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Selective hydrogenation of unsaturated aldehyde over hydrogen storage alloy
Journal of Alloys and Compounds 375 (2004) 202–204
Selective hydrogenation of unsaturated aldehyde over hydrogen storage alloy Hiroshi Yamada∗ , Makiko Fujimura, Shigeo Goto Department of Chemical Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan Received 3 June 2003; received in revised form 1 September 2003; accepted 2 October 2003
Abstract Selective hydrogenation of unsaturated aldehyde was carried out with hydrogen storage alloy, Mg2 Ni. The storage hydrogen and the feed hydrogen gas were used for hydrogenation. Products selectivity depended on hydrogen source. The release rate of the storage hydrogen was important for high selectivity to unsaturated alcohol. The selectivity to unsaturated alcohol became 100% at 393 K, when ethanol was fed with reactant and Co was deposited on Mg2 Ni. © 2004 Elsevier B.V. All rights reserved. Keywords: Selective hydrogenation; Unsaturated aldehyde; Croton aldehyde; Hydrogen source; Mg2 Ni
1. Introduction Unsaturated aldehydes have both C=C and C=O double bonds. They can be partially hydrogenated to unsaturated alcohols or saturated aldehydes. Saturated alcohols can be finally produced by complete hydrogenation. Unsaturated alcohols are objective products in this paper because they are more valuable than the other products. Metal hydrides such as NaBH4 , LiAlH4 selectively hydrogenate C=O double bonds [1]. However, these metal hydrides are not suitable for industrial operation, because they cannot be reused. On the other hands, hydrogen storage alloys can be used repeatedly. Many papers reported about hydrogenation of unsaturated organic compound or carbon dioxide with hydrogen storage alloy [2–4]. However, there were a few studies which unsaturated aldehydes were used as reactants. Imamoto [5] studied the hydrogenation of unsaturated aldehydes over LaNi5 H6 . Hydrogenation were proceeded at 0 ◦ C through to room temperature. At first, saturated aldehydes were produced and then it was hydrogenated to saturated alcohol. In this paper Mg2 Ni was used for selective hydrogenation of croton aldehyde, unsaturated aldehyde, to crotyl alcohol,
∗ Corresponding author. Tel.: +81-52-789-4529; fax: +81-52-789-3387. E-mail address: [email protected] (H. Yamada).
0925-8388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2003.09.160
unsaturated alcohol. Two kinds of hydrogen source, that was storage in the alloy and the feed hydrogen gas were used.
2. Experimental 2.1. Procedure An electrically heated tubular flow type reactor was used. 2.71 g of Mg2 Ni or 2.85 g of 5 wt.% Co/Mg2 Ni was diluted with 3.47 g of glass particle and put into the reactor. The reactant was crotonaldehyde. It is one of the unsaturated aldehydes. Before the reaction, hydrogen gas was fed into the reactor for one night at room temperature to adsorb hydrogen into the hydrogen storage alloy. The reactor was heated to reaction temperature with hydrogen flow. Two kinds of operations were carried for reaction. One was the operation that the reactant was fed into the reactor with helium. The reactant was hydrogenated with the storage hydrogen in the alloy. The other was the operation that the reactant was fed into the reactor with hydrogen gas. The reactant was mainly hydrogenated with the feed hydrogen gas. Standard conditions were as follows: crotonaldehyde flow rate 1.7 × 10−7 mol/s, helium or hydrogen flow rate 1.9 × 10−5 mol/s, reaction temperature 473 K. The products were analyzed mainly by FID gas chromatograph with HP-INNOWAX column.
H. Yamada et al. / Journal of Alloys and Compounds 375 (2004) 202–204
2.2. Materials
203
Co/Mg2 Ni (5 wt.%) was prepared according to the following method. CoCl2 ·6H2 O was dissolved in ethanol. Mg2 Ni (0.25–0.50 mm in diameter) and ethanol solution was evaporated in the rotary evaporator. Activation of the alloy was carried out according to the following method. Hydrogen gas was fed into the tubular reactor at atmospheric pressure. The reactor was heated to 623 K and held at this temperature for 2 h. Then, the reactor was cooled to room temperature, and held at this temperature for one night.
