Adsorption–desorption characteristics of methyl ethyl ketone with modified activated carbon and inhibition of 2,3-butanediol production

Abstract

Activated carbon (AC) is seldom applied for recovering ketone-based volatile organic compounds because of safety concerns. Adsorption of methyl ethyl ketone (MEK) with AC is a highly exothermic reaction that potentially causes fires in AC beds. Moreover, 2,3-butanediol (BDO) is produced in the desorbed solvent, causing yellowing and odor of the recovered solvent. This study applied a continuous adsorption-desorption apparatus for evaluating the operating capacities and BDO concentration in recovered MEK containing modified and original ACs. AC-1 (TAKETA-G2X) was used as the target for modification. The experimental results indicate that using MgO as the modifier increases the ignition point by 12°C and that applying KNO 3 as the modifier reduces the AC ignition point by 28°C (compared with AC-1). The BDO concentration of the desorbed MEK solvent can be reduced by increasing the loading of the modifying agent (Ethanolamine) (Im-1: 3.1 wt%; Im-5: 6.2 wt%). Moreover, applying the AC pretreated with nitrogen (Im-6) as adsorbent significantly reduces the BDO concentration (from 0.123 wt% to 0.073 wt%). Because desorption and purging procedures were performed in N 2 atmospheres, the BDO concentrations of the desorbed MEK solvents were relatively low and ranged from 0.032 wt% to 0.043 wt%. When the MEK concentration was reduced to 2000 ppm, lower BDO concentrations (0.012-0.022 wt%) were measured in the recovered MEK solvent. The way to modify activated carbon and a better desorbing sequence to effectively inhibit the oxidation of MEK to BDO are developed. The results obtained indicate that the BDO concentration in the desorbed solvent was lower than the original MEK solvent (0.023 wt%). Different approaches can be applied simultaneously to achieve high inhibition effects; however, carbon adsorption performance may be negatively affected.Implications: The study is motivated to improve the quality of recovered solvent and reduce fire hazards, particularly when AC is applied for adsorbing a ketone-based solvent (e.g., MEK). The experimental results indicate that the BDO concentration in the recovered solvent can be reduced and the ignition point of AC can be increased by modifying the AC with an appropriate agent.

Adsorption of Polar Volatile Organic Compounds by a Crystalline Network Structure Based on a Bis(benzimidazole)NiCl2 Complex

“…This phenomenon allowed us to discuss the adsorption/desorption mechanism on the molecular level. This flexible material does not suffer from undesired side reactions that can occur during the adsorption/desorption processes of volatile carbonyl compounds onto/from activated carbon materials . From this perspective, this work proposes an alternative direction for the development of efficient carbonyl adsorbents.…”

“…This flexible material does not suffer from undesired side reactions that can occur during the adsorption/desorption processes of volatile carbonyl compounds onto/from activated carbon materials. 24 From this perspective, this work proposes an alternative direction for the development of efficient carbonyl adsorbents. The substrateselective nature of the adsorption is expected to lead to future comprehensive explorations of this material for use in industrial applications, not only as an adsorbent for polar VOCs, but also as a separation material for processes such as the adsorptive desulfurization of fuels.…”

“…3,23 For example, the adsorption of ketones on activated carbon materials tends to induce oxidation, decomposition, and polymerization reactions. 24 As these reactions are exothermic, the ignition of the activated carbon materials is a concern. To overcome this drawback, the development of state-of-the-art materials that can adsorb ketones without oxidation, decomposition, and polymerization is required.…”

“…Volatile organic compounds (VOCs) are organic compounds that exhibit a high vapor pressure under ambient conditions, such as hydrocarbons, haloalkanes, alcohols, ethers, and carbonyl compounds (e.g., aldehydes, ketones, carboxylic acids, and esters). − Most VOCs are associated with human health issues, including sick-building syndrome, asthma, leukemia, and cancer, as well as environmental phenomena such as stratospheric ozone depletion and photochemical smog formation. − Therefore, the development of efficient technologies to decrease the concentration of VOCs has been the subject of urgent research, with VOC adsorption by porous materials emerging as a promising technique. − Activated carbon materials have been applied industrially for this purpose; however, activated carbon materials exhibit several disadvantages in the adsorption/desorption of volatile carbonyl compounds. , For example, the adsorption of ketones on activated carbon materials tends to induce oxidation, decomposition, and polymerization reactions . As these reactions are exothermic, the ignition of the activated carbon materials is a concern.…”

“…To overcome this drawback, the development of state-of-the-art materials that can adsorb ketones without oxidation, decomposition, and polymerization is required. Moreover, ketones and esters can undergo undesired hydrolysis and oxidation reactions during the thermal desorption from activated carbon materials; the species generated via these side reactions degrade the adsorption efficiency of the activated carbon materials . The development of new materials with smaller energy gaps between their adsorbed and desorbed states may represent a solution to this problem.…”