WO2019109213A1 - 一种稀土金属和磷协同改性的Al2O3颗粒及其制备方法 - Google Patents

一种稀土金属和磷协同改性的Al2O3颗粒及其制备方法 Download PDF

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WO2019109213A1
WO2019109213A1 PCT/CN2017/114470 CN2017114470W WO2019109213A1 WO 2019109213 A1 WO2019109213 A1 WO 2019109213A1 CN 2017114470 W CN2017114470 W CN 2017114470W WO 2019109213 A1 WO2019109213 A1 WO 2019109213A1
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phosphorus
rare earth
earth metal
source
modified
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PCT/CN2017/114470
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French (fr)
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沈美庆
王军
王建强
董金诗
朱金鑫
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天津大学
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates

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  • the invention relates to the technical field of inorganic advanced micro-nano materials, in particular to the technical field of catalyst carriers.
  • ⁇ -type alumina has excellent surface properties, such as large specific surface area, developed micro-nano pore structure, uniform dispersion of active sites, wide temperature range of crystal phase, and acidity of surface.
  • the requirements for properties and high reactivity are widely used as catalysts and their carriers.
  • activated alumina is prone to sintering and phase transformation, resulting in a significant decrease in specific surface area, resulting in decreased or even deactivated catalyst activity.
  • necessary measures must be taken to increase the phase transition temperature of the activated alumina and improve the stability of the catalyst. Therefore, how to prevent the phase transformation of ⁇ -type alumina and improve its thermal stability is of great significance for prolonging the service life of industrial catalysts.
  • a supported catalyst prepared by using conventional activated alumina as a catalyst carrier has the following disadvantages:
  • a first aspect of the invention relates to a rare earth metal and phosphorus synergistically modified Al 2 O 3 particles, wherein the phosphorus element content is 0.1-10 wt% based on the total weight of the rare earth metal and phosphorus synergistically modified Al 2 O 3 particles %, the rare earth metal element content is 0.1-10% by weight.
  • the mass ratio of the rare earth metal element to the phosphorus element is no limitation.
  • the rare earth metal and phosphorus may be present in various forms.
  • the rare earth metal and phosphorus may be supported on the pore surface of the Al 2 O 3 carrier to form a rare earth metal and phosphorus synergistic surface-modified Al 2 O 3 particle; or
  • the rare earth metal and phosphorus are located in the bulk phase structure of the Al 2 O 3 carrier to form Al 2 O 3 particles modified by the rare earth metal and the phosphorus synergistic phase; or both surface modification and bulk modification exist simultaneously.
  • the rare earth metal includes, but is not limited to, at least one of ruthenium, osmium, iridium, osmium, iridium or osmium.
  • the rare earth metal and phosphorus synergistically modified alumina has a BET specific surface area of from 100 to 500 m 2 /g, a pore volume of from 0.1 to 0.8 m 3 /g, and an average pore diameter of from 1.9 to 10.1 nm.
  • a second aspect of the invention relates to a method for preparing a surface-modified Al 2 O 3 particle of a rare earth metal and phosphorus, comprising the steps of:
  • the phosphorus source and the rare earth metal are loaded onto the ⁇ -Al 2 O 3 , and specifically may include:
  • the phosphorus source and the rare earth metal source are simultaneously or sequentially loaded onto the ⁇ -Al 2 O 3 , or
  • step B The product of step B is calcined at 450-700 ° C to obtain a surface-modified Al 2 O 3 particle of rare earth metal and phosphorus.
  • the rare earth and phosphorus enter the alumina pores in the form of close contact or in the form of a spatial distance, and bond with the aluminum and oxygen atoms of the surface to form a chemical bond.
  • a third aspect of the invention relates to a method for preparing a rare earth metal and phosphorus synergistic phase-modified Al 2 O 3 particle, comprising the steps of:
  • A1 mixing an aluminum source, a rare earth metal source and a phosphorus source in water in proportion, and then adding ammonia water to form an aluminum gel containing a rare earth metal source and a phosphorus source;
  • A2 first adding ammonia water to the aluminum source to form an aluminum gel, and then adding a rare earth metal source and a phosphorus source to the aluminum gel and mixing them uniformly;
  • step A1 or A2 The product of step A1 or A2 is calcined at 450-650 ° C for 1-5 h to obtain Al 2 O 3 particles modified by the rare earth metal and phosphorus synergistic phase.
  • the rare earth metal element ions are filled in the cation defect during the formation of the aluminum gel and the conversion of the aluminum gel into ⁇ -Al 2 O 3 .
  • a perovskite structure is formed in the alumina spinel structure or in the alumina bulk phase; phosphorus exists in the alumina bulk phase as a phosphorous element, an oxide or an Al-OPO-Al structure.
  • the aluminum source is selected from a soluble aluminum salt such as Al(NO 3 ) 3 or AlCl 3
  • the phosphorus source is selected from a soluble phosphate or a hydrogen phosphate such as (NH 4 ) 2 HPO 4
  • the rare earth metal source is selected from the group consisting of soluble salts thereof such as nitrates, hydrochlorides or acetates. It is of course also possible to each be selected from other sources of solubility.