Conversion, Selectivity [%]
100 80 Butyl aldehyde
60 Conversion
40 Propylene
20 0 0
10
20
30
40
Time [min.]
Fig. 2. Hydrogenation over storage hydrogen Mg2 Ni (T: 473 K).
3. Experimental results and discussions 3.1. Reaction scheme
3.2. Mg2 Ni Crotonaldehyde was hydrogenated with the storage hydrogen. Fig. 2 shows the experimental results. The conversion of croton aldehyde and the selectivity to n-butyl aldehyde and propylene are marked on the figure. n-Butyl aldehyde and a little propylene were produced. Equimolar amount of propylene and carbon monoxide were produced. Carbon monoxide is omitted in figures in this paper. The conversion of crotonaldehyde decreases with time and becomes very low after 50 min, because the storage hydrogen was decreased with time. Fig. 3 shows the results of the hydrogenation of croton aldehyde with the feed hydrogen gas. The conversion of croton aldehyde is 100% even after 50 min. n-Butyl aldehyde and propylene were produced. The selectivity to n-butyl
aldehyde is lower than that of Fig. 2. Therefore, the feed hydrogen gas and the storage hydrogen have different property for the selectivity on hydrogenation. Crotyl alcohol was not produced when Mg2 Ni was used. 3.3. Co/Mg2 Ni The polar solutions increase the selectivity to the unsaturated alcohol at liquid phase hydrogenation because C=O double bond is polar [6]. To increase the selectivity to crotyl alcohol, ethanol was added to the reactant. Ethanol flow rate was 4.2 × 10−8 mol/s. Cobalt has high selectivity to the unsaturated alcohol [7]. Then, 5 wt.% Co was deposited on Mg2 Ni.
100 Conversion, Selectivity [%]
Fig. 1 shows the reaction scheme of the hydrogenation of crotonaldehyde (unsaturated aldehyde, CH3 CH=CHCHO). Crotyl alcohol (unsaturated alcohol, CH3 CH=CHCH2 OH) and n-butyl aldehyde (saturated aldehyde, CH3 (CH2 )2 CHO) are intermediate products. n-Butanol (saturated alcohol, CH3 (CH2 )3 OH) is formed through crotyl alcohol or n-butyl aldehyde. Crotyl alcohol is the objective product. A part of crotonaldehyde is decomposed to propylene (CH3 CH=CH2 ) and carbon monoxide (CO).
80
Butyl aldehyde
60 40 Propylene
20
0 0
CH3 (CH2 )2CHO
Conversion
100
200
Time[min.]
CH 3CH =CHCHO
CH 3(CH2 )3 OH CH3CH=CHCH 2 OH
CH3CH=CH 2 + CO Fig. 1. Reaction scheme.
Fig. 3. Hydrogenation over hydrogen gas Mg2 Ni (T: 473 K).
204
H. Yamada et al. / Journal of Alloys and Compounds 375 (2004) 202–204
100 Conversion, Selectivity [%]
Conversion, Selectivity [%]
100 Conversion
80 Propylene
60 40
Butanol
20 0 0
Crotyl alcohol
80 60 40 Conversion
20
Crotyl alcohol
50
100
150
0 0
200
Fig. 4. Hydrogenation over storage hydrogen Co/Mg2 Ni ethanol (T: 473 K).
Fig. 4 shows the experimental results of the hydrogenation with the storage hydrogen. Propylene and n-butanol were produced at first. The conversion of croton aldehyde is 100%. Then, crotyl alcohol was produced with decrease of the conversion and the selectivity to n-butanol. It means that n-butanol is hydrogenated from crotyl alcohol and low release rate of the storage hydrogen is important for the high selectivity to crotyl alcohol. Fig. 5 shows the experimental results of the hydrogenation with the feed hydrogen gas. Propylene and 1-butanol were produced. Crotyl alcohol was immediately hydrogenated to 1-butanol. Crotyl alcohol was not produced. Storage hydrogen is required to produce crotyl alcohol.
