Efficient conversion of fructose to 5-hydroxymethylfurfural over sulfated porous carbon catalyst

Sulfated porous carbon (PC-SO3H) catalyst was successfully synthesized from one-pot treatment of porous polydivinylbenzene in H2SO4 at 250 C, which exhibited very good catalytic performances in the production of 5-hydroxymethylfurfural from fructose.     

Selective conversion of fructose into 5-ethoxymethylfurfural over green catalyst

Research on Chemical Intermediates - In this study, selective formation of 5-ethoxymethylfurfural (EMF) from one-pot conversion of fructose in a co-solvent of ethanol with tetrahydrofuran over...     

Allylic oxdation of alkenes with molecular oxygen catalyzed by porous coordination polymers Fe-MIL-101 and Cr-MIL-101

The catalytic performances of Cr-MIL-101 and Fe-MIL-101 porous coordination polymers have been investigated in the allylic oxidation of alkenes, including natural terpenes, with molecular oxygen (1 atm) under mild solvent-free conditions. Both catalysts remain stable under optimal conditions (40°C for Fe-MIL-101 and 60°C for Cr-MIL-101) and can be recycled, at least, four times without loss of the catalytic properties. Fe-MIL-101 favours the formation of unsaturated alcohols, while Cr-MIL-101 mediates the formation of unsaturated ketones. The oxidation process involves the formation of alkene hydroperoxide via conventional radical chain process and its further transformations over the MIL-101 catalysts. The mechanism of the hydroperoxide transformation strongly depends on the metal nature.     

Cyclohexane selective oxidation over metal-organic frameworks of MIL-101 family: superior catalytic activity and selectivity

Mesoporous metal-organic frameworks Cr- and Fe-MIL-101 are highly efficient, true heterogeneous and recyclable catalysts for solvent-free selective oxidation of cyclohexane with molecular oxygen and/or tert-butyl hydroperoxide under mild conditions.     

Efficient thermal conversion of polyyne-type conjugated polymers to nano-structured porous carbon materials

Summary Some aromatic based conjugated polymers having carbon-carbon triple bonds moiety were synthesized and carbonized. The polymers were efficiently carbonized by heating up to 900°C under an argon atmosphere, affording porous carbons in high yields. The polymer characteristics were appropriate to form nano-structured carbons in the pyrolytic carbonization process. The carbon materials were consisted of 2-4 nm sized graphitic crystallites and had slit-shaped micropores with ca. 0.7 nm pore width. Structural defects in the pre-carbon materials caused generation of mesopores with ca. 4 nm pore width after carbonization.     

Selective transformation of carbohydrates to 5-ethoxymethylfurfural over tungstophosphoric acid supported on activated carbon derived from orange peel

A series of tungstophosphoric acid supported on activated carbon derived from left-over orange-peel catalysts (TPA/OAC) have been prepared. These catalysts were examined for one-pot catalytic transformation of fructose/glucose to 5-ethoxymethylfurfural. Physico-chemical properties of the catalytic materials were executed by using various characterization methods. Spectroscopic analysis results propose that TPA was finely distributed on the high surface area carbon support with persistent Keggin ion structure. The EMF yield is depended on the content of active component TPA on support and also on the reaction conditions. The catalyst with 25 wt% TPA on OAC presented highest activity towards EMF synthesis from fructose. Although, the catalyst 25 wt% TPA/OAC showed low activity towards EMF synthesis from glucose, higher yields of ethyl glucopyranoside could be formed from glucose in EtOH. Activated carbon was synthesized by carbonization of orange peel treated with H₃PO₄, which was used as a good support for HPAs. The catalysts are quite stable and recyclable for the dehydrative alkylation of fructose.     

Impact of metalloporphyrin-based porous coordination polymers on catalytic activities for the oxidation of alkylbenzene

Seven metalloporphyrin-based porous coordination polymers: Fe^ш (TZP)Poly ( CP1 ), Co^II (TZP)Poly ( CP2 ), Ni^II (TZP)Poly ( CP3 ), Cu^II (TZP)Poly ( CP4 ), Zn^II (TZP)Poly ( CP5 ), Mn^II (TZP)Poly ( CP6 ), Pb^II (TZP)Poly ( CP7 ) (TZP = 5,10,15,20- tetrakis[4-(2,3,4,5-tetrazolylphenyl)] porphyrin) were prepared and characterized. CP1−CP7 are amorphous aggregation supported with lower crystallinity by scanning electron microscopy, Brunauer−Emmett−Teller and powder X-ray diffraction. These coordination polymers exhibit effective dye scavenging and catalytic activities toward the oxidation of alkylbenzene to ketones and can be reused by filtration with a slight decreasing of catalytic activities. Metal atoms metalloporphyrin polymers have a great influence on the catalytic activities of metalloporphyrin polymers.     

MIL-101限域Au纳米颗粒催化对硝基苯酚加氢反应

利用MIL-101有序纳米孔道的限域能力,制备出一系列尺寸较小且分散度均匀的Au纳米颗粒Au@MIL-101催化剂,通过X射线衍射、高分辨透射电子显微镜、物理吸附仪和原子发射光谱仪对该催化剂进行了表征.该催化剂在温和的反应条件下对对硝基苯酚加氢反应表现出良好的催化活性.     

