Alkylation Of Aromatic Hydrocarbons Research Articles

Effect of Poly(vinyl alcohol) on Catalytic Performance of Al-Pillared Clay in Alkylation of Aromatic Hydrocarbons with Olefins

It is vital to design and synthesize efficient catalysts for removing olefins from aromatics and prolonging reaction time. The catalytic properties of pillared clay for olefin removal from aromatic compounds can be enhanced noticeably by grafting organic polymer molecules due to modification of the clay porosity in the pillaring reaction. In the present work, a series of catalysts are prepared by pillaring raw bentonite and acid-treated bentonite with aluminum and poly(vinyl alcohol) (PVA) intercalation. Prepared samples are evaluated in the olefin removal process and characterized by X-ray diffraction patterns (XRD), temperature-programmed desorption (TPD) of NH3, and nitrogen adsorption–desorption isotherms. The BET results reveal that the pillaring reaction in an aqueous solution of PVA increases the clay’s surface area to greater than 200 m2.g–1. The pore volume of alumina-pillared acid-activated clay (Al-PAAC) is enhanced from 0.278 to 0.321 and 0.416 cm3.g–1 at the PVA concentrations of 30 and 50 wt %, respectively. The samples modified with PVA, as a precursor in the pillaring reaction, show an enhanced catalytic activity compared to the other samples due to a higher number of active sites. The olefin conversion of the pillared sample remains above 50% in the presence of 50 wt % PVA for more than 26 h. Furthermore, PVA could facilitate the reactant’s access to the active acid sites in the interlayer of the pillared clay. The adsorption of aromatic compounds and olefins by the pillared samples follows the intraparticle diffusion kinetic model. In addition, the Langmuir model fits the adsorption isotherm data well.

Design of Binary Nb2O5-SiO2 Self-Standing Monoliths Bearing Hierarchical Porosity and Their Efficient Friedel-Crafts Alkylation/Acylation Catalytic Properties.

Alkylation of aromatic hydrocarbons is among the most industrially important reactions, employing acid catalysts such as AlCl3, H2SO4, HF, or H3PO4. However, these catalysts present severe drawbacks, such as low selectivity and high corrosiveness. Taking advantage of the intrinsic high acid strength and Lewis and Brønsted acidity of niobium oxide, we have designed the first series of Nb2O5-SiO2(HIPE) monolithic catalysts bearing multiscale porosity through the integration of a sol-gel process and the physical chemistry of complex fluids. The MUB-105 series offers efficient solvent-free heterogeneous catalysis toward Friedel-Crafts monoalkylation and -acylation reactions, where 100% conversion has been reached at 140 °C while cycling. Alkylation reactions employing the MUB-105(1) catalyst have a maximum turnover number (TON) of 104 and a turnover frequency (TOF) of 9 h-1, whereas for acylation, MUB-105(1) and MUB-105(2) yield maximum TON and TOF values of 107 and 11 h-1, respectively. Moreover, the catalysts are selective, producing equal amounts of ortho- and para-substituted alkylated products and greater than 90% of the para-substituted acylated product. The highest catalytic efficiencies are obtained for the MUB-105(1) catalyst, bearing the smallest Nb2O5 particle sizes, lowest Nb2O5 content, and the highest amorphous character. The catalysts presented here are in a monolithic self-standing state, offering easy handling, reusability, and separation from the final products.

Study on the alkylation of aromatic hydrocarbons and propylene

In order to improve the efficiency of the alkylation reaction to aromatic hydrocarbons and propylene, different types of catalysts were screened, including ultra-stable Y molecular sieves (USY), solid phosphoric acid (SPA), ZSM type molecular sieve (HZSM), etc. The effects of reaction temperature, catalyst loading, and reaction time on the conversion rate of aromatic hydrocarbons and the selectivity of target products were investigated using the high-pressure reaction device. The catalysts were characterized by XRD, BET, SEM, FT-IR, NH3-TPD, and other methods. The experimental results show that the USY catalyst exhibits higher catalytic activity for alkylation. This catalyst can be used for the alkylation of different aromatic hydrocarbons. Good conversion and selectivity can be obtained. Futhermore, in a six-cycle experiment, the USY catalyst was reused without loss of efficiency.

