Methyl at Ion of Glycerol With Dimethyl Sulfate to Produce New Oxygenates for Fuels

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Article

Methylation of Glycerol with Dimethyl Sulfate toProduce a New Oxygenate Additive for Diesels

Jyh-Shyong Chang, Yu-Da Lee, Lawrence Chao-Shan Chou, Tzong-Rong Ling, and Tse-Chuan ChouInd. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/ie201612t • Publication Date (Web): 06 Dec 2011

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Methylation of Glycerol with Dimethyl Sulfate to Produce a New Oxygenate

Additive for Diesels

Jyh-Shyong Changa*

, Yu-Da Leea, Lawrence Chao-Shan Chou

b, Tzong-Rong Ling

c, and

Tse-Chuan Choua,d

aDepartment of Chemical Engineering, Tatung University, 40 Chungshan North Road, 3rd

Sec., Taipei, Taiwan, ROC

bDepartment of Chemical Engineering, Case Western Reserve University, Cleveland, OH

44106, USA

cDepartment of Chemical Engineering, I-Shou University, 1, Section 1, Hsueh-Cheng

Road, Ta-Hsu Hsiang, Kaohsiung 84008,, Taiwan, ROC

dDepartment of Chemical Engineering, National Cheng Kung University,

Tainan 701,

Taiwan, ROC

* Author to whom correspondence should be addressed

Telephone number: +886-2-1822928-6266

Fax number: +886-2-5861939

E-mail: [email protected]

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Abstract

A new oxygenate additive for diesels (bio or petroleum) was manufactured using glycerol,

dimethyl sulfate (DMS), and sodium hydroxide pellets as raw materials. By feeding the

dimethyl sulfate into the batch reactor containing the sodium glycerate, a semibatch mode

operation enhanced the effective methylation of glycerol. A conventional stirred tank

reactor that can produce large quantities of oxygenate additives under a normal

atmospheric pressure operation became the main feature of the methylation process. With

a 3:2 molar ratio of DMS to glycerol, a 3:1 molar ratio of sodium hydroxide to glycerol, a

0.43:1 molar ratio of water to sodium hydroxide, and a temperature of 343 K at the

reaction time of 24 hours with the feeding time of DMS under 12 hours, the conversion of

glycerol (93.5%) and a combined yield of GDMEs and GTME of 71.2% were achieved

for a once-through operation. A product mixture of GDME (20 wt%) and GTME (80 wt%)

served as a new oxygenate additive for (bio or petroleum) diesels.

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1. Introduction

Oxygenates are used as additives for both gasoline and diesel. The gasoline

oxygenates are added to enhance the octane rating of internal combustion engines and to

reduce air pollution by ensuring a more complete fuel combustion in the engines.

Meanwhile, the use of oxygenated compounds with diesel is designed to reduce harmful

exhaust emissions, namely particulates, and sometimes NOx as well.1 The two main

families of oxygenated additives are alcohols and ethers. Alcohols are less interesting

because they have several drawbacks1,2

such as high water solubility, high Reid vapor

pressure (RVP), high volatility, high latent heat of vaporization, and a low heating value.

These drawbacks result in phase separation problems: clogging of the fuel flow, increase

of the volatile organic compound emissions, cold startup and drivability issues, and a low

heating value. By contrast, ethers, aside from retaining all the benefits of alcohols without

any separation problems, give high octane numbers, enhance gasoline combustion, and

reduce CO emissions.1

Oxygenate utilization, used to produce cleaner burning diesel fuels, has been noted

for over fifty years. Diethylene glycol dimethyl ether (DGM) and dibutyl ether (DBE) are

known as diesel cetane enhancers.1 In recent years, tert-butyl ethers of glycerol with a

high content of di-ethers produced by the etherification of glycerol with isobutylene or

tert-butyl alcohol using homogeneous or solid acid catalysts have been considered

promising as oxygenate additives for diesel fuels.3-8

The etherification of glycerol with

ethanol over solid acid catalysts can transform glycerol into monoalkyl glyceryl ethers

(MAGEs). MAGEs are interesting intermediates for the production of various chemicals,

among them dioxolane.9 With the objective of introducing new large-scale processes

based on glycerol transformation, dioxanes and dioxolanes can be interesting targets,

serving as excellent candidates to be used as co-fuels for the diesel fraction.9 The

