Cumene Process Research Articles

Formal Transformation of Benzylic Carboxylic Acids to Phenols.

Phenols play a crucial role as core structural motifs in natural products and also serve as fundamental building blocks in synthetic chemistry. Apart from the known protocols for the conversion of aryl precursors to phenols (i.e., decarboxylative oxygenation), we report here the efficient synthesis of phenols from the stable and readily available benzylic carboxylic acids under mild reaction conditions. The photocatalytic conversion of carboxylic acids to peroxides is a crucial step in this strategy, allowing the subsequent C-O bond formation via Hock rearrangement.

Propane wet reforming over PtSn nanoparticles on γ-Al2O3 for acetone synthesis

Acetone serves as an important solvent and building block for the chemical industry, but the current industrial synthesis of acetone is generally accompanied by the energy-intensive and costly cumene process used for phenol production. Here we propose a sustainable route for acetone synthesis via propane wet reforming at a moderate temperature of 350 oC with the use of platinum-tin nanoparticles supported on γ-aluminium oxide (PtSn/γ-Al2O3) as catalyst. We achieve an acetone productivity of 858.4 μmol/g with a selectivity of 57.8% among all carbon-based products and 99.3% among all liquid products. Detailed spectroscopic and controlled experiments reveal that the acetone is formed through a tandem catalytic process involving propene and isopropanol as intermediates. We also demonstrate facile ketone synthesis via wet reforming with the use of different alkanes (e.g., n-butane, n-pentane, n-hexane, n-heptane, and n-octane) as substrates, proving the wide applicability of this strategy.

Plant Design for the Production of Propylene Oxide by Isopropylbenzene 2-phenylpropane, or (1-Methylethyl) Benzene (Cumene)

Cumene is a colorless, volatile liquid with a gasoline-like odor. It’s also known as isopropylbenzene, 2-phenylpropane, or (1-methylethyl) benzene. It’s a natural component of coal tar and crude oil, and it can also be employed in gasoline as a blending component. Cumene hydroperoxide is produced by oxidizing cumene with benzene and propylene in the presence of air. As a result, the cumene hydroperoxide is changed to cumyl alcohol, which is then transformed to propylene without the use of oxygen. Propylene oxide is an organic compound produced through various methods such as the cumene process and the hydroperoxide process. The cumene method is preferred due to its low by-product production and high market value of co-products. The reactive distillation process is a feasible method for producing propylene oxide with high purity and reduced costs. Future work includes optimizing processes, developing new catalysts, and improving efficiency. Propylene oxide has practical applications in the production of polyurethane foams, coatings, adhesives, polyether polyols, and propylene glycols.

Fuzzy averaging level control for tight product quality control

AbstractThis work develops a fuzzy averaging level controller (ALC) to mitigate flow variability while avoiding high and low level alarm limit breaches. Comparison with proportional (P) and proportional integral (PI) level controllers and their non‐linear variants demonstrates the fuzzy controller to be highly effective in mitigating flow transients for low and moderate size flow disturbances. The performance is comparable for large disturbances. Application of the developed fuzzy ALC to a ternary benzene‐toluene‐xylene direct split separation scheme as well as the separation section of a conventional cumene process demonstrates significantly superior product quality control due to flow transient variability mitigation. The product quality control variability is reduced by up to 1.5 times. The developed fuzzy ALC is therefore suitable for plant‐wide control applications.

Metal-Organic Framework-Supported Mono Bipyridyl-Iron Hydroxyl Catalyst for Selective Benzene Hydroxylation into Phenol.

Direct hydroxylation of benzene to phenol is more appealing in the industry for the economic and environmentally friendly phenol synthesis than the conventional cumene process. We have developed a UiO-metal-organic framework (MOF)-supported mono bipyridyl-Iron(II) hydroxyl catalyst [bpy-UiO-Fe(OH)2] for the selective benzene hydroxylation into phenol using H2O2 as the oxidant. The heterogeneous bpy-UiO-Fe(OH)2 catalyst showed high activity and remarkable phenol selectivity of 99%, giving the phenol mass-specific activity up to 1261 mmolPhOHgFe-1 h-1 at 60 °C. Bpy-UiO-Fe(OH)2 is significantly more active and selective than its homogeneous counterpart, bipyridine-Fe(OH)2. This enhanced catalytic activity of bpy-UiO-Fe(OH)2 over its homogeneous control is attributed to the active site isolation of the bpy-Fe(OH)2 moiety by the solid MOF that prevents intermolecular decomposition. Moreover, the exceptional selectivity of bpy-UiO-Fe(OH)2 in benzene to phenol conversion is originated via shape-selective catalysis, where the confined reaction space within the porous UiO-MOF prevents the formation of larger overoxidized products such as hydroquinone or benzoquinone, leading to the formation of only smaller-sized phenol after monohydroxylation of benzene. Spectroscopic and controlled experiments and theoretical calculations elucidated the reaction pathway, in which the in situ generated •OH radical mediated by bpy-UiO-FeII(OH)2 is the key species for benzene hydroxylation. This work underscores the significance of MOF-supported earth-abundant metal catalysts for sustainable production of fine chemicals.

Dehydration of Isopropanol over Silica-Supported Heteropoly Acids

Dehydration of i-PrOH is used in academic research as a test reaction to probe the acid properties of solid acid catalysts. Also, it has practical importance for the utilization of surplus acetone produced by the Hock process for the combined manufacturing of phenol and acetone as well as for the production of propene from renewable resources and waste. This study demonstrates the excellent performance of polyoxometalate acid catalysts comprising silica-supported Keggin-type heteropoly acids H3PW12O40 and H4SiW12O40 for gas-phase i-PrOH-to-propene dehydration at ambient pressure. These catalysts show similar efficacies, giving an i-PrOH conversion and propene selectivity of 96.8 and 99.7% for 25%HPW/SiO2 and 97.1 and 99.4% for 25%HSiW/SiO2 in a fixed-bed reactor at 120 °C, a relevant-to-practice i-PrOH partial pressure of 15 kPa and a contact time W/F = 27 g h mol−1 (GHSV = 900 mL g−1 h−1). The catalysts are stable, resisting deactivation for at least 24 h time on stream. The HPA/SiO2 catalysts are superior to aluminosilicate zeolites such as H-mordenite, HZSM-5 and HY for i-PrOH-to-propene dehydration in terms of i-PrOH conversion, propene selectivity and catalyst stability.

Internal model control of cumene process using analytical rules and evolutionary computation

Cumene is a precursor for producing many organic chemicals and is thinner in paints and lacquers. Its production process involves one of the large-scale manufacturing processes with complex kinetics. Different classical control strategies have been implemented and compared in this process for the cumene reactor. As a system with large degrees of freedom, a novel approach for extracting the state space model from the COMSOL Multiphysics implementation of the system is adopted here. Internal Modern Control (IMC) based PI and PID controllers are derived for the system. The system is reduced to the FOPDT and SOPDT model structure to derive the controller setting using Skogestad half rules. The integral time is modified for excellent set point tracking and faster disturbance rejection. From the analysis, it can be stated that the PI controller suits more for this specific process. The particle swarm optimization (PSO) algorithm, an evolutionary computation technique, is also used to tune the PI settings. The PI controllers with IMC, Zeigler Nichols, and PSO tuning are compared, and it can be concluded that the PSO PI controller settles at 45 s without any oscillations and settles down faster for the disturbance of magnitude 0.5 applied at t = 800 s. However, it is computationally intensive compared to other controller strategies.

Multiobjective particles swarm optimization and multicriteria decision making of improved cumene production process including economic, environmental, and safety criteria

AbstractCumene is one of the five chemicals with the highest production in the world. In this work, the design by Flegiel was improved to increase the production rate of the cumene process by adding a trans‐alkylation reactor, then multi‐objective optimization (MOO) using the particles swarm optimization (PSO) algorithm is used to improve the process design. Furthermore, seven multicriteria decision‐making (MCDM) methods for selecting an optimal solution from the Pareto‐optimal front related to two MOO problems were performed. In this optimization, conflicting objectives such as total capital cost (TCC), energy cost, wastage rate, and safety target are simultaneously minimized in the format of trade‐offs. Finally, the results of this work were compared with those reported designs. The optimal solution chosen by MCDM methods is at TCC = 5589, damage index (DI) = 0.044, and material loss = 0.0005.

Comparative Analysis of Bio- and Chemo-Catalysts for the Synthesis of Flavour Compound Hexanal from Linoleic Acid

Hexanal, hexenal, nonenal and their corresponding alcohols are used as green notes in the fragrance and flavour industry. The production of bio-based hexanal starts from linoleic acid, which can be obtained from sunflower or safflower oil. The biocatalytic process utilizes C13-specific lipoxygenase (LOX) for hydroperoxidation and consecutive splitting with hydroperoxide lyase (HPL). In this study, we investigated the chemical splitting of the LOX product 13-HPODE in comparison to HPL catalysis. In addition, 13-HPODE was synthesized using enriched linoleic acid from safflower oil. Varying amounts of soybean flour suspension as a source of LOX yielded up to 60% HPODE with a regioselectivity of 92% towards 13-HPODE. Using low-toxicity Lewis acids like AlCl3 and ZrCl4, cleavage of the produced 13-HPODE was possible. A maximum hexanal yield of 22.9% was reached with AlCl3 under mild reaction conditions, though product degradation was an interfering process. Comparative trials with N-terminal truncated HPL from papaya revealed hexanal recovery within a comparable range. Additionally, we successfully demonstrated the viability of Hock rearrangement of 13-HPODE through heterogeneous catalysts. Notably, Beta zeolite and Montmorillonite K10 exhibited a turnover frequency (TOF) on par with common heterogeneous catalysts employed in industrial processes.

Theoretical Investigation of the Mechanism of the Hock Rearrangement with InCl3 as Catalyst**

AbstractThe Hock rearrangement is an acid catalyzed reaction involving organic hydroperoxides and resulting in an oxidative cleavage of adjacent C−C bonds. It has significant industrial applications, like the production of phenol (cumene process), but it remains scarcely used in organic synthesis. In addition, its detailed mechanism has never been studied. Thus, we report herein a theoretical study of the Hock rearrangement, using InCl3 as a Lewis acid catalyst. The aim of this work was to fully understand the mechanism of this fundamental reaction, and to rationalize the influence of the substrate electronic properties on the reaction outcome. Furthermore, the structure of the active indium(III) catalyst interacting with the peroxide substrate was investigated, revealing the co‐existence of several energetically close reaction pathways. The coordinated monomeric form of the Lewis acid emerges as the most active catalyst compared to dimeric species. However, we show that In2Cl6 species coordinated to the substrate are central in this catalytic cycle, primarily serving as a reservoir of active monomeric species.

Direct Synthesis of Acetone by Aerobic Propane Oxidation Promoted by Photoactive Iron(III) Chloride under Mild Conditions

C–H activation of hydrocarbons is extremely challenging, especially in short-chain hydrocarbons like propane. In industry, propane is first converted to propylene mostly by steam cracking, which is only oxidized to acetone in the cumene process, yielding acetone and phenol. In this work, we show that the simple FeCl3 salt in acetonitrile photocatalyzes the oxidation of propane to acetone at room temperature under aerobic conditions and visible-light irradiation. We achieved 100% conversion of propane with 67% selectivity in acetone after 4 h of irradiation and TON up to 600. Mechanistic studies, including electrospray ionization mass spectrometry, Mössbauer, and electroparamagnetic resonance spectroscopy, concluded that the reaction is driven by chlorine radicals generated by Fe–Cl bond photolysis. These results not only hold promise for the development of solar-based oxidation of hydrocarbons but more importantly also disclose deeper insights into the largely overlooked photochemistry of FeCl3.

High-Temperature-Treated LTX Zeolites as Heterogeneous Catalysts for the Hock Cleavage

Hydroxybenzene, commonly known as phenol, is one of the most important organic commodity chemicals. To produce phenol, the cumene process is the most used process worldwide. A crucial step in this process is the Hock rearrangement, which has a major impact on the overall cumene consumption rate and determines the safety level of the process. The most used catalyst for the cleavage of cumene hydroperoxide (CHP) is sulfuric acid. Besides its strong corrosive property, which increases plant investment costs, it also requires neutralization after the decomposition step to prevent side reactions. In this study, we show that high-temperature-treated Linde Type X (LTX) zeolites exhibit a high activity for the peroxide cleavage step. In addition, the structure–activity relationship responsible for this good performance in the reaction system of the HOCK rearrangement was investigated. XRPD analyses revealed the formation of a new phase after temperature treatment above 900 °C. The Si/Al ratio determined by EDX suggested the formation of extra-framework aluminum, which was confirmed by solid-state NMR analysis. The newly formed extra-framework aluminum was found to be responsible for the high catalytic activity. BET analyses showed that the surface area drops at higher calcination temperatures. This leads to a lower catalytic activity for most known reactions. However, for this study, no decrease in activity has been observed. The newfound material shows extraordinarily high activity as a catalyst in the HOCK cleavage and has the potential to be a heterogeneous alternative to sulfuric acid for this reaction.

Utilization of Acetone, By-Product of Cumene Process for Phenol Production, via BaSnO3-Catalyzed Aldol Condensation

Utilization of Acetone, By-Product of Cumene Process for Phenol Production, via BaSnO3-Catalyzed Aldol Condensation

Highly Dispersed Vanadia Anchored on Protonated g-C3N4 as an Efficient and Selective Catalyst for the Hydroxylation of Benzene into Phenol

The direct hydroxylation of benzene is a green and economical-efficient alternative to the existing cumene process for phenol production. However, the undesired phenol selectivity at high benzene conversion hinders its wide application. Here, we develop a one-pot synthesis of protonated g-C3N4 supporting vanadia catalysts (V-pg-C3N4) for the efficient and selective hydroxylation of benzene. Characterizations suggest that protonating g-C3N4 in diluted HCl can boost the generation of amino groups (NH/NH2) without changing the bulk structure. The content of surface amino groups, which determines the dispersion of vanadia, can be easily regulated by the amount of HCl added in the preparation. Increasing the content of surface amino groups benefits the dispersion of vanadia, which eventually leads to improved H2O2 activation and benzene hydroxylation. The optimal catalyst, V-pg-C3N4-0.46, achieves 60% benzene conversion and 99.7% phenol selectivity at 60 oC with H2O2 as the oxidant.

Recent Advances in the Heterogeneous Photocatalytic Hydroxylation of Benzene to Phenol.

Phenol is an important chemical material that is widely used in industry. Currently, phenol is dominantly produced by the well-known three-step cumene process, which suffers from severe drawbacks. Therefore, developing a green, sustainable, and economical strategy for the production of phenol directly from benzene is urgently needed. In recent years, the photocatalytic hydroxylation of benzene to phenol, which is economically feasible and could be performed under mild conditions, has attracted more attention, and development of highly efficient photocatalyst would be a key issue in this field. In this review, we systematically introduce the recent achievements of photocatalytic hydroxylation of benzene to phenol from 2015 to mid-2022, and various heterogeneous photocatalysts are comprehensively reviewed, including semiconductors, polyoxometalates (POMs), graphitic carbon nitride (g-C3N4), metal–organic frameworks (MOFs), carbon materials, and some other types of photocatalysts. Much effort is focused on the physical and chemical approaches for modification of these photocatalysts. The challenges and future promising directions for further enhancing the catalytic performances in photocatalytic hydroxylation of benzene are discussed in the end.

Cumene autooxidation to cumene hydroperoxide based on a gas-liquid microdispersion strategy

Three-step Hock process is widely used in phenol industry, which suffers slow reaction speed, low efficiency, and generation of many by-products. As a key step, cumene oxidation has a significant influence on the quality of produced phenol and the process is controlled by mass transfer. Herein, aimed at enhancing cumene oxidation, microfluidics was used to strengthen the non-catalytic process. Experimental investigation with different microfluidic strategies confirmed that continuous mass transfer enhancement was of great importance for this system. When oxygen was used as the oxidant and operation at 130 °C and 0.8 MPa for 2 h, 66.2% conversion, 92.0% selectivity, and 60.9% yield were obtained, which were better than those in traditional batch reactors. The conversion was doubled while still maintaining a high selectivity of over 90%, and the reaction time was shortened to 1/4 of the original time. On the basis of the enhanced mass transfer, the kinetics of cumene oxidation was also investigated. The obtained reaction order of cumene was approximately 1.5.

Solid Acid Catalysts for the Hock Cleavage of Hydroperoxides

The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol. In this mini-review, first a brief introduction and overview on the Hock process is given. Next, the mechanism, kinetics, and safety aspects are summarized and discussed. Following, the different types of heterogeneous catalysts and their performance as catalyst in the Hock process are illustrated. Finally, the different approaches to substitute sulfuric acid in the synthetic route to produce phenol are briefly concluded and a short outlook is given.

Annulative π-Extension (APEX) of Indoles to Pyrido[1,2-a]indoles Using 4-Oxo Peroxides as C4 Units.

Annulative π-extension (APEX) of 3-substituted indoles to pyrido[1,2-a]indoles is developed by using 4-oxo peroxides as π-extending reagents, which are employed as versatile C4 building blocks. This transformation is initiated by Brønsted acid-mediated Hock rearrangement of the peroxyl group. Notably, the pyrido[1,2-a]indole products are obtained by elimination of the indole moiety from the corresponding dihydropyrido[1,2-a]indoles, which could be selectively formed at room temperature.

Enhanced Room-Temperature Catalytic Decomposition of Cumene Hydroperoxide into Phenol and Acetone

ABSTRACTPhenol is an important industrial chemical that was manufactured by the Hock process. The sulphuric acid used in the Hock process to break cumene hydroperoxide into phenol and acetone suffers from environmental problems along with low selectivity towards the desired products. There are several solid acid catalysts have been tried in cumene hydroperoxide decomposition into an ecofriendly process. In the present work, an efficient environmentally friendly and economically benefitted zeolite-based catalyst was synthesized and tested for breaking cumene hydroperoxide (CHPO) into phenol and acetone. Beta zeolite and ZSM-5 zeolite were synthesised with nano crystalline geometry by hydrothermal method and tested their efficiency to break CHPO. The morphology and structure of nanocrystalline zeolite materials was investigated by Dynamic Light Scattering (DLS), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) methods. From DLS studies it is documented that the zeolite particle size is tuneable as evidenced from particle size growths with the ageing time under hydrothermal treatment process. XRD analysis confirms the zeolite Beta and ZSM-5. The mean crystal size of Beta and ZSM-5 obtained from SEM analysis are 45 nm and 18.3 nm respectively. The optimization of reaction conditions for CHPO decomposition such as catalyst quantity and initial concentration of CHPO has been done using nanocrystalline Beta catalyst. The optimum catalyst amount and concentration of CHPO are 0.03 g and 15 mmol respectively. The results showed that the nanocrystalline Beta zeolite catalyst exhibits exceptional activity with 100% conversion of CHPO and yielded exclusively phenol and acetone at room temperature. No other by-products are detected. Also, the catalyst is stable and exhibits high product selectivity for phenol and acetone. The nature of the enhanced activity at room temperature for the decomposition of CHPO is suggested that higher accessibility of the active sites that are proposed to be associated with the zeolite with nano configuration with higher surface area and short distances for diffusion inside the channels in the nanocrystalline zeolite particles. The possibility of commercialization of beta zeolite is proved by complete conversion of CHPO with selective formation of phenol and acetone.

A Review on Selective Production of Acetophenone from Oxidation of Ethylbenzene over Heterogeneous Catalysts in a Decade

The consumption of acetophenone (AP) is increasing worldwide because of its applications in products such as alcohol, aldehydes, resins, esters, fragrances, and pharmaceuticals. AP is manufactured via several methods like decomposition of cumene hydroperoxide, Hock process, and Friedel–Crafts acylation reaction using homogeneous catalysts with solvent and oxidant. However, it causes several environmental problems that deteriorate the production of AP with these methods. Oxidation of ethylbenzene (EB) is one of the promising methods to synthesize AP in liquid and vapor phases reaction using heterogeneous catalysts, which plays a vital role for selective production of AP. In this review, numerous heterogeneous catalysts are discussed including transition metal nanoparticles, transition metal complexes, and metal free catalysts (carbon nanotubes) used in last 10 years for oxidation of EB. Additionally, catalyst activity along with reaction parameters and its effect, mechanisms, and kinetics study are summarized in this article. The future scope of this reaction is also highlighted. Moreover, this work identifies best catalysts for bulk production of AP with high yield to satisfy global requirement.