Investigation of three types of catalysts for the hydration of ethylene oxide (EO) to monoethylene glycol (MEG)

Hal, J.W. van; Ledford, John; Zhang, Xiankuan

doi:10.1016/j.cattod.2007.02.015

“…[12][13][14] However, the catalyst stability is a major challenge because the resins swell under reaction conditions. 15,16 No industrialization of catalytic hydration has been achieved because of the problems of catalysis. Therefore, the development catalysts with high thermal stability and high selectivity and conversion is urgent.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a polymer/multiwalled carbon nanotube composite and its application in the hydration of ethylene oxide

Yu¹,

Chen²,

He³

et al. 2009

J of Applied Polymer Sci

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Multiwalled carbon nanotubes (MWNTs) were incorporated into the crosslinking network of a styrene-divinylbenzene copolymer (PS-DVB) via suspension polymerization. The prepared crosslinking PS-DVB with MWNTs was first treated with chloromethyl methyl ether to introduce chloromethyl groups through Friedel-Craft reaction; then, the chloromethylation product was reacted with trimethyl amine to obtain the target polymer/carbon nanotube composite: PS-DVB/MWNT ion-exchange resin. The obtained composite was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results show the successful incorporation of MWNTs into the polymer network. The physical and chemical properties of the PS-DVB/MWNT ion-exchange resin were nearly the same as those of the controlled sample. With its excellent antiswelling properties, the catalytic behavior of the polymer composite was examined in the hydration of ethylene oxide. Also, it demonstrated excellent stability as a catalyst without a decline in conversion and selectivity in a long-time run.

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“…Various types of catalysts, including liquid and solid acids or bases, have been explored, such as sulfuric acid, [3] the salts of some acids, [4] cyclic amines, [5] cation-and anion-exchange resins, [6] quaternary phosphonium halides, [7] polymeric organosilane ammonium salts, [8] macrocyclic chelating compounds, [9] and supported metal oxides. [10] However, a high H 2 O/EO molar ratio (i.e.…”

mentioning

confidence: 99%

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors

Li

¹

,

Bai

²

,

Wang

³

et al. 2012

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Monoethylene glycol (MEG) and 1,2-propylene glycol (PG) are important raw materials for the manufacture of polyester resins, antifreezes, cosmetics, medicines, and other products. [1] The total global demand for MEG has been estimated to be over 19 million metric tons per year.[2] The production of MEG in industry predominantly involves the liquid-phase hydration of ethylene oxide (EO), whereby a large excess of water (20-25 mol of water/mol of EO) is required for the high conversion of EO and high selectivity for MEG. The concentration of MEG in the final aqueous solution is only approximately 10 wt %, and huge energy is consumed for the distillation of the product from the aqueous solution. As a result, epoxide hydration is one of the most cost-and energy-intensive processes in the chemical industry.Possible catalytic hydration processes have been extensively investigated for the environmentally friendly production of MEG at a low energy cost. Various types of catalysts, including liquid and solid acids or bases, have been explored, such as sulfuric acid, [3] the salts of some acids, [4] cyclic amines, [5] cation-and anion-exchange resins, [6] quaternary phosphonium halides, [7] polymeric organosilane ammonium salts, [8] macrocyclic chelating compounds, [9] and supported metal oxides.[10] However, a high H 2 O/EO molar ratio (i.e. > 10) is still required for high MEG selectivity. The MEG selectivity is very low at low H 2 O/EO molar ratios owing to the formation of diethylene glycol (DEG) and triethylene glycol (TEG) by the self-condensation of MEG, which is readily catalyzed by acid and base catalysts. Moreover, the inherent corrosion and environmental problems associated with the liquid acids/bases limit their application in industry. The development of an efficient and environmentally benign process for the hydration of epoxides with an H 2 O/epoxide molar ratio approaching the stoichiometric value of the chemical reaction is still a huge challenge.In this study, we developed a solid catalyst that is different from the conventional liquid/solid acid or base catalysts for the hydration of epoxides. We constructed the solid catalyst by encapsulating the molecular catalyst [Co III (salen)], with a salen ligand derived from 3,5-di-tert-butylsalicyclaldehyde and trans-1,2-diaminocyclohexane, [11] in the nanocage of the mesoporous silica FDU-12. This catalyst exhibits high activity and selectivity in the hydration of epoxides under mild reaction conditions. Furthermore, the H 2 O/epoxide molar ratio can be decreased to as low as 2:1 while maintaining the conversion of EO above 98 % and the selectivity for MEG above 98 %. This novel catalytic approach has great potential for the green and energy-saving hydration of epoxides, as well as many other conventional chemical reaction processes in industry.The solid catalyst (denoted as FDU-12-[Co III