A 3D MIL-101@rGO composite as catalyst for efficient conversion of straw cellulose into valuable organic acid

Efficient conversion of straw cellulose to chemicals or fuels is an attracting topic today for the utilization of biomass to substitute for fossil resources. The development of catalysts is of vital importance.In this work, a composite catalyst metal-organic frameworks(MOFs) immobilized on three-dimensional reduced graphene oxide(3D-r GO) were synthesized by in situ growth of the MIL-101(Cr) within the 3Dr GO matrix. The supporting of 3D-r GO guaranteed the dispersion and acid site density of MI...     

Radical polymerisation of styrene in porous coordination polymers

The first radical polymerisation of styrene in porous coordination polymers has been carried out, providing stable propagating radicals (living radicals), and a specific space effect of the host frameworks on the monomer reactivity is demonstrated.     

Magnetically-recoverable carbonaceous material: An efficient catalyst for the synthesis of 5-hydroxymethylfurfural and 5-ethoxymethylfurfural from carbohydrates

A novel, magnetically recoverable carbonaceous solid acid Fe₃O₄@C-SO₃H catalyst for the conversion of carbohydrates to 5-ethoxymethylfurfural (EMF) was developed. The effect of the DMSO fraction in the ethanol-DMSO binary solvent on the distribution of the reaction products was investigated. The catalyst showed an excellent activity in the synthesis of EMF from fructose and 5-hydroxymethylfurfural (HMF). 5- Ethoxymethylfurfural was also obtained with a high yield of 64.2% in an ethanol–DMSO solvent system via one-step conversion of fructose. After reaction, the catalyst could be recovered by exposure of the reaction mixture to external magnetic field and reused several times without a loss of catalytic activity.     

Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101: Insight into chromium species on activity and selectivity

Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCr Al-I1 with largest specific surface area of 198 m2 g-1prepared with aluminium isopropoxide(Al(i-OC3H7)3) by ultrasonic impregnation method. However, the catalyst KCr Al-I2 synthesized by stirring impregnation possessed crystalline α-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich Crx Al2-xO3 solid solutions, designated as Cr Al-I and Cr Al-II phase, were formed over the catalysts KCr Al-I3(prepared by Al(i-OC3H7)3with nitric acid regulation), KCr Al-C4(prepared by aluminium chloride hexahydrate) and KCr Al-N5(prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCr Al-I1 exhibited the high isobutane conversion due to its highly dispersed chromium species. However, KCr Al-I3, KCr Al-C4 and KCr Al-N5 showed the higher isobutene selectivity(95.2%-96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.     

Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101:Insight into chromium species on activity and selectivity

Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCrAI-I1 with largest specific surface area of 198 m2-g-1 prepared with aluminium isopropoxide （Al（i-OC3HT）3） by ultrasonic im- pregnation method. However, the catalyst KCrAI-I2 synthesized by stirring impregnation possessed crystalline a-Cr203 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich CrzA12_zO3 solid solutions, designated as CrAI-I and CrAI-II phase, were formed over the catalysts KCrAI-I3 （prepared by Al（i-OC3HT）3 with nitric acid regulation）, KCrA1-C4 （prepared by aluminium chloride hexahydrate） and KCrA1-N5 （prepared by aluminium nitrate nonahydrate）. Catalytic evaluation results revealed that KCrAI-I1 exhibited the high isobutane con- version due to its highly dispersed chromium species. However, KCrAI-I3, KCrA1-C4 and KCrA1-N5 showed the higher isobutene selectivity （95.2%-96.4%） on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.     

Wide control of proton conductivity in porous coordination polymers

The proton conductivities of the porous coordination polymers M(OH)(bdc-R) [H(2)bdc = 1,4-benzenedicarboxylic acid; M = Al, Fe; R = H, NH(2), OH, (COOH)(2)] were investigated under humid conditions. Good correlations among pK(a), proton conductivity, and activation energy were observed. Fe(OH)(bdc-(COOH)(2)), having carboxy group and the lowest pK(a), showed the highest proton conductivity and the lowest activation energy in this system. This is the first example in which proton conductivity has been widely controlled by substitution of ligand functional groups in an isostructural series.     

Azo-bridged hydroxyl-rich porous pillar[5]arene polymers for efficient carbon dioxide conversion

Two new azo-bridged hydroxyl-rich porous organic polymers (POPs), named PPDA-P5 and TB-P5, were designed and successfully fabricated via azo-coupling reaction with per-hydroxylated pillar[5]arene macrocycle as the core and p-phenylenediamine and Troger's base (TB) diamine as the linker, respectively. Owing to the abundant nitrogen and hydroxyl groups, both polymers exhibited excellent interaction affinity toward carbon dioxide (CO₂) and then were applied as efficient heterogeneous catalysts for the transformation of CO₂ to cyclic carbonates with high yield, even under mild conditions. Interestingly, TB-P5 exhibited superior catalytic performance toward PPDA-P5, indicating TB's positive role as an organic base. This design strategy and results provided new insight into the development of macrocycle-based POPs in the field of heterogeneous catalysis.     

Dynamic porous properties of coordination polymers inspired by hydrogen bonds

In a decade, many porous coordination polymers have been synthesized, providing a variety of properties ranging from storage, separation, exchange of guests in their cavities, magnetism, conductivity and catalysis by their frameworks. In this tutorial review, we focus on the hydrogen bonding type arrangements for dynamic porous coordination polymers exhibiting elastic guest accommodations, in contrast to rigid three-dimensional (3-D) frameworks. Such dynamic porous properties induce highly-selective guest accommodation and magnetic modulation, and could now be considered a new class of practical materials.