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The bioconversion of cellulose and the transformation of glycerol can yield various diols, aligning with environmental sustainability goals by reducing dependence on fossil fuels, lowering raw material costs, and promoting sustainable development. However, in the selective hydrogenolysis of glycerol to ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG), challenges such as low selectivity of catalytic systems, poor stability, limited renewability, and stringent reaction conditions remain. The production of diols from cellulose involves multiple reaction steps, including hydrolysis, isomerization, retro-aldol condensation, hydrogenation, and dehydration. Consequently, the design of highly efficient catalysts with multifunctional active sites tailored to these specific reaction steps remains a significant challenge. This review aims to provide a comprehensive overview of the selective regulation of catalysts for producing EG and 1,2-PG from cellulose and glycerol. It discusses the reaction pathways, process methodologies, catalytic systems, and the performance of catalysts, focusing on active site characteristics. By summarizing the latest research in this field, we aim to offer a detailed understanding of the state-of-the-art in glycerol and cellulose conversion to diols and provide valuable guidance for future research and industrial applications. Through this review, we seek to clarify the current advancements and selective control strategies in diol production from glycerol or cellulose, thereby offering critical insights for future investigations and industrial scale-up. [ABSTRACT FROM AUTHOR]

BACKGROUND: The production of value‐added chemicals from pyrolysis oil or its fractions is of great significance for the valorization of biomass. Diols, including ethylene glycol (EG) and 1,2‐propylene glycol (1,2‐PG), are important bulk chemicals with widespread industrial applications. Here we investigated the production of diols from pyrolysis oil water‐soluble fraction (WS) using a hybrid catalyst (Ni + H2WO4). RESULTS: Firstly, levoglucosan, glycolaldehyde and acetol, three main components in WS, were respectively selected as the single model compound, and their respective conversions into diols were investigated at different temperatures for different reaction times. The result showed the optimum reaction temperature and time were 180 °C and 2 h respectively, under which a EG yield of 53.8% and 1,2‐PG yield of 5.2% were obtained from levoglucosan conversion, a EG yield of 98.6% was obtained from glycolaldehyde conversion, and a 1,2‐PG yield of 98.5% was obtained from acetol conversion. The reaction pathway of levoglucosan conversion was analyzed. Secondly, the model mixture of levoglucosan, glycolaldehyde and acetol was used to simulate the real WS, and their conversion was investigated at different ratios of H2WO4 to Ni. The result showed the optimum catalyst composition was 0.15 g H2WO4 and 0.3 g Ni, under which a EG yield of 76.4% and 1,2‐PG yield of 38.4% were obtained. Thirdly, the real original WS was converted under the optimum reaction conditions and the result only gave a EG yield of 19.1% and 1,2‐PG yield of 25.8% (based on the carbon moles of main substrates), which were much less than the two yields of model mixture. That was related to the presences of other types of chemicals in original WS. After the original WS being adsorbed by activated carbon, the yields of EG and 1,2‐PG could be increased to 39.2% and 37.9%, respectively. CONCLUSION: The presences of certain other types of chemicals (such as acids, furans, phenolics and cyclopentanones) in original WS inhibited the production of diols. The activated carbon adsorption could efficiently remove most of furans, phenolics and cyclopentanones in original WS and increased significantly the diols yields. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Research on the use of biomass resources for the generation of energy and chemical compounds is of great interest worldwide. The development and growth of the biodiesel industry has led to a parallel market for the supply of glycerol, its main by-product. Its wide availability and relatively low cost as a raw material make glycerol a basic component for obtaining various chemical products and allows for the development of a biorefinery around biodiesel plants, through the technological integration of different production processes. This work proposes a review of one of the reactions of interest in the biorefinery environment: the hydrogenolysis of glycerol to 1,2-propylene glycol. The article reviews more than 300 references, covering literature from about 20 years, focusing on the heterogeneous catalysts used for the production of glycol. In this sense, from about 175 catalysts, between bulk and supported ones, were revised and discussed critically, based on noble metals, such as Ru, Pt, Pd, and non-noble metals as Cu, Ni, Co, both in liquid (2–10 MPa, 120–260 °C) and vapor phase (0.1 MPa, 200–300 °C). Then, the effect of the main operational and decision variables, such as temperature, pressure, catalyst/glycerol mass ratio, space velocity, and H2 flow, are discussed, depending on the reactors employed. Finally, the formulation of several kinetic models and stability studies are presented, discussing the main deactivation mechanisms of the catalytic systems such as coking, leaching, and sintering, and the presence of impurities in the glycerol feed. It is expected that this work will serve as a tool for the development of more efficient catalytic materials and processes towards the future projection of glycerol biorefineries. [ABSTRACT FROM AUTHOR]

