JP7599345B2 - Apparatus and method for searching conditions for forming silica film - Google Patents

Description

The present invention relates to an apparatus and method for exploring conditions for forming silica films.

A method that uses an amorphous silica membrane with selective hydrogen permeability is known as a method for separating hydrogen generated by dehydrogenation of an organic hydride, which is a hydrogen carrier.

Patent Document 1 proposes forming a silica film on a porous substrate and then reacting it with oxygen to stabilize the silica film.

Patent Document 2 proposes supplying the silica film source gas to the substrate while pressurizing it in order to suppress defects in the silica film.

Patent document 3 proposes forming a silica film by a first deposition step in which a silicon compound is deposited on a substrate, and then a second step in which another silicon compound is further deposited.

JP 2009-202096 A JP 2007-216106 A JP 2008-246299 A

A known method for producing silica membranes is to thermally decompose the raw silica source and use a vapor phase method (CVD method) to grow a silica membrane on a porous substrate. It is becoming clear that the performance of the silica membrane depends heavily on the conditions under which the silica membrane is formed by the vapor phase method. In order to form a silica membrane with excellent selective hydrogen permeability, it is necessary to appropriately determine the formation conditions.

However, currently, it is necessary to find the conditions for pyrolysis by trial and error depending on the silica source. In addition, after a silica membrane is prototyped, the permeation and separation performance must be evaluated each time. As a result, it takes a lot of time and effort to determine the conditions for forming a silica membrane.

One aspect of the present invention relates to an apparatus for searching conditions for forming a silica film, the apparatus comprising: a first gas supply unit that generates a first gas containing a silica source; a reactor that is heated while circulating the first gas; a first control unit that controls the amount of the first gas introduced into the reactor; and an analysis device that generates a first profile that shows the relationship between the composition of the product generated by decomposition of the silica source in the reactor and the temperature.

Another aspect of the present invention relates to a method for searching for conditions for forming a silica film using the above-mentioned silica film formation condition searching device, the method including a step of generating a first profile group having a plurality of the first profiles obtained by changing the amount of the first gas introduced into the reactor by the first control unit.

The present invention makes it possible to efficiently explore conditions for forming a silica film.

FIG. 1 is a block diagram showing a configuration of an apparatus for searching conditions for forming a silica film according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing an example of a mixing section included in the silica film formation condition searching device. FIG. 2 is a diagram showing an example of a first profile regarding a low molecular weight product obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing another example of a first profile regarding a low molecular weight product obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing yet another example of a first profile regarding a low molecular weight product obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing yet another example of a first profile regarding a low molecular weight product obtained by the silica film formation condition searching apparatus. FIG. 2 is a diagram showing an example of a first profile relating to low and high molecular weight products obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing another example of a first profile relating to low and high molecular weight products obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing yet another example of a first profile relating to low and high molecular weight products obtained by the silica film formation condition searching apparatus. FIG. 13 is a diagram showing an example in which three candidates for temperature, which is one of the conditions for forming a silica film, are set based on a first profile when DMDMS is used as a silica source. FIG. 13 shows the hydrogen and nitrogen permeance of silica films formed using different temperature conditions.

The following describes an apparatus for searching conditions for forming a silica film according to an embodiment of the present invention (hereinafter also referred to as "search apparatus A"); however, the apparatus according to the present invention is not limited to the following embodiment.

[First gas supply unit]
The searching device A includes a first gas supply unit that generates a first gas containing a silica source. If the silica source is a gas, the first gas supply unit may be a cylinder that can store the silica source and extract it at an arbitrary flow rate. If the silica source is a liquid or solid, the first gas supply unit may have a function of vaporizing the silica source, and may further have a function of controlling the amount of vapor of the silica source generated. The first gas supply unit may have a function of mixing an inert gas with the silica source. That is, the first gas may be substantially composed of only a gaseous silica source (vapor of the silica source) except for components that are inevitably mixed in, or may be a mixed gas containing the silica source and an inert gas. The first gas supply unit may include, for example, a carburetor that injects or sprays an inert gas together with the liquid silica source. Alternatively, the first gas supply unit may include a heater that heats and vaporizes the liquid or solid silica source. The first gas supply unit may have a temperature control unit that controls the output of such a heater.

