Polyol Yield Research Articles

Optimization of reed-based polyol production driven by response surface methodology and machine learning: Process modeling and hydroxyl value prediction

In pursuit of sustainable development goals, the transformation of biomass resources into high-value chemicals has become a focal point within the academic community. Despite being a biomass resource, reed (Phragmites australis) has not yet fully realized its potential in the production of bio-based polyols. This study utilized Response Surface Methodology (RSM) and an Artificial Neural Network (ANN) enhanced by a Genetic Algorithm (GA) to model and optimize the liquefaction process of reeds. Furthermore, this study employed a pre-existing predictive model to estimate the hydroxyl value of reed-derived liquefaction products, thereby aiming to curtail expenses during the biomass chemical development phase. The results demonstrated that both the RSM and GA-ANN models accurately predict bio-polyol yield, with the RSM model outperforming the ANN model. Based on optimal conditions predicted by the RSM model, the best experimental process parameters were established: raw material particle size 2–12 mesh, solid-liquid ratio 5:1, glycerol content 32.5 %, catalyst content 3.6 %, temperature 169 °C, and reaction time 58 minutes. Under these conditions, the polyol yield reached 89.145 %, with a relative deviation of 2.366 %, and the bio-polyol exhibited a viscosity of 0.51 Pa·s. The predicted hydroxyl value for the bio-based polyol was found to be 399.19 mg KOH/g. The liquefied product is rich in hydroxyl groups, indicating its potential application value in preparing bio-based polymer materials. This study introduces innovative approaches to the economical production of bio-based polyols at the laboratory scale, which may pave the way for their broader industrial implementation.

Significant promotion of MgOy in bifunctional Pt-WOx-MgOy catalysts for the chemoselective conversion of glucose to lower polyols

A novel catalyst prepared by a facile ‘one-pot’ solvothermal method was developed for the efficient production of lower polyols from glucose solution. Under the optimal reaction conditions, the yield of diols was up to 50.7%, outperforming the recent works reported in the literature (<48%). Deeper investigation results revealed that the modification of MgOy on Pt-WOx could tune the surface acid-base properties, thereby promoting the yield of lower polyols. Combining the experimental and characterization results, a possible reaction mechanism during the conversion of glucose to lower polyols over Pt-WOx-MgOy was proposed.

Effect of different catalysts on the oxyalkylation of eucalyptus Lignoboost® kraft lignin

Abstract Lignin obtained by Lignoboost® procedure from black liquor after kraft pulping of Eucalyptus globulus wood was characterized and converted into liquid polyols via an innovative and safe procedure using base catalyzed oxyalkylation with propylene carbonate (PC). The effect of four catalysts, Potassium carbonate (K2CO3), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU), dicyanodiamide (DICY), and 1,4-diazabicyclo [2.2.2] octane (DABCO) was evaluated in terms of lignin polyol yield and weight gain. The ensuing polyols were also characterized by fourier transform infrared (FTIR), 1H NMR, 13C NMR, and size exclusion chromatography (SEC) to determine the degree of the substitution (DS), degree of polymerization (DP), and the molecular weight, respectively. Only a minor proportion of PC (ca. 3–15%) was converted to propylene glycol/homooligomers as revealed by high performance liquid chromatography (HPLC). All catalysts promoted preferential derivatization of lignin phenolic OH groups by oxypropyl moieties. The maximum average DP of propylene oxide chains in oxyalkylated Lignoboost® kraft lignin (oKL) was 1.85 per one phenylpropane unit (PPU) using DBU. Conversely, the DP of oKL using DICY was very low (0.27/PPU). DICY’s catalytic activity seems to be jeopardized due to the formation of unreactive adducts with lignin. The oKL obtained using DBU, DABCO, and K2CO3 have potential to be used as polyols in the production of polyurethanes as the corresponding hydroxyl number (IOH) is in the range of 198–410 mg KOH g−1.