In this study, the density and surface tension of binary mixtures of 1,2-propylene glycol (1) + glycerol (2) at the temperature range of 303.15 K to 393.15 K under atmospheric pressure are reported. In addition, the excess molar volume, surface tension deviation, molar volume and molar thermal expansion of the mixture were calculated. Finally, the Jouyban–Acree model was used to correlate the experimental data mathematically, and the accuracy of the model was verified by using the mean relative deviation (MRD). The results showed that the MRD between the experimental data and the calculated data of density and surface tension were 0.003 ± 0.007 and 0.023 ± 0.092, respectively. The accuracy of the model is high and can be directly applied to the production and application of some pharmaceutical and liquid industrial products. [ABSTRACT FROM AUTHOR]

In order to study the influence of ratio and amount of smoke producing agent on the release characteristics of the heated cigarette smoke aerosol, a series of heated cigarettes with different mass ratio and amount of glycerol (GL)/1,2-propylene glycol(PG) were prepared. The cigarette was sucked by the smoking machine and the aerosol was collected puff-by-puff, then the release of aerosol collected mass, PG, GL and nicotine in different heated cigarette samples were detected and analyzed. The results showed that when the total amount of GL/PG was 20% (mass fraction), with the GL/PG mass ratio decreasing from 95/5 to 50/50, the puff-by-puff release quantity of PG increased and the increase trend of total PG release quantity was more obvious, the puff-by-puff release quantity of GL decreased and the decrease trend of total GL release quantity was more obvious, and the puff-by-puff release quantity of nicotine decreased and the total release decreased linearly. The GL/PG mass ratio of smoke producing agent was basically linearly correlated with the GL/PG mass ratio in aerosol. When the mass ratio of GL/PG was fixed at 80/20, with the total addition amount increased from 0% to 25%, the release quantity of PG and GL increased, and the stability of puff-by-puff release decreased; when the total addition amount was more than 10%, the puff-by-puff quantity of aerosol collected mass increased significantly, and the release quantity of nicotine changed slightly. The total addition amount of GL/PG in heated cigarette had no significant effect on the GL/PG mass ratio in aerosol. [ABSTRACT FROM AUTHOR]

Glycerol hydrogenolysis to 1,2‐propylene glycol in a continuous down‐flow fixed‐bed reactor with 60 %Cu/Al2O3 catalyst was investigated. The routes of main, intermediate and by‐products formation were proposed. It is shown that an increase in the catalyst particle size from 0.1–0.16 to 1.6–2.5 mm transfers the process from the kinetic mode to an intermediate mode between the kinetic and internal diffusion controlled reaction rate. In this case, the observed activation energy decreased by 30 %. The optimal conditions for the process have been determined. [ABSTRACT FROM AUTHOR]

