Size of this PNG preview of this SVG file: Add a one-line explanation of what this file represents, (SVG file, nominally 325 × 83 pixels, file size: 38 KB), EliminationReactionGlycerol2Acrolein2.svg, https://creativecommons.org/licenses/by-sa/3.0, Creative Commons Attribution-Share Alike 3.0, Creative Commons Attribution-ShareAlike 3.0 Unported, GNU Free Documentation License, version 1.2 or later, https://commons.wikimedia.org/w/index.php?title=File:EliminationReactionGlycerol2Acrolein2.svg&oldid=511160474, Files moved from en.wikipedia to Commons requiring review as of 11 May 2009, Creative Commons Attribution-ShareAlike License, Permission is granted to copy, distribute and/or modify this document under the terms of the, {{BotMoveToCommons|en.wikipedia|year={{subst:CURRENTYEAR}}|month={{subst:CURRENTMONTHNAME}}|day={{subst:CURRENTDAY}}}} {{Information |Description={{en|Glycerol to acrolein reaction}} |Source=Transferred from [http://en.wikipedia.org en.wikipedia]; transf. Nanoporous Catalysts for Biomass Conversion. The dioxane and dioxolane derivatives in the aqueous phase and the ring‐structured chemicals in the oil phase have rarely been reported for glycerol dehydration in gas‐phase or sub‐ and supercritical water, indicating the special role of SC‐CO2 in removing these coke precursors from the catalyst bed. Number of times cited according to CrossRef: Glycerol adsorption and mechanism of dehydration to acrolein over TiO2 surface: A density functional theory study. Influence of reaction parameters on glycerol dehydration over HZSM-5 catalyst. Original file (SVG file, nominally 325 × 83 pixels, file size: 38 KB), https://creativecommons.org/licenses/by-sa/3.0 It is reasoned that the Brønsted acid sites, which favored acrolein formation, also led to faster coking kinetics, whereas the coking and decoking by SC‐CO2 at Lewis acid sites reached equilibrium. Extensive efforts have been committed in recent years to improve glycerol dehydration to acrolein, 1b, 2 including glycerol conversion in sub‐ and supercritical water, 3 as well as selective gas‐phase conversion. The reactant glycerol could be in both the vapor and liquid phases at 320 °C and 8 MPa. Supercritical carbon dioxide (SC‐CO2) has been used for the first time as a reaction medium for the dehydration of glycerol to acrolein catalyzed by a solid acid. This work aimed to study the selectivity control over Cs 2.5 H 0.5 PW 12 O 40 /Nb 2 O 5 (CsPW‐Nb). Glycerol conversion and yields of acrolein and acetol with TOS over HZSM‐5 in SC‐CO2 reaction system in comparison with those in gas‐phase CO2. This reaction system allows better heat and mass transfer than fixed-bed reactors, along with the possibility of performing continuous regeneration if needed. Click on a date/time to view the file as it appeared at that time. [a] For fair comparison, this is normalized based on per 10 g of glycerol input over the entire TOS (wt % per 10 g glycerol), determined by thermogravimetric analysis (Figure SI3). Auteur: V8rik : Conditions d’utilisation. Analyzing the reaction products offered more insights into the SC‐CO2 system. After depressurization through a back pressure regulator, the reaction effluent flew through a condenser with circulating coolant at 0 °C and the condensed liquid product was collected. English: Glycerol to acrolein reaction. Learn about our remote access options, Department of Biosystems Engineering & Soil Science, The University of Tennessee, 2506 E. J. Chapman Drive, Knoxville, TN, 37996 USA. Copyright © 2020 Elsevier B.V. or its licensors or contributors. A renewable material such as glycerol is an attractive alternative for acrolein production. Details of the glycerol conversion and yields of acrolein and acetol against TOS are given in Figure 1. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Dehydration of glycerol to acrolein was performed on WO 3 /TiO 2 catalysts in a continuous flow fixed bed reactor. Efforts were also made to probe the coking mechanism on the zeolite performing in supercritical carbon dioxide (SC‐CO2) medium. The main process variables are the reaction temperature, the concentration of glycerol in water, and the space velocity in fixed-bed reactors. Working off-campus? Although glycerol does not dissolve well in SC‐CO2,11a the major reaction product of acrolein, which is also considered as a coke precursor,1b is soluble in the highly diffusive SC‐CO2,14 and is thus quickly moved out of the catalyst bed, preventing it from further secondary reactions that lead to decomposition and coking. ► Dehydration of glycerol to acrolein over WO3/TiO2 catalysts performed with high yields. By continuing you agree to the use of cookies. Creative Commons Attribution-Share Alike 3.0 Although coking is not totally avoidable, there appeared to be a subtle equilibrium between coking and decoking by SC‐CO2 that could be achieved by tuning the catalyst properties and process conditions for a better acrolein yield and longer catalyst life. In light of the surplus of glycerol resulting from massive global biodiesel production, acrolein, the simplest unsaturated aldehyde that can be derived by glycerol dehydration, has received much research attention.1 Conjugation of the carbonyl group with the vinyl group renders acrolein a versatile intermediate for the synthesis of an array of high‐value chemicals such as methionine and acrylic acid.1b Commercially, acrolein is produced through the oxidation of propylene, based on fossil fuels. All structured data from the file and property namespaces is available under the. Nonetheless, our system still achieved a longer TOS and lower rate of coking than in previously reported studies. Shifting the raw material from propylene to glycerol would not only sustain commercial development for the biodiesel value chain, but also reduce net emissions from fossil fuels. Learn more. Further analysis of the liquid product by inductively coupled plasma optical emission spectroscopy (ICP‐OES) detected no obvious leaching from the zeolite. . The acrolein selectivity in dehydration of glycerol was affected by reaction temperature, oxygen co‐feeding, and glycerol concentration. In Run‐P, we had to stop the CO2 flow and the feed of glycerol solution (but not the heaters) around every 200 h of TOS for roughly 5 minutes to change an exhausted CO2 cylinder. The non‐condensable gaseous product was sampled by using a gas syringe through the sampling port. The catalytic dehydration of glycerol to acrolein is a very attractive alternative to the propylene‐based process, due to the future exhaustion of fossil feedstocks and the increasing production of biomass‐based glycerol. However, despite their initial good performance, few solid acid catalysts are known to maintain their catalytic activity long enough for practical application without need for regeneration, as the high functionality of glycerol leads to severe coking on the catalysts. If you do not receive an email within 10 minutes, your email address may not be registered, Fluid phase equilibria offer insight into the reaction mechanism and kinetics, but, to our knowledge, neither theoretical modeling nor experimentally verified equilibrium data concerning the ternary mixture C3H8O3/H2O/CO2 have been reported to date. Coproduction of Acrylic Acid with a Biodiesel Plant Using CO2 as Reaction Medium: Process Modeling and Production Cost Estimation. We speculate that our SC‐CO2 reaction system is a classical multiphase trickle‐bed reactor and that glycerol conversion mainly occurred in the liquid phase. Learn more. Our characterization of the catalyst by using infrared pyridine adsorption (Py‐FTIR, Figure 2 a) and NH3‐TPD (Table SI1 and Figure SI2) revealed that the HZSM‐5 had predominantly Brønsted acid sites (except for the non‐distinguishable region of B+L acid sites at 1486 cm−1) and moderate distribution of each of weak, medium, and strong acid sites.
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