More Like this

1. Three-step cascade over a single catalyst: synthesis of 5-(ethoxymethyl)furfural from glucose over a hierarchical lamellar multi-functional zeolite catalyst

   https://doi.org/10.1039/C8TA01242C  

   Bai, Yuanyuan; Wei, Lu; Yang, Mengfei; Chen, Huiyong; Holdren, Scott; Zhu, Guanghui; Tran, Dat T.; Yao, Chunli; Sun, Runcang; Pan, Yanbo; et al (January 2018, Journal of Materials Chemistry A)

   The synthesis of hierarchical lamellar zeolites with a controlled meso-/microporous morphology and acidity is an expanding area of research interest for a wide range of applications. Here, we report a one-step synthesis of a hierarchical meso-/microporous lamellar MFI–Sn/Al zeolite ( i.e. , containing both Lewis acidic Sn- and Al-sites and a Brønsted acidic Al–O(H)–Si site) and its catalytic application for the conversion of glucose into 5-(ethoxymethyl)furfural (EMF). The MFI–Sn/Al zeolite was prepared with the assistance of a diquaternary ammonium ([C 22 H 45 –N + (CH 3 ) 2 –C 6 H 12 –N + (CH 3 ) 2 –C 6 H 13 ]Br 2− , C 22-6-6 ) template in a composition of 100SiO 2 /5C 22-6-6 /18.5Na 2 O/ x Al 2 O 3 / y SnO 2 /2957H 2 O ( x = 0.5, 1, and 2; y = 1 and 2, respectively). The MFI–Sn/Al zeolites innovatively feature dual meso-/microporosity and dual Lewis and Brønsted acidity, which enabled a three-step reaction cascade for EMF synthesis from glucose in ethanol solvent. The reaction proceeded via the isomerization of glucose to fructose over Lewis acidic Sn sites and the dehydration of fructose to 5-hydroxymethylfurfural (HMF) and then the etherification of HMF and ethanol to EMF over the Brønsted acidic Al–O(H)–Si sites. The co-existence of multiple acidities in a single zeolite catalyst enabled one-pot cascade reactions for carbohydrate upgrading. The dual meso-/microporosity in the MFI–Sn/Al zeolites facilitated mass transport in processing of bulky biomass molecules. The balance of both types of acidity and meso-/microporosity realized an EMF yield as high as 44% from the glucose reactant. 

   more » « less
2. Hydroxy sulfonic acid catalyzed hydrolysis of cellulose

   https://doi.org/10.1080/17597269.2023.2221969  

   Amarasekara, Ananda S.; Nwankwo, Victor C.; Fernando, Harshica (June 2023, Biofuels)

   Development of efficient catalytic methods for the hydrolysis of cellulose is a major research challenge in sustainable biofuel and polymer areas. In this study five hydroxy sulfonic acids were studied as simple model compounds for cellulase enzyme for the hydrolysis of cellulose. The catalytic activities were measured by analysis of total reducing sugar (TRS) yields produced in a series of reactions carried out at 150–190 °C using 0.050 M aqueous hydroxy sulfonic acid solutions. The highest catalytic activity was observed with isethionic acid, producing 62.7% TRS yield at 180 °C after 4 hr. In the second phase of the work, Density Functional Theory (DFT) calculations were used to study the interactions between hydroxy sulfonic acids and cellulose model compound D-cellobiose to supplement the experimental results. The D-cellobiose – hydroxy sulfonic binding energies and the distance between glycosidic oxygen and -SO3H acidic H were evaluated and the -SO3H to glycosidic oxygen distance was identified as the more important parameter co-related to the catalytic activity. The isethionic acid with highest cellulose hydrolysis activity showed the shortest -SO3H to glycosidic oxygen distance of 1.744 Å. 

   more » « less
3. The Effect of Dicarboxylic Acid Catalyst Structure on Hydrolysis of CelluloseModel Compound D-Cellobiose in Water

   https://doi.org/10.2174/2213337208666211129090444  

   Fernando, Harshica; Amarasekara, Ananda S. (June 2022, Current Organocatalysis)

