Catalyst and its use in fatty acid isomerization

文档序号：751579 发布日期：2021-04-02 浏览：109次中文

阅读说明：本技术 催化剂及其在脂肪酸异构化中的用途 (Catalyst and its use in fatty acid isomerization ) 是由 B·韦尔斯 S·C·C·维德曼 T·范博尔根-布伦克曼 R·B·范特里特于 2019-09-23 设计创作，主要内容包括：本发明涉及一种异构化催化剂,特别是沸石催化剂。本发明提供一种通过改性催化沸石材料来制备特别优选的沸石催化剂的方法。本发明还提供使用这种异构化催化剂使脂肪酸或其烷基酯异构化以生产支链脂肪酸的方法、包含所述支链脂肪酸的组合物以及所述异构化催化剂的用途。(The present invention relates to an isomerization catalyst, in particular a zeolite catalyst. The present invention provides a method for preparing particularly preferred zeolite catalysts by modifying catalytic zeolite materials. The invention also provides a process for the isomerization of fatty acids or alkyl esters thereof to produce branched fatty acids using such an isomerization catalyst, compositions comprising said branched fatty acids and uses of said isomerization catalyst.)

1. An isomerization catalyst comprising micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

2. A catalyst, wherein the catalyst has an activity factor of at least 30000, wherein the activity factor is calculated as shown in formula (I):

active factor ═ S_{Outer cover}X strong NH₃Absorption (I)

Wherein "S_{Outer cover}"is the external surface area of the zeolite in m²Per g, determined by nitrogen physisorption, and "strong NH₃Absorption "refers to the desorption of NH from the catalyst at a temperature of 327-550 ℃ during temperature programmed desorption of ammonia₃Amounts, in. mu. mol/g.

3. A catalyst as claimed in claim 1 or 2, wherein the catalyst is a zeolite or zeolithic material.

4. The catalyst of claim 3, wherein the catalyst is a zeolite of the MFI-type framework.

5. The catalyst of claim 3 or 4, wherein the catalyst is a zeolite and comprises channels having a 10-membered ring structure.

6. The catalyst of any one of claims 3-5, wherein the catalyst is a ZSM-5 zeolite.

7. The catalyst of any one of the preceding claims, wherein the catalyst has at least 80m²S in g_{Outer cover}。

8. The catalyst of any one of the preceding claims, wherein the catalyst has a strong NH of at least 100 μmol/g₃And (4) absorbing.

9. The catalyst of any one of the preceding claims, having a silica to alumina molar ratio (SAR) of at least 15.

10. A zeolite suitable for use in an isomerization catalyst according to any one of the preceding claims wherein the zeolite is obtainable, preferably obtained, by a process for modifying the zeolite structure, the process comprising the steps of:

i) contacting the zeolite with an alkaline solution preferably comprising NaOH;

ii) contacting the zeolite with an acidic solution preferably comprising HCl; and

iii) contacting the zeolite with an ion exchange material.

11. The zeolite of claim 9, wherein the ion exchange material is comprised of NH₄NO₃The ion exchange solution of (1).

12. The zeolite of claim 10, wherein the concentration of the basic solution and/or acidic solution and/or ion exchange solution is less than 1M.

13. The zeolite of any of claims 9-11, wherein the process further comprises the steps of:

iv) calcining the zeolite at a temperature of at least 400 ℃ for at least 2 hours.

14. A method for producing branched chain fatty acids comprising the steps of:

i) contacting a starting material comprising unsaturated fatty acids with a catalyst; and

ii) isomerizing an amount of unsaturated fatty acids using a catalyst to form a composition comprising branched fatty acids;

wherein the catalyst comprises micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

15. The process of claim 14 wherein the zeolite is used at a concentration of 0.1 to 2.8 wt%, based on the total weight of fatty acids in the starting material.

16. The process of claim 14 or 15, wherein the catalyst is an isomerization catalyst of any one of claims 1-9.

17. The process of any of claims 14-16, wherein the composition comprising branched fatty acids comprises at least 20 wt.% branched fatty acids after 6.25 hours of isomerization under step ii).

18. A composition comprising branched fatty acids obtainable, preferably obtained, by the process of any one of claims 14 to 17.

19. A composition comprising a branched fatty acid and a catalyst according to any one of claims 1 to 9.

20. Use of a catalyst for the production of branched fatty acids from a feedstock comprising unsaturated fatty acids, said catalyst comprising micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

21. Use according to claim 16 wherein the catalyst is a zeolite according to any one of claims 3 to 9.

Technical Field

The present invention relates to catalysts suitable for use as isomerization catalysts, in particular zeolite catalysts, a process for the preparation of said zeolite catalysts, a process for the isomerization of fatty acids or alkyl esters thereof to produce branched fatty acids using said catalysts, compositions comprising said branched fatty acids and the use of said catalysts.

Background

Fatty acids are versatile raw materials used in many fields of the chemical industry, including lubricants, polymers, solvents, cosmetics and nutraceuticals. Fatty acids are generally obtained by hydrolysis of triglycerides of vegetable or animal origin. Naturally occurring triglycerides are esters of glycerol and straight chain, even-numbered carboxylic acids, typically 10 to 24 carbon atoms. Most common are fatty acids containing 12, 14, 16 or 18 carbon atoms. These fatty acids may be saturated or unsaturated, i.e. contain one or more unsaturated carbon double bonds.

Straight chain saturated fatty acids with 10 or more carbon atoms are solid at room temperature, which makes them difficult to handle in many applications. Unsaturated long chain fatty acids such as oleic acid are liquid at room temperature and therefore easy to handle, but are unstable due to the presence of one or more carbon double bonds. Branched saturated fatty acids can mimic the properties of straight chain unsaturated fatty acids in many ways. In addition, they are generally more oxidatively stable than unsaturated fatty acids. Thus, for many applications, branched fatty acids are more desirable than straight chain fatty acids. Branched fatty acids have one or more alkyl side chains, which are generally short such as methyl, ethyl or propyl, and may be attached to the carbon chain backbone at any position.

