TITTLE: Kinetics of Toluene alkylation with methanol catalyzed by HZSM-5,

ZM13 and MOR/ZSM-5 zeolites

NAME OF STUDENT: ALABI, WAHAB OLAIYA.

STUDENT LEVEL: Msc Chemical Engineering.

NAME OF SUPERVISOR: Prof.Sulaiman Al-Khattaf.

UNIVERSITY: King Fahd University of Petroleum and Minerals.

DATE OF SUBMISSION: 13th of Feb., 2012.

Abstract

Kinetic study of toluene alkylation with methanol was performed over pure

HZSM-5, MOR/ZSM-5(hybrid mordinite and HZSM-5), and ZM13 (composite

mixture of HZSM-5 and MCM-41 at PH 13). Experimental runs were carried out

using a fluidized bed reactor at temperatures of 300, 350 and 400 C and reaction

times of 3, 5, 7, 10, 13, 15 and 20 s. the rate of toluene methylation and toluene

disproportionation were study on the three catalyst(toluene alkylation is usually

accompanied by toluene disproportionation on acid catalyst). Based on the results

obtained, a simplified power law kinetic model consisting of three reactions was

developed to account for the overall transformation of toluene. Coke formation on

catalysts was evaluated using both reaction time and reactant conversion decay

functions. All parameters were estimated based on quasi-steady state

approximation. Estimated kinetic parameters were in good agreement with

experimental results. It was found that the order of alkylation ability of the

catalysts is; ZM13 > HZSM-5 > MOR/ZSM-5 ,while the reverse is for toluene

disproportionation (MOR/ZSM-5 > HZSM-5 > ZM13 ).Thus; alkylation of toluene

is most favorable on ZM13 due to combined effect of mesoporosity induced

through its synthetic route and acid content. Toluene/MeOH molar ratio of 1:1 is

suitable for toluene alkylation

Keywords: Toluene alkylation, disproportionation reaction, xylene, zeolite catalyst,

power law model, reaction time, reactant conversion

1

Kinetics of Toluene alkylation with methanol catalyzed by HZSM-5, ZM13

and MOR/ZSM-5 Zeolites

Introduction

Zeolites are highly amenable to industrial acid-catalyzed reactions due to their

unique properties, such as shape selectivity, high porosity, and thermal stability [1-

4]. Its favorable activity has been attributed mostly to the brnsted acid sites. The

production of xylenes by the petrochemical industry has increased over the years

due to its numerous applications. P-xylene is an important precursor to terephthalic

acid and dimethyl terephthalate, both are key components of polyethylene

terephthalate (PET) production. o-xylene is used mainly in the synthesis of

phthalic acid anhydride while m-xylene is usually oxidized to isophthalic acid.

Among the recent possible routes to xylene production is toluene

disproportionation. Nevertheless, co-formation of benzene has made this route less

viable. The study of another potential route with great economic interest is

alkylation of toluene. This route has the advantage of using methanol as the

alkylating agent which is a cheaper raw material and available in abundance [5].

The reaction mechanism of toluene methylation has been studied extensively, and

this has been summarized into two mechanistic approaches.

Attempts have also been made in the aspect of kinetic studies of toluene alkylation

reaction [6-11]. A comprehensive review showed efforts have been mainly focused

on obtaining kinetic data over archetype ZSM-5 catalysts using fixed bed reactor.

Recently, Al-Khattaf and co-workers [12-14] have reported the use of fluidized

bed reactor for different zeolite catalysts.

In the present study we examine the catalytic performance of HZSM-5,

ZM13 and hybrid MOR/ZSM-5 zeolite catalysts for toluene-methanol alkylation

reaction. Our approach involves obtaining extensive kinetic data as a function of

2

reaction conditions (both temperature and time) to estimate the kinetic parameters.