show abstract

“…Various types of catalysts, including liquid and solid acids or bases, have been explored, such as sulfuric acid, [3] the salts of some acids, [4] cyclic amines, [5] cation-and anion-exchange resins, [6] quaternary phosphonium halides, [7] polymeric organosilane ammonium salts, [8] macrocyclic chelating compounds, [9] and supported metal oxides. [10] However, a high H 2 O/EO molar ratio (i.e.…”

mentioning

confidence: 99%

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors

Li

¹

,

Bai

²

,

Wang

³

et al. 2012

View full text Add to dashboard Cite

Monoethylene glycol (MEG) and 1,2-propylene glycol (PG) are important raw materials for the manufacture of polyester resins, antifreezes, cosmetics, medicines, and other products. [1] The total global demand for MEG has been estimated to be over 19 million metric tons per year.[2] The production of MEG in industry predominantly involves the liquid-phase hydration of ethylene oxide (EO), whereby a large excess of water (20-25 mol of water/mol of EO) is required for the high conversion of EO and high selectivity for MEG. The concentration of MEG in the final aqueous solution is only approximately 10 wt %, and huge energy is consumed for the distillation of the product from the aqueous solution. As a result, epoxide hydration is one of the most cost-and energy-intensive processes in the chemical industry.Possible catalytic hydration processes have been extensively investigated for the environmentally friendly production of MEG at a low energy cost. Various types of catalysts, including liquid and solid acids or bases, have been explored, such as sulfuric acid, [3] the salts of some acids, [4] cyclic amines, [5] cation-and anion-exchange resins, [6] quaternary phosphonium halides, [7] polymeric organosilane ammonium salts, [8] macrocyclic chelating compounds, [9] and supported metal oxides.[10] However, a high H 2 O/EO molar ratio (i.e. > 10) is still required for high MEG selectivity. The MEG selectivity is very low at low H 2 O/EO molar ratios owing to the formation of diethylene glycol (DEG) and triethylene glycol (TEG) by the self-condensation of MEG, which is readily catalyzed by acid and base catalysts. Moreover, the inherent corrosion and environmental problems associated with the liquid acids/bases limit their application in industry. The development of an efficient and environmentally benign process for the hydration of epoxides with an H 2 O/epoxide molar ratio approaching the stoichiometric value of the chemical reaction is still a huge challenge.In this study, we developed a solid catalyst that is different from the conventional liquid/solid acid or base catalysts for the hydration of epoxides. We constructed the solid catalyst by encapsulating the molecular catalyst [Co III (salen)], with a salen ligand derived from 3,5-di-tert-butylsalicyclaldehyde and trans-1,2-diaminocyclohexane, [11] in the nanocage of the mesoporous silica FDU-12. This catalyst exhibits high activity and selectivity in the hydration of epoxides under mild reaction conditions. Furthermore, the H 2 O/epoxide molar ratio can be decreased to as low as 2:1 while maintaining the conversion of EO above 98 % and the selectivity for MEG above 98 %. This novel catalytic approach has great potential for the green and energy-saving hydration of epoxides, as well as many other conventional chemical reaction processes in industry.The solid catalyst (denoted as FDU-12-[Co III

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Investigation of three types of catalysts for the hydration of ethylene oxide (EO) to monoethylene glycol (MEG)

Cited by 58 publications

References 9 publications

Synthesis and characterization of a polymer/multiwalled carbon nanotube composite and its application in the hydration of ethylene oxide

Synthesis and characterization of a polymer/multiwalled carbon nanotube composite and its application in the hydration of ethylene oxide

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors

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Investigation of three types of catalysts for the hydration of ethylene oxide (EO) to monoethylene glycol (MEG)

Cited by 58 publications

References 9 publications

Synthesis and characterization of a polymer/multiwalled carbon nanotube composite and its application in the hydration of ethylene oxide

Synthesis and characterization of a polymer/multiwalled carbon nanotube composite and its application in the hydration of ethylene oxide

Hydration of Epoxides on [CoIII(salen)] Encapsulated in Silica‐Based Nanoreactors

Hydration of Epoxides on [CoIII(salen)] Encapsulated in Silica‐Based Nanoreactors

Contact Info

Product

Resources

About

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors

Hydration of Epoxides on [Co^III(salen)] Encapsulated in Silica‐Based Nanoreactors