  • a fourth aspect of the invention relates to a catalyst for catalyzing a CO oxidation reaction, a three-way catalytic reaction of an automobile exhaust gas or an oxidative removal reaction of a volatile organic substance, comprising:
  • a carrier which is an Al 2 O 3 particle synergistically modified with a rare earth metal and phosphorus according to the first aspect of the present invention; and an active component supported on the carrier selected from a noble metal or a transition metal nanoparticle;
  • the noble metal or transition metal is in an oxidized state or a single state, and the mass of the noble metal or transition metal is 0.01-6% by mass of the carrier.
  • the Al 2 O 3 particles synergistically modified by the rare earth element and phosphorus can effectively maintain the specific surface and pore structure of ⁇ -Al 2 O 3 at high temperature, and inhibit the high temperature phase transition of alumina, and ⁇ -
  • the alpha phase transition temperature of alumina is increased to above 1200 °C. This greatly enhances its ability to withstand high temperature hydrothermal aging.
  • the relative amount of acid sites and surface alkali sites on the surface of activated alumina and the spatial arrangement can be effectively regulated to meet the surface acid/base demand of different reaction systems.
  • the added phosphorus increases the strong Lewis acid center of the surface while producing a medium-strong The acid center greatly reduces the surface alkalinity of the alumina, and the surface of the sample containing 3-6 wt.% of phosphorus has almost no alkaline center.
  • the addition of the rare earth metal element not only increases the basic position of the alumina surface, but also enhances the surface basic strength of the alumina.
  • the ratio of phosphorus and rare earth elements the surface acid-base characteristics of alumina can be freely adjusted to facilitate catalyst performance adjustment for different reactions.
  • Fig. 1 is a transmission electron microscope (TEM) photograph of ⁇ -alumina particles which have not been synergistically modified with rare earth elements and phosphorus after hydrothermal treatment at 1050 °C. It can be seen from the photograph that the ⁇ -alumina crystal form has been converted into the ⁇ phase.
  • TEM transmission electron microscope
  • TEM 2 is a transmission electron microscope (TEM) photograph of the ⁇ -alumina particles of the rare earth element and phosphorus synergistic surface-modified granules of the present invention after hydrothermal treatment at 1050 ° C. It can be seen from the photograph that after the high temperature hydrothermal treatment at 1050 ° C, the alumina crystal form is still the ⁇ phase.
  • TEM transmission electron microscope
  • Fig. 3 is a transmission electron microscope (TEM) photograph of the ⁇ -alumina particles of the rare earth element and the phosphorus synergistic phase-modified phase of the present invention after hydrothermal treatment at 1050 °C. It can be seen from the photograph that after the high temperature hydrothermal treatment at 1050 ° C, the alumina crystal form is still the ⁇ phase.
  • TEM transmission electron microscope
  • ⁇ -alumina 4 is an unmodified ⁇ -alumina (A), a rare earth element and a phosphorus surface-modified ⁇ -alumina (B), and a rare earth element and a phosphorous phase-modified ⁇ -alumina (C), respectively.
  • Figure 5 is an in situ infrared spectrum of pyridine adsorption of unmodified gamma-alumina.
  • Fig. 6 is an in situ infrared spectrum of pyridine adsorption of rare earth element and phosphorus surface-modified ⁇ -alumina. It can be seen from the figure that the ⁇ -alumina modified by rare earth and phosphorus surface exhibits strong pyridine adsorption infrared signal, which indicates that the surface modification of rare earth elements and phosphorus can greatly improve the surface acidity of ⁇ -alumina.
  • Fig. 7 is a pyridine adsorption in situ infrared spectrum of ⁇ -alumina modified by rare earth elements and phosphorous phases. It can be seen from the figure that the ⁇ -alumina modified by rare earth element and phosphorous phase exhibits strong pyridine adsorption infrared signal, indicating that the modification of rare earth element and phosphorous phase can also improve the surface acidity of ⁇ -alumina. .
  • Figure 8 is an unmodified ⁇ -alumina (a), a rare earth element and a phosphorus surface-modified ⁇ -alumina (b), and a rare earth element and a phosphorous phase-modified ⁇ -alumina (c) CO 2 adsorption-desorption in situ infrared spectrum. It can be seen from the figure that the surface modification and bulk modification of alkaline earth elements and phosphorus can increase the alkalinity of ⁇ -alumina to varying degrees.
  • Figure 9 is the same amount of precious metal Pd supported on unmodified ⁇ -alumina (a), rare earth element and phosphorus surface-modified ⁇ -alumina (b) and modified with rare earth elements and phosphorous phases.
  • the ⁇ -alumina (c) is made into a CO conversion catalyst, it is subjected to high-temperature hydrothermal treatment under the same conditions, and then used again to catalyze the CO conversion rate as a function of the reaction temperature in the CO oxidation reaction. It can be seen from the figure that after high-temperature hydrothermal treatment, the CO conversion rate of the catalyst with ⁇ -alumina synergistically modified by rare earth element and phosphorus is higher than that of the unmodified ⁇ -alumina as a carrier. This indicates that the synergistic modification of rare earth elements and phosphorus improves the stability and lifetime of Pd supported on the ⁇ -alumina catalyst.
