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Evaluation and Modeling Runaway Reaction of Methyl Ethyl Ketone Peroxide Mixed with Nitric Acid Jo-Ming Tseng and Chi-Min Shu* Doctoral Program, Graduate School of Engineering Science and Technology, National Yunlin UniVersity of Science and Technology (NYUST), 123, UniVersity Road, Sec. 3, Douliou, Yunlin, Taiwan 64002, R.O.C.
Jai P. Gupta Department of Chemical Engineering, Indian Institute of Technology, Kanpur, 208016 (U.P.), India
Yan-Fu Lin Department of Chemistry, National Chung Hsing UniVersity, 250, Kuo-Kwang Road, Taichung, Taiwan 40227, R.O.C.
The thermal stability of solutions of methyl ethyl ketone peroxide (MEKPO) dissolved in dimethyl phthalate (DMP), in the presence of nitric acid (HNO3) and sodium nitrate (NaNO3) as contaminants, was studied. MEKPO is extensively employed in the chemical industries, but despite its large use several severe accidents have been recorded in eastern Asia during the past four decades. This study was conducted to elucidate its essentially hazardous characteristics. We used differential scanning calorimetry (DSC) to evaluate the root cause of the runaway reactions, and kinetics-based curve fitting to assess hazardous phenomena by utilizing curve fitting to optimize the kinetic parameters. All the results indicate that the mixture of MEKPO with HNO3 dramatically increases the degree of hazard in the first exothermic peak. In terms of NaNO3, it had no effect on the thermal stability of MEKPO. Introduction
Table 1. Selected Severe Thermal Explosion Accidents Caused by MEKPO in Eastern Asia10
Methyl ethyl ketone peroxide (MEKPO) is widely employed as a cross-linker during polymerization. Martin (1999) indicated that in the curing of an unsaturated polyester (UP) resin MEKPO could be employed as the initiator and cobalt octoate as the promoter of polymerization.1 Minamoto (2002) reported that MEKPO is used as a catalyst and an accelerator for UP systems.2 Pfaffli (1992) found that MEKPO is a “cold catalyst”; when accelerated with cobalt carboxylate, it can even react at room temperature.3 In addition, it is used in various industries, such as the automobile, airline, boating, fabric, and paint, as reported by Fraunfelder and co-workers (1990).4 Historically, MEKPO has caused many serious accidents, because it structurally contains a very sensitive O-O bond. Fires or explosions may be triggered due to uncontrollable thermal sources, resulting in a serious accident that damages the environment or even results in casualties. If the surrounding temperature exceeds 100 °C, MEKPO may decompose immediately. The hazardous characteristics of the O-O bond show that it has a thermally unstable structure, as follows: 1. It is very sensitive to thermal sources. 2. It can yield a large amount of heat during decomposition. 3. It can generate large amounts of gases and mists during decomposition. 4. It is very susceptible to contaminants, such as inorganic acids (H2SO4, H3PO4, HCl, or HNO3), alkali, Fe2O3, and so on. 5. It possesses oxidizing ability.5 The utility of MEKPO mixed with acid has recently been documented. Li and co-workers (2004) reported that when H2* To whom correspondence should be addressed. E-mail: shucm@ yuntech.edu.tw.
date
location
injuries
fatalities
hazard
1979 1996 1964 1978 2000 2001 2003
Taiwan (Taipei) Taiwan (Taoyuan) Japan (Tokyo) Japan (Kanagawa) Korea (Yosu) China (Jiangsu) China (Zhejiang)
49 47 114 0 11 2 3
33 10 19 0 3 4 5
explosion (storage) explosion (tank) explosion explosion explosion explosion explosion
Table 2. Aliases for Different Mixing Conditions material
r (°C min-1)
alias
15 wt % MEKPO (2.90 mg) 15 wt % MEKPO (4.67 mg) 15 wt % MEKPO (2.25 mg) + HNO3 (6 M, 1.34 mg) 15 wt % MEKPO (2.40 mg) + HNO3 (2 M, 1.50 mg) 15 wt % MEKPO (2.70 mg) + NaNO3 (6 M, 1.60 mg)
1 4 4
MP1 MP4 MN6
4
MN2
4
MNA
SO4 (1, 3, and 5 wt %) was used to combine with 55 wt % MEKPO (dissolved in dimethyl phthalate, DMP), the exothermic onset temperature (T0) could be triggered earlier than that of pure MEKPO.6 This phenomenon was also highlighted by Fu and co-workers (2003), who showed that MEKPO when mixed with H2SO4 could significantly decrease the T0.7 Tseng and coworkers also obtained similar conclusions.8 If the thermal source cannot be properly controlled during any stage in the manufacturing process, runaway reactions could be triggered as a consequence. A reactor could be treated as a pivotal unit in causing an accident. A reactor runaway could promote undesired side reactions, catalyst deactivation, and so forth, as indicated by Christoforatou and Balakotaiah (1998).9 Runaway reactions of MEKPO often result in fires or explosions. This study employed differential scanning calorimetry
10.1021/ie0614069 CCC: $37.00 © 2007 American Chemical Society Published on Web 11/03/2007
Ind. Eng. Chem. Res., Vol. 46, No. 25, 2007 8739 Table 3. Thermokinetic Parameters Derived from the DSC Data Sets on 15 wt % MEKPO and Its Contaminants for the First Peak of the Reaction (Figures 2-5)a sample
m (mg)
r (°C min-1)
T0 (°C)
Ea (kJ mol-1)
n1
n2
ln A (ln(s-1))
zb
∆H (J g-1)
MP1 MP4 MN6 MN2 MNA
2.90 4.67 3.59 3.90 4.30
1 4 4 4 4
83.19 126.26 61.38 94.01 93.23
115.68 91.16 64.27 38.94 147.65
1.15 0.63 1.86 1.12 1.19
c c c 0.48 c
29.39 20.42 14.96 6.56 41.27
c c c 0.013 c
208.65 291.48 458.60 411.33 39.74
a MP1, n-order; MP4, n-order; MN6, n-order; MN2, autocatalytic; MNA, n-order. The first peaks of the reactions. Calculated values are based on experimental data sets from DSC tests. Estimated values are in italics. b z, autocatalytic constant.20 c Not applicable.
Table 4. Calculated Thermokinetic Parameters Derived from the DSC Data Sets on 15 wt % MEKPO and Its Contaminants for the Second Peak of the Reaction (Figures 2-5)a sample
m (mg)
r (°C min-1)
Ea (kJ mol-1)
n1
n2
ln A (ln(s-1))
zb
∆H (J g-1)
MP1 MP4 MN6 MN2 MNA
2.90 4.67 3.59 3.90 4.30
1 4 4 4 4
101.4 ( 4.2 79.4 ( 3.4 41.5 ( 1.6 56.1 ( 2.1 74.8 ( 3.1
0.77 ( 0.03 0.34 ( 0.01 4.9 ( 0.1 4.9 ( 0.1 0.74 ( 0.03
0.74 ( 0.03 0. 1.94 ( 0.05 1.17 ( 0.04 c
20.04 14.31 14.51 16.39 16.20
(8.0 ( 0.3) × 10-2 (3.0 ( 0.1) × 10-3 (3.0 ( 0.2) × 10-4 (1.0 ( 0.1) × 10-4 c
185.2 ( 9.2 405.7 ( 13.5 435.2 ( 14.1 260.9 ( 12.2 79.8 ( 3.5
a MP1, autocatalytic; MP4, autocatalytic; MN6, autocatalytic; MN2, autocatalytic; MNA, n-order). The second peaks of the reactions. Calculated values are based on experimental data sets from DSC tests. Estimated values are in italics. b z, autocatalytic constant.20 c Not applicable.
Table 5. Calculated Thermokinetic Parameters Derived from the DSC Data Set on MNA (Figures 2 and 3)a sample MNA
Ea (kJ mol-1)
stage third fourth
93.1 96.4
n2
n1 0.96 0.75
0.65 1.42
ln A (ln(s-1))
zb
∆H (J g-1)
10-2
7.1 × 6.2 × 10-2
17.77 16.65
175.1 218.8
a The third and fourth peaks of MNA. Calculated values are based on experimental data set from DSC test. Estimated values are in italics. b z, autocatalytic constant.20
Table 6. Types of Kinetic Functions
a
sample
f1
f2
f3
f4
MP1 and MP4 MN2 MN6 MNA
(1 - R1)n11 (1 - R1)n11(z1 + R2n12) (1 - R1)n11 (1 - R1)n11
R2n21(z2 + R3n22) R2n21(z2 + R3n22) R2n21(z2 + R3n22) R2n21
a a a R3n31(z3 + R4n32)
a a a R4n41(z4 + R5n42)
Not applicable.
(DSC) to obtain the experimental data sets, which were then used to create useful kinetic models via curve fitting and to estimate the kinetic parameters for MEKPO combined with nitric acid (HNO3). In this work, we have studied the runaway reaction phenomena of MEKPO mixing with HNO3 or sodium nitrate (NaNO3) which could occur in a normal plant, especially during storage or transportation. Since these materials are extensively used, there is always the likelihood, even though small, that they could be mixed accidentally. Thermally sensitive MEKPO can undergo two kinds of reactions: n-order reaction and autocatalytic reaction. Therefore, in the past, only a few of the staff comprehended its characteristics, as very serious casualties were suffered in Taiwan during the Yung-Hsin explosion.10 A few selected accidents involving MEKPO are listed in Table 1. In this study, we determined that MEKPO mixed with HNO3 is very dangeroussinformation that could be provided to plants to lessen the degree of hazard or to instruct plant personnel on how to design a robust control system. Experimental Section Standard Procedure for Preparation of 15 wt % MEKPO. Liquid 31 wt % MEKPO with the solvent 99 wt % DMP was purchased directly from Fluka Co., and stored in a refrigerator at 4 °C. DMP was used as a diluent in preparing the liquid 15
wt % MEKPO samples. After the reaction mixture was stirred at room temperature in the dark for 3.0 h, a concentration of 15 wt % was collected for experimentation. Standard Procedure for Preparation of HNO3 (2, 6 M) and NaNO3 (6 M). Deionized water (H2O) was used as the diluent in preparing the HNO3 and NaNO3 for comparing their influence on pure MEKPO. Standard procedure was followed in using H2O as a diluent with 65 wt % HNO3 and 99.5 wt % NaNO3 to obtain the concentrations of HNO3 (2 and 6 M) and NaNO3 (6 M), respectively. Differential Scanning Calorimetry (DSC). Temperature programmed screening experiments were performed with DSC (Mettler TA8000 system).11 The measuring cell was the essential part of the experiment, as it was used to carry out the experiment for withstanding relatively high pressure to approximately 100 bar (DSC 821e). STARe software was used to obtain thermal curves.11 For better thermal equilibrium, the scanning rate chosen for the temperature programmed ramp was 4 °C min-1.12 The range of temperature rise was chosen from 30 to 350 °C for each experiment. DSC is a popular thermoanalytical technique13 that can be employed to detect the temperature change between the sample and reference. We put the sample and the reference into the furnace heater to reach the temperature under investigation; a thermocouple was used to detect the temperature change (∆T) between the sample and the reference.
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Figure 1. Proposed initiation stage of decomposition mechanisms of pure MEKPO.
When the temperature reached a change point, such as crystallization, boiling point, melting point, or induced thermal decomposition, in the test cell, the environment was triggered to an unbalanced temperature between the sample and the reference, and then the heat flow could be detected immediately for viewing on the thermal curves. MEKPO (15 wt %, 2-3 mg) was doped into a test cell containing HNO3 (2 M, 1.5 mg or 6 M, 1.34 mg) or NaNO3 (6 M, 1.6 mg) for detecting the runaway reactions and temperature. At the beginning of an experiment, the DSC was stabilized for 30 min at 30 °C, and then the experiment was started with a scanning rate of 4 °C min-1. After mixture samples were added to the test cell and they settled in the furnace, the furnace lid was sealed to lessen heat loss. It was also used to keep the gas from getting into the heater area. After the experiments were finished, the samples were weighed again, in order to determine that mass had not been lost during the experiment and to enhance the degree of accuracy. Curve fitting was employed to get the precise kinetic parameters based on the experimental data of time (s), temperature (°C), and heater power (mW). After these three parameters were fitted, the above-mentioned kinetic parameters could be obtained. Processing of experimental data and kinetics evaluation were implemented by applying TDPro and ForK software developed by CISP Ltd. The method is thoroughly described by Kossoy and Akhmetshin (2007) for the creation of a kinetic model and the algorithms that are utilized.14 For further discussion, we used the aliases shown in Table 2 for the samples investigated. Results and Discussion Runaway reactions were investigated based on different experimental data sets. Two concentrations of HNO3 (2 and 6 M) and one concentration of NaNO3 (6 M) were prepared to mix with 15 wt % MEKPO by DSC tests under investigation. These mixture conditions were not used in our earlier studies of simulating or evaluating the kinetic and safety parameters. We have listed the kinetic parameters and experimental data in Tables 3 and 4, respectively. The results indicate the exothermic characteristic phenomena of MEKPO mixed with HNO3 (2 and 6 M) and NaNO3 (6 M). In the past few years, many researchers have worked on autocatalytic reactions. Long et al. (2002) used the autocatalytic hypothesis to evaluate different kinds of reactions and to evaluate the activation energy (Ea) for detecting the autocatalytic decomposition of 2,4,6-trinitrotoluene (TNT).15 Chervin and Bodman (2002) stated that reaction orders of the autocatalytic reactions are associated with the curve shapes of isothermal DSC.16 Meanwhile, Hai and co-workers (2002) applied nonisothermal DSC to estimate the thermal explosion of a first-order autocatalytic decomposition reaction system for highly nitrated
nitrocellulose containing 14.14 wt % nitrogen.17 Leila and Fierz (2002) indicated that if a reaction is autocatalytic and we try to fit the DSC curve by using an n-order thermal model, then we can get a reasonable fit but the Ea will be very highsa real reaction is accelerated by autocatalysis and by temperature rise, and an n-order model describes only temperature acceleration. Therefore, additional temperature acceleration is required to compensate for the autocatalysis. They also revealed that if, for a typical temperature range about 80-300 °C, Ea > 220 kJ mol-1, the reaction is most probably an autocatalytic one. Then, by employing the correct model, a realistic Ea could be obtained.18 There are several well-known methods for evaluating simple autocatalytic models, i.e., for estimating the model parameters. One can derive complex multistage kinetic models that depict autocatalytic phenomena in more detail, but special numerical optimization methods are required to estimate parameters of such models, as discussed by Kossoy and Koludarova (1995)19 for a complex model of two consecutive reactions where the second stage is autocatalytic:
first stage: dR/dt ) A1e-Ea/RT(1 - R)n
n-order reaction
(1)
second stage: dγ/dt ) A2e-Ea/RT(R - λ)n1(z + γn2) autocatalytic reaction (2) Another example can be found in ref 20, where the model of full autocatalysis has been used for description of the decomposition of a nitro compound. This model is comprised of two parallel reactions represented by eqs 3 and 4: r1
a 98 b + other products r2
a + b 98 2b + other products
initiation stage autocatalytic stage
r1 ) k1[a]n1; r2 ) k2[a]n2 [b]n3; r1 , r2
(3) (4) (5)
In practice, a variety of hazard indicators are used for characterization of various aspects of reactive hazards. These includetheself-accelerationdecompositiontemperature(SADT),21,22 temperature of no return (TNR),23 and time to maximum rate (TMR). For this specific case of the MEKPO decomposition, TMR is the appropriate indicator and is defined in adiabatic condition, which allows comparing the degree of hazard among pure MEKPO and MEKPO mixed with HNO3 (2 and 6 M). TMR was proposed by Townsend and Tou in 1980.23 They derived convenient analytical expressions (eqs 6 and 7) for calculation:
TMR )
RT2 e-Ea/RT AEa∆Tad
(6)
Q Cp
(7)
∆Tad )
The main limitation of this method is that the formulas are valid only for simple single-stage n-order reactions. In the case of more complex reactions (including autocatalytic reactions), TMR can be properly determined only by applying a kineticsbased simulation.24 Accordingly, this method has been used in the present study.
Ind. Eng. Chem. Res., Vol. 46, No. 25, 2007 8741
Figure 2. Fitting of experimental data sets on heat production for MP4, MN2, MN6, and MNA by the kinetic functions f1-f4 in Table 6.
Figure 3. Fitting of experimental data sets on heat production rate for MP4, MN2, MN6, and MNA by the kinetic functions f1-f4 in Table 6.
In an earlier paper, Andreozzi et al. (1988) accounted for the TMR for evaluating the different molar ratios of tert-butyl hydroperoxide (TBHP)/p-toluenesulfonic acid (R). The results demonstrated that if the molar ratio R was increased, the value of TMR rose relatively.25 We have used TMR for comparison of potential runaway hazards of pure MEKPO and MEKPO with HNO3. An important practical question with regard to MEKPO is its thermal stability. For assessing this property we applied another indicator, the time to conversion limit (TCL), which is the time required to reach the maximal permissible conversion at constant temperatures, ranging from 20 to 100 °C. As in the case of TMR, this parameter for complex reaction can only be calculated on the basis of a kinetic model. There are many possible reaction pathways with respect to the decomposition of MEKPO. Here, Figure 1 delineates our proposed mechanisms of the initiation stage for the decomposition of pure MEKPO.26,27 However, in the presence of a strong
mineral acid, the activation energy of the initiation stage is decreased. In our experiments, the MEKPO runaway reactions have a similar delay pattern when MEKPO is mixed with the NaNO3 (6 M) solution. Meanwhile, it has been proved that the hydroxyl radical does not react with nitrate anion.28,29 Thus, we assumed that the radicals from the decomposition of MEKPO should react with water to generate hydroxyl radicals. This is the reason why the runaway reaction is temporarily delayed. Our experimental results, however, indicate that 6 M nitric acid solutions exert significant influence on their heat of reaction. The corresponding mechanisms for the reaction of hydroxyl radicals with nitric acid have been reported.30-37 In 6 M nitric acid solutions, 20% of the nitric acid exists in the undissociated form.38 The reaction of hydroxyl radicals with undissociated nitric acid molecules has been proposed for the production of the NO3 radical.29,33,39 In 6 M nitric acid solution, the hydroxyl radical is converted to the NO3 radical via the reaction •OH + HNO3 f H2O + NO3•. Then, the NO3 radicals decompose under
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thermal conditions or react with organic molecules.30,32,37 From these reports, we concluded that the reaction •OH + HNO3 f H2O + NO3• is a major pathway to accelerate the runaway reaction. In terms of kinetic analysis, the dynamic DSC curves consist of several distinct exothermic peaks. The decomposition behavior of MEKPO and MEKPO with contaminants can be adequately described by a formal reaction model of several consecutive stages. The model for decomposition of MP1, MP4, MN2, and MN6 includes two stages: R1,r1
R2,r2
A 98 B 98 C whereas a more complex four-stage model is characteristic for the decomposition of MNA: R1,r1
R2,r2
R3,r3
R4,r4
A 98 B 98 C 98 D 98 E The corresponding mathematical model is represented by the following system of ordinary differential equations:
Figure 4. Fitting of experimental data sets on heat production for MP1 and MP4 by the kinetic function f1 in Table 6.
dR1 ) r1 ) k1(T)f1 dt dR2 ) r1 - r2; r2 ) k2(T)f2 dt dR3 ) r2 - r3; r3 ) k3(T)f3 dt dR4 ) r3 dt t ) 0; Ri ) 0; i ) 1, 2, 3, 4 dQ dt
(8)
4
)
Qi∞ri ∑ i)1
(9)
where R1, R2, R3, and R4 are the conversion degrees of species A, B, C, and D, respectively; ri and Qi∞ denote reaction rate and heat effect of the ith stage, i ) 1, 2, 3, and 4; dQ/dt is the overall rate of heat generation; fi is the kinetic function for the ith stage that depends on conversions. ki(T) obeys the Arrhenius temperature dependence of rate constant: ki(T) ) Ai exp(-Ea,i/ RT), where Ai and Ea,i represent the frequency factor and activation energy of the i stage. R is the gas constant (R ) 8.314 J mol K-1). Table 6 displays the kinetic functions used for describing the decomposition of the studied samples. Selection of appropriate kinetic functions and estimation of kinetic parameters was conducted on the basis of difference data sets from DSC by applying nonlinear optimization coupled with numerical integration of differential equation systems. Curve fitting was employed for this purpose. Tables 3 and 4 summarize the kinetic parameters that provide reasonable data fitting on each sample, as can be seen in Figures 2 and 3. The parameters were estimated on the basis of two data sets, as delineated in Figures 4 and 5, under scanning rates of 1 and 4 °C min-1. Changing the scanning rate abbreviates the reaction time, and the kinetic parameters undergo a significant change. By using curve fitting, we could obtain precise kinetic parameters. Pure MEKPO is more dangerous than di-tert-butyl peroxide (DTBP)40 and cumene hydroperoxide (CHP);12 the results of kinetic evaluation reveal that, when MEKPO is mixed with HNO3 (2 and 6 M), the Ea is lowered to 64.27 and 38.94 kJ
Figure 5. Fitting of experimental data sets on heat production rate for MP1 and MP4 by the kinetic function f1 in Table 6.
mol-1, respectively, compared to that for pure MEKPO of 91.16 kJ mol-1. This indicates that the exothermic ability of the first reaction is prone to increase during the mixture conditions. In terms of the heat of reaction, adding HNO3 (2 or 6 M) into 15 wt % MEKPO resulted in increasing the heat of reaction of the first stage to about 411.33 and 458.60 J g-1 respectively, when compared with pure MEKPO (291.48 J g-1). Thus, by comparing the TMR for different samples at a temperature, we demonstrated that HNO3 exacerbates the degree of hazard, compared with the pure condition. For example, while for pure 15 wt % MEKPO, TMR was about 150 h, on mixing with HNO3 (2 or 6 M), the TMR was reduced to very low values of 1.17 and 0.84 h, respectively. TMR was also simulated on the basis of the kinetic model; results are shown in Figure 6. From Table 4, mixing 15 wt % MEKPO with HNO3 (2 or 6 M) induced the low-peak reactions on the first stage to about 411.33 and 458.60 J g-1, respectively, and then prompted a very high peak reaction after the first one, about 260.88 and 435.15 J g-1, respectively. We employed NaNO3 (6 M) to mix with 15 wt % MEKPO. NaNO3 (6 M) resulted in four peaks forming in the mixture with MEKPO, as presented in Tables 3-5. Each heat of reaction was not very high compared with other conditions, because the amount of thermal duty had been
Ind. Eng. Chem. Res., Vol. 46, No. 25, 2007 8743
Figure 6. TMR vs temperature (kinetics-based simulation) for MP4, MN2, MN6, and MNA.
Figure 7. TCL vs temperature (kinetics-based simulation) for MP4, MN2, MN6, and MNA.
separated and weighted by four peaks, under the same experimental setup, compared with HNO3 (6 M) with 15 wt % MEKPO. Accordingly, NaNO3 (6 M) did not induce 15 wt % MEKPO to produce a clear high peak on the second stage (about 79.75 J g-1), as the configurations illustrate in Figure 3. As a result, MEKPO is more sensitive to HNO3 than to NaNO3. Further analysis of the hazardous potential of MEKPO and the effect of contaminants can be done by comparing TMR and TCL. Figures 6 and 7 disclose dependencies of TMR and TCL on temperature calculated on the basis of the kinetic models. TMR is recognized as a measure of probability of runaway development if an accident occurs. It follows from Figure 6 that, within the range 20-50 °C, MEKPO contaminated by HNO3 is most likely to trigger runaway. Pure MEKPO is less dangerous, whereas NaNO3 as a contaminant ensures the highest level of safety.
TCL characterizes the stability of a product under storage or transportation conditions. For a practical temperature range (2030 °C), pure MEKPO allows a reasonable duration of storage (about 7 days at 30 °C), but MEKPO contaminated by HNO3 could not sustain storage conditions at all. As in the case of runaway probability, MEKPO contaminated by NaNO3 demonstrates the highest level of stability, even better than the pure MEKPO. Conclusions The influence of HNO3 and NaNO3 on the decomposition of MEKPO was studied. Curve fitting was fully employed to model the kinetic parameters and safety parameters precisely to provide hazard information on how to prevent accidents from occurring during transportation or storage. Curve
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fitting was different from the traditional one, because it could account for different kinds of reactions, such as n-order, autocatalytic, single, or consecutive reactions, in each complex reaction. Data processing, kinetics evaluation, and estimation of TMR and TCL were implemented by using the CISP Thermal Safety Software. As for the degree of hazard under runaways, our results from curve fitting and experimental studies provide evidence to show that the degree of hazard with MEKPO significantly increases by mixing with HNO3, while mixing with NaNO3 provides more stability. In order to avoid a runaway reaction, HNO3 should not be allowed to be mixed with MEKPO. Acknowledgment For financial support, we thank the National Science Council (NSC) of Taiwan under Contract No. NSC-93-2214-E-224-003 for this study. In addition, we appreciate the technical assistance provided by Dr. Arcady A. Kossoy of ChemInform Saint Petersburg (CISP), Ltd., St. Petersburg, Russia, and Mr. Anthony M. Janeshek, senior specialist of Dow Chemical, Freeport, TX. Nomenclature A ) frequency factor, s-1 M1-n Cp ) specific heat capacity, J g-1 K Ea ) apparent activation energy, kJ mol-1 fi ) kinetic functions, i ) 1, 2, 3, 4 k ) rate constant, s-1 M1-n m ) mass of reactant, mg ni ) reaction order, dimensionless Q ) specific heat effect of a reaction, J g-1 Qi∞ ) heat effect of the i stage, J g-1 r ) scanning rate, °C min-1 ri ) rate of the ith stage, M s-1 R ) gas constant, 8.314 J mol K-1 T ) temperature, °C TCL ) time to conversion limit, day TMR ) time to maximum rate, h T0 ) exothermic onset temperature, °C z ) autocatalytic constant, dimensionless ∆H ) heat of reaction, J g-1 ∆Tad ) adiabatic temperature rise, °C Ri ) degree of conversion γ ) degree of conversion Literature Cited (1) Martin, J. L. Kinetic Analysis of an Asymmetrical DSC Peak in the Curing of An Unsaturated Polyester Resin Catalyzed with MEKP and Cobalt Octoate. Polymer 1999, 40, 3451. (2) Minamoto, K. Allergic Contact Dermatitis due to Methyl Ethyl Ketone Peroxide, Cobalt Naphthenate and Acrylates in the Manufacture of Fibreglass-Reinforced Plastics. Contact Dermatitis 2002, 46, 58. (3) Pfaffli, P. Determination of Airborne Methyl Ethyl Ketone Peroxide. Fresenius’ J. Anal. Chem. 1992, 342, 183. (4) Fraunfelder, F. T.; Coster, D. J.; Drew, R.; Fraunfelder, F. W. Ocular Injury by Methyl Ethyl Ketone Peroxide. Am. J. Ophthalmol. 1990, 110, 635. (5) Swern, D. Organic Peroxides; John Wiley & Sons: New York, 1970. (6) Li, X.; Koseki, H.; Iwata, Y.; Mok, Y. S. Decomposition of Methyl Ethyl Ketone Peroxide and Mixtures with Sulfuric Acid. J. Loss PreV. Process Ind. 2004, 17, 23. (7) Fu, Z. M.; Li, X. R.; Koseki, H.; Mok, Y. S. Evaluation on Thermal Hazard of Methyl Ethyl Ketone Peroxide by Using Adiabatic Method. J. Loss PreV. Process Ind. 2003, 16, 389.
(8) Tseng, J. M.; Shu, C. M.; Yu, Y. C. Thermal Hazard Simulations for Methyl Ethyl Ketone Peroxide Induced by Contaminants. Korean J. Chem. Eng. 2005, 22, 797. (9) Christoforatou, E. L.; Balakotaiah, V. Runaway Limits for Adiabatic Packed-bed Catalytic Reactors. AIChE J. 1998, 44, 394. (10) Yeh, P. Y.; Shu, C. M.; Duh, Y. S. Thermal Hazard Analysis of Methyl Ethyl Ketone Peroxide. Ind. Eng. Chem. Res. 2003, 42, 1. (11) STARe Software with Solaris Operating System, Operating Instructions; Mettler Toledo: Sweden, 2004. (12) Hou, H. Y.; Shu, C. M.; Duh, Y. S. Exothermic Decomposition of Cumene Hydroperoxide at Low Temperature Conditions. AIChE J. 2001, 47, 1893. (13) Saraf, S. R.; Rogers, W. J.; Mannan, M. S. Application of Transition State Theory for Thermal Stability Prediction. Ind. Eng. Chem. Res. 2003, 42, 1341. (14) Kossoy, A.; Akhmetshin, Yu. Identification of Kinetic Models for the Assessment of Reaction Hazards. Process Saf. Prog. 2007, http:// dx.doi.org/10.1002/prs.10189. (15) Long, G. T.; Brems, B. A.; Wight, C. A. Autocatalytic Thermal Decomposition Kinetics of TNT. Thermochim. Acta 2002, 388, 175. (16) Chervin, S.; Bodman, G. T. Phenomenon of Autocatalysis in Decomposition of Energetic Chemicals. Thermochim. Acta 2002, 392, 371. (17) Hai, Z.; Zhiming, X.; Pengjiang, G.; Rongzu, H.; Shengli, G.; Binke, N.; Yan, F.; Qizhen, S.; Rong, L. Estimation of the Critical Rate of Temperature Rise for Thermal Explosion of First-Order Autocatalytic Decomposition Reaction Systems Using Non-Isothermal DSC. J. Hazard. Mater. 2002, 94, 205. (18) Leila, B. D.; Fierz, H. Autocatalytic Decomposition Reactions, Hazards and Detection. J. Hazard. Mater. 2002, 93, 137. (19) Kossoy, A. A.; Koludarova, E. Specific Features of Kinetics Evaluation in Calorimetric Studies of Runaway Reactions. J. Loss PreV. Process Ind. 1995, 8, 229. (20) Kossoy, A. A.; Hofelich, T. Methodology and Software for Assessing Reactivity Ratings of Chemical Systems. Process Saf. Prog. 2003, 22, 235. (21) Kotoyori, T. The Self-Accelerating Decomposition Temperature (SADT) of Solids of the Quasi-Autocatalytic Decomposition Type. J. Hazard. Mater. 1999, 64, 1. (22) Fisher, H. G.; Goetz, D. D. Determination of Self-Accelerating Decomposition Temperature Using the Accelerating Rate Calorimeter. J. Loss PreV. Process Ind. 1991, 4, 305. (23) Townsend, D. I.; Tou, J. C. Thermal Hazard Evaluation by an Accelerating Rate Calorimeter. Thermochim. Acta 1980, 37, 1. (24) Kossoy, A. A.; Benin, A. I.; Akhmetshin, Y. G. An Advanced Approach to Reactivity Rating. J. Hazard. Mater. 2005, 118, 1. (25) Andreozzi, R.; Caprio, V.; Crescitelli, S.; Russo, G. The Thermal Stability of Tert-Butyl Hydroperoxide-Acid Mixtures. J. Hazard. Mater. 1988, 17, 305. (26) Milas, N. A.; Golubovic, A. Studies in Organic Peroxides. XXV. Preparation, Separation and Identification of Peroxides Derived from Methyl Ethyl Ketone and Hydrogen Peroxide. J. Am. Chem. Soc. 1959, 81, 5824. (27) OSHA. Methyl Ethyl Ketone Peroxide Organic Method # 77; Occupational Safety and Health Administration, U.S.A., 1989. (28) Daniels, M. Pulse Radiolysis of the Aqueous Nitrate System. Formation of NO3 in Concentrated Solutions and the Mechanism of “Direct Action”. J. Phys. Chem. 1966, 70, 3022. (29) Broszkiewicz, R. K. The Radiation-Induced Formation of NO3 in Aqueous Solutions. Int. J. Appl. Radiat. Isotopes 1967, 18, 25. (30) Katsumura, Y.; Jiang, P. Y.; Nagaishi, R.; Oishi, T.; Ishigure, K.; Yoshida, Y. Pulse Radiolysis Study of Aqueous Nitric Acid Solutions: Formation Mechanism, Yield, and Reactivity of NO3 Radical. J. Phys. Chem. 1991, 95, 4435. (31) Connell, P. S.; Howard, C. J. Kinetics Study of the Reaction HO + HNO3. Int. J. Chem. Kinet. 1985, 17, 17. (32) Daniels, M. Radiation Chemistry of the Aqueous Nitrate System. III. Pulse Electron Radiolysis of Concentrated Sodium Nitrate Solutions. J. Phys. Chem. 1969, 73, 3710. (33) Pihcv, A. K.; Sibirskaya, G. K.; Sbirsbov, E. M.; Glazunov, P. Ya.; Spitsyu, V. I. Lbkl. Akad. Nauk SSSR 1974, 215, 645. (34) Neta, P.; Huic, R. E. Rate Constants for Reactions of NO3 Radicals in Aqueous Solutions. J. Phys. Chem. 1986, 90, 4644. (35) Neta, P.; Huie, R. E.; Ross, A. B. Rate Constants for Reactions of Inorganic Radicals in Aqueous Solution. J. Phys. Chem. Ref. Data 1988, 17, 1116. (36) Shastri, L. V.; Huie, R. E. Rate Constants for Hydrogen Abstraction Reactions of NO3 in Aqueous Solution. Int. J. Chem. Kinet. 1990, 22, 505.
Ind. Eng. Chem. Res., Vol. 46, No. 25, 2007 8745 (37) Barnes, I.; Bastian, V.; Becker, K. H.; Tong, Z. Kinetics and Products of the Reactions of NO3 with Monoalkenes, Dialkenes, and Monoterpenes. J. Phys. Chem. 1990, 94, 2413. (38) Rcdlich, O.; Duerst, R. N.; Merbach, A. Ionization of Strong Electrolytes. XI. The Molecular States of Nitric Acid and Perchloric Acid. J. Chem. Phys. 1968, 49, 2986. (39) Kozlowska-Milner, E.; Bmzkiewicz, R. K. Pulse radiolysis of HNO3 and HNO3(aq). Radiat. Phys. Chem. 1978, 11, 253.
(40) Iizuka, Y.; Surianarayanan, M. Comprehensive Kinetic Model for Adiabatic Decomposition of Di-tert-butyl Peroxide Using BatchCAD. Ind. Eng. Chem. Res. 2003, 42, 2987.
ReceiVed for reView November 2, 2006 ReVised manuscript receiVed September 2, 2007 Accepted September 12, 2007 IE0614069
