UiO-66 was successfully synthesized in the absence of any amide solvents and hydrochloric acid by using the dry-gel conversion (DGC) method for the first time. The prepared UiO-66 samples (denoted as UiO-66-DGC) were characterized by XRD, SEM, TGA, CO2 adsorption, NH3-TPD, and N2 adsorption. The results showed that the UiO-66-DGC-E sample synthesized by using ethanol as solvent has similar crystallinity and morphology to the UiO-66 sample prepared by the conventional solvothermal method (denoted as UiO-66-S). However, it has more linker deficiencies, indicating the presence of more defects exposed in Zr clusters. As a result, the prepared UiO-66-DGC-E sample exhibited high catalytic activity and reusability in esterification. This preparation method provides a new alternative method for the efficient and eco-friendly synthesis of metal–organic frameworks (MOFs) and modification of their properties.

The SBA-16 obtained by different routes of elimination of organic templates were used as the hosts for encapsulation of chiral Ru complex (1S,2S)-DPEN-RuCl2(TPP)2 (1) (DPEN = 1,2-diphenylethylene-diamine, TPP = triphenyl phosphine). The methods for removing templates had distinct effects on the amount of residual template in SBA-16, which made the SBA-16 with different surface and structure properties. 1 encapsulated in SBA-16 extracted with the mixture of pyridine and ethanol showed higher activity and enantioselectivity for acetophenone asymmetric hydrogenation.

Controlled synthesis of porous metal oxides with desired morphology has been motivating scientists to explore and develop new preparation methodologies. Among them, thermal decomposition of metal–organic frameworks (MOFs) has been employed for the fabrication of several metal oxides. In this work, this strategy is employed to prepare mesoporous and tetragonal zirconia (t-ZrO2) from a metal–organic framework (UiO-66), acting as both a morphological template and a zirconium source. This process avoids the use and removal of an extra template as well as the addition of stabilizers for t-ZrO2. After thermal decomposition at 500 °C, t-ZrO2 inherited an octahedral morphology from the pristine precursor and possessed small nanoparticles with an average size of 3.1 nm. The derived t-ZrO2 had a large surface area of 174 m2 g−1 and a pore diameter of 5–8 nm. The formation mechanism of t-ZrO2 was also discussed. This simple and potentially universal strategy can be used to fabricate porous metal oxides with desired shape for many applications.

•A novel strategy for preparing metal complex functionalized LDH was proposed.•The immobilized metal complexes can be neutral or positive.•The hybrids with high metal complex loading can be prepared by this strategy.In order to immobilize neutral or positive metal complexes on layered double hydroxides (LDHs) and increase the amount of immobilized metal complexes, a novel strategy for the preparation of metal complex functionalized LDHs is proposed. This strategy involves exfoliating glycine-intercalated MgAl LDH in formamide under an ultrasound treatment, and then grafting silylated metal complexes on MgAl LDH nanosheets, as exemplified by immobilization of Co Schiff-base on MgAl LDHs. The prepared hybrids were characterized by XRD, AFM, FT-IR, TG, N2 adsorption–desorption and ICP techniques and their catalytic performances were investigated in H2O2 decomposition and styrene epoxidation with O2. The results showed that the hybrid prepared by this strategy had higher Co Schiff-base loading than the sample prepared by directly grafting silylated Co Schiff-base on glycine-intercalated MgAl LDHs due to the more accessible grafting sites on the exfoliated MgAl LDH nanosheets. Additionally, it was found that the grafted complexes could effectively impede the restack of LDH nanosheets after removal of the solvent. Thus, the prepared hybrid exhibited higher surface area and more accessible active centers, which made the prepared hybrid exhibit high catalytic activity in H2O2 decomposition and styrene epoxidation with O2. This work gives us a new way to prepare LDH hybrids functionalized with various metal complexes.