Commercially available branched chain fatty acids such as isostearic acid are obtained as a by-product of the catalytic or thermal dimerization of unsaturated straight chain fatty acids. Isostearic acid is typically produced by heating oleic acid in the presence of a suitable catalyst (typically a smectite clay) to produce dimers, trimers and higher oligomeric acids. However, some of the oleic acid does not polymerize, but rearranges to form branched mono-fatty acids, which can be separated by distillation and hydrogenated. Such saturated branched mono-fatty acids are mixtures of various straight and predominantly branched (including mono-and multi-branched) saturated acids, known as isostearic acid.

Isostearic acid has better oxidative stability than oleic acid and is a very useful product sold in a variety of application areas such as greases and cosmetics. Isostearic acid is also used to make isostearyl alcohol.

EP0683150 from Kao Corporation discloses a process for producing branched chain fatty acids using a zeolite catalyst having a linear microporous structure and an average pore diameter of less than 1 nm. Because they have only a microporous crystalline structure, these catalysts are highly diffusion limited and therefore high catalyst loadings (e.g. 4-8 wt% of the weight of the fatty acid starting material in the examples) are required in order to achieve adequate conversion.

EP1490171 to Akzo Nobel discloses a fatty acid isomerization process using an acidic mesoporous aluminosilicate material (referred to as MAS-5). As shown in Table 1 of said publication, MAS-5 is at 3.7nmThe pore size distribution of the protrusions shows that the protrusions are mesoporous. The pure mesoporous nature of the material results in poor catalytic performance as evidenced by the very high catalyst loading (10 wt% as in example 1) that is required to obtain adequate conversion.

WO2011/136903 discloses a process for the production of branched fatty acids by the combined use of a ferrierite catalyst and a sterically hindered lewis base. The catalyst in this example has only a microporous crystal structure and therefore diffusion is limited and high catalyst loadings are required to achieve adequate conversion. In addition, the ferrierite structure of the catalyst results in significantly more linear products (i.e. the resulting mixed product contains a higher content of linear groups than branched groups). This results in a different nature of the resulting isomerized fatty acids compared to alternative process routes, meaning that the products of the process are not suitable for many of the existing application areas of isostearic acid.

Accordingly, there remains a need for improved processes for the production of branched chain fatty acids by isomerization, and for improved isomerization catalysts for use in such processes.

Disclosure of Invention

The present invention is based, in part, on the inventors' recognition that the process of isomerizing fatty acids or alkyl esters thereof to produce branched fatty acids can be improved by using an improved catalyst, wherein the improved catalyst comprises micropores and mesopores, and wherein the micropore volume (V) is_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component. The catalyst is preferably a zeolite or zeolite-type catalyst. The catalyst must be active for the isomerization of fatty acids or fatty acid alkyl esters and may be conveniently referred to as an isomerization catalyst.

The use of such catalysts may improve the production of branched fatty acids.

Accordingly, the present invention provides a catalyst, wherein the catalyst comprises micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

Additionally or alternatively, the present invention provides a catalyst, wherein the catalyst has an activity factor of at least 30,000, wherein the activity factor is calculated as shown in formula (I):

active factor ═ S_{Outer cover}X strong NH₃Absorption (I)

Wherein "S_{Outer cover}"is the external surface area of the catalyst, in m²(ii) per gram, as determined by nitrogen physisorption; and "strong NH₃Absorption "refers to NH desorbed from the catalyst at a temperature of 327-550 ℃ during temperature programmed ammonia desorption as measured by the test methods herein₃Amounts, in. mu. mol/g.

The present invention provides a process for preparing a suitable zeolite catalyst by modifying the zeolite structure, comprising the steps of:

i) contacting the zeolite with an alkaline solution preferably comprising NaOH;

ii) contacting the zeolite with an acidic solution preferably comprising HCl; and

iii) reacting the zeolite with an ion exchange material, preferably an exchange solution and preferably comprising NH₄NO₃Exchange solution contact of。

The present invention also provides a process for producing branched fatty acids from a starting material (or feedstock) comprising unsaturated fatty acids, wherein the process comprises the steps of:

i) contacting a starting material comprising unsaturated fatty acids with a catalyst; and

ii) isomerizing an amount of unsaturated fatty acids using a catalyst to form a composition comprising branched fatty acids;

The present invention also provides compositions comprising branched chain fatty acids obtainable, preferably obtained, by the methods described herein. The present invention suitably provides a composition comprising branched chain fatty acids.

The present invention provides the use of a catalyst for the production of branched fatty acids from a feedstock comprising unsaturated fatty acids, said catalyst comprising micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

Any aspect of the invention may include any feature described herein, whether or not that feature is described in relation to that aspect of the invention (e.g., that feature may be mentioned in other aspects, contexts or embodiments of the invention).

Detailed Description

It is to be understood that any maximum or minimum amount or range boundary used herein can be independently combined.

It is understood that when the number of carbon atoms in a substituent is described (e.g., "C1-C6"), this number refers to the total number of carbon atoms present in the substituent, including all carbon atoms present in all branches. In addition, when the number of carbon atoms is described as in fatty acids, it refers to the total number of carbon atoms, including the carbon atoms in the carboxylic acid and all the carbon atoms present in all the branches.

Any fatty acid mentioned herein also includes its alkyl esters. Thus, the unsaturated fatty acid alkyl esters described herein may also be used in the starting materials. The alkyl moiety is typically 1 to 3, preferably 1, carbon atoms, although it may be up to half the total carbon number. Specific examples of the alkyl ester include methyl, ethyl and propyl esters of unsaturated fatty acids, preferably methyl ester.

Many of the chemicals useful in the present invention are obtained from natural sources. Due to their natural origin, these chemicals often include a mixture of chemicals. Due to the presence of these mixtures, the various parameters defined herein may be average values and may be non-integer.

It is to be understood that, unless otherwise indicated, reference herein to physical properties of the zeolite also includes physical properties of suitable zeolite-based materials.

Zeolites were described and classified into 3 groups-micropores, mesopores and macropores using the IUPAC pore classification (IUPAC. complex of Chemical Terminology, 2 nd edition, authored by a.d. mcnaught and a.wilkinson, Blackwell Scientific Publications, Oxford 1997). Assuming it is cylindrical, the zeolite pores are grouped by their diameter, as shown in table 1:

TABLE 1

	Micro-pores	Mesopores	Macropore
				Pore size (nm)	Less than 2	2-50	Greater than 50

The micropores, mesopores and macropores mentioned herein are classified according to the IUPAC pore size definition shown in table 1.

