Cumene Research Articles

Novel bis(aminoalcohol)oxalamide organogelators and their diglycolylamide analogs: evaluation of gelation efficiency in various organic fluids

Three modular types of bis(aminoalcohol)oxalamides (1,4, and 7) and bis(aminoalcohol)diglycolylamide (8) gelators have been prepared by the reaction of the respective aminoalcohols with oxalyl and digycolyl methylesters as potential low-molecular-weight organogelators. The gelation properties of these amides have been evaluated in various aromatic organic solvents (xylene, toluene, isopropyl benzene, and aromatic ether type organic fluids such as anisole or $\alpha $-phenylethylmethylether) as well as the long-chain aliphatic alcohols (1-hexanol, 1-octanol, 2-octanol, and aromatic 1-phenylethanol). The compounds with \textit{sec}-butyl and ethyl side chains produce good gelation properties in both aromatic and other organic fluids. Furthermore, the common oxalamide linker present in the gelators was replaced by an extended diglycolylamide linker (8) and its behaviors were compared with the benzylic oxalamide analog (3). The gelator (8) gives the best results with aromatic fluid and lauric acid ethyl ester. $^{1}$H NMR studies reveal the existence of temperature-dependent network assembly/dissolution equilibrium and produce $K_{gel}$. FTIR was employed to see the effect of hydrogen bonding in the formation of gel network. Thermodynamic parameters regarding gel-to-sol transition were collected with van't Hoff relationships. K_${gel}

Superior heat-resistant and oil-resistant blends based on dynamically vulcanized hydrogenated acrylonitrile butadiene rubber and polyamide 12

High-performance thermoplastic vulcanizates (TPVs) are the new generation of TPVs that provide superior heat and oil aging behavior. TPVs based on hydrogenated acrylonitrile butadiene rubber and polyamide 12 (PA12) have been first developed by the dynamic vulcanization process, in which selective cross-linking of the elastomer phase during melt mixing with the thermoplastic phase (PA12) was carried out simultaneously. In this present investigation, hydrogenated acrylonitrile butadiene rubber (HNBR)/PA12 and partially hydrogenated carboxylated acrylonitrile butadiene rubber (XHNBR)/PA12 with blend ratio of 50:50, 60:40, and 70:30 wt% were prepared at 185°C at a rotor speed of 80 rpm for 5 min. Di-(2-tert-butyl peroxy isopropyl) benzene was chosen as the suitable cross-linking peroxide to pursue the dynamic vulcanization. TPV based on 50:50 HNBR/PA12 and XHNBR/PA12 show better physico-mechanical properties, rheological behavior, thermal stability, dynamic mechanical analysis, and creep behavior among all the TPVs. Morphology study reveals that dispersed phase morphology has been formed with an average dimension of the rubber particles in the range of 0.8–1.5 µm. For aging test, TPVs were exposed to air and ASTM oil 3, respectively. Air aging tests were carried out in hot air oven for 72 hr at 125°C, while the oil aging tests were carried out after immersion of the samples into the oils in an aging oven. After aging, there is only slight deterioration in the physico-mechanical properties of the TPVs. In case of 50:50 blends of HNBR/PA12 and XHNBR/PA12, the retention of the properties upon after aging was found excellent. These TPVs are designed to find potential application in automotive sector especially for under-hood-application, where high-temperature resistance as well as high oil resistance is of prime importance. Copyright © 2016 John Wiley & Sons, Ltd.

Asphaltene solubility in common solvents: A molecular dynamics simulation study

AbstractSolubility of all proposed molecular models of asphaltene in various solvents is studied through molecular dynamics simulation to find the structural parameters which have a determining effect on asphaltene solubility. It is found that higher numbers of aromatic rings and heteroatoms such as oxygen, nitrogen, and sulphur in the molecular structure of asphaltenes raises their solubility in the solvents, whereas the length of aliphatic group, which increases the chain length, lowers their solubility. In addition, a cubic correlation equation for evaluating the asphaltene solubility parameter as a ratio of number of aromatic rings in the asphaltene molecular core to the number of carbon atoms in the asphaltene side chains is proposed. The results indicate that the relative energy difference (RED) of asphaltene models and isopropyl benzene, as a solvent, is the lowest compared with other solvents. To elucidate the mechanism of asphaltene dissolution in the common solvents the solubility of two asphaltene structural models in three solvents, including isopropyl benzene, toluene, and heptane, were studied by evaluating the radial distribution functions (RDFs) of the asphaltenes, and the results confirm that asphaltene has the highest solubility in isopropyl benzene.

