enhancement of dme production in an optimized membrane isothermal fixed-bed reactor

INTERNATIONAL JOURNAL OF CHEMICAL

REACTOR ENGINEERING

Volume 9 2011 Article A74

Enhancement of DME Production in anOptimized Membrane Isothermal

Fixed-Bed Reactor

Mohammad Farsi∗ Abdolhossein Jahanmiri†

∗Shiraz University, [email protected]†Shiraz University, [email protected]

ISSN 1542-6580DOI: 10.1515/1542-6580.2296Copyright c©2011 De Gruyter. All rights reserved.

Brought to you by | California State University Madden Library FresnoAuthenticated | 129.8.242.67

Download Date | 5/27/14 12:47 PM

Enhancement of DME Production in an OptimizedMembrane Isothermal Fixed-Bed Reactor∗

Mohammad Farsi and Abdolhossein Jahanmiri

Abstract

Dimethyl ether is a colorless gas at the ambient condition that is easily lique-fied under light pressure. Currently, DME as a green fuel has been suggested asone of the most promising candidates for substitution of LPG and diesel fuel. Inthis paper, a water cooled membrane fixed bed reactor is proposed and modeledheterogeneously for large scale production of DME from methanol dehydration.The proposed reactor is modeled one-dimensionally based on mass and energyconservation laws at steady state condition. Also, the efficacy of the proposedmembrane reactor is investigated and the results of the proposed reactor are com-pared with an isothermal and commercial adiabatic reactor. The simulation re-sults of the proposed membrane reactor indicate that the methanol conversion isimproved about 6.2 percent compared to the conventional industrial reactor. Also,water vapor removal from reaction zone in the membrane reactor yields lowerwater concentration over the catalyst pellets and higher quality of outlet product.These can lead to higher catalyst lifetime and lower cost in purification stage.

KEYWORDS: membrane reactor, heterogeneous model, methanol dehydration,adiabatic reactor

∗Please send correspondence to A. Jahanmiri; tel.: +?98 711 6303084; fax: +?98 711 6287294;email: [email protected].



1. Introduction Recently, DME as a proper and green fuel has received high attention due to global environment pollution and energy supply problem. It can be produced from variety of feed stock such as natural gas, crude oil, residual oil, coal, waste products and biomass (Arcoumanis et al., 2008). It is useful for a variety of application such as LPG substitute, transportation fuel, chemical feedstock and fuel cell (Ng et al., 1999). However, there have been attempts to develop the low cost technology to synthesize DME from syngas, but, at present DME produced from pure methanol using acidic porous catalysts as indirect synthetic method in industrial scale (Lu et al., 2004). Figure 1 shows the schematic diagram of a conventional adiabatic methanol dehydration reactor. In the conventional adiabatic reactor, the catalyst is packed in the reactor. In a heat exchanger, the heat of product stream is used to preheat the feed stream.

Figure 1, Schematic diagram of a traditional adiabatic DME reactor

There are a few articles in the literature that discuss modelling of catalytic packed bed reactors for DME production from pure methanol. Berćić and Levec (1993) modelled catalytic dehydration of methanol in a pilot scale unit at steady state condition. Predicted methanol conversion profile by this model was compared to those experimentally measured in a pilot reactor and shown intraparticle mass transport is the rate controlling step. Nasehi et al. (2006) modelled DME synthesis in a traditional adiabatic fixed bed reactor at steady state condition. They showed that the difference between one-dimensional and two-dimensional modelling is negligible. Farsi et al. (2010) proposed an optimized isothermal reactor for large scale production of DME from methanol. They modelled and optimized DME reactor at steady state condition and investigated efficiency of the isothermal reactor. The results showed that the isothermal reactor is more efficient than traditional adiabatic reactor. Figure 2 shows the schematic

Pure DME

Product

Methanol from Storage To Distillation Unit

1Farsi and Jahanmiri: DME Production Using Membrane Reactor



diagram of an isothermal DME reactor. Moradi et al. (2007) studied DME synthesis from synthesis gas in a slurry reactor experimentally and determined the optimum operating conditions of DME reactor.