Enantiomers of 1,2-Propylene glycol (1,2-PG) were investigated in 64 commercial Chinese Baijiu including soy sauce aroma-type Baijiu (SSB), strong aroma-type Baijiu (STB), and light aroma-type Baijiu (LTB), via chiral gas chromatography (β-cyclodextrin). The natural enantiomeric distribution and concentration of 1,2-PG in various baijiu were studied to evaluate whether the distribution and content of the two isomers of 1,2-PG were correlated with the aroma type and storage year. The results showed that 1,2-PG has a high enantiomeric ratio and the (S)-configuration predominated in SSB. The average S/R enantiomeric ratio of this compound in SSB was approximately 87:13 (±3.17), with an average concentration of 52.77 (±23.70) mg/L for the (S)-configuration and 8.72 (±3.63) mg/L for the (R)-enantiomer. The (R)-configuration was predominant in the STB, whereas neither (S) nor (R)-form of 1,2-PG were detected in LTB. The content of the two configurations of 1,2-PG in the JSHSJ vintage of SSB showed a wave variation, with an average S/R enantiomeric ratio of 89:11 (±1.15). The concentration of (R)-1,2-PG in XJCTJ vintage liquors showed an upward and then downward trend with aging time, with an overall downward trend, and the concentration of (S)-form showed a wavy change with an overall upward trend. Except for the LZLJ-2019 vintage where both (R) and (S)-1,2-PG were present, all other samples only existed (R)-form, and a decreasing trend of (R)-enantiomer with aging time was observed. The enantiomeric ratio of 1,2-PG might be one of the potential markers for adulteration control of Baijiu as industrial 1,2-PG usually presented in the racemic mixture. Sensory analysis revealed olfactory thresholds of 4.66 mg/L and 23.92 mg/L for the (R)- and (S)-configurations in pure water respectively. GC-O showed both enantiomers exhibited different aromatic nuances. [ABSTRACT FROM AUTHOR]

Copyright of Tobacco Science & Technology is the property of Tobacco Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The correlation between the physico-chemical properties of bare and Mo-doped nickel aluminate derived catalysts and product distribution during hydrogenolysis of glycerol with in situ produced hydrogen in continuous was investigated. Stoichiometric nickel aluminate spinel was synthesized via citrate sol-gel in a one-pot synthesis and subsequently doped it with 1 wt% Mo, using both sol-gel one-pot and impregnation methods. Catalytic runs were performed at 235 ºC/ 45 bar for 4 h TOS. The results indicate that Mo-doping increased the number of both metal and acid sites, leading to more selectivity towards deoxygenated products. 1,2-propylene glycol was the major liquid product, Mo/NiAl catalyst exhibited the highest yield (27%) and selectivity (39%). Post-reaction characterization revealed that leaching and oxidation of metals could potentially cause catalyst deactivation. 1 wt% Mo-doped nickel aluminate-derived catalysts possess potential for the selective production of 1,2-PG in a eco-friendly process through one-pot coupling H 2 generation and hydrogenolysis reactions. [Display omitted] • NiAl 2 O 4 is doped with 1 wt% Mo using both sol-gel and impregnation methods. • Catalysts are evaluated for 1,2-PG production via H 2 -free glycerol HDO. • Mo doping hinders Ni reducibility and increases the metal and acid sites densities. • Mo/NiAl catalyst achieves X Gly = 69%, Y 1,2-PG = 27% and S 1,2-PG = 39%. • Negligible deactivation is observed throughout the four-hour reaction duration. [ABSTRACT FROM AUTHOR]

It is shown that the reaction of the hydrolysis–hydrogenolysis of cellulose to alcohols can be catalyzed by the binary system Ca(OH)2–composite material based on tungsten carbides W2C/WC, obtained by combining mechanochemical activation and self-propagating high-temperature synthesis with an exothermic mixture of tungsten oxide, metallic magnesium, and technical carbon. It is demonstrated that the amounts of tungsten carbides (W2C, WC) and the ratio between them can be controlled by introducing inert additives (metallic tungsten or calcium carbonate) to the exothermic mixture. The order of introducing reagents to the exothermic mixture and their activation is found to affect the textural properties of the materials. Self-propagating high-temperature synthesis is shown to be superior to mechanochemical activation. The catalytic properties of these materials are studied in the hydrolysis–hydrogenolysis of cellulose. It is determined that the phase composition of the composite materials affects the yields of ethylene glycol and 1,2-polyethylene glycol and their ratio. The maximum total yield of the glycols (25–31%) is obtained using a sample with a high W2C content. [ABSTRACT FROM AUTHOR]

