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Recent Developments in Biorefinery Catalysis
Published in Deniz Uner, Advances in Refining Catalysis, 2017
Elif Ispir Gurbuz, Nazife Işık Semerci
1,3-Propandediol (1,3-PD) is a valuable chemical intermediate used in the production of resins, engine coolants, water-based inks, and most importantly polypropylene terephthalate (PPT), a polyester synthesized from 1,3-PD and teraphthalic acid. The current production of 1,3-PD relies on petroleum derivatives, such as ethylene oxide (through subsequent hydroformylation and HYD) or acrolein (through hydration followed by HYD) (Kraus 2008). Glycerol, being the smallest polyol readily available from biomass, has recently attracted significant attention as a renewable starting feedstock for the production of 1,3-PD. Glycerol is the backbone of triglycerides and thus released as a by-product from biodiesel production in significant amounts (1 kg of glycerol is obtained for every 100 kg of biodiesel) (Behr et al. 2008; Bozell and Petersen 2010). While catalytic conversion of glycerol to various products through different pathways is being investigated, production of 1,3-PD is commercially most interesting due to the existing market (ten Dam and Hanefeld 2011). DuPont recently reported the direct conversion of glycerol to 1,3-PD through fermentation (Emptage et al. 2013); however, this biological process suffers from low metabolic efficiency and poor compatibility with existing infrastructure of the chemical industry (ten Dam and Hanefeld 2011). Many research efforts have therefore been made for the selective production of 1,3-PD from glycerol using heterogeneous catalysts, but many reported attempts resulted in the selective production of 1,2-propandiol (1,2-PD) instead of 1,3-PD (Scheme 10.3), signifying that the transformation of glycerol to 1,3-PD is more challenging. Reaction conditions, as well as metal, acid, and base components of the solid catalysts, have been varied to reach a better understanding of the factors governing the selective reduction of glycerol to 1,3-PD. It has been suggested in many of these studies that the formation of 1,3-PD goes through the intermediate formation of 3-hydroxypropanal. This species is obtained by the endothermic elimination of the secondary alcohol group of glycerol, followed by a tautomerization reaction. This aldehyde species is then hydrogenated in an exothermic step to form the 1,3-PD species (ten Dam and Hanefeld 2011; Ruppert et al. 2012; Besson et al. 2014).
Chemical characterization of nanoparticles and volatiles present in mainstream hookah smoke
Published in Aerosol Science and Technology, 2019
Véronique Perraud, Michael J. Lawler, Kurtis T. Malecha, Rebecca M. Johnson, David A. Herman, Norbert Staimer, Michael T. Kleinman, Sergey A. Nizkorodov, James N. Smith
Mass spectra from control experiments, which include experiments performed without any tobacco (charcoal + water only), with the conventional tobacco but no charcoal (no heat) and only glycerol (replacing the tobacco) are given in SI Figure S8. The major common ions (nominal m/z 43, 45, 57, 61, and 75) observed in the waterpipe mainstream smoke were common to all spectra, including that of glycerol (propane-1,2,3-triol). Upon thermal decomposition, glycerol has been reported to form not only two major products, namely acetaldehyde (C2H4O, MW = 44 g mol−1) and acrolein (C3H4O, MW = 56 g mol−1), but also 3-hydroxypropanal (C3H6O2, MW = 74 g mol−1), 1-hydroxypropan-2-one (C3H6O2, MW = 74 g mol−1), hydroxyacetone (or acetol; C3H6O2, MW = 74 g mol−1), glycolaldehyde (C2H4O2, MW = 60 g mol−1), and acetic acid (C2H4O2, MW = 60 g mol−1) (Corma et al. 2008; Hemings et al. 2012; Jensen, Strongin, and Peyton 2017; Katryniok et al. 2010; Martinuzzi et al. 2014; Nimlos et al. 2006). Ionization of these compounds in the PTR-ToF-MS ion source would give the observed [M + H]+ ions. Both acetic acid and glycolaldehyde are known to fragment under typical PTR-MS conditions such as the ones applied here, to give an additional fragment at m/z 43.018 (C2H3O+) (Baasandorj et al. 2015). Though, acetic acid is thought to be formed from secondary oxidation process (Jensen, Strongin, and Peyton 2017; Katryniok et al. 2010), it is more likely that the peaks at m/z 61/43 are due to glycolaldehyde instead. Further evidence for this assignment is the presence of a minor peak at m/z 91.039 attributed to glyceraldehyde (SI Figure S7), which was previously proposed as an intermediate in the decomposition process of glycerol leading to glycolaldehyde. (Jensen, Strongin, and Peyton 2017).