CN116622076A - Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application - Google Patents
Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application Download PDFInfo
- Publication number
- CN116622076A CN116622076A CN202310408641.XA CN202310408641A CN116622076A CN 116622076 A CN116622076 A CN 116622076A CN 202310408641 A CN202310408641 A CN 202310408641A CN 116622076 A CN116622076 A CN 116622076A
- Authority
- CN
- China
- Prior art keywords
- organic framework
- metal
- organic
- cam
- zinc
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000926 separation method Methods 0.000 title claims abstract description 20
- 238000001179 sorption measurement Methods 0.000 title abstract description 12
- RYPKRALMXUUNKS-UHFFFAOYSA-N 2-Hexene Natural products CCCC=CC RYPKRALMXUUNKS-UHFFFAOYSA-N 0.000 title abstract description 4
- 238000002360 preparation method Methods 0.000 title abstract description 4
- 239000013334 ultra-microporous metal-organic framework Substances 0.000 title description 2
- 239000012621 metal-organic framework Substances 0.000 claims abstract description 34
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000013110 organic ligand Substances 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 14
- LSPHULWDVZXLIL-LDWIPMOCSA-N (?)-Camphoric acid Chemical compound CC1(C)[C@@H](C(O)=O)CC[C@@]1(C)C(O)=O LSPHULWDVZXLIL-LDWIPMOCSA-N 0.000 claims abstract description 9
- KLSJWNVTNUYHDU-UHFFFAOYSA-N Amitrole Chemical compound NC1=NC=NN1 KLSJWNVTNUYHDU-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 5
- 229940057499 anhydrous zinc acetate Drugs 0.000 claims abstract description 3
- DJWUNCQRNNEAKC-UHFFFAOYSA-L zinc acetate Chemical compound [Zn+2].CC([O-])=O.CC([O-])=O DJWUNCQRNNEAKC-UHFFFAOYSA-L 0.000 claims abstract description 3
- 239000013336 microporous metal-organic framework Substances 0.000 claims abstract 2
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 claims description 13
- 239000003446 ligand Substances 0.000 claims description 12
- 239000011701 zinc Substances 0.000 claims description 10
- 239000013078 crystal Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- -1 D-camphoric acid radical ion Chemical class 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 3
- 239000013094 zinc-based metal-organic framework Substances 0.000 claims description 3
- 238000004458 analytical method Methods 0.000 claims description 2
- 239000011259 mixed solution Substances 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 238000004729 solvothermal method Methods 0.000 claims description 2
- 230000002194 synthesizing effect Effects 0.000 claims 1
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 abstract description 8
- 239000001294 propane Substances 0.000 abstract description 4
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 abstract description 4
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 abstract description 4
- 239000002178 crystalline material Substances 0.000 abstract description 3
- 238000012216 screening Methods 0.000 abstract 1
- 239000002904 solvent Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 238000004821 distillation Methods 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 239000012528 membrane Substances 0.000 description 2
- 239000013265 porous functional material Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910017488 Cu K Inorganic materials 0.000 description 1
- 229910017541 Cu-K Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
- 229920001795 coordination polymer Polymers 0.000 description 1
- 238000002447 crystallographic data Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000013384 organic framework Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G83/00—Macromolecular compounds not provided for in groups C08G2/00 - C08G81/00
- C08G83/008—Supramolecular polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/223—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material containing metals, e.g. organo-metallic compounds, coordination complexes
- B01J20/226—Coordination polymers, e.g. metal-organic frameworks [MOF], zeolitic imidazolate frameworks [ZIF]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
Abstract
A preparation method of a super-microporous metal organic framework and application of propylene-propane adsorption separation belong to the technical field of crystalline materials. The metal organic framework is prepared by solvent thermal reaction of an organic ligand D-camphoric acid, 3-amino-1, 2,4 triazole and anhydrous zinc acetate in N, N-dimethylformamide and tetrafluoroboric acid; gas adsorption research shows that the metal organic framework material has the potential of screening two gas molecules of propylene and propane.
Description
Technical Field
The invention belongs to the technical field of crystalline materials, and relates to a metal-organic coordination polymer material, which is characterized by a zinc metal-based organic framework material, a preparation method and propylene-propane adsorption separation application thereof.
