50mm are cut into four cylinders with a diameter of 30mm ⁇ 50mm, which can be loaded into one. In the catalytic reactor.
  • Catalyst performance evaluation was carried out in a fixed bed flow reactor with toluene as a volatile organic representative.
  • Toluene ice-water mixture from the heat bath, bubbled with air using toluene - simulated exhaust gas air mixture is formed, wherein the toluene content is 3490 ⁇ 50 mg ⁇ m -3, a space velocity of the reaction is controlled to 15000h -1, toluene evaluation apparatus Importers
  • the concentration was analyzed by the FID of the gas chromatograph GC2014C.
  • the catalyst prepared in this example was subjected to catalytic oxidation reaction at 255 °C for 200 h after continuous operation at 700 °C.
  • the overall catalyst of the present invention has high catalytic activity at a lower temperature in the purification of volatile organic compounds represented by toluene;
  • the catalyst preparation process of the invention has the advantages of simple preparation process, extremely low precious metal content, high thermal stability, low production cost, easy promotion, and broad application prospect.

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Abstract

一种用于净化挥发性有机物的催化剂及其制备方法。该催化剂以铁、钴、镍改性的氧化铝为载体，以堇青石蜂窝陶瓷为基体，以极低含量的铂和钯的混合物为活性组分；铂与钯的摩尔比为0~1：0~9，且铂和钯的混合物的量占基体质量的0.01%~0.05%；载体的量占基体质量的3%~5%。催化剂制备方法包括步骤：（1）载体的涂覆；（2）放电强化预处理；（3）活性组分浸渍液的制备；（4）活性组分的负载与还原。该方法克服了现有用于净化挥发性有机物的催化剂存在改性过于复杂，制备工艺过程冗长，贵金属负载量高，从而导致成本也较高等不足，制备具有良好的低温活性和优异的耐高温性能的催化剂。

Description

一种用于净化挥发性有机物的催化剂及其制备方法
技术领域
本发明涉及大气污染治理技术和环保催化材料领域，具体涉及一种用于净化挥发性有机物的催化剂及其制备方法。
背景技术
挥发性有机物（ VOCs ）的排放直接影响人体健康和环境质量。且 VOCs 经过二次转化，会生成臭氧 O3 和细颗粒物 PM2.5 ，后者即为雾霾形成的主因。鉴于 VOCs 直接和间接均会对人体健康、生态环境造成极大的危害，目前国家已高度重视 VOCs 的控制。常用的 VOCs 控制技术主要有回收法和销毁法，其中，销毁法主要包括燃烧法、生物法、等离子法和光催化法等。燃烧法是公认的最有效和最彻底的 VOCs 净化方法之一；而催化燃烧法由于催化剂的引入，降低了反应温度，节约了能源，从而得到广泛应用，其技术核心是催化剂。
当前，催化氧化一般采用整体式催化剂，如在堇青石蜂窝陶瓷基体上涂覆 γ-Al2O3 （氧化铝）基载体，最后负载铂族贵金属等活性组分。这种催化剂及其制备方法有两个关键之处，第一是 γ-Al2O3 基载体，第二是铂族贵金属等活性组分。其中 γ-Al2O3 基载体主要起到高度分散活性组分的作用，保证催化剂的高活性和耐高温性，并且具有能让活性组分与基体紧密结合等性能；铂族贵金属等活性组分则直接提供催化剂的高活性。