  • Figure 10 is the same amount of precious metal Pd supported on unmodified ⁇ -alumina (a), rare earth element and phosphorus surface-modified ⁇ -alumina (b) and modified with rare earth elements and phosphorous phases.
  • ⁇ -alumina (c) is made into a C 3 H 6 conversion catalyst, it is subjected to high-temperature hydrothermal treatment under the same conditions, and then used again to catalyze the conversion of C 3 H 6 with the reaction temperature in the C 3 H 6 oxidation reaction. Relationship lines.
  • the pure ⁇ -type alumina which is not modified by the rare earth element and phosphorus is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O is formulated into a 1 mol/L Al(NO 3 ) 3 solution, and 1:2 (volume ratio) ammonia water is added dropwise to the solution, and stirring is continued;
  • the ⁇ -type alumina C1 in which the rare earth element and phosphorus are synergistically surface-modified is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O is formulated into a 0.1-1.5 mol/L Al(NO 3 ) 3 solution, and 1:1-l:6 (volume ratio) ammonia water is added dropwise to the solution. Stirring continuously, the viscosity of the solution gradually increases. After the thickest point (gel formation point), the ammonia water is continuously added dropwise, the pH of the gel is adjusted to 5.5-7.5, stirred, and allowed to stand at room temperature and then dried to constant weight. 450- in the muffle furnace. Calcination at 600 ° C for 6 h gave pure ⁇ -Al 2 O 3 .
  • the ⁇ -type alumina C2 in which the rare earth element and phosphorus are synergistically surface-modified is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O is formulated into a 0.1-1.5 mol/L Al(NO 3 ) 3 solution, and 1:1-l:6 (volume ratio) ammonia water is added dropwise to the solution. Stirring continuously, the viscosity of the solution gradually increases. After the thickest point (gel formation point), the ammonia water is continuously added dropwise, the pH of the gel is adjusted to 5.5-7.5, and after stirring for 0.5-3 hours, it is allowed to stand at room temperature for 10-30 hours, 60-100 ° C. Dry to constant weight, calcined at 450-600 ° C for 2-6 h in a muffle furnace to obtain pure ⁇ -Al 2 O 3 .
  • the ⁇ -type alumina C3 in which the rare earth element and phosphorus are synergistically surface-modified is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O is formulated into a 0.1-1.5 mol/L Al(NO 3 ) 3 solution, and 1:1-l:6 (volume ratio) ammonia water is added dropwise to the solution. Stirring continuously, the viscosity of the solution gradually increases. After the thickest point (gel formation point), the ammonia water is continuously added dropwise, the pH of the gel is adjusted to 5.5-7.5, and after stirring for 0.5-3 hours, it is allowed to stand at room temperature for 10-30 hours, 60-100 ° C. Dry to constant weight, calcined at 450-600 ° C for 2-6 h in a muffle furnace to obtain pure ⁇ -Al 2 O 3 .
  • the ⁇ -type alumina C4 modified by the rare earth element and the phosphorus synergistic phase is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O is formulated into a 0.1-1.2 mol/L Al(NO 3 ) 3 solution, and 1:1 to 1:6 (volume ratio) ammonia water is added dropwise to the solution. With continuous stirring, the viscosity of the solution gradually increases. After the thickest point, the ammonia water is continuously added dropwise, the gel pH is adjusted to 5-7.5, and the mixture is stirred for 0.5-4 hours.
  • the gel product obtained in the step A is added with an aqueous solution of (NH 4 ) 2 HPO 4 and a rare earth metal soluble salt (nitrate, acetate, chloride), and stirring is continued for 0.5-4 h.
  • a rare earth metal soluble salt nitrate, acetate, chloride
  • the ⁇ -type alumina C5 modified by the rare earth element and the phosphorus synergistic phase is prepared by the following steps:
  • Al(NO 3 ) 3 ⁇ 9H 2 O was formulated into a 0.1-1.2 mol/L Al(NO 3 ) 3 solution.
  • the rare earth metal and phosphorus surface-modified alumina particles C3-2 prepared in Example 10 and the ordinary alumina C0 prepared in the comparative example were respectively loaded with 2% of elemental precious metal Pd of the material mass.
  • the Pd-loaded C3-2 and the Pd-loaded C-0 were subjected to hydrothermal aging treatment under the conditions of hydrothermal aging treatment in an air atmosphere of 1050 ° C and 10% H 2 O for 20 hours. They are then used to catalytically oxidize CO and C 3 H 6 , respectively .
  • the reaction conditions were 0.1% C 3 H 6 , 2% CO, 2% O 2 and carrier gas N 2 ; the gas flow rate was 1 L/min, and the amount of the catalyst was 200 mg.