Catalyst and process for preparing same

The catalyst of the present invention has a structure comprising micropores and mesopores. More specifically, the present invention provides a catalyst, wherein the catalyst comprises micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component. Advantageously, the catalyst has pores (e.g., micropores) sufficiently small to prevent dimerization of unsaturated fatty acids and coke formation within or in the pore structure of the catalyst and pores (e.g., mesopores and/or macropores) sufficiently large to allow the branched fatty acids or esters thereof to diffuse out of the catalyst rapidly. Thus, the catalyst is optimized to provide the desired shape selectivity and the desired product yield when used.

The catalyst may be an aluminosilicate, preferably a crystalline aluminosilicate. The catalyst preferably has the general formula Mⁿ ⁺ _x/n[AlO₂)_x(SiO₂)_y(y>x)].zH₂O, where M is a metal cation of group IA (i.e., alkali metals, also including hydrogen) or group IIA (i.e., alkaline earth metals), and n is the valence of the metal. The zeolite preferably comprises SiO linked together by shared oxygen atoms₄And AlO₄A tetrahedral microporous network. The aluminum preferably has a structure that results in AlO₄An excess of negative 3+ valences on the tetrahedra, which may be substituted by H⁺Or other cations (e.g. Na)⁺、NH₄ ⁺、Ca²⁺) And (6) compensation. When M is hydrogen, the material is Bronsted acidic, whereas when M is, for example, cesium, the material is basic. Upon heating, the Bronsted acidic hydroxyl groups can condense to produce a co-coordinated unsaturated aluminum, which acts as a Lewis acid site. The concentration of framework aluminum may affect acid strength, density and distribution of acid sites, and Bronsted acidity of Lewis acids.

Silica (SiO) of catalyst₂) With alumina (Al)₂O₃) Can be obtained by having a molar ratio (SAR) ofControlled calcination under steam or steam-free conditions and optionally followed by any extraction that results in the removal of aluminum from the catalyst framework. SAR can be changed by chemical treatment with, for example, ammonium hexafluorosilicate. Alternatively, the SAR can be controlled within limits during the preparation phase by varying the stoichiometric ratio of the reactants. The catalyst used in the present invention may have a SAR of at least 3, preferably at least 5, more preferably at least 10, in particular at least 15, ideally at least 20. The zeolite may have a SAR of at most 200, preferably at most 180, more preferably at most 140, especially at most 100, ideally at most 90. The zeolite may have a SAR in the range of 3 to 200, more preferably 10 to 140 and especially 15 to 100. SAR can be determined by atomic absorption spectroscopy.

The catalyst most suitably may be an aluminosilicate material selected from zeolites or zeolite-like materials. Thus, the catalyst may preferably comprise a zeolitic material. Zeolitic materials can provide the same physical properties as zeolites such as crystallinity, pore structure and acidity, but they can incorporate other atoms in their crystal structure, usually with the effect of altering acidity, but while retaining a similar pore distribution; this may be desirable in some catalytic reactions, for example when high acidity may reduce the yield of the desired product. Examples of zeolitic materials are silicoaluminophosphate materials, commonly referred to as SAPO materials, which incorporate phosphate sites and silica and alumina tetrahedra into their structure. It is to be understood that any zeolite-based material having acidity, diffusivity, and pore size characteristics similar to the zeolites described herein may be employed. Additionally, mixtures of zeolitic materials and zeolitic materials may provide preferred catalysts in which pore size, structure and acidity may be balanced between the two materials to provide optimized selectivity and product yield. Alternatively, the catalyst may be free of zeolitic materials.

The catalyst may be a graded zeolite or zeolite-like material. The hierarchical zeolites or zeolitic-type materials are characterized by micropores combined with one or more types of larger pores (mesopores and/or macropores). The reaction catalyzed by the zeolite or zeolite-like material may occur within the micropores. Since the micropores are connected to the outer surface of the zeolite or zeolite-like material through larger mesopores and/or macropores, the overall reaction rate can be increased by increasing diffusion. The mesopores and/or macropores can be within the crystal and/or between the crystals.

The catalyst is preferably a zeolite.

Zeolites can be classified by the number of atoms in the ring (commonly referred to as T atoms) that form the channels or pores. The zeolite preferably comprises a zeolite having 10-membered rings (i.e., T)₁₀A ring) or a hole. This zeolite belongs to the group of medium pore zeolites and it is therefore preferred that the zeolite is a medium pore zeolite. Examples of medium pore zeolites include zeolites of the MFI, TON and FER framework types. The zeolite is preferably selected from ZSM-5, ZSM-22 and ferrierite, more preferably from ZSM-5 and ZSM-22. The zeolite may suitably comprise pentasil units, and the zeolite is preferably a pentasil zeolite. Most preferably, the zeolite comprises a ZSM-5 structure. The zeolite may be a ZSM-5 zeolite (i.e., the isomerization catalyst may consist of a ZSM-5 zeolite). The zeolite may not comprise a beta zeolite structure (BEA framework type zeolite). The zeolite may not comprise a ferrierite structure (FER framework type zeolite). The zeolite may be free of compounds having 12-membered rings (i.e., T)₁₂A ring) channel or hole; such materials do not provide optimal product shape selectivity.

As can be seen from the above comments, the zeolite catalyst is more preferably an MFI-type zeolite, and the zeolite most preferably comprises a ZSM-5 zeolite. Suitable ZSM-5 zeolites may be prepared as disclosed in US3702886, the contents of which are incorporated herein by reference, and more preferably the ZSM-5 zeolite is modified as provided below.

While it is preferred from the standpoint of catalyst activity that the cation in the zeolite be a proton, it is also possible to use potassium, ammonium or similar types of zeolites after partial or complete conversion to the proton type by suitable means such as ion exchange and/or calcination.