A power law kinetic model was developed to probe the kinetics of the reaction in a

fluidized bed reactor. The physico-chemical and acidic properties of the zeolite

catalysts were evaluated using analysis such as XRD, N2 adsorption, and Pyridine

FTIR (Py-IR).

Experimental Section

Catalysts Preparation

The calcined HZSM-5 with Si/Al ratio of 13.5 and surface area of 284 m2/g

was obtained from CATAL, UK. The uncalcined proton form of mordenite with

Si/Al ratio of 18.3 and surface area of 364 m2/g was obtained from Tosoh

Chemicals, Japan. The calcined form of mordenite was then physically mixed with

HZSM-5 in 1:1 ratio to form MOR/ZSM-5 catalysts. ZM13 is a composite of

HZSM-5 and MCM-41 which is obtained by the disintegration and assembly of the

former in the latter. The synthesis procedure involves disintegrating 2g of HZSM-5

using 0.7 M NaOH solution at a pH condition of 13 by gradual heating (without

stirring) at 100 oC for 24 h in the presence of CTAB (4.45%). The mixture was

cooled down and pH adjusted to 9.0 through the addition of dilute sulfuric acid

(2N). The mixture was then stirred for 24 h followed by ageing at 100 C for 24 h.

The solid product was filtered, washed thoroughly using distilled water, dried at

80oC overnight, then calcined at 550 C for 6 h to remove the surfactant. The

obtained composite was ion-exchanged thrice with 0.05M NH4NO3 solution at 80 oC for 2 h then calcined at 550oC for 2 h.

3

Catalysts Characterization

Brunauer-Emmett-Teller (BET) technique was used to determine the surface

areas of the catalyst samples. This was achieved through the N2 adsorption-

desorption isotherm using Quantachrome AUTO-SORB-1 (model # ASI-CT-8).

Adsorption measurements were carried out after the samples had been heated at

100 C for 3 h in the presence of N2 gas stream.

Structural elucidation of the catalyst samples were examined using X-ray

power diffraction (XRD). Diffraction patterns were obtained on a Bruker D8

Advance X-ray powder diffractometer equipped with a graphite monochromator

and position sensitive detector using Cu K radiation in Bragg-Brentano

geometry.The XRD result in figure 1, BET and Acidity test result ;table 1

Catalytic Testing

In a typical experiment, 0.8g of catalyst sample which has already been

crushed and sieved to ~60 m was loaded into the catalyst basket of the riser

simulator, a bench scale fluidized bed reactor invented by de Lasa [23]. Before the

actual experimental runs, the catalyst was thermally activated at 620 C for 15 min

in the presence of Ar. A liquid mixture of the feedstock (toluene and methanol)

was injected into the reactor. Two thermocouples, one located in the catalyst bed

and the other on the outer wall of the reactor were used to monitor the reaction

temperature. Typically, the temperature difference recorded is negligible. The

temperatures for the catalytic reactions are 300, 350 and 400 C for 7 different

reaction times varying from 3 - 20 s. On the other hand, the reaction pressure

changes from 1 atm at the point of injecting the feedstock to ~2.5 atm at the end of

the reaction. This increase, monitored by the pressure transducer, is due to the

vaporization of the liquid mixture and the reacting species produced. The reactor

effluent was analyzed online using Agilent GC with FID (Agilent Chromatograph

4

Model 6890N), equipped with an HP-INNOWax capillary column (Polyethylene

glycol (PEG)) (length 60 m x internal diameter 0.32 mm x film thickness 0.50

m). During the course of the investigation, a number of runs were repeated to check for reproducibility in the experiment results, which were found to be

excellent. Typical errors were in the range of 2 %.

The experimental results of the three catalysts at different temperatures and time

are shown in tables 2-4.