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etherification of glycerol with methanol to produce glycerol mono-methoxy ethers

(GMMEs), di-methoxy ethers (GDMEs), and tri-methoxy ether (GTME) as a green

solvent can be found in the work of Garciá et al.10

3-methoxy-1,2-propanediol (CAS

623-39-2), 2-methoxy-1,3-propanediol (CAS 761-06-8) are the isomers of GMME; 1,3 or

2,3-dimethoxy-1-propanol (CAS 40453-77-8); 1,3-dimethoxy-2-propanol (CAS 623-69-8)

are the isomers of GDME, and 1,2,3-trimethoxypropane (20637-49-4)) is GTME.

Nevertheless, the possible oxygenate additive composed of glycerol di-methoxy ethers

and tri-methoxy ether for gasoline or diesel fuels have not been developed. GMME is a

promising cryoprotector in the low-temperature preservation of blood cells, bone marrow,

and reinoculated cell cultures.11

The production of the mixture of GDMEs and GTME as

oxygenate additive is promising,12-16

because the feedstock of methanol is much cheaper

than that of isobutylene or tert-butyl alcohol and a large amount of glycerol is being

produced during the transesterification of fatty acids into biodiesel.

The etherification reactions addressed above are generally operated under the

autogenic pressure in an autoclave. Depending on the reacting component (methanol,

ethanol, isobutylene or tert-butyl alcohol) involved in the reaction with glycerol, the

operating pressure ranges from several to around 100 atmospheric pressures. The

requirement of an autoclave to carry out these etherification reactions of glycerol will

hinder the production of a large quantity of the reacting medium, for an autoclave is

normally very expensive. Hence, the methylation of glycerol with alcohol using a suitable

methylation agent is deemed to be another synthetic route to produce the oxygenate

additive, because the methylation reaction is typically operated under normal atmospheric

pressure and thus a large quantity of the reacting medium can easily be processed in a

conventional stirred tank reactor. Procedures for preparing GMMEs were addressed in the

work of Koshchii11

involving preparations of sodium glycerate from equimolar amounts

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of anhydrous glycerol and powdered NaOH, followed by alkylation with alkyl halides to

obtain glycerol 1-monoalkyl ethers. We performed experiments to refine the conditions

for preparing the mixture of GDMEs and GTME as an oxygenate additive to gasoline or

diesel. Our goal was to find the methods and conditions that would ensure the highest

yield of the target products with the simpler possible procedure. For the route to GDMEs

and GTME, we chose the methylation of glycerol with dimethyl sulfate (DMS) in the

presence of alkali. It seemed appropriate to refine the effects of the synthesis parameters

(reaction time, reaction temperature, molar ratio of sodium hydroxide to water, and DMS

feeding time) on the yield and isomeric composition of the product.

In the following section, the main properties of the mixture of GDMEs and GTME

as a new oxygenate additive are introduced. Section 3 presents the experimental system

including glycerol methylation, product separation procedure, and product analysis.

Section 4 gives the main experimental results and discussion. Finally, the conclusions are

presented.

2. Main Properties of the Mixture of GDMEs and GTME as a New Oxygenate

Additive

The laboratory of Chinese Petroleum Company (CPC) in Taiwan analyzes the

collected product of GDMEs (20 wt%) and GTME (80 wt%) mixture. The product

properties are being used to compare with the existing diesel cetane enhancers DGM and

DBE, shown in Table 1. From the comparison, we conclude that the product mixture of

GDMEs (20 wt%) and GTME (80 wt%) can serve as a new oxygenate additive for diesels

(bio or petroleum).

