CN103599779B - A kind of CuO/ZrO 2water gas converting catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a _CuO /ZrO2 water-gas shift catalyst and a preparation method thereof, belonging to the technical field of water-gas shift technology and catalysts. In the invention, copper salt, zirconium salt and urea are dissolved in water to form a mixed solution, and then subjected to hydrothermal treatment, and the hydrothermal product is washed, dried and roasted to obtain a _CuO /ZrO2 water-gas shift catalyst. The preparation method of the present invention is simple and easy, and the prepared _CuO /ZrO2 water gas shift catalyst has the advantages of low activation temperature, high activity, wide activity temperature range, high selectivity and good thermal stability, and is especially suitable for hydrogen-rich reaction gas operating environment.

Description

A kind of CuO/ZrO2 water gas shift catalyst and preparation method thereof

technical field

The invention belongs to the field of water-gas shift technology and catalyst technology, and in particular relates to a _CuO /ZrO2 water-gas shift catalyst and a preparation method thereof.

Background technique

Water-Gas-Shift Reaction (Water-Gas-ShiftReaction, CO+H ₂ O→CO+H ₂ ) is an extremely important reaction process in the chemical industry, and is widely used in the ammonia synthesis and hydrogen production industries that use coal, oil and natural gas as raw materials. In recent years, with the development of vehicle-mounted proton exchange membrane fuel cell (PEMFC) technology, the water-gas shift reaction, as an important link in the PEMFC online hydrogen production system, has once again attracted widespread attention. At present, shift catalysts commonly used in industry mainly include iron-chromium-based high-temperature shift catalysts, copper-zinc-based low-temperature shift catalysts, and cobalt-molybdenum-based wide-temperature sulfur-tolerant shift catalysts. However, these three series of shift catalysts cannot meet the requirements of vehicle-mounted PEMFC due to defects such as large volume, spontaneous combustion in air, and cumbersome pretreatment process. Therefore, the development of new and efficient water-gas shift catalysts and the design and improvement of catalyst preparation methods have become an urgent need for the development of vehicle-mounted fuel cell technology.

Recent studies have shown that CuO/ZrO ₂ catalysts prepared by various methods can exhibit excellent catalytic performance for water gas shift reaction. KoJ.B. et al. (Catal.Lett.2005, 105, 157) first reported the application of CuO/ZrO ₂ catalyst prepared by co-precipitation method in low-temperature water-gas shift reaction, and found that the catalyst exhibited a higher performance than commercial CuO- ZnO-Al ₂ O ₃ catalyst has more excellent catalytic activity. Aguila et al. (Catal.Commun.2008, 9, 2550) prepared CuO/ZrO ₂ water gas shift catalysts supported by monoclinic ZrO ₂ and tetragonal ZrO ₂ by impregnation method. The activity test results showed that the tetragonal ZrO ₂ The catalyst activity of the carrier is better. Ruan Chunxiao et al. (CN201010598698) found that the highly active CuO/ZrO ₂ water-gas shift catalyst can be prepared more easily by the deposition-precipitation method than by the co-precipitation method. However, the above-mentioned preparation methods have disadvantages: (1) ZrO ₂ embeds active CuO particles in the CuO/ZrO ₂ catalyst prepared by the precipitation method, so that part of CuO cannot play a catalytic role. In addition, the catalyst prepared by this method Hard agglomeration easily occurs during the roasting process, resulting in the growth of particle size, which is not conducive to the occurrence of catalytic reactions. (2) The CuO particles on the surface of the CuO/ZrO ₂ catalyst produced by the impregnation method are often unevenly distributed, and high-temperature calcination is likely to cause the sintering and growth of the surface CuO particles, which is also not conducive to the catalytic reaction. (3) Although the CuO particles on the surface of the CuO/ZrO ₂ catalyst prepared by the deposition precipitation method are uniformly distributed, the interaction between CuO and ZrO ₂ is often weak, and it is difficult to maintain good thermal stability during the catalytic reaction. In addition, the preparation process of this method is cumbersome, and the ZrO ₂ carrier needs to be prepared first and then loaded with CuO. The preparation process has disadvantages such as secondary washing and secondary roasting. Therefore, it is necessary to develop a simple and more suitable method to prepare CuO/ZrO ₂ water gas shift catalyst.