The features of the liquid-phase hydrogenolysis of glycerol to 1,2-propylene glycol over Cu/Al2O3 catalysts (Cu = 2–80 wt %) and individual copper particles have been studied. It has been shown that the main factor determining the activity of the catalysts is the specific surface area of copper. It has been found that the Cu/Al2O3 catalyst containing 60 wt % Cu is the most efficient. A new reaction mechanism is proposed based on the obtained data. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: The conversion of fructose to 1,2‐propylene glycol (PG) is an important process from cellulosic biomass to high‐value added chemicals. Herein, Ru‐WOx/hydroxyapatite (HAP) catalyst was employed for this reaction and reached up to 91.3% yield of PG at 180 °C, 1 MPa initial hydrogen for 8 h in water. On this catalyst, Ru and WOx were highly dispersed on HAP support and they interacted with each other to form a special catalytic center. The lack of isolated Ru or RuW alloy site led to a moderate activity for hydrogenolysis and hindered the further conversion of PG to propanol. The weak basic HAP support efficiently prevented the humin formation. This precisely controlled catalyst has potential in green PG production. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: The conversion of fructose to 1,2‐propylene glycol (PG) is an important process from cellulosic biomass to high‐value added chemicals. Herein, Ru‐WOx/hydroxyapatite (HAP) catalyst was employed for this reaction and reached up to 91.3% yield of PG at 180 °C, 1 MPa initial hydrogen for 8 h in water. On this catalyst, Ru and WOx were highly dispersed on HAP support and they interacted with each other to form a special catalytic center. The lack of isolated Ru or RuW alloy site led to a moderate activity for hydrogenolysis and hindered the further conversion of PG to propanol. The weak basic HAP support efficiently prevented the humin formation. This precisely controlled catalyst has potential in green PG production. [ABSTRACT FROM AUTHOR]

Copyright of Tobacco Science & Technology is the property of Tobacco Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The kinetics of hydrogenolysis of glycerol to 1,2-propylene glycol on a catalyst containing 60 wt % copper on Al2O3 was studied. A reaction scheme for the conversion of glycerol under conditions of catalytic hydrogenolysis was proposed. The forms of kinetic equations for the consumption of glycerol in the main direction to acetol and 1,2-propylene glycol and in side conversion into ethylene glycol were determined. It was found that both of the reactions of glycerol hydrogenolysis have zero and first orders with respect to hydrogen and glycerol, respectively. The apparent activation energies of the main (to acetol and 1,2-propylene glycol) and side (to ethylene glycol) reactions of glycerol conversion are 125 500 ± 200 and 87 500 ± 500 J/mol, respectively. The assumption that the dehydration of glycerol to acetol is a rate-limiting step of the production of 1,2-propylene glycol was substantiated. [ABSTRACT FROM AUTHOR]

Copyright of China Surfactant Detergent & Cosmetics (1001-1803) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphical abstract Concentrated glucose were efficiently converted to 1,2-propylene glycol (1,2-PG) and ethylene glycol (EG) over RuSn/AC catalysts in a semi-continuous autoclave reactor. The yield of 1,2-PG and EG reached 25% and 26.9%, respectively, with the glycols productivity of nearly 180 g L−1 h−1 in the conversion of 10% glucose at 513 K for 10 min. The tin loading greatly affected the catalyst structure and its catalytic performances. At a suitable tin loading, i.e., 5%Ru3%Sn/AC, 23% of tin was present as highly dispersed Sn4+ with 77% of tin forming RuSn alloys under reaction conditions, affording the balanced rates of sugar isomerization, retro-aldol condensation and hydrogenation reactions to get a high yield of glycols. Highlights • Concentrated sugars were efficiently converted to 1,2-propylene glycol and ethylene glycol over 5%Ru3%Sn/AC catalysts. • The yield of 1,2-PG and EG reached 25% and 26.9%, respectively, with 180 g L−1 h−1 glycols productivity. • The tin loading greatly affected the structure of catalyst and its catalytic performance. • The dispersed SnO 2 catalyzed isomerization and RuSn alloys played the major roles in catalytic retro-aldol condensation. Abstract A series of RuSn/AC catalysts with 5% Ru and 1–6% Sn loadings were synthesized for converting concentrated (10 wt%) sugars to 1,2-propylene glycol (1,2-PG) and ethylene glycol (EG) in a semi-continuous autoclave reactor. The catalysts structure and the product distributions are found to be highly dependent on the tin loading. At tin contents below 2%, RuSn alloy was formed coexisting with small amounts of highly dispersed SnO 2 in the catalyst, and hexitols were the main products due to the high activity of catalysts for hydrogenation. At a tin content above 5%, more SnO 2 species were present and covered RuSn alloy particles, leading to notable amounts of humins in the reaction due to the depressed hydrogenation activity. As for the optimal catalyst of 5%Ru3%Sn/AC, 77% of tin formed RuSn alloy with ruthenium and 23% of tin existed in the form of highly dispersed SnO 2 under reaction conditions. The catalyst gave 25% and 26.9% yields of 1,2-PG and EG in the glucose conversion at 513 K for 10 min. The glycols yield was insensitive to the feeding rate of glucose, which could be increased to 10 mL/min with a glycols productivity of nearly 180 g L−1 h−1. The catalysts structure and reaction networks were proposed according to pseudo in situ characterizations and conditional experiments. The highly dispersed SnO 2 was effective to sugar isomerization and the RuSn alloy played the major role in retro-aldol condensation and hydrogenation reactions. Over the 5%Ru3%Sn/AC catalyst, the rates of cascade reactions of isomerization, retro-aldol condensation and hydrogenation matched well due to the balanced activity of RuSn alloy and highly dispersed SnO 2 , which afforded a high yield of 1,2-PG and EG. [ABSTRACT FROM AUTHOR]