3. The Experimental Section

3.1. Glycerol Methylation and Product Separation Procedure. The synthesis of

GDMEs and GTME involved the following steps: (1) mixing glycerol with NaOH and

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H2O in the molar ratio NaOH : glycerol = 3 : 1, NaOH : H2O = 2.35 : 1; (2) reflux

under reduced pressure (130 mm Hg) on an oil bath, with the bath temperature gradually

increased to 70℃ for half an hour; (3) adding DMS to the resulting sodium glycerate

(GONa) at 70℃ over a period of 5 h in the molar ratio DMS : glycerol = 3 : 2; (4)

removing Na2SO4 from the reaction mixture; (5) distilling the product mixture of CH3OH,

H2O, GDMEs and GTME from the bottoms at 180 Co /130 mm Hg; (6) extracting

GDMEs and GTME form the product mixture obtained in step 5 with chloroform in the

volume ratio CHCl3 : product mixture = 1.5 : 1 overnight; and (7) distilling the extracted

phase to remove chloroform at 90 Co /130 mm Hg to obtain the final product mixture

GDMEs and GTME. The total yield of the final product mixture was 31.8 %.

3.2. Product Analysis. A gas chromatograph, CHINA GC2000, which was provided

with a capillary column Varian CP9210 (l, 30 m; i.d., 0.32 mm; film thickness, 0.5 mm)

under the oven temperature program from 40 to 250 Co (with a heating rate of

10 Co min-1

) and at 250 Co for 3 min, analyzed the sample of the reaction products.

0.2µl of the sample was injected manually. Each data set was obtained with an accuracy

of %5.2± from an average of three independent measurements, using the internal

standard method (n-butanol, 2 wt.% in respect to the sample). Water content was

measured with the Karl Fisher Titrator, MKS-500. For quantification of the reaction

product, the GDMEs and GTME components were separated and used as the standards.

The standard 3-methoxy-1,2-propanediol (one isomer of GMMEs) was purchased from

Alfa Aesar. The way to obtain pure GDMEs and GTME components and characterization

of these two standards are summarized in the Appendix.

The glycerol conversion is defined as

Go

GGoG

)(

N

NNX

−= (1)

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and the yield of glycerol ethers is defined as

0

i

i

G

P

PN

NY = (2)

where GX is the conversion of glycerol (mol %); iPY ( iP represents GMMEs (i=1),

GDMEs (i=2), and GTME (i=3)) is the yield of different glycerol ethers (mol %); 0GN

and GN are the amounts of starting glycerol (mol) and the resulting glycerol (mol),

respectively;iPN is the total amount of glycerol ethers (mol).

4. Results and Discussions

When the methylation of glycerol with DMS synthesized the glycerol ether in the

presence of NaOH, the sodium glycerate reacted with DMS, and five glycerol ether

isomers were potentially produced including two GMMEs (3-methoxy-1,2-propanediol

and 2-methoxy-1,3-propanediol), two GDMEs (1,3-dimethoxy-2-propanol and 2,3-

dimethoxy-2-propanol), and one GTME (1,2,3-trimethoxypropane), as shown in Figure

117

. The GDMEs and GTBE were the desired products in this reaction. While, methanol

and sodium sulfate were the by-products. All the experimental data shown in the

following figures were the average of duplicative experiments.

4.1. Effects of Reaction Times. To study the influence of reaction time on the glycerol

methylation reaction, experiments using the same loading velocity of DMS were

implemented at 6, 12, 24, and 48 h. Minor variations in the conversion of glycerol are

observed in Figure 2(a); at the reaction time of 6, 12 and 24 h, the conversion of glycerol

reached 97%; but, at the reaction time of 48 h, the conversion dropped slightly to 96%.

However, the reaction time influenced the yield of glycerol ethers. In the mixture of

glycerol ethers, the yield of GMMEs obviously decreased from the reaction hour of 12 to

24 but the yield of GMMEs maintained at the hour of 48 (Figure 2(b)). The yield of

GDMEs decreased from the reaction hour of 6 to 24 and GTME manifested the opposite

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tendency with respect to the yield of GDMEs (Figure 2(a) and 2(b)). The methylation of

glycerol in this work was aimed at the combined yield of GDMEs and GTME; therefore,

the target performance of the process is conspicuously treated in the figures. Figure 2 (a)

shows the combined yield of GDMEs and GTME and Figure 2 (b) displays the yields of

GMMEs and GDMEs at the end of the reaction stage (step (3) described in Section 3.1)

and the separation stage (step (7)), respectively. The yield of GTME at the end of the

reaction increased as the reaction time increased, but the combined yield of GDMEs and

GTME at the end of the reaction reached the maximum (75.5%) at the time of 24 h and

dropped slightly at the time of 48 h. However, the maximal combined yield of GDMEs

and GTME at the end of the extraction and separation was reduced to 31.8%, because the

high solubility of GDMEs in the aqueous phase of the product mixture hindered the

recovery of GDMEs in the non-aqueous phase of the adopted solvent (chloroform) during

the extraction and distillation. These results can be explained as follows: The glycerol

methylation reaction was comprised of consecutive reversible steps: first, in the presence

of aquous NaOH, glycerol transformed into sodium glycerate. Consecutive reversible

reactions between sodium glycerate and DMS led to GMMEs, GDMEs, and GTME

(Figure 1). The transformation of GMMEs, GDMEs and GTME was enhanced with the

increase of the reaction time. However, the possible side reaction between DMS and H2O

reduced the availability of DMS (Figure 1); the maximal combined yield of GDMEs and

GTME occurred at 24 h rather than at 48 h. The presence of methanol in the product

mixture confirmed the occurrence of this side reaction. Considering the purpose of the

optimization was to obtain a high glycerol conversion and a high combined yield of

GDMEs and GTME, 24 h was thus considered as a suitable reaction time in this

experimental system.

4.2. Effects of Reaction Temperatures. To study the influence of the reaction

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temperature on the glycerol methylation reaction, experiments were conducted at 323,

343, 363, and 383 K. As shown in Figure 3(a), the conversion of glycerol increased with

the increase of temperature from 50 Co to 110 Co but showed little conversion at 323 K;

by contrast, a near complete conversion of glycerol (97%) was obtained at 343 K after 24

h. Nevertheless, the results showed that the conversion exhibited a decrease from

temperature 70 to 90 Co and also at 110 Co . As is also shown in Figure 3(b), the yield of

GMMEs increased from 50 Co to 110 Co ; that of GDMEs increased from 50 Co to

70 Co and then dropped at 90 Co and increased at 110 Co ; that of GTME increased from

50 Co to 70 Co and then fell from 70 Co to 110 Co (Figure 3(a) and 3(b)). In Figure

3(a), the combined yield of GDMEs and GTME reached the maximum (75.5%) at the end

of the reaction and at the end of the extraction and separation dropped to 31.8% at 70 Co .

In general, a comparatively higher temperature normally initiates a higher reaction rate.

Because a higher temperature could enhance the back-reactions 1, 3, an 5 shown in

Figure 1, which would lead to an decrease in the formations of GTME as shown in Figure

3(a) and 3(b). In the mean time, the reaction between DMS and H2O is an undesired side

reaction that also depends on reaction time and temperature. Higher reaction temperature

would promote this side reaction which would consume a large amount of DMS and

might influence the glycerol conversion and yield of GTME. Based on these

considerations, 70 Co was chosen as the optimizing temperature.

4.3. Effect of Molar Ratio of Water to Sodium Hydroxide. From the proposed overall

reaction network for the methylation of glycerol (Figure 1), water is a detrimental factor

to the production of the ethers due to the reversible reactions 1, 3, 5, and 7 shown in

Figure 1. However, enough initial loading of water could dissolve sodium hydroxide

pellets properly and facilitate the mixing of the dissolved sodium hydroxide with the rest

of reactants. Therefore, the effect of the H2O to NaOH molar ratio on the methylation

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reaction was studied using four different ratios in the range from 0 (anhydrous) to 2.78.

As shown in Figure 4(a), the glycerol reached a constant conversion (97 5.0± %) and the

yield of GDMEs and GTME in the glycerol ether mixture decreased with an increase in

the molar ratio from 0.43 to 2.78. With a further decrease in the molar ratio from 0.43 to

0 (anhydrous), the reaction ceases to occur, because anhydrous glycerol cannot dissolve

any sodium hydroxide pellet. The yield of GTME decreased at the end of the reaction as

the molar ratio of H2O to NaOH increased, and the combined yield of GDMEs and

GTME reached the maximum (75.5%) at the end of the reaction under the molar ratio of

0.43 (Figure 4(a) and 4(b)). However, the maximal combined yield of GDMEs and

GTME at the end of extraction and separation reduced to 31.8%, because the high

solubility of GDMEs in the aqueous phase of the product mixture reduced the recovery of

GDMEs in the non-aqueous phase of the adopted solvent (chloroform) during extraction

and distillation. Basing on these considerations, the molar ratio of H2O to NaOH (0.43)

was chosen as the optimizing initial water loading.

4.4. Effects of the Feeding Time of Dimethyl Sulfate. The feeding time of DMS is one

of the important factors influencing the reaction rate, for this highly exothermic reaction

favors a semibatch operation. Therefore, the effect of the feeding time of DMS on the

glycerol methylation reaction was investigated with various feeding time intervals of

DMS in the range from 1 to 23 h. A short feeding time means a high feed rate. As

shown in Figure 5(a), the conversion of glycerol climbed with the increasing feeding time

at the hour of 1 and 5; then it dropped and maintained at 93.5% from hour 12 to hour 23.

The highest conversion was obtained when the feeding time of DMS was hour 5. The

combined yield of GDMEs and GTME reached 75.5% at the end of reaction and dropped

to 31.8% at the end of the extraction and separation reduced under the feeding time of

DMS (5 h) as depicted in Figure 5 (a). However, a higher combined yield of GDMEs and

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GTME (34.5 %) at the end of the extraction and separation reduced under the feeding

time of DMS (12 h) can be observed. Under this feeding time of DMS (12 h), more

GTME was produced than that operated under 5 h feeding time and more GDMEs and

GTME were extracted and separated as depicted in Figure 5 (a). For the lowest feed rate

of DMS (the feeding time 23 h), the side reaction (reaction 7 depicted in Figure 1)

reduced the availability of DMS. The results of the reactions characterized by low yield

of GTME are shown in Figure 5(a). Therefore, the optimizing feeding time of DMS for

this experimental system was found to be 12 h. Figure 5(b) displays the yield variations

of GMMEs and GDMEs over the DMS feeding time. For the lowest feed rate of DMS

(the feeding time 23 h), the highest yield of GMMEs results in the low yield of GDMEs

and GTME (Figure (a)).

5. Conclusions

The methylation of glycerol with DMS in the presence of alkali under an optimizing

condition produces the product mixture of GDMEs (20 wt%) and GTME (80 wt%). This

mixture serves as a new possible oxygenate additive for diesels (bio or petroleum). The

properties of this new oxygenate additive for diesels are comparable to those of DGM and

DBE. A normal atmospheric pressure operation of the methylation of glycerol with

dimethyl sulfate is the main feature that large quantities of oxygenate additive can easily

be manufactured in a conventional stirred tank reactor.

The conversion of glycerol (93.5%) and the combined yield of GDMEs and GTME

(71.2%) were obtained using a 3:2 molar ratio of dimethyl sulfate to glycerol, a 3:1 molar

ratio of sodium hydroxide to glycerol, a 0.43:1 molar ratio of water to sodium hydroxide,

and a temperature of 343 K under the reaction time of 24 h with the feeding time of

dimethyl sulfate under 12 h. The maximal combined yield of GDMEs and GTME at the

end of the extraction and separation fell to 34.5% for a once-through operation. The

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recycle of GMMEs and GDMEs could further improve the yield of the final products.

Acknowledgments

Financial support from the National Science Council (Grant NSC

98-3114-E-036-001) is gratefully acknowledged.

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Appendix: Preparation and Identification of the Standards for GDMEs and GTME

A preparation of the standards for GDMEs and GTME involved the following

steps: (1) Mix the final product mixture obtained in Section 3.1 with CHCl3 and H2O in

the volume ratio CHCl3 : product mixture = 1 : 1 and H2O : product mixture = 2 : 1; (2)

Separate the aqueous phase and non-aqueous phase first, and then identify whether the

components of GDMEs still exist in the non-aqueous phase using GC analysis. If the

non-aqueous phase still contains GDMEs, remove the aqueous phase and go back to step

(1); (3) Distill the non-aqueous phase containing CHCl3 and GTME to obtain pure GTME

from the bottoms at 110 Co /130 mm Hg; (4) Distill the collected aqueous phase

containing H2O and GDMEs to obtain pure GDMEs from the bottoms at 100 Co /130 mm

Hg. The corresponding GC analyses of the final reaction mixture of the purified GTME

and GDMEs are presented in Figures A1-A3. The standard GMMEs was purchased from

Alfa Aesar and its GC analysis is shown in Figure A4.

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Caption of Table

Table 1. Comparison of Main Properties of the New Oxygenate Additive with the

Existing Additives

Caption of Figures

Figure 1. The proposed overall reaction network for the production of GMMEs, GDMEs

and GTME from glycerol and DMS.

Figure 2. The influence of the reaction time on (a) the conversion GX and the combined

yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction temperature, 343 K;

H2O/NaOH molar ratio, 0.43; feeding time of DMS, 5 hr and (b) the yields of the desired

products at the end of reaction ( GMMEsY and GDMEsY ) and at the end of extraction and

separation ( GMMEsf,Y and GDMEsf,Y ) (glycerol, 0.435 mole; DMS/glycerol molar ratio, 1.5;

NaOH/glycerol molar ratio, 3).

Figure 3. The influence of the reaction temperature on (a) the conversion GX and the

combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction time, 24 hr;

H2O/NaOH molar ratio, 0.43; feeding time of DMS, 5 hr and (b) the yields of the desired




Figure 4. The influence of the molar ratio of H2O/NaOH on (a) the conversion GX and

the combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction time, 24 h;

reaction temperature, 343 K; feeding time of DMS, 5 hr and (b) the yields of the desired



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Figure 5. The influence of the DMS feeding time on (a) the conversion GX and the

combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction time, 24 h; reaction

temperature, 343 K; H2O/NaOH molar ratio, 0.43 and (b) the yields of the desired




Figure A1. Exemplary GC chromatographic analysis. 1-methanol; 2-n-butanol;

3-1,2,3-trimethoxypropane; 4-1,3-dimethoxy-2-propanol; 5-2,3-dimethoxy-1-propanol;

6-3-methoxy-1,2-propanediol; 7-2-methoxy-1,3-propanediol; 8-glycerol.

Figure A2. Exemplary GC chromatographic analysis. 1-1,2,3-trimethoxypropane.

Figure A3. Exemplary GC chromatographic analysis. 1-1,2,3-trimethoxypropane;

2-1,3-dimethoxy-2-propanol; 3-2,3-dimethoxy-1-propanol.

Figure A4. Exemplary GC chromatographic analysis. 1-1,3-dimethoxy-2-propanol;

2-2,3-dimethoxy-1-propanol; 3-3-methoxy-1,2-propanediol.

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Table 1. Comparison of Main Properties of the New Oxygenate Additive with the Existing Additives

*: The oxygenates mixtures are composed of GDMEs (20 wt%) and GTME (80 wt%)

Oxygenates of this work* Existing Oxygenates1

GDMEs GTME DGM DBE

CAS No.

Chemical formula

Chemical structure

Molecular weight, kg/kmol

Normal boiling point, K

Density, kg/m3

Heat of combustion, J/kg

Flash point, K

Lower flammability limit, %vol

Autoignition temperature, K

Cetane number

Lower heating value, kJ/g

623-69-8 40453-77-8 20637-49-4

C5H12O3 C5H12O3 C6H14O3

(CH3OCH2)2CHOH

CH3OCH2CH(OCH3)CH2OH

(CH3OCH2)2CHOCH3

120 120 134

442 453 421

968

-2.74×107

322

1.47

-

58

25.12

11-96-6

C6H14O3

(CH3OCH2CH2)2O

134

435

937

-2.52×107

343

1.2

-

112

24.5

142-96-1

C8H18O

(C4H9)2O

130.2

414

764

-3.80×107

298

1.5

467

91-100

-

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Figure 1. The proposed overall reaction network for the production of GMMEs, GDMEs and GTME from glycerol and DMS.17

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Time (h)

Time (h)

(a)

(b)

Conversion and yield

(%

)

0 6 12 24 480

10

20

30

40

50

60

YGMMEs

Yf,GMMEs

YGDMEs

Yf,GDMEs

Yield

(%

)

0 6 12 24 480

20

40

60

80

100

XG

YGDMEs+GTME

Yf,GDMEs+GTME

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Figure 2. The influence of the reaction time on (a) the conversion GX and the

combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction temperature,

343 K; H2O/NaOH molar ratio, 0.43; feeding time of DMS, 5 hr and (b) the yields of

the desired products at the end of reaction ( GMMEsY and GDMEsY ) and at the end of

extraction and separation ( GMMEsf,Y and GDMEsf,Y ) (glycerol, 0.435 mole; DMS/glycerol

molar ratio, 1.5; NaOH/glycerol molar ratio, 3).

.

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(a)

(b)

50 70 90 1100

10

20

30

40

50

YGMMEs

Yf,GMMEs

YGDMEs

Yf,GMMEs

50 70 90 1100

20

40

60

80

100

XG

YGDMEs+GTME

Yf,GDMEs+GTME

Yield

(%

)Conversion and yield

(%

)

Temperature (oC)

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Figure 3. The influence of the reaction temperature on (a) the conversion GX and

the combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction time, 24 hr;

H2O/NaOH molar ratio, 0.43; feeding time of DMS, 5 hr and (b) the yields of the

desired products at the end of reaction ( GMMEsY and GDMEsY ) and at the end of

extraction and separation ( GMMEsf,Y and GDMEsf,Y ) (glycerol, 0.435 mole;

DMS/glycerol molar ratio, 1.5; NaOH/glycerol molar ratio, 3).

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(a)

(b)

0 0.43 0.74 2.780

10

20

30

40

50

YGMMEs

Yf,GMMEs

YGDMEs

Yf,GDMEs

H2O/NaOH molar ratio (mol/mol)

0 0.43 0.74 2.780

20

40

60

80

100

XG

YGDMEs+GTME

Yf,GDMEs+GTME

Yield

(%

)Convers

ion and yield

(%

)

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Figure 4. The influence of the molar ratio of H2O/NaOH on (a) the conversion

GX and the combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction

time, 24 h; reaction temperature, 343 K; feeding time of DMS, 5 hr and (b) the

yields of the desired products at the end of reaction ( GMMEsY and GDMEsY ) and at the

end of extraction and separation ( GMMEsf,Y and GDMEsf,Y ) (glycerol, 0.435 mole;

DMS/glycerol molar ratio, 1.5; NaOH/glycerol molar ratio, 3).

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DMS feeding time (h)

1 5 12 230

20

40

60

80

100

XG

YGDMEs+GTME

Yf,GDMEs+GTME

1 5 12 230

10

20

30

40

50

YGMMEs

Yf,GMMEs

YGDMEs

Yf,GDMEs

(a)

(b)

Yield

(%

)Convers

ion and yield

(%

)

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Figure 5. The influence of the DMS feeding time on (a) the conversion GX and the

combined yield of GDMEsf,Y and GTMEf,Y . Reaction conditions: reaction time, 24 h;

reaction temperature, 343 K; H2O/NaOH molar ratio, 0.43 and (b) the yields of the

desired products at the end of reaction ( GMMEsY and GDMEsY ) and at the end of

extraction and separation ( GMMEsf,Y and GDMEsf,Y ) (glycerol, 0.435 mole; DMS/glycerol

molar ratio, 1.5; NaOH/glycerol molar ratio, 3).

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Figure A1. Exemplary GC chromatographic analysis. 1-methanol; 2-n-butanol;

3-1,2,3-trimethoxypropane; 4-1,3-dimethoxy-2-propanol;

5-2,3-dimethoxy-1-propanol; 6-3-methoxy-1,2-propanediol;

7-2-methoxy-1,3-propanediol; 8-glycerol.

Time (min)

FID

res

ponse

(m

v)

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Figure A2. Exemplary GC chromatographic analysis. 1-1,2,3-trimethoxypropane.

Time (min)

FID

resp

onse

(m

v)

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Figure A3. Exemplary GC chromatographic analysis. 1-1,2,3-trimethoxypropane;

2-1,3-dimethoxy-2-propanol; 3-2,3-dimethoxy-1-propanol.

Time (min)

FID

resp

onse

(m

v)

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Figure A4. Exemplary GC chromatographic analysis. 1-1,3-dimethoxy-2-propanol;

2-2,3-dimethoxy-1-propanol; 3-3-methoxy-1,2-propanediol.

Time (min)

FID

resp

onse

(m

v)

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Methyl at Ion of Glycerol With Dimethyl Sulfate to Produce New Oxygenates for Fuels

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