  • the catalyst was first reduced at 5% H 2 /N 2 at 200 ° C for 30 min before cooling, and then cooled to 200 ° C.
  • the rare earth element and the phosphorous phase-modified alumina particles C5-2 prepared in Example 18 and the ordinary alumina C0 prepared in the comparative example were respectively loaded with 2% of elemental precious metal Pd of the material mass.
  • the Pd-loaded C5-2 and the Pd-loaded C-0 were subjected to hydrothermal aging treatment under the conditions of hydrothermal aging treatment in an air atmosphere of 1050 ° C and 10% H 2 O for 20 hours. They are then used to catalytically oxidize CO and C 3 H 6 , respectively .
  • the reaction conditions were 0.1% C 3 H 6 , 2% CO, 2% O 2 , and a carrier gas N 2 ; a gas flow rate of 1 L/min, and a catalyst amount of 200 mg.
  • the catalyst was first reduced at 5% H 2 /N 2 at 200 ° C for 30 min before cooling, and then cooled to 200 ° C.
  • Table 6 shows the change of BET specific surface area after each sample was subjected to high temperature hydrothermal treatment at 1050 °C.
  • the rare earth element and phosphorus surface modification and the bulk-modified ⁇ -type alumina decrease the BET specific surface area after high-temperature hydrothermal treatment, indicating the modified ⁇ -type oxidation.
  • the stability of the aluminum structure is improved.
  • Table 7 shows the change in the dispersion degree of the noble metal after each sample was loaded as a carrier and subjected to hydrothermal treatment at 1050 °C.
  • the noble metal supported on the rare earth element and the phosphorus-modified ⁇ -type alumina is higher than the precious metal loaded to the unmodified ⁇ -type alumina, and the introduction of rare earth elements and phosphorus can stabilize the precious metal. Reduce the effect of precious metal sintering being embedded.

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Abstract

一种稀土金属和磷协同改性的Al 2O 3颗粒，基于所述稀土金属和磷协同改性的Al 2O 3颗粒的总重量，磷元素含量为0.1-10wt％，稀土金属元素含量为0.1-10wt％。其中，所述稀土金属和磷可以存在于Al 2O 3孔道内或存在于Al 2O 3体相中。还涉及上述稀土金属和磷协同改性的Al 2O 3颗粒的制备方法。又涉及用于的催化剂，其包括负载在上述稀土金属和磷协同改性的Al 2O 3颗粒上的贵金属或过渡金属纳米颗粒。稀土金属和磷协同改性的Al 2O 3颗粒水热稳定性好，活性组分老化后分散显著得到改善，在汽车和工业尾气催化氧化领域具有应用前景。