The silica source is not particularly limited, but may be, for example, a silicon compound that reacts with oxygen to produce silica. Examples of such silicon compounds include tetraalkoxysilanes (tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), etc.), trialkoxysilanes (ethyltrimethoxysilane (Ethyl-TMOS), methyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, etc.), dialkoxysilanes (dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane, etc.), monoalkoxysilanes (trimethylmethoxysilane (TMMOS)), silicon tetrachloride, silanes (SiH ₄ ), disiloxanes (hexamethyldisiloxane (HMDSO), etc.), and cyclic siloxanes (octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, etc.).

[Reactor]
The searching device A includes a reactor in which the temperature is raised while the first gas is circulated. The reactor includes, for example, a passage through which the first gas flows or a chamber in which the first gas resides, and a heater that heats the first gas in the passage or chamber to a temperature at which the silica source decomposes. A part of the product generated by the decomposition of the silica source in the reactor is sent to the analysis device, and the remaining part passes through the passage or chamber and is discharged to the outside of the reactor. The heater may have a function of raising the temperature of the gas in the reactor, for example, from a first temperature of 200°C or less to a second temperature of 600°C or more while controlling the temperature. The first temperature may be, for example, a temperature near room temperature (15°C to 40°C) or a temperature in the range of 40°C to 100°C. The second temperature may be 700°C or more or 800°C or more.

[First control unit]
The searching device A includes a first control unit that controls the amount of the first gas introduced into the reactor. For example, a mass flow controller may be used for the first control unit. The first gas is introduced into the reactor via the first control unit interposed between the first gas supply unit and the reactor. The first control unit may include one mass flow controller, or may include multiple mass flow controllers. For example, the first gas may be introduced into a predetermined space (for example, the "mixing unit" described below) through at least one mass flow controller, and then from that space, it may be introduced into the reactor through at least one mass flow controller.

[Analytical equipment]
The searching device A is equipped with an analysis device that analyzes the composition of products (hereinafter also referred to as "decomposition products") generated by the decomposition of the silica source. The analysis device analyzes the composition of products generated sequentially in a reactor whose temperature is gradually increased from a first temperature to a second temperature. Then, a first profile is generated that shows the relationship between the composition of the products and the temperature. The first profile includes, for example, information on the generation temperatures of various decomposition products. Among these decomposition products, some components contribute to the formation of a good quality silica film, while others degrade the quality of the silica film. The generation temperature and generation amount of each component can be grasped from the first profile.

The analytical device is preferably a device that generates at least a mass spectrum of the product as the first profile. An example of such a device is a quadrupole mass spectrometer (QMS). More specifically, a gas chromatograph mass spectrometer (GC-MS) that combines a QMS with a gas chromatograph (GC) may be used.

The mass spectrum of the product includes at least the spectra of hydrogen, water, carbon monoxide and carbon dioxide. These low molecular weight products (e.g., molecular weight 44 (CO ₂ ) or less) are generated when the silica source decomposes. It is considered that the low molecular weight products are hardly involved in the formation of the silica film. On the other hand, the high molecular weight products that are generated simultaneously with the low molecular weight products may be intermediates (compounds containing silicon (Si) and oxygen, e.g., organic compounds having Si-O bonds) involved in the formation of the silica film or products (e.g., CH ₃ OO-) that are generated in association with the generation of the intermediates. In other words, an increase in the amount of low molecular weight products suggests the generation of intermediates that are important in the formation of the silica film. For example, a temperature near the temperature at which the amount of low molecular weight products generated is maximized is likely to be suitable as a temperature for forming the silica film.

[Second gas supply unit]
The searching device A may further include a second gas supplying section for supplying a second gas that is introduced into the reactor together with the silica source and reacts with the silica source. The second gas may be, for example, an oxidizing gas that oxidizes the silica source. In this case, the second gas flows through a passage or chamber of the reactor together with the first gas and reacts with the silica source in the passage or chamber at a predetermined temperature ranging from the first temperature to the second temperature.