The amount of acidic sites in the catalyst (e.g., in grams) may have a significant effect on the ability of a given weight of catalyst to catalyze the production of branched chain fatty acids. The amount of acid sites can be measured by ammonia Temperature Programmed Desorption (TPD). Ammonia TPD involves first adsorbing ammonia onto a catalyst sample and then controllably heating the sample while monitoring the evolution of ammonia from the sample back into the gas phase, preferably using an automated chemisorption analyzer. The chemisorption analyzer may be a Micromeritics TPD/TPR2900 instrument.

The ammonia TPD process used in the present invention involves adsorbing ammonia onto the surface of a catalyst sample, then heating the sample from room temperature at about 20 ℃ (293K) to 550 ℃ (823K), and measuring the ammonia slip from the sample. The total amount of ammonia desorbed from the sample at 20-550 ℃ is called' Total NH₃The absorption, which is an indication of the total amount of acid sites in the catalyst, is measured in μmol/g. The catalyst may have a total NH content of at least 100. mu. mol/g, preferably at least 150. mu. mol/g, more preferably at least 200. mu. mol/g, ideally at least 250. mu. mol/g, especially at least 300. mu. mol/g₃The amount of absorption. The catalyst may have a total NH content of at most 1000. mu. mol/g, preferably at most 900. mu. mol/g, more preferably at most 800. mu. mol/g, ideally at most 700. mu. mol/g₃The amount of absorption. The ammonia TPD process is preferably as described herein in the test methods.

In accordance with the present invention, it is preferred to form or maintain acidic sites in the catalyst to enhance the catalyst's ability to isomerize unsaturated fatty acids to branched fatty acids; it is believed that the presence of acidic sites is desirable to allow the catalyst to be suitable for use as an isomerization catalyst. The present invention recognizes that such acidic sites have a strong affinity for ammonia, indicating that they are "strong" acidic sites. The amount of strongly acidic sites can be measured by the amount of ammonia desorption above a certain minimum temperature, in this case chosen to be 327 c (600K). The higher this minimum temperature for desorption indicates that ammonia is more strongly adsorbed by the acidic sites. Therefore, the amount of ammonia desorbed from the sample between 327 ℃ and 550 ℃ is referred to as "strong NH3 absorption" as an indicator of the amount of strong acid sites in the catalyst. Both zeolite and zeolite-based catalysts are known to contain or not contain weak and strong acidic sites, and when contained, materials with strong acidic sites are preferred. When present, preferred zeolite catalysts may have a strong NH of at least 50. mu. mol/g, preferably at least 100. mu. mol/g, more preferably at least 150. mu. mol/g, ideally at least 200. mu. mol/g, especially at least 250. mu. mol/g₃And (4) absorbing. In addition, preferred zeolite catalysts may have a strong NH of at most 900. mu. mol/g, preferably at most 800. mu. mol/g, more preferably at most 700. mu. mol/g, ideally at most 600. mu. mol/g₃And (4) absorbing. Materials that are too acidic in use may result inThe yield of the desired product is low.

In addition to the acidity characteristics, a number of physical (tissue or structure) characteristics such as surface area and pore volume can affect the catalytic activity of the isomerization catalyst. The surface area and/or pore volume of the catalyst can be measured by nitrogen physisorption. The surface area and/or pore volume may be calculated based on the BET (Brunauer-Emmett-Teller) theory. The surface area may be based on the total surface area (S) of the zeolite_{General assembly}) It is calculated and then can be divided into micropore surface areas (S) using empirical t-plot_Micro-pores) Mesopore surface area (S)_Mesopores) And large pore surface area (S)_Macropore). Alternatively, the mesopore surface area and the macropore surface area can be combined into the external surface area (S)_{Outer cover}) Thereby S_{General assembly}＝S_Micro-pores+S_{Outer cover}. The specific surface area is preferably measured according to ISO 9277.

Surface area of catalyst (S)_{General assembly}) May be at least 300m²A/g, preferably at least 400m²A/g, more preferably at least 450m²A/g, desirably at least 500m²(ii) in terms of/g. Surface area of catalyst (S)_{General assembly}) May be at most 800m²In g, preferably up to 700m²G, more preferably at most 650m²G, ideally at most 600m²(ii) in terms of/g. This surface area can be measured by nitrogen physisorption, preferably using BET theory, more preferably using the empirical t-plot method.

External surface area (S) of catalyst_{Outer cover}) May be at least 80m²A/g, preferably at least 120m²A/g, more preferably at least 140m²A/g, desirably at least 160m²(ii) in terms of/g. External surface area (S) of zeolite_{Outer cover}) May be at most 600m²A/g, preferably of at most 500m²G, more preferably up to 400m²(ii) in terms of/g. This external surface area can be measured by nitrogen physisorption, preferably using BET theory, more preferably using the empirical t-plot method.

The micropore volume (V) can also be measured using nitrogen physisorption and empirical t-mapping_Micro-pores) Mesopore volume (V)_Mesopores) And total pore volume (V)_Hole(s)) And thus V_Hole(s)＝V_Micro-pores+V_Mesopores。

Of catalystsTotal pore volume (V)_Hole(s)) May be at least 0.4cm³In g, preferably at least 0.5cm³Per g, more preferably at least 0.6cm³A/g, ideally at least 0.7cm³(ii) in terms of/g. Total pore volume (V) of the catalyst_Hole(s)) May be at most 2cm³In g, preferably at most 1.8cm³G, more preferably at most 1.6cm³In g, desirably at most 1.4cm³(ii) in terms of/g. This total pore volume can preferably be measured by nitrogen physisorption using an empirical t-plot method.

Micropore volume (V) of catalyst_Micro-pores) May be at least 0.05cm³Per g, preferably at least 0.08cm³In g, more preferably at least 0.1cm³(ii) in terms of/g. Micropore volume (V) of catalyst_Micro-pores) May be at most 0.4cm³In g, preferably at most 0.3cm³In g, more preferably at most 0.2cm³(ii) in terms of/g. This micropore volume can preferably be measured by nitrogen physisorption using an empirical t-plot method.