Upgrading of Waste Tyre-Derived Oil from Waste Tyre Pyrolysis over Ni Catalyst Supported on HZSM-5 Zeolite

The catalytic pyrolysis of waste tyre was investigated using Ni-doped HZSM-5 zeolite as a catalyst in a bench-scale reactor ramped from room temperature to 500 °C (pyrolysis zone) and 350 °C (catalyst bed), aiming to improve the quality of tyre-derived oil in terms of sulphur reduction and enhancement of valuable petrochemical production. 5 wt% of nickel was introduced on HZSM-5 zeolite using incipient wetness impregnation, and characterised using XRD, surface area analyser, and XPS. Gaseous products were analysed by GC-FID. The GCxGC-TOF/MS and SIMDIST-GC were used for analysis of pyrolysis oil. The sulphur content in tyre-derived oil was determined by S-analyser. The introduction of metallic nickel on HZSM-5 zeolite significantly changed textural properties, also modified the catalytic behaviour. When compared to parent HZSM-5 zeolite, Ni/HZSM-5 catalyst significantly improved gasoline and kerosene production in waste tyre-derived oil, whereas the heavy fractions, such as gas oil and light vacuum gas oil, drastically decreased. In addition, Ni doping drastically reduced sulphur contents in tyre-derived oil by 29.2%. Benzothoiphenes, dibenzothiophenes, and naphthothiophene were the sulphur species that significantly decreased. Furthermore, with Ni loading, the production of cumene, ethylbenzene, toluene, and mixed xylenes in oil was also enhanced. These results indicated Ni/HZSM-5 was a promising catalyst for enhancement of tyre-derived oil quality.

Pulse radiolysis investigation of · OH and · H radicals initiated degradation reaction of sulfonated aromatics as model compounds for proton exchange membrane

In order to predict ·OH and ·H radicals initiated degradation of proton exchange membrane (PEM) based on polymers obtained by radiation-induced grafting of styrene or α-methylstyrene on different polyolefin, isopropyl benzene sulfonic acid (IPBS) and tert-butyl benzene sulfonic acid (TBBS) were taken as model compounds for PEM with and without α-H, respectively. Results indicated that ·OH radicals played a vital role in PEM degradation. Eighty-nine percent of ·OH radicals reacted with IPBS to form benzylic radicals by electron transfer and subsequent deprotonation reactions. Benzylic radicals can react with O2 to form peroxyl radicals, which leads to PEM degradation. TBBS, without α-H, reacted with ·OH or ·H radicals, benzylic radicals would not be generated, and only adducts were formed. Adducts have less influence on the stability of TBBS than benzylic radicals. In this work, we elucidated that PEM, without α-H, with similar structures to TBBS, had a stronger resistance to oxidative degradation than PEM with α-H, with similar structures to IPBS.

Aerobic Oxidation of 2‑isopropyl‑1,4‑dimethylbenzene to tertiary hydroperoxide

Abstract: The regularities of aerobic oxidation of isopropyl-para-xylene to tertiary hydroperoxide in the environment of standard industrial initiators, as well as N-hydroxyphthalimide as catalyst are studied. A mechanism of liquid-phase catalyzed oxidation of isopropyl-para-xylene is discussed. Keywords: oxidation, 2,5-xylenol, hydroperoxide, N‑ hydroxyphthalimide. Introduction Liquid-phase oxidation of alkylaromatic hydrocarbons forms the basis for promising methods of obtaining various oxygen compounds — (alkyl)phenols and aliphatic ketones, which are widely used in synthesis of polymeric substances with a range of useful properties.The “cumene” method of phenol and acetone production and the styrene and propylene oxide co-synthesis (Halcon process) have been thoroughly researched and are widely used in industry. The key stage in these processes is the liquid-phase initiated oxidation of isopropylbenzene (IPB) or ethylbenzene to respective hydroperoxides (HP) [1, 2].This important direction of organic synthesis can be broadened by using other alkylaromatic hydrocarbons and their HPs.This paper discusses the study of liquid-phase selective oxidation of 2- -isopropyl1,4dimethylbenzene (IPX) to tertiary HP, which -forms the basis of synthesis of 2,5xylenol, a -large volume oil synthesis product, which is applied in production of vitamin E, plasticizers, paint and coatings, and disinfectants, according to the scheme:

Static Simulation of Heat Exchanger Circuit of Cumene Production

Bir isi degistiricisi, iki veya daha fazla sivi arasindaki, kati veya sivi arasindaki veya kati parcaciklar ve akiskan arasindaki termal ic enerjisini disaridan isi ve is girisi olmaksizin gerceklestiren cihazlardir. Isi degistiricileri kullanim amaclarina gore degisik konstruksiyonlarda, kapasitelerde, boyutlarda ve tiplerde olabilmektedirler. Isi geri kazanim amacli kullanilan isi degistiricileri sanayi kuruluslarinda yatirim maliyetinde onemli bir yer tutmaktadir. Bu nedenle isi degistiricisi secilirken veya isi degistiricisi devreleri tasarlanirken oldukca dikkat edilmeli ve isi geri kazaniminin maksimum olmasi icin dogru isi degistiricisi veya efektif bir isi degistiricisi devresi tasarlanmasi gerekmektedir. Bu calismada, bir kumen uretim tesisinde bulunan isi degistiricisi devresinin statik simulasyonu yapilmistir. Devreye giris yapan ve devreden cikis yapan sicak ve soguk akislarin koordinatlari matris denklemleriyle tanimlanarak devre icerisindeki sicaklik dagilimlari ve devre cikisindaki sicakliklar iterasyona basvurulmadan, ozel yazilim ve donanimlara basvurmaksizin yuksek bir dogrulukta elde edilmistir. Simulasyon sonucunda isi degistiricisi devresindeki her bir hucreden gecen sicak akis ve soguk akisa ait sicakliklar isletme sartlari ile ortusecek sekilde tam dogrulukta elde edilmistir. Ayrica devre icerisindeki isi degistiricilerindeki sicaklik dagilimlari elde edilerek devrenin statik durumunun izlenmesi saglanmistir.

Preparation and chromatic properties of C@ZrSiO4 inclusion pigment via non-hydrolytic sol–gel method

A zirconium silicate coated carbon (C@ZrSiO4) black pigment was prepared via a non-hydrolytic sol–gel (NHSG) process. Phenolic resin was carbonized at high temperature in N2 atmosphere and dense ZrSiO4 was coated on its surface to prevent it to be oxidized for the glaze application. The structure and morphology of samples were studied by using X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The chromatic value of the pigments was characterized by the CIE color system. XRD results reveal that the ZrSiO4 phase can be obtained at 650 °C and degree of crystallinity increases with increasing the calcination temperature. The darkness of the samples prepared by different solvents was decrease in sequence of isopropyl alcohol, alcohol and benzene, which is consistent with their solubility to phenolic resin. After calcining at 900 °C for 2 h, the small in-situ carbon was tightly coated by zirconium silicate to form the inclusion pigment. This pigment exhibits excellent chromatic value (L* = 42.01) and good stability in transparent glaze, which indicates it is a potential candidate for ceramic pigments application.

Modeling of shock wave initiation of an explosion of individual bubbles in liquid hydrocarbon fuels