Contents of the invention

The object of the present invention is to provide a kind of CuO/ZrO ₂ water-gas shift catalyst and preparation method thereof, the preparation process is simple and easy, the prepared CuO/ZrO ₂ water-gas shift catalyst has low activation temperature, high activity, wide active temperature range, With the advantages of high selectivity and good thermal stability, it is especially suitable for the operating environment of hydrogen-rich reaction gas.

To achieve the above object, the present invention adopts the following technical solutions:

A kind of CuO/ZrO _The preparation method of water gas shift catalyst comprises the steps:

(1) Dissolving soluble copper salt, soluble zirconium salt and urea in deionized water to prepare a mixed solution;

(2) Transfer the mixed solution of step (1) into a hydrothermal kettle, control the hydrothermal temperature to 110-210°C, and the hydrothermal time to 3-24 hours; ℃ drying for 8 hours, and then roasting at 200-500 ℃ for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst.

The soluble copper salt in step (1) is one of copper acetate, copper nitrate and copper chloride.

The soluble zirconium salt described in step (1) is one of zirconium nitrate, zirconyl nitrate, and zirconium oxychloride.

In step (1), the molar ratio of soluble copper salt to soluble zirconium salt is 1:9～9:1; the molar ratio of soluble metal salt (that is, the molar sum of soluble copper salt and soluble zirconium salt) to urea is 1:1～ 1:2.

The present invention reacts soluble copper salts, soluble zirconium salts and urea under hydrothermal conditions, and directly obtains _CuO /ZrO2 composite oxide products by controlling the hydrothermal temperature and hydrothermal time, instead of the ordinary precipitation method. The hydroxide mixture of Cu(OH) ₂ and Zr(OH) ₄ avoids the hard agglomeration of the catalyst during the calcination process. Utilizing the harsh hydrothermal environment, the interaction between CuO-ZrO ₂ is enhanced, which is beneficial to the improvement of thermal stability and water resistance of CuO/ZrO ₂ catalyst. The activity test results show that the catalyst prepared by the method of the present invention exhibits excellent catalytic performance at 200°C, the CO conversion rate can reach 85%, and the CO conversion rate is as high as 92% and 90% at 250°C and 300°C.

The remarkable advantage of the present invention is that: the obtained hydrothermal product is directly in the form of oxide, which avoids the phenomenon of hard agglomeration in the process of the catalyst changing from hydroxide to oxide under roasting conditions. Utilizing the harsh hydrothermal environment, the interaction between CuO-ZrO ₂ is enhanced, which in turn improves the thermal stability and water resistance of the CuO/ZrO ₂ catalyst. The prepared CuO/ZrO ₂ catalyst has low activation temperature, high activity at low temperature, wide active temperature range and good thermal stability, especially suitable for hydrogen-rich fuel cell operating environment, which brings new hope for the development of fuel cell technology. The preparation method of the catalyst is simple and easy, and has broad industrial application prospects.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the CuO/ZrO ₂ water gas shift catalyst in Example 2.

Detailed ways

The present invention will be further described below through examples, but the present invention is not limited to these examples.

Example 1

Disperse _{0.877gCuCl2 ·} 2H2O, _{15.081gZrOCl2 ·} 8H2O and 3.120g urea in 65mL deionized water to prepare a mixed solution [ie n(Cu):n(Zr)=1:9, n(Cu+ Zr):n(urea)=1:1]. The above mixed solution was transferred into a hydrothermal reaction kettle with a volume of 100 mL, the hydrothermal temperature was controlled at 210° C., and the hydrothermal time was 3 hours. The hydrothermal product was washed to remove impurity ions, dried at 120°C for 8 hours, and then calcined at 500°C for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst.