In the isomerization catalyst of the invention, the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component. In addition, as described below, the degree of change in such pore properties in% ratio when comparing modified zeolites to unmodified zeolites can indicate the amount of structural change that occurs within the zeolite. Micropore volume (V)_Micro-pores) May be the total pore volume (V)_Hole(s)) At least 2%, preferably at least 4%, more preferably at least 6%, in particular at least 8%. Micropore volume (V)_Micro-pores) May be the total pore volume (V)_Hole(s)) At most 45%, preferably at most 40%, more preferably at most 30%, in particular at most 25%.

In the isomerization of fatty acids (and/or alkyl esters thereof) to branched fatty acids, the high rate of formation of branched fatty acids is coupled with a high total surface area of catalyst or total NH of catalyst₃The absorption properties are not directly related. Surprisingly, it has been found that the surface area (in m) of the membrane is not critical²S is/g_{Outer cover}) And the density of strongly acidic sites (strong NH in. mu. mol/g)₃Absorption) properties are combined into active factors, higher yields of branched chain fatty acids can be obtained. The activity factor is calculated according to the general formula (I):

active factor ═ S_{Outer cover}X strong NH₃Absorption (I)

Wherein "S_{Outer cover}"is the external surface area of the zeolite in m²(ii) per gram, as determined by nitrogen physisorption; and "strong NH₃Absorption "refers to the desorption of NH from the zeolite at a temperature of 327-550 ℃ during temperature programmed desorption of ammonia₃Amounts, in. mu. mol/g.

The catalysts of the invention have an activity factor, calculated on the general formula (I), of at least 30,000, preferably at least 40,000, more preferably at least 50,000, in particular at least 60,000, ideally at least 70,000, in particular at least 80,000. The catalyst of the invention may have an activity factor of at most 200,000, preferably at most 180,000, more preferably at most 160,000, in particular at most 140,000.

Process for preparing zeolites

The present invention also provides a process for preparing a suitable isomerized zeolite catalyst. Different methods can be used to obtain the zeolite of the invention. Suitable methods can be broadly divided into two categories-direct synthesis and post-synthesis modification. Post-synthesis modification methods are preferred for introducing mesopores and/or macropores to enhance diffusion from the zeolite outer surface to existing micropores. Another benefit of this process is the ability to use a wide variety of existing zeolites as starting materials.

Accordingly, the present invention provides a method of modifying the structure of a zeolite comprising the steps of:

i) contacting the zeolite with an alkaline solution preferably comprising NaOH;

ii) contacting the zeolite with an acidic solution preferably comprising HCl; and

iii) contacting the zeolite with an ion exchange material.

The ion exchange material may suitably be an ion exchange resin or an ion exchange solution. Preferably, an ion exchange solution is used, and said ion exchange solution preferably comprises NH₄NO₃。

Preferably, the basic solution and/or the acidic solution and/or the ion exchange solution are used in a concentration of less than 1M (mole). The concentration of the alkaline solution may be 0.1-2M, preferably 0.2-1.5M, more preferablyIs selected from 0.3-0.9M. The concentration of the acidic solution may be 0.05-0.5M, preferably 0.05-0.2M. The concentration of the ion exchange solution may be 0.05 to 0.5M, preferably 0.05 to 0.2M. The alkaline solution may consist of NaOH and water. The acidic solution may consist of HCl and water. The ion exchange solution may be made of NH₄NO₃And water.

The method preferably further comprises the steps of:

iv) calcining the zeolite at a temperature of at least 400 ℃ for at least 2 hours.

The zeolites described herein are obtainable, and preferably are obtained, by the process described herein, i.e. known zeolites are selected and modified according to the process to make them suitable for use as isomerization catalysts in the present invention. Preferably, the unmodified zeolite comprises a ZSM-5 structure, and this structure is maintained in the modified zeolite. The modified zeolite obtainable or obtained by said process preferably comprises micropores and mesopores, wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

The method of modifying the zeolite may comprise increasing the external surface area of the zeolite. The method may include increasing the mesopore volume of the zeolite. The method may include reducing the micropore volume of the zeolite as a percentage of the total pore volume, i.e., V_Micro-pores/V_Hole(s)Percentage of (c).

Production method of branched chain fatty acid

The present invention provides a process for the production of branched fatty acids from a starting material (feedstock) comprising fatty acids, comprising the steps of:

i) contacting a starting material comprising unsaturated fatty acids with a catalyst; and

ii) isomerizing an amount of unsaturated fatty acids using a catalyst to form a composition comprising branched fatty acids;

The starting material for the starting material (raw material) used in the present invention is preferably a naturally occurring material such as triglyceride oil, and may be of animal origin (such as tallow) or more preferably of vegetable origin. Suitable fatty acids include sunflower fatty acid, soybean fatty acid, olive fatty acid, rapeseed fatty acid, linseed fatty acid, cottonseed fatty acid, safflower fatty acid, tall oil fatty acid, and tallow oleic acid. Relatively pure unsaturated fatty acids, such as oleic, linoleic, linolenic, palmitoleic, erucic, and elaidic acids, can be isolated and used, or relatively impure mixtures of unsaturated fatty acids can be used. The unsaturated fatty acids in the starting material may comprise high oleic sunflower fatty acids. The unsaturated fatty acids may be partially hydrogenated. For example, the unsaturated fatty acids in the starting material may comprise partially hydrogenated olive oil or olive fatty acids.

Alkyl esters may be present in the starting material. When alkyl esters are used in the starting materials, the starting materials comprise at least one alkyl ester of an unsaturated fatty acid as described herein. When the mixture of materials present in the starting material comprises alkyl esters, the content of alkyl esters of unsaturated fatty acids described herein is preferably greater than 50 wt%, more preferably greater than 80 wt%, and especially greater than 90 wt% of the starting material.

The starting material suitably comprises C₁₂-C₂₄Unsaturated fatty acids, preferably C₁₄-C₂₂Unsaturated fatty acid, more preferably C₁₆-C₂₂Unsaturated fatty acids, especially C₁₈Or C₂₂Unsaturated fatty acids, and in particular C₁₈Unsaturated fatty acids.

