CN111646870A

CN111646870A - Catalyst applied to low-temperature starting monopropellant and preparation method thereof

Info

Publication number: CN111646870A
Application number: CN202010379656.4A
Authority: CN
Inventors: 王青; 罗玉宏; 梁竞华
Original assignee: Beijing Institute of Aerospace Testing Technology
Current assignee: Beijing Institute of Aerospace Testing Technology
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2020-09-11

Abstract

The invention relates to a catalyst applied to a single-component propellant started at a low temperature and a preparation method thereof, and mainly solves the problem that a pore channel is broken due to micro-explosion caused by low initial activity of the catalyst when the conventional catalyst is started at a low temperature by a hydrazine-based propellant. The catalyst is prepared by loading two noble metals on a high-strength alumina carrier with a multidimensional pore structure. The catalytic activity of the catalyst under low temperature is improved by utilizing the synergistic effect of the noble metals. The applicable catalytic decomposition reaction temperature of the catalyst is-55-100 ℃.

Description

Catalyst applied to low-temperature starting monopropellant and preparation method thereof

Technical Field

The invention relates to the technical field of catalyst application, in particular to a catalyst for low-temperature starting of a hydrazine-based single-component propellant and a preparation method thereof.

Background

The single-component liquid propulsion system has the characteristics of simple system, high reliability and the like, is widely applied to the aerospace propulsion system, and can be used for speed regulation, orbit entering, fixed point control, attitude control and the like of aerospace vehicles. At present, most of carrier rocket auxiliary power systems adopt single-component propulsion systems, and the key for realizing the normal work of the propulsion systems is that single-component propellants are stably and efficiently decomposed under the action of catalysts. Since the last 60 s, Shell405 catalysts for the catalytic decomposition of hydrazine-based propellants were developed by Shell corporation in the United states and successfully applied to various small-sized attitude control engines. After the United states, the English, French, Germany, Japan, etc. developed Ir/Al2O3 catalysts, such as KCIRGA in Germany, CNESRO-1 in France, and RPE72/1 in British. Hydrazine decomposition catalysts are developed in China from the last 60 years, and then series of hydrazine decomposition catalysts such as 812, 814, 816, 818 and 819 are successfully developed and used in various satellites and other aerospace craft in China.

With the propulsion of tasks such as deep space exploration and the like, aerospace power systems including satellites, carrier rocket ships and other spacecrafts are required to have applicability to work under low-temperature harsh environmental conditions, and higher requirements are provided for rapid starting of propellants at low temperature. In view of the existing hydrazine decomposition catalyst, researchers have studied the temperature sensitivity of the catalyst activity by various methods. In 1968, an engine test is adopted in an American jet laboratory to research the influence of the temperature of a catalyst bed on the activation performance of the catalyst, the test temperature is from-42 ℃ to 35 ℃, the ignition delay period is increased along with the reduction of the temperature of the catalyst bed, and the ignition delay period is 5ms when the bed temperature is 19 ℃; the ignition delay period is 300ms when the bed temperature is-8 ℃. In the last 80 th century, 40N engines and 816 catalysts were used domestically to perform cold-hot start comparative decomposition tests on DT-3 propellants. The 1# engine is cold started for 21 times, the catalyst is broken by 9.1%, the room pressure is reduced by 8.4%, and the flow resistance of the bed is increased by 60.9%. And the 2# and 3# engines are subjected to 1249 times of continuous hot start, which is 60 times of the 1# engine cold start, the catalyst damage is only 6.7%, the chamber pressure is reduced by 4.6% on average, and the bed flow resistance is increased by 45.1% on average. In the last 90 years, 200N thrust chambers are adopted in China, domestic 816 and 814 catalysts are filled in various proportions, H-70 hydrazine water propellant is decomposed at low temperature, H70 cannot successfully realize low-temperature starting at the temperature of below-30 ℃, the initial decomposition time of H70 is a variable function related to temperature at the temperature of between-18 ℃ and-26 ℃, and the lower the temperature is, the longer the initial decomposition time is.

In recent years, people mainly improve the low-temperature starting performance of a propulsion system by optimizing the structure of an engine, such as adopting a heating and heat-insulating device to increase the temperature of a catalytic bed, designing an injector buffer device to reduce the amount of a propellant entering the catalytic bed, prolonging the contact time of the propellant and the catalyst and the like. However, these improved methods of engine construction result in complicated propulsion systems and reduced payload. Especially for the shaped engine, the cost of structural change is high.

The invention aims at several novel low-temperature starting single-component hydrazine-based propellants, and develops a catalyst for the low-temperature starting single-component hydrazine-based propellant in a targeted manner, so that the low-temperature starting performance of the hydrazine-based catalyst is fundamentally improved.

The invention content is as follows:

the invention aims to provide a catalyst for a low-freezing-point mono-component hydrazine-based propellant and a preparation method thereof, aiming at the problem of low-temperature activity of the existing hydrazine decomposition catalyst in the background technology.