   Background:Polycarboxylic acids are of interest as simple mimics for cellulase enzyme catalyzed depolymerization of cellulose. In this study, DFT calculations were used to investigate the effect of structure on dicarboxylic acid organo-catalyzed hydrolysis of cellulose model compound D-cellobiose to D-glucose. Methods:Binding energy of the complex formed between D-cellobiose and acid (Ebind), as well as glycosidic oxygen to dicarboxylic acid closest acidic H distance were studied as key parameters affecting the turn over frequency of hydrolysis in water. Result:α-D-cellobiose - dicarboxylic acid catalyst down face approach showed high Ebind values for five of the six acids studied; indicating the favorability of down face approach. Maleic, cis-1,2-cyclohexane dicarboxylic, and phthalic acids with the highest catalytic activities showed glycosidic oxygen to dicarboxylic acid acidic H distances 3.5-3.6 Å in the preferred configuration. Conclusion:The high catalytic activities of these acids may be due to the rigid structure, where acid groups are held in a fixed geometry. 

   more » « less
4. Cage effects control the mechanism of methane hydroxylation in zeolites

   https://doi.org/10.1126/science.abd5803  

   Snyder, Benjamin E.; Bols, Max L.; Rhoda, Hannah M.; Plessers, Dieter; Schoonheydt, Robert A.; Sels, Bert F.; Solomon, Edward I. (July 2021, Science)

   null (Ed.)

   Catalytic conversion of methane to methanol remains an economically tantalizing but fundamentally challenging goal. Current technologies based on zeolites deactivate too rapidly for practical application. We found that similar active sites hosted in different zeolite lattices can exhibit markedly different reactivity with methane, depending on the size of the zeolite pore apertures. Whereas zeolite with large pore apertures deactivates completely after a single turnover, 40% of active sites in zeolite with small pore apertures are regenerated, enabling a catalytic cycle. Detailed spectroscopic characterization of reaction intermediates and density functional theory calculations show that hindered diffusion through small pore apertures disfavors premature release of CH 3 radicals from the active site after C-H activation, thereby promoting radical recombination to form methanol rather than deactivated Fe-OCH 3 centers elsewhere in the lattice. 

   more » « less
5. Effect of Cellulose Nanofibril Size on Adsorption Behavior of 3-D Cellulose Hydrogels

   https://doi.org/10.1007/s11270-025-08323-1  

   Nan, Yufei; Gomez-Maldonado, Diego; Bello, Fatimatu; Zhu, J Y; Peresin, Maria Soledad (November 2025, Water, Air, & Soil Pollution)

   AbstractWith the development of cellulose nanofibril (CNF)-based adsorbents, the influence of particle size on adsorption capability has become increasingly recognized. In this study, endoglucanase FiberCare® was utilized to decrease fibril size of TEMPO-oxidized cellulose nanofibrils (TCNFs) without changing carboxyl groups content of the resulting TCNFs. Average fibril length decreased by 27.3% (from 508.7 nm to 369.4 nm) after enzymatic hydrolysis for 12 h and further decreased by 35.4% (to 328.2 nm) after 24 h. Meanwhile, the average fibril diameter decreased 20.2% (from 56.8±16.3 to 45.3±14.3) after 12 h of hydrolysis, further reduced by 32.6% (to 38.3±13.1 nm) after 24 h. Carboxyl group content remained unchanged. Zeta potential of the TCNFs was increased by 5.5 mV after 24 h hydrolysis due to the exposure of more hydroxyl groups as fibril size decreases. TCNF hydrogel (from 12 h hydrolyzed) showed 20.3% increase in adsorption of cationic methylene blue dyes (from 64 mg/g to 77 mg/g) compared to untreated samples. However, further fibril size reduction after 24 h hydrolysis did not improve adsorption capability. Kinetic analysis using pseudo-second-order kinetic model and intra-particle diffusion model revealed no change in the adsorption mechanism, though the overall adsorption rate increased. This study highlights that reducing fibril size can enhance both adsorption capacity and rate, offering guidance for the design of CNF-based adsorbents. Graphical Abstract 

   more » « less