Bio-based Glycerol Research Articles

Ketalization mechanism of glycerol to biobased glycerol levulinate ketal over HZSM-5: A combined experimental and theoretical study

Methyl levulinate ketal (MLK) is a novel biobased chemical derived from glycerol via ketalization, and exploring its synthesis mechanism is of great significance for the high-value utilization of biomass resources. In this study, the ketalization reaction of glycerol was evaluated using the MLK yield calculated by the GC internal standard method. The acidity of HZSM-5 was determined by NH3-TPD. The catalyst screening experiments demonstrated that HZSM-5 in zeolites and AlCl3 in metal salts exhibited high catalytic activity in the synthesis of MLK. Furthermore, the kinetic results indicated that the HZSM-5 zeolite catalyst exhibited a lower apparent activation energy in catalyzing the synthesis of MLK compared to the metal salt catalyst AlCl3. The ketalization reactions of levulinate and glycerol catalyzed by different types of acidic sites in HZSM-5 were then investigated using the density functional theory method. A comprehensive catalytic path, free energy changes, intermediates, and transition state structures were proposed. Furthermore, the free energy barriers of ethyl levulinate ketal and butyl levulinate ketal catalyzed by HZSM-5 were calculated, and the difference between the steric hindrance effect and the electronic effect of alkyl in levulinate was compared. This study enhances the understanding of ketalization reactions and will be useful in future catalyst design studies.

SiO2-coated HZSM-5 catalysts for dehydration of bio-based glycerol to acrolein

As biodiesel production from triglyceride transesterification increases, by-product glycerol is accumulated, motivating the development of novel mechanism for converting glycerol into valuable chemicals. In the present work, for the selective production of acrolein from glycerol, SiO2-coated HZSM-5 molecular sieve with preciously controlled surface was designed. As characterized by NH3-TPD and pyridine adsorption IR, the total acid and the Lewis acid amounts of SiO2-coated HZSM-5 were decreased whereas the Brønsted acid amount remained almost unchanged. SiO2-coated HZSM-5 catalyst exhibited selectivity to acrolein of 64%, in glycerol conversion of 100% under reaction temperature of 300°C, much higher than HZSM-5 catalyst with acrolein selectivity of 52%. The catalytic activity durability was also improved by the modification of the surface properties because SiO2 coating reduced the surface acid amount and the micropore volume of HZSM-5, suppressing side reactions and inhibiting carbon deposition efficaciously.

Intensified Continuous Flow Process for the Scalable Production of Bio-Based Glycerol Carbonate.

A subtle combination of fundamental and applied organic chemistry toward process intensification is demonstrated for the large-scale production of bio-based glycerol carbonate under flow conditions. The direct carbonation of bio-based glycidol with CO2 is successfully carried out under intensified flow conditions, with Barton's base as a potent homogeneous organocatalyst. Process metrics for the CO2 coupling step (for the upstream production, output: 3.6 kg day-1 , Space Time Yield (STY): 2.7 kg h-1 L-1 , Environmental factor (E-factor): 4.7) outclass previous reports. High conversion and selectivity are achieved in less than 30 s of residence time at pilot scale with a stoichiometric amount of CO2 . Supporting DFT computations reveal the unique features of the mechanism in presence of Brønsted bases.

Reprocessable, chemically recyclable, and flame-retardant biobased epoxy vitrimers

Conventional epoxy thermosets exhibit outstanding mechanical performances, excellent thermal and dimensional stabilities, and prominent resistances to chemical/solvent corrosions but are limited because they are dependent on fossil resources, cannot be reprocessed, and are not fire safe. Herein, we reported biobased, flame-retardant, reprocessable, and chemically recyclable epoxy thermosets synthesized with bio-based glycerol triglycidyl ether (GTE) as an epoxy monomer, vanillin derived imine compound as a hardener, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a reactive fire-retardant agent. The curing kinetics investigation manifested that the curing reaction was activated with increasing DOPO content. The relationship between structure and properties of the vitrimers were studied in detail. The BEVs showed excellent physical properties with a tensile strength and glass transition temperature higher than 80 MPa and 100 °C, respectively. They possessed outstanding reprocessability and could be chemically recycled easily owning to the presence of the exchangeable imine bonds. The BEV with 6 wt% DOPO showed excellent fire resistance with a UL-94 V-0 rating and a LOI at 26.4% as well as much lower peak heat release rate and total heat release than the control vitrimer without DOPO. The BEVs with combination of excellent mechanical properties, reprocessability, chemical recyclability, and flame retardancy showed a bright future as an alternative to conventional epoxy thermosets for better sustainability and fire-safety.

Upgrading of Biobased Glycerol to Glycerol Carbonate as a Tool to Reduce the CO2 Emissions of the Biodiesel Fuel Life Cycle.

With regards to oil-based diesel fuel, the adoption of bio-derived diesel fuel was estimated to reduce CO2 emissions by approximately 75%, considering the whole life cycle. In this paper, we present a novel continuous-flow process able to transfer an equimolar amount of CO2 (through urea) to glycerol, producing glycerol carbonate. This represents a convenient tool, able to both improve the efficiency of the biodiesel production through the conversion of waste streams into added-value chemicals and to beneficially contribute to the whole carbon cycle. By means of a Design of Experiments approach, the influence of key operating variables on the product yield was studied and statistically modeled.

Development of a Novel Biobased Polyurethane Resin System for Structural Composites

Polyurethanes are gaining increasing interest for their use as structural components subjected to cyclic loads, such as leaf springs. Thermoset polyurethane (PUR) based technology offers some advantages, such as fatigue resistance, low viscosity, and fast curing. However, current PUR formulations present two major drawbacks: their petrochemical origin and high reactivity. The aim of this work was to develop a novel biobased PUR (BIO-PUR) with the required mechanical properties and processability for manufacturing structural composites by resin transfer moulding (RTM). For this purpose, a high functionality and high hydroxyl index castor-oil-based polyol was used combined with a biobased glycerol (BIO-Gly) to increase the crosslinking density and improve the final properties of the BIO-PUR. The viscosity and reactivity of the different systems were studied by means of rheology tests and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied by dynamic mechanical analysis (DMA) and flexural tests. Furthermore, the RTM process of a representative part was simulated and validated through the manufacturing and testing of plates. The properties of the BIO-PUR resin systems were strongly influenced by the addition of biobased glycerol and its effect on the crosslinking density. The combination of a high functionality and hydroxyl index biobased polyol with the biobased glycerol resulted in a high-performance BIO-PUR with the required reactivity and final properties for structural applications.

Synthesis of a Multiperiod C–H–O Symbiosis Network for the Potential Valorization of Glycerol to PHA Production

The synthesis of the carbon–hydrogen–oxygen symbiosis network (CHOSYN) provides a structured framework for dealing with multiscale integration of hydrocarbon processing industries to improve resource efficiency and reduce waste generation. However, the earlier CHOSYN design approaches presumed that the networks operate in a single mode throughout the year. This may not be the case in real-world situations where the production of certain plants such as polyhydroxyalkanoates (PHAs) from bio-based glycerol may require multiple operational modes to accommodate the seasonal variability and availability of raw material. PHAs are biodegradable polymers produced by bacterial fermentation of carbon sources, which are the potential substitutions for petrochemical-based plastics. Hence, this work aims to propose a systematic approach to optimize multiperiod mass integration in the development of a CHOSYN. The central principle of the proposed approach is the incorporation of a storage and dispatch system into the conventional CHOSYN design for the supply of chemical species needed in the network throughout different operational periods. A case study considering glycerol valorization and other chemical plants using the devised CHOSYN model was conducted to evaluate the performance of the proposed design against the conventional CHOSYN in terms of sustainability metrics. The results demonstrate the advantages of the CHOSYN model with a storage and dispatch system by exhibiting a better profitability outcome than the conventional multiperiod CHOSYN through operating cost savings.

Glycerol valorization: Development of selective protocols for acetals production through tailor-made macroreticular acid resins

Bio-based glycerol and aldehydes have been valorized by acetalization reaction over novel macroporous sulfonated polystyrene-type resins (MR-SP20-SO3H and MR-SP50-SO3H). The influence of reactants molar ratio, catalyst amount, temperature, and reaction time on the activity and selectivity to acetals have been investigated. Results showed that MR-SP20-SO3H and MR-SP50-SO3H confirm a high performance in the acetalization of the glycerol derivatives 1,2- propandiol, 1,3-propandiol, 3-methoxy-1,2-propandiol and monoacetin; these catalytic systems enable recover and reuse.

Anaerobic co-digestion of sewage sludge and bio-based glycerol: Optimisation of process variables using one-factor-at-a-time (OFAT) and Box-Behnken Design (BBD) techniques

The use of glycerol as a co-substrate in anaerobic processes is a promising method of reducing the amounts of contaminants in sewage sludge. Although anaerobic co-digestion has been in existence for more than a century, its operating conditions have not yet been fully optimised. This paper focuses on the optimisation of anaerobic variables so as to optimise biogas yield using both the one-factor-at-a-time (OFAT) method and the Box-Behnken Design (BBD) method. The experimental work was carried out using batch digesters that were operated between 25 and 50∘C, 0.5 and 1.5 g VSfed / (g VSinoculum), and 1 and 9 g glycerol / L for the optimisation of temperature, substrate to inoculum ratio (S:I) and glycerol concentration, respectively. Sewage sludge was used as a primary substrate, bio-based glycerol was used as the secondary substrate (co-substrate) and the digestate from a local wastewater treatment system was utilised as an inoculum. In both the OFAT method and the BBD method, the highest biogas yield of 0.94 L / (g VSfed) was attained at a temperature of 50∘C, S:I ratio of 1 g VSfed / (g VSinoculum) and glycerol concentration of 1 g glycerol / L. Biogas yield decreased below 50∘C, and the process experienced overloading above 1 g VSfed / (g VSinoculum) and 1 g glycerol / L. Using the BBD method, the effect of variables, which measures a change in response over a change in variable, showed that glycerol concentration had the greatest impact on the biogas yield, then temperature, and lastly S:I ratio. The model with the best fit was a quadratic model with a standard deviation of 0.09, coefficient of variation of 18.54%, and PRESS of 0.66. In conclusion, optimisation of anaerobic process variables to optimise biogas yield was successfully carried out using the OFAT method and the BBD method.

Efficient Synthesis of Biobased Glycerol Levulinate Ketal and Its Application for Rigid Polyurethane Foam Production

Glycerol levulinate ketal (GLK) is a novel biobased chemical compound with great potential for industrial applications, especially in the areas of green solvents and polymeric materials. For the fi...

A Novel Strategy for Selective O-Methylation of Glycerol in Subcritical Methanol.

A new regioselective approach has been elaborated for the selective conversion of bio-based glycerol into the monomethyl derivative using sub/supercritical methanol. The reaction was realized in a batch process using three reactive components, namely, glycerol, methanol, and potassium carbonate to selectively produce the 3-methoxypropan-1,2-diol in mild yields; the mechanism of the O-methylation has been delineated using labeled methanol and GC-MS experiments.

Continuous flow upgrading of glycerol toward oxiranes and active pharmaceutical ingredients thereof

A robust continuous flow procedure for the transformation of bio-based glycerol into high value-added β-amino alcohol active pharmaceutical ingredients.

Synthesis and characterization of castor oil-based branched polyols from renewable resources and their polyurethane-urea coatings

The chemical modifications of castor oil (CO) to develop branched polyols and their polyurethane-urea coatings have been investigated. For this purpose, castor oil-based branched polyols (COBPs) were synthesized from CO by modifying with succinic anhydride followed by reaction with hydroxyl group moieties like petrochemical-based pentaerythritol, trimethylolpropane and bio-based glycerol. The COBPs were characterized by using Fourier transform infrared, 1H and 13C nuclear magnetic resonance spectroscopies, gel permeation chromatography and differential scanning calorimetry. These COBPs were further urethanized with isophorone diisocyanate at OH/NCO ratio of 1:1.6 to get the isocyanate-terminated polyurethane prepolymers. The surplus isocyanate groups of the prepolymer were cured with atmospheric moisture at ambient temperature condition to form uniform film with fast surface drying. The thermo-mechanical, viscoelastic and swelling properties were evaluated for the cured coating films. Properties have been discussed from the viewpoint of branched network and also the urethane segment present in the structure. The glass transition temperatures of the coating films were found to be in the range of 32–64°C. The modified castor oil coating films show better thermo-mechanical and viscoelastic properties in comparison with control (unmodified castor oil) coating films. This work delivers an effective and promising way to synthesize branched moieties in plant oil-based high performance coatings.