Effects of some material parameters on lignin biopolymer liquefaction by microwave heating

A kraft lignin was liquefied in solution reagents such as polyethylene glycol (PEG) and glycerol under microwave heating. The effects of glycerol concentration, molecular weight of PEG and lignin mass were investigated on lignin liquefaction process through microwave irradiation. For this purpose, the prepared polyols were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and carbon-13 nuclear magnetic resonance techniques. Further, the hydroxyl value (OHV) of polyols was determined by titration method. The results indicated that addition of glycerol increased liquefaction yield and OHV of polyols due to its role as co-solvent in liquefaction process and as a microwave absorber. Glycerol could be used up to 30 wt%, though the beneficial amount of glycerol was obtained as 20 wt%. In another run, it was observed that PEG with a molecular weight of 400 g/mol was an efficient solvent in liquefaction process, which introduced the highest amount of OHV in lignin polyol. A study on the effect of lignin mass was carried out with sufficient amount of glycerol and PEG400 as liquefaction reagents. The results revealed that with further increase in lignin/solvent weight ratio, the molecular weight of polyol increased while its OHV was reduced. Therefore, there was a limiting range in addition of lignin due to insufficient liquefaction solvent in causing enhanced condensation reaction during the liquefaction process. Finally, the polyol with sufficient amounts of testing components was nominated as an optimal polyol with the highest OHV (630 mg KOH/g) and suitable liquefaction yield.

Nickel–Tungsten Supported on Thin Carbon Coated SiO2 Nanosphere for Cellulose Conversion to Lower Polyols

Production of polyols and other chemicals from cellulose was important for sustainable society, and it had long relied on the design of suitable catalysts to achieve high yield of lower polyols. Herein, we reported a new preparing strategy for nickel–tungsten catalyst to fabricate Ni–W/SiO2@C catalysts coated by thin carbon. The crystal carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2. The prepared composites were characterized by means of XRD, N2 physisorption, thermogravimetry, XPS, TEM, element mapping and atomic force microscope. These characterizations confirmed that more phases including WO3, Ni, NiW alloys and NiC were formed by incorporation of porous crystal carbon. Moreover, the metallic particles were dispersed in size range of 2–8 nm influenced by coating carbon and ethanediamine (dispersant). The activities of catalysts were evaluated in hydrogenolysis of cellulose to lower polyols at 240 °C under 5.0 MPa H2 pressure in the presence of water. Results showed that catalyst Ni–W/SiO2@C-12 was more favorable for EG production, with the highest EG yield of 60.7% and 100% cellulose conversion after reaction for 60 min. The series of high efficient nickel–tungsten catalysts Ni–W/SiO2@C were fabricated and coated by thin carbon. The thin coating carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2.

Mn-promoted hydrogenation of microalgae (Chlorococcum sp.) to 1,2-propanediol and ethylene glycol over Ni-ZnO catalysts

Mn-promoted nickel-based catalysts were explored for the direct hydrogenation of microalgae (Chlorococcum sp.) containing 49.6% of carbohydrates in water. With this catalyst at 250 °C for 3.0 h, microalgae was completely decomposed, where the conversion of microalgae to liquid products (CTL) and the total yield of polyols reached 66.9%, and 53.6%, respectively. Among polyols, the total yield of 1,2-propanediol and ethylene glycol were 41.7%. XRD, XPS and TEM-EDX characterizations showed that 5% of Mn addition, 350 °C of reduction temperature and the co-precipitation synthesis ensured the excellent dispersion of the Ni catalyst with small particle sizes. The Mn promoter was found to stabilize the catalyst structure by preventing the Ni particles from aggregation and to effectively promote retro-aldol and dehydroxylation reaction due to the increasing number of Lewis acid sites. Meanwhile, the hydrogenation pathways over nickel-based catalysts were proposed.