The oxidizer gas may be, for example, oxygen, ozone, dry air, or the like. The oxidizer gas may be, for example, a pure gas consisting essentially of 100% ozone or oxygen, excluding unavoidable components, or may contain components other than oxygen and/or ozone. The concentration of oxygen and/or ozone in the oxidizer gas may be, for example, 20 vol% to 60 vol%. As gases other than oxygen and ozone contained in the oxidizer gas, an inert gas, dry air, or the like may be used.

[Second control unit]
The searching device A having the second gas supply unit may further include a second control unit that controls the amount of the second gas introduced into the reactor. For example, a mass flow controller may be used for the second control unit. The second gas is introduced into the reactor via the second control unit interposed between the second gas supply unit and the reactor. The second control unit may include one mass flow controller, or may include multiple mass flow controllers. In addition, at least a part of the second control unit may be common to the first control unit. For example, the second gas may be introduced into a predetermined space (for example, the "mixing section" described later) through at least one mass flow controller, and then introduced into the reactor from the space through at least one mass flow controller.

[Mixing section]
The searching device A having the second gas supply unit may further include a mixer that mixes the first gas and the second gas before being introduced into the reactor to generate a mixed gas. In this case, the mixed gas of the first gas and the second gas is introduced into the reactor.

Next, we will explain a method for searching conditions for forming a silica film using searching device A (hereinafter, also referred to as "searching method B"). However, the method according to the present invention is not limited to the following embodiment.

<Generation of First Profile Group (1)>
When it is assumed that a silica film is formed on the surface of a porous substrate, a first gas is supplied to a space (hereinafter also referred to as a "first space") communicating with the pores of the porous substrate so that a silica source is retained at a predetermined concentration in the first space. The silica source is heated in the first space or on the surface of the porous substrate, and undergoes a reaction such as decomposition, and is deposited as silica on the surface of the porous substrate to form a silica film.

When the porous substrate has a first surface and a second surface, the first surface and the second surface are connected by pores, the first space is connected to the pores at the first surface, and the second space is connected to the pores at the second surface and is cylindrical, a second gas may be supplied to the second space.

In the above-described silica film formation process, the important conditions are three parameters: the temperature at which the silica source is heated, the flow rate of the silica source (or the first gas) (concentration in the first space), and the flow rate of the oxidizer gas (the second gas) (concentration in the first space or the second space), of which the two most important parameters are the temperature and the flow rate of the silica source. Search method B is useful for searching for the appropriate temperature and flow rate of the first gas for forming a high-quality silica film.

Search method B first has a step of changing the amount of the first gas introduced into the reactor by the first control unit to obtain a plurality of first profiles as a first profile group. Each first profile is a profile that shows the relationship between temperature and the mass spectrum of the decomposition product generated at that temperature when the concentration of the silica source in the reaction chamber, for example, assuming the first space, is kept constant. The first profile includes various information regarding the decomposition behavior of the silica source.

The first profile group having a plurality of first profiles includes, for example, two first profiles measured by changing the flow rate of the first gas so that the concentration of the silica source in the reaction chamber becomes A mol/m ³ and B mol/m ³ (A<B). The concentration of the silica source in the reaction chamber may be further changed to C (≠A, B) mol/m ³ , D (≠A to C), etc. to increase the number of first profiles.

The first profile group enables the output of a mass spectrum with two parameters, temperature and the flow rate of the first gas (e.g., the concentration of the silica source in a reaction chamber assuming the first space), as variables. By using the first profile group, it is possible to easily determine the temperature and flow rate of the silica source at which any decomposition product (e.g., a component that contributes to the formation of a high-quality silica film) is most likely to be produced. When the silica film formation conditions are selected based on the first profile group, the effort and time required to determine the silica film formation conditions can be significantly reduced.

<Generation of the second profile>
A second profile may be generated from the first group of profiles, the second profile indicating the relationship between the amount of the first gas introduced into the reactor, the amount of each component contained in the decomposition product, and the temperature. The second profile is extracted data extracted from the first group of profiles. The second profile may be, for example, a collection of the first profiles at a flow rate of the first gas selected arbitrarily.

