DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION

(See Section 10 and Rule 13)

Title of invention:
A CATALYST COMPOSITION FOR PRODUCTION OF ALKYL PHENOLS

APPLICANT:
Deepak Nitrite Limited
An Indian entity having address as,
2nd Floor, Fermenter House,
Alembic City, Alembic Avenue Road,
Vadodara – 390 003, Gujarat, India.

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[0001] The present application is based on and claiming priority from Indian provisional Application Number 202421095983 filed on 05th December 2024, the details of which are incorporated herein by a reference.
TECHNICAL FIELD
[0002] The present subject matter described herein, in general, relates to the field of substituted phenols. Particularly, the present disclosure relates to the development of a catalyst composition for the production of substituted alkyl phenols.
BACKGROUND
[0003] Alkylphenols are a group of organic compounds composed of a phenol (aromatic ring with a hydroxyl group) bonded to one or more alkyl groups. These compounds vary in structure, with examples ranging from mono alkyl phenols, like cresols (methyl phenols), to more complex structures, such as trimethylphenols (TMP), where three methyl groups are attached to the phenol ring. Alkylphenols, particularly trimethyl phenol (TMP) are commonly used as intermediates in the production of Vitamin E as major application along with synthesis of other industrial chemicals, such as resins, surfactants, and antioxidants. Due to their effectiveness in enhancing product stability and performance, alkylphenols are widely valued in the chemical, automotive, and materials industries.

[0004] Conventional methods for synthesizing alkyl phenols by alkylating a phenolic compound with methanol as the alkylating agent encounter several efficiency and sustainability challenges. A key issue is the tendency of methanol to crack under reaction conditions, which leads to undesired by-products and a lower yield of alkyl phenols. Although water is co-fed to mitigate methanol cracking and extend catalyst life, this strategy is not entirely effective, as water can also impact the reaction environment.

[0005] Moreover, the catalyst's lifespan and activity are often limited due to deactivation from carbon deposits, requiring frequent regeneration or replacement, which increases operational costs and energy consumption. Additionally, this process may involve high temperatures and pressures, which further contribute to environmental impact and energy inefficiency, challenging the sustainability of the method in large-scale production.

[0006] In conventional processes, the immiscibility of xylenol with water often results in phase separation during the reaction. The reaction mixture is often heterogeneous, which complicates the monitoring and real-time adjustment of parameters like temperature, feed composition, and flow rates. As a result, fluctuations in reaction conditions can occur, leading to variable yields of the desired product and increased formation of byproducts, ultimately raising purification costs and reducing overall process efficiency.

[0007] Traditionally, the synthesis processes for alkyl phenols suffer from inconsistent selectivity due to competing side reactions, often resulting in over-alkylation and various byproducts. These byproducts reduce the overall yield of alkyl phenols and necessitate additional downstream purification steps, which increase operational complexity and costs.

[0008] Alternative routes for producing alkyl phenols, such as recovery from coal tar and petrochemical processes, isomerization of isophorone, and the condensation of diethyl ketone with crotonaldehyde, each come with notable drawbacks. Coal tar and petrochemical recovery methods are often complex and energy-intensive, requiring extensive purification steps due to impurities and resulting in high operational costs. The isomerization of isophorone, while effective for certain phenol types, generally requires high temperatures and pressures, which increase energy demand and equipment wear, impacting both economic and environmental sustainability.
[0009] Additionally, this method may produce unwanted by-products that necessitate further separation and treatment. The condensation of diethyl ketone and crotonaldehyde offers an alternative pathway but often suffers from low selectivity, resulting in a mix of products that require additional processing to isolate the desired alkyl phenol. Also, hydrodeoxygenation of biomass-derived phenolic compounds offers a sustainable pathway but is constrained by the variability in biomass quality and typically requires expensive catalysts and hydrogen, raising operational costs. The Friedel-Crafts alkylation with alkyl halides is effective but generally produces a range of by-products due to lack of selectivity and often involves hazardous acid catalysts that require careful handling and disposal.

[0010] Hydro-alkylation of aromatic compounds is more selective but relies on high pressures and specific catalysts, which can be costly and environmentally taxing. Catalytic cracking of hydrocarbons with phenols is another option but suffers from poor selectivity, as controlling the reaction to yield only desired alkyl phenols is challenging, leading to inefficiencies. Additionally, aromatic rearrangement and cyclization of phenolic compounds can yield specific isomers but typically demand precise reaction conditions, and the limited scope of rearrangements often restricts its applicability to only certain types of alkyl phenols. These routes, while varied, tend to be limited by challenges in yield, product purity, and scalability, making them less viable for large-scale, sustainable production of alkyl phenols.

[0011] In addition to product inconsistency, the conventional process is operationally complex and requires precise control of reaction conditions to maintain high selectivity of alkyl phenols. Fluctuations in these conditions can result in inconsistent yields and varying product quality.

[0012] Also, mechanical integrity of a catalyst is essential in sustaining its performance and efficiency. For a catalyst to consistently facilitate this reaction without degradation, it must maintain stability over multiple cycles of use. Factors like high temperatures, pressure, and exposure to reactive compounds during alkylation can cause catalysts to lose their mechanical integrity, leading to powder formation, fouling of equipment, higher pressure drop across the reactor diminished activity, selectivity, and eventually deactivation. This breakdown affects reaction efficiency, potentially leading to unwanted byproducts and lower yield.

[0013] Therefore, there is a long-felt need to develop a catalyst composition for the production of alkyl phenols to overcome the existing challenges mentioned above. Further, the present disclosure addresses the need for a catalytic composition for production of alkyl phenols designed to achieve superior performance in the reaction, offering enhanced yield, high conversion rates, improved selectivity, extended stability, and good mechanical integrity.
SUMMARY
[0014] Before the present system and its components are described, it is to be understood that this disclosure is not limited to the particular system and its arrangement as described, as there can be multiple possible embodiments which are not expressly illustrated in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only and is not intended to limit the scope of the present application. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in detecting or limiting the scope of the claimed subject matter.

[0015] As disclosed herein, the present subject matter relates to a catalyst composition for production of alkyl phenols.

[0016] In one implementation, a catalyst composition for production of alkyl phenols is disclosed. The catalyst composition comprises of an active phase present in an amount in the range of 80% - 99 %w/w. The catalyst composition comprises of one or more promoters present in the range of 10 - 30 %w/w. Further, the catalyst composition comprises of a binder component present in the range of 5% - 35% w/w of the active phase.
BRIEF DESCRIPTION OF FIGURES
[0017] The detailed description is described with reference to the accompanying Figures. In the Figures, the left-most digit(s) of a reference number identify the Figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

[0018] Figure 1 depicts a chromatogram for screening of bentonite as a binder with catalyst which demonstrates high selectivity of 2,3,6-trimethyl phenol (TMP) as compared to trace level components, in accordance with an embodiment of the present disclosure.

[0019] Figure 2 depicts a graphical representation of screening of catalyst composition at an extended time of 572 hrs which demonstrates the stability of catalyst composition, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0020] Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
[0021] The words “comprising”, “having”, “containing”, and “including”, and other forms thereof are intended to be equivalent in meaning and be open-ended in that an item or items following any one of these words is not meant to be exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Although any methods similar or equivalent to those described herein may be used in the practice or testing of embodiments of the present disclosure, the exemplary methods are described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0022] Various modifications to the embodiment may be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, a skilled person in the art may readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein. A detailed description of the invention will be described hereinafter.
[0023] The present disclosure relates to a catalyst composition for production of alkyl phenols. The disclosed catalyst composition for production of alkyl phenols offers several advantages including high selectivity for the target product, such as alkyl phenols, and reduced alkylating agent decomposition. The catalyst composition demonstrates optimal conversion efficiency, especially when modified with clay, which enhances its performance. Additionally, the catalyst composition provides improved operational simplicity, allowing for precise monitoring of both conversion and selectivity. The catalyst composition also enhances the mechanical integrity reusability, stability, and extended lifespan, contributing to cost-effectiveness and environmental sustainability in the production process.
[0024] In an embodiment of the present subject matter, a method for production of alkyl phenols is disclosed. The method may comprise a step of alkylation of a phenolic compound in presence of an alkylating agent at 200°C-700°C by using the catalyst composition as discussed herein. Preferably, the of alkylation of a phenolic compound is carried out at a temperature in the range between 300-400°C.
[0025] The of alkylation of a phenolic compound may comprise a liquid hourly space velocity (LHSV) of 0-10. Preferably, the alkylation of a phenolic compound may comprise a liquid hourly space velocity (LHSV) of 2-8.
[0026] In an embodiment the alkyl phenols obtained from the alkylation of phenolic compounds may be at least one, but not limited to, methyl phenol (cresol), dimethyl phenol (xylenol), and trimethyl phenol (TMP). Preferably the alkyl phenol is trimethyl phenol (TMP).
[0027] In an embodiment the phenolic compound may be selected from 2,3-xylenol, 2-methylphenol (cresol), 2,4-dimethylphenol, and 3,4-dimethylphenol. Preferably the phenolic compound is 2,3-xylenol.
[0028] In an embodiment the alkylating agent may be selected from methanol, dimethyl ether, dimethyl carbonate, and methyl chloride (chloromethane). In a preferred embodiment, the alkylating agent is methanol.
[0029] In one embodiment of the present disclosure, a catalyst composition for production of alkyl phenols is disclosed. The composition includes a metal or metal oxide as the active catalyst, combined with a binder to enhance mechanical integrity and prevent fragmentation under high temperature and pressure. The composition also incorporates a promoter to improve selectivity and yield, reducing undesired by-products. The composition is optimized for ensuring consistent performance over multiple cycles and minimizing the need for frequent replacements, thus improving operational efficiency and sustainability in alkyl phenol production.
[0030] In one embodiment of the present disclosure, the catalyst composition is a catalyst composite, combining metal or metal oxide as the active catalyst with a binder and promoter to enhance mechanical integrity, selectivity, and yield of the alkyl phenol.
[0031] In an embodiment, the catalyst composition may comprise of an active phase present in an amount in the range of 80% - 99 %w/w. Preferably, an active phase present in an amount in the range of 85 - 95 %w/w.
[0032] In a related embodiment, the active phase is iron oxide (Fe2O3) selected for its effective catalytic properties in the production of alkyl phenols. Iron oxide is a widely studied material due to its stability, cost-effectiveness, and ability to promote key reaction steps such as alkylation while maintaining high selectivity and conversion rates. When used in the catalyst composition, iron oxide enhances the efficiency of the reaction by facilitating the activation of reactants and reducing the formation of undesirable by-products. Its use also contributes to the catalyst's long-term stability, as iron oxide is less prone to deactivation compared to other metal-based catalysts. Additionally, iron oxide can be easily regenerated, improving the catalyst's lifespan and reducing operational costs.
[0033] In another embodiment, the catalyst composition may comprise various promoters that enhance its catalytic efficiency and overall performance. In an embodiment, the catalyst composition may comprise of one or more promoters present in the range of 10% - 30%w/w. Preferably, the one or more promoters present in the range of 15% - 25%w/w.
[0034] In a related embodiment, the one or more promoters such as L1, L2 and L3 are metal oxide promoters selected from silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O).
[0035] For instance, various combinations of the promoters L1, L2, and L3 are utilized to enhance the catalytic performance. These combinations may include, but are not limited to, combinations of L1 as SiO2, L2 as Cr2O3, and L3 as K2O to synergistically improve catalytic activity and stability.
[0036] In a related embodiment, the catalyst and promoters have a molar ratio of Fe2O3: L1: L2: L3 is in the range of 200:5:1:0.05 to 50:5:1:0.01. Preferably the catalyst and promoters have a molar ratio of 100:2:1:0.1, in which Fe2O3 active phase at a value of 100, L1 value is 2, L2 value is 1, and L3 value is 0.1.
[0037] Promoters are preferably at least one of silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O) are incorporated into the composition to support and amplify the activity of the active phase, iron oxide (Fe2O3). Each promoter serves a unique function: SiO2 acts as a structural stabilizer, helping maintain the catalyst's integrity under high-temperature conditions; Cr2O3 contributes to increased redox activity, which boosts the catalyst’s ability to facilitate reactions efficiently; and K2O improves the selectivity by optimizing the chemical environment of the catalyst. Together, these promoters interact synergistically with Fe2O3 to improve conversion rates, selectivity, and stability. This enhanced catalyst composition demonstrates improved resistance to deactivation, increased longevity, and reduced formation of unwanted by-products, making it highly suitable for the consistent and efficient production of alkyl phenols.
[0038] In a preferred embodiment, the catalyst composition is precisely formulated with a molar ratio of 100:2:1:0.1, specifically designed to optimize the catalytic process for high conversion efficiency in synthesizing alkyl phenols, such as 2,3,6-trimethylphenol (TMP). In this formulation, iron oxide (Fe2O3) constitutes the primary component, providing the main catalytic activity needed for the reaction.
[0039] In another related embodiment, the catalyst composition may be modified with the modifier/binder (B) to further enhance its performance and efficacy in the production of alkyl phenols, such as 2,3,6-trimethylphenol (TMP). This modifier/binder can include a variety of materials, each chosen for its unique properties that contribute to the overall functionality of the catalyst.
[0040] In an embodiment, the catalyst composition may comprise of a binder component present in the range of 5% - 35% w/w of the active phase. Preferably, the catalyst composition may comprise of a binder component present in the range of 10% - 25% w/w.
[0041] In a related embodiment, the binder component B is enabled for shaping the catalyst and maintaining mechanical integrity of the catalyst. The binder component B ensures that the active catalytic material is held together in a stable form, allowing the catalyst to maintain its structural integrity during the reaction. This is particularly important in high-temperature reactions, where the catalyst may experience thermal stresses or mechanical abrasion. The binder component B not only facilitates the moulding of the catalyst into desired shapes (such as pellets, extrudates, or tablets) but also prevents particle breakage or deformation, ensuring consistent surface area and catalytic activity.
[0042] In a related embodiment, the binder B is selected from at least one of attapulgite, kaolin, bentonite clay, montmorillonite, palygorskite, cellulose, zeolite, hectorite, and the like. In a preferred embodiment, the binder component B is selected from the group consisting of bentonite, attapulgite, and kaolin.
[0043] In a related embodiment, the catalyst, promoters and binder component Fe2O3: SiO2:Cr2O3: K2O: B having a molar ratio in the range of 200: 5: 1: 0.05: 20.6 to 50: 5: 1: 0.01: 5.6. In a preferred embodiment, the catalyst, promoters and binder component Fe2O3: SiO2:Cr2O3: K2O: B having a molar ratio 100: 2: 1: 0.1: 10, in which Fe2O3 active phase at a value of 100, L1 value is 2, L2 value is 1, and L3 value is 0.1 and B value is 10.
[0044] This binder helps maintain the physical integrity of the catalyst under high temperatures and pressures often encountered in alkylation, preventing particle disintegration and ensuring a longer lifespan for the catalyst. Preferably, the binder may include bentonite clay for its proven effectiveness in stabilizing catalyst structure. The binder component B is included in the catalyst composition to hold the catalyst together, ensuring structural integrity and facilitating the efficient application of the catalyst in the desired reaction. Together, these components work synergistically to improve the catalyst's overall effectiveness in various industrial processes.
[0045] Additionally in an embodiment, the catalyst composition may comprise an auxiliary promoter such as A1, A2 which are substances added to enhance the catalyst's performance. These auxiliary promoters help optimize the catalytic activity by influencing reaction rates or selectivity.
[0046] In a related embodiment, A1 is selected from the group consisting of manganese oxide (MnO2), cerium oxide (CeO2), and zirconium oxide (ZrO2), each providing distinct catalytic properties such as enhanced oxidation activity, redox cycling, or thermal stability. A2 is selected from the group consisting of zinc oxide (ZnO), magnesium oxide (MgO), and lanthanum oxide (La2O3), which act as auxiliary promoters to further optimize the catalyst's performance. Zinc oxide (ZnO) promotes dehydrogenation reactions, magnesium oxide (MgO) provides basicity, and lanthanum oxide ((La2O3) enhances thermal stability and oxygen storage capacity.
[0047] Various combinations of components like Fe2O3, SiO2, Cr2O3, K2O, and A1 (such as MnO2, CeO2, or ZrO2) can be used to customize the catalyst composition. The Fe2O3: SiO2: Cr2O3: K2O: MnO2 is suitable for applications requiring high oxidation activity, while Fe2O3: SiO2: Cr2O3: K2O: CeO2 can enhance redox cycling in processes like catalytic converters. Fe2O3: SiO2: Cr2O3: K2O: ZrO2 is ideal for high-temperature reactions where thermal stability is crucial.
[0048] Further, the combination of components like Fe2O3, SiO2, Cr2O3, K2O, and A2 (such as MnO2, CeO2, or ZrO2) can be further optimized by incorporating auxiliary promoters like ZnO, MgO, and La2O3 to enhance catalytic performance. For example, Fe2O3: SiO2: Cr2O3: K2O: ZnO improves dehydrogenation and oxidation reactions, while Fe2O3: SiO2: Cr2O3: K2O: MgO boosts basicity and stabilizes active sites for enhanced reaction efficiency. Fe2O3: SiO2: Cr2O3: K2O: La2O3 improves thermal stability and oxygen storage capacity, making it suitable for high-temperature processes.
[0049] Furthermore, the combination of Fe2O3: SiO2: Cr2O3: K2O: A1: A2 can be used. For instance, composition such as Fe2O3: SiO2: Cr2O3: K2O: MnO2: ZnO would optimize oxidation reactions, improve structural stability, and enhance dehydrogenation performance. Other possible combinations include Fe2O3: SiO2: Cr2O3: K2O: CeO2: MgO for improved redox cycling and thermal stability, or Fe2O3: SiO2: Cr2O3: K2O: ZrO2: La2O3, which would enhance thermal stability and oxygen storage properties for high-temperature applications.
[0050] In one embodiment, the catalyst composition comprises a primary combination having active phase as iron (Fe) along with promoters (L1, L2, and L3) such as chromium (Cr), silicon (Si), and potassium (K) based oxides, a binder component B and additional auxiliary promoters (A1 and A2).
[0051] In one embodiment, the binder selected as bentonite clay plays a versatile role in alkylation reactions, serving as the binder and/or modifier, which enhances its value in catalyst formulations. As a binder, bentonite clay provides structural support by helping to hold the catalyst particles together, improving their resistance to the mechanical stress and temperature fluctuations typical in alkylation processes. Its strong binding properties ensure that the catalyst maintains its integrity over time, reducing degradation and extending catalyst life.
[0052] Additionally, bentonite clay can act as the binder/modifier by influencing the catalyst's surface acidity and adsorption properties. Its high surface area and inherent acidity can contribute to improved reaction rates and selectivity, creating favourable conditions for the desired alkylation reactions. This dual function of bentonite clay makes it an advantageous component in catalyst systems, supporting both stability and catalytic performance.
[0053] In an embodiment, the crushing strength of the catalyst composition is 5-14 kgf. In a preferred embodiment, the crushing strength of the catalyst composition is 9-10 kgf.
[0054] This increased strength ensures the catalyst particles can withstand handling, transport, and harsh reactor conditions without breaking or generating fines, which can otherwise lead to reactor inefficiencies. The catalyst composition is a regenerative catalyst composition. Furthermore, the binder (B) such as bentonite offers better thermal stability, making it ideal for high-temperature catalytic processes, while cellulose tends to decompose at elevated temperatures, weakening the catalyst. Additionally, bentonite resists abrasion and is chemically inert, maintaining the catalyst's activity and preventing unwanted interactions with reactants. These properties, combined with its hydration and binding strengths, make bentonite a more reliable and durable binder for catalytic applications, particularly where high mechanical strength and thermal stability are critical. Thus, while cellulose may have certain advantages, such as biodegradability, bentonite is the preferred choice in industrial catalyst preparation due to its superior strength and stability.
[0055] In another preferred embodiment, the process for production of 2,3,6-trimethyl phenol is disclosed. The process comprises alkylating 2,3-xylenol with methanol at a temperature range of 200°C to 700°C using the catalyst composition including iron oxide (Fe2O3) as the active component, enhanced by auxiliary promoters like silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O) that includes the binder and/or the modifier such as bentonite clay is used.
[0056] Further, to achieve a homogeneous feed in the production of 2,3,6-trimethyl phenol, the methanol content is increased to create a specific feed ratio of 2,3-xylenol: methanol: water = from 1:2:0.5 to 1:10:2 and preferably 1:3:0.5 to 1:7:2.
[0057] This adjusted ratio ensures that all components are well-mixed and evenly distributed throughout the reaction medium, promoting consistent reaction conditions. By having methanol present in a higher concentration relative to 2,3-xylenol, the system can maintain optimal reaction kinetics and improve catalyst interaction, enhancing both the conversion and selectivity towards the desired product. Additionally, the presence of water in the mixture may help to moderate the reaction temperature and minimize any unwanted side reactions.
[0058] Examples are set forth below to further illustrate the nature of the disclosure and the manner of carrying it out. However, the disclosure should not be considered as being limited to the details thereof.
Examples:
Example 1: Screening of the catalyst each prepared by incorporating different binder materials
Example 1(a): Cellulose as a binder
The screening of catalyst featuring iron oxide (Fe2O3) as the active component, enhanced by auxiliary promoters like silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O) in a molar ratio ranging from 100:2:1:0.1 with 10% cellulose used as a binder involved a feed mixture of 2,3-xylenol, methanol, and water, with the ratio adjusted from 1:5:1 at different liquid hourly space velocities (LHSV) of 0.5 h-1 and 1.0 h-1. The reaction carried out at 380°C revealed that the conversion of 2,3-Xylenol was consistently high, reaching around 97%, with selectivity towards the desired product 2,3,6-TMP ranging from 95-97%. The selectivity for the undesired 2,5-DMP remained low, at approximately 2-3%.
Example 1(b): Screening of the catalyst each prepared by incorporating different clays Bentonite, Attapulgite, and Kaolin as binders.
The performance of three catalysts, each prepared with different clays (Bentonite, Attapulgite, and Kaolin) as binders in active catalyst formulation featuring iron oxide (Fe2O3) as the active component, enhanced by auxiliary promoters like silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O) in a ratio ranging from 100:2:1:0.1, was evaluated at 360°C and an LHSV of 1.5 h?¹. Reactions were carried out with a feed of 2,3-Xylenol, methanol, and water for 24 hours in a fixed bed reactor (FBR). The catalysts with bentonite and attapulgite as binders achieved conversions of 85-88% with good material balance (~87-88%) and a homogeneous reaction mass, while the Kaolin-based catalyst showed a higher conversion (~93%) but a lower material balance (~76%) and exhibited a two-layer reaction mass, indicating more methanol cracking. The methanol-to-xylenol ratio was also higher for the Kaolin catalyst (3.19) compared to Bentonite (2.3) and Attapulgite (2.7), suggesting increased methanol cracking in the Kaolin catalyst. The lower methanol cracking and better material balance in the Bentonite catalyst make it the most suitable option for an atom-efficient catalytic process.
As a result, the methanol-to-xylenol ratio was 2.3 and 2.7 for the bentonite and attapulgite catalysts, respectively, compared to 3.19 for the kaolin catalyst, indicating higher methanol cracking in the kaolin-based catalyst. The catalyst prepared with bentonite as the binder showed the best performance due to lower methanol cracking, better material balance, and higher conversion efficiency, making it the most suitable option for an atom-efficient catalytic process.
Further, a lower methanol-to-xylenol ratio suggests reduced methanol loss when bentonite is used.
Additionally, a lower methanol-to-DMP ratio can lead to a two-phase product stream. However, maintaining a 1:5:1 ratio of xylenol, methanol, and water ensures that water and xylenol remain in a single, solubilized phase, preventing phase separation. The use of bentonite as a binder effectively suppresses methanol cracking, helping to maintain reaction homogeneity. The table 1 below demonstrates average concentration and average selectivity of the reaction of conversion of 2,3-xylenol to trimethyl phenol using the catalyst composition (composite) as described in example (1a and 1b).
Table 1: Comparison table demonstrating the average concentration and average selectivity of catalyst using various binders.
Binder TOS(h) Average Conv (%) Average Selectivity (%) MeOH/Xylenol ratio
2,3,6-TMP 2,5-XYL 2,4,6- TMP
20% Bentonite 0-28 82.77 95.11 1.19 0.03 2.37
20% Attapulgite 0-28 88.00 93.37 1.76 0.05 2.70
20% Kaolin 0-28 94.05 93.73 0.8 0.06 3.19
10% Cellulose 0-28 93 95 1.1 0.02 2.01
20% Bentonite 0-28* 96.21 94.01 1.01 0.04 2.27
*Beyond 28 hrs time on stream (TOS), improvement in performance with a decrease in methanol consumption is observed.
Gas chromatography (GC) analysis confirmed these results, demonstrating efficient conversion and high selectivity, even though the overall liquid material balance was low (see Figure 1). The chromatogram presented in Figure 1 illustrates the screening of bentonite as a binder, highlighting the high selectivity for 2,3,6-trimethyl phenol (TMP) relative to trace-level byproducts. In conclusion, both cellulose and bentonite as binders in catalyst preparation showed high selectivity for the desired product, 2,3,6-TMP, with minimal formation of undesired by-products like 2,5-DMP.
Example 2: Screening of catalyst with 20% bentonite for extended time (refer figure 2)
An extended run of up to 572 hours of Time on Stream (TOS) was conducted with 4-hour sampling intervals, showing that the reaction mass remained a homogeneous yellowish mixture. The overall liquid material balance was 91%. Over the course of the run, the 2,3-Xylenol conversion decreased from 82% to 70%, while the average selectivity for 2,3,6-TMP remained high at 95%, and 2,5-Xylenol selectivity averaged 2.0%. Other byproducts, including tetramethyl phenol, anisole, 2,4,6-TMP, and traces of other compounds, were also observed. Despite the decrease in conversion with time, the catalyst maintained its selectivity toward 2,3,6-TMP.
In conclusion, the catalyst with 20% bentonite outperformed the 10% cellulose catalyst in extended time-on-stream tests. Despite a gradual decrease in 2,3-Xylenol conversion from 82% to 70%, the bentonite catalyst maintained high selectivity for 2,3,6-TMP (95%) and low byproduct formation. The overall liquid material balance of 91% and the homogeneous reaction mass throughout the run demonstrated its efficiency and stability. The bentonite-supported catalyst showed better durability and sustained performance over long durations, with less mechanical degradation.
Figure 2 specifically illustrates the performance of the catalyst over an extended 572-hour time-on-stream, highlighting its stability and durability. It shows consistent selectivity for 2,3,6-TMP and a gradual decline in 2,3-xylenol conversion, confirming the catalyst’s sustained activity and minimal mechanical degradation over time.
Example 3: Analysis of Crushing strength of catalyst to determine mechanical integrity
Extrudates of catalyst with 20% bentonite, catalyst with 20% cellulose, and catalyst with 10% cellulose respectively with similar shapes of 10-15 mm in length and 3 mm in diameter were chosen for the analysis. A gradual load was applied to each extrudate sample, and the point at which fracture occurred was noted as the crushing strength for the respective extrudate sample. The particle crushing strength of the catalysts, with bentonite and cellulose as binders, was evaluated following the ASTM D 6175 method.
Table 2: Demonstrates the comparison between crushing strength of the samples, expressed in kilogram force (kgf), for various binder compositions: 20% bentonite, 10% cellulose, and a combination of both.
Catalyst with 20% Bentonite Catalyst with 20% Cellulose Catalyst with 10% Cellulose
Average 8.48 0.43 2.03
Range 7.00 – 9.00 kgf 1.00 – 3.00 kgf 1.00 – 3.00 kgf

The data in the above table shows that the 20% bentonite-bound catalyst had a significantly higher crushing strength (8.48 kgf on average) compared to the 20% cellulose-bound catalyst (0.43 kgf on average) and 10% cellulose-bound catalyst (2.03 kgf on average), indicating superior mechanical strength. Bentonite also provides more consistent performance, with a narrow range of crushing strength (7–9 kgf). Thus, while cellulose may have certain advantages, such as biodegradability, bentonite is observed to have importance due to its superior strength and stability while industrial large scale catalyst composition preparation.
[0059] The presently disclosed a composition for production of alkyl phenols may have the following advantageous functionalities over the conventional art:
• High yield and selectivity
• Reduced alkylating agent decomposition
• Optimal conversion efficiency
• Extended catalyst lifespan
• Cost-effective
• Environmental sustainability
• Improved operational simplicity
• Better mechanical integrity
• Longer catalyst life
[0060] The foregoing description shall be interpreted as illustrative and not in any limiting sense. A person of ordinary skill in the art would understand that certain modifications would be encompassed within the scope of this disclosure. The embodiments, examples and alternatives of the preceding paragraphs or the description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.
,CLAIMS:WE CLAIM:
1. A catalyst composition for production of alkyl phenols, comprising:
an active phase present in an amount in the range of 80% - 99 %w/w;
one or more promoters present in the range of 10% - 30 %w/w; and
a binder component present in the range of 5% - 35% w/w of the active phase.
2. The composition as claimed in claim 1, wherein the active phase is iron oxide (Fe2O3).
3. The composition as claimed in claim 1, wherein the one or more promoters L1, L2, and L3 metal oxide promoters selected from silicon oxide (SiO2), chromium oxide (Cr2O3), and potassium oxide (K2O).
4. The composition as claimed in claim 3, wherein the catalyst and promoters such as Fe2O3: L1: L2: L3 is Fe2O3: SiO2:Cr2O3: K2O having a molar ratio ranging between 200:5:1:0.05 to 50:5:1:0.01.
5. The composition as claimed in claim 1, wherein the binder component B is selected from the group consisting of bentonite, attapulgite, and kaolin.
6. The composition as claimed in claim 1, wherein the catalyst, promoters and binder component Fe2O3: SiO2:Cr2O3: K2O: B having a content ratio in the range of 200: 5: 1: 0.05: 20.6 to 50: 5: 1: 0.01: 5.6.
7. The composition as claimed in claim 1, wherein the catalyst composition comprises of auxiliary promoters such as A1 and A2.
8. The composition as claimed in claim 7, wherein A1 is selected from the group consisting of manganese oxide (MnO2), cerium oxide (CeO2), and zirconium oxide (ZrO2), and wherein A2 is selected from the group consisting of zinc oxide (ZnO), magnesium oxide (MgO), and lanthanum oxide (La2O3).

9. The composition as claimed in claim 1, wherein the crushing strength of the catalyst composition is 5-14 kgf.
10. The composition as claimed in claim 1, wherein the catalyst composition produces alkyl phenol by reacting xylenol: methanol: water in a specific feed ratio ranging between 1:2:0.5 to 1:10:2.

Dated this 14th day of May, 2025


ABHIJEET GIDDE
AGENT FOR THE APPLICANT
IN/PA- 4407