目前，在实际废气净化中， γ-Al2O3 基载体容易发生高温烧结、龟裂和脱落等现象，因此有必要对载体进行性能强化和优化。改性的元素大多取自稀土如镧系金属、过渡金属等，如二氧化铈、三氧化二镧等以及氧化锆；为保证这些催化剂活性及其稳定性，铂族贵金属等活性组分必不可少，但往往负载量较高，一般超过 0.05% ，甚至高达 1~5% 。当然，也有的催化剂其活性组分贵金属含量低于万分之七（催化剂中钯含量为 0.1~0.4g/L ， 催化剂折合而来），不过其活性组分还含有镍，且制备过程中用了硝酸和真空条件等，制备工艺相对复杂。因此，现有的此类催化剂存在改性过于复杂，制备工艺过程也较为冗长，贵金属负载量高，从而导致成本也较高等缺点。
发明内容
为了克服现有用于净化挥发性有机物的催化剂存在改性过于复杂，制备工艺过程冗长，贵金属负载量高，从而导致成本高等不足，本发明提供了一种制备过程简单，贵金属负载量极低的用于净化挥发性有机物的催化剂。该催化剂包括堇青石蜂窝陶瓷基体，铁、钴、镍改性的 γ-Al2O3 载体，极低含量铂和钯混合物的活性组分。
本发明还提供了所述的一种用于净化挥发性有机物的催化剂的制备方法。
本发明通过如下技术方案实现。
一种用于净化挥发性有机物的催化剂，以铁、 钴、镍改性的氧化铝为载体，以堇青石蜂窝陶瓷为基体，以极低含量的铂和钯的混合物为活性组分；改性的氧化铝载体涂覆在堇青石蜂窝陶瓷基体上，活性组分负载在改性的氧化铝载体上；
所述铂与钯的摩尔比为 0~1 ： 0~9 ，且铂和钯的混合物的量 占基体质量的 0.01%~0.05% ；所述载体的量占基体质量的 3%~5% 。
制备所述的一种用于净化挥发性有机物的催化剂的方法，包括如下步骤：
（ 1 ）载体的涂覆：
将铁盐、钴盐、镍盐的混合溶液与氢氧化铝的水溶性胶体混合，得到溶液与胶体的混合液；将堇青石蜂窝陶瓷浸渍于得到的溶液与胶体的混合液中，取出，空气气氛下干燥、焙烧，得到涂覆了改性氧化铝的堇青石蜂窝陶瓷基体；
（ 2 ）放电强化预处理：
将得到的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内，放电强化预处理，得到经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体；
（ 3 ）活性组分浸渍液的制备：
将铂的前驱物与钯的前驱物用去离子水溶解，混合，得到活性组分浸渍液；
（ 4 ）活性组分的负载与还原：
将步骤（ 2 ）得到的经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体浸渍于步骤（ 3 ）得到的活性组分浸渍液中，取出，除去残留于蜂窝陶瓷基体孔道中的浸渍液，空气气氛下干燥、焙烧，最后进行还原，得到所述用于净化挥发性有机物的催化剂。
进一步地，步骤（ 1 ）中，所述铁盐、钴盐、镍盐的混合溶液的浓度为 2.62~4.64 g/mL 。
进一步地，步骤（ 1 ）中，所述氢氧化铝的水溶性胶体的浓度为 3.25~4.93 g/mL 。
进一步地，步骤（ 1 ）中，所述铁盐、钴盐、镍盐为铁、钴、镍的硝酸盐或醋酸盐。
进一步地，步骤（ 1 ）中，所述溶液与胶体的混合液中，铁、钴、镍和铝的摩尔比为 1~2 ： 1~2 ： 1~2 ： 4~7 。
进一步地，步骤（ 1 ）中，所述浸渍的时间为 20~30min 。
进一步地，步骤（ 1 ）中，所述干燥是在 120 ℃干燥 3~6h 。
进一步地，步骤（ 1 ）中，所述焙烧是在 500~700 ℃焙烧 1~3h 。
进一步地，步骤（ 2 ）中，所述放电强化预处理为：放电条件为大气压下，介质厚度为 1mm~5mm ，电压为 5000~20000V ，频率为 50~400Hz ，脉宽为 100~200ns 。
进一步地，步骤（ 2 ）中，所述 放电强化预处理的时间为 5~10min 。
进一步地， 步骤（ 3 ）中，所述铂的前驱物为氯铂酸。
进一步地， 步骤（ 3 ）中，所述钯的前驱物为氯化钯。
进一步地，步骤（ 3 ）中，所述活性组分浸渍液中，铂与钯的总含量为 1.65~8.26 g/L 。
进一步地，步骤（ 4 ）中，所述浸渍的时间为 20~30min 。
进一步地，步骤（ 4 ）中，所述干燥是在 120 ℃干燥 3~6h 。
进一步地，步骤（ 4 ）中，所述焙烧是在 500~700 ℃焙烧 1~3h 。