100
Fig. 6. Hydrogenation over storage hydrogen Co/Mg2 Ni ethanol (T: 393 K).
The hydrogenation with storage hydrogen at low reaction temperature, 393 K, was carried. Hydrogen release rate is decreased at the low reaction temperature. Fig. 6 shows the effect of temperature. The conversion becomes lower while the selectivity to crotyl alcohol becomes 100%. 4. Conclusion The release rate of storage hydrogen from hydrogen storage alloy is important for the high selectivity to crotyl alcohol. The selectivity to crotyl alcohol becomes 100% at 393 K, when ethanol was fed with reactant and Co was deposited on Mg2 Ni. Nomenclature
100 Conversion, Selectivity [%]
50 Time [min.]
Time [min.]
Conversion
80
T
reaction temperature (K)
Propylene
60 40
Butanol
References
20 0 0
50
100
Time [min.]
Fig. 5. Hydrogenation over hydrogen gas Co/Mg2 Ni ethanol (T: 473 K).
[1] H. Hart, R.D. Schuetz, Organic Chemistry: A Short Course, Fifth ed., Houghton Mifflin Company, Boston, 1978, p. 205. [2] S. Nakagawa, S. Murata, T. Sakai, M. Nomura, Chem. Lett. (1994) 431–432. [3] G. Zhu, Y. Lei, Q. Wang, X. Yang, J. Alloys Comp. 253/254 (1997) 689. [4] H. Ando, M. Fujiwara, Y. Matsumura, H. Miyamura, H. Tanaka, Y. Souma, J. Alloys Comp. 223 (1995) 139. [5] T. Imamoto, T. Mita, M. Yokoyama, J. Chem. Soc. Chem. Commun. (1984) 163. [6] H. Yamada, S. Goto, J. Chem. Eng. Jpn. 36 (2003) 586. [7] C. Ando, H. Kurokawa, H. Miura, Appl. Catal. A: Gen. 185 (1999) L181.
Selective hydrogenation of unsaturated aldehyde over hydrogen storage alloy Hiroshi Yamada∗ , Makiko Fujimura, Shigeo Goto Department of Chemical Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan Received 3 June 2003; received in revised form 1 September 2003; accepted 2 October 2003
Abstract Selective hydrogenation of unsaturated aldehyde was carried out with hydrogen storage alloy, Mg2 Ni. The storage hydrogen and the feed hydrogen gas were used for hydrogenation. Products selectivity depended on hydrogen source. The release rate of the storage hydrogen was important for high selectivity to unsaturated alcohol. The selectivity to unsaturated alcohol became 100% at 393 K, when ethanol was fed with reactant and Co was deposited on Mg2 Ni. © 2004 Elsevier B.V. All rights reserved. Keywords: Selective hydrogenation; Unsaturated aldehyde; Croton aldehyde; Hydrogen source; Mg2 Ni
1. Introduction Unsaturated aldehydes have both C=C and C=O double bonds. They can be partially hydrogenated to unsaturated alcohols or saturated aldehydes. Saturated alcohols can be finally produced by complete hydrogenation. Unsaturated alcohols are objective products in this paper because they are more valuable than the other products. Metal hydrides such as NaBH4 , LiAlH4 selectively hydrogenate C=O double bonds [1]. However, these metal hydrides are not suitable for industrial operation, because they cannot be reused. On the other hands, hydrogen storage alloys can be used repeatedly. Many papers reported about hydrogenation of unsaturated organic compound or carbon dioxide with hydrogen storage alloy [2–4]. However, there were a few studies which unsaturated aldehydes were used as reactants. Imamoto [5] studied the hydrogenation of unsaturated aldehydes over LaNi5 H6 . Hydrogenation were proceeded at 0 ◦ C through to room temperature. At first, saturated aldehydes were produced and then it was hydrogenated to saturated alcohol. In this paper Mg2 Ni was used for selective hydrogenation of croton aldehyde, unsaturated aldehyde, to crotyl alcohol,
∗ Corresponding author. Tel.: +81-52-789-4529; fax: +81-52-789-3387. E-mail address: [email protected] (H. Yamada).
