Yield Of Isosorbide Research Articles

Optimizing sorbitol double dehydration: A Box-Behnken design approach with commercial sulfonic acid resin

In this study, double dehydration of sorbitol into isosorbide using commercial sulfonic acid resin as a catalyst was carried out under vacuum conditions generated by water ejection. To improve the efficiency and selectivity of the process, optimum reaction conditions prescribed by temperature, catalyst loading, and reaction time were investigated using the Box-Behnken design (BBD) together with Response Surface Methodology (RSM). The results showed that using the water ejection system could increase reaction activity. Statistically, all the reaction parameters were found to significantly affect the double dehydration reaction response, including sorbitol conversion, 1,4-sorbitant yield, and isosorbide yield. Furthermore, accurate predictive equations for all the reaction responses displayed R2 > 95 %, with no significant errors observed. The optimized conditions resulted in the complete conversion of sorbitol with 6.42 % 1,4-sorbitant yield and 67.55 % isosorbide yield. The equations yielded predicted values of the responses with minor variances being lower than 1 % when compared with the experimental values. However, the efficiency of the catalyst decreased steadily over recycling cycle due to reduced active sites and textural properties, likely caused by structural collapse and by-product accumulation. This work contributes to biomass valorization by optimizing the effective process for the production of isosorbide via commercial catalysts under vacuum conditions.

Experiments and kinetic modeling of the sorbitol dehydration to isosorbide catalyzed by sulfuric acid under conditions of non-constant volume

Isosorbide is a novel bio-based material, derived as a secondary dehydration product of sorbitol. This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of non-constant volume. Herein, the effects of stirring rate, catalyst dosage, reaction temperature, and reaction time on the dehydration reaction of sorbitol were investigated. The yield of isosorbide up to 77.13% was obtained after 1.5 hours of reaction time under conditions of 2 kPa, 1.0% (mass) catalyst dosage, and 413.15 K. Based on the sorbitol dehydration reaction mechanism and a simplified reaction network, a kinetic model was developed in this work. A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K. The fitting results indicate that side reactions with higher activation energy are more affected by reaction temperatures, and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol. The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect. Hopefully, the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.

Dense Ru single-atoms integrated with sulfoacids for cellulose valorization to isosorbide

Metal-acid bifunctional catalysts are the unity of two opposites (metal-acid repelling) for cellulosic biomass valorization to isosorbide. It is challenging to improve the selectivity of metal hydrogenation catalysts and their synergism with acids for catalytic hydrolysis and dehydration to achieve substantial isosorbide. Herein, dense Ru single-atoms (10.1 wt% of Ru SAs) are anchored on sulfoacid-functionalized hollow mesoporous carbon shells, designed by assembling silica and 8-hydroxyquinoline-modified chitosan (HQ-CTS) through in situ Stöber templating strategy before pyrolysis and acid treatment. Based on X-ray absorption fine structure and computational modeling results, the structure of Ru SAs is determined as RuN4, which is more selective for a transitional glucose hydrogenation to sorbitol than Ru001 of Ru clusters. A lower-energy barrier of 1.21 (0.72) eV is delivered over RuN4 (Ru001) for glucose hydrogenation (isomerization). These Ru SAs are integrated with sulfoacids (SO3H) but resistent against acids, rendering enhanced isosorbide yield in water as compared to Ru clusters, via a one-pot cascade reaction under harsh conditions (220 °C, 6 MPa H2). The elaborately fabricated dense Ru SAs and sulfoacids, achieved by varying the addition time of HQ-CTS during the in situ Stöber templating process, improve the synergism of glucose hydrogenation with cellulose hydrolysis and sorbitol dehydration. This study provides a new idea for rational design of high-performance metal-acid bifunctional catalysts toward one-pot conversion of cellulose to isosorbide.

