RU2806143C1 - FLOW MODULAR CONFIGURABLE CELL COMPATIBLE WITH MICROFLUIDIC SYSTEM, FOR CARRYING OUT CHEMICAL REACTION OF METHANE-METHANOL SYNTHESIS ON GOLD/PLATINUM/RUTHENIUM NANOPARTICLES AND IN SITU/IN OPERANDO DIAGNOSTICS OF PROCESS, CARRIED OUT BY X-RAY AND OPTICAL METHODS “ИК”-UV-Vis, XAS, XRD, SAXS, AND THE WAY TO MAKE IT - Google Patents

Abstract

FIELD: analysis of the structure of materials.

SUBSTANCE: invention relates to the field of analysis of the structure of materials under controlled conditions when carrying out homo- and heterogeneous reactions in the liquid phase, including in aggressive environments with low pH, high pressure up to 200 atm and temperatures up to 200°C. A modular flow cell is proposed for carrying out a chemical synthesis reaction, containing a clamping coupling made of steel “07Х18Н13М2”, cylindrical in shape with a thread on its outer surface, onto which a clamping nut made of steel “07Х18Н13М2” is screwed. Between the clamping coupling and the clamping nut there is a cylindrical body with a protrusion, made of steel “07Х18Н13М2”, on which two through holes are made, into which the tubes are rigidly installed. The body is inserted into a clamping coupling made of a cylindrical shape with a thread on its outer surface, and a window made in the form of a hollow cylinder is installed on the body, the diameter of the said window is equal to the outer diameter of the body, and the said window is made of a material transparent in a certain region of the spectrum. Also, a fluoroplastic sealing ring is installed between the window and the body, the diameter of the said ring is equal to the outer diameter of the body, and a microfluidic chip is installed on the body protrusion coaxially with its holes.

EFFECT: development of a modular flow cell to carry out chemical reactions with the ability to perform spectral diagnostics of the nature of the reaction in situ and in operando using “ИК”-UV-Vis, XAS, XRD, SAXS methods on synchrotron radiation sources.

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Description

The invention relates to the field of analyzing the structure of materials under controlled conditions using X-ray sources and to a method for manufacturing a flow-through modular configurable cell for carrying out homo- and heterogeneous reactions in the liquid phase, including in aggressive environments with low pH, high pressure up to 200 atm and temperatures up to 200°C with the possibility of in situ and in operando spectral diagnostics of the nature of the reaction using IR-UV-Vis, XAS, XRD, SAXS methods on synchrotron radiation sources.

It is a compact research chemical reactor, which is used in the field of physical chemistry, conducts research using synchrotron techniques, and is distinguished by the fact that it can withstand high temperatures and pressures, while being microfluidic.

The technical result consists in analyzing the structure of materials under controlled conditions using X-ray sources using a flow-through modular configurable cell and a method for manufacturing a flow-through modular configurable cell for carrying out homo- and heterogeneous reactions in the liquid phase, including in aggressive environments with low pH, high pressure up to 200 atm and temperatures up to 200°C with the possibility of in situ and in operando spectral diagnostics of the nature of the reaction using IR-UV-Vis, XAS, XRD, SAXS methods on synchrotron radiation sources.

State of the art

The closest analogues for the claimed invention are the following patents: KR2020002926 2 (A) dated 2020.03.18 “X-Electrochemical flow cell system for in-situ/operando X-ray absorption spectroscopy using the flow cell and electrode structure used in the flow cell” , also RU 173869 “Cell for laboratory X-ray spectral diagnostics” and RU 190702 “Cell for spectral diagnostics”. But none of them has the important qualities that are inherent in the claimed invention - the ability to withstand high temperatures and pressures, while being microfluidic, namely with the ability to carry out in situ and in operando spectral diagnostics of the nature of the reaction using IR-UV-Vis, XAS methods , XRD, SAXS on synchrotron radiation sources in aggressive environments with low pH, high pressure up to 200 atm and temperatures up to 200°C.