•Chloromethylation was performed on phenylene sites in the framework of PMOs.•Amination of PMOs was achieved via reacting –C4H3CH2Cl– with piperazine.•RuSalen could be covalently attached on aminated PMOs.•RuSalen on aminated PMOs showed higher activity in cyclohexene oxidation with H2O2.•RuSalen on aminated PMOs were more stable than that on aminated SBA-15.A new approach was employed to prepare metal complex-functionalized periodic mesoporous silica. This approach mainly involves the following three steps, that is, chloromethylation of –C6H4– sites in the framework of PMOs into active –C6H3CH2Cl–, amination of PMOs via reacting –C6H3CH2Cl– with piperazine and covalent attachment of RuSalen by refluxing the aminated PMOs in RuSalen ethanol solution. The obtained hybrid material was characterized with XRD, N2 sorption, FTIR, diffuse reflectance UV–vis spectroscopy, TEM and 13C MAS NMR techniques. It shows higher activity and stability in the oxidation of cyclohexene with H2O2 than the corresponding RuSalen functionalized SBA-15 prepared by the similar method except that the introduction of active –C3H6Cl was achieved by grafting 3-chloropropyltriethoxysilane on SBA-15.

A series of MgAl hydrotalcites (HTs) was synthesized in the presence of glucose and used as the precursors for the preparation of MgAl mixed oxides. The as-synthesized MgAl HTs and their corresponding MgAl mixed oxides were characterized by XRD, TG, SEM, N2-adsorption/desorption, FTIR, Raman spectroscopy, ICP and CO2 TPD. The results show that MgAl mixed oxides derived from MgAl HTs prepared in the different synthesis systems have different textural characteristics, basic properties, and catalytic performances. The glucose in MgAl HT synthesis system was transformed into amorphous carbon during the process of MgAl HT crystallization, and the in-situ formed highly dispersed carbon in the as-synthesized MgAl HT matrices can act as a mesoporous template. MgAl mixed oxides derived from MgAl HTs prepared in the presence of glucose have higher surface areas, more uniform mesoporous pores, stronger basic sites as well as higher activities in transesterification of tributyrin with methanol than that from MgAl HT prepared in the absence of glucose.Highlights► A series of hydrotalcites (HTs-x) were synthesized in the presence of glucose. ► The calcined HTs-x showed stronger basic sites than calcined HTs. ► The calcined HTs-x showed uniform mesoporous. ► The calcined HTs-x exhibited high catalytic activity in transesterification.

Liquid-phase epoxidation of styrene with atmospheric O2 was conducted over CoAPO-5 molecular sieves. The catalytic performance of CoAPO-5 can be significantly improved by alkali metal salt impregnated on it, and styrene conversion and selectivity to styrene oxide reached 85% and 69% respectively when CsCl was impregnated on it. The catalyst was recyclable and exhibited similar catalytic activity and selectivity even after three catalytic reaction cycles.

A series of CoOx/SiO2 catalysts has been prepared by the sol–gel method and characterized with XRD, N2 adsorption/desorption, diffuse reflectance UV–vis spectroscopy, Raman spectroscopy as well as TPR techniques. This type of material is highly active and selective for the epoxidation of cyclooctene with atmospheric molecular oxygen. Although all the catalysts attained at different pH values are amorphous, their catalytic activities are remarkably different because the pH values influence not only the coordination state of Co species but also the textural structures of the prepared catalysts, in which CoOx/SiO2 obtained at pH below 5 is highly active and selective for the epoxidation of cyclooctene with atmospheric O2. The prepared CoOx/SiO2 catalysts are highly stable and can be recycled at least four times without significant loss of activity and selectivity.

Zirconium-based MOFs of the UiO family have attracted considerable attention due to their high thermal, chemical and mechanical stability. With the aim of further exploring the applications of zirconium-based UiO-66 in acid-catalyzed reactions and elucidating the effects of the defects in UiO-66 materials on their catalytic performances, in this work, a series of zirconium-containing UiO-66 samples were synthesized by varying the synthesis temperatures and BDC/Zr (terephthalic acid/ZrCl4) ratios in the synthesis system. The synthesized UiO-66 samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), thermogravimetrical analysis (TGA), temperature-programmed desorption of NH3 (NH3-TPD). Their catalytic performances were investigated in transesterification of tributyrin and soybean oil with methanol. The results showed that UiO-66 samples with different amounts of defects could be successfully prepared by varying the synthesis temperatures and/or the BDC/Zr ratios used in the synthesis system. The catalytic activities of the UiO-66 materials greatly depended on their linker defects and enhanced with the increase of the defect amount. The UiO-66 was an efficient catalyst for transesterification of tributyrin and soybean oil with methanol under mild reaction conditions and its catalytic activity was comparable to other solid acid catalysts reported in the literatures. The UiO-66 catalyst was relatively stable and could be reused.Download high-res image (124KB)Download full-size imageUiO-66 is an efficient and reused catalyst for transesterification of tributyrin and soybean oil with methanol.