Figure 2, Schematic diagram of an isothermal DME reactor

Fazlollahnejad et al. (2009) investigated methanol dehydration in a bench scale adiabatic fixed bed reactor, experimentally. The reactor was packed with 1.5 mm γ-Al2O3 pellets as catalyst and operated at atmospheric pressure. They investigated the effects of weight hourly space velocity and temperature on methanol conversion. Omata et al. (2003) studied DME production from syngas in a temperature gradient reactor for overcoming both the equilibrium limit of the reaction at high temperature and low activity of the catalyst at low temperature. Then, they optimized the reactor for higher CO conversion by combined genetic algorithm and neural network.

The application of membrane reactors has attracted much attention in the recent year (Kikuchi, 1995, Lina et al., 1998). Simultaneous occurrence of reaction and separation in a membrane reactor leads to lower cost in the separation stage compared to conventional reactors. In addition, by removing some product components from the reaction medium in a membrane reactor, constraints of thermodynamic equilibrium can be overcome towards higher conversion. Removal of a product increases the residence time for a given volume of the reactor and drives equilibrium-limited reactions towards completion. Membrane separation has been proposed to improve the performance of conventional fixed bed reactors used in the steam reforming process (Shu et al., 1994, Uemiya et al., 1991). Rahimpour and Lotfinejad modelled a membrane fixed bed reactor for methanol production from syngas at steady state condition (Rahimpour and Lotfinejad, 2007). They investigated enhancement of methanol production in a membrane reactor and showed that the methanol production

Product

Pure DME

Water

Vapor

To Distillation UnitMethanol

from Storage

2 International Journal of Chemical Reactor Engineering Vol. 9 [2011], Article A74



increased using membrane. Khassin et al. (2005) used permeable composite monolith membranes for the Fischer–Tropsch synthesis.

In this study a membrane fixed bed reactor is proposed for large scale DME production from methanol dehydration. In the proposed reactor, water vapor generated by dehydration of methanol is selectively removed from the reaction zone and equilibrium conversion is increased. Also, this leads to increase catalyst life time and lower cost of downstream separation and purification of the products. Hydrophilic membranes such as zeolite and silica are developed for water separation from organic mixtures. Lee et al. (2006) utilized water-selective alumina-silica composite membranes for design of a dehydration membrane reactor for DME synthesis from methanol. Also, Sea and Lee (2006) carried out experimental studies on a membrane fixed-bed reactor for methanol dehydration. They proved the feasibility of using ceramic membranes for synthesis of DME from methanol. The main objective of this work is modelling and simulation of the proposed membrane reactor for DME synthesis from methanol, and comparison the performance of the proposed reactor with conventional reactor. The diffusion of water vapor through the membrane layer from the reaction zone to the shell side (membrane section) makes it possible to promote the equilibrium conversion of methanol. To verify the accuracy of the considered model and assumptions, results of steady state simulation for adiabatic reactor are compared with the design data of Petrochemical Zagros Complex. Also, the optimal temperature of boiling water in cooling section in the proposed membrane reactor is computed using algorithm genetic. 2. Reaction scheme and kinetics The reaction of DME synthesis is mainly dehydration of methanol that is exothermic and reversible. In the current work, the rate expression has been selected from Berćić and Levec (1992).

kJ/mol -23.4HOH OCHCH OH2CH 2333 (1) The following reaction rate equation for methanol dehydration, r, is used:

4OHOH

.5

OHCHOHCH

eq

OHOHCOHCH

2OHCH

2233

262

33

CKCK21

KCC

Ck.Kr

2

(2)

where the reaction equilibrium constant, Keq is as follows:




T103.5 T101.23 T101.33T

31380.86 logTKln 10253

eq (3)

k1, OHCHK3

and OHK2

are, respectively, the reaction rate constant and the

adsorption equilibrium constant for methanol and water vapor that are tabulated in Table 1. Commercially, γ-Al2O3 catalyst is used in methanol dehydration reaction.

Table1, reaction rate constant and the adsorption equilibrium constant

)RT/Eexp(Ak A E

k1 3.7 × 1010 105000

OHCHK3 7.9 × 10-4 -70500

OHK2 0.84 × 10-1 -41100

3. Mathematical model of reactor

Figure 3 shows a schematic diagram of the proposed isothermal membrane fixed bed reactor.

Figure 3, Schematic diagram of the proposed membrane fixed-bed reactor

A one-dimensional heterogeneous model based on mass and energy conservation laws has been developed for this reactor. In this model the following assumptions are used:

The reactor is operated at steady state conditions. Radial dispersion of mass and energy is negligible (L D-1 > 100). The axial diffusion of mass and heat are negligible due to high gas velocity. The catalyst slice is assumed lumped body (Biot number less than 0.1).

Shell side

Shell side

Reaction side

CH3OH

Water

Sweep Gas

Vapor

CH3OHDMEH2O

H2O

H2O




Heat loss to surrounding is neglected. Methanol and DME permeation through membrane layer is negligible. Ideal gas law is considered in gas phase calculation. Subject to these assumptions, the mass and energy balances for gas phase in the reaction zone are expressed by:

iR

Rsiivgi

ig Q

A

rCCak

dz

dCu

2 (4)

WWRR

W

mmRR

Rpi

T

T iR

Rsvfpggg

TTUA

r

TTUA

rdTCQ

A

rTTah

dz

dTCu

2

2 2 1

0

(5)

The mass and energy balances for solid phase in the reaction zone are expressed by:

siivgiBi CCakrρη

(6)

TTahΔHrρη svfBi (7)

The mass and energy balances for the membrane tube are as the following,

im

Rim Q

A

r

dz

dCu

2 (8)

mRWm

Rpi

T

T im

Rpmmm TTU

A

rdTCQ

A

r

dz

dTCu

2 2 1

0

(9)

In above equations η is the effectiveness factor which is defined as actual reaction rate per particle to theoretical reaction rate in absence of internal mass transfer that could be expressed as follow.

surfacep

p

r.V

r dVη (10)




This parameter is calculated from dusty gas model along the reactor. The specifications of an industrial adiabatic fixed bed reactor are used in the proposed membrane reactor. The feed specifications and catalyst characteristics of a conventional reactor is presented in Table 2.

Table 2, Specification of an industrial adiabatic fixed bed reactor

Parameter Value

Gas phase

Feed composition (mole fraction)

CH3OH 0.94

DME 0.05

H2O 0.01

Total molar flow rate (kmol hr-1) 5600

Inlet temperature (K) 533

Inlet pressure (bar) 18.18

Catalyst particle

Particle diameter (m) 0.3175×10-2

Specific surface area (m2 m-3) 673

Reactor dimension

Reactor diameter (m) 4

Reactor length (m) 8

3.1. Membrane model

Membrane reactors combine reaction with separation to increase conversion. One of the reaction products is removed from the reactor through the membrane layer, forcing the equilibrium to the right, so that more of product is produced. As a solution to overcome the thermodynamic limitations, DME reactor can be devised by perm-selective membrane layer for H2O removal that shifts thermodynamic equilibrium in a favourable direction. In this study, the tube wall of reactor is assumed to be constructed from a water-selective alumina-silica composite membrane. This type of membrane is usually permeable to water molecules. Lee et al. (2006) proposed a composite membrane with permeability of 1.14×10-7 mol m-2 s-1 Pa-1 and a water/methanol selectivity of 8.4 at a permeation temperature of 250°C. Equation 11 is used for membrane flux modelling:




miiii PPπQ (11)

where π, Pi and Pm

i are the overall membrane permeance, the partial pressure water vapor in the reaction zone and the permeation side, respectively. 3.2. Auxiliary correlations To complete the simulation, the auxiliary correlations should be considered. In the heterogeneous model, due to transfer phenomena, proper correlations for estimation of heat and mass transfer between two phases, physical properties of chemical species and overall heat transfer coefficient between shell and tube sides should be considered. The correlation used for prediction of mass transfer coefficient between gas and solid phases is as follows (Cussler, 1984):

g.

i.

gi uScRe1.17k 670420 (12)

The correlations used for prediction of overall heat transfer coefficient and heat transfer coefficient between gas phase and reactor wall is as follows (smith, 1980):

outerouter

inner

wall

innerouterinner

inner h

1

A

A

KL

DDlnA

h

1

U

1

2

)/(

(13)

407.0

pg

2/3

p

gp

du

ε

0.458

k

μC

μρC

h (14)

4. Numerical solution The governing equations combined with the kinetic expressions and auxiliary correlations comprise nonlinear algebraic, ordinary differential equations. This set of ordinary differential equations is solved with 4th order Runge-Kutta method. 120 nodes are considered along the reactor which was small enough for the required accuracy. The results of node k are to be used as inlet conditions for the next node (k+1). At the end of this procedure it is possible to plot the concentration of components and temperature versus reactor length.




5. Results and discussions

The mathematical model of system that is a set of ordinary differential equations is solved numerically at steady state condition. The model of methanol dehydration is validated against a conventional adiabatic reactor under design specifications and input data listed in Table 2. First, the conventional reactor is modelled heterogeneously based on mass and energy conservation laws at steady state condition. It is observed that the simulation results of conventional reactor have a good agreement with the industrial plant data. The comparison between steady state simulation results and plant data is shown in Table 3. The plant data used for evaluation has been taken from Zagros Petrochemical Complex in Iran.

Table 3, Comparison simulation results and plant data for the adiabatic reactor Simulation result Plant data A.E

DME molar flow rate (kmol hr-1) 2457 2506 1.95%

MeOH molar flow rate (kmol hr-1) 940.6 937.7 0.31%

Temperature (oC) 652.2 644 1.27%

In order to establish a reference point for modelling of the proposed membrane reactor a “base case” is considered. The inlet composition of the membrane reactor is typical of industrial DME process. The base case for the methanol dehydration is similar to those used by Farsi et al. (2010). The characteristics and design specifications of the proposed reactor is presented in Table 4.

Table 4, Characteristics of the proposed membrane reactor

Parameter Value

Inner tube diameter of reaction side (m) 0.09

Outer tube diameter of water side (m) 0.0254

Reactor length (m) 8

Tube number 2000

Generally, there is an optimal temperature for reversible exothermic reactions, which maximize production rate. Considering optimal temperature profile along the reactor results the highest conversion. In this work the obtained set of nonlinear differential are solved and the optimal temperature for saturated




water in cooling section is calculated to maximize outlet methanol conversion using genetic algorithm. The maximum DME production is attainable by applying this temperature in the cooling section. The optimal temperature for saturated water in cooling section of membrane reactor is calculated about 596 K. Figures 4(a) and (b) show the comparison DME mole fraction and DME mole flow rate along the membrane reactor with adiabatic and isothermal reactors. It is observed that there is considerable difference between DME mole fraction profile in the membrane reactor with adiabatic and isothermal reactors under steady state conditions. The difference is much higher for the upper section of the reactor which is due to water vapor removal. This novel configuration can increase DME mole fraction at reactor outlet about 25% and 22.2 % compared with adiabatic and isothermal reactor, respectively. In this configuration, simultaneous occurrence of methanol dehydration reaction and H2O removal in the reaction zone leads to higher outlet DME mole fraction and lower cost in the purification stage compared to conventional and isothermal reactors. Also, by H2O removal from the reaction section in the membrane reactor, constraints of thermodynamic equilibrium can be overcome towards higher conversion. Additionally, decrease water vapor mole fraction leads to increase catalyst life time.

0 2 4 6 80.05

0.15

0.25

0.35

0.45

0.55

Length (m)

DM

E m

ol f

ract

ion

Adiabatic reactorIsothermal reactorMembrane reactor

(a)

Figure 4(a), DME mole fraction along the membrane,

adiabatic and isothermal reactors




0 2 4 6 80

500

1000

1500

2000

2500

3000

Length (m)

DM

E m

ol f

low

(km

ol h

r -1)


(b)

Figure 4(b), DME mole flow rate along the membrane, adiabatic and isothermal reactors

This configuration can increase the DME mole flow rate at the reactor outlet about 5.2 % compared with adiabatic reactor. Figure 5 shows the axial temperature profile inside the reaction zone in the proposed membrane, adiabatic and isothermal reactors. In the adiabatic reactor, the temperature increases to equilibrium temperature (652 K) and maintains constant. The temperature of reaction zone in the proposed membrane reactor is lower than of the adiabatic and higher than isothermal reactors. At the entrance of the membrane reactor, temperature increases and a hot spot develop as demonstrated in Figure 5 and then decreases smoothly to about 496 K. According to Le Châtelier’s principle, temperature reduction in the second half of the proposed reactor leads to shift the methanol dehydration reaction in the direction of DME production.




0 2 4 6 8520

540

560

580

600

620

640

660

Length (m)

Tem

pera

ture

(K

)


Figure 5, Temperature profile along the membrane,

adiabatic and isothermal reactors

Figure 6 shows the comparison of methanol mole flow rate along the membrane reactor with adiabatic and isothermal reactors at steady state condition. The important point as illustrated in these figures is that reaction kinetic controlling in the initial sections of reactor and in other sections, the rate of reaction has decreased to its equilibrium value and thermodynamic equilibrium is reaction controlling. Thus, by water vapor removal as a product, thermodynamic constrain shifts to the right side of the methanol dehydration reaction and consequently more methanol is consumed. In additional, by water vapor removal from reaction zone, gas velocity along the reactor decreases and consequently lower pressure drop is attainable.




0 2 4 6 8

500

1500

2500

3500

4500

5500

Length (m)

MeO

H m

ol f

low

(km

ol h

r -1)


Figures 6, Methanol flow rate along the membrane, adiabatic and isothermal reactors

Figure 7(a) shows the water vapor mole flow rate along the membrane, isothermal and conventional reactors. It is observed from this figure that water mole flow rate profile along the membrane reactor is considerably lower than isothermal and conventional adiabatic reactors. At the entrance of the membrane reactor, Water vapor mole flow rate increases and then decreases due to permeation from reaction zone through membrane layer. According to Le Châtelier’s principle, water vapor removal as a reaction product leads to shift the methanol dehydration reaction in the direction of DME production. This novel configuration can increase the DME mole flow rate about 5.25 % compared with adiabatic reactor in same feed condition. In isothermal and conventional reactors, except in initial section, thermodynamic limitation causes the same water vapor profile. Figure 7 (b) shows the water vapor mole flow along the permeation section. In the proposed membrane reactor about 900 kmol hr-1 water vapor penetrate from reaction zone to membrane section. Penetrated water vapor flux depends on water vapor pressure across the membrane layer. Water vapor permeation from reaction zone to separation side results in shifting of the dehydrogenation reaction to right and increases the DME mole fraction and its purity. While there is a difference between water vapor partial pressure in the reaction zone and permeation side, Water vapor can continuously pass from the reaction zone into the permeation side. Therefore, the water vapor mole fraction in the permeation side should increase along the reactor length.




0 2 4 6 80

500

1000

1500

2000

2500

Length (m)

Wat

er m

ol f

low

(km

ol h

r -1)


(a)

Figure 7(a), H2O flow rate along the membrane,

adiabatic and isothermal reactor

0 2 4 6 8 80

200

400

600

800

1000

Length (m)

Wat

er m

ol f

low

(k

mol

e h

r -1

)

(b)

Figure 7(b), H2O flow rate along the membrane section

The methanol conversion profile in membrane and conventional reactor

are presented in Figure 8. The methanol conversion in membrane reactor is 86.2 % that is 6.2 % higher than methanol conversion in adiabatic reactor. Also, the methanol conversion, DME and water mole flow rate in outlet stream is presented in Table 5.




0 2 4 6 80

20

40

60

80

100

Length (m)

Con

vers

ion

Proposed membrane reactorAdibatic reactor

Figure 8, Methanol conversion in membrane and conventional reactors

It is observed that the performance of the proposed membrane reactor is considerably better than the conventional adiabatic reactor. Higher methanol conversion and DME production rate due to shift thermodynamic equilibrium, higher catalyst life time and lower purification cost due to water vapor removal are major and considerable benefits of the proposed membrane reactor.

Table 5, Comparison the performance of membrane, adiabatic and isothermal reactors

Parameter Conventional Isothermal reactor Proposed reactor

Methanol conversion 81.9 % 84.7 % 87 %

Outlet H2O mole fraction 0.40 0.41 0.31

DME mole flow(kmol hr-1) 2453 2527.5 2586

Outlet DME mole fraction 0.44 0.45 0.55

6. Conclusion

In this research a membrane reactor was proposed for large scale production of DME from methanol dehydration. The tubes wall of the membrane reactor was constructed from a water vapor perm-selective alumina-silica composite. The proposed reactor represents some important improvement compared to conventional adiabatic and isothermal reactors. Higher methanol conversion and




DME production rate due to shift thermodynamic equilibrium, higher catalyst life time and lower purification cost due to water vapor removal are major benefits of the proposed reactor. In additional, by water vapor removal, gas velocity along the reactor decreases and consequently lower pressure drop is attainable. The results showed that the optimum temperature for saturated water in the cooling section is about 596 K, in the operating conditions of the base case. The simulation results for the membrane and conventional adiabatic reactors indicated that DME production rate increases about 5.25 % by the proposed configuration compared with the industrial reactor. The results proved that DME synthesis in the proposed membrane reactor is feasible and beneficial. 7. Nomenclature av Specific surface area of catalyst pellet (m2 m-3)

A Cross section area (m2)

Ci Molar concentration of component i (mol m-3)

Cp Specific heat of the gas at constant pressure (J mol-1)

D Tube diameter (m)

dp Catalyst diameter (m)

hf Gas-solid heat transfer coefficient (W m-2 K-1)

hi Heat transfer coefficient between reaction side and reactor wall (W m-2 K-1)

ho Heat transfer coefficient between cooling side and reactor wall (W m-2 K-1)

ΔH Heat of reaction (J mol-1)

k Rate constant of dehydrogenation reaction (mol m-3 Pa-1 s-1)

kg Mass transfer coefficient for component i (m s-1)

Keq Reaction equilibrium constant for methanol dehydration (mol m-3)

Kw Thermal conductivity of reactor wall (W m-1 K-1)

L Reactor length (m)

Pi Partial pressure of component i (Pa)

Q Membrane flux (mol m-2 Pa-1 s-1)

r Rate of reaction for DME synthesis (mol kg-1 s-1)

R Radius (m)

Re Reynolds number




Sci Schmidt number of component i

T Temperature (K)

Tshell Shell side temperature (K)

u velocity of fluid phase (m s-1)

U Overall heat transfer coefficient (W m-2 K-1)

V Volume (m3)

z Axial reactor coordinate (m)

Greek letters μ Viscosity of fluid phase (kg m-1 s-1)

ρ Density of fluid phase (kg m-3)

ρb Density of catalytic bed (kg m-3)

η Effectiveness factor

π the overall membrane permeance (mol m-2 s-1)

ε Void fraction

Subscripts g In gas phase

i Chemical species

m Membrane section

R Reaction section

s At catalyst surface

w Cooling section

8. References

Arcoumanis C., Bae C., Crookes R., Kinoshita E., "The potential of dimethyl ether (DME) as an alternative fuel for compression-ignition engines: A review", Fuel, 2008, 87, 1014-1030.

Berćić G., Levec J., "Intrinsic and global reaction rate of methanol dehydration over Al2O3 pellets", Ind. Eng. Chem. Res., 1992, 31, 1035-1040.




Berćić G., Levec J., "Catalytic Dehydration of Methanol to Dimethyl Ether. Kinetic Investigation and Reactor Simulation", Ind. Eng. Chem. Res. 1993, 32, 2478-2484.

Cussler E. L., "Diffusion, Mass transfer in fluid system", 1984, Cambridge

University Press, UK. Farsi M., Jahanmiri A., Eslamlueyan R., "Modeling and Optimization of MeOH to

DME in Isothermal Fixed-bed Reactor", International Journal of Chemical Reactor Engineering, 2010, 8, Article A79.

Fazlollahnejad M., Taghizadeh M., Eliassi A., Bakeri G., "Experimental Study

and Modeling of an Adiabatic Fixed-bed Reactor for Methanol Dehydration to Dimethyl Ether", Chinese J. Chem. Eng., 2009, 17, 4, 630–634.

Khassin A. A., Sipatrov A. G., Yurieva T. M., Chermashentseva G. K., Rudina N.

A., Parmon V. N., , "Performance of a catalytic membrane reactor for the Fischer–Tropsch synthesis", Catalysis Today, 2005, 105, 362–366.

Kikuchi E., "Palladium/ceramic membranes for selective hydrogen permeation

and their application to membrane reactor", Catalysis Today, 1995, 25, 333–337

Lee K. H., Youn M. Y., Sea B., "Preparation of hydrophilic ceramic membranes

for a dehydration membrane reactor", Desalination, 2006, 191, 296–302. Lina Y. M., Leeb G. L., Rei M. H., "An integrated purification and production of

hydrogen with a palladium membrane–catalytic reactor", Catalysis Today, 1998, 44, 343–349.

Lu W. Z., Teng L. H., Xiao W. D., "Simulation and experiment study of Dimethyl

ether synthesis from syngas in a fluidized-bed reactor", Chemical Engineering Science, 2004, 59, 5455–5464.

Moradi G. R., Ghanei R., Yaripour F., "Determination of the Optimum Operating

Conditions for Direct Synthesis of Dimethyl Ether from Syngas", International Journal of Chemical Reactor Engineering, 2007, 5, Article A14.




Nasehi S. M., Eslamlueyan R., Jahanmiri A., "Simulation of DME reactor from methanol", Proceedings of the 11th chemical engineering conference, Iran, Kish Island, 2006.

Ng K. L., Chadwick D., Toseland B. A., "Kinetics and modeling of Dimethyl ether synthesis from synthesis Gas", Chemical Engineering Science, 1999, 54, 3587-3592.

Omata K., Ozaki T., Umegaki T., Watanabe Y., Nukui N., Yamada M., "Optimization of the temperature profile of a temperature gradient reactor for DME synthesis using a simple genetic algorithm assisted by a neural network: High-quality transportation fuels", Energy & fuels, 2003, 17, 4, 836-841.

Rahimpour M. R., Lotfinejad M., "Enhancement of Methanol Production in a Membrane Dual-Type Reactor", Chem. Eng. Technol., 2007, 30, 1062–1076.

Sea, B., Lee, K. H., "Synthesis of Dimethyl ether from methanol using alumina–silica membrane reactor", Desalination, 2006, 200, 689–691.

Shu J., Grandjean B. P. A., Kaliaguine S., "Methane steam reforming in asymmetric Pd–Ag and Pd–Ag/porous SS membrane reactors", Applied catalysis, 1994, 119, 305–325.

Smith J. M., "Chemical Engineering Kinetics", 1980, McGraw-Hill, New York.

Uemiya S., Sato N., Ando H., Matsuda T., Kikuchi E., "Steam reforming of methane in a hydrogen-permeable membrane reactor", Applied catalysis, 1991, 67, 223- 230.




enhancement of dme production in an optimized membrane isothermal fixed-bed reactor

Documents