Synthesis Of Methyl Tert-butyl Ether Research Articles

Extraction mechanism analysis and energy saving enhancement of extraction separation of methyl tert-butyl ether and methanol by ionic liquid based on molecular dynamics simulation

• The ILs extractant is screened by quantum chemistry and MD simulation. • The process flow of applying ILs in the production of MTBE was designed. • The sequential iterative optimization integrating reaction conditions is proposed. • The TAC in MTBE production was reduced by 26.77% when applying ILs. Methyl tert-butyl ether as an excellent gasoline additive has been widely used. There are a lot of mixtures of Methyl tert-butyl ether and methanol in the process of Methyl tert-butyl ether production. In this work, the interaction between different ionic liquids and methyl tert butyl ether / methanol was studied by the combination of quantum chemistry and molecular dynamics. In addition, there is little difference between the experimental data and the MD simulation results, indicating that the extraction performance can be predicted by MD simulation even without the phase equilibrium data. The interaction energy, radial and spatial distribution functions, and self-diffusion coefficients are calculated based on the molecular dynamics simulation results. It is proved that anions play a key role in the extraction process. The process of synthesis of methyl tert-butyl ether with ionic liquid extraction as separation unit was studied and the optimum process parameters were determined. Methyl tert-butyl ether with mole fraction greater than 99.9% could be obtained by ionic liquid extraction, and the use of Ionic liquids liquid-liquid extraction can save 26.77% of total annual cost than extractive distillation using conventional solvents. It plays a guiding role in the selection of green solvent ionic liquids extractant and the energy saving of liquid-liquid extraction.

Modelling of heat integrated reactive distillation column (r-HIDiC): Simulation studies of MTBE synthesis

In the present study, heat integrated distillation column is modelled and simulated for the production of Methyl tert-Butyl Ether (MTBE) from methanol and isobutylene using ASPEN Plus®. Also, the objective of this study is to have comparative analysis between the reactive distillation process and an alternative intensified process (r-HIDiC) to produce MTBE. Rigorous simulation study has been conducted to compare the optimal flow sheet of the above two designs. Temperature and composition profiles are studied and compared for both the models and found that the temperature at the last stage of the stripping section in r-HIDiC is 406 K while that of the stripping section in RDC is 427.24 K. This reduced temperature decreases the composition of methanol in bottom product in stripping column in case of r-HIDiC as methanol forms a homogenous azeotrope with MTBE at 408.53 K. Also, it is found that, although with nominal increase in TAC i.e. 16.56%, in r-HIDiC design as compared to the reactive distillation column design which is caused due to the high cost of the additional compressor needed in the vapour compression, however, the r-HIDiC design can save reboiler and condenser heat duties to a considerable amount i.e. by 35.06% and 36.65% respectively.

Distillation process optimization using continuous mobile control actions by redistributing the feed flow

Object. Systems of the distillation processes automatic control, that provide extreme quality indicators of the column functioning using mobile control actions and a nonlinear predictive simulation. Subject. A method for optimizing the distillation process using continuous mobile control actions in the feed flow redistribution between the apparatus’ contact devices. Aim. The method development for computation of optimal control actions on the process of multicomponent distillation, including continuous mobile actions, that provide optimal operating modes for columns according to criteria for productivity maximization and energy costs minimization. Results. The static simulation allowed computing the concentration profiles of the column for the separation of the methyl tert-butyl ether synthesis products (MTBE) and it was proved that the feed flow redistribution between two contact devices can significantly affect the apparatus’ static characteristics, meanwhile the quality of the target product is extremely dependent on the redistribution coefficient. The choice of the feed tray is justified considering the criterial losses on the contact devices of the column. The problem of the multicomponent distillation process optimizing for a normalized criterion, which simultaneously includes the process productivity and the energy consumption for its conduct, is solved. The selected criterion extremely depends on the magnitude of the continuous control action, that determines the existence and uniqueness of the optimization problem solution. Conclusions. It is proved that the continuous mobile actions allow providing many modes of operation of the column, unattainable in the class of traditional and discrete, and to improve the technical and economic performance of the process compared with cases of full feed supply to any of the trays. The research’s results can be used in solving problems of designing and optimizing the operation modes of distillation apparatuses, for making automatic control systems for distillation processes.