Description

一种稀土金属和磷协同改性的Al2O3颗粒及其制备方法 技术领域
本发明涉及无机先进微纳米材料技术领域，尤其涉及催化剂载体技术领域。
背景技术
γ型氧化铝具有优良的表面性质，如比表面积大、微纳米孔隙结构发达、活性位分散均匀、晶相温度范围广、表面具有酸性等特性而被称为活性氧化铝，可以满足催化剂高选择性和高反应活性的要求，被广泛用作催化剂及其载体。但在高温反应中，特别是在尾气净化、催化燃烧以及甲烷氧化等高温、含水气氛中，活性氧化铝容易发生烧结和相变，使比表面大幅度下降，导致催化剂活性下降甚至失活。为了保证催化剂的有效使用，必须采取必要的措施提高活性氧化铝的相转变温度，改善催化剂的稳定性。因此，如何阻止γ型氧化铝的相变，提高其热稳定性，对延长工业催化剂的使用寿命具有重要意义。
当应用于高温含有水蒸气等的尾气催化后处理领域时，以常规活性氧化铝作为催化剂载体制备的负载型催化剂具有以下缺点：
1)水热稳定性差：载体本身容易在高温状态下发生烧结及相变，造成比表面积和孔隙率降低；
2)表面酸碱性单一，且不能调控以满足特定反应体系对特定的表面酸碱性需求；
3)所负载的贵金属或过渡金属等活性组分在高温水热老化过程中易被包埋。
因此，如何在维持活性氧化铝载体的高水热稳定性同时又保证其适宜的表面酸碱性等性能已成为目前值得关注的课题。
发明内容
为了解决上述问题，提出本发明。
本发明第一方面涉及一种稀土金属和磷协同改性的Al2O3颗粒，其中基于所述稀土金属和磷协同改性的Al2O3颗粒的总重量，磷元素含量为0.1-10wt％，稀土金属元素含量为0.1-10wt％。对稀土金属元素与磷元素的质量比没有限制。
其中稀土金属和磷的存在形态可以多种多样，例如，稀土金属和磷可以负载于Al2O3载体的孔道表面上，形成稀土金属和磷协同表面改性的Al2O3颗粒；或者，稀土金属和磷位于Al2O3载体的体相结构中，形成稀土金属和磷协同体相改性的Al2O3颗粒；或者表面改性和体相改性同时存在。
其中所述稀土金属包括但不限于镧、铈、镨、钕、镱或钐中的至少一种。
在优选的实施方案中，所述稀土金属和磷协同改性的氧化铝BET比表面积为100-500m2/g，孔体积为0.1-0.8m3/g，平均孔径1.9-10.1nm。
本发明第二方面涉及稀土金属和磷协同表面改性的Al2O3颗粒的制备方法，其包括以下步骤：
A、提供γ-Al2O3，然后
B、将磷源和稀土金属负载到γ-Al2O3上，具体可包括：
B1、将磷源和稀土金属源同时或先后负载到γ-Al2O3上，或
B2、将磷源负载到一部分γ-Al2O3上，同时将稀土金属源负载到另一部分γ-Al2O3上，再将二者混合；然后
C、将步骤B的产物在450-700℃下焙烧，得到稀土金属和磷协同表面改性的Al2O3颗粒。
上述稀土金属和磷协同表面改性的Al2O3颗粒中，稀土和磷以紧密接触的形式或者存在空间距离的形式进入氧化铝孔道中，并与表面的铝和氧原子键合形成化学键。
本发明第三方面涉及稀土金属和磷协同体相改性的Al2O3颗粒的制备方法，其包括以下步骤：
A1、将铝源、稀土金属源和磷源按比例混合在水中，然后加入氨水形成含稀土金属源和磷源的铝凝胶；或者，
A2、先向铝源中加入氨水形成铝凝胶，然后再向铝凝胶中加入稀土金属源和磷源并混合均匀；然后，
B、将步骤A1或A2的产物在450-650℃下煅烧1-5h，得到稀土金属和磷协同体相改性的Al2O3颗粒。
上述稀土金属和磷协同体相改性的Al2O3颗粒中，稀土金属元素离子在铝凝胶形成过程中以及铝凝胶转变为γ-Al2O3的过程中，填充在阳离子缺陷的氧化铝尖晶石结构中或者在氧化铝体相中形成钙钛矿结构；磷在氧化铝体相以磷单质、氧化物或Al-O-P-O-Al结构形式存在。
优选地，上述制备方法中，所述铝源选自可溶性铝盐例如Al(NO3)3或AlCl3，所述磷源选自可溶性磷酸盐或磷酸氢盐例如(NH4)2HPO4，所述稀土金属源选自其可溶性盐例如硝酸盐、盐酸盐或乙酸盐。当然也可以各自选自其他可溶性源。
本发明第四方面涉及一种用于催化CO氧化反应、汽车尾气三效催化反应或挥发性有机物氧化脱除反应的催化剂，其包括：
载体，其为根据本发明第一方面所述的稀土金属和磷协同改性的Al2O3颗粒；和负载在该载体上的活性组分，其选自贵金属或过渡金属纳米颗粒；其中所述贵金属或过渡金属呈氧化态或单质态，且所述贵金属或过渡金属的质量为所述载体质量的0.01-6％。
本发明的有益效果如下：
1、所述稀土元素和磷协同改性的Al2O3颗粒，在高温下仍能有效保持γ-Al2O3的比表面和孔结构，且抑制了氧化铝的高温相变，将γ-氧化铝的α相变温度提高至1200℃以上。这大大提高了其抗高温水热老化的能力。
2、稀土元素和磷协同改性后，可以有效调控活性氧化铝表面的酸位点和表面碱位点的相对数量以及空间排布，满足不同反应体系对表面酸/碱的需求。加入的磷增加了表面的强Lewis酸中心，同时产生了中强的