Hydrogenolysis of glycerol to 1,2-propylene glycol at 200°C in the presence of Cu/Al2O3 catalysts prepared by coprecipitation from copper nitrate and aluminum nitrate using NaOH and NH4OH has been studied. The kinetics of the reaction is described by the first-order rate law. It has been found that the selectivity for the target product for all catalyst samples is 98% and the activity of the catalysts depends on their synthesis conditions. By using X-ray diffraction analysis, transmission electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, it has been revealed that the active phase of Cu/Al2O3 samples is made of particles with an average size of 20 to 140 nm, whose surface consisted of CuO and Cu2O. The catalysts with different particle sizes the active phase but close chemical composition exhibits comparable activity (67.5 ± 5 h-1mol--1). This finding indicates that the hydrogenolysis reaction run in the presence of Cu/Al2O3 is not structure-responsive. A decrease in concentration of the Cu2O phase of the catalyst leads to a decrease in the hydrogenolysis rate, thereby this indicating a higher activity of the Cu2O phase in comparison with the CuO phase. [ABSTRACT FROM AUTHOR]

Ru clusters and sulfoacids are isolated in a yolk-shell nanoreactor to balance hydrolysis, isomerization, hydrogenolysis and hydrogenation well, yielding 38% of 1,2-propylene glycol from cellulose valorization, corresponding to a high productivity of 342.86 mol/h g Ru –1 and a large TON of 173264. [Display omitted] • Isolated Ru clusters and sulfoacids are integrated in a yolk-shell nanoreactor. • Cellulose hydrogenolysis to 1,2-propylene glycol with 38% yield. • High productivity of 342.86 mol 1,2-PG h−1 g Ru –1 and turnover number of 173264. • Enhanced metal-acid synergism, diffusion pathway and optimized acidity/basicity. • Intermediate reactions are banlanced to render high yield 1,2-propylene glycol. Direct conversion of cellulose to high yield 1,2-propylene glycol (1,2-PG) is amazing in the biomass valorization to diols, since this process is atom-economic, carbon neutral, and the produced 1,2-PG has a large market demand. However, it is very challenging to control cellulose hydrogenolysis owing to high reactivity of intermediates (like glucose) and metal-acid repelling, leading to decreased selectivity of metal-acid multi-functional catalysts. Aimed at this, we herein developed a highly selective metal-acid catalyst (Ru/NC@void@MC-SO 3 H) with site isolated Ru clusters (1.4 nm) on the core and sulfoacids on the shell in a yolk-shell nanoreactor by a layer-by-layer assembly before chemical transformation. The spatial isolation of metal and acid sites integrated in a mesoporous yolk-shell nanoreactor not only facilitates the metal-acid synergism in hydrolysis, isomerization/hydrogenolysis and hydrogenation cascade reactions, but also provides a designated diffusion pathway that is favorable for reaction species. As expected, the elaborately fabricated Ru/NC@void@MC-SO 3 H proves to be highly selective to 1,2- PG (38 % yield), delivering a productivity of 342.86 mol h−1 g Ru –1 and an extremely high turnover number of 173264, outperforming the state-of-art metal-acid catalysts for cellulose hydrogenolysis to 1,2-PG. Our characterization and performance test suggest that sulfoacids are mainly responsible for cellulose hydrolysis, while N -stabilized Ru centers contribute to the glucose isomerization to fructose and its further hydrogenolysis to dihydroxyacetone, followed by hydrogenation to 1,2-PG on metallic Ru species. The acidity and basicity optimized for site isolated Ru/NC@void@MC-SO 3 H is beneficial to balance intermediate reactions, rendering a higher selectivity to target 1,2-PG. The concept illustrated in this study will provide a guide for the development of other site isolated multi- functional catalysts towards cellulosic biomass conversion and other cascade reactions. [ABSTRACT FROM AUTHOR]

