Highly Efficient Iridium-Iron-Molybdenum Catalysts Condensed on Boron Nitride for Biomass-Derived Diols' Hydrogenolysis to Secondary Monoalcohols.

A trade-off of activity-selectivity exists in primary C-O hydrogenolysis of biomass-derived diols to secondary alcohols over bimetallic catalysts, especially the combination of noble metal and early transition metal in the metallic state and metal oxide state, respectively. Herein, the combination of high surface concentration of boron nitride (BN)-supported metals and the addition of Mo as third metal broke the trade-off. High yields (>50%) of secondary alcohols were obtained with robust productivity up to 25-fold based on Ir over Ir-Fe-Mo/BN (Ir = 20 wt %, Fe/Ir = 0.

Formation of paired Ga sites in CHA-type zeolite frameworks a transcription-induced method.

Paired Ga sites represented by the Ga-O-Si-O-Ga sequence were firstly formed intentionally in CHA-type zeolite frameworks the transcription of pre-formed paired Ga species in a Ga-rich amorphous silica-gallia under seed-assisted hydrothermal conditions. Such paired Ga sites behaved as ion-exchange sites for capturing divalent cation, Co.

Direct Esterification of Alkylcarbamic Acids with Alcohols over CeO Catalyst.

Alkylcarbamic acids, which are easily produced via chemical absorption of CO into amines, have a great potential to be substrates for producing value-added chemicals. In this research, the esterification of various alkylcarbamic acids with alcohols into alkyl N-alkylcarbamates was demonstrated by using a heterogeneous catalyst as well as the corresponding amine additives. In the model reaction, the esterification of benzylcarbamic acid (BZA-CA) and methanol (MeOH), the target product of methyl N-benzylcarbamate was obtained in 64 % CO -based yield at 413 K in 12 h over a CeO catalyst, which also exhibited good reusability.

Comparative Study between 2-Furonitrile and 2-Cyanopyridine as Dehydrants in Direct Synthesis of Dialkyl Carbonates from CO and Alcohols over Cerium Oxide Catalyst.

The shift of equilibrium by removing water with nitrile dehydrants is crucial for CeO -catalyzed synthesis of dialkyl carbonates from CO and alcohols. Two nitriles - 2-cyanopyridine and 2-furonitrile - were previously found as effective dehydrants, yet their detailed comparison as well as exploration of potential of 2-furonitrile remain insufficient. Herein, the performance of 2-cyanopyridine and 2-furonitrile was compared in the synthesis of various dialkyl carbonates.

Fluoride-free synthesis of high-silica CHA-type aluminosilicates by seed-assisted aging treatment for starting gel.

High-silica CHA-type aluminosilicates (Si/Al molar ratio >100) were synthesized hydrothermally in the absence of fluoride media, where the seed-assisted aging treatment played an important role on the crystallization. These aluminosilicates showed a long catalytic lifetime with high selectivity toward lower olefins in the methanol-to-olefins reaction.

Deoxydehydration of Biomass-Derived Polyols Over Silver-Modified Ceria-Supported Rhenium Catalyst with Molecular Hydrogen.

Olefin production from polyols via deoxydehydration (DODH) was carried out over Ag-modified CeO -supported heterogeneous Re catalysts with H as a reducing agent. Both high DODH activity and low hydrogenation ability for C=C bonds were observed in the reaction of erythritol, giving a 1,3-butadiene yield of up to 90 % under "solvent-free" conditions. This catalyst is applicable to other substrates such as methyl glycosides (methyl α-fucopyranoside: 91 % yield of DODH product; methyl β-ribofuranoside: 88 % yield), which were difficult to be converted to the DODH products over the DODH catalysts reported previously.

Transcription-induced formation of paired Al sites in high-silica CHA-type zeolite framework using Al-rich amorphous aluminosilicate.

The paired Al species pre-formed in Al-rich amorphous aluminosilicates were transcribed into high-silica CHA-type zeolite frameworks under hydrothermal conditions, which offers a new approach to creating paired Al sites in zeolite frameworks. This Al-pair-rich CHA exhibited a higher Sr uptake than the control CHA zeolite synthesized by the conventional procedure.

CeO-Catalyzed Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate.

CeO acted as an effective and reusable heterogeneous catalyst for the direct synthesis of 2-imidazolidinone from ethylenediamine carbamate (EDA-CA) without further addition of CO in the reaction system. 2-Propanol was the best solvent among the solvents tested from the viewpoint of selectivity to 2-imidazolidinone, and the use of an adequate amount of 2-propanol provided high conversion and selectivity for the reaction. This positive effect of 2-propanol on the catalytic reaction can be explained by the solubility of EDA-CA in 2-propanol under the reaction conditions and no formation of solvent-derived byproducts.

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions.

The adsorption of POMs on Rh/SiO in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO at 393-473 K under 1 MPa of H. Monovanadium-substituted silicotungstate, α-SiVWO (SiVW), was more readily adsorbed than nonsubstituted silicotungstate, α-SiWO (SiW).

Organic Structure-Directing Agent-Free Synthesis of Mordenite-Type Zeolites Driven by Al-Rich Amorphous Aluminosilicates.