The following illustrations clearly demonstrate the invention:

Fig. 1 - General diagram of a cell module equipped with a window, where 1 - a clamping nut, 2 - a sapphire window, 3 - a microfluidic chip, 4 - a fluoroplastic sealing ring, 5 - a screw clamping coupling, 6 - a cell body, 7 - connecting fittings.

Fig. 2 - Microfluidic geometric patterns “T-junction” and “Flow-focusing”, where the arrows show the direction of flow of the continuous phase, the dispersed phase is shown in blue.

Fig. 3. Microfluidic geometric pattern "Coil", mixing two miscible liquid reagents.

Fig. 4. External view of the central part of the microfluidic chip, showing a “coil” and places for placing tubes for supplying and discharging the working medium.

Carrying out the invention

The operating principle of the invention is as follows: liquid and gaseous reagents are supplied through metering feed systems into series-connected cell modules. The modules implement various functions in accordance with their design and purpose: mixing liquids, mixing liquids with gas, forming monodisperse bubbles of one of the phases, heating the reaction mixture, carrying out a chemical reaction, optical diagnostics of the process, registration of spectra, implemented in several geometries in different wavelength ranges .

A flow modular configurable cell is essentially a compact research chemical reactor and is a system of modules connected in series, equipped with external auxiliary devices.

Each module implements one or more functions and is a planar microfluidic chip enclosed in its own housing, equipped with inputs and outputs of reagents and reaction products in the form of tubes with connecting fittings at the ends.

External auxiliary devices provide supply of liquid and gaseous reagents to the microfluidic system of the cell and their heating, as well as measurement of certain parameters inside the cell: pressure, temperature, pH.

The external devices of the invention include: high-pressure liquid syringe pumps, gas reducers, needle valves, cylindrical heating elements (tubular electric heater), pressure, temperature, pH sensors. Liquid reagents are supplied to the cell system using high-pressure syringe pumps. Syringe pumps supply liquid reagents at a given speed and provide a given pressure in the system. Pressurized gas supply system allows the supply of gases in the pressure range from 1-200 atm., includes a gas reducer, one for each gas, and a needle valve, installed after the reducer in front of the cell module.

Consists of the following parts:

Gas-hydraulic modules

1. liquid input module

2. gas input module

3. liquid mixing module

4. liquid and gas mixing module

5. heating module

6. reaction module.

Spectrum registration modules

1. spectroscopic module with one window, for the implementation of fluorescence techniques

2. spectroscopic module with two windows, for implementing techniques carried out in “transmission” geometry

Depending on the purpose of the flow modular configurable cell - depending on the scientific experimental problem being solved, its configuration and the set of modules included in its system may change.

The modules used as part of the system are divided into two groups: gas-hydraulic and spectroscopic. A module equipped with one window is shown in FIG. 1. Gas-hydraulic modules, unlike spectroscopic ones, do not have windows. Windows are understood as structural elements of modules, which are inserts into the body of the cell module, made of materials that are permeable in a certain range of wavelengths: in the infrared (IR), ultraviolet (UV), visible and X-ray ranges. The following window materials are used: quartz glass, artificial sapphire, glassy carbon. The purpose of the windows is to diagnose the chemical reaction occurring inside the cell using optical methods: XAS, XRD, SAXS.

In fig. Figure 1 shows the cell module of a flow-through modular configurable cell, equipped with a window and designed to record the spectrum during a chemical reaction. The tightness of the module is ensured by a fluoroplastic ring seal and tight crimping carried out by a clamping nut and a clamping coupling, assembled with each other along the thread. On the spectrum recording side, the microfluidic module is covered with a window made of artificial sapphire, which acts as a window transparent to radiation in a certain wavelength range. Depending on the research method, the window can be made of various materials: artificial sapphire, fused quartz, glassy carbon, transparent in the X-ray wavelength range, artificial diamond. The named materials have mechanical strength, heat resistance, chemical inertness, permeability in the appropriate range - the materials are selected in accordance with their throughput in the appropriate ranges. Tubes for supplying the working medium, equipped with connecting fittings, are welded into the cell body. The arrows show the movement of the cell's working environment. Spectrum recording modules are assembled on threads and using polymer seals, gas-hydraulic modules are made of all-metal, their tightness is ensured by argon-arc welding of the housing from the outside, the manufacturing method is described below.

To carry out chemical reactions that occur with the use of a catalyst under conditions of high pressure and high temperatures, and to diagnose the nature of the reactions using optical methods, it is necessary that the design of the research cell meet a number of requirements: strength, optical, chemical, geometric.

Strength requirements are reduced to fulfilling the condition of maintaining tightness under the condition of applied increased internal pressure of up to 200 atm at a temperature of up to 200°C. It should be noted that miniaturization, in addition to the well-known physicochemical advantages associated with better quality of mixing of reagents and a high rate of chemical reaction, makes it possible to impose less stringent requirements on the strength of the cell body structure, since the absolute value of the force acting on a unit of the internal surface of the cell depends on the area to which pressure is applied.

Optical requirements include having windows that are optically transparent in certain wavelength ranges.

Chemical requirements are requirements for the corrosion resistance of research reactor components exposed to a chemically aggressive low pH environment. The presence of requirements for chemical resistance significantly narrows the range of materials that can be used in the cell design. The metal elements of the cell can be made of special corrosion-resistant steels, for example, AISI 316 steel, the Russian equivalent is 07Х18Н13М2. The following materials can be used for windows: artificial sapphire, fused quartz, glassy carbon, artificial diamond. Some plastics can be used as sealing materials, for example, plastics from the polyimide group, polyethylene terephthalate and some others. Thus, only materials that have a combination of chemical resistance to aggressive environments with low pH, thermal resistance and mechanical strength can be used in the cell design.

Geometric requirements include requirements for the shape, size, and aspect ratios of cell elements. The geometric requirements for a flow-through modular configurable cell system can be classified as constructive - to ensure effective control of the mixing of hydrophilic and hydrophobic liquid reagents, as well as the mixing of liquids with gases, and the occurrence of a chemical reaction at a sufficient speed, the internal structure of the reaction volume of the cell must be a system of communicating channels of complex planar geometry. Examples of typical planar geometric shapes characteristic of the functional geometry of channels of microfluidic systems are, for example, the widely used so-called “Flow-focusing” and “T-junction” patterns, as well as the “serpentine” pattern, see Fig. 2, fig. 3.

The Flow-focusing pattern represents the intersection of two mutually perpendicular channels, at the intersection of which two immiscible liquid phases of reagents interact. This microfluidic pattern serves to form monodisperse droplets of one of two immiscible phases. When the flows of two immiscible liquid reagents interact, the dispersed phase coming from the central channel is broken into separate droplets at the intersection with the flow of the continuous phase from two side channels perpendicular to the main channel. As a result of this kind of interaction, a flow of monodisperse droplets of one of the reagents is formed in the flow of the continuous phase of the other. The T-junction pattern serves the same purpose; it is an analogue of the Flow-focusing pattern. The patterns described above can also be used to form a series of individual bubbles in a fluid stream. The coil pattern is used to carry out the process of mixing two mutually miscible liquid reagents.

The channel width typical for microfluidic devices, research microfluidic chips, is 500-50 µm. In this case, the width of the channel can be significantly greater than the height. In other words, the aspect ratio of the height to the width of the reactor channel can be significantly less than unity ≈1/10. The small cross-section of the channel and the corresponding aspect ratio are important for the reaction to proceed at a sufficient speed, and also affects the quality of mixing of the starting reagents. Good indicators of the surface roughness of the channel walls are also important to ensure the appropriate flow of reagents and their mixtures.

It should be noted that many microfluidic chips and devices have been developed in the world, made from a number of materials, of various designs and purposes, used in various fields of physics, chemistry, biology, medicine, etc. Most of the existing developments do not meet the strength, optical, chemical, geometric requirements, compliance with which is necessary for the use of the system as a cell for carrying out homo- and heterogeneous reactions in the liquid phase, with the possibility of introducing gas-phase reagents, including in aggressive environments with low pH, high pressure up to 200 atm and temperatures up to 200 °C, with the possibility of in situ and in operando spectral diagnostics of the nature of the reaction using IR-UV-Vis, XAS, XRD, SAXS methods on synchrotron radiation sources.