Figure PCTCN2017114470-appb-000001
酸中心；大幅降低了氧化铝的表面碱性，含磷3-6wt.％的样品表面几乎不存在碱性中心。相反稀土金属元素的加入不但增加了氧化铝表面的碱性位，而且增强了氧化铝的表面碱性强度。通过调整磷和稀土元素的比例，可以自由调节氧化铝的表面酸碱性特征，便于针对不同的反应进行催化剂性能调整。
附图说明
图1是没有未经稀土元素和磷协同改性的γ-氧化铝颗粒在1050℃下水热处理后的透射电子显微镜(TEM)照片。从照片上可以看出γ-氧化铝晶型已转变为θ相。
图2是为本发明的稀土元素和磷协同表面改性的γ-氧化铝颗粒在1050℃下水热处理后的透射电子显微镜(TEM)照片。从照片上可以看出，经过1050℃高温水热处理后，氧化铝晶型仍为γ相。
图3是本发明的稀土元素和磷协同体相改性的γ-氧化铝颗粒在1050℃下水热处理后的透射电子显微镜(TEM)照片。从照片上可以看出，经过1050℃高温水热处理后，氧化铝晶型仍为γ相。
图4为未经改性的γ-氧化铝(A)、稀土元素和磷表面改性的γ-氧化铝(B)以及稀土元素和磷体相改性的γ-氧化铝(C)分别在1050℃下水热处理后的X-射线衍射(XRD)图。从图中可以看出，经过高温水热处理，未经改性的γ-氧化铝已经出现α和θ相；稀土元素和磷表面改性的γ-氧化铝出现θ相；稀土元素和磷体相改性的γ-氧化铝仅出现δ相。稀土元素和磷表面改性以及体相改性显著提高了γ-氧化铝的相转变温度。
图5是未改性的γ-氧化铝的吡啶吸附原位红外谱图。
图6是稀土元素和磷表面改性的γ-氧化铝的吡啶吸附原位红外谱图。从图中可以看出，经稀土和磷表面改性的γ-氧化铝表现出强的吡啶吸附红外信号，这表明稀土元素和磷表面改性可以大幅提高γ-氧化铝的表面酸性。
图7是稀土元素和磷体相改性的γ-氧化铝的吡啶吸附原位红外谱图。从图中可以看出，经过稀土元素和磷体相改性的γ-氧化铝表现出较强的吡啶吸附红外信号，说明稀土元素和磷体相改性同样可以改善γ-氧化铝的表面酸性。
图8为未经改性的γ-氧化铝(a)、稀土元素和磷表面改性的γ-氧化铝(b)以及稀土元素和磷体相改性的γ-氧化铝(c)的CO2吸附-脱附原位红外谱图。从图中可以看出，碱土元素和磷表面改性和体相改性可以不同程度地提高γ-氧化铝的碱性。
图9为将相同量的贵金属Pd分别负载在未经改性的γ-氧化铝(a)、稀土元素和磷表面改性的γ-氧化铝(b)以及稀土元素和磷体相改性的γ-氧化铝(c)制成CO转化催化剂之后，再经过相同条件下的高温水热处理，然后再次用于催化CO氧化反应时的CO转化率随反应温度的关系曲线。从图中可以看出，经过高温水热处理后，稀土元素和磷协同改性的γ-氧化铝作为载体的催化剂上CO转化率均高于未经改性的γ-氧化铝作为载体的催化剂。这说明稀土元素和磷协同改性提高了Pd负载于γ-氧化铝催化剂的稳定性以及寿命。
图10为将相同量的贵金属Pd分别负载在未经改性的γ-氧化铝(a)、稀土元素和磷表面改性的γ-氧化铝(b)以及稀土元素和磷体相改性的γ-氧化铝(c)制成C3H6转化催化剂之后，再经过相同条件下的高温水热处理，然后再次用于催化C3H6氧化反应时的C3H6转化率随反应温度的关系曲线。从图中可以看出，经过高温水热处理后，稀土元素和磷协同改性的γ-氧化铝作为载体的催化剂上C3H6转化率均高于未经改性的γ-氧化铝作为载体的催化剂。
具体实施方式
给出以下实施例以举例说明本发明，这些实施例并非限制性的。
对比例
通过以下步骤制备未经稀土元素和磷协同改性的纯γ型氧化铝：
A.将Al(NO3)3·9H2O配制成1mol/L的Al(NO3)3溶液，向该溶液中逐滴加入1:2(体积比)氨水，持续搅拌；
B.溶液粘度逐渐增加，至最稠点(凝胶形成点)后继续滴加氨水，调节凝胶pH至6，搅拌2h；
C.室温静置20h，100℃干燥至恒重，马弗炉中550℃煅烧6h，得到纯γ-Al2O3。
实施例1-4
通过以下步骤制备稀土元素和磷协同表面改性的γ型氧化铝C1：
A.将Al(NO3)3·9H2O配制成0.1-1.5mol/L的Al(NO3)3溶液，向该溶液中逐滴加入1:1-l:6(体积比)氨水，持续搅拌，溶液粘度逐渐增加，至最稠点(凝胶形成点)后继续滴加氨水，调节凝胶pH至5.5-7.5，搅拌、室温静置后干燥至恒重，马弗炉中450-600℃煅烧6h，得到纯γ-Al2O3。
B.测量该氧化铝的饱和吸水量。按照饱和吸水量配制不同浓度的(NH4)2HPO4溶液和稀土金属可溶性盐(硝酸盐、醋酸盐、氯化物)水溶液，并将两者混合均匀，加入到γ-A12O3，得到的样品负载量范围为0.1-10wt％。
C.在室温下静置10-30h，80-120℃干燥过夜后在450-700℃马弗炉中焙烧2-6h，得到稀土元素和磷表面改性的氧化铝样品。
具体制备过程工艺条件如下表1所示：
表1
Figure PCTCN2017114470-appb-000002
实施例5-8
通过以下步骤制备稀土元素和磷协同表面改性的γ型氧化铝C2：