<Generation of First Profile Group (2)>
Here, the search method B includes a step of acquiring a plurality of first profiles as a second profile group by changing the amounts of the first gas and the second gas introduced into the reactor by the first control unit and the second control unit. Each of the first profiles is a profile showing the relationship between temperature and the mass spectrum of a decomposition product generated at the temperature when the concentration of the silica source and the concentration of the oxidant gas in a reaction chamber assuming the first space are constant.

The second profile group includes, for example, two first profiles measured by changing the flow rate of the first gas so that the concentration of the silica source in the reaction chamber is A mol/m ³ and B mol/m ³ (A < B) when the concentration of the oxidizer gas in the reaction chamber is constant at amol/m ³ .

The second profile group also includes two first profiles measured by changing the flow rate of the first gas, for example, so that when the concentration of the oxidizer gas in the reaction chamber is constant at b mol/m ³ (a < b), the concentration of the silica source in the reaction chamber is A mol/m ³ and B mol/m ³ (A < B).

That is, the second profile group includes, for example, the above-mentioned four first profiles. The concentration of the oxidant gas in the reaction chamber may be further changed to c (≠ a, b) mol/m ³ , d (≠ a to c), etc. to increase the number of first profiles. In addition, when the oxidant has each of the above concentrations, the concentration of the silica source in the reaction chamber may be further changed to C (≠ A, B) mol/m ³ , D (≠ A to C), etc. to increase the number of first profiles.

The second profile group enables the output of a mass spectrum with three parameters as variables: temperature, the flow rate of the first gas (concentration of the silica source in the reaction chamber assuming the first space), and the flow rate of the second gas (concentration of the oxidizer gas in the reaction chamber assuming the first space). By using the second profile group, it is possible to easily grasp the temperature, flow rate of the silica source, and flow rate of the oxidizer gas at which any decomposition product (e.g., a component that contributes to the formation of a high-quality silica film) is most likely to be produced. When the silica film formation conditions are selected based on the second profile group, the effort and time required to determine the silica film formation conditions can be further significantly reduced.

<Generation of the third profile>
A third profile may be generated from the second group of profiles, the third profile indicating the relationship between the amount of the first gas introduced into the reactor, the amount of the second gas introduced into the reactor, the amount of each component contained in the decomposition product, and temperature. The third profile is extracted data extracted from the second group of profiles. The third profile may be, for example, a collection of the first profiles at flow rates of the first gas and the second gas selected arbitrarily.

Next, a silica film formation condition searching device according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a block diagram showing the configuration of the silica film formation condition searching device. The silica film formation condition searching device 100 includes a first gas supply unit 10 that generates a first gas containing a silica source, a second gas supply unit 20 that supplies a second gas, a reactor 30 that is heated while circulating the first gas and the second gas, a mixing unit 40 that mixes the first gas and the second gas before being introduced into the reactor 30 to generate a mixed gas, and an analysis device 50 that analyzes the composition of the product generated in the reactor 30 to generate a first profile.

Figure 1B is a conceptual diagram showing an example of a mixing section. The mixing section has a narrow tube section through which the first gas and the second gas pass after joining, and the first gas and the second gas are mixed uniformly as they pass through the narrow tube section.

The first gas supply unit 10 includes, for example, a raw material container 11 that contains a liquid silica source, a first heater 12 that heats the raw material container 11, a first temperature control unit 13 that controls the temperature of the first heater 12, and an inert gas supply unit 14 that supplies an inert gas into the raw material container 11. The inert gas functions as a carrier for the vapor of the silica source generated in the raw material container 11. As the inert gas, Ar, N ₂ , He, etc. can be used. The amount of the inert gas sent to the raw material container 11 is controlled by a mass flow controller (not shown).

The second gas supply unit 20 may be, for example, a gas cylinder that supplies an oxidizer gas such as oxygen. The oxidizer gas can be extracted from the gas cylinder at any flow rate.

The reactor 30 includes a chamber 31 into which the mixed gas is introduced, a second heater 32 that heats the gas in the chamber 31, and a second temperature control unit 33 that controls the temperature of the second heater 32. The reactor 30 has an inlet 34 that communicates with the mixing unit 40, and an outlet 35 that sends the gas inside the reactor 30 (including decomposition products, unreacted materials, oxidizing agents, carriers, etc.) to the outside of the reactor 30. The outlet 35 has a branch 36, and a portion of the gas containing the decomposition products is sent to the analysis device 50 through the branch 36.