Study on the alkylation of aromatic hydrocarbons and propylene.

In order to improve the efficiency of the alkylation reaction to aromatic hydrocarbons and propylene, different types of catalysts were screened, including ultra-stable Y molecular sieves (USY), solid phosphoric acid (SPA), ZSM type molecular sieve (HZSM), etc. The effects of reaction temperature, catalyst loading, and reaction time on the conversion rate of aromatic hydrocarbons and the selectivity of target products were investigated using the high-pressure reaction device. The catalysts were characterized by XRD, BET, SEM, FT-IR, NH3-TPD, and other methods. The experimental results show that the USY catalyst exhibits higher catalytic activity for alkylation. This catalyst can be used for the alkylation of different aromatic hydrocarbons. Good conversion and selectivity can be obtained. Futhermore, in a six-cycle experiment, the USY catalyst was reused without loss of efficiency.

Synthesis of a robust regulator in the process of alkylation of benzene by propylene in the liquid prase

The alkylation process is complementary to the catalytic cracking process. These processes are one of the most important in the manufacture of petroleum products. Therefore, it is advisable to increase the efficiency of production and development of a control system for the process of alkylation of benzene with propylene in the liquid phase.To compile a mathematical model of the alkylation process, taking into account the physico-chemical features of the process, it is necessary to have an idea of its mechanism. Alkylation reactions are exothermic and lead to the appearance of mono- and polyalkylation products, accompanied by side reactions of isomerization, polymerization and depolymerization. In the alkylation of aromatic hydrocarbons, in particular benzene, the greatest industrial value is aluminum chloride AlCl3, which has a number of significant advantages over other catalysts. However, it has been established that in the presence of AlCl3 in the composition of the catalytic complex, ternary complexes can be formed not only with one, but also with two, three and so on hydrocarbon radicals. Complexes can enter into metabolic reactions not only with benzene, but also with the reaction products, for example, with dipropylbenzene, then there is a process of alkylation and there are a significant number of side reactions. As a result of these reactions, the value of the preexponential multiplier and the activation energy in the Arrhenius equation change. And the activity of the catalyst with the time of operation is often reduced and this significantly affects the final product. In this work, the actual values of the specific conductivity of the catalyst were normalized in the range from 0 to 1.As a result of processing a large array of experimental data, it was found that the maintenance of the activity of the rotary catalyst complex is regulated by the consumption of fresh catalyst and as a result depends on the consumption of the rotary catalyst, its activity and the activity of fresh catalytic complex.The experience of using optimal systems according to the quadratic quality criterion has shown their sensitivity to the process parameters of a real object. Such systems turned out to be rude, which leads to their loss not only of optimality, but also of stability and quality.It is proposed to create a control system that would take into account these parametric uncertainties.The synthesis of a robust regulator allowed to take into account all the unpredictable disturbances that affect the process while improving the quality of the product, its speed and optimal use of the catalytic complex. And since the alkylation processes are similar, this control system can be used for other mathematical models of the process.Synthesis of a robust regulator in the process of alkylation of benzene by propylene in the liquid prase

Alkylation of Aromatic Hydrocarbons with 2-Methyl-2-Vinyl-gem-Dichlorocyclopropane over Zeolite Catalysts

It has been found as a result of the investigation of the catalytic properties of various microporous zeolites (of FAU, BEA, MOR, and MFI structural types) and a micro–meso–macroporous H-Ymmm zeolite (FAU) in the alkylation reaction of arenes (benzene (II) and toluene (III)) with the unsaturated compound 2-methyl-2-vinyl-gem-dichlorocyclopropane (I) that the reaction proceeds with the formation of chloroalkylarenes [1-(2,2-dichloro-1-methylcyclopropyl)ethyl]benzene (IV) and 1-[1-(2,2-dichloro-1-methylcyclopropyl)ethyl]-4-methylbenzene(V). Compounds IV and V are the most selectively formed over H-Beta (up to 82%) and H-Ymmm (up to 79%) zeolite catalysts with a high conversion of I (from 90% to full). It has been shown that high selectivity for chloroalkylarenes IV and V is achieved at 100°C, an arene : unsaturated compound molar ratio of 8 : 1, a catalyst concentration of 20 wt % of the reaction mass, and a reaction time of 2 h.

Toluene Methylation by Methyl Mercaptan and Methanol over Zeolites—A Comparative Study

In this study, we show that the Friedel–Crafts (FC) alkylation of aromatic hydrocarbons by thiols to form C–C bond is feasible. The gas-phase reaction between toluene and CH3SH catalyzed by HZSM-5 zeolite was chosen as model reaction. In the temperature range of 350–550 °C, the alkylation of toluene to produce xylenes was the main reaction involved in the process. The reaction between toluene and CH3SH was compared with the well-known reaction between toluene and CH3OH. Significant similarities exist, notably the ability of both CH3SH and CH3OH to generate methoxonium species on the zeolite surface and to methylate the aromatic ring in a typical FC process. The maximum alkylation yield of 41% for CH3OH was reached at 350 °C, while that of 67.3% for CH3SH was reached at 450 °C. This difference in temperature can be correlated with the energy barriers required for the formation of methoxonium species (i.e., 24.6 kcal/mol (CH3OH) and 26.4 kcal/mol (CH3SH)). The high performance in alkylation proved by CH3SH ...

Spectroscopic Evidence for the Involvement of a Radical Intermediate in the Friedel-Crafts Benzylation Using Ion-Exchanged K10 Catalysts

For Friedel-Crafts alkylation of aromatic hydrocarbons an ionic reaction path is considered as classical reaction mechanism. The alkylation with benzyl chloride in the presence of ion-exchanged K10 montmorillonite catalysts containing multivalent, reducible cations had an outstanding activity, therefore a radical initial step as a supplement to the ionic mechanism was proposed earlier. We made ESR investigations to clarify the existence and the nature of the suggested radical species. The ESR experiments verified that the reaction involves a radical step.

New rearrangement of substituted chloromethyl-gem-dichlorocyclopropanes under Friedel-Crafts reaction conditions

189 Alkylation of aromatic hydrocarbons with chlo romethyl gem dichlorocyclopropanes in the presence of Lewis acids is known to result in gem dichloroalke nyl derivatives [1]. We revealed that the reaction of 2,2 dimethyl 3 chloromethyl gem dichlorocyclopropane (III) with benzene (I) and toluene (II) leads to gem dimethyl alkenearomatic hydrocarbons (IV, Va, Vb) with vicinal arrangement of chlorine atoms.

Alkylation of aromatic hydrocarbons with 2-bromo-2-phenyl-gem-dichlorocyclopropane

The alkylation of aromatic hydrocarbons with 2-bromo-2-phenyl-gem-dichlorocyclopropane in the presence of catalytic quantities of aluminum chloride was found to afford the corresponding 2-aryl-3-phenyl-1,1-dichloroprop-1-enes. It was shown that the yield of the alkylation products depended on the nature of substituents in the aromatic ring. Compared with the thermal heating, microwave irradiation allows reducing the reaction time and increasing the yield of the corresponding 2-aryl-3-phenyl-1,1-di-chloroprop-1-enes, wherein the ortho-/para-isomers ratio changes.

Mechanochemical processing of oil residues

The feasibility of processing heavy-oil resid by mechanochemical action is explored. It is shown that hydrocarbon destruction and condensation processes occur in equal measure. The n-paraffins C6-C16 are subject to destruction, and the condensation processes are associated with alkylation of aromatic hydrocarbons by paraffin-destruction products. C16+ paraffins are formed during mechanochemical destruction of the paraffins.

ChemInform Abstract: High Catalytic Activity of an Insoluble Acidic Caesium Salt of Dodecatungstophosphoric Acid for Liquid-Phase Alkylation.

The use of solid acid catalysts is often desirable for liquid-phase reactions [1] in the place of homogeneous catalysts such as H2SO4 [2] and HA12CI: [2,3]. Among the various solid acids that were tested for liquid-phase alkylation of aromatic hydrocarbons [4-8], perfluorinated resinsulfonic acid (Nation-H) has been reported as being a good catalyst [4,5]. The authors have previously found that solid heteropoly compounds, H3PW1204o and their acidic caesium salt, where highly active catalysts for the dehydration of alcohols in the gas phase [9-12] and for the decomposition of ester in the liquid phase [ 13 ]. Here we wish to report on the high activities of Ho.sCs2.~PW12040 for the alkylation of aromatic compounds with cyclohexene. This catalyst was found to be much more active than HY, H-ZSM-5, and Nafion-H. Ho..~Cs2.sPW1204o (abbreviated as Cs2.5-salt) was obtained as a precipitate by the titration of an aqueous solution of H3PWI2QO (Nippon Inorganic Colour and Chemicals) with an aqueous solution of Cs2CO3 as described before [9-13 ]. Carbon-supported H3PW~204o [14] was prepared with an activated carbon (Wako Pure Chemicals) and an aqueous solution of H3PW~204o. The amount of H3PWI204o loaded was 18 wt.-%. This is denoted by H3PW~204o/ AC. SiO2-A12Os (SA-1, Catalysts and Chemicals Industries; A1203 : 13 wt.-% ), Nafion-H (NR-50, Mitsui Toatsu Fine Chemicals), H-ZSM-5 (25H, Mobil Catalysts Company of Japan), HY-zeolite (prepared from SK-40, Linde), aluminium exchanged montmorillonite (prepared from Kunipia-F, Kunimine Kogyo), H2SO4-treated ZrO~ (abbreviated as SO42-/ZrO2) [15,16], and HA12C17 [3] were used as reference catalysts.

Combining alkylation and transalkylation for alkylaromatic production

The alkylation of aromatic hydrocarbons with olefins is applied on a large scale in the chemical industry. The efficiency of these productions is highly improved performing alkylation combined with transalkylation, the latter allowing conversion of some low valued by-products such as polyalkylbenzenes into their monosubstituted homologues. The aim of this contribution is to summarize some examples of novel industrial processes, based on new catalysts that are environmentally friendly, for the production of ethylbenzene and cumene, two of the most important chemicals produced by alkylation/transalkylation.

Uptake and Dupuration of Petroleum Hydrocarbons By the Backwater Clam,Meretrix CastaChemnitz

Abstract Meretrix casta were experimentally exposed to water soluble fractions of refined and crude oil and their rate of accumulation of the petroleum hydrocarbons including total and individual aromatics viz., naphthalene, methylnaphthalene and dimethylnaphthalene, was studied. Subsequent transfer to clean waters in the laboratory and field resulted in depuration of the accumulated hydrocarbons from tissues. in general, the rate of discharge was found to be dependent on the concentration that the animals had been earlier exposed to and also the alkylation of aromatic hydrocarbons. Occasional increases were observed in the hydrocarbon values of clams which were placed in the field, compared to their laboratory counterparts, suggesting an intermittent source of petroleum hydrocarbon input into the environment. the influence on the rate of uptake, release and retention of hydrocarbons in the clams is discussed.

Alkylation of aromatic hydrocarbons over metalimpregnated zeolite catalysts

Alkylation of aromatic hydrocarbons over metalimpregnated zeolite catalysts

Reductive alkylation of aromatic hydrocarbons

Reductive alkylation of aromatic hydrocarbons

ChemInform Abstract: Alkylation of Aromatic Hydrocarbons with 1‐Fluoromethyl‐o(m)‐carboranes Under the Action of AlCl3.

AbstractThe fluoromethylcarboranes (I) and (V) react with benzene (II) under Friedel‐Crafts conditions to give the benzylcarboranes (III) and (VI).

Alkylation of aromatic hydrocarbons by 1-fluoromethyl-o,m-carboranes by the action of AlCl3

1-Fluoromethyl-o, m-carboranes undergo the Friedel-Crafts reaction with aromatic hydrocarbons in the presence of AlCl3.

Alkylation of Aromatic Hydrocarbons with Divinylbenzene by Solid Polymeric Oxo Acids

Alkylation of Aromatic Hydrocarbons with Divinylbenzene by Solid Polymeric Oxo Acids

Determination of process conditions for alkylation of toluene with ethylene and propylene on Al2O3 promoted with boron fluoride

It had been shown previously [1–3] that commercial A12O3 promoted with boron fluoride is an active catalyst for the alkylation of aromatic hydrocarbons with olefins. In this article, we are presenting results from a study of the alkylation of toluene with ethylene and propylene, directed toward the production of ethyltoluenes and cymenes.