阅读说明：本技术 催化剂用于从甲烷制备甲醇的用途、从甲烷制备甲醇的方法、催化剂及其制备方法 (Use of a catalyst for the preparation of methanol from methane, method for the preparation of methanol from methane, catalyst and method for the preparation thereof ) 是由 J·德德塞克 E·塔博尔 Z·索巴利克 S·斯科莱内克 K·默赖克达 于 2020-04-02 设计创作，主要内容包括：本发明涉及催化剂用于从甲烷制备甲醇的用途,其中所述催化剂包含沸石,其骨架中具有占所述沸石中所有铝原子的总数的至少10％的Al对,并且进一步包含配位在β-阳离子位置的选自Fe、Co、Mn和Ni的过渡金属阳离子,其中所述过渡金属与Al的比率范围为从0.01至0.5；并且条件是所述沸石不是ZSM-5和丝光沸石。本发明进一步涉及制备甲醇的方法、用于通过甲烷直接氧化制备甲醇的催化剂及其制备方法。(The present invention relates to the use of a catalyst for the preparation of methanol from methane, wherein the catalyst comprises a zeolite having in its framework at least 10% of the total number of all aluminium atoms in the zeolite of Al pairs, and further comprises a transition metal cation selected from Fe, Co, Mn and Ni coordinated to the β -cation position, wherein the ratio of the transition metal to Al ranges from 0.01 to 0.5; and with the proviso that the zeolite is not ZSM-5 and mordenite. The invention further relates to a process for the preparation of methanol, a catalyst for the preparation of methanol by direct oxidation of methane and a process for its preparation.)

1. Use of a catalyst for the preparation of methanol from methane, wherein the catalyst comprises a zeolite having at least 10% of Al pairs in the zeolite framework based on the total number of all aluminium atoms in the zeolite, and further comprising a transition metal cation M coordinated to the β -cation position, wherein M is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag,

and wherein the ratio of the transition metal M to Al ranges from 0.01 to 0.5;

and wherein the ratio of Si/Al ranges from 2 to 9;

with the proviso that the zeolite is not ZSM-5 and mordenite.

2. Use according to claim 1, wherein the zeolite is ferrierite, beta zeolite or SSZ-13, according to the Nickel-Strunz classification.

3. Use according to claim 1, wherein M is selected from the group consisting of Fe, Co, Mn and Ni.

4. Process for the preparation of methanol, characterized in that it comprises the following steps:

(i) oxidizing a catalyst for the production of methanol from methane with oxygen at a temperature of up to 300 ℃;

wherein the catalyst comprises a zeolite comprising at least 10% Al pairs in the framework based on the total number of aluminum atoms in the zeolite and comprising a transition metal cation M coordinated at beta-cation positions, wherein M is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag,

and wherein the ratio of the transition metal M to Al ranges from 0.01 to 0.5;

and wherein the ratio of Si to Al ranges from 2 to 9;

with the proviso that the zeolite is not ZSM-5 and mordenite;

(ii) (ii) the oxidised catalyst is contacted with methane at the same temperature as step (i), which interacts with methane to form methanol.

5. A process for the preparation of methanol according to claim 4, wherein the catalyst is activated in an oxygen stream at a temperature of at least 450 ℃ followed by a helium stream prior to step (i).

6. A catalyst for the production of methanol from methane, characterized in that it comprises a zeolite having at least 10% Al pairs in the framework based on the total number of aluminum atoms in the zeolite and comprising a transition metal cation M coordinated at β -cation positions, wherein M is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, wherein the ratio of M to Al ranges from 0.01 to 0.5;

and wherein the ratio of Si to Al ranges from 2 to 9;

with the proviso that the zeolite is not ZSM-5 and mordenite.

7. The catalyst of claim 6, wherein the zeolite is ferrierite, beta zeolite or SSZ-13 according to the Nickel-Strunz classification.

8. The catalyst of claim 6 or 7, wherein the transition metal whose cation is coordinated at the beta-cation site of the zeolite is selected from the group consisting of Fe, Co, Mn and Ni.

9. Process for the preparation of a catalyst according to any one of claims 6 to 8, characterized in that it comprises the following steps:

a) impregnating a dried zeolite with a solution of a transition metal cation M selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, wherein the zeolite has at least 10% Al pairs in the framework based on the total number of aluminum atoms in the zeolite and the ratio of Si to Al ranges from 2 to 9;

b) the impregnation solution is removed and the resulting catalyst is dried.

10. The process according to claim 9, wherein step (b) is followed by step (c) wherein the resulting catalyst is calcined in air and at a temperature of at least 400 ℃, preferably at least 450 ℃.

11. The process according to claim 9 or 10, wherein step (a) is repeated at least once with a fresh impregnation solution of the same transition metal M cation, wherein the transition metal M is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag.

12. The method according to any of the preceding claims 9-11, wherein FeCl is used₃、FeSO₄、Co(NO₃)₂、CoAc₂、Ni(NO₃)₂Or Mn (NO)₃)₂As a transition metal cation solution, or an acetylacetone solution.

Technical Field

The present invention relates to a zeolite based catalyst for the preparation of methanol from methane, a method for its preparation, a method for the preparation of methanol from methane and its use in the preparation of methanol without the need for subsequent extraction of methanol from the zeolite with water or other reagents.

Background

The direct conversion of methane to methanol is a potential method to readily utilize this rich source of energy. The literature describes Cu-zeolites which have the potential to break the C-H bonds in methane and convert them to methanol by hydrolysis. However, the conversion is far from commercial use because the materials used are inefficient and the conversion requires very high activation temperatures (above 400 ℃). In addition, methanol then needs to be extracted from the zeolite by steam. Examples of such zeolites are Cu-MOR, Cu-ZSM-5 or Cu-SSZ-13.