Kinetic Modeling

Reaction kinetic study is presented in this section, the purpose of which to

develop a simplified kinetic model for the detailed catalytic reaction. In particular,

emphasis is on the main reactions which took place during toluene alkylation with

methanol. The kinetic scheme employed therefore showed in details the main reactions as presented in scheme 1:

Scheme 1: reaction network for toluene-methanol alkylation

Similar reaction scheme have been proposed by Serra et. al. [15] when

toluene-methanol alkylation reaction was catalyzed by solid acids. For the purpose

k3k2

H2OH2O

CH3OH

Xylene

Benzene

CH3

Xylene

TMB

CH3CH3

k1

CH3

CH3

Toluene

CH3OH CH3

CH3

2

5

of developing the kinetic model, experimental data obtained for toluene/MeOH

molar ratio of 1:1 is used

Model Formulation

Power law model has been used to study the kinetics of the observed

chemical reactions. The governing equations for the riser simulator are simply

material balances for reactants and products of the chemical reaction similar to

batch reactor. In general, for each independent reacting species, the material

balance equation can be written as:

(1)

Where and are the reaction rate and mole concentration of each species in the

system, is the volume of the reactor, is the mass of the catalyst, is time in

seconds, while is the deactivation function to account for catalytic activity loss.

The rate equations for the elementary reactions can then be written as:

2 (2)

(3)

(4)

Rate constant which is a function of pre-exponential factor and activation energy

as defined by Arrhenius equation is expressed to incorporate temperature

dependence of the reaction given as:

1

1

(5)

6

Where is the pre-exponential factor of reaction i and Ei is the energy of

activation of the reaction i. is referred to as the centering temperature which is

the average of all the temperatures for the experiment. This was introduced to

reduce parameter interaction as postulated by Agarwal and Brisk [16]. Reactions

involving hydrocarbons inevitably yields coke deposit. Two catalyst deactivation

functions were investigated in this study: reaction (RT) and reactant conversion

(RC) expressed as exp [17] and exp1 [18];

where and are decay constants for their respective deactivation functions and

is the weight fraction of toluene, ().

Expressing concentrations in terms of weight fraction of each species , which

are the measurable variables from the chromatographic analysis, we have:

(6)

Where is the weight of feedstock injected into the reactor, is the

molecular weights of the species.

Based on scheme 1, rate of reaction for toluene, benzene, xylene and TMB species

can thus be written as:

2

(7)

(8)

(9)

7

(10)

Model Assumptions

Summarized below are the assumptions taken into consideration for the model

formulation:

1. The reactor operates under isothermal condition

2. Toluene diproportionation is considered to have irreversible reaction path

and taken to be second order.

3. Effectiveness factor, , is been taken to be unity. Similar assumption was

used in previous works [12-14]

4. Isomers of xylene and TMBs are grouped together for a simplistic model

evaluation.

Model Parameter Evaluation

Using non-linear regression analysis combined with fourth order Runge-

Kutta routine to numerically integrate the rate equations, the kinetic parameters for

the toluene-methanol alkylation reaction over the zeolite catalysts under study

were evaluated. The developed model provides approximate estimates of all the

kinetic parameters which are shown in tables 5 and 6. o Also, the R-squared value

of the regression is close to unity (0.99) and a parity plot of the weight fractions of

the reactive species (Figure 3) gave an excellent fit between the predicted and

experimental data, indicating the suitability of the proposed model. Extensive

studies have been reported on kinetics of toluene alkylation reaction with methanol

over ZSM-5 (modified and unmodified). In the present study, activation energy for

8

HZSM-5 has an approximate value of ~57 kJ/mol for toluene methylation reaction,

irrespective of the deactivation model employed. This value is very much

comparable with the works of previous authors as shown in Table 8. Vinek and

Lercher [19] reported an apparent activation energy of 50 55 kJ/mol for toluene

alkylation with methanol on H-ZSM-5, a value of 68 kJ/mol was reported by Rabiu

and Al-Khattaf [12] and most recently, Odedairo et al [13] estimated a value of 47

kJ/mol for similar reaction on ZSM-5. For a modified ZSM-5 with magnesium,

Sotelo et al. [20] obtained apparent activation energy of 60 kJ/mol. In general,

activation energy for alkylation of toluene with methanol reported by several

authors has been summarized by Mirth et. al. [21] to be typically in the range of 50

90 kJ/mol.