Life Cycle Assessment of Polyol Fuel from Corn Stover via Fast Pyrolysis and Upgrading

The purpose of this study is to evaluate the fossil energy consumption and the greenhouse gas (GHG) emissions of polyol fuel produced via corn stover fast pyrolysis and bio-oil upgrading based on life cycle assessment (LCA). The required material and energy inputs involved in the unit processes of LCA are taken from Aspen Plus simulation models established according to a demonstration plant with annual polyol output of 1000 tonnes. The eBalance software with a Chinese Life Cycle Database (CLCD) is employed to perform this task. The research results show the net fossil energy input (FEI) and the net global warming potential (GWP) of polyol fuel are respectively 0.760 MJ and 0.0444 kgCO2,eq per MJ energy output under the proposed production pathway. Compared to petroleum-based gasoline and diesel, the net FEI of polyol fuel reduces by 42.9% and 42.2% respectively and the net GWP of polyol fuel decreases by 55.1% and 56.9% accordingly. Sensitivity analysis indicates the data uncertainty of the polyol yield a...

The Synthesis of Bio-Polyol from Epoxidized Soybean Oil

Abstract: Hydroxyl and oxirane functionality were calculated from molecular weight and hydroxyl or oxirane-oxygen content of polyol. The effect of reaction parameters like the amount of reagents, catalyst, temperature and time on a polyol synthesis was studied through the hydroxyl and oxirane functionality of product. Moreover, the impact of the parameters on the selectivity of catalyst was determined by comparing a polyol yield to an epoxide ring opening yield. When the hydroxylation reaction was carried out with ESO:H2O molar ratio of 1:15; in 8 wt.% of H2SO4; at temperature of 70oC and in 5 hours, the polyol yield of reaction was 70.32% and the hydroxyl functionality of polyol reached to 5.63

One-pot selective conversion of cellulose into low carbon polyols on nano-Sn based catalysts

The direct hydrogenolysis of cellulose on bimetallic catalysts represented a promising route for polyols' production. The development of a catalyst system that could control the promotion of the selectivity of polyols for the conversion cellulose into polyols was highly desirable. In this work, we realized the production of ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG) by adopting nano-Sn species with different valences in combination with Ni catalysts, and the catalysts were prepared by the incipient-wetness impregnation method. The catalyst 10%Ni–15%Sn/SBA-15 achieved the highest yield of C2-C3 polyols, yielding up to 67.2% with a higher selectivity to 1,2-PG. The Ni and Sn species and some NiSn alloys were found to be the active sites for the EG and PG as evidenced by control experiments and characterization including X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The catalytic particles were located on the outer surface of SBA-15 (pore size = 6–10 nm) on a nanoscale with sizes of 11.1 ± 1.9 nm. The effects of the supports and hydrogenating species were investigated for cellulose conversion. The experimental results disclosed that the Sn species with different valences possessed obvious functions for the retro-aldol condensation, and the Ni components boomed the hydrogenation process. The other detailed analyses on the formation of polyols were described. As a consequence, controlling the EG and PG product distribution could be realized using Sn based catalysts.

Selectivity-Switchable Conversion of Cellulose to Glycols over Ni–Sn Catalysts

The direct hydrogenolysis of cellulose represents an attractive and promising route for green polyol production. Designing a catalyst system that could control the selectivity of polyols of this process is highly desirable. In this work, we realized the selectivity-switchable production of ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG) by using Sn species with different valences in combination with Ni catalysts. The combination of Ni/AC and metallic Sn powders exhibited a superior activity toward EG (57.6%) with up to 86.6% total polyol yield, while the combination of Ni/AC and SnO favored the formation of 1,2-PG (32.2%) with a 22.9% yield of EG. The Sn species in NiSn alloy in situ formed from metallic Ni and Sn powders was found to be the active sites for the high selectivity of EG as evidenced by control experiments and characterizations including X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, energy dispersive X-ray mapping, and 119Sn Mos...

Efficient Hydrolytic Hydrogenation of Cellulose on Mesoporous HZSM-5 Supported Ru Catalysts

Hydrolytic hydrogenation of cellulose requires both functionalities of a metal and acid site. HZSM-5 has strong acid sites inside the micropores. However, those sites are not easily accessible to large molecules derived from cellulose. In this work, NaOH treatment of ZSM-5 was applied to introduce mesopores to the crystallite of ZSM-5. Characterizations showed that mesopores of 4–20 nm were successfully created on the surface of ZSM-5, and mesopore volume and total acid density (particularly Lewis acid density) increased as the severity of treatment increased. Loading of Ru on the mesoporous HZSM-5 resulted in a highly active and selective catalyst for conversion of cellulose to hexitols. The optimized hexitols yield of 39.4 % is 6 times higher than that of Ru supported on the parent HZSM-5. Model reaction studies (hydrolysis of cellobiose and hydrogenation of glucose) indicated that the enhanced acid density (particularly Lewis acid in mesopores) promotes the hydrolysis of oligosaccharides from primary depolymerization of cellulose. Furthermore, the uniform dispersion of smaller Ru nanoparticles due to the increased surface area caused by the mesopore enhanced the activity of the hydrogenation reaction. Consequently, a high yield of hexitols with reduced yield of small polyols was achieved on the optimized mesoporous Ru/HZSM-5.

Process development of short-chain polyols synthesis from corn stover by combination of enzymatic hydrolysis and catalytic hydrogenolysis

Currently short-chain polyols such as ethanediol, propanediol, and butanediol are produced either from the petroleum feedstock or from the starch-based food crop feedstock. In this study, a combinational process of enzymatic hydrolysis with catalytic hydrogenolysis for short-chain polyols production using corn stover as feedstock was developed. The enzymatic hydrolysis of the pretreated corn stover was optimized to produce stover sugars at the minimum cost. Then the stover sugars were purified and hydrogenolyzed into polyols products catalyzed by Raney nickel catalyst. The results show that the yield of short-chain polyols from the stover sugars was comparable to that of the corn-based glucose. The present study provided an important prototype for polyols production from lignocellulose to replace the petroleum- or corn-based polyols for future industrial applications.

Hydrogenolysis of cellulose to valuable chemicals over activated carbon supported mono- and bimetallic nickel/tungsten catalysts

The hydrogenolysis of cellulose was systematically investigated at 488 K and under 65 bar H2 in the absence of a catalyst and over six different catalytic systems containing nickel and/or tungsten on activated carbon (AC) in order to understand the role of individual active components (AC, W/AC, Ni/AC, a physical mixture of Ni/AC + W/AC, and two differently prepared Ni/W/AC catalysts) with respect to the product distribution wherein polyols (e.g. ethylene glycol (EG), propylene glycol, and sorbitol) are highly valuable chemicals. Without a catalyst and when using only AC, a hydrochar, due to hydrothermal carbonization of cellulose, was obtained. Although the catalyst W/AC was effective for the degradation of cellulose (high conversion of 90%) and facilitates C–C bond cleavage, selective production of any product was not possible, and the carbon efficiency (CEL) is the lowest (9.1%). Also, with highly dispersed Ni on AC the polyol yield was only 5.3%. The desired behavior showed Ni/W/AC provided its preparation occurs by a two-step incipient wetness (IW) technique. Starting with a remarkably high cellulose/catalyst ratio of 10, a cellulose conversion of 88.4%, CEL of 78.4% and EG yield of 43.7% were achieved (overall polyol yield = 62.1%). Drastically lower yields towards EG by an order of magnitude and decreased CEL were obtained by a co-impregnated Ni/W/AC catalyst and the Ni/AC + W/AC mixture. By the detailed analysis via XRD, TPR and CO chemisorption, it can be concluded that in the Ni/W/AC catalyst, after the first IW step of the activated carbon with ammonium metatungstate hydrate and the following reduction in H2 up to 1128 K, metallic tungsten was formed. This leads, in combination with the hydrogenation properties of nickel introduced in the second IW step, to a virgin bimetallic catalyst, i.e. before the hydrogenolysis starts, in which both components must be metallic. This is a prerequisite for high polyol production. Finally, varying the AC type, high space–time-yields up to 2.5 g polyols (gcatalyst h)−1 were obtained. A slight deactivation after two runs followed by a strong decrease of polyol yield in the next two runs was observed. Leaching and structural changes on the catalyst surface (formation of NiWO4) are mainly responsible for deactivation.

Novel Renewable Polyols Based on Limonene for Rigid Polyurethane Foams

Novel renewable polyols based on limonene were synthesized using thiol-ene “click” chemistry. These limonene based polyols were structurally characterized using wet methods (hydroxyl number, acid value and viscosity), gel permeation chromatography and spectroscopic methods. The results indicated that high yield of polyols from limonene based materials can be obtained using thiol-ene reaction. These limonene based polyols were used successfully for preparation of rigid polyurethane foams. These foams had regular shape cells and uniform cell size distribution. Thermal studies on these foams indicated that foams were thermally stable up to 250 °C. The glass transition temperature of the foams was higher than 200 °C. These rigid polyurethane foams had high compressive strength and the highest compressive strength of 195 kPa was observed. These foams have good physical–mechanical characteristics and could be suitable for all the applications of rigid polyurethane foams such as thermal insulation of freezers, storage tanks for the chemical and food industries, and packing materials for food industries.

제올라이트에 담지된 백금 촉매를 이용한 셀룰로우스의 폴리올로의 직접 전환

The direct conversion of cellulose into polyols in was examined over Pt catalysts supported on various zeolites, viz., mordenite, Y, ferrierite, and . For comparison, Pt catalysts supported on , , and were also tested. The physical properties of the catalysts were probed with physisorption. The surface acidity was measured with temperature programmed desorption of ammonia (-TPD). The Pt content was quantified with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The Pt dispersion was determined with CO chemisorptions and transmission electron microscopy (TEM). The conversion of cellulose appeared to be mainly dependent on the reaction temperature and reaction time because it depends on the concentration of ions reversibly formed in hot water. Pt/H-mordenite (20) showed the highest yield to polyols among the tested catalysts. Pt/H-zeolite was superior to Pt/Na-zeolite for this reaction. The polyol yield was dependent on the surface acid density and the external surface area.

Direct conversion of cellulose into polyols over Ni/W/SiO2-Al2O3

The direct conversion of cellulose into polyols over Ni/W/SiO2-Al2O3 catalysts with different Al molar fractions was examined. For comparison, Cu/W/SiO2-Al2O3, Fe/W/SiO2-Al2O3, and Co/W/SiO2-Al2O3 were also evaluated. The bulk crystalline structure was determined using X-ray diffraction (XRD). The surface acidity was probed via temperature-programmed desorption of ammonia (NH3-TPD). The textural properties were investigated using N2 physisorption. The metal contents were confirmed via inductively coupled plasma–atomic emission spectroscopy (ICP-AES). Among the various metal catalysts, Ni/W/SiO2-Al2O3 was confirmed to be the most favorable for hydrogenolysis of cellulose into polyols. The effect of the Al molar fraction in SiO2-Al2O3 on this reaction over Ni/W/SiO2-Al2O3 was also investigated. It was found that the polyol yield was closely related to the total acidity of the support. Compared to Ni/W/SBA-15, Ni/W/SiO2-Al2O3 (Al/(Al+Si)=0.6) showed better stability during the recycling test. The catalyst deactivation was confirmed to be caused by metal leaching.

Production of new soy-based polyols by enzyme hydrolysis of bodied soybean oil

Polyols are one of the predominate reactants in polyurethane synthesis. Soy-based polyols are potentially low-cost materials in plastic and polymer industrials for decades. However, the performance of most commercial soy-based polyols is limited by their low molecular weights (low hydroxy equivalent weights), low alcohol reactivity due to the prominence of secondary moieties, and limited control on crystalline behavior due to large non-functional branches on the soy-based polyols. The objective of this investigation was to produce new soy-based polyols from enzyme hydrolysis. Soy-based polyols were synthesized by a two-step process consisting of heat bodying soybean oil followed by enzyme hydrolysis of bodied soybean oil. Possible advantages of this approach include the production of primary alcohol moieties, reduction of saturated fatty acid moieties, control of hydroxy equivalent weights, and elimination of organic co-reagents. Several commercial enzymes were investigated for removing saturated fatty acids and imparting the hydroxy functional groups in order to produce the better soy-based polyols. The lipase from Candida rugosa significantly hydrolyzed palmitic acid and was recommended to be used to produce the soy-based polyols. Burkholderia cepacia, Aspergillus niger, Mucor javanicus, and Rhizomucor miehei lipases showed some significance in the hydrolysis against palmitic acid and against stearic acid for some reaction conditions. The soy-based polyols were produced with a hydroxy number of about 50 mg KOH/g after only 3 h of the simple hydrolysis reaction by lipase C. rugosa. Higher hydroxy numbers could be obtained with the longer reaction time. However, polyol yield was reduced and undesirable acid residue was increased when the percent hydrolysis increased.