A physicomathematical model of shock wave initiation of an explosion of oxygen-containing bubbles in liquid hydrocarbon fuels is developed. The model is used to calculate an explosion of bubbles in which the initial concentration of fuel vapors is outside the flammability limits. A principal possibility of condensation of fuel vapors during compression of a fuel-rich bubble located in liquid cyclohexane with a comparatively high initial temperature is demonstrated. Condensation leads to a decrease in the fuel concentration in the gas lower than the fuel-rich flammability limit. As a result, an explosion of an initially non-combustible bubble becomes possible. The condensation rate is estimated. It is found to be sufficiently high to change the chemical composition of the gas during the period of the first oscillation of the bubble. The explosion limits of the bubble are calculated as functions of the initial pressure, temperature, and amplitude of the shock wave. If condensation is taken into account, the explosion limits are expanded. Bubble liquids (2-ethylhexanol and isopropyl benzene) where the fuel vapor concentration is initially lower than the fuel-lean flammability limit are considered. It is shown that liquid evaporation induced by mechanical mixing of the phases can shift the chemical composition of the gas inward the flammability region, resulting in a bubble explosion with a corresponding increase in gas temperature. Calculated and experimental results are found to be in good agreement. Explosive processes in bubble media containing a liquid monopropellant are considered at the qualitative level for the first time. An assumption is put forward about a possibility of multiple explosions of an individual bubble loaded by a series of shock waves and subjected to multiple transitions of the detonation wave over the liquid with distributed bubbles, which may be used for generating a series of powerful acoustic signals in the ambient space.

Structure and dynamics of cumene and 1,2,4-trimethylbenzene mixture in NaY zeolite: a molecular dynamics simulation study

A molecular dynamics study of 1:1 mixture of the C9 isomers, isopropyl benzene (cumene) and 1,2,4-trimethylbenzene (124TMB) (pseudocumene), in zeolite NaY is reported. Structural and dynamical properties have been computed to understand possible difficulties in the separation of these isomers. Cumene exhibits a slightly higher self-diffusivity. 124TMB encounters a larger barrier as compared with cumene at the 12-ring window during migration from one supercage to another. 124TMB has a significantly larger backscattering during rotation which may be attributed to its shape and large cross-sectional diameter as compared with cumene. Cumene has a higher rotational diffusivity. Results suggest that there is larger difference between the rotational diffusivities of the two isomers and little difference in their translational diffusivity. It may be possible to exploit this difference in separating the two isomers.

Simulation and Process Integration of Clean Acetone Plant

Acetone is produced worldwide by cumene hydroperoxide process. Alternatively, free of aromatic compounds acetone is obtained by isopropyl alcohol (IPA) dehydrogenation. The feedstock is azeotropic mixture IPA-water (Luyben, 2011). This contribution aims to evaluate process feasibility both in terms of reaction engineering and separation by distillation. Rational use of energy is based on process integration A process flowsheet with better performance is proposed. The dehydrogenation reaction is endothermic with number of moles increase. Higher temperature and decreased IPA partial pressure using inert (water) are favourable. Reaction kinetics in vapour phase is simulated in Aspen HYSYS ® with LangmuirHinshelwood-Hougen-Watson (LHHW) model, considering both direct reaction and reverse reaction terms, based on experimental data (Lokras, 1970). Such more realistic model is not considered in other papers (Luyben, 2011). The chemical reactor is simulated as an ideal CSTR. High volatile and non-condensable compounds from the cooled reactor effluent are separated into a flash unit. To minimize the loss of acetone in gas stream, an absorption column with water is considered. Possible separation schemes for liquid effluent (consisting of acetone, IPA and water) are evaluated with residual curves maps (RCM) built in SIMULIS ® ver.1.3. This system has IPA-water azeotrope, a saddle node. The boundary, separes two distillation regions. Both direct and reverse separation schemes are possible. Two distillation columns are used to separate the components of flash unit bottom stream product and absorbtion column bottom stream product. As designed by RCM, for direct scheme, acetone separates in first column top product, and IPA-water azeotropic mixture separates as second column top product. This is recycled to meet plant feedstock stream. Water separated as second column bottom stream product is partly recycled, after cooling, to the absorption column. To minimise utilities consumption and to synthesize process heat exchangers network (HEN), maximum energy recovery (MER) methodology is used with SPRINT © software. The proposed HEN is included in process flowsheet. Energy saving is 35 % for hot utilities and 37 % for cold utilities, compared to non-integrated scheme.

