Hydrothermal large-cavity high-temperature high-pressure experimental device and experimental method

Abstract

The invention discloses a hydrothermal large-cavity high-temperature high-pressure experimental device and an experimental method. The device comprises a kettle body and a kettle plug, wherein the kettle body is a hexagonal structure and has a sample empty cavity structure in the kettle body; six detachably-sealed kettle plugs are respectively connected to six sides; optical windows are arranged on three horizontally-arranged kettle plugs; a three-electrode sensor is mounted on the remaining horizontally-arranged kettle plug; a thermocouple is arranged on the kettle plug at the upper end of the kettle body; a high-pressure capillary inlet is formed in the kettle plug at the lower end of the kettle body; a heating device is arranged outside the kettle body; and an optical detection device is arranged at the position facing the optical window. The device adopts a detachable kettle plug structure, does not need to manufacture high-pressure kettles with different sizes, only needs to manufacture kettle plugs with different lengths, can control the thickness of a solution in the sample cavity according to the different lengths of the kettle plugs, and effectively solves the technical problem that the thickness of the solution cannot be changed in the prior art.

Description

technical field [0001] The invention belongs to the technical field of high-temperature and high-pressure experimental devices, and in particular relates to a hydrothermal large-cavity high-temperature and high-pressure experimental device and an experimental method. Background technique [0002] The pH value of the high-temperature and high-pressure hydrothermal system is an important physical and chemical parameter of the system, which has an extremely important impact on the composition, structure, properties, and occurrence and development of the system. Therefore, no matter in high-pressure hydrothermal scientific experiments, field detection or such as In the fields of high-pressure hydrothermal material synthesis, high-temperature hydrometallurgy, metal corrosion and protection, chemical industry, supercritical water extraction and oxidation, nuclear energy engineering, etc. Basic work on high-temperature and high-pressure hydrothermal systems and control of high-pres...

AI Technical Summary

Problems solved by technology

[0008] (1) The pure electrochemical measurement method under high temperature and high pressure has the following disadvantages: the description of the reaction mechanism and the determination of kinetic parameters by the electrochemical method are based on current and potential measurements, such as according to current and scan speed, concentration, time or electrode rotation speed The functional relationship of a series of parameters, and then speculate on the reaction mechanism and determine the kinetic parameters. The main disadvantage is that this purely electrical measurement lacks the characteristics of the electrode reaction molecules, that is, the current only represents the total rate of all processes occurring on the electrode surface. , there is no useful direct information about the reaction products or intermediates. In addition, in the study of the electrode / electrolyte solution interface structure, the theoretical value is obtained from the measurement and calculation of the capacitance, and the information cannot be obtained from the molecular level.

Therefore, the three-electrode electrochemical measurement method under high temperature and pressure has certain limitations, for example: it does not have the ability to characterize specific molecules, and cannot adapt to the requirements of in-depth microscopic research. It can provide the sum of various microscopic information of the electrode reaction, but it is difficult to accurately identify the reactants, intermediates and products on the electrode and explain the reaction mechanism

The high-temperature and high-pressure experimental device designed by the predecessors cannot use the three-electrode electrochemical measurement system to perform electrochemical measurements under high temperature and high pressure conditions, and at the same time use synchrotron radiation X-ray spectroscopy to measure the solid products and solutions on the surface of the working electrode under high temperature and high pressure. In situ measurement of material composition, electronic structure and local structure in

[0009] At present, the high-temperature and high-pressure devices that can perform in-situ measurements of synchrotron radiation X-ray spectroscopy cannot use electrochemical methods to study the experimental system, and there are the following problems. When the technology is combined, there are some shortcomings: ①The density of diamond is relatively high (3.52g / cm 3 ), the absorption of X-rays with energy lower than 10keV is relatively heavy. For example, when 8keV X-rays pass through two diamond anvils with a thickness of 2.4mm in the transmission mode, the luminous flux will be reduced by 2 orders of magnitude; ②The diamond anvil is a single crystal, When measuring the absorption spectrum in transmission mode, diamond diffraction peaks will be generated, which seriously interferes with the quality of the absorption spectrum of the test sample

In addition, it is very difficult for HDAC to independently control the two variables of temperature and pressure, and the size of the sample chamber is generally small (~0.2mm 3 ), it is also very difficult to further increase the volume of the sample chamber, so that it is difficult to realize the in-situ monitoring of fluid properties, that is, it is impossible to fully reveal the internal relationship between temperature, pressure, the occurrence form of ore-forming elements, and fluid properties;

[0010] The synchrotron radiation technology combined with hydrothermal large-cavity high-temperature and high-pressure devices is relatively simple. At present, there are only reports on the combination of synchrotron radiation X-ray absorption spectroscopy, synchrotron radiation X-ray absorption spectroscopy and X-ray fluorescence spectroscopy. It is mainly used to measure the electronic structure and local structure of substances in fluids. It is difficult to measure solid substances, and the identification of solid surface products in the process of water-fluid-solid interaction is particularly important, so more testing techniques are required. For more information on solid-liquid reaction processes

[0011] (2) In the process of measuring the X-ray absorption spectrum, due to the difference between the solution concentration and the X-ray intensity, the measurement process may need to measure solutions of different thicknesses, so it is necessary to make pressure vessels with different inner diameters, and the cost is relatively high;

[0012] (3) In the high-temperature and high-pressure experimental devices designed by predecessors, the pressure cannot generally be adjusted independently of the temperature without changing the material composition

Images