WO 2016/177542 describes a process for the preparation of methanol from methane at temperatures up to 280 ℃ using a zeolite based catalyst, in particular Cu-MOR, Cu-ZSM-5 or zeolite Y or zeolite omega. This patent application proposes a process for converting methane to methanol at temperatures below 280 ℃ and using molecular oxygen as oxidant, characterized in that the main product of the methane oxidation is intimately associated with a catalyst and that the methanol desorption takes place in a separate step in a gas comprising water or other reactive gas (i.e. CO) stream. Cu-MOR was used as catalyst, but zeolite Y or zeolite omega were also mentioned. The advantage of the method is that the whole process can be carried out isothermally at temperatures up to 280 ℃. The reported yield of one operating cycle is very low but can be increased by using a higher operating pressure, thus obtaining about 56.2. mu. mol of methanol per gram of catalyst at 37bar, although the use of a higher pressure is not excluded. The main drawback of this process is that satisfactory yields cannot be obtained without using higher pressures, although the limit for methane conversion is always limited by the potential concentration of active centers, which is directly related to the actual concentration of active metal and also indirectly related to the limit given by the Si/Al value of the zeolite used.

WO 2011/046621 relates to the conversion of methane to methanol using Cu-zeolites. It describes the low temperature oxidation of methane on a specific Cu-zeolite structure, which is structurally characterized in detail as a mono (μ -oxo) di-copper core. This structure then ensures the direct oxidation of methane to methanol. The catalyst used may be regenerated to its original active state after each oxidation cycle. The main disadvantage of this process is that the active structure is sensitive to even traces of moisture, so that not only the activated catalyst but also the entire oxidation process has to be carried out in a completely dry environment.

The yield of one reaction cycle is also low due to the limited concentration of precisely defined active ingredients in the proposed Cu-zeolite. In view of the extremely low water vapour content required, it is expected that achieving this state will impose requirements on the necessary regeneration time of the catalyst, particularly if some water molecules are produced due to selectivity in methane oxidation below 100%.

US 2017/267616 a1 proposes a continuous catalytic process for the oxidation of methane using molecular oxygen and the stable conversion of methane to methanol at relatively low temperatures in a reaction mixture consisting of a mixture of methane, water vapor and oxygen. It suggests metal-zeolites as catalysts, in particular Cu-ZSM-5 and Cu-MOR, although it also allows the use of other zeolites, namely FER and BEA, and does not exclude the use of other cations. Despite this broad definition of a potentially active structure, the structural description of this patent application with respect to the very slow process of forming unique active centers is based on the migration of Cu ions, their reduction to Cu (i) and the formation of Cu-dimers. As an optimal choice for the gradual formation of the active structure, which is therefore only incompletely specified, said patent application points out a fundamental preference of ZSM-5 as an optimal choice for the formation of active centers of this type.

It mentions molecular oxygen as a preferred oxidant, but does not exclude other oxidants, i.e. ozone, NO, N₂O and/or H₂O₂Or a combination thereof.

Among the possible oxygenated substrates, in addition to methane, it is listed other linear and nonlinear hydrocarbons of any structure (linear C1-C12, nonlinear C3-C12), but not specified in the examples.

In addition to water as the protic solvent (if water is absent, methanol is not extracted from the catalyst surface and is thus used in the preparation of methanol), the document discloses that other protic solvents (i.e. ethanol, formic acid or mineral acids, such as HCl and HNO) may provide this reaction step₃) The possible uses of (1).

The main drawbacks of this process are in particular that the conversion of methane is very low, generally not reaching 0.02%, and that trying to increase the conversion only results in a significant decrease in the selectivity of methanol formation (which is not satisfactory even at low conversions and reaches a value of about 70%). The expected yield of methanol per gram of catalyst is therefore small and does not reach technically satisfactory values.

Pappas et al (ChemCatchem 2019,11, 621-627) describe Cu-FER zeolites and their use for the treatment of CH₄Use for conversion to methanol. Zeolites are prepared by ion exchange and their catalytic activity is strongly dependent on the Cu/Al ratio. Although at low Cu levels the catalyst is almost inactive, its activity increases with increasing Cu/Al ratio. This publication reports a Cu/Al ratio range from 0.11 to 0.20. The optimum activation temperature for the zeolite given here is 500 ℃. It mentions the highest yield of Cu/Al 0.20, when the methanol yield is 88. mu. mol/g. Other types of zeolites used are Cu-MOR and Cu-ZSM. A continuing disadvantage of this configuration is low productivity and high catalyst activation temperature.

CN 101875016 a discloses a catalyst for the production of methane by low temperature oxidation. The catalyst consists of a molecular sieve as a support containing an active ingredient comprising copper oxide and a noble metal. Platinum doped Cu-ZSM-5 is mentioned. Methanol was prepared in an autoclave at 150 ℃ and a pressure of 1.5MPa for 3 hours.

Mahuddin, mohammad Haris; SHIOTA, Yoshihito; yoshizawa, Kazunari. methane selective oxidation to methane by metal-exchanged zeolites, a review of active sites and the same reactivity, catalysis Science & Technology,2019,9.8: 1744-; 2044-4753 ISSN; chapters 3-6 describe zeolite catalysts Fe-ZSM-5, Fe-SSZ-13, Cu/Fe-ZSM-5, Cu-MOR, Cu-SSZ-13, Cu-SSZ-16, Cu-SSZ-39, Cu-Omega, Co-ZSM-5, Ni-ZSM-5, which convert methane to methanol. The catalyst is first activated with an oxidizing agent at 250-500 deg.C, then methane is converted to methanol at 25-200 deg.C, and the resulting methanol is then extracted with a suitable solvent or steam.