Background
The separation of propane/propylene mixtures is an important and challenging task in the petrochemical industry. Molecular separations with similar physical/chemical properties are difficult in industry and generally require the use of high energy consuming cryogenic distillation techniques. The main disadvantage of distillation is that it is based on the principle of volatility only, and the energy utilization efficiency of this technique is low despite its simple flow. The distillation is replaced by a process with relatively low energy consumption, so that the energy can be obviously saved, and the adsorption method and the membrane separation method have great prospects in gas separation, and the key point is the design and construction of porous functional materials. These materials are able to distinguish between these molecules by different mechanisms, depending on their inherent structural characteristics. So that porous materials are researched and developed in the academic world and the industrial world, and the separation of low-carbon hydrocarbon is carried out by adsorption or membrane separation technology, so that the efficiency of the separation process is improved and the energy is saved.
Metal-organic frameworks (MOFs) are novel porous functional materials which are crystalline materials with periodic network structures formed by connecting Metal nodes (Metal ions or clusters) and organic ligands through coordination bonds. The MOFs have potential application values in a plurality of fields such as adsorption separation, gas storage, sensing and catalysis due to the characteristics of high porosity, large specific surface area, adjustable pore size and properties and the like. In the application of gas adsorption separation, low carbon hydrocarbon separation using MOFs has been widely studied. The implementation method of the separation of the low-carbon hydrocarbon mainly comprises two methods: (1) organic ligands that functionalize MOFs through polar functional groups; (2) Metal sites with coordination unsaturation are introduced on the surface of MOFs holes. Although some MOFs have been reported to be useful for the separation of propylene and propane, the construction of these MOFs uses very complex organic ligands that require cumbersome steps to synthesize. The construction of new MOFs by coordination of simple and easily available inexpensive ligands with metal centers and their use in propylene/propane separations is of great academic significance and practical value.
Disclosure of Invention
The invention aims to synthesize a metal-organic framework material by using a simple and easily available organic ligand and use the metal-organic framework material for C 3 H 6 /C 3 H 8 Is separated from the other components.
The invention is based on two simple and readily available organic ligands, (1R, 3S) -1, 2-trimethyl-1, 3-cyclopentanedicarboxylic acid (D-camphoric acid, H) 2 CAM) and 3-amino-1, 2, 4-triazole (HATZ) to synthesize a zinc-based metal organic framework material.
The metal organic framework is crystallized in an orthorhombic system, and the space group is P2 1 2 1 The unit cell parameters are:
chemical formula is Zn 3 C 28 H 45 N 5 O 11 。
The analysis of the monocrystal structure of the metal organic framework shows that the minimum asymmetric unit is formed by two independent zinc ions, namely a D-camphoric acid radical ion CAM 2- Two deprotonated 3-amino-1, 2, 4-triazoles (ATZ) - ) One N, N-Dimethylformamide (DMF) molecule. Each zinc ion was in tetrahedral configuration with three ATZ - And a CAM (CAM) 2- Ligand coordination, each ATZ - The ligand is attached to three zinc ions, each CAM 2- The ligand bridges two zinc ions; zinc ion and ATZ - The alternating connection of ligands forms a two-dimensional layered structure, CAM 2- The ligands prop the two-dimensional layers, forming a three-dimensional framework structure of the MOF.
The structural formulas of the two organic ligands are shown as follows:
the synthesis method of the metal organic framework material comprises the following steps:
under sealed condition, organic ligand D-camphoric acid and 3-amino-1, 2, 4-triazole and anhydrous zinc acetate Zn (CH) 3 COO) 2 In a mixed solution of DMF and tetrafluoroboric acid, the crystals of the metal organic framework are obtained through solvothermal reaction.
Further preferred is the molar ratio of organic ligand to metal salt, i.e., HATZ: D-camphoric acid: zn (CH) 3 COO) 2 2:5:1 per 0.05mmol Zn (CH 3 COO) 2 Corresponding to 2mL of DMF, 0.01-0.03mL of tetrafluoroboric acid and 0.3mL of H 2 O, heat reactionThe reaction temperature is 120-130 deg.c and the reaction time is 48-72 hr.
The invention is used for separating C 3 H 6 /C 3 H 8 A gas mixture. Can be used for complete 100% separation.
Drawings
FIG. 1 is a diagram of the minimum asymmetric unit of the metal organic framework.
Fig. 2 is a schematic three-dimensional structure of the metal-organic framework.
