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Experimental and Detailed Kinetic Modeling Study of Isoamyl Alcohol (Isopentanol) Oxidation in a Jet-Stirred Reactor at Elevated Pressure Guillaume Dayma,*,† Casimir Togbe,‡ and Philippe Dagaut‡ † ‡

Faculte des Sciences 1 rue de Chartres, Universite d’Orleans, BP 6759, 45067 Orleans cedex 2, France Institut des Sciences de l’Ingenierie et des Systemes (INSIS), Centre National de la Recherche Scientifique (CNRS), 1C, Avenue de la Recherche Scientifique, 45071 Orleans cedex 2, France

bS Supporting Information ABSTRACT: Isoamyl alcohol (isopentanol or 3-methylbutan-1-ol) that can be biologically produced is among the possible alcohols usable as an alternative fuel in internal combustion engines. It has a higher energy density than smaller alcohols (ca. 28.5 MJ/L, as compared to ca. 21 MJ/L for ethanol and 27 MJ/L for 1-butanol). It is less hydroscopic than ethanol and mixes better with hydrocarbons. To better understand the combustion characteristics of that alcohol, new experimental data were obtained for its kinetics of oxidation in a jet-stirred reactor (JSR). Concentration profiles of stable species were measured in a JSR at 10 atm over a range of equivalence ratios (0.354) and temperatures (5301220 K). The oxidation of isopentanol was modeled using an extended detailed chemical kinetic reaction mechanism (2170 reactions involving 419 species) derived from a previously proposed scheme for the oxidation of a variety of fuels. The proposed mechanism shows good agreement with the present experimental data. Reaction path and sensitivity analyses were conducted for interpreting the results.

1. INTRODUCTION Because of their sustainable character, biofuels are attracting great interest as transportation fuels. Potentially, they can be locally produced, may be less polluting, sometimes more biodegradable than fossil fuels, and could reduce net greenhouse gas emissions.13 Today, ethanol accounts for over 90% of worldwide biofuel production. However, mixing stability issues may appear with blends containing simple alcohols, whereas larger alcohols mix better with fossil fuels thanks to their longer alkyl chain. Because 1-butanol was announced to be sold in the near future as a gasoline-blending constituent,4 several studies have been performed on its kinetics of oxidation. For example, Dagaut and Togbe studied the oxidation of butanolgasoline surrogate mixtures (8515 vol %) in a jet-stirred reactor (JSR) at 10 atm, and a kinetic reaction mechanism was derived for modeling the oxidation of that fuel.5 Later, longer carbon-chain alcohols, which could be blended with conventional fuels, i.e., 1-pentanol and 1-hexanol, were considered in chemical kinetic studies.6,7 More recently, the interest for using isopentanol in engines was demonstrated.8 In fact, isopentanol has several advantages over smaller alcohols, such as ethanol; it has a high energy density (ca. 28.5 MJ/L, as compared to ca. 21 MJ/L for ethanol and 27 MJ/L for 1-butanol), close to that of gasoline (ca. 32 MJ/L). It is also less hydroscopic than ethanol and mixes better with hydrocarbons. Moreover, isopentanol has a much lower vapor pressure at 293 K (0.27 kPa) than ethanol (5.95 kPa). However, whereas isopentanol could also be produced biologically,911 only engine experiments were reported in the literature,8 which is not enough to assess the kinetics of isopentanol oxidation. Therefore, kinetic studies of the oxidation of that fuel were needed. The aim of this work is to provide new experimental data and a model for the kinetics of isopentanol oxidation under well-defined conditions. New results consisting of stable species concentration r 2011 American Chemical Society

Table 1. Structure, Nomenclature, and Heat of Formation (in kcal mol1) at 298 K of Selected Species

profiles obtained for isopentanol oxidation in a JSR at 10 atm (10.13  105 Pa) over a range of equivalence ratios and temperatures are reported here. This new data set was used to validate a detailed chemical kinetic model for isopentanol oxidation needed for future engine combustion modeling.

2. EXPERIMENTAL SECTION The JSR experimental setup used here has been described earlier.7,12 The reactor consists of a 4 cm diameter fused silica sphere (42 cm3) equipped with four nozzles of 1 mm inner diameter. Prior to the Received: August 8, 2011 Revised: October 6, 2011 Published: October 06, 2011 4986

dx.doi.org/10.1021/ef2012112 | Energy Fuels 2011, 25, 4986–4998

Energy & Fuels

ARTICLE

Table 2. Isopentanol Submechanism (in cm3, mol, s1, and cal) number 1638

A

reaction

n

Ea

butoh3m (+M) = buto3m + H (+M)

6.04  1014

0.1

103800

low pressure limit

2.41  1039

7.03

96000

notea a

TROE centering: 3.87  101/5.65  102/4.44  109/6.71  109 1639

butoh3m = butoh3m-2 + H

5.00  1015

0

94990

b

1640

butoh3m = butoh3m-3 + H

5.00  1015

0

94990

b

1641

butoh3m = butoh3m-4 + H

1.58  1016

0

97970

b

1642

butoh3m = butoh-3 + CH3

2.00  1017

0

84650

b

1643 1644

butoh3m = pC2H4OH + iC3H7 butoh3m (+M) = iC4H9 + CH2OH (+M)

1.58  1017 3.02  1023

0 1.9

85280 85710

estd. a

1.42  1059

11.9

84000

low pressure limit 1

TROE centering: 7.65  10 /8.34  10 /7.25  10 /8.21  10 1645

9

2

9

butoh3m (+M) = but2m-4 + OH (+M)

6.33  1020

1.4

94930

low pressure limit

6.90  1051

10.2

89200

a

TROE centering: 7.03  101/9.88  109/6.35  102/1.79  109 1646

butoh3m + O2 = butoh3m-1 + HO2

1.50  1013

0

50150

c

1647

reverse Arrhenius coefficients butoh3m + O2 = butoh3m-2 + HO2

1.08  109 3.97  1013

0.6 0

504 47690

d

1648

butoh3m + O2 = butoh3m-3 + HO2

3.97  1013

0

43920

d

1649

butoh3m + O2 = butoh3m-4 + HO2

3.97  1013

0

50870

d

1650

butoh3m (+M) = H2O + but3m1d (+M)

3.52  1013

0

67230

a

low pressure limit

1.69  1075

17

64800

TROE centering: 8.00  102/1.00  100/9.92  109/9.92  109 1651

butoh3m + O = buto3m + OH

1.46  103

4.7

1727

e

1652 1653

butoh3m + O = butoh3m-1 + OH butoh3m + O = butoh3m-2 + OH

1.45  105 4.77  104

2.4 2.7

876 2106

e f

1654

butoh3m + O = butoh3m-3 + OH

1.00  1013

0

3280

f

1655

butoh3m + O = butoh3m-4 + OH

1.93  105

2.7

3716

f

1656

butoh3m + H = buto3m + H2

5.55  1023

10.6

4459

g

1657

butoh3m + H = butoh3m-1 + H2

1.79  105

2.5

3420

g

1658

butoh3m + H = butoh3m-2 + H2

1.30  106

2.4

4471

f

1659

butoh3m + H = butoh3m-3 + H2

4.20  106

2

2400

f

1660 1661

butoh3m + H = butoh3m-4 + H2 butoh3m + OH = buto3m + H2O

1.88  105 2.81  102

2.8 3

6280 580

f h

1662

butoh3m + OH = butoh3m-1 + H2O

1.31  105

2.4

1457

h

1663

butoh3m + OH = butoh3m-2 + H2O

4.68  107

1.6

35

f

1664

butoh3m + OH = butoh3m-3 + H2O

1.10  106

2

1870

f

1665

butoh3m + OH = butoh3m-4 + H2O

1.05  1010

1

1590

f

1666

butoh3m + HO2 = buto3m + H2O2

2.50  1012

0

24000

c

1667

butoh3m + HO2 = butoh3m-1 + H2O2

8.20  103

2.5

10750

c

1668 1669

butoh3m + HO2 = butoh3m-2 + H2O2 butoh3m + HO2 = butoh3m-3 + H2O2

5.60  1012 1.00  1012

0 0

17690 14000

f f

1670

butoh3m + HO2 = butoh3m-4 + H2O2

1.68  1013

0

20440

f

1671

butoh3m + CH3 = buto3m + CH4

2.04  100

3.6

7722

i

1672

butoh3m + CH3 = butoh3m-1 + CH4

1.99  101

3.4

7635

i

1673

butoh3m + CH3 = butoh3m-2 + CH4

2.70  104

2.3

7287

f

1674

butoh3m + CH3 = butoh3m-3 + CH4

1.00  1011

0

7900

f

1675

butoh3m + CH3 = butoh3m-4 + CH4

9.04  101

3.6

7154

f

1676 1677

butoh3m + CH3O = butoh3m-1 + CH3OH butoh3m + CH3O = butoh3m-2 + CH3OH

1.10  1011 1.10  1011

0 0

5000 5000

f f

1678

butoh3m + CH3O = butoh3m-3 + CH3OH

1.90  1010

0

2800

f

1679

butoh3m + CH3O = butoh3m-4 + CH3OH

2.16  1011

0

7000

f

1680

butoh3m + CH3O2 = butoh3m-1 + CH3O2H

5.60  1012

0

17690

f

1681

butoh3m + CH3O2 = butoh3m-2 + CH3O2H

5.60  1012

0

17690

f

1682

butoh3m + CH3O2 = butoh3m-3 + CH3O2H

1.50  1012

0

15000

f

4987

dx.doi.org/10.1021/ef2012112 |Energy Fuels 2011, 25, 4986–4998

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Table 2. Continued number

reaction

A

n

Ea

notea

1683 1684

butoh3m + CH3O2 = butoh3m-4 + CH3O2H butoh3m + C2H3 = butoh3m-1 + C2H4

1.68  1013 4.00  1011

0 0

20440 16800

f f

1685

butoh3m + C2H3 = butoh3m-2 + C2H4

4.00  1011

0

16800

f

1686

butoh3m + C2H3 = butoh3m-3 + C2H4

2.00  1011

0

16800

f

1687

butoh3m + C2H3 = butoh3m-4 + C2H4

1.02  1012

0

18000

f

1688

butoh3m + C2H5 = butoh3m-1 + C2H6

5.00  1010

0

10400

f

1689

butoh3m + C2H5 = butoh3m-2 + C2H6

5.00  1010

0

10400

f

1690

butoh3m + C2H5 = butoh3m-3 + C2H6

2.50  1010

0

10400

f

1691 1692

butoh3m + C2H5 = butoh3m-4 + C2H6 buto3m = CH2O + iC4H9

1.02  1011 1.00  1013

0 0

13400 13190

f j

1693

butoh3m-1 = CH3CHO + iC3H7

1.52  1012

0.6

31120

estd.

1694

butoh3m-2 = butoh2d + CH3

2.00  1013

0

31000

f

1695

butoh3m-3 = iC4H8 + CH2OH

2.00  1013

0

27700

estd.

1696

butoh3m-4 = C3H6 + pC2H4OH

2.37  1012

0.5

28890

a

1697

butoh3m-4 = CH3 + butoh3d

2.00  1013

0

31000

f

1698

butoh3m-2 = but3m1d + OH

6.67  1015

0.9

27660

a

1699

reverse Arrhenius coefficients buto3m = butal3m + H

9.93  1011 8.89  1010

0 0.5

960 2620

k

1700

butoh3m-1 = butal3m + H

3.07  1014

0.5

34700

a

1701

butoh3m-2 + M = butal3m + H + M

1.00  1014

0

25000

c

1702

butoh3m-2 = butoh3m2d + H

1.50  1013

0

37500

f

1703

butoh3m-3 = butoh3m2d + H

3.00  1013

0

38000

f

1704

butoh3m-3 = butoh3m3d + H

6.00  1013

0

39000

f

1705

butoh3m-4 = butoh3m3d + H

1.50  1013

0

37500

f

1706 1707

buto3m + O2 = butal3m + HO2 butoh3m-1 + O2 = butal3m + HO2

4.00  1010 1.00  1013

0 0

1100 5564

l m

1708

butoh3m-2 + O2 = butal3m + HO2

4.50  1011

0

2500

n

1709

butoh3m-2 + O2 = butoh3m2d + HO2

4.50  1011

0

5000

n

1710

butoh3m-3 + O2 = butoh3m2d + HO2

1.58  1012

0

5000

n

1711

butoh3m-3 + O2 = butoh3m3d + HO2

1.38  1012

0

5000

n

1712

butoh3m-4 + O2 = butoh3m3d + HO2

4.50  1011

0

5000

n

1713

butoh3m3d + OH = CH2O + butoh-3

1.37  1012

0

1040

o

1714 1715

butoh3m3d + OH = CH3COCH3 + pC2H4OH butoh3m2d + OH = CH3COCH3 + pC2H4OH

1.37  1012 1.37  1012

0 0

1040 1040

o o

1716

but3m1d + OH = CH2O + iC4H9

1.37  1012

0

1040

o

1717

but3m1d + OH = CH3CHO + iC3H7

1.37  1012

0

1040

o

1718

but3m1d + OH = CH3 + iC3H7CHO

1.37  1012

0

1040

o

1719

butoh2d + OH = CH3CHO + pC2H4OH

1.37  1012

0

1040

o

1720

butoh2d + OH = C2H5CHO + CH2OH

1.37  1012

0

1040

o

1721

butoh3d + OH = CH3CHO + pC2H4OH

1.37  1012

0

1040

o

1722 1723

but3m1d = C4H7-3 + CH3 but3m1d + H = iC4H8 + CH3

2.00  1016 7.23  1012

0 0

72930 1302

b p

1724

but3m1d + H = but2m-3

1.32  1013

0

1560

f

1725

but3m1d + H = but2m-4

1.32  1013

0

3260

f

1726

but3m1d + CH3 = pent2m-3

1.69  1011

0

7400

f

1727

but3m1d + CH3 = but2m3m-1

9.64  1010

0

8000

f

1728

but2m-3 = c2C4H8 + CH3

2.00  1013

0

31000

f

1729

but2m-3 = t2C4H8 + CH3

2.00  1013

0

31000

f

1730 1731

but2m-4 = C2H4 + iC3H7 pent2m-3 = c2C5H10 + CH3

2.00  1013 2.00  1013

0 0

27700 31000

f f

1732

pent2m-3 = t2C5H10 + CH3

2.00  1013

0

31000

f

1733

but2m3m-1 = C3H6 + iC3H7

2.00  1013

0

27700

f

1734

butoh2d + O = HOC4H6 + OH

1.74  1011

0.7

5900

f

1735

butoh2d + H = HOC4H6 + H2

1.74  105

2.5

2510

f

4988

dx.doi.org/10.1021/ef2012112 |Energy Fuels 2011, 25, 4986–4998

Energy & Fuels

ARTICLE

Table 2. Continued number

A

reaction

n

notea

Ea

1736 1737

butoh2d + OH = HOC4H6 + H2O butoh2d + HO2 = HOC4H6 + H2O2

3.00  106 9.60  103

2 2.6

298 13900

f f

1738

butoh2d + CH3 = HOC4H6 + CH4

2.22  100

3.5

5670

f

1739

butoh2d + O = HOC4H6-2 + OH

8.80  1010

0.7

3250

f

1740

butoh2d + H = HOC4H6-2 + H2

5.40  104

2.5

1900

f

1741

butoh2d + OH = HOC4H6-2 + H2O

3.00  106

2

1520

f

1742

butoh2d + HO2 = HOC4H6-2 + H2O2

6.40  103

2.6

12400

f

1743

butoh2d + CH3 = HOC4H6-2 + CH4

1.00  1011

0

7300

f

1744 1745

HOC4H6-2 + O2 = sC3H5CHO + HO2 HOC4H6-2 = sC3H5CHO + H

7.90  1011 2.50  1013

0 0

5000 29000

n f

1746

butoh2d = C4H7-3 + OH

5.89  1019

1

95950

a

1747

butoh2d = C3H5-s + CH2OH

2.21  1022

1.6

97520

a

reverse Arrhenius coefficients

2.41  1013

0

butoh3d + O = HOC4H6 + OH

8.80  1010

0.7

reverse Arrhenius coefficients

2.00  1013

0

1749

butoh3d + H = HOC4H6 + H2

5.40  104

2.5

1900

f

1750 1751

butoh3d + OH = HOC4H6 + H2O butoh3d + HO2 = HOC4H6 + H2O2

3.00  106 6.40  103

2 2.6

1520 12400

f f

1752

butoh3d + CH3 = HOC4H6 + CH4

1.00  1011

0

7300

f

1753

HOC4H6 + H = butoh2d

1.00  1014

0

0

f

1754

HOC4H6 + H = butoh3d

1.00  1014

0

0

f

1755

but3m1d + H = but3m1dt + H2

2.50  104

2.5

2790

f

1756

but3m1d + OH = but3m1dt + H2O

1.30  106

2

2620

f

1757

but3m1d + HO2 = but3m1dt + H2O2

1.60  104

2.6

10900

f

1758 1759

but3m1d + CH3 = but3m1dt + CH4 but3m1dt + O2 = isope + HO2

5.00  1010 1.38  1012

0 0

5600 15200

f n

1760

isope + H = but3m1dt

1.00  1014

0

0

f

1761

but3m1dt + H = but3m1d

1.00  1014

0

0

f

1762

but3m1dt + H = but2m2d

1.00  1014

0

0

f

1763

but3m1dt + HO2 = CH3COCH3 + C2H3 + OH

4.50  1012

0

0

q

1764

but3m1dt + HO2 = iC4H7v + CH2O + OH

4.50  1012

0

0

q

1765

but3m1d + O = but3m1dp + OH

1.93  105

2.7

3716

f

1766 1767

but3m1d + H = but3m1dp + H2 but3m1d + OH = but3m1dp + H2O

1.88  105 1.05  1010

2.8 1

6280 1590

f f

1768

but3m1d + HO2 = but3m1dp + H2O2

1.68  1013

0

20440

f

1769

but3m1d + CH3 = but3m1dp + CH4

9.04  101

3.6

1770

but3m1dp = C4H6 + CH3

2.00  1013

1771

but3m1dp = C3H6 + C2H3

1772

1748

0 3250

f

0

7154

f

0

31000

f

2.00  1013

0

35500

f

isope + H = but3m1dp

1.00  1014

0

0

1773

but3m1dp + O2 = isope + HO2

7.50  1010

0

2500

1774 1775

but3m1dp + H = but3m1d C2H3 + C3H5-t = isope

1.00  1014 5.00  1013

0 0

0 0

1776

isope + OH = CH2O + iC4H7

1.37  1012

0

1040

o

1777

isope + OH = CH3CHO + C3H5-t

1.37  1012

0

1040

o

1778

isope + OH = CH3 + iC3H5CHO

1.37  1012

0

1040

o

1779

isope + OH = CH2O + C4H7-3

1.37  1012

0

1040

o

1780

isope + O = isopy + OH

1.74  1011

0.7

5900

f

1781

isope + H = isopy + H2

1.74  105

2.5

2510

f

1782 1783

isope + OH = isopy + H2O isope + HO2 = isopy + H2O2

3.00  106 9.60  103

2 2.6

298 13900

f f

1784

isope + CH3 = isopy + CH4

2.22  100

3.5

5670

f

1785

isopy = C3H4-a + C2H3

2.00  1013

0

50000

f

1786

isopy + HO2 = CH2O + iC4H5 + OH

4.50  1012

0

0

q

1787

isopy + H = isope

1.00  1014

0

0

estd.

4989

estd. n estd. estd.

dx.doi.org/10.1021/ef2012112 |Energy Fuels 2011, 25, 4986–4998

Energy & Fuels

ARTICLE

Table 2. Continued number

reaction

A

n

Ea

notea

1788 1789

but2m-3 = but2m2d + H but2m-4 + O2 = but3m1d + HO2

1.50  1013 1.58  1012

0 0

37500 5000

f n

1790

but2m-3 + O2 = but3m1d + HO2

6.90  1011

0

5000

n

1791

but2m-3 + O2 = but2m2d + HO2

4.50  1011

0

5000

n

a

Note: estd., estimated; (a) Black et al. Combust. Flame 2010, 157, 363373; (b) Dean et al. J. Phys. Chem. 1985, 89, 46004608; (c) Marinov Int. J. Chem. Kinet. 1999, 31, 183220; (d) Tsang J. Phys. Chem. Ref. Data 1988, 17, 887; (e) Wu et al. J. Phys. Chem. A 2007, 111, 66936703; (f) Touchard Ph.D. Thesis, Institut National Polytechnique de Lorraine, Nancy, France, 2005; (g) Park et al. J. Chem. Phys. 2003, 118, 99909996; (h) Xu et al. Proc. Combust. Inst. 2007, 31, 159166; (i) Xu et al. J. Chem. Phys. 2004, 120, 65936599; (j) Johnson et al. Atmos. Environ. 2004, 38, 17551765; (k) Curran Int. J. Chem. Kinet. 2006, 38, 250275; (l) Hartmann et al. Ber. Bunsen-Ges. 1990, 94, 639645; (m) Natarajan et al. Proc. Int. Symp. Shock Waves 1982, 13, 834; (n) Battin-Leclerc Prog. Energy Combust. Sci. 2008, 34, 440498; (o) Heyberger et al. Combust. Flame 2001, 126, 17801802; (p) Tsang J. Phys. Chem. Ref. Data 1991, 20, 221273; (q) Stothard et al. J. Chem. Soc., Faraday Trans. 1990, 86, 21152119.

injectors, the reactants were diluted with nitrogen (