Example 2

Disperse 3.769gCu( _NO3 ) _{2 · 3H2O} , 11.730gZrOCl2 _· 8H2O and 3.744g urea in 65mL deionized water to prepare a mixed solution [ie n(Cu):n(Zr)=3:7, n(Cu+Zr):n(urea)=1:1.5]. The above mixed solution was transferred into a hydrothermal reaction kettle with a volume of 100 mL, and the hydrothermal temperature was controlled at 180° C., and the hydrothermal time was 6 hours. The hydrothermal product was washed to remove impurity ions, dried at 120°C for 8 hours, and then calcined at 400°C for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst. Fig. 1 is the X-ray diffraction pattern of the CuO/ZrO ₂ water gas shift catalyst in Example 2. It can be seen from Fig. 1 that the ZrO 2 in the CuO/ZrO ₂ water gas shift catalyst in Example ₂ has two crystal phases of tetragonal phase and monoclinic phase at the same time. And no diffraction peak of crystal phase CuO was found, indicating that _CuO exists in a highly dispersed state or has been incorporated into the ZrO2 lattice, which may be the reason for the excellent water gas shift catalytic activity of this example.

Example 3

Disperse 5.191gCu(Ac) ₂ 2H ₂ O, 11.162gZr(NO ₃ ) ₄ 5H ₂ O and 4.68g urea in 65mL deionized water to prepare a mixed solution [ie n(Cu):n(Zr)=5 :5, n(Cu+Zr):n(urea)=1:2]. The above mixed solution was transferred into a hydrothermal reaction kettle with a volume of 100 mL, and the hydrothermal temperature was controlled at 150° C., and the hydrothermal time was 24 hours. The hydrothermal product was washed to remove impurity ions, dried at 120°C for 8 hours, and then calcined at 300°C for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst.

Example 4

Disperse 11.307gCu(NO ₃ ) ₂ 3H ₂ O, 1.390gZrO(NO ₃ ) ₂ 2H ₂ O and 3.43g urea in 65mL deionized water to prepare a mixed solution [ie n(Cu):n(Zr)= 9:1, n(Cu+Zr):n(urea)=1:1.1]. The above mixed solution was transferred into a hydrothermal reaction kettle with a volume of 100 mL, and the hydrothermal temperature was controlled to be 110° C., and the hydrothermal time was 3 hours. The hydrothermal product was washed to remove impurity ions, dried at 120°C for 8 hours, and then calcined at 200°C for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst.

activity evaluation

The activity evaluation of the catalyst is carried out in a fixed-bed reactor at normal pressure. The evaluation conditions: the feed gas is a simulated methane reformed gas, and its volume percentage composition is 15% CO, 55% H ₂ , 7% CO ₂ , 23% N ₂ ; the catalyst dosage is 0.5g; the activity test temperature range is 200-300°C; the space velocity is 2000cm ³ g ^-1 h ^-1 , and the steam-gas ratio is 1:1. Before the activity evaluation, the catalyst was first activated under _H2 atmosphere, the activation temperature was 200 °C, and the activation time was 0.5 h.

Represent catalytic activity with CO conversion rate, the activity evaluation result of embodiment is as table 1:

The activity evaluation result of table 1 embodiment

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (5)

1. a _CuO /ZrO preparation method of water gas shift catalyst, is characterized in that: comprise the steps: (1) Dissolving soluble copper salt, soluble zirconium salt and urea in deionized water to prepare a mixed solution; (2) Transfer the mixed solution of step (1) into a hydrothermal kettle, control the hydrothermal temperature to 110-210°C, and the hydrothermal time to 3-24 hours; ℃ drying for 8 hours, and then roasting at 200-500 ℃ for 4 hours to prepare CuO/ZrO ₂ water gas shift catalyst. 2. The preparation method of CuO/ZrO ₂ water gas shift catalyst according to claim 1, characterized in that the soluble copper salt in step (1) is one of copper acetate, copper nitrate and copper chloride. 3. The preparation method of _CuO /ZrO2 water gas shift catalyst according to claim 1, characterized in that: the soluble zirconium salt described in step (1) is one of zirconium nitrate, zirconyl nitrate, and zirconium oxychloride . 4. The preparation method of CuO/ZrO ₂ water gas shift catalyst according to claim 1, characterized in that: the molar ratio of soluble copper salt to soluble zirconium salt in step (1) is 1:9 to 9:1; soluble copper The molar ratio of the sum of salt and soluble zirconium salt to urea is 1:1-1:2. 5. A _CuO /ZrO2 water gas shift catalyst prepared by the method as claimed in claim 1.