Experimental solubility, acid-dissociation constants (pKa) and activity coefficient data have been compiled from the published pharmaceutical and chemical literature for neutral organic molecules and ionic species dissolved in anhydrous 1,2-propylene glycol. The compiled experimental data were transformed into molar solubility ratios, water-to-anhydrous propylene glycol (P) and gas-to-anhydrous propylene glycol (K) using standard thermodynamic relationships. The derived Abraham model correlations described the observed solubility and partition coefficient data of neutral organic compounds and ionic species to within 0.18 log units and 0.18 log units (or less), respectively. [ABSTRACT FROM PUBLISHER]

The multiple thermal decomposition mechanisms of 1,2-propylene glycol are studied through theoretical calculation and experiment, including carbon chain break, dehydrogenation and dehydration mechanism. The wavefunction is employed to analyze the decomposition process from a micro perspective. DLPNO-CCSD(T)/CBS method is engaged in establishing potential energy surface. The results reveal that the dehydration and carbon chain break mechanism are the primary pyrolysis paths, and the former is the dominant pyrolysis mechanism at low temperature, while the latter is applicable at the high temperature. The pyrolysis products are mainly acetaldehyde, propanal and acetone, which is consistent with experimental results. Besides, the comparison results of 1,2-propylene glycol and glycerol pyrolysis products indicate that the increment of hydroxyls are conducive to the generation of carbonyl compounds during the polyol thermal decomposition. This work is aimed to comprehensively investigate the pyrolysis mechanism of 1,2-propylene glycol and provide the valuable thermodynamics and kinetic data for developing efficient polyol pyrolysis technology. Furthermore, it provides a reference for choosing low-toxic tobacco humectant. Pyrolysis mechanism of 1,2-propylene glycol is investigated by theoretical calculation, pyrolysis experiment and wavefunction analysis, and the effect of hydroxyl on the polyol pyrolysis product is explored. [Display omitted] • The combination of quantum chemistry calculation and experiment. • The application of Interaction Region Indicator (IRI), Localized Orbital Locator (LOL) and Mayer bond order (MBO). • Comparison with the pyrolysis products of glycerol. • Providing the valuable thermodynamics and kinetics data for developing efficient polyol pyrolysis technology. [ABSTRACT FROM AUTHOR]

A novel and efficient process for the production of 1,2-propylene glycol with high productivity and high selectivity from biomass-derived lactic acid over CuO was investigated. As a result, CuO exhibited a high catalytic activity while Zn acted as a reductant for the conversion of lactic acid to 1,2-propylene glycol. Among the various reaction parameters, such as catalysts, reductants, temperature, water filling and reaction time we investigated, a 93% yield of 1,2-propylene glycol in the presence of 0.83 mmol lactic acid, 5 mmol CuO and 30 mmol Zn with 35% water filling at 250 °C for 2 h was achieved. In addition, a carbon balance at optimum reaction conditions by TOC indicated that approximately 99% lactic acid was converted into liquid products in the transformation. In situ formed hydrogen by the oxidation of Zn in water is effective for the transformation compared to added gases hydrogen. The proposed mechanism for the conversion of lactic acid to 1,2-propylene glycol over CuO is also discussed. [ABSTRACT FROM AUTHOR]