进一步地，步骤（ 4 ）中，所述还原是在 H2/N2 气氛中进行，优选的， H2/N2 气氛中， H2 与 N2 的体积比为 5 ： 95 。
进一步地，步骤（ 4 ）中，所述还原是在 200~250 ℃温度下还原 2~4h 。
与现有技术相比，本发明具有如下优点和有益效果：
（ 1 ）本发明以铁、钴、镍改性的 γ-Al2O3 为载体，并以极低含量铂和钯的混合物为活性组分，克服了现有用于净化挥发性有机物的催化剂存在改性过于复杂，制备工艺过程冗长，贵金属负载量高，从而导致成本也较高等不足；
（ 2 ）本发明 在催化剂的制备工艺上，对涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内进行强化预处理，工艺简单，进一步提高催化剂活性；
（ 3 ）本发明 的催化剂，在性能上，贵金属活性组分分散度高，活性组分与基体紧密结合，保证了催化剂高活性、耐高温等优异的性能；
（4 ）本发明催化剂具有良好的低温活性和优异的耐高温性能，230℃下完全氧化甲苯；在500~700℃的高温条件下连续运行200h后，255℃下可实现对甲苯的完全氧化。
附图说明
图 1 为脉冲介质阻挡放电强化预处理的装置示意图。
具体实施方式
下面结合具体实施例，进一步具体说明该类催化剂的制备方法，同时具体描述其性能测试结果，但本发明并不限于这些实施例。
本发明实施例中采用的脉冲介质阻挡放电强化预处理的装置示意图如图 1 所示，包括高压电极 1 、介质 3 和接地极 4 ，涂覆了铁、钴、镍改性氧化铝载体的堇青石蜂窝陶瓷为基体 2 放置在高压电极 1 和介质 3 之间的反应区中；其中，放电条件为大气压下，介质厚度 1mm~5mm ，电压 5000~20000V ，频率 50~400Hz ，脉宽 100~200ns ；在上述条件下，涂覆了铁、钴、镍改性氧化铝载体的堇青石蜂窝陶瓷为基体 2 在脉冲介质阻挡放电反应区内强化预处理 5~10min 。
实施例 1
（ 1 ）改性氧化铝在堇青石蜂窝陶瓷基体上的涂覆
将铁盐、钴盐、镍盐的混合溶液与氢氧化铝的水溶性胶体混合，所述的铁盐、钴盐、镍盐为 Fe(NO3)3·9H2O 、 Co(AC)3·4H2O 、 Ni(NO3)4·6H2O ，具体是称取 22.5231g Fe(NO3)3·9H2O 、 13.8872g Co(AC)3·4H2O 、 16.0482g Ni(NO3)4·6H2O 溶于 20ml 去离子水，并与含 20ml 去离子水和 65.0166g 氢氧化铝的胶体混合，磁磁力搅拌；配制得到的混合液中，铁、钴、镍、铝的摩尔比为 1 ： 1 ： 1 ： 7 ；
将堇青石蜂窝陶瓷浸渍于上述盐溶液与胶体的混合液中 20min ，进行改性氧化铝的涂覆，涂覆量占基体质量的 3% ，最后在空气气氛下，于 120 ℃ 干燥 3h 和 500 ℃ 焙烧 3h ， 得到涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 2 ）涂覆了改性氧化铝的堇青石蜂窝陶瓷基体的放电强化预处理
将步骤（ 1 ）中得到的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内，放电条件为大气压下介质厚度 1mm ，电压 5000V ，频率 50Hz ，脉宽 100ns ， 强化预处理 5min ，得到经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 3 ）活性组分浸渍液的制备
配制铂和钯混合物的活性组分浸渍液，分别将氯铂酸和氯化钯用去离子水溶解，再混合，铂与钯是以摩尔比为 1 ： 9 进行调配；具体是称取 0.0915g PdCl2 、 0.0297g H2PtCl6·6H2O ，溶于 40ml 水，得到铂和钯的混合物含量为 1.65g/L 的活性组分浸渍液。
（ 4 ）活性组分的负载与还原
将步骤（ 2 ）得到的经脉冲介质阻挡放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体浸渍于步骤（ 3 ）得到的活性组分浸渍液中 20min ；然后取出，除去残留于蜂窝陶瓷基体孔道中的浸渍液，在空气气氛下，于 120 ℃ 干燥 3h 和 500 ℃ 焙烧 3h ；最后在 H2/N2 气氛（ H2/N2 =5 ： 95 ， V/V ）中，于 200 ℃ 下还原 4h ，得到以极低含量铂和钯的混合物为活性组分的催化剂，其活性组分占基体质量的 0.01% 。
（ 5 ）催化剂的性能评价