The amount of the first gas introduced into the mixing section 40 is controlled by a first mass flow controller 60 interposed between the first gas supply section 10 and the mixing section 40. The amount of the second gas introduced into the mixing section 40 is controlled by a second mass flow controller 70 interposed between the second gas supply section 20 and the mixing section 40. The amount of the mixed gas introduced into the reactor 30 is controlled by a third mass flow controller 80 interposed between the mixing section 40 and the reactor 30. As described above, the first mass flow controller 60 and the third mass flow controller 80 both control the amount of the first gas introduced into the reactor 30, and therefore constitute a first control section. The second mass flow controller 70 and the third mass flow controller 80 both control the amount of the second gas introduced into the reactor 30, and therefore constitute a second control section.

A GC-MS or the like can be used as the analytical device 50. The analytical device 50 includes a measurement unit 51 that outputs a mass spectrum, a calculation unit 52 that edits the output of the GC-MS, an output unit 53 that outputs the calculation results as a first profile, and a storage unit 54 that stores the output of the GC-MS, the first profile, etc.

Next, as the first profile, some mass spectra of decomposition products of the silica source are illustrated. FIG. 2 is a diagram showing an example of the first profile obtained by the search device A when nitrogen (N ₂ ) is used as the inert gas in the first gas supply unit 10 and oxygen (O ₂ ) is used as the second gas. Specifically, a first gas having a molar ratio of silica source/N ₂ of 0.1/45 was generated, and the first gas was supplied to the reactor at a flow rate of 400 cm ³ /sec through the mixing unit, and oxygen was supplied to the reactor at a flow rate of 200 cm ³ /sec through the mixing unit, resulting in the mixed gas flowing through the reactor. The internal pressure of the chamber in the reactor was maintained at atmospheric pressure. The temperature of the reactor was raised at 10° C./min to measure the mass spectrum.

The mass spectra (i.e., first profiles) of low molecular weight products obtained when dimethyldimethoxysilane (DMDMS), trimethylmethoxysilane (TMMOS), ethyltrimethoxysilane (Ethyl-TMOS) and hexamethyldisiloxane (HMDSO) are used as silica sources are shown in Figures 2, 3, 4 and 5. Each spectrum gives the relationship between the spectral intensity and temperature of molecular weights 2 (H ₂ ), 15 (-CH ₃ ), 16 (CH ₄ ), 17 (-OH), 18 (H ₂ O), 28 (CO or C ₂ H ₄ ), 32 (O ₂ ) and 44 (CO ₂ ). It is suggested that intermediates useful for forming a good quality silica film are generated in the temperature range where the mass spectrum intensity of the low molecular weight products changes significantly (especially around the temperature corresponding to the peak where the intensity is maximum).

Next, mass spectra (i.e., first profile) of high molecular weight products obtained when dimethyldimethoxysilane (DMDMS), trimethylmethoxysilane (TMMOS) and ethyltrimethoxysilane (Ethyl-TMOS) are used are shown in Figures 6, 7 and 8 along the same temperature axis as that of low molecular weight products. In Figures 6 to 8, it can be seen that in the temperature range where the spectral intensity of the low molecular weight products changes significantly (especially around the temperature corresponding to the peak where the intensity is maximum), a product (CH ₃ OO-) is generated along with an intermediate important for the formation of a good quality silica film. It has been empirically clarified that the product with a molecular weight of 47 represented by CH ₃ OO- suggests the generation of an important intermediate.

9 shows an example in which three candidates for temperature, which is one of the conditions for forming a silica film, are set based on the first profile when DMDMS is used as the silica source. Here, the candidates are temperature A where molecular weight 18 (H ₂ O) shows the second maximum, temperature B immediately after the third maximum, and temperature C which is intermediate between temperatures A and B. Setting such candidates is impossible without the first profile, and even if it is empirically known that the temperature range of 500°C to 700°C is effective, it is necessary to repeat trial and error within the temperature range of 500°C to 700°C.