Mesoporous poly(ionic liquid) solid acid for sequential dehydration of sorbitol to isosorbide

The catalytic conversion of the biomass platform compound sorbitol to isosorbide is an important reaction for the production of relevant renewable chemicals. The development of highly efficient heterogeneous catalyst materials offers promising perspectives for the sorbitol dehydration reaction. The complex competitive reactions, such as degradation and polymerization, are still a major challenge to obtain isosorbide in high yield. In this work, a series of ionic liquid functionalized polymer catalysts, P-[C3/4R]-SF, were successfully prepared by hydrothermal synthesis, which has a high surface area and strong acidity. And the catalysts were fully characterized by the N2 sorption–desorption isotherms, elemental analysis, water adsorption isotherms, FT-IR, TGA and 31P NMR, etc. As a result, the as-prepared P-[C3/4R]-SF catalysts exhibited excellent catalytic activity and stability under mild reaction condition (140 °C, 6 h). The yield of isosorbide is up to 75 %, and it still has good catalytic activity after five cycles. This work provides a synthesis method of ionic liquid functionalized polymer catalyst and its application in sorbitol dehydration reaction.

Role of Calcination Temperature on Isosorbide Production from Sorbitol Dehydration over the Catalyst Derived from Ce(IV) Sulfate

Isosorbide is a multi-purpose chemical that can be produced from renewable resources. Specifically, it has been investigated as a replacement for toxic bisphenol A (BPA) in the production of polycarbonate (PC). In this study, the synthesis of isosorbide by sorbitol dehydration using a cerium-based catalyst derived from calcined cerium (IV) sulfate (300°C, 400°C, 450°C, 500°C, and 650°C) was investigated. The reaction occurred in a high-pressure reactor containing nitrogen gas. Advanced instrumental techniques were applied to analyze the characteristics of the calcined catalyst. The results showed that the calcined catalysts demonstrated different crystalline structures and sulfate species at different temperatures. However, the acidic properties (strength and amount) of the catalyst did not change with the calcination temperature. The cerium (IV) sulfate calcined at 400°C exhibited the best catalytic performance, achieving the highest isosorbide yield (55.7%) and complete conversion of sorbitol at 180°C, 20 bar of N2, and 6 h using CeSO-400. The presence of a sulfate group on the catalyst was the most important factor in determining the catalytic performance of sorbitol dehydration to isosorbide. This work suggests that CeSO-400 catalysts may play an important role in reducing reaction conditions.

Synthesis of sulfated titanium dioxide catalyst for sorbitol dehydration to isosorbide

The use of titania (TiO2) or sulfated titania (SO42-/TiO2) catalysts with different calcination temperatures was studied to study the influence of phase structure on the dehydration of sorbitol to isosorbide. The unsulfated titania calcination temperature and the acid density of the sulfated catalysts significantly influenced catalytic performance. The anatase-phase catalyst calcined at 400 °C and sulfated with 0.1 M sulfuric acid showed excellent performance, full sorbitol conversion, and an isosorbide yield of about 61 % was achieved. This work provides insight into optimizing the phase structure of sulfated catalysts for isosorbide production.

Continuous-Flow Production of Isosorbide from Aqueous-Cellulosic Derivable Feed over Sustainable Heterogeneous Catalysts

Continuous-flow sorbitol dehydration in liquid water was performed on β zeolite (Si/Al molar ratio = 75) with conversion of 94 and 83 mol % isosorbide yield. This efficiency is due to the three-dimension pore architecture, high specific surface area (520 m2 g–1), and Brønsted acid sites of 69 μmol g–1. The pore size of β zeolite (6.6 × 6.7 Å2) is slightly larger than the cross section of sorbitol and isosorbide and enables an efficient diffusion of the reactant and product to/from the pores. Operation in continuous flow allows rapid dehydration of sorbitol to 1,4-sorbitan, after which the latter got converted to isosorbide. The high yield of isosorbide is attributed to the continuous removal of the formed products from the catalyst surface. Finally, direct isosorbide production from aqueous glucose solution via hydrogenation on Ni catalyst supported on nitrogen-doped carbon, followed by dehydration of the formed sorbitol to isosorbide, was pioneered.

Sorbitol Cyclodehydration to Isosorbide Catalyzed by Acidic Carbon Obtained from Reaction By‐Product

AbstractA carbonaceous solid acid catalyst obtained from by‐products of sorbitol dehydration process, was prepared via facile one‐step carbonization and sulfonation method. The results of various characterization technologies showed that as‐prepared acidic carbon bearing ‐SO3H, ‐COOH and ‐OH groups with Brønsted acid sites was effective for solvent‐free dehydration of sorbitol to produce isosorbide. Full complete sorbitol conversion with 72.1% isosorbide yield was achieved at 170 °C after 2 h reaction. Catalyst could be used for three cycles retaining the most of its initial catalytic activity. Importantly, the catalyst and reaction by‐products in this process could be easily recycled and facilely utilized, offering sustainable process in production of isosorbide from sorbitol.