Both for ZM13 and MOR/ZSM-5, the apparent energy barriers for the

reactions are lower than that on HZSM-5. It has been established that apparent

activation energy is equivalent to half the summation of both intrinsic and

diffusion activation energies [22]. Intrinsic activation energy however is related to

acidity of the catalyst; high acid catalysts have low intrinsic energy. HZSM-5 is a

two-dimensional channel structure defined by 10 member ring, with a medium

pore of ~6 . This creates a steric effect on large molecules which imposes

diffusional constraint. We can therefore conclude that, the pore structure of

HZSM-5 plays more significant role in its reactivity despite having acid sites

(brnsted) of higher concentration and strength than ZM13. Methylation of toluene

on ZM13 has apparent activation energy of 15 kJ/mol while 21 kJ/mol is calculated

for MOR/ZSM-5 using time-on-stream catalyst deactivation model (table 5). On

the other hand, toluene disproportionation overcomes energy barrier of 20.3 kJ/mol

and 13.1 kJ/mol on ZM13 and MOR/ZSM-5 respectively. Similar activation

energies for both reactions have been estimated with marginal difference (table 6)

9

when catalyst deactivation by reactant conversion model is used. These kinetic

parameter results are quite similar to the experimental observation in which

methylation of toluene is best favored on ZM13. Due to aforementioned diffusion

limitation which has been assumed to influence the apparent activation energy of

HZSM-5, the order of toluene methylation, ZM13 > MOR/ZSM-5 > HZSM-5 and

toluene disproportionation, MOR/ZSM-5 > ZM13 > HZSM-5 follows a different

pattern from the one proposed earlier. Xylene methylation on HZSM-5 has high

activation energy of 70 kJ/mol (RT model). This further confirms the effect of

diffusion limitation of large molecules within its pores. TMBs are more bulky

molecules, larger than both xylene and toluene, hence higher barrier to overcome.

Values of 15.2 kJ/mol and 17.8 kJ/mol are estimated respectively for MOR/ZSM-5

and ZM13, both possessing larger pores.

Conclusion

Detailed kinetic data were obtained employing a fluidized bed reactor (riser

simulator) for toluene/MeOH molar ratio 1:1. Power law model was used to

evaluate the kinetic parameters based on time-on-stream (TOS) and reactant

conversion (RC) catalyst decay function. Similar results were obtained for both

and deactivation due to coke deposit was accounted to be fairly minimal, but not

negligible. The apparent activation energies of toluene methylation and

disproportionation reactions on HZSM-5 have higher values compared to ZM13

and MOR/ZSM-5. The order of activation energies for toluene methylation is

HZSM-5 (56.1 kJ/mol) > MOR/ZSM-5 (20.8 kJ/mol) > ZM13 (14.6 kJ/mol)

whereas the order of toluene disproportionation is HZSM-5 (54.8) > ZM13 (20.3)

> MOR/ZSM-5 (13.1) References

(1) Davis, M. E. Acc. Chem. Res. 1993, 26, 111115.

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(2) Corma, A.; Martinez, A. Catal. Rev.Sci. Eng. 1993, 35, 483570.

(3) De Vos, D. E.; Dams, M.; Sels, B. F.; Jacobs, P. A. Chem. Rev.2002, 102, 36153640.

(4) Sartori, G.; Maggi, R. Chem. Rev. 2006, 106, 10771104. Use of solid catalysts in friedel-

crafts acylation reactions.

(5) A.B. Halgeri, Bull. Catal. Soc. India 2 (2003) 184193.