Engineering aspects of the production of sugar alcohols with the osmophilic yeast Moniliella tomentosa var pollinis: Part 2. Batch and fed-batch operation in bubble column and airlift tower loop if reactors

Moniliella tomentosa var pollinis was cultivated on complex medium consisting of glucose as carbon source, urea, (NH 4) 2SO 4, corn steep liquor and yeast extract as nitrogen sources, respectively. The pH and the concentrations of (dry) cell mass, glucose, erythritol, ribitol, glycerol, disaccharides, trisaccharides, polysaccharides, amino acids in medium, oxygen and carbon dioxide in off-gas were monitored during the cultivation. Rates of growth, substrate uptake and production, yields and yield coefficients as well as OUR, CO 2 production rate and respiratory coefficient were evaluated with different medium composition and operating conditions with two mutants in 80 l bubble column and 80 l airlift tower loop reactors in batch and fed-batch operation. Foam height, gas hold up, bubble velocity, and specific gas/liquid interfacial area were measured in situ. The proteins in medium were investigated with SDS-PAGE. At high concentrations (up to 500 g l −1) high (dry) cell mass concentrations (up to 65 g l −1), high erythritol concentrations (up to 175 g l −1) erythritol yield (43%) and yield coefficients (0.58 g g −1) as well as polyol concentrations (250 g l −1) polyol yield (60%) and yield coefficients (0.70 g g −1) were obtained under optimal conditions. With a mutant somewhat better results were obtained. Under oxygen limitation ethanol was formed, and under nitrogen limitation strong foam formation impaired the production process. By suitable aeration and fed-batch process using mixture of glucose and nitrogen source for feeding, ethanol and foam formation could be reduced and eliminated, respectively. The strong effect of antifoam agent in the medium on the fluid dynamic of the two-phase system and the dissolved oxygen concentration was demonstrated.

Engineering aspects of the production of sugar alcohols with the osmophilic yeast Moniliellatomentosa var pollinis. Part I. Batch and fed-batch operation in stirred tank

Moniliella tomentosa var pollinis was cultivated on complex medium consisting of glucose as carbon source, urea, (NH 4) 2SO 4, corn steep liquor and yeast extract as nitrogen sources, respectively. The pH and the concentrations of (dry) cell mass, glucose, erythritol, ribitol, glycerol, disaccharides, trisaccharides, polysaccharides, amino acids in medium, oxygen and carbon dioxide in off-gas were monitored during cultivation. Rates of growth, substrate uptake and production, yields and yield coefficients as well as OUR, CPR and RQ were evaluated with different medium composition and operating conditions in a 30 l stirred tank by batch and fed-batch operation. At high substrate concentrations in batch operation high (dry) cell mass concentrations (65 g l −1), high erythritol concentrations (90 g l −1) erythritol yield (36%) and yield coefficients (0.35 g g −1) as well as polyol concentrations (150 g l −1) polyol yield (62%) and yield coefficients (0.65 g g −1) were obtained under optimal conditions. With fed-batch operation better results were obtained: high (dry) cell mass concentrations (up to 116 g l −1), high erythritol concentrations (up to 170 g l −1), polyol concentrations (up to 188 g l −1) were obtained under optimal conditions. Under oxygen limitation ethanol was formed, and under nitrogen limitation foam formation impaired the production process. By suitable aeration and a fed-batch process using a mixture of glucose and nitrogen source for feeding, ethanol and foam formation could be reduced and eliminated, respectively.