Catalytic Properties of Microporous Zeolite Catalysts in Synthesis of Isosorbide from Sorbitol by Dehydration

As bisphenol A has been found to cause hormonal disturbances, the natural biomaterial isosorbide is emerging as a substitute. In this study, a method for isosorbide synthesis from sorbitol was proposed by dehydration under high temperature and high pressure reaction. Microporous zeolites and Amberlyst 35 solid acids with various acid strengths and pore characteristics were applied as catalysts. In the synthesis of isosorbide from sorbitol, the acidity of the catalyst was the main factor. MOR and MFI zeolite catalysts with high acid strength and small pore size showed low conversion of sorbitol and low yield of isosorbide. On the other hand, the conversion of sorbitol was high in BEA zeolite with moderate acid strength. Amberlyst 35 solid acid catalysts showed a relatively high conversion of sorbitol, but low yield of isosorbide. The Amberlyst 35 solid acid catalyst without micropores did not show any inhibitory effects on the production of by-products. However, in the BEA zeolite catalyst, which has a relatively large pore structure compared with the MOR and MFI zeolites, the formation of by-products was suppressed in the pores, thereby improving the yield of isosorbide.

Solvent-Free Production of Isosorbide from Sorbitol Catalyzed by a Polymeric Solid Acid.

A series of polymeric solid acid catalysts (PDSF-x) is prepared by grafting strong electron-withdrawing groups (-SO2 CF3 ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor synthesized hydrothermally. The effect of acid strength on sorbitol dehydration is investigated. The textural properties, acidity, and hydrophobicity are characterized by using Brunauer-Emmett-Teller analysis, elemental analysis, and contact angle tests. The results of FTIR spectroscopy and X-ray photoelectron spectroscopy show that both -SO3 H and -SO2 CF3 are grafted onto the polymer network. We used solid-state 31 P NMR spectroscopy to show that the acid strength of PDSF-x is enhanced significantly compared with that of PDS, especially for PDSF-0.05. As a result, PDSF-0.05 exhibits the highest isosorbide yield up to 80 %, a good turnover frequency of 231.5 h-1 (compared to other catalysts), and excellent cyclic stability, which is attributed to its large specific surface area, appropriate acid strength, hydrophobicity, and stable framework structure. In addition, a plausible reaction pathway and kinetic analysis are proposed.

Heterogeneous cyclization of sorbitol to isosorbide catalyzed by a novel basic porous polymer-supported ionic liquid

In this study, heterogeneous cyclization of sorbitol to isosorbide under basic condition was realized for the first time with a novel porous polymer-supported ionic liquid as catalyst. These polymer-supported ILs were synthesized through the suspension polymerization of 4-vinylbenzyl chloride and divinylbenzene, followed by a quaternization reaction. As compared to those of non-porous, the porous polymers had high specific surface area and large number of active sites. Consequently, they exhibited excellent catalytic activity in the cyclization of sorbitol with dimethylcarbonate (DMC) to isosorbide. As a result, a high conversion of sorbitol (99%) was achieved with 83% yield of isosorbide under optimized conditions. Importantly, the catalysts could be easily separated by decantation and reused for five times without obvious loss of catalytic activity.

Mesoporous Al-promoted sulfated zirconia as an efficient heterogeneous catalyst to synthesize isosorbide from sorbitol

Mesoporous aluminum-promoted sulfated zirconia (named as mAl-SZ) was directly prepared by grind method, and firstly used to catalyze the solvent-free dehydration of sorbitol to isosorbide. The physicochemical properties of as-prepared catalysts were characterized by FT-IR, TGA, XRD, N2 sorption, NH3-TPD and pyridine-infrared (IR) spectroscopy techniques in order to elucidate the relevance of the catalyst properties and the catalytic performance. It was found that the catalysts prepared by grind method possessed mesoporous structures with high surface area, pure tetragonal phase as well as high sulfur contents, which were advantage to eliminate diffusion limitation and generate abundant acidic sites, especially Brönsted acidic sites. Furthermore, aluminum promoters could contribute to the considerable increase of the strong acidic sites and ratio of Brönsted to Lewis acidic sites. Consequently, the mesoporous sulfated zirconia with 6 mol% Al-promoter (6Al-SZ) attained porous structure with improved acidic properties, thus showing the optimal catalytic behavior. The full sorbitol conversion with 73% isosorbide selectivity was achieved under milder conditions (175 °C, 2 h) than those of similar type of catalysts. In addition, the 6Al-SZ exhibited favorable reusability with insignificant drop in isosorbide yield during five reaction cycles.

Synthesis of isosorbide from sorbitol in water over high-silica aluminosilicate zeolites

Dehydration of sorbitol to isosorbide in water was studied using various types of aluminosilicate zeolites as heterogeneous catalyst. Among the zeolite catalysts tested, the *BEA-type aluminosilicate zeolite (beta) showed a remarkably high catalytic performance; especially, beta zeolite with the Si/Al ratio of 75, designated as beta(75), gave an isosorbide yield as high as 80%. We have found that the three-dimensional large pore structure is favorable for enhancing the diffusion of sorbitol and the products. In addition, beta with a low Al content exhibited a higher catalytic activity than that with a high Al content, despite the small number of acid sites. The reason for this high catalytic activity is ascribed to hydrophobicity of the catalyst surface. Hydrothermal stability is another critical factor in determining the catalytic performance. The influence of reaction parameters such as temperature and the catalyst amount was investigated. The beta(75) proved to be reusable without loss of activity after calcination at 550°C.

One-pot conversion of cellulose to isosorbide using supported metal catalysts and ion-exchange resin

One-pot conversion of cellulose to isosorbide was investigated by supported metal catalysts and ion-exchange resin in water. The maximum isosorbide yield using supported platinum catalysts and Amberlyst 70 was less than 30%. The isosorbide yield drastically increased with supported ruthenium catalysts instead of supported platinum catalysts and it also increased with the loading of ruthenium on carbon support. One-pot conversion of cellulose to isosorbide by 4wt.% ruthenium catalyst and Amberlyst 70 proceeded with isosorbide yield of 55.8%.

Dehydration of sorbitol to isosorbide over H-beta zeolites with high Si/Al ratios

H-beta zeolite with a Si/Al ratio of 75 uniquely shows high catalytic activity for the dehydration of sorbitol, giving a 76% yield of isosorbide at 400 K over 2 h.

Role of acid sites and selectivity correlation in solvent free liquid phase dehydration of sorbitol to isosorbide

A number of Brönsted acids (methanesulfonic acid, p-toluene sulfonic acid, triflic acid, sulfamic acid, citric acid, NaHSO4, and boric acid) and Lewis acids (metal sulfate/triflates) were employed in solvent free dehydration of sorbitol and their influence on anhydroalcohols selectivity has been investigated. The outcome indicated that all the acid catalysts produced first mono-dehydrated product sorbitan followed by second dehydration of 1,4-sorbitan to isosorbide. However, the formation and yield isosorbide were found to depend on the nature of acid sites and their acidic strength. The Brönsted acids are more efficient to convert sorbitol to isosorbide than Lewis acids. The Brönsted acids having lower pKa value (i.e. strong acid) exhibited high catalytic activity as well as yield of isosorbide. In the case of Lewis acids, the catalytic activity and selectivity were radically depended on which metal used and their stability during the reaction. The water formed during reaction induced Brönsted acidity on Lewis acid metal site. The Lewis-assisted Brönsted acid site enabled high yield of isosorbide up to 70% at moderate temperature (160°C).