The solubilities, densities, and refractive index data for the 1,2-propylene glycol + MNO3 + H2O (M = Na, K, Rb, Cs) ternary systems at 25° and 35°C were measured with mass fractions of 1,2-propylene glycol ranging from 0 to 1.0. In all cases, the presence of 1,2-propylene glycol significantly reduces the solubility of the salts in aqueous solution. The experimental data of density, refractive index, and solubility of saturated solutions for these systems were correlated using polynomial equations. Furthermore, the refractive index and density of unsaturated ternary solutions were also determined and correlated with the salt concentrations and proportions of 1,2-propylene glycol in the systems. [ABSTRACT FROM PUBLISHER]

Integral enthalpies of dissolution Δ H of L-cysteine in mixtures of water with glycerol, ethylene glycol, and 1,2-propylene glycol at concentrations of organic solvents of up to 0.37 mole fraction were measured by calorimetry of dissolution. The standard values of the dissolution enthalpies (Δ H°) and the transfer enthalpies (Δ H°) of amino acid from water to the mixed solvent were calculated. It was shown that the calculated enthalpic coefficients of the pair interactions of L-cysteine with cosolvent molecules have positive values. The obtained data are interpreted from the viewpoint of the prevalence of different types of interactions in the solutions and influence of the cosolvents nature on the thermochemical characteristics of amino acid dissolution. [ABSTRACT FROM AUTHOR]

Abstract: Various copper chromite catalysts with and without promoters were prepared by simultaneous co-precipitation and digestion technique and the role of promoters (Al, Ba and Zn) was investigated for hydrogenolysis of glycerol to 1,2-propylene glycol (1,2-PG) in both batch and continuous operations. Among various promoters studied, copper chromite catalyst with Ba as a promoter showed the highest activity and selectivity of 85% to 1,2-PG. This catalyst was found to be active for more than 800h in a continuous operation also. Ammonia TPD results showed that barium promoted copper chromite catalyst had the highest acidity which facilitates the dehydration of glycerol to acetol which is the first step in hydrogenolysis of glycerol to 1,2-PG. The effect of barium content and variation in the promoters combination was also studied. [Copyright &y& Elsevier]

Abstract: This work reports solubility data of methane and carbon dioxide in 1,2-propylene glycol and the Henry''s law constant of each solute in the studied solvent at saturation pressure. The measurements were performed at 303, 323, 373, 398 and 423.15K and pressures up to 4.5MPa for carbon dioxide solubility and pressures up to 12.1MPa for methane solubility. The experiments were performed in an autoclave type phase equilibrium apparatus using the total pressure method (synthetic method). All investigated systems show an increase of gas-solubility with the increase of pressure. A decrease of carbon dioxide solubility with the increase of temperature and an increase of methane solubility with the increase of temperature was observed. From the variation of solubility with temperature, partial molar enthalpy and entropy change of the solute for each mixture were calculated. [Copyright &y& Elsevier]

Abstract: Aggregation of tetradecyltrimethylammonium bromide, TTAB, in mixed solvent systems containing ethylene glycol, EG, 1,2-propylene glycol, 1,2-PROP, 1,3-propylene glycol, 1,3-PROP, and tetraethylene glycol, TEG, has been investigated by employing conductivity and fluorescence methods. Gibbs energies of micellization were determined in order to evaluate the effects of the co-solvent on the aggregation process. Information about the influence of the organic solvent on the surfactant adsorption at the air-solution interface, on the micellar size and on the polarity of the micellar interfacial region was obtained by means of surface tension and fluorescence measurements. The study of the reaction methyl naphthalene-2-sulfonate+ in the water–glycol TTAB micellar solutions provided information about the characteristics of TTAB micelles as microreactors in the water–solvent binary mixtures. [Copyright &y& Elsevier]

In the several publications reviewed in this article, propylene glycol (PG; 1,2-propylene glycol) is described as a very weak contact sensitizer, if at all. However, particular exposures to PG-containing products might be associated with an elevated risk of sensitization. To identify such exposures, we analysed patch test data of 45 138 patients who have been tested with 20% PG in water between 1992 and 2002. Out of these, 1044 patients (2.3%) tested positively, 1083 showed a doubtful, follicular or erythematous reaction (2.4%) and 271 explicit irritant reactions (0.6%). This profile of patch test reactions is indicative of a slightly irritant preparation, and thus, many of the ‘weak positive’ reactions must probably be interpreted as false positive. No private or occupational exposures associated with an increased risk of PG sensitization were identified, except for lower leg dermatitis. Therefore, according to our patch test data, PG seems to exhibit very low sensitization potential, and the risk for sensitization to PG on uncompromised skin seems to be very low. [ABSTRACT FROM AUTHOR]