Mordenite (MOR)-type zeolites with a Si/Al molar ratio of up to 13 with crystallite sizes of ca. 60 nm were successfully synthesized from Al-rich aluminosilicates with a Si/Al ratio of 2 and additional SiO under seed-assisted hydrothermal conditions for 6 h or longer without any organic structure-directing agents (OSDAs). In stark contrast, under the same hydrothermal conditions for 6 h, control experiments using starting reagent(s), such as Al-poor aluminosilicate, pure SiO, tetraethyl orthosilicate, and Al(NO), all of which are typically employed for zeolite synthesis, failed to yield MOR-type zeolites.

Magnetic field induced uniaxial alignment of the lyotropic liquid-crystalline PMMA-grafted FeO nanoplates with controllable interparticle interaction.

Magnetite (FeO) nanoplates with a hexagonal platelet shape were synthesized by two steps: hydrothermal synthesis of iron(iii) oxide (α-FeO) nanoplates followed by wet chemical reduction of the α-FeO nanoplates. Then, poly(methyl methacrylate) (PMMA) chains were grafted onto the surface of the hexagonal FeO nanoplates (F) surface-initiated atom transfer radical polymerization (SI-ATRP), which ensures dispersion stability in organic solvents and ionic liquids. After mixing with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][NTf ]), a representative ionic liquid, the resulting PMMA-modified F were found to show good lyotropic liquid-crystalline (LC) behaviour in [Emim][NTf ] and to exhibit a fast response to the application of an external magnetic field.

Selective Sequestration of Aromatics from Aqueous Mixtures with Sugars by Hydrophobic Molecular Calixarene Cavities Grafted on Silica.

The separation of aromatic contaminants from sugar-aromatic aqueous mixtures is required in second-generation biorefineries because aromatic compounds deactivate (bio)catalysts typically involved in upgrading lignocellulosic biomass to fuels and chemicals. This separation remains challenging, however, because of the degree of molecular recognition needed to sequester dilute aromatic impurities from concentrated sugar streams. Herein, we demonstrate that hydrophobic cavities of p- tert-butylcalix[4]arene macrocycles grafted on amorphous silica (calix/SiO) perform this separation selectively and efficiently by acting as selective molecular hosts that adsorb aromatic compounds (5-hydroxymethylfurfural, vanillin, and vanillic acid) while excluding monomeric sugar (glucose chosen as a prototypical model) in aqueous mixtures.

Insights into Supramolecular Sites Responsible for Complete Separation of Biomass-Derived Phenolics and Glucose in Metal-Organic Framework NU-1000.

The molecular origins of adsorption of lignin-derived phenolics to metal-organic framework NU-1000 are investigated from aqueous solution as well as in competitive mode with glucose present in the same aqueous mixture. A comparison of adsorption equilibrium constants (K) for phenolics functionalized with either carboxylic acid or aldehyde substituents demonstrated only a slight increase (less than a factor of 6) for the former according to both experiments and calculations. This small difference in K between aldehyde and carboxylic-acid substituted adsorbates is consistent with the pyrene unit of NU-1000 as the adsorption site, rather than the zirconia nodes, while at saturation coverage, the adsorption capacity suggests multiple guests per pyrene.

Complete furanics-sugar separations with metal-organic framework NU-1000.

Metal-organic framework NU-1000 selectively adsorbs furanics, while completely excluding the adsorption of monomeric sugars from the same aqueous mixture. The highly refined degree of molecular recognition exhibited by NU-1000 is exemplified with it selectively adsorbing 5-hydroxymethylfurfural, even in the presence of up to a 300-fold excess of glucose in solution.

Unprecedented selectivity in molecular recognition of carbohydrates by a metal-organic framework.

Metal-organic framework (MOF) material NU-1000 adsorbs dimers cellobiose and lactose from aqueous solution, in amounts exceeding 1250 mg gNU-1000(-1) while completely excluding the adsorption of the monomer glucose, even in a competitive mode with cellobiose. The MOF also discriminates between dimers consisting of α and β linkages, showing no adsorption of maltose. Electronic structure calculations demonstrate that key to this selective molecular recognition is the number of favorable CH-π interactions made by the sugar with pyrene units of the MOF.

Catalytic Depolymerization of Chitin with Retention of N-Acetyl Group.

Chitin, a polymer of N-acetylglucosamine units with β-1,4-glycosidic linkages, is the most abundant marine biomass. Chitin monomers containing N-acetyl groups are useful precursors to various fine chemicals and medicines. However, the selective conversion of robust chitin to N-acetylated monomers currently requires a large excess of acid or a long reaction time, which limits its application.

Entropically favored adsorption of cellulosic molecules onto carbon materials through hydrophobic functionalities.

Carbon-based materials have attracted interest as high-performance catalysts for the aqueous-phase conversion of cellulose. The adsorption of β-glucans plays a crucial role in the catalytic performance of carbons, although the primary driving force and details of the adsorption process remain unclear. This study demonstrates that adsorption occurs at hydrophobic sites on the carbon surface and that hydrophilic groups are not involved.