A novel disposal approach of deactivated resin catalyst for methyl tert-butyl ether synthesis: Preparation of low-cost activated carbons with remarkable performance on dibenzothiophene adsorption

In this research, low-cost activated carbons (ACs) derived from deactivated resin catalyst (DRC) for methyl tert-butyl ether synthesis were successfully prepared through carbonization and subsequent steam activation or KOH activation. Differences in physical and chemical properties of ACs and their performance on dibenzothiophene (DBT) adsorption from model fuel were investigated systematically. AC prepared by KOH activation (KSAC) has abundant micropores, whereas mesopores are the major part of AC prepared by steam activation (HSAC). Both KSAC and HSAC have few acidic groups, in accordance with their oxygen content. DBT adsorption performance is dependent largely on physical properties. The maximum adsorption capacity (16.1mgS/g at 100ppmS) and the longest breakthrough time (16h, 10h−1WHSV) were observed for KSAC.

The Investigation of the Selected Parameters of Catalysis on the Effectiveness Factor of MTBE Synthesis in the Case of a Pellet Catalyst

The influence of selected parameters on the effectiveness factor of catalyst particles for the synthesis reaction of methyl tert-butyl ether (MTBE) from methanol and isobutene is analyzed. The catalyst is the sulfonated ion-exchange resin Bayer K2631. To this aim, the mass and heat balance equations that are presented as a system of differential equations, has been solved by means of the commercial mathematical software MathCad, for which a tailor - made program has been created. Four chosen parameters (tortuosity, particle radius, methanol to isobutene molar ratio and temperature) have been considered to carry out the calculations. The obtained results have been analyzed and presented in a graphical form. They show that the effectiveness factor can be equal, lower or higher than unity depending on the value of the considered parameters. The effectiveness factor is mainly dependent on mass and heat diffusional limitations at certain reaction conditions.

Control of a reactive distillation process: MTBE synthesis

This paper explores the closed-loop control performance of a heterogeneously catalysed reactive distillation process for the synthesis of methyl tert-butyl ether (MTBE). Two fresh reactant feed streams, namely methanol (MeOH) and mixed butenes, are introduced in the column. Distillate containing mostly n-butene (NB) and bottoms enriched with MTBE are collected from the process. Obviously, the stoichiometric amounts of fresh feeds are desired. The proposed control algorithm uses a composition analyser in the reactive section of the column to detect the inventory of MeOH so that fresh MeOH feed rate can be adjusted to satisfy the reaction stoichiometry. In addition, the closed-loop configuration includes two product compositions, two liquid levels, column pressure and fresh mixed butenes rate control loops. The developed control strategy provides tight control of MTBE product composition in presence of large disturbance and measurement lag.

ChemInform Abstract: Kinetics of Liquid Phase Synthesis of Methyl tert-Butyl Ether from tert-Butyl Alcohol and Methanol Catalyzed by Ion Exchange Resin

Synthesis of methyl tert-butyl ether (abbreviated as MTBE) from methanol (MeOH) and tert-butyl alcohol (TBA) in the liquid phase was studied by using Amberlyst 15 in the H+ form as an acid catalyst. Experiments were carried out in a stirred batch reactor at different temperatures (313, 318, and 323 K) under atmospheric pressure. It was found that catalyst sizes and rotation speeds had no significant effects on reaction rates. Mechanism studies showed that three reactions took place simultaneously. It was also found that dehydration of TBA could not be neglected. The experimental concentration profiles with time could be simulated well by simple kinetics. Finally, rate constants could be expressed by Arrhenius equations. © 1993 John Wiley & Sons, Inc.

Bifurcation analysis for MTBE synthesis in a suspension catalytic distillation column

A rigorous bifurcation study is presented of methyl tert-butyl ether synthesis by suspension catalytic distillation (SCD). SCD is a new development of catalytic distillation (CD) in which fine catalyst particles are suspended in liquid, not only inherits advantages of CD but overcomes transfer limitations in catalyst bed. A complete equilibrium stage model is developed. Analysis results show that this system is sensitive to the operating parameters: the reflux ratio, the bottom flowrate, the methanol feed, the n-butane feed and the operation pressure, and the characteristic parameter for SCD: the solid/liquid separator ratio. The bifurcation diagram displays very intricate and highly nonlinear steady-state behavior, which can results in as many as seven steady-state solutions for identical column specifications. Especially, the results reveal that the superior column performance can be reached under practical operating conditions because the upper bound of the multiplicity range for the solid/liquid separation ratio is very small.

Selective Methyl Tert-Butyl Ether Synthesis over Metal Exchanged Pillared Clays

Iron and mixed iron aluminium pillared montmorillonites prepared by partial hydrolysis method was subjected to room temperature exchange with transition metals of the first series. The materials exhibit good structural as well as thermal stability. Exchanged metals were found to be present inside the porous network, in the environs of the pillars. Mixed pillaring resulted in the intercalation of Al13 like polymers in which Al is partially substituted by Fe. The acidic structure was followed by temperature programmed desorption of ammonia and cumene cracking test reaction. Weak and medium sites overshadow the strong sites in all systems. However, exchange with metals increases the number of strong sites. The prepared materials are efficient catalysts for gas phase MTBE synthesis. The catalytic activity can be well correlated with the total amount of weak and medium acid sites.

Global optimization of reactive distillation networks using IDEAS

In this work, we present a methodology for the global optimization of reactive distillation (RD) networks, through the Infinite DimEnsionAl State-space (IDEAS) approach. Within the IDEAS framework, network synthesis is formulated as an infinite dimensional linear optimization problem. The IDEAS conceptual framework is realized through solution of a series of finite dimensional linear programs whose optimum values converge to the infinite program’s infimum. The proposed optimal design methodology is demonstrated on a case study involving reactive distillation-based synthesis of methyl tert-butyl ether (MTBE) from isobutene and methanol.

Heteropolyacid (HPA)‐Polymer Composite Films as Heterogeneous Catalysts and Catalytic Membranes

AbstractFor Abstract see ChemInform Abstract in Full Text.

Feasibility of equilibrium-controlled reactive distillation process: application of residue curve mapping

The residue curve mapping technique (RCM) has been considered a powerful tool for the flow-sheet development and preliminary design of conventional multi-component separation processes. It does not only represent a good approximation to actual equilibrium behavior, but also it allows performing feasibility analysis of separation processes where non-ideal and azeotropic mixtures are involved. Applications of RCM to reactive distillation processes have recently been reported, but a generalized and systematic approach is still missing for the case of reactive feeds outside the conventional composition ranges and represents the aim of this contribution. An RCM-based feasibility analysis has been applied to the homogeneous reactive distillation synthesis of methyl tert-butyl ether (MTBE) at 11 atm from isobutene (IB) and methanol (MeOH) and in the presence of n-Butane ( nC 4). The reaction space, defined in terms of transformed composition variables, has been divided into sub-regions characterized by separation boundaries. A feasibility analysis of the reactive distillation process has been performed based upon the location of the reacting mixture, defined by [ x MeOH F, x IB F, x nC 4 ]∈[0, 1], and initial separation sequences have been generated according to the feed transformed-composition. In all the cases, high purity MTBE has been obtained.

The formation of MTBE on supported and unsupported H4SiW12O40

Sulphonated resins used in the industry as the catalysts in the synthesis of methyl tert-butyl ether (MTBE) until now, the most important anti-knocking additive to the gasoline, are not satisfactory because of environmental reasons and catalyst’s not adequate stability. This stimulates the search for new catalysts for this process. Among others heteropoly acids (HPA) are considered to be prospective ones. The present paper is the review of the authors’ investigations on physical chemistry of the MTBE synthesis in gas phase on dodecatungstosilicic acid H4SiW12O40 (HSiW). It has been preceded by the study of the interaction of both substrates, methanol and iso-butylene and the product MTBE, with crystalline HSiW comprising classical sorption experiments, FTIR and calorimetric measurements. Together with reaction kinetic measurements it enabled to propose the mechanism of the catalytic reaction according to which iso-butylene not penetrating the bulk of HSiW crystallites gets protonated at the surface with the loosely bonded protons (protons forming hydrogen bond between HSiW anions) and subsequently reacts with methanol from next-to-surface layer or from the gas phase. Methanol penetrating into the bulk is forming protonated clusters thus diminishing the concentration of loosely bonded protons. At high enough methanol concentration this leads to the diminishing of the formation rate of carbocation. In the result reaction order positive at the initial state of catalytic process (low bulk concentration of methanol and high concentration of loose protons) turns into negative at the reaction steady state. A set of kinetic equations has been proposed describing all these processes. A series of oxide supports: SiO2, TiO2, SiO2-Al2O3, γ-Al2O3 and AlPO4 with increasing basicity (characterised by the net oxygen negative charge calculated according to Sanderson’s theorem) was used for the preparation of HSiW supported catalysts. It has been shown that the activity decreases with the increasing basicity as a result of strong bonding protons by the surface of the support.

Heteropolyacid (HPA)-polymer composite films as heterogeneous catalysts and catalytic membranes

Preparation, characterization, and catalytic application of membrane-like heteropolyacid (HPA)-polymer composite films as heterogeneous catalysts and catalytic membranes were reported in this work. HPA-polymer composite film catalysts were prepared by a membrane preparation technique by blending HPA with polymer using a common or a mixed solvent. HPA-polymer composite film catalysts were cut into small pieces, and they were applied as heterogeneous catalysts to the liquid-phase tert-butyl alcohol (TBA) synthesis, to the vapor-phase ethyl tert-butyl ether (ETBE) synthesis, and to the vapor-phase ethanol conversion. It was observed that HPA catalysts were finely dispersed throughout the polymer supports, and the blending patterns of the composite film catalysts were different depending on the identity of solvent and polymer material used. The HPA-polymer composite films showed enhanced catalytic activities in these reactions compared to the mother HPAs. Pore characteristics of the composite film catalysts could be controlled by a conventional membrane preparation technique, and they were related to the catalytic performance of the film catalysts. Shell- and tube-type membrane reactors comprising inert polymer membranes and HPAs were designed and applied to the vapor-phase methyl tert-butyl ether (MTBE) decomposition. Simulation and experimental results revealed that polyphenylene oxide (PPO)-based membrane reactor showed the best performance, among some polymer membranes examined. Selective removal of methanol through the polymer membrane inhibited the unfavorable reverse reaction (MTBE synthesis), and at the same time accelerated the MTBE decomposition. Shell- and tube-type catalytic membrane reactors (CMRs) utilizing HPA-polymer composite catalytic membranes were also designed for the vapor-phase MTBE decomposition. Experimental results showed that HPA-polymer composite catalytic membranes not only showed catalytic reactivity for the reaction, but also were perm-selective for methanol with respect to isobutene and MTBE. It has been demonstrated that HPA-polymer composite catalytic membranes have potential application in a membrane reactor for the MTBE decomposition.

Experimental Study of the Liquid-Phase Simultaneous Syntheses of Methyl tert-Butyl Ether (MTBE) and tert-Butyl Alcohol (TBA)

Equilibrium constants for the simultaneous liquid-phase syntheses of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) were determined experimentally at 1.6 MPa in the temperature range 313−353 K using initial water/alcohol molar ratios ranging from 0 to 0.7. Experiments were performed in a batch reactor, the initial molar ratio of alcohol/isobutylene was varied from 0.5 to 2. To reach equilibrium, the macroporous sulfonic acid resin CT-275 was used as the catalyst. TBA synthesis reached chemical equilibrium faster than MTBE synthesis. The thermodynamic equilibrium constants and the enthalpy, free energy, and entropy changes of both reactions are reported as functions of temperature. Both systems behave nonideally, and the equilibrium constants were found to agree with those determined separately and reported in the literature. At 298.16 K, the standard molar enthalpy changes are −33.9 ± 4.6 kJ/mol for MTBE synthesis and −38.4 ± 3.4 kJ/mol for TBA synthesis, and the results are compared with literature data.

Etherification on Zeolites: MTBE synthesis

Although the use of methyl-tert butyl ether (MTBE) in reformulated gasoline has raised concerns due to its detection in ground water and has led to its gradual phase out in parts of the United States, the use of heavier ethers in gasoline in the future is possible. The synthesis of MTBE provides us with an insight into etherification reactions in general. This article reviews the extensive findings over the past 15 years on the application of acidic zeolites as alternative catalysts for etherification reactions and, in particular, MTBE synthesis, and compares the results with those of the commercially used ion-exchange resins. Although the resin catalysts are very active, they have some significant drawbacks (i.e., thermal fragility, sensitivity to methanol/isobutene ratios, and corrosive/disposal problems). Zeolites have been considered to be potential alternative catalysts for MTBE synthesis due to their excellent properties such as high thermal stability and modifiable acidity. The impact of various zeolite parameters, such as Si/Al ratio, type of zeolite, and the presence of extra-lattice Al, on activity is explored. Although the specific activities of most zeolites have been found to be too low to compete at low temperatures required to avoid thermodynamic limitations, H-beta zeolite has been found to be as active as the current commercial resin catalysts being used for MTBE synthesis. In addition, all zeolites studied have been found to have high selectivities to MTBE and low sensitivities to methanol/isobutene molar ratio, permitting the use of the stoichiometric reactant ratio. Application of zeolites for the synthesis of higher ethers is suggested.

Design of H 3PW 12O 40–PPO (polyphenylene oxide) composite catalytic membrane reactor and its performance in the vapor-phase MTBE (methyl tert-butyl ether) decomposition

Experimental studies on the design of shell- and tube-type heteropolyacid (HPA)-polymer composite catalytic membrane reactors (CMR) and their applications to the vapor-phase decomposition of methyl tert-butyl ether (MTBE) were reported. H 3PW 12O 40 (PW) was used as a catalyst for the reaction, and polyphenylene oxide (PPO) was used as a membrane material. It was found that the single-phase (PW-PPO/Al 2O 3, type-1) and the composite (PW-PPO/PPO/Al 2O 3, type-2) catalytic membranes not only showed catalytic reactivity for the reaction, but also were perm-selective for methanol with respect to isobutene and MTBE. The selective removal of methanol through the catalytic membrane inhibited the unfavorable reverse reaction (MTBE synthesis), and at the same time accelerated the MTBE decomposition reaction. The PW-PPO/PPO/Al 2O 3 CMR showed a superior performance compared to the PW-PPO/Al 2O 3 CMR. The enhanced performance of PW-PPO/PPO/Al 2O 3 CMR was attributed to the intrinsic perm-selective capabilities of the PW-PPO catalytic membrane and the sub-layered PPO membrane. The PW-PPO/PPO/Al 2O 3 catalytic membrane with high PW loading was less perm-selective than that with low level of PW loading. Although the PW-PPO catalytic layer itself had a lower intrinsic activity than the bulk PW catalyst in a normal reactor, PW-PPO/PPO/Al 2O 3 catalytic membrane could be utilized in a membrane reactor to achieve higher MTBE conversions than equilibrium values by means of chemical equilibrium shift at high cut-off.

Mixed-Integer Nonlinear Programming Optimization of Reactive Distillation Processes

The paper presents a conceptual method for the design of optimized processes of reactive distillation. The first part of the paper deals with the thermodynamic fundamentals of reactive distillation. Their knowledge is an indispensable prerequisite for the design of an appropriate superstructure for a given system. The second part outlines the strategy for the development of optimized processes by mixed-integer nonlinear programming (MINLP) on the basis of this superstructure. The objective function applied is the annualized total costs that contain both the investment and the operating costs. In the third part, finally, the effectiveness of the proposed method is demonstrated by two important examples of industrial reactive distillation processes, that is, the synthesis of methyl tert-butyl ether and of methylacetate.

Development of a dynamic nonequilibrium cell model for reactive distillation tray columns

In this paper we develop a nonequilibrium (NEQ) cell model to describe the dynamic operation of reactive distillation (RD) tray columns. The features of our model are: (1) use of the Maxwell–Stefan equations for describing mass transfer between fluid phases, (2) chemical reactions are assumed to take place only in the liquid phase, (3) coupling between mass transfer and chemical reactions within the diffusion layer is accounted for, and (4) the use of multiple well-mixed cells in the liquid and vapour flow directions accounts for staging in either fluid phase. When the chemical reactions are suppressed, our model describes the dynamic behaviour of conventional distillation columns. We demonstrate the utility of the dynamic NEQ cell model by means of three case studies: (1) metathesis of 2-propene in an RD column, (2) distillation of methanol– iso-propanol–water, and (3) synthesis of methyl tert-butyl ether (MTBE) in an RD column. For comparison purposes we have also carried out dynamic simulations using the equilibrium stage (EQ) model. These case studies help us to draw the following conclusions. The introduction of staging in the liquid and vapour phases not only influences the steady-state performance, by increasing reaction conversion and separation capability, but also has a significant influence on column dynamics. With multiple cells per stage the column dynamics becomes much more sensitive to perturbations. Furthermore, we show that even when the NEQ cell model and EQ stage model exhibit almost identical steady-state characteristics, the dynamic responses of an RD column could even be qualitatively different. When operating close to the distillation boundary for nonreactive, conventional, distillation, small disturbances in feed compositions can lead to completely different product compositions.

Synthesis of MTBE in zeolite membrane reactors

A zeolite membrane was employed to selectively remove water from the reaction atmosphere during the gas-phase synthesis of methyl- tert-butyl ether (MTBE) from tert-butanol and methanol. This reaction was carried out over a bed of Amberlyst™ 15 catalyst packed on the inside of a zeolite tubular membrane. The results obtained with different hydrophilic membranes (mordenite or NaA zeolite) are presented. Prior to reaction, the zeolite membranes were characterized by measuring their performance in the separation of the equilibrium mixture containing water, methanol, tert-butanol, MTBE and isobutene. The results obtained with zeolite membrane reactors (ZMR) were compared with those of a fixed bed reactor (FBR) under the same operating conditions. MTBE yields obtained with the ZMR at 334 K reached 67.6%, under conditions where the equilibrium value without product removal (FBR) would be 60.9%.