The starting material suitably comprises more than 70%, preferably more than 80%, more preferably more than 90%, in particular more than 95% and especially more than 97% by weight of fatty acids. The starting material suitably comprises (i) greater than 70%, preferably greater than 75%, more preferably from 80 to 99%, particularly from 85 to 97% and especially from 90 to 95% by weight of unsaturated fatty acids, based on the total weight of fatty acids present; and/or (ii) less than 30%, preferably less than 25%, more preferably from 1 to 20%, in particular from 3 to 15% and especially from 5 to 10% by weight of saturated fatty acids.

The unsaturated fatty acid component comprises at least one olefinic double bond, but may comprise two or even three double bonds. The unsaturated fatty acid component suitably comprises, based on total weight of unsaturated fatty acids present: (i) more than 50 wt.%, preferably more than 60 wt.%, more preferably from 80 to 100 wt.%, in particular from 85 to 98 wt.% and in particular from 90 to 95 wt.% of fatty acids having one double bond; and/or (ii) less than 50 wt.%, preferably less than 40 wt.%, more preferably from 0 to 20 wt.%, in particular from 2 to 15 wt.% and in particular from 5 to 10 wt.% of fatty acids having 2 or 3, preferably 2, double bonds.

The catalyst of step ii) is suitably an isomerisation catalyst as described herein. The catalyst is preferably a zeolite or zeolite-like material. Most preferably, zeolites can be used as isomerization catalysts.

The catalyst may be used in a concentration (loading) of at least 0.1 wt%, preferably at least 0.2 wt%, more preferably at least 0.6 wt%, especially at least 0.8 wt%, based on the total weight of fatty acids in the starting material. The catalyst may be used in a concentration (loading) of at most 10 wt%, preferably at most 8 wt%, more preferably at most 6 wt%, in particular at most 4 wt%, ideally at most 2.8 wt%, especially at most 2.4 wt%, possibly at most 1.8 wt%, based on the total weight of fatty acids in the starting material.

The isomerization reaction in step ii) may be carried out for (a duration of) at least 0.5 hour, preferably at least 1 hour, more preferably at least 2 hours, in particular at least 3 hours, ideally at least 5 hours, in particular at least 6.25 hours. The isomerization reaction in step ii) can be carried out for up to 15 hours, preferably up to 12 hours, more preferably up to 10 hours, in particular up to 8 hours.

The isomerization reaction in step ii) may be carried out at a temperature of at least 180 ℃, preferably at least 210 ℃, more preferably at least 240 ℃, in particular at least 250 ℃. The isomerization reaction can be carried out at a temperature of at most 340 ℃, preferably at most 300 ℃, more preferably at most 280 ℃, in particular at most 270 ℃.

The process may be carried out in a closed system, preferably a batch system, for example in an autoclave in which the system is pressurizable. The pressure is suitably 2 to 50kgf/cm². The reaction mixture may be flushed (purged) with a gas such as nitrogen or hydrogen and allowed to rise in pressureNitrogen is preferably used because of its inert nature. A closed system is used to prevent evaporation of water, alcohol and any other low boiling point materials in the system, including those contained in the catalyst.

The isomerization reaction of step ii) may be carried out in the presence of water or a lower alcohol. This is to suppress the formation of acid anhydride due to dehydration or dealcoholization of the starting material. When the starting material is mainly an unsaturated fatty acid, it is preferable to add water; and when the starting material is mainly an alkyl ester of an unsaturated fatty acid, it is preferable to add a lower alcohol. The lower alcohols used suitably contain 1 to 3 carbon atoms, particularly preferably methanol, ethanol and propanol. The lower alcohol preferably has the same alkyl group as the fatty acid ester of the starting material.

The isomerization reaction may be carried out in the absence of a Lewis base, and the isomerization reaction mixture preferably does not contain a Lewis base. Alternatively, the isomerization reaction may be carried out in the presence of a Lewis base, and in this case the Lewis base may be an amine or a phosphine, in particular an organic amine or an organic phosphine, in particular triphenylphosphine.

The conversion (i.e. the weight percentage of unsaturated fatty acids in the starting material reacted in the isomerization reaction) may be at least 20 wt%, preferably at least 30 wt%, more preferably at least 40 wt%, in particular at least 50 wt%, ideally at least 60 wt%, based on the initial weight of unsaturated acids. The conversion may be up to 98 wt.%, preferably up to 95 wt.%, in particular up to 90 wt.%.

After 6.25 hours of isomerization, the composition comprising branched fatty acids preferably comprises at least 20 wt% branched fatty acids.

Further process steps may be employed to purify or modify the fatty acid product. Additionally, the isomerization catalyst may be removed. These further method steps will be discussed below.

In a further step the oligomerized fatty acid may be removed from the composition comprising branched fatty acids, for example by vacuum distillation. This step may be carried out at temperatures up to 230 ℃. This step can be carried out at less than 10 mbar. When a subsequent hydrogenation step (as described below) is employed, the oligomerized fatty acid can then be removed prior to hydrogenation.

The isomerization catalyst may be separated from the composition, for example, by filtration, preferably using a pressurized filtration unit with a box depth filter, and preferably reused as described herein. When a hydrogenation step (described below) is employed, the hydrogenation catalyst can be separated from the composition in the same manner; preferably, the hydrogenation catalyst may be used after removal of the isomerization catalyst to facilitate recovery, reuse, or recycling of the different catalysts. Alternatively, one or more of the isomerization and hydrogenation catalysts may be provided in a fixed bed arrangement, thereby reducing the catalyst separation requirements.

The composition comprising branched fatty acids produced in step ii) is optionally also hydrogenated, for example by known methods in an autoclave, for example a method using a hydrogenation catalyst, in particular a metal hydrogenation catalyst. Catalysts for hydrogenation are well known and may be homogeneous or heterogeneous (i.e., the catalyst exists in a different phase (typically a solid phase) relative to the reactant/product stream or matrix (typically a liquid phase). Useful metal hydrogenation catalysts include nickel, copper, palladium, platinum, molybdenum, iron, ruthenium, osmium, rhodium, iridium, zinc or cobalt, and in particular zinc. Combinations of catalysts may also be used. Bimetallic catalysts such as palladium-copper, palladium-lead, nickel-chromite may be used.