ZHAO,Guangyu；KENNEDY,Eric；STOCKENHUBER,Michael.Direct oxidation of methane to value-added products using N₂O over Fe-ZSM-5, Fe-Beta and Fe-FER catalysts, Proc.,8th Tokyo Conf.Adv.Catal.Sci.Technol. (TOCAT8).2018 describes the use of N at 350 ℃ C₂The O and Fe-ZSM-5, Fe-beta and Fe-FER catalysts directly oxidize methane.

KRISNANDI, Yuni Krisyuningsih et al, Partial oxidation of methane to methane over methane catalysis Co/ZSM-5.Procedia Chemistry 2015,14: 508-; ISSN 1876-6196 describes the partial conversion of methane to methanol using Co-ZSM-5 as a catalyst. The catalyst was activated at 773K (500 ℃ C.) and the reaction was carried out with steam at 423K (150 ℃ C.). The product was extracted with ethanol.

Various methods for the preparation of methanol from methane are reviewed in Kulkarni, A.R et al, Caption-exchanged zeolites for the selective oxidation of methane to methane, catalysis Science & Technology 2018,8(1),114- & 123. Continuous or periodic processes can be used to produce methanol. In a continuous process, the conversion of the methane/methanol system upon reaction with the oxidation center is limited to a value of about 0.01%, which greatly limits the possible applications of the continuous process.

On the other hand, in a cyclic process, the yield of one oxidation cycle is limited only directly by the concentration of activated centers and the resulting hourly conversion of methane is limited by the length of the complete duty cycle. Since current methanol yield values per cycle are typically up to 160 μmol methanol per gram of catalyst (Grundner, S., M.A.C. Markovits et al (2015) "Single-site coater oxygenates for selective Conversion of methanol to methanol." Nature Communications 6. "" Wulfers, M.J., S.Tekenel et al (2015) "Conversion of methanol to methanol on coater-reactor-pore zeolites." Chemical Communications 51(21):4447 and 4450) and since the overall cycle is typically one hour or more, the average hour methanol yield does not reach a satisfactory value.

Disclosure of Invention

It is an object of the present invention to provide a process for the preparation of methanol from methane which increases the hourly methanol yield (typically expressed as methanol per gram of catalyst per hour) heretofore mentioned in the prior art with a low catalyst activation temperature and without the need for extraction of the methanol with water or other solvents.

This object is achieved by providing a catalyst according to the invention which allows the preparation of methanol from methane by direct oxidation, i.e. without the subsequent extraction of methanol from the catalyst using steam or other reagents (which further prolongs the time required for the whole cycle, or which does not allow the process to be carried out under isothermal conditions). The process thus achieves a significantly higher methanol yield per hour (in grams of catalyst) than the prior art, thanks to an optimal choice of active structure, which ensures a high concentration of specific active centers and achieves the oxidation and production cycles at the same temperature not exceeding 300 ℃. This is achieved by a zeolite based catalyst with a high concentration of locally paired cation structures, where Fe, Co, Mn or Ni cations can be active cations.

The catalyst of the invention therefore comprises a high density of active centers.

The zeolite being based on SiO₄And AlO₄Tetrahedra, which are connected to each other by shared peak oxygens (peak oxygens). The aluminum atoms in a zeolite are present in pairs (so-called "Al pairs" located in one ring of the zeolite) and unpaired (so-called "unpaired Al atoms" and "single Al atoms" located in two different rings of the zeolite). The high concentration of the local paired cation structure of the zeolite means that the zeolite contains a large number of paired aluminium atoms, in particular at least 10% of all the Al atoms in the framework are paired, i.e. always two Al atoms are located in one ring of the zeolite. This arrangement allows a smaller distance between two adjacent transition metal cations comprised in the zeolite structure (high concentration of active centers as the main product of the interaction between the metal cations and the zeolite) and thus a specific catalytic performance of the zeolite of the invention. The actual total Al content in the zeolite, expressed as a percentage by weight, is about 3.5-4%, corresponding to a Si to Al ratio ranging from 2 to 9, preferably from 4 to 9.

In addition, the process for the preparation of methanol from methane according to the present invention has a short overall duration in the whole reaction cycle, since the whole process is isothermal, which results in an increased methanol yield per hour. The catalyst contains a high concentration of active centers as the main product of the interaction between the metal cations and the zeolite, which ensures easy activation of molecular oxygen at low temperatures. After oxidation, an active material is formed having a high concentration of oxidation active sites to facilitate the activation and desorption of methane as methanol.