The invention can solve the problems by the following technical scheme:

(1) impregnating chloroiridic acid on the carrier, and carrying out low-temperature freeze drying and roasting on the sample.

(2) Alternately dipping chloroauric acid or chloroplatinic acid or rhodium chloride or ruthenium chloride, freezing for 0.5-2h by liquid nitrogen, freeze-drying for 4-24h, roasting for 0.5-4h at the temperature of 200-600 ℃, repeating the steps (1) - (2) until the loading amount reaches 5-40 wt.%, stopping the dipping process, and obtaining the target catalyst after reduction and stabilization treatment.

The invention has the beneficial effects that:

(1) the multidimensional pore channel structure of the catalyst is beneficial to the rapid flow and diffusion of the propellant and decomposition products in the pore channel at low temperature, avoids the crushing of the catalyst caused by the aggregation of decomposition gas, reduces the working performance, and is suitable for the low-temperature start of the monopropellant at the temperature of minus 10 ℃ to minus 55 ℃.

(2) The bimetallic formula of the catalyst utilizes the synergistic effect of bimetallic, has high catalytic activity under the low temperature condition, and is suitable for the low-temperature start of single-component propellant at the temperature of-10 ℃ to-55 ℃.

Description of the drawings:

is free of

The specific implementation mode is as follows:

example 1

(1) The alumina carrier with the strength of 35MPa, the specific surface of 220m2/g, the bulk density of 0.8g/cm3 and the pore structure of 0-2nm, 2-6nm and 100-150nm is soaked in chloroiridic acid, and is frozen for 0.5h at low temperature by liquid nitrogen, freeze-dried for 6h and roasted for 2h at 500 ℃.

(2) Alternately dipping the chlorinated nails, freezing for 0.5h at low temperature by liquid nitrogen, freeze-drying for 6h, roasting for 2h at 500 ℃, repeating the steps (1) to (2) until the load reaches 25%, stopping the dipping process, and obtaining the target catalyst after reduction and stabilization treatment.

Example 2

(1) The strength is 38MPa, the specific surface is 200m²G, bulk density of 0.7g/cm³Alumina carrier with pore structure of 0-2nm, 2-8nm and 100-200nm is soaked in chloroiridic acid, and then frozen at low temperature for 1h by liquid nitrogen, freeze-dried for 8h and roasted for 2h at 500 ℃.

(2) Alternately dipping rhodium chloride, freezing for 1h at low temperature by liquid nitrogen, freeze-drying for 4h, roasting for 2h at 500 ℃, repeating the steps (1) - (2) until the loading capacity reaches 30%, stopping the dipping process, and obtaining the target catalyst after reduction and stabilization treatment.

Example 3

(1) At a strength of 50MPa and a specific surface of 150m²G, bulk density of 0.8g/cm³Alumina carrier with pore structure of 0-2nm, 3-7nm and 150-200nm is soaked in chloroiridic acid, and then frozen at low temperature for 1h by liquid nitrogen, freeze-dried for 8h and roasted for 2h at 400 ℃.

(2) Alternately dipping rhodium chloride, freezing for 1h at low temperature by liquid nitrogen, freeze-drying for 4h, roasting for 2h at 400 ℃, repeating the steps (1) - (2) until the load reaches 38%, stopping the dipping process, and obtaining the target catalyst after reduction and stabilization treatment.

Claims

1. A preparation method of a catalyst applied to a single-component propellant started at low temperature is characterized in that two noble metals A, B are loaded on a high-strength alumina carrier with a multidimensional pore structure. The method mainly comprises the following steps:

(1) and (3) soaking the noble metal precursor A on the carrier, and carrying out low-temperature freeze drying and roasting on the sample.

(2) Alternately dipping the noble metal precursor B, roasting after freeze drying, repeating the steps (1) to (2) until the load reaches the target, stopping the dipping process, and obtaining the target catalyst after reduction and stabilization treatment.

2. According to claimThe alumina carrier with high strength and multidimensional pore structure as in claim 1 is characterized in that the multidimensional pore structure is a three-level pore structure with 0-2nm, 2-10nm and 100-500nm, and the specific surface area is 100-300m²The carrier bulk density is 0.6-1.0g/cm³。

3. The high strength multi-dimensional pore structure oxide support according to claim 1, characterized in that the high strength is 30 to 100 MPa.

4. The two noble metal precursors A, B of claim 1, wherein the noble metal precursor A is chloroiridic acid. The noble metal precursor B is chloroauric acid or chloroplatinic acid or rhodium chloride or chlorinated nails.

5. The freeze-drying method of claim 1, wherein the freeze-drying method comprises freeze-drying for 4-24 hours after freezing for 0.5-2 hours by liquid nitrogen.

6. The calcination according to claim 1 is calcination at a temperature in the range of 200-600 ℃ for 0.5-4 h.

7. The loading target according to claim 1 is 5-40 wt.%.