The metal hydrogenation catalyst may be used with a promoter, which may or may not be another metal. Typical metal catalysts containing promoters include, for example: nickel with sulfur or copper as a promoter; copper with chromium or zinc as a promoter; zinc with chromium as promoter; or carbon supported palladium with silver or bismuth as promoters.

In one embodiment, a nickel catalyst that has been chemically reduced to an activated state with hydrogen may be used as a hydrogenation catalyst. Commercial examples of supported nickel hydrogenation catalysts include those available under the trade names "Nysofact", "nyssel" and "NI 5248D" (available from Engelhard Corporation). Other supported nickel hydrogenation catalysts include those available under the trade designation "Pricat^TM 9910"、"Pricat^TM 9920"、"Pricat^TM9908 "and" Pricat^TM9936 "(available from Johnson Matthey).

Suitable metal hydrogenation catalysts may be used as a fine dispersion (slurry environment) in the hydrogenation reaction of the present invention. For example, in some embodiments, particles of the supported nickel catalyst are dispersed in a protective medium comprising hardened triacylglycerides, edible oil, or tallow. The supported nickel catalyst may be dispersed in the protective media at a concentration of about 22 wt% nickel.

The hydrogenation catalyst may be impregnated on a solid support. Some useful supports include carbon, silica, alumina, magnesia, titania and zirconia. Examples of supported catalysts include: palladium, platinum, rhodium or ruthenium on a carbon or alumina support; nickel on a magnesia, alumina or zirconia support; palladium on a barium sulfate support; or copper on a silica support. The hydrogenation catalyst may be a supported nickel or sponge nickel type catalyst. In some embodiments, the catalyst comprises nickel provided on a support that has been chemically reduced to an active state with hydrogen (i.e., reduced nickel). The support may comprise porous silica (e.g. diatomaceous earth) or alumina. These catalysts are characterized by a high nickel surface area per gram of nickel.

The hydrogenation catalyst is suitably used in a concentration of less than 10 wt%, preferably less than 5 wt%, more preferably less than 3 wt%, specifically 0.5 to 2 wt% and especially 0.8 to 1.2 wt% based on the weight of the composition.

In addition, compositions comprising branched chain fatty acids may optionally be treated to separate branched and straight chain fatty acids. After removal of the straight chain fatty acid fraction by the separation step, the final product composition may be produced, that is, the composition may be refined, with the need for refined product depending on its intended end use. The separation step may comprise a solvent-based process, a wet separation process (with water and surfactant) or a dry separation process. Each of these processes is capable of removing straight chain fatty acid fractions to produce the final product composition.

Compositions comprising branched chain fatty acids

There is provided a composition comprising branched fatty acids obtainable and preferably obtained by the above process.

The composition may comprise a branched fatty acid and a catalyst as described herein. Where the catalyst is a zeolite catalyst as described herein, it has been found that the presence of the zeolite catalyst has no detrimental effect on downstream applications of the branched fatty acid composition. It may be preferred to reduce the concentration of the catalyst (zeolite) by an active catalyst removal step as described above to provide a higher purity fatty acid product.

The composition may suitably comprise at least 20 wt%, preferably at least 30 wt%, more preferably at least 35 wt%, in particular at least 40 wt%, ideally at least 42 wt%, especially at least 44 wt% branched fatty acid, preferably C18 branched fatty acid. The composition may comprise up to 90 wt%, preferably up to 80 wt%, more preferably up to 70 wt% branched fatty acid, preferably C18 branched fatty acid.

The composition may comprise at least 1 wt.%, preferably at least 2 wt.%, more preferably at least 5 wt.%, in particular at least 10 wt.%, in particular at least 12 wt.% of oligomeric fatty acids such as dimer and trimer acids. The composition may comprise up to 30 wt%, preferably up to 25 wt%, more preferably up to 20 wt% of an oligomerised fatty acid. Alternatively, the composition may comprise less than 5 wt%, preferably less than 2 wt%, more preferably less than 1 wt% of an oligomerised fatty acid.

The final product composition preferably has: (i)145-210, more preferably 160-205, in particular 175-200 and in particular 185-195mgKOH/g (as measured herein), and/or (ii)165-220, more preferably 175-210, in particular 185-200 and in particular 190-195mgKOH/g (as measured herein), and/or (iii) an unsaponifiable content of less than 10, more preferably less than 5, in particular 1.0-3 and in particular 1.5-2g/100g (as measured herein), and/or (iv) an iodine value of less than 5, more preferably less than 3, in particular 1-2 and in particular 1g iodine/100 g (as measured herein), and/or (v) -10 to 25 ℃, more preferably-5 to 20 ℃, in particular 0-10 ℃ and in particular 3-6 ℃ (as measured herein), and/or (vii) a color (measured as described herein) of less than 200, more preferably less than 150, particularly less than 100 and especially less than 75Hazen units.

Typical final product compositions are as follows:

use of isomerization catalysts

The invention also provides the use of a catalyst for the production of branched fatty acids from a feedstock comprising unsaturated fatty acids, the catalyst comprising micropores and mesopores, and wherein the micropore volume (V)_Micro-pores) Is the total pore volume (V) of micropores and mesopores_Hole(s)) 1-50% of the total amount of the active component.

The catalyst is preferably a zeolite as described herein.

Any or all of the features described herein and/or any or all of the steps of any of the methods or processes described herein may be applied in any combination in any aspect of the invention.

Examples

The invention is illustrated by the following non-limiting examples. Unless otherwise indicated, all parts and percentages are given on a weight basis.

It is understood that all physical property tests are conducted at atmospheric pressure and room temperature (i.e., about 20 ℃) unless otherwise indicated herein or unless otherwise indicated in the test methods and procedures referred to.

Test method

The following test methods are applied in this specification:

(i) acid value

Acid number was measured using the american petroleum chemist association (a.o.c.s.) official method Te1a-64 (re-approved in 1997) and expressed as milligrams of potassium hydroxide required to neutralize free fatty acids in a 1 gram sample.

(ii) Saponification number

The saponification value was determined using the official method of a.o.c.s. Tl 1a-64(1997) and is defined as the number of milligrams of potassium hydroxide reacted with 1 gram of sample under the specified conditions.