One object of the present invention is the use of a catalyst for the preparation of methanol from methane, said catalyst comprising a zeolite having in its framework at least 10% of Al pairs based on the total number of all aluminium atoms in the zeolite and comprising a transition metal cation coordinated to the beta-cation position selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, preferably selected from the group consisting of Fe, Co, Mn and Ni, wherein the ratio of said transition metal to Al ranges from 0.01 to 0.5, preferably from 0.25 to 0.4. The paired structure corresponds to two transition metal divalent cations coordinated at two adjacent cation positions, thereby allowing the two cations to function as a binuclear center, the distance corresponding to the two transition metal cations beingPreferably, it isMore preferablyThe distance between two transition metal cations is determined based on the DFT (density functional theory) model, which is based on the X-ray diffraction of zeolites. Each cation is compensated by two aluminum atoms forming a cation site in the ring. Any zeolite allowing the formation of binuclear centers consisting of two cations coordinated to two such cation positions allowing the action of the binuclear centers, such as FER, × BEA, FAU, SSZ-13, MWW, LTA, GME, LEV and OFF type zeolites, and optionally the CHA topology, with Si/Al ratios ranging from 2 to 9, more preferably from 2 to 5, can be used. FER,. BEA, FAU, SSZ-13, MWW, LTA, GME, LEV and OFFThe Si/Al ratio of (A) is preferably in the range of 2 to 9, more preferably 4 to 9. Preferably, the zeolite is Ferrierite (FER), zeolite Beta (BEA) or SSZ-13. Examples of zeolites where such an arrangement is structurally impossible are zeolite ZSM-5(MFI) and Mordenite (MOR). The amount of Al pairs of the zeolite used was determined by a method based on quantitative analysis of the extent of co (ii) complex formation, characterized by a combination of chemical analysis, FTIR and UV Vis spectra. The method is described in publication J.Z.Sobal i k, B.Wichterlov, lubricating and Distribution of Framework aluminum atom in Silicon-Rich Zeolite and Impact on Catalysis, Catalysis Reviews: Science and Engineering 54(2012) 135-.

In a preferred embodiment, the catalyst zeolite comprises at least 20% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite, preferably at least 30% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite, more preferably at least 35% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite, even more preferably at least 40% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite, even more preferably at least 50% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite, and most preferably at least 60% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite.

In a preferred embodiment, wherein the zeolite is a zeolite of type FER, BEA or SSZ-13, preferably of type FER, according to the Nickel-Strunz classification.

The above-described use of the catalyst of the present invention shows 2-2.25 times higher yields (in grams of catalyst) compared to the Cu-FER catalysts of the prior art (Pappas et Al (ChemCatChem 2019,11,621-627, which does not contain at least 10% of Al pairs in the framework based on the total number of all aluminum atoms in the zeolite.) furthermore, due to the more favorable temperature range during the reaction cycle of the present invention, up to four cycles per hour can be performed instead of one cycle, which significantly increases the methanol yield per hour.

Another object of the present invention is a process for the preparation of methanol from methane comprising the steps of:

(i) the catalyst for the preparation of methanol from methane is oxidized with oxygen at a temperature of at most 300 ℃, preferably at most 250 ℃, more preferably 20-200 ℃;

wherein the catalyst comprises a zeolite comprising at least 10% of Al pairs in its framework based on the total number of all aluminum atoms in the zeolite and comprising a transition metal cation coordinated to a beta-cation site selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, wherein the ratio of the transition metal to Al ranges from 0.01 to 0.5, preferably from 0.25 to 0.4. The paired structure corresponds to two divalent cations of a transition metal coordinated at two adjacent cation positions to allow the two cations to function as a binuclear center, the distance corresponding to the two cations of the transition metal beingPreferably, it isEach transition metal cation is compensated by two aluminum atoms forming cation sites in the ring. Any zeolite that allows the formation of binuclear centers consisting of two cations coordinated at two such cation positions that allow the binuclear centers to function may be used, such as zeolites of the following topology types: FER, BEA, FAU, SSZ-13, MWW, LTA, GME, LEV and OFF, or also CHA topology, with Si/Al ratio ranging from 2 to 9, but more preferably with Si/Al ratio values ranging from 2 to 5. The Si/Al ratio of FER,. about.BEA, FAU, SSZ-13, MWW, LTA, GME, LEV and OFF is preferably in the range of 2 to 9, more preferably 4 to 9;

(ii) the oxidised catalyst is contacted with methane at the same temperature as step (i), i.e. at most 300 ℃, preferably at most 250 ℃, more preferably in the range of 20-200 ℃, which interacts with methane to form methanol.

Preferably, said temperature for both steps is 200 ℃.

Preferably, the catalyst is activated prior to step (i) in an oxygen stream (preferably 25ml/min for at least 1 hour) at a temperature of at least 450 ℃ followed by a helium stream (preferably 25ml/min for a further 2 hours).

Another object of the present invention is a catalyst for the production of methanol from methane comprising a zeolite having at least 10% of Al pairs in its framework based on the total number of all aluminum atoms in the zeolite, and a transition metal cation coordinated to the β -cation site selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, wherein the ratio of transition metal to Al ranges from 0.01 to 0.5, preferably from 0.25 to 0.4.

The paired structure corresponds to two divalent transition metal cations coordinated at two adjacent cation positions to allow the two cations to function as a binuclear center, which corresponds to the distance between the two transition metal cations beingPreferably, it isEach transition metal cation is compensated by two aluminum atoms forming cation sites in the ring. Any zeolite that allows the formation of binuclear centers consisting of two cations coordinated at two such cation positions that allow the binuclear centers to function may be used, such as zeolites of the following topology types: FER,. about BEA, FAU, MWW, LTA, GME, LEV and OFF, or also CHA topology, with Si/Al ratio ranging from 2 to 9, but more preferably with Si/Al ratio ranging from 2 to 5. The Si/Al ratio of FER,. about.BEA, FAU, SSZ-13, MWW, LTA, GME, LEV and OFF is preferably in the range of 2 to 9, more preferably 4 to 9;

examples of zeolites where such an arrangement is not possible are ZSM-5 zeolite (MFI) and Mordenite (MOR).

In a preferred embodiment, the zeolite is a zeolite of the FER, BEA or SSZ-13 type, preferably of the FER type, according to the Nickel-Strunz classification.