Fig. 3 is an X-ray powder diffraction pattern demonstrating the metal-organic framework.
FIG. 4 shows the metal organic framework material at 298K vs. C 3 H 6 And C 3 H 8 Is drawn from the figure.
Detailed description of the preferred embodiments
The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.
Example 1
The organic ligand (0.024 mmol HATZ and 0.010mmol D-camphoric acid) was reacted with Zn (CH) 3 COO) 2 (0.05 mmol) in 2.0mL of N, N-dimethylformamide, 0.15mL of tetrafluoroboric acid was added and the mixture was sealed in a vial. The crystals of the metal-organic framework were obtained by thermal reaction at 120℃for 72 hours.
Example 2
The organic ligand (0.024 mmol HATZ and 0.010mmol D-camphoric acid) was reacted with Zn (CH) 3 COO) 2 (0.05 mmol) in 2.0mL of N, N-dimethylformamide, 0.13mL of tetrafluoroboric acid was added and the mixture was sealed in a vial. The crystals of the metal-organic framework were obtained by thermal reaction at 130 ℃ for 24 hours.
The test results of the products obtained in the above examples are the same, and are specifically as follows:
(1) Determination of the Crystal Structure:
selecting crystals with regular shapes and smooth surfaces and proper sizes, collecting crystal data on a Rigaku Supernova CCD diffractometer equipped with a graphite monochromatic enhanced Cu-K alpha radiation source at normal temperature, and then analyzing and refining the crystal structure. The structure is shown in fig. 1 to 2. The crystallographic data are shown in table 1.
TABLE 1 crystallographic numbers of metal-organic framework materials
The block diagram of fig. 1 shows that: there are two independent zinc ions in the minimum asymmetric unit, each zinc ion being connected in a different manner.
The block diagram of fig. 2 shows that: in which the metal-organic framework is formed by D-camphoric acid radical ion CAM 2- Is a column, zinc ion and ATZ - The ligand is alternately connected to the obtained layers to form a column layer structure.
FIG. 3 is an X-ray powder diffraction pattern of the MOF.
(2) Gas adsorption test
FIG. 4 is a graph of C at 298K for the material of the present invention 3 H 6 And C 3 H 8 Single component inhalation diagram of (C), wherein C 3 H 6 The adsorption quantity of (C) is greater than C 3 H 8 Is an adsorption quantity of the material with separation C 3 H 6 /C 3 H 8 Is provided).
The foregoing is illustrative of a preferred embodiment of the invention, but the invention should not be limited to that disclosed in this embodiment. So that equivalents and modifications that do not depart from the spirit of the invention are intended to be included within the scope of the invention.
Claims (5)
1. A super-microporous metal-organic framework is characterized by being a zinc-based metal-organic framework material, wherein the zinc-based metal-organic framework material comprises two organic ligands, (1R, 3S) -1, 2-trimethyl-1, 3-cyclopentanedicarboxylic acid (D-camphoric acid, H) 2 CAM) and 3-amino-1, 2, 4-triazole (HATZ);
the metal organic framework is crystallized in an orthorhombic system, and the space group is P2 1 2 1 The unit cell parameters are:
chemical formula is Zn 3 C 28 H 45 N 5 O 11 。
The analysis of the monocrystal structure of the metal organic framework shows that the minimum asymmetric unit is formed by two independent zinc ions, namely a D-camphoric acid radical ion CAM 2- Two deprotonated 3-amino-1, 2, 4-triazoles (ATZ) - ) One N, N-Dimethylformamide (DMF) molecule; each zinc ion was in tetrahedral configuration with three ATZ - And a CAM (CAM) 2- Ligand coordination, each ATZ - The ligand is attached to three zinc ions, each CAM 2- The ligand bridges two zinc ions; zinc ion and ATZ - The alternating connection of ligands forms a two-dimensional layered structure, CAM 2- The ligands prop the two-dimensional layers, forming a three-dimensional framework structure of the MOF.
2. A supermicroporous metal-organic framework according to claim 1, characterized in that the structural formula of the two organic ligands is as follows:
3. a method of synthesizing a supermicroporous metal-organic framework according to claim 1 or 2, comprising the steps of:
under sealed condition, organic ligand D-camphoric acid and 3-amino-1, 2, 4-triazole and anhydrous zinc acetate Zn (CH) 3 COO) 2 In a mixed solution of DMF and tetrafluoroboric acid, the crystals of the metal organic framework are obtained through solvothermal reaction.