A.将Al(NO3)3·9H2O配制成0.1-1.5mol/L的Al(NO3)3溶液，向该溶液中逐滴加入1:1-l:6(体积比)氨水，持续搅拌，溶液粘度逐渐增加，至最稠点(凝胶形成点)后继续滴加氨水，调节凝胶pH至5.5-7.5，搅拌0.5-3h后，室温静置10-30h，60-100℃干燥至恒重，马弗炉中450-600℃煅烧2-6h，得到纯γ-Al2O3。
B.测量该氧化铝的饱和吸水量。按照饱和吸水量配制不同浓度的(NH4)2HPO4溶液加入到γ-A12O3，得到的样品负载量范围为0.1-10wt％。
C.在室温下静置10-30h，80-120℃干燥过夜后，得到磷改性的氧化铝前驱体样品。
D.按照氧化铝饱和吸水量配制不同浓度的稀土金属可溶性盐(硝酸盐、醋酸盐、氯化物)水溶液加入到γ-A12O3，得到的样品负载量范围为0.1-10wt％。
E.在室温下静置10-30h，80-120℃干燥过夜后，得到稀土改性的氧化铝前驱体样品。
F.将上述两种前驱体样品充分研磨混合均匀，置于450-700℃马弗炉中焙烧2-6h，得到稀土-磷表面修饰氧化铝样品。
具体制备过程工艺条件如下表2所示：
表2
Figure PCTCN2017114470-appb-000003
实施例9-12
通过以下步骤制备稀土元素和磷协同表面改性的γ型氧化铝C3：
A.将Al(NO3)3·9H2O配制成0.1-1.5mol/L的Al(NO3)3溶液，向该溶液中逐滴加入1:1-l:6(体积比)氨水，持续搅拌，溶液粘度逐渐增加，至最稠点(凝胶形成点)后继续滴加氨水，调节凝胶pH至5.5-7.5，搅拌0.5-3h后，室温静置10-30h，60-100℃干燥至恒重，马弗炉中450-600℃煅烧2-6h，得到纯γ-Al2O3。
B.测量该氧化铝的饱和吸水量。按照饱和吸水量配制不同浓度的(NH4)2HPO4溶液加入到γ-A12O3，得到的样品的磷负载量范围为0.1-10wt％。
C.在室温下静置10-30h，80-120℃干燥过夜后，得到磷改性的氧化铝前驱体样品。
D.测量该前驱体样品的饱和吸水量。按照该饱和吸水量配制不同浓度的稀土金属可溶性 盐(硝酸盐、醋酸盐、氯化物)水溶液加入到磷改性的氧化铝前驱体样品中，得到的样品中稀土金属元素的负载量范围为0.1-10wt％。
E.在室温下静置10-30h，80-120℃干燥过夜后，置于450-700℃马弗炉中焙烧2-6h，得到稀土元素和磷协同表面改性的氧化铝样品。
具体制备过程工艺条件如下表3所示：
表3
Figure PCTCN2017114470-appb-000004
实施例13-16
通过以下步骤制备稀土元素和磷协同体相改性的γ型氧化铝C4：
A.将Al(NO3)3·9H2O配制成0.1-1.2mol/L的Al(NO3)3溶液，向该溶液中逐滴加入1:1-1:6(体积比)氨水，持续搅拌，溶液粘度逐渐增加，至最稠点后继续滴加氨水，调节凝胶pH至5-7.5，搅拌0.5-4h。
B.步骤A得到的凝胶产物中加入(NH4)2HPO4溶液和稀土金属可溶性盐(硝酸盐、醋酸盐、氯化物)水溶液，继续搅拌0.5-4h。
C.室温静置20-30h，60-90℃干燥至恒重，马弗炉中450-650℃煅烧1-5h。
具体制备过程工艺条件如下表4所示：
表4
Figure PCTCN2017114470-appb-000005
实施例17-20
通过以下步骤制备稀土元素和磷协同体相改性的γ型氧化铝C5：
A.将Al(NO3)3·9H2O配制成0.1-1.2mol/L的Al(NO3)3溶液。
B.向该溶液中逐滴加入1:1-1:6(体积比)氨水，同时逐滴加入(NH4)2HPO4溶液和稀土金属可溶性盐(硝酸盐、醋酸盐、氯化物)水溶液。
C.持续搅拌，溶液粘度逐渐增加，至最稠点后继续滴加氨水，调节凝胶pH至5-7.5，搅拌0.5-4h。
D.室温静置20-30h，60-90℃干燥至恒重，马弗炉中450-650℃煅烧1-5h。
具体制备过程工艺条件如下表5所示：
表5
Figure PCTCN2017114470-appb-000006
实施例21
将在实例中10中制备的稀土金属和磷表面改性的氧化铝颗粒C3-2和在对比例中制备的普通氧化铝C0，分别负载材料质量的2％的单质态贵金属Pd。将负载了Pd的C3-2和负载了Pd的C-0分别进行水热老化处理，条件为在1050℃、10％H2O的空气气氛中水热老化处理20小时。然后分别用于催化氧化CO和C3H6。反应条件为0.1％C3H6,2％CO，2％O2及载气N2；气体流量1L/min，催化剂用量200mg。催化剂评价前先在5％H2/N2，200℃条件下还原30min，然后降温至200℃。
实施例22
将在实例中18中制备的稀土元素和磷体相改性的氧化铝颗粒C5-2和在对比例中制备的普通氧化铝C0，分别负载材料质量的2％的单质态贵金属Pd。将负载了Pd的C5-2和负载了Pd的C-0分别进行水热老化处理，条件为在1050℃、10％H2O的空气气氛中水热老化处理20小时。然后分别用于催化氧化CO和C3H6。反应条件为0.1％C3H6，2％CO，2％O2，以及载气N2；气体流量1L/min，催化剂用量200mg。催化剂评价前先在5％H2/N2，200℃条件下还原30min，然后降温至200℃。