Another object of the present invention is a process for preparing the catalyst according to the invention, comprising the following steps:

a) immersing the dried zeolite in a solution of transition metal cations, wherein the zeolite is selected from the topological classes FER,. about.bea, FAU, SSZ-13, MWW, LTA, GME, LEV and OFF, or also CHA topological structure, with a Si/Al ratio in the range of 2-9, and the transition metal is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, preferably selected from the group consisting of Fe, Co, Mn and Ni;

b) the impregnation solution is removed and the resulting catalyst is dried.

Preferably, FeCl₃、FeSO₄、Co(NO₃)₂、CoAc₂、Ni(NO₃)₂Or Mn (NO)₃)₂An aqueous solution or an acetylacetone solution of (a) is used as the transition metal cation solution. The impregnation is carried out at room temperature (25 ℃) or at elevated temperature, preferably 60 ℃.

Preferably, step (a) is repeated with fresh impregnation solution, more preferably step (a) is repeated at least twice for 24 hours, more preferably three times for 24 hours.

The drying of the catalyst in step (b) may be carried out in air or in an inert atmosphere (e.g.N)₂) Neutralization is carried out at atmospheric pressure. The average drying time is at least 4 hours. Drying may be carried out at room temperature, or may also be carried out at elevated temperature (e.g., 350 ℃).

Preferably, the zeolite is Ferrierite (FER), BEA or SSZ-13 and the transition metal is Fe, Co, Ni, Mn, Cu. Most preferably, the zeolite is Fe-FER, Co-FER, Ni-FER, Mn-FER, Co-BEA, Fe-SSZ-13.

Optionally, step (b) may be followed by step (c) wherein the resulting catalyst is calcined in air and at a temperature of at least 400 ℃, preferably at least 420 ℃, more preferably 450 ℃.

Examples

Material

Ferrierite, BEA zeolite and SSZ-13 zeolite are used as starting zeolites for the synthesis of the catalyst of the invention.

If ferrierite is used, it is obtained as follows

Commercially available ferrierite is obtained from TOSOH or prepared as follows (designated fer (hi)):

3.0g of sodium aluminate, 80g of water and 0.4g of NaOH are mixed, after 15 minutes, 17g of pyrrolidine are added to the solution obtained and the mixture is stirred for a further 15 minutes. Then 90g of colloidal silica, 30% by weight aqueous suspension (LUDOX-30) were added and the mixture was stirred until homogeneous. The synthetic gel thus prepared was placed in a stainless steel autoclave with a Teflon liner and heated at 145 ℃ for 15 days. The resulting zeolite was washed thoroughly with water and dried. To remove the residual organic template, the resulting ferrierite was calcined in an air stream at 450 ℃ for 5 hours.

Ferrierite (TOSOH) has the following parameters: Si/Al 8.5; 66% of the total amount of Al present is in the form of Al pairs; 45% of the total amount of Al present is in the form of a pair of adjacent Al pairs. A pair of adjacent Al pairs is defined as a pair of Al pairs forming two adjacent cation sites, wherein a pair of cations is spaced apart after being occupied by a pair of cations

Ferrierite (designated fer (hi)) prepared by the above procedure had the following parameters:

Si/Al 9; 56% of the total amount of Al present is in the form of Al pairs; 35% of the total amount of Al present is in the form of a pair of adjacent Al pairs.

If BEA zeolite is used, it is synthesized as follows

10g of NaAlO₂Dissolved in 1000ml of deionized water, followed by addition of 42g of NaOH and stirring for 40 minutes, addition of 96g of micronized silicon dioxide (Cabosil), stirring for 10 minutes and addition of 5g of beta-zeolite nuclei. The resulting mixture was then homogenized for 5 minutes. The synthesis was carried out in a 2500ml unstirred autoclave at 120 ℃ for 125 hours under autogenous pressure. The zeolite product was washed with deionized water and dried at 80 ℃ for 6 hours. Drying the mixtureThe zeolite was calcined at 540 ℃ for 8 hours in an air stream.

BEA zeolite has the following parameters: Si/Al 4.5; 30% of the total amount of Al present is in the form of Al pairs; 30% of the total amount of Al present is in the form of a pair of adjacent Al pairs.

If SSZ-13 zeolite is used, it is synthesized as follows

SSZ-13 Si/Al 4.5

5g of sodium silicate (26.5% by weight of SiO)₂) (SIGMA-Aldrich) was added to 60g of deionized water and stirred for 15 minutes, followed by 1g of zeolite Y (as Na, Si/Al ═ 2.5) and further stirred for 30 minutes. 13.15g of 20% by weight TMADOH (tetramethylammonium hydroxide, China supplier) were added and stirred for a further 30 minutes, and the resulting mixture was then placed in an autoclave at 140 ℃ and rotated for 6 days.

The synthesized SSZ-13 has the following parameters: Si/Al 4.5; 50% of the total amount of Al present is in the form of Al pairs; 40% of the total amount of Al present is in the form of a pair of adjacent Al pairs.

SSZ-13Si/Al 5.5

5g of sodium silicate (26.5% by weight of SiO)₂) (SIGMA-Aldrich) was added to 60g of deionized water and stirred for 15 minutes, followed by addition of 2.1g of Al₂(SO₄)₃Zeolite and further stirred for 30 minutes. 13.15g of 20% by weight TMADOH (China supplier) were added and stirred for a further 30 minutes, after which the synthesis mixture was placed in an autoclave at 140 ℃ and rotated for 6 days.

The synthesized SSZ-13 has the following parameters: Si/Al 5.5: 40% of the total amount of Al present is in the form of Al pairs; 35% of the total amount of Al present is in the form of a pair of adjacent Al pairs.

Characteristics of the catalyst

The amount of Al pairs of the zeolite used was determined by a method based on quantitative analysis of the extent of co (ii) complex formation, characterized by a combination of chemical analysis, FTIR and UV Vis spectroscopy. The method is described in detail in publication J.Z.Sobalík,B.Wichterlov-factor, lubricating and Distribution of Framework aluminum atom in Silicon-Rich Zeolites and Impact on Catalysis, Catalysis Reviews: Science and Engineering 54(2012) 135-.

The optimum local arrangement frequency for each zeolite is deduced from the Si/Al values, Al pair frequencies and known zeolite topologies, which include two pairs of adjacent pairs that always have a total of four aluminum atoms and are necessary to form binuclear metal ion centers.

Example 1: catalytic testing (all samples are identical)

The products of the catalytic reaction were monitored by mass spectrometry. A uniform distribution of catalyst particles in the range of 600-300 μm is achieved by pressing, crushing and sieving the powder. The tests were carried out in a quartz reactor using 0.25 to 0.50g of catalyst sample. The reaction uses a tube furnace with a temperature controlled by a thermocouple. Prior to the first reaction cycle, the catalyst sample was heated in an oxygen stream (25ml/min) at 450 ℃ for 1 hour, and then in a helium stream (25ml/min) at the same temperature for an additional 2 hours. The temperature was then reduced (rate 10 ℃/min) to 200 ℃ in a stream of inert gas.

Subsequently, a catalytic cycle of methane oxidation is carried out. The sample was exposed to a flow of oxygen (25ml/min) for 10 minutes and purged with argon (25ml/min) for 1 minute. And CH₄(25ml/min) of the interaction was continued for 5 minutes, and then the reactor was purged with a stream of inert gas for 1 minute. Signals were detected at m/z 31 for methanol, at m/z 29 for other possible oxidation products (e.g. formaldehyde, formic acid, dimethyl ether) and at m/z 44 for carbon dioxide. The signal m/z was integrated at 31 and compared to calibration data for methanol to quantify methanol yield. The cycle was repeated five times and no decrease in methanol yield was observed.

Example 2: Fe-FER (TOSOH) catalyst (Fe/Al 0.03)

Fe-FER zeolite, Si/Al 8.5, Fe/Al 0.03 by using FeCl₃Is prepared by dipping in acetylacetone (AcAc) solution. For this purpose, NH is added₄A granulated sample of FER (TOSOH) (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. To 1g of dehydrated zeolite was added a solution of 0.10g of FeCl₃And 170g of an immersion solution of AcAc and left overnight at room temperature. The next day, the excess impregnating solution was removed by filtration. The samples thus prepared were heated under dynamic vacuum as follows: heating at 100 deg.C for 1h, and then at 350 deg.C for 3h (heating rate of 4 deg.C/min). After cooling to room temperature, the sample was filtered off and washed with distilled water and then dried at room temperature.

The material thus prepared was calcined in air at 450 ℃ for 24 hours.

In the reaction test according to example 1, 170. mu. mol of methanol per hour per gram of catalyst were obtained, while 20. mu. mol of a mixture of formaldehyde and dimethyl ether, i.e. oxygenates, per hour per gram of catalyst were obtained.

Example 3: Fe-FER (TOSOH) catalyst (Fe/Al 0.25)

Fe-ferrierite, Fe/Al 0.25 by using FeCl₃Is prepared by dipping in acetylacetone (AcAc) solution. For this purpose, NH₄A granulated sample of FER (TOSOH) (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. To 1g of dehydrated zeolite was added a solution of 0.82g of FeCl₃And 14.20g of AcAc, and left overnight at room temperature. The next day, the excess impregnating solution was removed by filtration. The samples thus prepared were heated under dynamic vacuum as follows: heating at 100 deg.C for 1h, and then at 350 deg.C for 3h (heating rate of 4 deg.C/min). After cooling to room temperature, the sample was filtered off and washed with distilled water and then dried at room temperature.

The material thus prepared was calcined in air at 450 ℃ for 24 hours.

In the reaction test according to example 1, 1600. mu. mol of methanol per hour per gram of catalyst were obtained, while 400. mu. mol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst were obtained.

Example 4: Fe-FER (TOSOH) catalyst (Fe/Al 0.30)

Fe-ferrierite, Fe/Al 0.30 by reaction with FeSO₄Ion exchange of water solution. 1g of sample was treated with 100ml of 0.05M FeSO₄The solution was exchanged twice for 12 hours. Before the preparation of the solution, the distillation used was removed by bubbling with a stream of nitrogen for 1 hourOxygen is removed from the water. The ion exchange was carried out in a closed vessel under nitrogen atmosphere. The sample was then centrifuged under nitrogen and dried at room temperature under a stream of nitrogen.

In the reaction test according to example 1, 1800. mu. mol methanol per hour per gram catalyst and 500. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained.

Example 5: Fe-FER (TOSOH) catalyst (Fe/Al 0.45)

Fe-FER zeolite, Si/Al 8.5, Fe/Al 0.45 by using FeCl₃Is prepared by dipping in acetylacetone (AcAc) solution. For this purpose, NH₄A granulated sample of FER (TOSOH) (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. 1.48g FeCl was added to 1g of dehydrated zeolite₃And 25.56g of AcAc, and left overnight at room temperature. The next day, the excess impregnating solution was removed by filtration. The samples thus prepared were heated under dynamic vacuum as follows: heating at 100 deg.C for 1h, and then at 350 deg.C for 3h (heating rate of 4 deg.C/min). After cooling to room temperature, the sample was filtered off and washed with distilled water, then dried at room temperature and calcined in air at 450 ℃ for 24 hours.

In the reaction test according to example 1, 680. mu. mol methanol per hour per gram catalyst and 90. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained as a mixture.

Example 6: Co-FER (TOSOH) catalyst (Co/Al 0.15)

Co-FER zeolite, Si/Al 8.5, Co/Al 0.15 by NH₄FER (TOSOH) powder samples with 0.05M Co (NO)₃)₂ 6H₂O aqueous solution was prepared by ion exchange at 60 deg.C (1X 12h, 50ml solution/1 g zeolite). After ion exchange, the zeolite was washed thoroughly and air dried at room temperature.

In the reaction test according to example 1, a mixture of 150. mu. mol methanol per hour per gram catalyst and 20. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst was obtained.

Example 7: Co-FER (TOSOH) catalyst Co/Al 0.30

Co-FER zeolite, Si/Al 8.5, Co/Al 0.15 was prepared by ion exchange with 0.05M aqueous cobalt acetate at 60 deg.C (3X 24h, 100ml solution/1 g zeolite). The samples were then washed thoroughly and air dried at room temperature.

In the reaction test according to example 1, a mixture of 900. mu. mol methanol per hour per gram catalyst and 60. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst was obtained.

Example 8: Co-FER (TOSOH) catalyst (Co/Al 0.35)

Co-FER zeolite, Si/Al 8.5, Co/Al 0.35 by reaction with CoAc₂Ion exchange preparation. To 100ml of 0.05M CoAc₂1.0g NH was added to the aqueous solution₄FER (TOSOH) and stirring at 70 ℃ for 12 hours. This process was repeated three times. Subsequently, the resulting material was filtered off and washed thoroughly with distilled water, and then dried at room temperature. The dried sample was heated to 450 ℃ in an air stream for 24 hours.

In the reaction test according to example 1, 1900. mu. mol methanol per hour per gram catalyst and 200. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained.

Example 9: Co-FER (TOSOH) catalyst (Co/Al 0.44)

Co-FER zeolite, Si/Al 8.5, Co/Al 0.44 by reaction with 0.05M Co (NO)₃)₂The aqueous solution was prepared by ion exchange at 60 ℃ (3X 12h, 50ml solution/1 g zeolite). After ion exchange, the zeolite was washed thoroughly and air dried at room temperature.

In the reaction test according to example 1, 550. mu. mol methanol per hour per gram catalyst and 50. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained.

Example 10: Ni-FER (TOSOH) catalyst (Ni/Al 0.18)

Ni-FER zeolite, Si/Al 8.5, Ni/Al 0.18 by reaction with 0.05M Ni (NO)₃)₂ 6H₂Aqueous O solution was prepared by ion exchange at 30 ℃ (1X 12h, 50ml solution/1 g zeolite). After ion exchange, the zeolite was washed thoroughly and air dried at room temperature.

In the reaction test according to example 1, 100. mu. mol methanol per hour per gram catalyst and 30. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained.

Example 11: Ni-FER (TOSOH) catalyst (Ni/Al 0.32)

Ni-FER zeolite, Si/Al 8.5, Ni/Al 0.32 by using Ni (NO)₃)₂And (3) soaking in an aqueous solution. Reacting NH₄A granulated sample of FER (TOSOH) (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. 1ml of Ni (NO) with a concentration of 2.0 wt.% was added dropwise to the zeolite₃)₂ 6H₂And (4) O solution. The samples were then air dried at room temperature for 24 hours and then calcined in air at 450 ℃ for 4 hours.

In the reaction test according to example 1, 1700. mu. mol of methanol per hour per gram of catalyst and at the same time 550. mu. mol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst were obtained.

Example 12: Ni-FER (TOSOH) catalyst (Ni/Al 0.45)

Ni-FER zeolite, Si/Al 8.5, Ni/Al 0.45 granulated NH dehydrated at 120 ℃ for 4 hours by immersion in a stream of air (25ml/min)₄FER (TOSOH) (particle size 600-300 μm). To the zeolite 0.28g of Ni (NO) was added dropwise₃)₂ 6H₂A solution of O in 1ml of water. The samples were then air dried at room temperature for 24 hours and then calcined in air at 450 ℃ for 4 hours.

In the reaction test according to example 1, a mixture of 570. mu. mol methanol per hour per gram catalyst and 130. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst was obtained.

Example 13: Mn-FER (TOSOH) catalyst (Mn/Al 0.16)

Mn-FER zeolite, Si/Al 8.5, Mn/Al 0.16 by reaction with 0.05M Mn (NO)₃)₂The aqueous solution was prepared by ion exchange at 60 ℃ (1X 12h, 50ml solution/1 g zeolite). After ion exchange, the zeolite was washed thoroughly and air dried at room temperature.

In the reaction test according to example 1, 80. mu. mol methanol per hour per gram catalyst and 15. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst were obtained.

Example 14: Mn-FER (TOSOH) catalyst (Mn/Al 0.28)

Mn-FER zeolite, Si/Al 8.5, Mn/Al 0.28 by reaction with 0.05M Mn (NO)₃)₂Ion exchange of water solution. To 100ml of 0.05M Mn (NO)₃)₂1.0g NH was added to the aqueous solution₄FER (TOSOH), and stirring at 70 ℃ for 12 hours. This process was repeated three times. After ion exchange, the resulting material was filtered off and washed thoroughly with distilled water, then dried at room temperature.

In the reaction test according to example 1 1500. mu. mol of methanol per hour per gram of catalyst were obtained, while 350. mu. mol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst were obtained.