Saturation recovery electron spin–lattice relaxation studies on benzene anion radical and its derivatives: application of Kivelson–Orbach mechanism of electron spin relaxation

The role of low-lying excited states on the spin–lattice relaxation times (T1) of organic radicals has been investigated. To test the applicability of Kivelson's electric field fluctuation model (D. Kivelson, J. Chem. Phys. 45, 1324 (1966)), based on the Orbach mechanism of spin relaxation, the T1s of the anion radicals of benzene, benzene-1-d, toluene, ethyl benzene, isopropyl benzene, t-butyl benzene, p-xylene, 1,2,4-trimethyl benzene and 1,3,5-trimethyl benzene in liquid solutions, with potassium cation as the counter ion, have been measured by the pulse saturation recovery technique. The energy gap between the ground and the first excited electronic states changed with the substitutions to different extent. The spin–lattice relaxation rates showed correlation with this energy gap. Anion radicals of benzene and benzene-1-d showed the shortest T1 among the radicals studied here. A small but measurable energy splitting due to the deuterium substitution in benzene-1-d radical was obtained from the temperature dependence of T1. Spin–lattice relaxation times of benzene anion measured here decreased monotonically in the range of −60 to −125 °C, in contrast to some reported claims of very unusual temperature dependence, based on the continuous wave microwave power saturation studies. Our results also showed that the ion pairing between benzene anion and potassium cation did not significantly influence the spin–lattice relaxation times.

Is it possible to implement N‐hydroxyphthalimide homogeneous catalysis for industrial applications? A case study of cumene aerobic oxidation

AbstractBACKGROUNDIn spite of its efficiency and versatility, examples of the use ofN‐hydroxyphthalimide (NHPI) as catalyst for oxidations at industrial scale are scant, mainly due to the lack of methodologies for the recovery and reuse of the catalyst. This paper reports a step by step investigation of the aerobic oxidation of cumene (CU), in order to verify the usability of NHPI catalysis in industrial processes.RESULTSCU is oxidized to the corresponding cumyl hydroperoxide (CHP) at 70°C in the presence of a polar co‐solvent and 1% of NHPI with good conversion (>30%) and almost complete selectivity (>90%), without requiring the use of additional initiators. The catalyst is recovered at the end of the oxidation process by removal of polar co‐solvent, with consequent precipitation of NHPI. The resulting filtered mixture is treated with non‐basic supports, which are capable of adsorbing the residual NHPI by physical interaction. Finally, the adsorbing solids can be regenerated by washing with a polar solvent, allowing the recovery of residual catalyst.CONCLUSIONWe provide evidence for the feasibility of the use of NHPI catalysis for industrial applications by investigating the case study of CU oxidation. The process can be performed under mild conditions without requiring the use of sacrificial initiators. The effect of temperature and composition in the NHPI precipitation step is investigated. The performances of basic and non‐basic adsorbing beds during the recovery of residual NHPI are compared. The results obtained indicate that the recovery and recycling of the unaltered catalyst is possible without affecting, at the same time, the nature of cumyl hydroperoxide. © 2013 Society of Chemical Industry

Synthesis and characterization of hierarchical titania-silica monolith

Titania-silica monoliths with bicontinuous macropores and ordered mesopores were successfully prepared by a double-template technique. The influence of reactants on pore structures and Ti content was studied in detail. The results demonstrated that acid concentration in starting compositions has a great effect on morphologies of the final samples. Besides, it is also found that the changing of water-soluble organic polymers amount and triblock copolymers amount could adjust the pore size of macropores and the order degree of mesopores respectively. Moreover, the addition of fluoride benefits much more titanium atoms incorporate into the framework of silica. Compared with Ti-SBA-15, the hierarchical titania-silica monolith showed better performance on catalytic reaction of large molecules such as epoxidation of cyclohexene to cyclohexene oxide with isopropyl benzene hydroperoxide.

Controlling PCBM aggregation in P3HT/PCBM film by a selective solvent vapor annealing

A selective solvent vapor, i.e., cyclohexanone or isopropyl benzene, which is a poor solvent for poly(3-hexylthiophene-2,5-diyl) (P3HT) and a good solvent for fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), was employed to reduce the size of PCBM aggregates and prolong the formation time of big PCBM aggregates in P3HT/PCBM film. PCBM nucleates and aggregates of 10-20 nm scale form in the first few minutes annealing. Then the size of PCBM aggregates kept unchanged until annealing for 60 min. Finally, larger PCBM aggregates of micron-size formed hours later. On the contrary, the growth rate of PCBM aggregates was faster and their size was larger when treated with a good solvent vapor for both components. The P3HT crystallinity was the same with different types of annealing solvents, although the rate of P3HT self-organization was decreased after a selective solvent vapor annealing. Because of the smaller size of phase separation, the device annealed in a selective solvent vapor for 30 min had a higher PCE than that annealed in a good solvent vapor.

Functionalization of copolymers of ethylene and vinyl acetate by grafting of trans-ethylene-1,2-dicarboxylic acid in the course of reactive extrusion

Free-radical grafting of trans-ethylene-1,2-dicarboxylic acid to macromolecules of a copolymer of ethylene with vinyl acetate in melt in an extrusion reactor, initiated by 1,3-bis(tert-butyl peroxy isopropyl)benzene, and the structure and mechanical properties of the functionalized products were studied.

Study of the Structure and Parameters of Grid of Hydrogenated Butadiene Nitrile Rubber crosslinked with Polymer Peroxides

Studied the ro le of poly mer pero xide (1,4-b is -tret butyl pero xy isopropyl benzene) and triazine co mpounds (2-phenyl-4, 6-bis -trichloro methyl sym triazine) in hydrogenated butadiene nitrile rubber (HBNR) systems HBNR + Poly meric Pero xide, HBNR + Triazine Co mpounds under heating. By physical and chemical, spectral methods of analysis shown, that the changes in molecu lar structure of HBNR in the presence of poly mer pero xides and triazine co mpounds. Determined the kinetics of yield and the emergence of cross-linking density of the grid HBNR fo r each reaserched system depend on time. It is shown that cross linking of the HBNR with pero xide poly mers occurs by a radical type.

Calorimetric studies and lessons on fires and explosions of a chemical plant producing CHP and DCPO

Cumene hydroperoxide (CHP) has been used in producing phenol, dicumyl peroxide (DCPO) and as an initiator for synthesizing acrylonitrile–butadiene–styrene (ABS) resin by copolymerization in Taiwan. Four incidents of fire and explosion induced by thermal runaway reactions were occurred in a same plant producing CHP, DCPO and bis-(tert-butylperoxy isopropyl) benzene peroxide (BIBP). The fourth fire and explosion occurred in the CHP reactor that resulted in a catastrophic damage in reaction region and even spread throughout storage area. Descriptions on the occurrences of these incidents were assessed by the features of processes, reaction schemes and unexpected side reactions. Calorimetric data on thermokinetics and pressure were used for explaining the practical consequences or which the worst cases encountered in this kind of plant. Acceptable risk associated with emergency relief system design is vital for a plant producing organic peroxide. These basic data for designing an inherently safer plant can be conducted from adiabatic calorimetry. An encouraging deduction has been drawn here, these incidents may be avoided by the implementation of API RP 520, API RP 521, DIERS technology, OSHA 1910.119 and AIChE's CCPS recommended PSM elements.

The Surface Tension of a Mixture System of Acetophenone + Isopropyl Benzene + Phenol at 283.15 K

Surface tensions and densities of binary (acetophenone + isopropyl benzene) and ternary (acetophenone + isopropyl benzene + phenol) mixtures were measured at 283.15 K and normal atmosphere using a platinum ring method and Mirage densitometer. The surface tension deviations and excess molar volumes (Δσ, V E m) were calculated from the experimental results in different molar fractions. The Redlich-Kister polynomial equation was fitted to the surface tension deviations and the excess molar volume results.

Odor-Dependent Hemodynamic Responses Measured with NIRS in the Main Olfactory Bulb of Anesthetized Rats

In this study, we characterize the hemodynamic changes in the main olfactory bulb of anesthetized Sprague-Dawley (SD) rats with near-infrared spectroscopy (NIRS, ISS Imagent) during presentation of two different odorants. Odorants were presented for 10 seconds with clean air via an automatic odor stimulator. Odorants are: (i) plain air as a reference (Blank), (ii) 2-Heptanone (HEP), (iii) Isopropylbenzene (IB). Our results indicated that a plain air did not cause any change in the concentrations of oxygenated (Δ[HbO2]) and deoxygenated hemoglobin (Δ[Hbr]), but HEP and IB induced strong changes. Furthermore, these odor-specific changes had regional differences within the MOB. Our results suggest that NIRS technology might be a useful tool to identify of various odorants in a non-invasive manner using animals which has a superb olfactory system.