(iii) Unsaponifiable number

Unsaponifiable values are measured using the official method of A.O.C.S. Ca6b-53 (1989).

(iv) Iodine number

Iodine value is determined using the Wijs method, official method of a.o.c.s. Tg 1-64(1993), and is expressed as grams of iodine absorbed by a 100 gram sample under the specified test conditions.

(v) Cloud point

The cloud point was measured by the official method of A.O.C.S. (Cc 6-25).

(vi) Point of solidification

The curing point was measured by the official method of a.o.c.s. (Cc 12-59).

(vii) Colour(s)

Colour is determined in Hazen units (Pt-Co scale) using ISO 2211(1973) colour determination.

(viii) Fatty acid composition

The composition of the fatty acids (chain length, saturated/unsaturated, linear/branched) was determined using gas chromatography, using method ISO 5508:1990(E) animal and vegetable fats and oils-fatty acid methyl esters were analyzed by gas chromatography. To simplify the compositional analysis, the analysis was performed on a laboratory scale after hydrogenation.

(ix) Zeolite pore volume and surface area

The following zeolite properties were measured by low temperature nitrogen physisorption using a Quantachrome Autosorb 6B automatic adsorption analyzer. Before these measurements were performed, the samples were degassed at 350 ℃ for about 16h in vacuo.

The specific surface area was measured according to ISO 9277. Total surface area (S) was determined based on BET (Brunauer-Emmett-Teller) theory_{General assembly}). Micropore surface area (S) from nitrogen physisorption data based on empirical t-plot method_Micro-pores). External surface area (S)_{Outer cover}) I.e. the sum of the surface areas of mesopores + macropores, is obtained by subtracting the calculated micropore surface area from the total surface area, i.e. (S)_{Outer cover})＝(S_{General assembly})-(S_Micro-pores)。

Determination of total pore volume (V) by Nitrogen physisorption_Hole(s)). Micropore volume (V) from nitrogen physisorption data based on empirical t-plot method_Micro-pores). Mesopore volume (V)_Mesopores) Obtained by subtracting the calculated micropore volume from the total pore volume, i.e. (V)_Mesopores)＝(V_Hole(s))-(V_Micro-pores)。

(x) Zeolite acid sites

A measure of the acid sites in the zeolite was determined by the ammonia Temperature Programmed Desorption (TPD) method. The Instrument used was an automated chemisorption analyzer model TPD/TPR2900 supplied by Micromeritics Instrument Corporation. The pretreatment of the sample before measurement comprises:

1. drying by heating to 550 ℃ under helium,

2. cooling to 200 deg.C (473K) under helium,

3. adsorb ammonia at 200 ℃ (473K) and desorb all physisorbed ammonia at the same temperature.

The measurement procedure includes:

1. a ramp rate of 10K/min was applied in helium to heat the sample from room temperature to 550 ℃ (823K); the sample was held at 823K for 30 minutes in flowing helium and then cooled to 200 deg.C (473K) in helium;

2. the sample was then rinsed with ammonia for 10 minutes and helium for 10 minutes. This procedure was repeated 3 times. After the third washing step, the sample was held constant until a stable baseline was obtained;

3. finally, the desorption of ammonia was monitored over a temperature range of 473-823K (with a temperature rise rate of 10K/min).

The quantities measured were:

A. total NH₃absorption-Up to 550 deg.C (823K) all NH desorbed₃-providing a measure of the total number of acid sites;

B. strong NH₃Absorb NH desorbed between 327 and 550 ℃ (600 and 823K)₃-providing a measurement of the amount of strong acid sites.

Ammonia desorbed at temperatures below 600K is considered to be ammonia adsorbed to weakly acidic sites. The ammonia desorbed at the temperature of 327-.

Zeolite sample

Three samples of commercially available ZSM-5 type zeolites were obtained having the characteristics shown in table 2.

TABLE 2

ZSM-5 type zeolite	SAR	Approximate crystal size	Testing isomerization Performance
				Zeolite A	27	1000nm	Comparative example 3
Zeolite B	23	250nm	Comparative example 6
				Zeolite C	80	500nm	Comparative example 9

The silica/alumina ratio (SAR) values and the crystallite sizes of these zeolite catalysts are published by the suppliers.

Example 1: modification of zeolite A-base and acid treatment

180ml of a 0.7M NaOH solution were heated to 65 ℃ in a round-bottomed flask equipped with a stirrer. 6g of zeolite A were added. After 2 hours of this alkali treatment, the mixture was washed with ice-waterThe reactor is immersed in the mixture for quenching. The zeolite was separated from the solution by centrifuging the mixture at 4000rpm for 10 minutes, followed by washing with distilled water to neutral pH and drying. The dried zeolite was acid washed 2 times with 0.1M HCl solution over 5h at 65 ℃. The zeolite was separated from the solution by centrifuging the mixture at 4000rpm for 10 minutes, followed by washing with distilled water to neutral pH and drying. After drying, the zeolite was exchanged with 0.1M of an ion exchange solution NH₄NO₃The treatment was carried out for 4 cycles, 6h, 16h, 6h and 16h respectively. After each cycle, the zeolite was isolated by filtration and resuspended in fresh ion exchange solution. The zeolite is then washed with distilled water to neutral pH and dried. The zeolite was calcined at 500 ℃ for 5 hours before use.

The resulting modified catalyst is referred to as zeolite Mod a.

Example 2: isomerization of fatty acids with zeolite Mod A

25g of high oleic sunflower fatty acid (containing 4 wt% C16:0, 2.6 wt% C18:0, 81.4 wt% C18:1 and 9.7 wt% C18:2 fatty acid), 0.25g of zeolite Mod A (from example 1) and 0.4g of water were charged to a 50ml autoclave. 0.25g of zeolite in 25g of fatty acid is equivalent to 1 wt% of zeolite, based on the total weight of fatty acids in the starting material. The reaction mixture was flushed 3 times with nitrogen and pressurized to 1bar with nitrogen. The reaction mixture was heated to 260 ℃. After 5.5 hours, the reaction mixture was cooled to 80 ℃ and filtered through filter paper. The resulting filtrate was analyzed and its composition was as follows: