Selective Conversion of Glucose to 5-Hydroxymethylfurfural by Using L-Type Zeolites with Different Morphologies

A surface modification strategy to prepare hierarchical Beta molecular sieves for glucose dehydration

In order to balance the contradiction between mesopore introduction and loss of microporosity, a surface modification strategy is proposed by selectively adsorbing organic alkaline molecules on Beta molecular sieves before NaOH etching. Organic alkaline molecules adsorb on framework aluminum sites and the protective function of organic bases is affected by the adsorption configuration and physical barrier effect of organic bases. Organic alkaline molecules serve as a protective agent to increase the bond length of Al-O bonds. Therefore, the as-synthesized hierarchical Beta molecular sieves have more acid sites due to the preservation of aluminum atoms. When employed as catalysts in the dehydration reaction of glucose, 5-hydroxymethylfurfural (5-HMF) is obtained under the synergistic effect of Brønsted and Lewis acid sites. The unique contribution is to realize the porosity regulation and alleviate the acidity loss of Beta molecular sieves. These results are important to broaden the application fields of aluminum-silicon molecular sieves especially for large molecule-engaged acid catalyzed reactions.

Mechanoresponsive diselenide-crosslinked microgels with programmed ultrasound-triggered degradation and radical scavenging ability for protein protection

In the context of controlled delivery and release, proteins constitute a delicate class of cargo requiring advanced delivery platforms and protection. We here show that mechanoresponsive diselenide-crosslinked microgels undergo controlled ultrasound-triggered degradation in aqueous solution for the release of proteins. Simultaneously, the proteins are protected from chemical and conformational damage by the microgels, which disintegrate to water-soluble polymer chains upon sonication. The degradation process is controlled by the amount of diselenide crosslinks, the temperature, and the sonication amplitude. We demonstrate that the ultrasound-mediated cleavage of diselenide bonds in these microgels facilitates the release and activates latent functionality preventing the oxidation and denaturation of the encapsulated proteins (cytochrome C and myoglobin) opening new application possibilities in the targeted delivery of biomacromolecules.

Mechanoresponsive diselenide-crosslinked microgels undergo controlled ultrasound-triggered degradation and can be used for protein delivery due to their dual protection properties acting as radical scavengers and conformation stabilizers.

Sustainable Catalytic Conversion of Biomass for the Production of Biofuels and Bioproducts

Biomass, in its many forms—oils and fats, lignocellulose, algae, etc [...]

Metal Chlorides Grafted on SAPO-5 (MClx/SAPO-5) as Reusable and Superior Catalysts for Acylation of 2-Methylfuran Under Non-Microwave Instant Heating Condition

Highly active metal chlorides grafted on silicoaluminophosphate number 5, MClx/SAPO-5 (M = Cu, Co, Sn, Fe and Zn) catalysts via simple grafting of respective metal chlorides (MClx) onto SAPO-5 are reported. The study shows that thermochemical treatment after grafting is essential to ensure the formation of chemical bondings between MClx and SAPO-5. In addition, the microscopy, XRD and nitrogen adsorption analyses reveal the homogeneous distribution of MClx species on the SAPO-5 surface. Furthermore, the elemental microanalysis confirms the formation of Si–O–M covalent bonds in ZnClx/SAPO-5, SnClx/SAPO-5 and FeClx/SAPO-5 whereas only dative bondings are formed in CoClx/SAPO-5 and CuClx/SAPO-5. The acidity of MClx/SAPO-5 is also affected by the type of metal chloride grafted. Thus, their catalytic behavior is evaluated in the acid-catalyzed acylation of 2-methylfuran under novel non-microwave instant heating conditions (90–110 °C, 0–20 min). ZnClx/SAPO-5, which has the largest amount of acidity (mainly Lewis acid sites), exhibits the best catalytic performance (94.5% conversion, 100% selective to 2-acetyl-5-methylfuran) among the MClx/SAPO-5 solids. Furthermore, the MClx/SAPO-5 solids, particularly SnClx/SAPO-5, FeClx/SAPO-5 and ZnClx/SAPO-5, also show more superior catalytic performance than common homogeneous acid catalysts (H2SO4, HNO3, CH3COOH, FeCl3, ZnCl2) with higher reactant conversion and catalyst reusability, thus offering a promising alternative for the replacement of hazardous homogeneous catalysts in Friedel–Crafts reactions.

Effects of Synthesis Parameters on Crystallization Behavior of K-MER Zeolite and Its Morphological Properties on Catalytic Cyanoethylation Reaction

MER-type zeolite is an interesting microporous material that has been widely used in catalysis and separation. By carefully controlling the synthesis parameters, a procedure to synthesize K-MER zeolite crystals with various morphologies has been developed. The silica, water and mineralizer content in the synthesis gel, as well as crystallization time and temperature, have a profound impact on the crystallization kinetics, resulting in zeolite solids with various degrees of crystallinity, crystal sizes and shapes. K-MER zeolite crystals with nanorod, bullet-like, prismatic and wheatsheaf-like morphologies have been successfully obtained. The catalytic performances of the K-MER zeolites in cyanoethylation of methanol, under novel non-microwave instant heating, have been investigated. The zeolite in nanosize form shows the best catalytic performance (94.1% conversion, 100% selectivity) while the bullet-like zeolite gives poorest catalytic performance (44.2% conversion, 100% selectivity).

Transformation of remnant algal biomass to 5-HMF and levulinic acid: influence of a biphasic solvent system

The primary commercial product from the green microalgae Dunaliella salina is β-carotene. After extracting the lipophilic fraction containing this red-orange pigment, an algal residue remains. As the carotenogenesis is induced by light stress with simultaneous nitrogen depletion, the protein content is low and the remnant is comprised largely of storage carbohydrates. In this work, we transformed the defatted remnant directly to the platform chemicals, 5-hydroxy methyl furfural (5-HMF) and levulinic acid (LA), without previous purification or any pretreatment. The batch experiments were carried out in an autoclave under biphasic solvent conditions at 453 K for 1 h using acidic ZSM-5 zeolite as a heterogeneous catalyst. Mixtures of methyl isobutyl ketone (MIBK/H₂O) or tetrahydrofuran (THF/H₂O/NaCl) with water were used to create the biphasic reactor conditions. The biphasic reaction mixtures helped to increase the 5-HMF yield and simultaneously mitigated the formation of insoluble humins. The carbon yields of 5-HMF and of LA in the MIBK/H₂O biphasic system without NaCl were 13.9% and 3.7%, respectively. The highest carbon yield of 5-HMF (34.4%) was achieved by adding NaCl to the reaction mixture containing THF/H₂O. The experimentally measured partition ratios of 5-HMF between the two liquid phases were compared to the predictions calculated by the computational method COSMO-RS, which is a quantum chemistry-based method to predict the thermodynamic equilibria of liquid mixtures and the solubilities. The COSMO-RS predicted partition ratios of 5-HMF were in line with the experimentally measured ones.

Defatted algal remnant is transformed to 5-HMF and LA.