Thus, based on the design requirements formulated above, the production task arises of forming indirect planar patterns in materials that simultaneously possess a combination of properties of chemical resistance to aggressive environments, thermal resistance and mechanical strength. And also, in some areas of the reactor, and optical transparency for certain wavelength ranges.

Preparation method

A technical solution and method for producing a flow-through modular configurable cell, compatible with a microfluidic system, for carrying out a chemical synthesis reaction of methane-methanol on gold/platinum/ruthenium nanoparticles and in situ/in operando diagnostics of the process, carried out by X-ray and optical methods IR-UV- Vis, XAS, XRD, SAXS, meeting the requirements stated above and corresponding to the stated purpose.

The proposed technical solution is based on a method for manufacturing the central part of a microfluidic chip using wire-cut electrical discharge machining. This processing method is a method of forming a vertical wall shape - a planar channel shape of indirect geometry with small channel dimensions and corresponding aspect ratio in a metal sheet material. Modern wire-cut electrical discharge machines use wire with a thickness of 30 microns or more for the material processing process, which makes it possible to form slots in sheet metal material with a width of about 40 microns or more. Thus, this processing method makes it possible to form microfluidic channels with a width of 40 μm or more in a sheet metal material, the thickness of which is limited only by the strength of the metal sheet and, in practice, can range from 10 μm or more. Electroerosive machining technology makes it possible to process almost any conductive materials, regardless of their hardness, including metals and alloys, conductive ceramic materials, polycrystalline diamond, and conductive carbon materials.

After the central part of the microfluidic chip in the form of a pattern of vertical walls of a microfluidic channel using wire-cut electrical discharge machining is formed in a thin-sheet metal material (in this case, this is a special corrosion-resistant steel AISI 316-07Х18Н13М2) - a planar shape is cut out, it is necessary to close the channel from the top and bottom . To do this, the central part of the microfluidic chip is placed between two plates - upper and lower, made of the same material. The plates have a thickness that significantly exceeds the thickness of the central part of the microfluidic chip and is typically about 10 mm, with the overall dimensions of the chip being about 30x30 mm. The central part of the microfluidic chip necessarily has a closed internal geometric shape - Fig.4.

One of the plates is solid and has no holes, the other has holes that coincide in location with the location of the corresponding places in the geometry of the microfluidic chip. The plates are welded into the holes, with an outer diameter of 1/8 inch, equipped at the ends with pipe compression fittings, allowing operation at a given pressure and temperature. The tubes serve to supply the working medium through the research cell. Tube fittings are designed for connection to the research cell of pipeline shut-off and control valves, external auxiliary devices, for example, such as a high pressure syringe liquid pump, a pressurized gas supply system including a gas reducer and a needle valve for each gas supply line, and also sensors and measuring systems, such as pressure gauges. Also, pipe compression fittings allow you to connect individual cell modules to each other, thus forming a composite cell formed by the serial connection of individual modules that perform separate functions.

After manufacturing the microfluidic chip, the upper and lower plates, the listed elements are assembled together into a “sandwich”, which is entirely placed in a hydraulic press and compressed at a pressure of about 1 ton with device dimensions of 30x30 mm. In this state, argon-arc welding is performed at the junction of the layers of the device elements: upper plate-chip-bottom plate.

Claims (1)

A flow-through modular cell for carrying out a chemical synthesis reaction, containing a clamping coupling made of cylindrical steel 07Х18Н13М2 with a thread on its outer surface, onto which a clamping nut made of steel 07Х18Н13М2 is screwed; between the clamping coupling and the clamping nut there is a cylindrical body with a protrusion, made of steel 07Х18Н13М2 and on which two through holes are made, into which tubes are rigidly installed, while the body is inserted into a clamping coupling made of a cylindrical shape with a thread on its outer surface; in this case, a window is installed on the body, made in the form of a hollow cylinder, the diameter of which is equal to the outer diameter of the body, made of a material that is transparent in a certain region of the spectrum; There is also a fluoroplastic sealing ring installed between the window and the body, the diameter of which is equal to the outer diameter of the body, and a microfluidic chip is installed on the protrusion of the body coaxially with its holes.