0925-8388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2003.09.160
unsaturated alcohol. Two kinds of hydrogen source, that was storage in the alloy and the feed hydrogen gas were used.
2. Experimental 2.1. Procedure An electrically heated tubular flow type reactor was used. 2.71 g of Mg2 Ni or 2.85 g of 5 wt.% Co/Mg2 Ni was diluted with 3.47 g of glass particle and put into the reactor. The reactant was crotonaldehyde. It is one of the unsaturated aldehydes. Before the reaction, hydrogen gas was fed into the reactor for one night at room temperature to adsorb hydrogen into the hydrogen storage alloy. The reactor was heated to reaction temperature with hydrogen flow. Two kinds of operations were carried for reaction. One was the operation that the reactant was fed into the reactor with helium. The reactant was hydrogenated with the storage hydrogen in the alloy. The other was the operation that the reactant was fed into the reactor with hydrogen gas. The reactant was mainly hydrogenated with the feed hydrogen gas. Standard conditions were as follows: crotonaldehyde flow rate 1.7 × 10−7 mol/s, helium or hydrogen flow rate 1.9 × 10−5 mol/s, reaction temperature 473 K. The products were analyzed mainly by FID gas chromatograph with HP-INNOWAX column.
H. Yamada et al. / Journal of Alloys and Compounds 375 (2004) 202–204
2.2. Materials
203
Co/Mg2 Ni (5 wt.%) was prepared according to the following method. CoCl2 ·6H2 O was dissolved in ethanol. Mg2 Ni (0.25–0.50 mm in diameter) and ethanol solution was evaporated in the rotary evaporator. Activation of the alloy was carried out according to the following method. Hydrogen gas was fed into the tubular reactor at atmospheric pressure. The reactor was heated to 623 K and held at this temperature for 2 h. Then, the reactor was cooled to room temperature, and held at this temperature for one night.
Conversion, Selectivity [%]
100 80 Butyl aldehyde
60 Conversion
40 Propylene
20 0 0
10
20
30
40
Time [min.]
Fig. 2. Hydrogenation over storage hydrogen Mg2 Ni (T: 473 K).
3. Experimental results and discussions 3.1. Reaction scheme
3.2. Mg2 Ni Crotonaldehyde was hydrogenated with the storage hydrogen. Fig. 2 shows the experimental results. The conversion of croton aldehyde and the selectivity to n-butyl aldehyde and propylene are marked on the figure. n-Butyl aldehyde and a little propylene were produced. Equimolar amount of propylene and carbon monoxide were produced. Carbon monoxide is omitted in figures in this paper. The conversion of crotonaldehyde decreases with time and becomes very low after 50 min, because the storage hydrogen was decreased with time. Fig. 3 shows the results of the hydrogenation of croton aldehyde with the feed hydrogen gas. The conversion of croton aldehyde is 100% even after 50 min. n-Butyl aldehyde and propylene were produced. The selectivity to n-butyl
aldehyde is lower than that of Fig. 2. Therefore, the feed hydrogen gas and the storage hydrogen have different property for the selectivity on hydrogenation. Crotyl alcohol was not produced when Mg2 Ni was used. 3.3. Co/Mg2 Ni The polar solutions increase the selectivity to the unsaturated alcohol at liquid phase hydrogenation because C=O double bond is polar [6]. To increase the selectivity to crotyl alcohol, ethanol was added to the reactant. Ethanol flow rate was 4.2 × 10−8 mol/s. Cobalt has high selectivity to the unsaturated alcohol [7]. Then, 5 wt.% Co was deposited on Mg2 Ni.