Enhanced catalytic performance in dehydration of sorbitol to isosorbide over a superhydrophobic mesoporous acid catalyst

A superhydrophobic mesoporous polymer-based acid catalyst (P-SO3H) was synthesized from solvothermal co-polymerization. The N2 sorption isotherms indicate the rich porosity of P-SO3H, confirmed by the TEM image. The IR spectra indicate the presence of sulfonic acid groups. Interestingly, P-SO3H gives contact angle of water droplet on the sample surface at 154°, suggesting its superhydrophobicity. More importantly, P-SO3H is highly efficient catalyst for dehydration of sorbitol to isosorbide, giving sorbitol conversion higher than 99.0% and isosorbide yield at 87.9%. In addition, P-SO3H exhibits excellent recyclability. After recycles for 5 times, the isosorbide yield is still 77.7%. In contrast, conventional acid catalyst of Amberlyst-15 shows the yield at only 15.4% after recycles for 3 times. The unique catalytic properties are reasonably related to the superhydrophobicity and porosity of P-SO3H. The sample large porosity offers a high degree of the exposed acidic sites to the reactants, and the sample superhydrophobicity would keep the water formed in the dehydration away from the catalyst, promoting the reaction equilibrium. As a result, the catalytic performance in dehydration of sorbitol to isosorbide over the superhydrophobic P-SO3H catalyst is significantly enhanced, compared with conventional acid catalyst of Amberlyst-15.

Conversion of Cellulose into Isosorbide over Bifunctional Ruthenium Nanoparticles Supported on Niobium Phosphate

Considerable effort has been applied to the development of new processes and catalysts for cellulose conversion to valuable platform chemicals. Isosorbide is among the most interesting products as it can be applied as a monomer and building block for the future replacement of fossil resource-based products. A sustainable method of isosorbide production from cellulose is presented in this work. The strategy relies on a bifunctional Ru catalyst supported on mesoporous niobium phosphate in a H2 atmosphere under pressure without further addition of any soluble acid. Over 50 % yield of isosorbide with almost 100 % cellulose conversion can be obtained in 1 h. The large surface area, pore size, and strong acidity of mesoporous niobium phosphate promote the hydrolysis of cellulose and dehydration of sorbitol; additionally, the appropriate size of the supported Ru nanoparticles avoids unnecessary hydrogenolysis of sorbitol. Under a cellulose/catalyst mass ratio of 43.3, the present bifunctional catalyst could be stably used up to six times, with its mesoporous structure well preserved and without detectable Ru leaching into the reaction solution.

Catalytic production of isosorbide from cellulose over mesoporous niobium phosphate-based heterogeneous catalysts via a sequential process

The catalytic valorization of cellulose as feedstock for the large-scale production of liquid fuels and value-added chemicals is currently subject to extensive research. Isosorbide as an important intermediate for the synthesis of a wide range of pharmaceuticals, chemicals and polymers, its efficient production from natural cellulose is very important. Here we report a two-step sequential process where cellulose is firstly depolymerized with Ru/NbOPO4-pH2 catalyst via hydrolysis and hydrogenation and then the resultant sorbitol and sorbitan are directly converted into isosorbide in the presence of solid acid catalyst. The influence of different solid catalysts is investigated in the direct dehydration of sorbitol to isosorbide and finds that NbOPO4-pH2 with the highest acid amount shows the best performance and is used in the sequential process. The reaction conditions (especially reaction temperature and reaction time) are systematically investigated and 56.7% isosorbide yield is obtained under optimal conditions, which is impressive compared with other systems reported with homogeneous or semi-heterogeneous catalysts. This effective catalytic system avoids the use of liquid acid and exhibits excellent cycling stability.

Conversion of (Ligno)Cellulose Feeds to Isosorbide with Heteropoly Acids and Ru on Carbon

The catalytic valorization of cellulose is currently subject of intense research. Isosorbide is among the most interesting products that can be formed from cellulose as it is a potential platform molecule and can be used for the synthesis of a wide range of pharmaceuticals, chemicals, and polymers. A promising direct route from cellulose to isosorbide is presented in this work. The strategy relies on a one-pot bifunctional catalytic concept, combining heteropoly acids, viz. H(4)SiW(12)O(40), and redox catalysts, viz. commercial Ru on carbon, under H(2) pressure. Starting from pure microcrystalline cellulose, a rapid conversion was observed, resulting in over 50% isosorbide yield. The robustness of the developed system is evidenced by the conversion of a range of impure cellulose pulps obtained by organosolv fractionation, with isosorbide yields up to 63%. Results were compared with other (ligno)cellulose feedstocks, highlighting the importance of fractionation and purification to increase reactivity and convertibility of the cellulose feedstock.