(6) Wei, J. A mathematical theory of enhanced para-xylene selectivity in molecular sieve catalysts. J. Catal. 1982, 76, 433. (7) Hashimoto, K., Masuda, T., Kawase, M., Karge, H. G., Weitkamp, J., Eds. Zeolites as

Catalysts, Sorbents and Detergent Builders. Stud. Surf. Sci. Catal. 1989, 46, 485.

(8) Young, L. B.; Butter, S. A.; Kaeding, W. W. Selectivity in xylene isomerization, toluene-

methanol alkylation and toluene disproportionation over ZSM-5 zeolite catalysts. J. Catal. 1982,

76, 418.

(9) Kaeding, W. W.; Chu, C.; Young, L. B.; Weinstein, B.; Butter, S. A. Selective Alkylation of

Toluene with Methanol to Produce para-Xylene. J. Catal. 1981, 67, 159.

(10) Bhat, Y. S.; Halgeri, A. B.; Prasada Rao, T. S. R. Kinetics of Toluene Alkylation with

Methanol on H-ZSM-8 Zeolite Catalyst. Ind. Eng. Chem. Res. 1989, 28, 890-894

(11) Ramakrishna, M.; Subhash, B.; Musti, S. R. Kinetics of Deactivation of Methylation of

Toluene over H-ZSM-5 and Hydrogen Mordenite Catalyst. Ind. Eng. Chem. Res. 1991, 30, 281-

(12). Al-Khattaf S, Rabiu S, Tukur NM, Alnaizy R (2008) Chem Eng J 139:622

(13) Kinetics of Toluene Methylation over ZSM-5 Catalyst in a Riser Simulator, S. Rabiu and S.

Al-Khattaf, Ind. Eng. Chem. Res. 2008, 47, 39-47

(14) Toluene Disproportionation and Methylation over Zeolites TNU-9, SSZ-33, ZSM-5, and

Mordenite Using Different Reactor Systems, T. Odedairo, R.J. Balasamy, and S. Al-Khattaf, Ind.

Eng. Chem. Res. 2011, 50, 31693183.

(15) Serra, J.M.; Corma, A.; Farrusseng, D.; Baumes, L.; Mirodatos, C.; Flego, C.; Perego, C., Catal. Today, 2003, 81, 425 436.

(16) Agarwal, A. K; Brisk, M. L.; Agarwal, A. K; Brisk, M. L. Ind. Eng. Chem. Process Des. Dev. 1985, 24, 203

(17) Weekman, V. W. Ind. Eng. Chem. Process Des. Dev. 1968, 7, 90-95.

(18) Al-Khattaf, S.S.; de Lasa, H.I. Ind. Eng. Chem. Res, 2001, 40, 5398.

(19) Vinek, H.; Lercher, J. J. Mol. Catal. 1991, 64, 2339.

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(20) Sotelo, J. L.; Uguina, M. A.; Valverde, J. L.; Serrano, D. P. Ind. Eng. Chem. Res. 1993, 32, 2548-2554.

(21) Mirth, G.; Lercher, J. A. J. Catal.1991, 132, 244252

(22) Vinek, H.; Lercher, J. J. Mol. Catal. 1991, 64, 2339.

(23) de Lasa, H. I. Riser simulator for catalytic cracking studies. U.S. Patent 5, 1991, 102, 628.

List of Figures

Figure 1: XRD pattern of zeolites: a) HZSM-5, b) MOR/ZSM-5, c) ZM13

List of Figures

Figure 1: XRD pattern of zeolites: a) HZSM-5, b) MOR/ZSM-5, c) ZM13

Figure 2: Catalytic activity of A) HZSM-5, b) MOR/ZSM-5, c) ZM13. reaction

conditions: temperature = 300 400 C, reaction time = 3 20 s,

toluene/MeOH molar ratio = 1:1

Figure 3: Parity plot of toluene conversion for the three zeolite samples

List of Tables

Table 1: Physicochemical and acid properties of the three zeolites samples

Table 2: Product distribution of toluene alkylation with methanol

(toluene/MeOH ratio = 1:1) on HZSM-5

Table 3: Product distribution of toluene alkylation with methanol

(toluene/MeOH ratio = 1:1) on MOR/ZSM-5

Table 4: Product distribution of toluene alkylation with methanol

(toluene/MeOH ratio = 1:1) on ZM13

12

Table 5: Estimated kinetic parameters for toluene-methanol (1:1) reaction over

HZSM-5, MOR/ZSM-5 and ZM13 catalysts using TOS model

Table 6: Estimated kinetic parameters for toluene-methanol (1:1) reaction over

HZSM-5, MOR/ZSM-5 and ZM13 catalysts using RC model

Table 7: Activation energies for toluene alkylation with methanol reported in

literatures

Figure 1: XRD pattern of zeolites: a) HZSM-5, b) MOR/ZSM-5, c) ZM13

1 0 2 0 3 0 4 0 5 0 6 0 7 0

Inte

nsity

(a.u

.)

2 T h e ta

(a )

(b )

(c )

13

Figure 2: Catalytic activity of A) HZSM-5, b) MOR/ZSM-5, c) ZM13. Reaction conditions:

temperature = 300 400 C, reaction time = 3 20 s, toluene/MeOH molar ratio = 1:1

2 4 6 8 10 12 14 16 18 20 220

4

8

12

16

20

24

28

32

36

2 4 6 8 10 12 14 16 18 20 22

5

10

15

20

25

30

35

40

45

2 4 6 8 10 12 14 16 18 20 220

4

8

12

16

20

24

28

32

36

3000C3500C4000C

Tolu

ene

conv

ersi

on /

%

Reaction time / s

A B

3000C3500C4000C

Reaction time / s

C

3000C3500C4000C

Tolu

ene

conv

ersi

on /

%

Reaction time / s

14

Figure 3: Parity plot of toluene conversion for the three zeolite samples

0 10 20 30 400

10

20

30

40

Pred

icte

d

Experimental

15

Table 1: Physicochemical and acid properties of the three zeolites samples

Samples

Si/Al

ratio

Surface

Area (m2/g)

Brnsted acid sites

(mmol/g)

Lewis acid sites

(mmol/g) L/B ratio

(400 C) 150 C 400 C 150 C 400 C

ZSM-5 13.5 284 0.4497 0.3296 0.2093 0.1305 0.40

MOR/ZSM-5 22 364 0.5381 0.4278 0.0447 0.0321 0.08

ZM13 12 468 0.3541 0.2658 0.2380 0.1448 0.54

16

Table 2: Product distribution of toluene alkylation with methanol (toluene/MeOH ratio = 1:1) on

HZSM-5

Reaction time (s)

Toluene Conv. (%)

Yield (%) Gas Benzene p-

xylene m-xylene o-

xylene Total xylene

aTMBs

300 C

3 1.07 0.38 0.34 0.82 0.78 0.30 1.90 0.28 5 2.18 0.40 0.65 1.24 1.70 0.52 2.46 0.32 7 3.05 1.28 0.83 1.82 2.14 0.81 4.77 0.41 10 3.97 1.40 0.86 2.16 2.46 0.96 5.58 0.45 13 6.54 1.59 1.15 2.57 3.12 1.22 6.91 0.52 15 7.85 1.74 1.27 2.76 3.48 1.36 7.60 0.55 20 9.65 1.85 1.37 3.05 4.00 1.58 8.63 0.63

350 C

3 2.35 0.95 0.75 1.28 1.73 0.65 3.66 0.36 5 5.48 1.38 1.07 1.87 2.64 1.00 5.51 0.45 7 8.84 1.75 1.60 2.36 3.58 1.39 7.33 0.61 10 12.92 2.17 1.94 2.94 4.55 1.77 9.26 0.74 13 15.76 2.48 2.32 3.37 5.39 2.13 10.89 0.88 15 18.30 2.76 2.50 3.73 6.07 2.42 12.22 0.96 20 21.67 3.14 3.34 4.05 6.98 2.83 13.86 1.27

400 C

3 9.76 1.74 1.78 2.11 3.51 1.38 7.00 0.52 5 15.73 2.54 2.51 3.13 5.38 2.11 10.62 0.68 7 21.09 3.20 3.01 3.86 6.88 2.69 13.43 0.76 10 25.15 3.45 3.82 4.22 8.07 3.29 15.58 0.99 13 28.92 3.66 4.31 4.82 9.32 3.83 17.97 1.11 15 29.63 3.78 4.73 4.90 9.75 4.08 18.73 1.17 20 30.14 3.88 5.29 5.06 9.86 4.08 19.00 1.44

aTMB all isomers of TMB, catalys/feed ratio = 5

17

Table 3: Product distribution of toluene alkylation with methanol (toluene/MeOH ratio = 1:1)

on MOR/ZSM-5

Reaction time (s)

Toluene Conv. (%)

Yield (%) Gas Benzene p-

xylene m-xylene o-

xylene Total xylene

aTMBs

300 C

3 5.26 0.60 2.46 1.08 2.22 0.95 4.25 1.03 5 12.12 0.85 3.63 1.80 3.76 1.59 7.14 1.73 7 18.31 1.81 4.76 2.42 4.99 2.10 9.51 1.92 10 22.25 2.19 5.67 2.79 5.85 2.47 11.11 2.37 13 25.47 2.23 6.44 3.35 6.98 2.92 13.25 2.64 15 26.61 2.67 6.64 3.58 7.26 3.06 13.90 2.70 20 34.13 3.83 8.88 4.14 8.76 3.67 16.57 3.33

350 C

3 17.17 1.94 4.47 2.03 4.34 1.90 8.27 1.88 5 21.55 2.32 5.38 2.57 5.56 2.40 10.53 2.25 7 25.91 3.11 6.67 3.02 6.47 2.80 12.29 2.54 10 31.97 3.75 7.64 3.79 5.25 3.50 12.54 3.19 13 34.65 4.22 8.82 4.02 8.57 3.70 16.29 3.25 15 35.98 4.33 8.69 4.26 9.02 3.91 17.19 3.42 20 38.72 4.84 10.19 4.50 9.71 4.19 18.40 3.90

400 C

3 16.10 2.19 4.33 1.83 3.92 1.77 7.52 1.78 5 23.48 2.95 5.78 2.64 5.67 2.56 10.87 2.49 7 24.87 3.45 6.37 2.70 5.77 2.60 11.07 2.36 10 33.47 4.25 8.01 3.80 8.15 3.65 15.60 3.31 13 35.60 4.81 8.81 3.95 8.50 3.86 16.31 3.53 15 37.25 5.19 9.02 4.32 9.24 4.16 17.72 3.74 20 38.27 5.39 10.03 4.28 9.24 4.09 17.61 3.76

aTMB all isomers of TMB, catalyst/feed ratio = 5

18

Table 4: Product distribution of toluene alkylation with methanol (toluene/MeOH ratio = 1:1) on

ZM13

Reaction time (s)

Toluene Conv. (%)

Yield (%) Gas Benzene p-

xylene m-xylene o-

xylene Total

xylene aTMBs

300 C

3 2.45 0.78 0.31 1.50 2.03 0.99 4.52 0.57 5 6.83 1.26 0.44 2.15 3.21 1.45 6.81 0.80 7 9.80 1.50 0.50 2.60 3.92 1.79 8.31 0.99 10 11.38 1.71 0.52 3.14 4.37 2.20 9.71 1.18 13 14.02 1.85 0.54 3.50 5.17 2.51 11.18 1.39 15 14.66 1.89 0.62 3.44 5.37 2.53 11.34 1.46 20 19.17 2.37 0.81 3.75 6.63 2.91 13.29 1.77

350 C

3 7.44 1.18 0.53 1.87 3.35 1.38 6.60 0.87 5 11.16 1.55 0.73 2.41 4.37 1.82 8.60 1.07 7 14.68 1.94 0.79 2.94 5.41 2.25 10.60 1.28 10 19.10 2.31 1.03 3.50 6.75 2.83 13.08 1.59 13 21.86 2.55 1.14 3.85 7.46 3.14 14.45 1.80 15 23.73 2.68 1.29 3.94 7.84 3.32 15.10 1.95 20 26.74 3.00 1.55 4.32 8.86 3.78 16.96 2.26

400 C

3 11.43 1.56 0.79 2.26 4.34 1.82 8.42 1.04 5 16.55 2.07 1.04 2.99 5.85 2.46 11.30 1.36 7 20.91 2.47 1.30 3.63 7.40 3.07 14.10 1.75 10 24.50 2.82 1.79 3.95 8.15 3.54 15.64 1.86 13 26.74 2.87 2.03 4.31 8.93 3.90 17.14 2.02 15 28.62 3.12 2.42 4.63 9.75 4.28 18.66 2.21 20 31.88 3.19 2.64 4.85 10.29 4.59 19.73 2.41 aTMB all isomers of TMB, catalyst/feed ratio = 5

19

Table 5: Estimated kinetic parameters for toluene-methanol (1:1) reaction over HZSM-5,

MOR/ZSM-5 and ZM13 catalysts using TOS model

k1

m6/kgcat.s

( 102)

E1

(kJ/mol)

k2

m6/kgcat.s

( 102)

E2

(kJ/mol)

k3

m6/kgcat.s

( 102)

E3

(kJ/mol)

HZSM-5

values 0.66 54.8 4.50 56.7 1.99 70.0 0.0052

95% CL 0.05 4.7 0.18 3.1 1.45 52.7 0.0039

MOR/ZSM-5

values 3.50 13.1 5.25 20.8 18.29 15.2 0.04

95% CL 0.26 3.0 0.53 7.8 2.49 10.3 0.008

ZM13

values 0.65 20.3 9.09 14.6 10.29 17.8 0.01

95% CL 0.06 5.9 0.31 2.3 0.16 11.7 0.005

Table 6: Estimated kinetic parameters for toluene-methanol (1:1) reaction over HZSM-5,

MOR/ZSM-5 and ZM13 catalysts using RC model

k1

m6/kgcat.s

( 102)

E1

(kJ/mol)

k2

m6/kgcat.s

( 102)

E2

(kJ/mol)

k3

m6/kgcat.s

( 102)

E3

(kJ/mol)

HZSM-5

values 0.76 57.4 5.29 57.1 2.48 65.8 0.60

95% CL 0.11 4.9 0.68 3.1 1.66 48.7 0.40

MOR/ZSM-5

values 8.45 18.2 12.83 23.3 44.52 19.3 2.84

95% CL 2.15 3.5 2.95 7.7 11.60 10.1 0.06

ZM13

values 1.11 23.8 15.20 17.1 17.08 20.5 1.65

95% CL 0.22 5.7 2.51 2.3 3.68 11.2 0.50

20

Table 7: Activation energies for toluene alkylation with methanol reported in literatures

Author Activation Energy (kJ/mol) Catalyst Temperature range (C)

Bhat et. al.19 61 HZSM-8 400 - 450

Sotelo et al.21 60 Mg-Modified ZSM-5 460 - 540

Vinek et al.41 50-55 HZSM-5 300 - 500

Rabiu et.al.23 68 ZSM-5 375 - 450

Odedairo et al.24 47 ZSM-5 300 - 400

Present study 57 HZSM-5 300 - 400