Production and Isolation of n‐Butyl Acrylate Using Pervaporation‐Aided Esterification Reaction: Kinetics and Optimization

Synthesis of n‐butyl acrylate by esterification of acrylic acid with n‐butyl alcohol was carried out in a batch membrane reactor. Optimization and design of the experiment was accomplished by response surface methodology with Box‐Behnken experimental design. The effects of different parameters like reaction temperature, catalyst concentration, molar ratio of alcohol to acid, and ratio of membrane surface to initial volume on water flux and conversion of acrylic acid were evaluated. A kinetic model for the esterification‐coupled pervaporation process was developed. Kinetic parameters were estimated by a nonlinear optimization technique in the MATLAB optimization toolbox. The experimental and simulation results were applied for developing a concept to effectively conduct a pilot‐scale esterification‐pervaporation experiment.     

Design and Control of Ionic Liquid‐Catalyzed Reactive Distillation for n‐Butyl Acetate Production

A simulation study of n‐butyl acetate production with the [Hpy][HSO₄] ionic liquid catalyst was performed. Due to the lack of phase equilibrium data, the binary interaction parameters of the NRTL model for ionic liquid and reactive species were calculated by the COSMO‐RS technique. A reactive distillation process with recycled ionic liquid stream was proposed, and the column configuration was optimized by minimization of the total annual capital. The novel process is considerably efficient and economic compared to the traditional reactive distillation process of nonionic liquids. With the steady‐state parameters, a plant‐wide control structure was further developed to evaluate the robustness of the control system by exerting the disturbances of feed flow rate and feed composition. Dynamic simulation results suggest that the control scheme with a composition controller is timely and effective.     

Study on the Synthesis of n‐Butyl Acetate by Catalytic Rectification

With Hβ zeolite as the catalyst and θ rings as the fillings, the technological process of synthesizing n‐butyl acetate with acetic acid and n‐butanol in a Φ 30 mm and 2 m tall catalytic rectifying column was studied. The influence of factors such as catalyst loading height, material feed site, reflux ratio and feed rate on the esterification reaction and the rectification effect was investigated. The study results suggested that the appropriate conditions of n‐butyl acetate synthesis by catalytic rectification include: The height ratio of the rectifying section, the reaction section and the stripping section is 1:1:1; acetic acid and n‐butanol are fed in upside and downside of the reaction section, respectively; the reflux ratio is 2.5; the liquid hourly space velocity of n‐butanol is 0.64 h^–1. Under these conditions, the mass fraction of n‐butyl acetate in the column bottom is 98.64 %, and the total yield of n‐butyl acetate is 91.5 %.     

Pervaporation of n‐butanol aqueous solution through ZSM‐5‐PEBA composite membranes

Composite membranes were prepared by incorporating ZSM‐5 zeolite into poly(ether‐block‐amide) (PEBA) membranes. These composite membranes were characterized by TGA, XRD, and SEM. The results showed that the zeolite could distribute well in the polymer matrix. And when the zeolite content reached 10%, the agglomeration of zeolite in the membranes was found. The composite membranes were used to the pervaporative separation of n‐butanol aqueous solution. The effect of zeolite content on pervaporation performance was investigated. With the contribution of preferential adsorption and diffusion of n‐butanol in the polymer matrix and zeolite channel, the 5% ZSM‐5‐PEBA membrane showed enhanced selectivity and flux. The effects of liquid temperature and concentration on separation performance were also investigated. All the composite membranes demonstrated increasing separation factor and permeation flux with increasing temperature and concentration. Incorporation of ZSM‐5 could decrease the activation energy of n‐butanol flux of the composite membrane. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Coproduction of Ethyl Acetate and n‐Butyl Acetate by Using a Reactive Dividing‐Wall Column

The performance of the reactive distillation dividing‐wall column for coproduction of ethyl acetate and butyl acetate was experimentally studied. n‐Butanol and ethanol are raw reaction materials that react with acetic acid in the reaction zone to produce n‐butyl acetate and ethyl acetate, respectively. n‐Butyl acetate is not only a product, but also acts to remove water generated by the esterification reactions. The effects of various parameters, such as catalyst loading per stage, reflux ratio, liquid split and molar feed ratios, ethyl acetate/n‐butyl acetate purity, pressure drop, and total energy consumption, are investigated. Results show that ethanol could be completely converted and the products could be easily separated, which shows great industrial application potential in the coproduction of ethyl acetate and n‐butyl acetate.     

Chemical kinetic modeling of i‐butane and n‐butane catalytic cracking reactions over HZSM‐5 zeolite

A chemical kinetic model for i‐butane and n‐butane catalytic cracking over synthesized HZSM‐5 zeolite, with SiO₂/Al₂O₃ = 484, and in a plug flow reactor under various operating conditions, has been developed. To estimate the kinetic parameters of catalytic cracking reactions of i‐butane and n‐butane, a lump kinetic model consisting of six reaction steps and five lumped components is proposed. This kinetic model is based on mechanistic aspects of catalytic cracking of paraffins into olefins. Furthermore, our model takes into account the effects of both protolytic and bimolecular mechanisms. The Levenberg–Marquardt algorithm was used to estimate kinetic parameters. Results from statistical F‐tests indicate that the kinetic models and the proposed model predictions are in satisfactory agreement with the experimental data obtained for both paraffin reactants. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2456–2465, 2012     

Mesoporous H‐ZSM‐5 for the Conversion of Dimethyl Ether to Hydrocarbons

The potential of hierarchical H‐ZSM‐5 zeolites was studied for the conversion of DME to fuel‐compatible hydrocarbons. For this purpose, hierarchical H‐ZSM‐5 zeolites have been prepared from commercial H‐ZSM‐5 by desilication and organosilane‐directed hydrothermal synthesis. The zeolites were characterized by X‐ray diffraction, NH₃‐TPD, DRIFTS, and N₂ physisorption measurements. The catalysts have been tested in a tube reactor (1 bar, 648 K). The results indicate important structural changes in framework and acidic sites, which are significant for the synthesis of gasoline‐range hydrocarbons.     

Migration of Potassium in an Fe2O3/H‐ZSM‐5 Composite Catalyst

The migration of potassium in an iron/H‐ZSM‐5 bifunctional system was investigated by pressing K/Fe₂O₃ and H‐ZSM‐5 in a pellet using 2 t of pressure. These pellets were heated at 350 °C in air for a number of days. Migration of potassium was visualized using energy‐dispersive X‐ray profiling. The distribution of potassium in the Fe₂O₃ phase and the H‐ZSM‐5 phase was approximately constant, with a step change over the phase boundary. The step change varied as a function of the heating time. The amount of potassium migrated from the Fe₂O₃ phase to the H‐ZSM‐5 phase was quantified using NH₃‐TPD. It is shown that an equilibrium distribution between potassium in the Fe₂O₃ phase and the H‐ZSM‐5 phase is obtained after ca. 7 days of heating.     

Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts

BACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon‐neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H‐ZSM‐5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds. RESULTS: Successive addition of Fe and P to the H‐ZSM‐5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co‐addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on‐stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air. CONCLUSION: Fe‐ and/or P‐modified H‐ZSM‐5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air. Copyright © 2010 Society of Chemical Industry     

Efficient Acylation of Anisole over Hierarchical Porous ZSM‐5 Structure

Friedel‐Crafts acylation is one of the most important methods to prepare aromatic ketones which are used in manufacturing fine and speciality chemicals, as well as pharmaceuticals. Herein, we report an efficient and convenient procedure for the acylation of anisole with acetic anhydride, using a hierarchical porous ZSM‐5 catalyst. The hierarchical porous ZSM‐5 catalyst was synthesized using styrene butadiene rubber (SBR) as macroporous template. The catalysts were characterized for their structural features by using XRD, SEM, and FT‐IR analyses. The effect of temperature, molar ratio, and catalyst weight on the acylation of anisole was studied in detail. The reaction parameters such as anisole‐to‐acetic anhydride mole ratio, catalyst weight, and reaction temperature were optimized as 5:1, 0.2 g, and 70 °C, respectively. The method described here is environmentally benign and replaces the conventional catalyst by a highly active and reusable catalyst.     

Deoxygenation of Methanol over ZSM‐5 in a High‐Pressure Catalytic Pyroprobe

Deoxygenation is a critical step in making hydrocarbon‐rich biofuels from biomass constituents. Although the thermal effects of oxygenate aromatization have been widely reported, the effect of pressure on this critical reaction has not yet been closely investigated, one primary reason being the unavailability of a reactor that can pyrolyze oxygenates, especially those in solid form, under pressurized conditions. Here, the first of a series of studies on how oxygenates behave when catalytically pyrolyzed under elevated pressure and temperature conditions is reported. Methanol, the simplest alcohol, was selected as the candidate to study the chemical phenomena that occur under pressurized catalytic pyrolysis. The reactions were carried out over the shape‐selective catalyst ZSM‐5 (SiO₂/Al₂O₃ = 30) under varying pressure (0 to 2.0684 MPa (300 psi) in 0.3447 MPa (50 psi) increments) and temperature (500 to 800 °C in 50 °C increments) conditions. Benzene, toluene, ethyl benzene, and xylenes (BTEX) were analyzed as the deoxygenated products of the reaction. The results indicate that the reactor pressure significantly affects deoxygenated product composition.     

Catalytic combustion kinetics of isopropanol over novel porous microfibrous‐structured ZSM‐5 coating/PSSF catalyst

Porous thin‐sheet cobalt–copper–manganese mixed oxides modified microfibrous‐structured ZSM‐5 coating/PSSF catalysts were developed by the papermaking/sintering process, secondary growth process, and incipient wetness impregnating method. Paper‐like sintered stainless steel fibers (PSSF) support with sinter‐locked three‐dimensional networks was built by the papermaking/sintering process, and ZSM‐5 coatings were fabricated on the surface of stainless steel fibers by the secondary growth process. Catalytic combustion performances of isopropanol at different concentrations over the microfibrous‐structured Co–Cu–Mn (1:1:1)/ZSM‐5 coating/PSSF catalysts were measured to obtain kinetics data. The catalytic combustion kinetics was investigated using power–rate law model and Mars–Van Krevelen model. It was found that the Mars–Van Krevelen model provided fairly good fits to the kinetic data. The catalytic combustion reaction occurred by interaction between isopropanol molecule and oxygen‐rich centers of modified microfibrous‐structured ZSM‐5 coating/PSSF catalyst. The reaction activation energies for the reduction and oxidation steps are 60.3 and 57.19 kJ/mol, respectively. © 2014 American Institute of Chemical Engineers AIChE J, 61: 620–630, 2015     

Kinetics of glycerol conversion to hydrocarbon fuels over Pd/H‐ZSM‐5 catalyst

The utilization of glycerol, primary byproduct of biodiesel production, is important to enhance process economics. In our recent prior work, it was shown that glycerol can be converted to hydrocarbon fuels over bifunctional catalysts, containing a noble metal supported on H‐ZSM‐5. Over Pd/H‐ZSM‐5 catalyst, an optimal ～60% yield of hydrocarbon fuels was obtained. In the present work, based on experimental data over Pd/H‐ZSM‐5 catalyst, a lumped reaction network and kinetic model are developed. Using differential kinetic experiments over the temperature range 300–450°C, the rate constants, reaction orders, and activation energies are obtained for each reaction step. The predicted values match well with experimental data for glycerol conversion up to ～90%. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5445–5451, 2017     

Catalytic para‐xylene maximization: III. Hydroisomerization of meta‐xylene on H‐ZSM‐5 catalysts containing different platinum contents

Hydroisomerization of meta‐xylene was carried out using catalysts containing 0.15–0.60 wt% Pt on H‐ZSM‐5 zeolite, in a pulsed microreactor system connected to a gas chromatograph at a flow of hydrogen of 20 cm³ min⁻¹ and temperatures of 275–500 °C. Increasing temperature, increased isomerization with low rates. Increasing Pt content of the catalyst, decreased hydrodealkylation considerably via masking strong acid sites as revealed by temperature programmed desorption of ammonia measurements. Formation of trimethylbenzenes was inhibited by Pt incorporation in the H‐ZSM‐5 zeolite. The activation energies obtained for meta‐xylene hydroisomerization were relatively low (24.4–61.6 kJ mol⁻¹) on all catalysts under study. Para‐xylene yields in the xylenes mixture of product relative to the corresponding thermodynamic equilibrium values amount to about 0.8–0.9 at temperatures of 400–500 °C but were lower at lower temperatures. © 1999 Society of Chemical Industry     

Direct Extraction of Propionic Acid from Propionibacterium acidipropionici Broths with Tri‐n‐octylamine

The direct reactive extraction of propionic acid from Propionibacterium acidipropionici broths with solutions of tri‐n‐octylamine in dichloromethane, n‐butyl acetate or n‐heptane underlined the strong negative influence of the cells, due to the blockage of the interface by their adsorption. The magnitude of this effect <#>depends on the affinity of the cells for the organic phase, which is more important for n‐heptane, but only at biomass concentrations below 18 g L^–1 d.w. (dry weight). Moreover, the interfacial mass transfer of the acid is also controlled by the solvent polarity, and is accelerated from n‐heptane to dichloromethane and by the addition to the organic phase of 1‐octanol as a phase modifier. The influences of the biomass concentration, the rotation speed and the solvent dielectric constant were included in a mathematical model describing the solute mass flow from the aqueous to the organic phase.     

Performance of H‐ZSM‐5‐supported bimetallic catalysts for the combustion of polluting volatile organic compounds in air

The performance of H‐ZSM‐5‐supported bimetallic catalysts with chromium as the base metal in the combustion of ethyl acetate and benzene is reported. A reactor operated from 100 to 500 °C at a gas hourly space velocity (GHSV) of 32 000 h^?1 was used for study of the activity. A combination of 1.0 wt% chromium and 0.5 wt% copper yielded a catalyst (Cr_1.0Cu_0.5/Z) with improved conversion and carbon dioxide yield. Cr₂O₃ (Cr³⁺) and CuO (Cu²⁺) were the predominant metal species in the catalyst. In agreement with the Mars–van Krevelen model, improved reducibility of Cr³⁺ in the presence of Cu²⁺ led to an improvement in activity. The copper content in Cr_1.0Cu_0.5/Z also favored the formation of deep combustion products. Condensation and subsequent growth of coke precursors in the catalyst pores led to the formation of a softer and less aromatic coke fraction while dehydrogenation activity on acid sites formed a harder and more aromatic coke fraction. The use of Cr_1.0Cu_0.5/Z favored the formation of lower molecular weight intermediates, leading to reduction in formation of softer coke. Copyright © 2005 Society of Chemical Industry