Poly(glycerol-co-diacids) Polyesters: From Glycerol Biorefinery to Sustainable Engineering Applications, A Review

Upgrading of biobased glycerol to commercial products is a necessary step on sustainable development of oleaginous biomass biorefining. The synthesis of poly(glycerol-co-diacid) polyester materials is an attractive option for glycerol usage that can produce a wide range of products of commercial interest. These polymeric materials could be used on industrial applications as biomedical devices, surfactants and in thermoplastic material development. In this review, the process engineering aspects leading to tailorable polymeric products are comprehensively analyzed with emphasis on control of molecular architecture and functionality. Molecular weight, degree of branching, mechanical properties and surface chemistry of the materials can be controlled by fine-tuning synthesis procedures to match custom specifications in end products. Potential usage of poly(glycerol-co-diacid) materials with tailored physicochemical properties on industrially relevant applications is presented. Advantages and challenges in th...

Improvement of Impact Toughness of Biodegradable Poly(butylene succinate) by Melt Blending with Sustainable Biobased Glycerol Elastomers

Poly(butylene succinate) (PBS) was melt blended with glycerol based polyesters (PGS) synthesized from pure and technical glycerol aiming to improve the impact strength of PBS. It was found that after addition of 30 wt% PGS to PBS its impact strength was significantly increased by 344% (from 31.9 to 110 J/m) and its elongation at break was maintained at 220%. Infrared spectra of the blends showed the presence of hydroxyl groups from the PGS phase suggesting that hydrogen bonding between the phases could be responsible for a good stress transfer and an efficient toughening in the PBS/PGS blends. Scanning electron microscopy imaging showed a good dispersion of PGS phase into PBS with a PGS particle size of 10 μm and less and no agglomeration. Addition of PGS to PBS was shown to be an effective strategy for improvement of PBS impact resistance without serious detrimental effects on its thermal and rheological properties.

ChemInform Abstract: Phosphine Ligand‐Free RuCl3‐Catalyzed Reductive N‐Alkylation of Aryl Nitro Compounds.

Without using any additional ligands, RuCl3 efficiently catalyses the reductive N-alkylation of aryl nitro compounds with alcohols using bio-based glycerol as the hydrogen source and without the need for any added solvents. The reaction can be easily manipulated to produce either imines or secondary amines in high yields. RuCl3-catalyzed reductive N-alkylation of nitroarenes with alcohols affords the corresponding imine products in good to excellent yields. Under the same reaction conditions, the one-pot sequential reaction of nitroarenes with alcohols and glycerol also gives amines in higher yields.

Phosphine ligand-free RuCl3-catalyzed reductive N-alkylation of aryl nitro compounds

Without using any additional ligands, RuCl3 efficiently catalyses the reductive N-alkylation of aryl nitro compounds with alcohols using bio-based glycerol as the hydrogen source and without the need for any added solvents. The reaction can be easily manipulated to produce either imines or secondary amines in high yields. RuCl3-catalyzed reductive N-alkylation of nitroarenes with alcohols affords the corresponding imine products in good to excellent yields. Under the same reaction conditions, the one-pot sequential reaction of nitroarenes with alcohols and glycerol also gives amines in higher yields.

Free-solvent Michael addition of glycerol to acrylic compounds

Functionalization of biobased glycerol by acrylic compounds was optimized and the tricyanoethylglycerol can be used as a prochiral core of dendrimers.

Au/Ag–Mo nano-rods catalyzed reductive coupling of nitrobenzenes and alcohols using glycerol as the hydrogen source

A highly efficient Au/Ag-Mo nano-rods catalyst was prepared for the one-pot synthesis of imine and amine using equal molar ratio of nitrobenzene and alcohol as starting materials, and bio-based glycerol as the hydrogen source. The reaction mechanism of the nitrobenzene reduction, amine and aldehyde coupling, and imine reduction was explored.

Incorporating environmental impact assessment into conceptual process design: A case study example

The purpose of this contribution is to present a case study illustrating how environmental impact assessment using the U.S. EPA Waste Reduction Algorithm has been incorporated into conceptual process design. This will be achieved via the introduction of a simple methodology for integrating environmental impact assessment into the standard heuristics of conceptual process design to ensure that environmental and sustainability goals are met while maintaining economic viability. The case study presented to illustrate the methodology is based on a process to manufacture industrially important C3 compounds from the dehydration of bio-based glycerol. The selected case study is important from the perspective of sustainability because glycerol is produced as a byproduct of the manufacture of biodiesel from vegetable oils. © 2008 American Institute of Chemical Engineers Environ Prog, 2009