10 shows the hydrogen and nitrogen permeance of the silica film formed under each temperature condition. Table 1 also shows the ratio of hydrogen permeance to nitrogen permeance ( _H2 / _N2 ) at 550°C, 600°C, and 650°C as an index of hydrogen selective permeability.

To form the silica membrane, a porous support was prepared by coating the surface of a cylindrical body made of α-alumina with an inner diameter of 7 mm, an outer diameter of 10 mm, and a length of 70 mm. The average pore diameter on the outer peripheral surface side of the porous support was 4 nm. A silica membrane was formed on the outer peripheral surface side of the porous substrate by counter diffusion CVD at film formation temperatures of 550°C, 600°C, and 650°C.

From Figure 10 and Table 1, it can be seen that it is desirable to use 650°C as the temperature for forming the silica film.

Silica membranes are effective as hydrogen separation membranes and are industrially useful, for example, as hydrogen gas separation equipment from BFG installed in plants such as steelworks. According to the present invention, it is possible to efficiently search for conditions for forming high-quality silica membranes.

100: Silica film formation condition searching device 10: First gas supply unit 11: Raw material container 12: First heater 13: First temperature control unit 14: Inert gas supply unit 20: Second gas supply unit 30: Reactor 31: Chamber 32: Second heater 33: Second temperature control unit 34: Inlet path 35: Outlet path 36: Branch path 40: Mixing unit 50: Analysis device 51: Measurement unit 52: Calculation unit 53: Output unit 54: Memory unit 60: First mass flow controller 70: Second mass flow controller 80: Third mass flow controller

Claims (11)

a first gas supply unit that generates a first gas containing a silica source;
a reactor in which the temperature is increased while the first gas is being passed through;
A first control unit that controls an amount of the first gas introduced into the reactor;
an analysis device that generates a first profile showing the relationship between a composition of a product produced by decomposition of the silica source in the reactor and a temperature,
The apparatus for searching for conditions for forming a silica film, wherein the analysis device generates at least a mass spectrum of the product as the first profile . a second gas supply unit that supplies a second gas that is introduced into the reactor together with the silica source and reacts with the silica source;
2. The apparatus for searching for conditions for forming a silica film according to claim 1, further comprising: a second control unit that controls an amount of the second gas introduced into the reactor. Further, a mixing unit is provided for mixing the first gas and the second gas before being introduced into the reactor to generate a mixed gas,
The apparatus for searching conditions for forming a silica film according to claim 2 , wherein the mixed gas is introduced into the reactor. The silica film formation condition searching device according to any one of claims 1 to 3, wherein the reactor is heated from a first temperature of 200°C or less to a second temperature of 600°C or more while the first gas is circulating. 2. The apparatus for searching for conditions for forming a silica film according to claim 1 , wherein the mass spectrum of the product includes at least spectra of hydrogen, water, carbon monoxide and carbon dioxide. A method for searching for conditions for forming a silica film using the apparatus for searching conditions for forming a silica film according to claim 1,
A method for searching for conditions for forming a silica film, comprising a step of generating, by the first control unit, a first profile group having a plurality of the first profiles obtained by changing the amount of the first gas introduced into the reactor. The method for searching for conditions for forming a silica film according to claim 6, further comprising a step of generating a second profile from the first group of profiles, the second profile indicating the relationship between the amount of the first gas introduced into the reactor, the amount of each component contained in the product, and temperature. A method for searching for conditions for forming a silica film using the apparatus for searching conditions for forming a silica film according to claim 2, comprising the steps of:
A method for searching for conditions for forming a silica film, comprising a step of generating a second profile group having a plurality of the first profiles by changing the amounts of the first gas and the second gas introduced into the reactor by the first control unit and the second control unit. The method for searching for conditions for forming a silica film according to claim 8, further comprising a step of generating a third profile from the second group of profiles, the third profile showing the relationship between the amount of the first gas and the amount of the second gas introduced into the reactor, the amount of each component contained in the product, and temperature. The method for searching for conditions for forming a silica film according to claim 6 , further comprising the step of selecting the conditions for forming a silica film based on the first group of profiles. The method for searching for conditions for forming a silica film according to claim 8 , further comprising the step of selecting the conditions for forming a silica film based on the second group of profiles.

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