Example 15: Mn-FER (TOSOH) catalyst (Mn/Al 0.35)

Mn-FER zeolite, Si/Al 8.5, Mn/Al 0.35 by using Mn (NO)₃)₂And (3) soaking in an aqueous solution. NH (NH)₄A granulated sample of FER (TOSOH) (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours.

1ml of a solution containing 2.0 wt.% of Mn (NO) per gram of zeolite was added dropwise to the dried zeolite₃)₂ 4H₂A solution of O. The samples were then air dried at room temperature for 24 hours and then calcined in air at 450 ℃ for 4 hours.

In the reaction test according to example 1, 1800 μmol of methanol per hour per gram of catalyst and simultaneously 600 μmol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst were obtained.

Example 16: Co-BEA catalyst (Co/Al 0.30)

To 100ml of 0.05M Co (NO)₃)₂1.0g of zeolite NH with Si/Al 4.5 was added to the aqueous solution₄Beta and the mixture was stirred at room temperature for 12 hours. The zeolite was then filtered off and washed thoroughly with distilled water and dried at room temperature.

In the reaction test according to example 1, 450. mu. mol of methanol per hour per gram of catalyst was obtained, while 40. mu. mol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst was obtained.

Example 17: Co-BEA catalyst (Co/Al 0.50)

To 100ml of 0.05M CoAc₂1.0g of zeolite NH with Si/Al 4.5 was added to the aqueous solution₄Beta and the mixture was stirred at room temperature for 12 hours. This process was repeated three times. The zeolite was then filtered off and washed thoroughly with distilled water and dried at room temperature.

Subsequently, the material was heated to 450 ℃ in an air stream for 24 hours.

In the reaction test according to example 1, 550. mu. mol of methanol per hour per gram of catalyst was obtained, while 40. mu. mol of a mixture of formaldehyde and dimethyl ether per hour per gram of catalyst was obtained.

Example 18: Fe-SSZ-13 catalyst (Fe/Al 0.1)

The Fe-SSZ-13 zeolite, Si/Al 4.5, Fe/Al 0.1, was prepared by impregnation with acetylacetone. NH (NH)₄The granulated sample of SSZ-13 (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. To 1g of dehydrated zeolite was added a solution of 0.10g of FeCl₃And 1.70g of AcAc, and left overnight at room temperature. The next day, the excess impregnating solution was removed by filtration. The samples thus prepared were heated under dynamic vacuum as follows: heating at 100 deg.C for 1h, and then at 350 deg.C for 3h (heating rate of 4 deg.C/min). After cooling to room temperature, the sample was filtered off and washed with distilled water, then dried at room temperature and calcined in air at 450 ℃ for 24 hours.

In the reaction test according to example 1, 250. mu. mol of methanol per hour per gram of catalyst was obtained, while a mixture of formaldehyde and dimethyl ether of 30. mu. mol per hour per gram of catalyst was obtained.

Example 19: Fe-SSZ-13 catalyst Fe/Al 0.15

SSZ-13 zeolite, Si/Al 5.5Fe/Al 0.15, was prepared by impregnation with acetylacetone.

NH₄The granulated sample of SSZ-13 (particle size 600-300 μm) was dehydrated in an air stream (25ml/min) at 120 ℃ for 4 hours. To 1g of dehydrated zeolite was added a solution of 0.10g of FeCl₃And 1.70g of AcAc, and left overnight at room temperature. The next day, the excess impregnating solution was removed by filtration. Prepared in this wayThe samples were heated under dynamic vacuum as follows: heating at 100 deg.C for 1h, and then at 350 deg.C for 3h (heating rate of 4 deg.C/min). After cooling to room temperature, the sample was filtered off thoroughly and washed with distilled water, then dried at room temperature and calcined in air at 450 ℃ for 24 hours.

In the reaction test according to example 1, 220. mu. mol of methanol per hour per gram of catalyst was obtained, while a mixture of formaldehyde and dimethyl ether of 30. mu. mol per hour per gram of catalyst was obtained.

Example 20: Fe-FER (HI) catalyst (Fe/Al 0.28)

Fe-ferrierite, Si/Al 9, Fe/Al 0.28 by reaction with FeSO₄Ion exchange of water solution.

1g of sample was treated with 100ml of 0.05M FeSO₄The solution exchanges were performed twice for 12 hours. Prior to the preparation of the solution, oxygen was removed from the distilled water used by bubbling with a stream of nitrogen for 1 hour. The ion exchange was carried out in a closed vessel under nitrogen atmosphere. The sample was then centrifuged under nitrogen and dried at room temperature under a stream of nitrogen.

In the reaction test according to example 1, a mixture of 800. mu. mol methanol per hour per gram catalyst and 50. mu. mol formaldehyde and dimethyl ether per hour per gram catalyst was obtained.

Example 21: comparison of the catalyst of the invention with the Cu-FER catalyst of the publication (ChemCatchem 2019,11,621-627, Pappas et al)

The catalysts prepared according to the invention in examples 8 and 11 were compared with the Cu-FER catalyst according to the above publication. The test was carried out according to example 1. The Cu to Al ratio of the prior art Cu-FER catalyst was 0.2, the Si to Al ratio was 10 and the hourly methanol yield per gram of the catalyst was very low. In contrast, the methanol yield per cycle of the catalyst according to the invention is about 10-fold, and with the possibility of reproducing preparation cycles up to 4 times per hour in the case of the present invention, and the very long cycles in this publication (about 18 hours), the process of the invention provides an uneconomically higher average hourly methanol yield.