100 Conversion, Selectivity [%]
Fig. 1 shows the reaction scheme of the hydrogenation of crotonaldehyde (unsaturated aldehyde, CH3 CH=CHCHO). Crotyl alcohol (unsaturated alcohol, CH3 CH=CHCH2 OH) and n-butyl aldehyde (saturated aldehyde, CH3 (CH2 )2 CHO) are intermediate products. n-Butanol (saturated alcohol, CH3 (CH2 )3 OH) is formed through crotyl alcohol or n-butyl aldehyde. Crotyl alcohol is the objective product. A part of crotonaldehyde is decomposed to propylene (CH3 CH=CH2 ) and carbon monoxide (CO).
80
Butyl aldehyde
60 40 Propylene
20
0 0
CH3 (CH2 )2CHO
Conversion
100
200
Time[min.]
CH 3CH =CHCHO
CH 3(CH2 )3 OH CH3CH=CHCH 2 OH
CH3CH=CH 2 + CO Fig. 1. Reaction scheme.
Fig. 3. Hydrogenation over hydrogen gas Mg2 Ni (T: 473 K).
204
H. Yamada et al. / Journal of Alloys and Compounds 375 (2004) 202–204
100 Conversion, Selectivity [%]
Conversion, Selectivity [%]
100 Conversion
80 Propylene
60 40
Butanol
20 0 0
Crotyl alcohol
80 60 40 Conversion
20
Crotyl alcohol
50
100
150
0 0
200
Fig. 4. Hydrogenation over storage hydrogen Co/Mg2 Ni ethanol (T: 473 K).
Fig. 4 shows the experimental results of the hydrogenation with the storage hydrogen. Propylene and n-butanol were produced at first. The conversion of croton aldehyde is 100%. Then, crotyl alcohol was produced with decrease of the conversion and the selectivity to n-butanol. It means that n-butanol is hydrogenated from crotyl alcohol and low release rate of the storage hydrogen is important for the high selectivity to crotyl alcohol. Fig. 5 shows the experimental results of the hydrogenation with the feed hydrogen gas. Propylene and 1-butanol were produced. Crotyl alcohol was immediately hydrogenated to 1-butanol. Crotyl alcohol was not produced. Storage hydrogen is required to produce crotyl alcohol.
100
Fig. 6. Hydrogenation over storage hydrogen Co/Mg2 Ni ethanol (T: 393 K).
The hydrogenation with storage hydrogen at low reaction temperature, 393 K, was carried. Hydrogen release rate is decreased at the low reaction temperature. Fig. 6 shows the effect of temperature. The conversion becomes lower while the selectivity to crotyl alcohol becomes 100%. 4. Conclusion The release rate of storage hydrogen from hydrogen storage alloy is important for the high selectivity to crotyl alcohol. The selectivity to crotyl alcohol becomes 100% at 393 K, when ethanol was fed with reactant and Co was deposited on Mg2 Ni. Nomenclature
100 Conversion, Selectivity [%]
50 Time [min.]
Time [min.]
Conversion
80
T
reaction temperature (K)
Propylene
60 40
Butanol
References
20 0 0
50
100
Time [min.]
Fig. 5. Hydrogenation over hydrogen gas Co/Mg2 Ni ethanol (T: 473 K).
[1] H. Hart, R.D. Schuetz, Organic Chemistry: A Short Course, Fifth ed., Houghton Mifflin Company, Boston, 1978, p. 205. [2] S. Nakagawa, S. Murata, T. Sakai, M. Nomura, Chem. Lett. (1994) 431–432. [3] G. Zhu, Y. Lei, Q. Wang, X. Yang, J. Alloys Comp. 253/254 (1997) 689. [4] H. Ando, M. Fujiwara, Y. Matsumura, H. Miyamura, H. Tanaka, Y. Souma, J. Alloys Comp. 223 (1995) 139. [5] T. Imamoto, T. Mita, M. Yokoyama, J. Chem. Soc. Chem. Commun. (1984) 163. [6] H. Yamada, S. Goto, J. Chem. Eng. Jpn. 36 (2003) 586. [7] C. Ando, H. Kurokawa, H. Miura, Appl. Catal. A: Gen. 185 (1999) L181.