表6为各样品经过1050℃高温水热处理后BET比表面积的变化情况。
表6
Figure PCTCN2017114470-appb-000007
相比于未改性的γ型氧化铝，稀土元素和磷表面改性以及体相改性的γ型氧化铝经过高温水热处理后BET比表面积下降程度减小，说明改性后的γ型氧化铝结构稳定性得到改善。
表7是各样品作为载体负载贵金属并经过1050℃水热处理后，贵金属分散度变化情况。
表7
Figure PCTCN2017114470-appb-000008
在经过高温水热处理后，贵金属负载到稀土元素和磷改性γ型氧化铝上的贵金属分散度均高于贵金属负载到未改性γ型氧化铝，稀土元素和磷的引入可以起到稳定贵金属减少贵金属烧结被包埋的作用。

Claims (8)

  1. 一种稀土金属和磷协同改性的Al2O3颗粒，其特征在于，基于所述稀土金属和磷协同改性的Al2O3颗粒的总重量，磷元素含量为0.1-10wt％，稀土金属元素含量为0.1-10wt％。
  2. 根据权利要求1所述的稀土金属和磷协同改性的Al2O3颗粒，其特征在于，其中稀土金属和磷负载于Al2O3载体的孔道表面上，形成稀土金属和磷协同表面改性的Al2O3颗粒。
  3. 根据权利要求1所述的稀土金属和磷协同改性的Al2O3颗粒，其特征在于，其中稀土金属和磷位于Al2O3载体的体相结构中，形成稀土金属和磷协同体相改性的Al2O3颗粒。
  4. 根据权利要求1所述的稀土金属和磷协同改性的Al2O3颗粒，其特征在于，其中所述稀土金属选自镧、铈、镨、钕、镱或钐中的至少一种。
  5. 根据权利要求2所述的稀土金属和磷协同改性的Al2O3颗粒的制备方法，其包括以下步骤：
    A、提供γ-Al2O3，然后
    B、将磷源和稀土金属负载到γ-Al2O3上，具体可包括：
    B1、将磷源和稀土金属源同时或先后负载到γ-Al2O3上，或
    B2、将磷源负载到一部分γ-Al2O3上，同时将稀土金属源负载到另一部分γ-Al2O3上，再将二者混合；然后
    C、将步骤B的产物静置10-30h后干燥，然后在450-700℃下焙烧，得到稀土金属和磷协同表面改性的Al2O3颗粒。
  6. 根据权利要求3所述的稀土金属和磷协同改性的Al2O3颗粒的制备方法，其包括以下步骤：
    A1、将铝源、稀土金属源和磷源按比例混合在水中，然后加入氨水形成含稀土金属源和磷源的铝凝胶；或者，
    A2、先向铝源中加入氨水形成Al凝胶，然后再向铝凝胶中加入稀土金属源和磷源并混合均匀；然后，
    B、将步骤A1或A2的产物静置10-30h后干燥，然后在450-650℃下煅烧1-5h，得到稀土金属和磷协同体相改性的Al2O3颗粒。
  7. 根据权利要求5或6所述的制备方法，其特征在于，其中所述铝源选自可 溶性铝盐例如Al(NO3)3，所述磷源选自可溶性磷酸盐或磷酸氢盐例如(NH4)2HPO4，所述稀土金属源选自其可溶性盐例如硝酸盐、盐酸盐或乙酸盐。
  8. 一种用于催化NO氧化反应、CO氧化反应、汽车尾气三效催化反应或挥发性有机物氧化脱除反应的催化剂，其包括：
    载体，其为根据权利要求1所述的稀土金属和磷协同改性的Al2O3颗粒；和
    负载在该载体上的活性组分，其选自贵金属或过渡金属纳米颗粒；其中所述贵金属或过渡金属呈氧化态或单质态，且所述贵金属或过渡金属的质量为所述载体质量的0.01-6％。
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JP2012215551A (ja) * 2011-12-22 2012-11-08 Tokyo Univ Of Agriculture 放射性セシウム、ストロンチウムおよびヨード化合物のフィルター型捕集材および捕集方法
CN103204527A (zh) * 2013-03-22 2013-07-17 清华大学深圳研究生院 一种γ-氧化铝颗粒及其制备方法
CN108187705A (zh) * 2017-12-04 2018-06-22 天津大学 一种稀土金属和磷协同改性的Al2O3颗粒及其制备方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117414818A (zh) * 2023-12-12 2024-01-19 淄博恒亿化工科技有限公司 一种改性活性氧化铝及其制备方法
CN117414818B (zh) * 2023-12-12 2024-02-23 淄博恒亿化工科技有限公司 一种改性活性氧化铝及其制备方法

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