Enantiomers of 1,2-Propylene glycol (1,2-PG) were investigated in 64 commercial Chinese Baijiu including soy sauce aroma-type Baijiu (SSB), strong aroma-type Baijiu (STB), and light aroma-type Baijiu (LTB), via chiral gas chromatography ( β -cyclodextrin). The natural enantiomeric distribution and concentration of 1,2-PG in various baijiu were studied to evaluate whether the distribution and content of the two isomers of 1,2-PG were correlated with the aroma type and storage year. The results showed that 1,2-PG has a high enantiomeric ratio and the ( S )-configuration predominated in SSB. The average S / R enantiomeric ratio of this compound in SSB was approximately 87:13 (±3.17), with an average concentration of 52.77 (±23.70) mg/L for the ( S )-configuration and 8.72 (±3.63) mg/L for the ( R )-enantiomer. The ( R )-configuration was predominant in the STB, whereas neither ( S ) nor ( R )-form of 1,2-PG were detected in LTB. The content of the two configurations of 1,2-PG in the JSHSJ vintage of SSB showed a wave variation, with an average S / R enantiomeric ratio of 89:11 (±1.15). The concentration of ( R )-1,2-PG in XJCTJ vintage liquors showed an upward and then downward trend with aging time, with an overall downward trend, and the concentration of ( S )-form showed a wavy change with an overall upward trend. Except for the LZLJ-2019 vintage where both ( R ) and ( S )-1,2-PG were present, all other samples only existed ( R )-form, and a decreasing trend of ( R )-enantiomer with aging time was observed. The enantiomeric ratio of 1,2-PG might be one of the potential markers for adulteration control of Baijiu as industrial 1,2-PG usually presented in the racemic mixture. Sensory analysis revealed olfactory thresholds of 4.66 mg/L and 23.92 mg/L for the ( R )- and ( S )-configurations in pure water respectively. GC-O showed both enantiomers exhibited different aromatic nuances.

• Transformations of glucose to 1,2-propylene glycol. • Mechanical mixture of ZnO and Ru/C as catalysts in the presence of hydrogen. • The optimal temperature for glucose transformation to propylene glycol is 165 °C. • Thermodynamic analysis of possible reactions. • Kinetic modelling of a complex reaction network gave a reliable description of data. Transformations of glucose to 1,2-propylene glycol were studied over a mechanical mixture of ZnO and Ru/C catalysts in the presence of hydrogen. Different reaction conditions were evaluated by changing the reaction temperature and hydrogen pressure. In addition to the cascade mode of operation, also separate steps in the overall reaction network, such as hydrogenation of pyruvaldehyde and hydroxyacetone to 1,2-propylene glycol were investigated. Fructose as a starting material was also studied resulting in a propylene glycol yield of 37.5%. The optimal temperature for glucose transformation to propylene glycol was found to be 165 °C. The influence of temperature on the catalytic behavior was more prominent than the effect of hydrogen pressure. Thermodynamic analysis of glucose transformation to 1,2-propylene glycol was performed and a plausible kinetic model reflecting a complex reaction network was developed being able to describe the data in a reliable way. [ABSTRACT FROM AUTHOR]

A series of Pt nanoparticles supported on carbon nanotubes (CNTs) were synthesized using the incipient-wetness impregnation method. These catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM) techniques. The characterization results indicate that the Pt nanoparticles were highly dispersed on the surface of the CNTs, and the mean size was less than 5 nm. These catalysts were utilized to convert cellulose to hexitol, ethylene glycerol (EG), and 1,2-propylene glycol (1,2-PG) under low H2 pressure. The total yields were as high as 71.4% for EG and 1,2-PG using 1Pt/CNTs as the catalyst in the hydrolytic hydrogenation of cellulose under mild reaction conditions., (Copyright © 2014 Elsevier Ltd. All rights reserved.)