将尺寸为 100mm×100mm×50mm 的 Pd-Pt/Fe-Co-Ni-O-γ-Al2O3/ 堇青石蜂窝陶瓷切割成四个直径为 30mm× 长 50mm 的圆柱体，任取其中一个装入催化反应器中。
催化剂性能评价在固定床流动反应器中进行，以甲苯为挥发性有机物代表物，甲苯由冰水混合物浸浴保温，采用空气鼓泡带出甲苯 - 空气混合物形成模拟废气，其中甲苯含量为 3490±50 mg·m-3 ，反应空速控制为 15000h-1 ，评价装置进出口甲苯的浓度用气相色谱仪 GC2014C 的 FID 进行分析。
甲苯的转化率则用下式进行计算：
甲苯的转化率（ Conv ， % ） =[( 进口甲苯浓度 Conci- 出口甲苯浓度 Conco)/ 进口甲苯浓度 Conci]×100% 。
每个温度下，当催化氧化反应达到稳定状态 5min 后，再进行成分的分析。
本实施例制备的催化剂在 230 ℃ 下， Conci=3540 mg·m-3 ， Conco=36 mg·m-3 ，甲苯的转化率 Conv 为 98.98% 。
本实施例制备的催化剂在 500 ℃ 下连续运行 200h 后，在 250 ℃ 下对甲苯进行催化氧化反应试验，试验结果如下： Conci=3535 mg·m-3 ， Conco=39 mg·m-3 ，甲苯的转化率 Conv 为 98.90% 。
实施例 2
（ 1 ）改性氧化铝在堇青石蜂窝陶瓷基体上的涂覆
将铁盐、钴盐、镍盐的混合溶液与氢氧化铝的水溶性胶体混合，所述的铁盐、钴盐、镍盐为 Fe(NO3)3·9H2O 、 Co(AC)3·4H2O 、 Ni(NO3)4·6H2O ，具体是称取 39.9530g Fe(NO3)3·9H2O 、 24.6339g Co(AC)3·4H2O 、 28.4672g Ni(NO3)4·6H2O 溶于 25ml 去离子水，并与含 15ml 去离子水和 60.4111g 氢氧化铝的胶体混合，磁力搅拌；配制得到的混合液中，铁、钴、镍、铝的摩尔比为 1.5 ： 1.5 ： 1.5 ： 5.5 ；
将堇青石蜂窝陶瓷浸渍于上述盐溶液与胶体的混合液中 25min ，进行改性氧化铝的涂覆，涂覆量占基体质量的 4% ，最后在空气气氛下，于 120 ℃ 干燥 4h 和 600 ℃ 焙烧 2h ， 得到涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 2 ）涂覆了改性氧化铝的堇青石蜂窝陶瓷基体的放电强化预处理
将步骤（ 1 ）中得到的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内，放电条件为大气压下介质厚度 3mm ，电压 10000V ，频率 200Hz ，脉宽 150ns ，强化预处理 8min ，得到经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 3 ）活性组分浸渍液的制备
配制钯活性组分浸渍液，将氯化钯用去离子水溶解，具体是称取 0.3303g PdCl2 ，溶于 40ml 水，得到钯含量为 4.95g/L 的活性组分浸渍液。
（ 4 ）活性组分的负载与还原
将步骤（ 2 ）得到的经脉冲介质阻挡放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体浸渍于步骤（ 3 ）得到的活性组分浸渍液中 25min ；然后取出，除去残留于蜂窝陶瓷基体孔道中的浸渍液，在空气气氛下，于 120 ℃ 干燥 4h 和 600 ℃ 焙烧 2h ；最后在 H2/N2 气氛（ H2/N2 =5 ： 95 ， V/V ）中，于 225 ℃ 下还原 3h ，得到以极低含量钯为活性组分的催化剂，其活性组分占基体质量的 0.03% 。
（ 5 ）催化剂的性能评价
将尺寸为 100mm×100mm×50mm 的 Pd/Fe-Co-Ni-O-γ-Al2O3/ 堇青石蜂窝陶瓷切割成四个直径为 30mm× 长 50mm 的圆柱体，任取其一装入催化反应器中。
催化剂性能评价在固定床流动反应器中进行，以甲苯为挥发性有机物代表物，甲苯由冰水混合物浸浴保温，采用空气鼓泡带出甲苯 - 空气混合物形成模拟废气，其中甲苯含量为 3490±50 mg·m-3 ，反应空速控制为 15000h-1 ，评价装置进出口甲苯的浓度用气相色谱仪 GC2014C 的 FID 进行分析。
甲苯的转化率则用下式进行计算：
甲苯的转化率（ Conv ， % ） =[( 进口甲苯浓度 Conci- 出口甲苯浓度 Conco)/ 进口甲苯浓度 Conci]×100% 。
每个温度下，当催化氧化反应达到稳定状态 5min 后，再进行成分的分析。
本实施例制备的催化剂在 230 ℃ 下， Conci=3490 mg·m-3 ， Conco=30 mg·m-3 ，甲苯的转化率 Conv 为 99.14% 。
本实施例制备的催化剂在 600 ℃ 下连续运行 200h 后，在 255 ℃ 下对甲苯进行催化氧化反应试验，试验结果如下： Conci=3480 mg·m-3 ， Conco=35 mg·m-3 ，甲苯的转化率 Conv 为 98.99% 。
实施例 3
（ 1 ）改性氧化铝在堇青石蜂窝陶瓷基体上的涂覆
将铁盐、钴盐、镍盐的混合溶液与氢氧化铝的水溶性胶体混合，所述的铁、钴、镍盐为 Fe(NO3)3·9H2O 、 Co(AC)3·4H2O 、 Ni(NO3)4·6H2O ，具体是称取 59.8240g Fe(NO3)3·9H2O 、 36.8859g Co(AC)3·4H2O 、 42.6257g Ni(NO3)4·6H2O 溶于 30ml 去离子水，并与含 10ml 去离子水和 49.3404g 氢氧化铝的胶体混合，磁力搅拌；配制得到的混合液中，铁、钴、镍、铝的摩尔比为 2 ： 2 ： 2 ： 4 ；
将堇青石蜂窝陶瓷浸渍于上述盐溶液与胶体的混合液中 30min ，进行改性氧化铝的涂覆，涂覆量占基体质量的 5% ，最后在空气气氛下，于 120 ℃ 干燥 6h 和 700 ℃ 焙烧 1h ， 得到涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 2 ）涂覆了改性氧化铝的堇青石蜂窝陶瓷基体的放电强化预处理
将步骤（ 1 ）中得到的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内，放电条件为大气压下介质厚度 5mm ，电压 20000V ，频率 400Hz ，脉宽 200ns ，强化预处理 10min ，得到经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体。
（ 3 ）活性组分浸渍液的制备
配制钯的活性组分浸渍液，将氯铂酸用去离子水溶解，具体是称取 0.8770g H2PtCl6·6H2O ，溶于 40ml 水，得到铂含量为 8.26 g/L 的活性组分浸渍液。
（ 4 ）活性组分的负载与还原
将步骤（ 2 ）得到的经脉冲介质阻挡放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体浸渍于步骤（ 3 ）得到的活性组分浸渍液中 30min ；然后取出，除去残留于蜂窝陶瓷基体孔道中的浸渍液，在空气气氛下，于 120 ℃ 干燥 6h 和 700 ℃ 焙烧 1h ；最后在 H2/N2 气氛（ H2/N2 =5 ： 95 ， V/V ）中，于 250 ℃ 下还原 2h ，得到以极低含量铂为活性组分的催化剂，其活性组分负载量占基体质量的 0.05% 。
（ 5 ）催化剂的性能评价
将尺寸为 100mm×100mm×50mm 的 Pt/Fe-Co-Ni-O-γ-Al2O3/ 堇青石蜂窝陶瓷切割成四个直径为 30mm× 长 50mm 的圆柱体，任取其一装入催化反应器中。
催化剂性能评价在固定床流动反应器中进行，以甲苯为挥发性有机物代表物。甲苯由冰水混合物浸浴保温，采用空气鼓泡带出甲苯 - 空气混合物形成模拟废气，其中甲苯含量为 3490±50 mg·m-3 ，反应空速控制为 15000h-1 ，评价装置进出口甲苯的浓度用气相色谱仪 GC2014C 的 FID 进行分析。
甲苯的转化率则用下式进行计算：
甲苯的转化率（ Conv ， % ） =[( 进口甲苯浓度 Conci- 出口甲苯浓度 Conco)/ 进口甲苯浓度 Conci]×100% 。
每个温度下，当催化氧化反应达到稳定状态 5min 后，再进行成分的分析。
本实施例制备的催化剂在 230 ℃ 下， Conci=3440 mg·m-3 ， Conco=20 mg·m-3 ，甲苯的转化率 Conv 为 99.71% 。
本实施例制备的催化剂在 700 ℃ 下连续运行 200h 后，在 255 ℃ 下对甲苯进行催化氧化反应试验，试验结果如下： Conci=3460 mg·m-3 ， Conco=30 mg·m-3 ，甲苯的转化率 Conv 为 99.13% 。
从上述的实施例中可以看出，本发明的整体催化剂对以甲苯为代表的挥发性有机物的净化中，在较低温度下，催化活性高；即便在
500~700 ℃的高温条件下连续运行200h后，在255℃下依然保持着对甲苯完全氧化能力。而且本发明的催化剂制备工艺简单，贵金属含量极低，热稳定性高，制作成本低，易于推广，具有广阔的应用前景。

Claims (10)

  1. 一种用于净化挥发性有机物的催化剂，其特征在于，以铁、 钴、镍改性的氧化铝为载体，以堇青石蜂窝陶瓷为基体，以极低含量的铂和钯的混合物为活性组分；改性的氧化铝载体涂覆在堇青石蜂窝陶瓷基体上，活性组分负载在改性的氧化铝载体上；
    所述铂与钯的摩尔比为 0~1 ： 0~9 ，且铂和钯的混合物的量 占基体质量的 0.01%~0.05%；所述载体的量占基体质量的 3%~5% 。
  2. 制备权利要求 1 所述的一种用于净化挥发性有机物的催化剂的方法，其特征在于，包括如下步骤：
    （ 1 ）载体的涂覆：
    将铁盐、钴盐、镍盐的混合溶液与氢氧化铝的水溶性胶体混合，得到溶液与胶体的混合液；将堇青石蜂窝陶瓷浸渍于得到的溶液与胶体的混合液中，取出，空气气氛下干燥、焙烧，得到涂覆了改性氧化铝的堇青石蜂窝陶瓷基体；
    （ 2 ）放电强化预处理：
    将得到的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体置于脉冲介质阻挡放电反应区内，放电强化预处理，得到经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体；
    （ 3 ）活性组分浸渍液的制备：
    将铂的前驱物与钯的前驱物用去离子水溶解，混合，得到活性组分浸渍液；
    （ 4 ）活性组分的负载与还原：
    将步骤（ 2 ）得到的经放电强化预处理的涂覆了改性氧化铝的堇青石蜂窝陶瓷基体浸渍于步骤（ 3 ）得到的活性组分浸渍液中，取出，除去残留于蜂窝陶瓷基体孔道中的浸渍液，空气气氛下干燥、焙烧，最后进行还原，得到所述用于净化挥发性有机物的催化剂。
  3. 根据权利要求 2 所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（ 1 ）中，所述铁盐、钴盐、镍盐的混合溶液的浓度为 2.62~4.64 g/mL ；所述氢氧化铝的水溶性胶体的浓度为 3.25~4.93g/mL 。
  4. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（1）中，所述铁盐、钴盐、镍盐为铁、钴、镍的硝酸盐或醋酸盐；所述溶液与胶体的混合液中，铁、钴、镍和铝的摩尔比为1~2：1~2：1~2：4~7。
  5. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（1）中，所述浸渍的时间为20~30min；所述干燥是在120℃干燥3~6h；所述焙烧是在500~700℃焙烧1~3h。
  6. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（2）中，所述放电强化预处理为：放电条件为大气压下，介质厚度为1mm~5mm，电压为5000~20000V，频率为50~400Hz，脉宽为100~200ns，强化预处理的时间为5~10min。
  7. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（3）中，所述铂的前驱物为氯铂酸；所述钯的前驱物为氯化钯。
  8. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（3）中，所述活性组分浸渍液中，铂与钯的总含量为1.65~8.26 g/L。
  9. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（4）中，所述浸渍的时间为20~30min；所述干燥是在120℃干燥3~6h；所述焙烧是在500~700℃焙烧1~3h。
  10. 根据权利要求2所述的一种用于净化挥发性有机物的催化剂的制备方法，其特征在于，步骤（4）中，所述还原是在H2/N2气氛中，在200~250℃温度下还原2~4h。
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CN115090323B (zh) * 2022-06-30 2024-01-16 宁波方太厨具有限公司 用于净化空气的催化剂、制备方法及净化组件
CN115672314A (zh) * 2022-11-01 2023-02-03 兖矿科技有限公司 一种蜂窝型催化剂及其制备方法和应用
CN115672314B (zh) * 2022-11-01 2024-06-07 山东能源集团有限公司 一种蜂窝型催化剂及其制备方法和应用

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