4. A process according to claim 3, wherein the molar ratio of organic ligand to metal salt is HATZ/D-camphoric acid/Zn (CH) 3 COO) 2 2:5:1 per 0.05mmol Zn (CH 3 COO) 2 Corresponding to 2mL of DMF, 0.01-0.03mL of tetrafluoroboric acid and 0.3mL of H 2 O, the temperature of the thermal reaction is 120-130 DEG CThe reaction time is 48-72 hours.
5. Use of a supermicroporous metal-organic framework according to claim 1 or 2 for separating C 3 H 6 /C 3 H 8 The gas mixture, achieved a complete 100% separation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310408641.XA CN116622076A (en) | 2023-04-17 | 2023-04-17 | Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310408641.XA CN116622076A (en) | 2023-04-17 | 2023-04-17 | Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116622076A true CN116622076A (en) | 2023-08-22 |
Family
ID=87590965
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310408641.XA Pending CN116622076A (en) | 2023-04-17 | 2023-04-17 | Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116622076A (en) |
-
2023
- 2023-04-17 CN CN202310408641.XA patent/CN116622076A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110016145B (en) | Porous metal-organic framework material, preparation method and adsorption separation application thereof | |
| CN111072987B (en) | Two fluorinated metal organic framework materials, preparation and low-carbon hydrocarbon separation application thereof | |
| CN108559098B (en) | Metal organic framework compound, preparation method and application | |
| CN105001245B (en) | Metal organic framework material of Zn and preparation method and application of metal organic framework material of Zn | |
| CN112592490B (en) | Metal organic framework material of polynuclear cobalt cluster based on two-head pyrazole ligand and application | |
| CN107892750B (en) | Metal organic framework material, preparation method and application | |
| CN113621141B (en) | Metal organic framework compound, preparation method and application thereof in adsorption separation | |
| CN113019330A (en) | Preparation of copper-based metal-organic framework material and acetylene/carbon dioxide separation application thereof | |
| CN108774323B (en) | Zr metal organic framework material based on tetradentate carboxylic acid ligand, preparation method and application thereof | |
| CN113801337B (en) | Metal organic framework material for adsorbing and separating ethylene and ethane and preparation method and application thereof | |
| Chen et al. | Fabrication of MIL-96 nanosheets and relevant c-oriented ultrathin membrane through solvent optimization | |
| CN115678027A (en) | Nickel-based dual-ligand metal organic framework material, preparation method and application | |
| CN110563957B (en) | Preparation method and application of three-dimensional iron-based metal-organic framework | |
| CN108586761B (en) | Three-dimensional metal-organic framework material of zirconium, preparation method and water vapor adsorption application | |
| CN113214493B (en) | Preparation of cobalt-based metal organic framework material and low-carbon hydrocarbon separation application thereof | |
| CN110922606B (en) | Microporous Cu-MOF metal organic framework material constructed by adenine and auxiliary ligand, preparation and application | |
| CN114031783A (en) | Metal organic framework material and preparation method and application thereof | |
| Mendes et al. | Dynamic breathing effect in metal-organic frameworks: Reversible 2D-3D-2D-3D single-crystal to single-crystal transformation | |
| Iwamoto et al. | The metal ammine cyanide aromatic clathrates. XIII. The crystal structure of the Hofmann-type biphenyl clathrate, diamminenickel (II) tetracyanonickelate (II) di-biphenyl: Ni (NH3) 2Ni (CN) 4.2 C12H10 | |
| CN110982084B (en) | Zirconium metal organic framework material based on shortest porphyrin carboxylic acid ligand, preparation and application thereof | |
| CN109851559B (en) | Nickel metal organic framework material based on double-end pyrazole ligand, and preparation method and application thereof | |
| CN116622076A (en) | Preparation method of ultra-microporous metal organic framework and propylene-propane adsorption separation application | |
| CN111286035B (en) | Zn (II) complex based on 4, 4' -dicarboxylic acid dimethyl azobenzene and adenine and synthetic method and application thereof | |
| CN113929922B (en) | Application of anionic Zn (II) -MOF in one-step purification of ethylene | |
| CN110527106B (en) | Multi-core multivariable metal organic framework material and synthesis and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |