Efficient Heterogeneous Catalyst For Conversion Research Articles

Acid and magnetic modifications of gum arabic as a dual approach for preparation of an efficient heterogeneous catalyst for conversion of fructose to value-added furanic compound

Acid and magnetic modifications of gum arabic as a dual approach for preparation of an efficient heterogeneous catalyst for conversion of fructose to value-added furanic compound

Construction of silsesquioxane and phosphinum‐based ionic porous hypercrosslinked polymers for efficient heterogeneous catalytic CO2 cycloaddition

AbstractIn this work, we reported a facile one‐pot route to construct polyhedral oligomeric silsesquioxane (POSS) and phosphonium‐based ionic porous hypercrosslinked polymers (denoted as P‐iPHCPs) with multiple catalytic active sites, which could be regarded as efficient heterogeneous catalysts for the conversion of carbon dioxide (CO2) to highly value‐added cyclic carbonates. The targeted polymers P‐iPHCPs were prepared from a rigid building block octavinylsilsesquioxane (VPOSS) and a low‐cost commercially available organic ionic salt methyltriphenylphosphonium bromide ([Ph3PMe]Br) by the AlCl3‐catalyzed Friedel‐Crafts reaction. The series of polymers P‐iPHCPs that synthesized by different molar ratios of VPOSS to [Ph3PMe]Br possess hierarchical micro/mesoporous structures with high surface areas ranging from 376 to 429 m2 g−1 and behave the flower‐like nano‐morphology. Especially, the desired multiple active sites involved the mixed anions including free Cl−, Br− anions and the in‐situ formed metal‐halogen complex anion [AlCl3Br]− within phosphonium segments, and the enriched POSS‐derived SiOH hydrogen bond donor (HBD) groups that derived from the breakage of POSS cages during the synthetic process. The typical polymer P‐iPHCP‐14 has the aforementioned nucleophilic‐electrophilic multiple catalytic active sites, which was regarded as an efficient recyclable heterogeneous catalyst for synergistic catalytic conversion of CO2 with various epoxides into cyclic carbonates under mild conditions.

Integration of multifunctionalities on ionic liquid-anchored MIL-101(Cr): A robust and efficient heterogeneous catalyst for conversion of CO2 into cyclic carbonates

Abstract The rational integration of multiple functional components into a suitable matrix material is a promising strategy for constructing efficient catalysts for specific applications. Herein, a novel Zn-containing imidazolium bromide was facilely anchored onto MIL-101(Cr) (MIL-101(Cr)-(AIm)2ZnBr2) via a coordination bond between the amino group in ionic liquid (IL) moiety and unsaturated Cr3+ center in MOF framework, which catalyzed the efficient synthesis of cyclic carbonates through the cycloaddition of CO2 and epoxides. The as-prepared MIL-101(Cr)-(AIm)2ZnBr2 groups the essential factors that facilitate the superb cycloaddition efficiency, involving: (1) Cr (III) and Zn (II) working as Lewis acid sites for polarizing epoxide; (2) amino groups and ternary N species as Lewis basic sites for activating CO2; (3) Br− anion as nucleophile to accelerate the opening of epoxy ring. Combining the high surface area (1146 m2/g) and numerous open pores, a high up to 97.3% of propylene carbonate yield and 100% of selectivity are achieved. Additionally, benefited from its good chemical stability, the catalyst maintains its high activity even after five successive runs. This work proposes a new strategy for constructing multifunctional catalyst for CO2 conversion by highlighting the synergistic effect enabled by one host.

Magnetically separable nano CuFe2O4: an efficient and reusable heterogeneous catalyst for the green synthesis of thiiranes from epoxides with thiourea

ABSTRACT The magnetically separable nano CuFe2O4 was prepared and used as an efficient heterogeneous catalyst for conversion of various epoxides to the corresponding thiiranes with thiourea in refluxing ethanol. The reactions were completed within 34−45 min to give thiiranes in 80−95% yields. The utilized nano CuFe2O4 can be reused for several times without losing its activity.

Ceria-Based Mixed Oxide Supported CuO: An Efficient Heterogeneous Catalyst for Conversion of Cellulose to Sorbitol

A series of CeO2-Al2O3, CeO2-TiO2, CeO2-ZrO2, and CeO2-SiO2 mixed-oxide supported copper catalysts were prepared by a modified deposition-precipitation method from ultra dilute aqueous solutions and were investigated for hydrogenolysis of cellulose in aqueous medium, in the presence of hydrogen to produce sorbitol as major product. Among all the catalysts tested in the present work, CuO/CeO2ZrO2 catalyst proved to be the most promising with high conversion (92%) and excellent selectivity (sorbitol 99.1%), at an intermediate reaction temperature of 245°C in a neutral aqueous solution without an aid of liquid phase acid. The catalyst was recyclable in repeated runs and no deactivation was observed even after five reaction cycles. CuO/CeO2-ZrO2 has been characterized by XRD, SEM, TPR and BET surface area techniques.

Functionalized dicyandiamide–formaldehyde polymers as efficient heterogeneous catalysts for conversion of CO2 into organic carbonates

The ABMDFP exhibited high activity on cycloaddition of CO2 and transesterification reaction of EC, which was also suitable for various substrates. A possible mechanism of ring-opening of epoxide and activation of CO2 was proposed.

Tin–Tungsten Mixed Oxide as Efficient Heterogeneous Catalyst for Conversion of Saccharides to Furan Derivatives

Abstract The Sn–W mixed oxide prepared by calcination of the Sn–W mixed hydroxide precursor with Sn/W molar ratio of 2:1 at 800 °C (Sn–W oxide) acts as an efficient heterogeneous catalyst for the synthesis of 5-hydroxymethylfurfural (HMF) and furfural from various hexoses (including polysaccharides) and pentoses, respectively.