The effect of monocarboxylic acids on synthesizing NH2-MIL-125 is systematically studied for the first time in this work, and the fantastic results are discussed in detail. We found that a small molecular acid (acetic acid, thioglycolic acid) mostly affects the morphology changes of NH2-MIL-125, while the pseudolinker acid (p-toluylic acid, benzoic acid) has a significantly impact on the crystal size on account of the nucleation and the crystal growth rates. Ar sorption measurement and transmission electron microscopy characterization show that samples synthesized with pseudolinker acid as additives have a hierarchical structure owing to the internal defects or caves formed in the crystal. These samples also show an excellent performance for the removal of organic pollutants by the combined effects of adsorption and photodegradation.

A commercial β zeolite was modified with dilute oxalic acid solutions, and evaluated in the catalytic dehydration of 2-(4′-ethylbenzoyl)–benzoic acid (BEA) to produce 2-ethylanthraquinone (2-EAQ). The modified zeolite samples were characterized by X-ray diffraction, Ar-physisorption, X-ray fluorescence spectroscopy, Fourier transform infrared spectroscopy, 27Al MAS NMR and ammonia temperature-programmed desorption. The results show that the modified samples maintain the BEA topology and microporous textural properties. However, dealumination, caused by the modification, leads to dramatic variations in acid properties, including the amount of acid sites, ratio of strong to weak acid sites, and the ratio of Brönsted to Lewis acid sites. The variations in acidity enhance the catalytic performance of BEA dehydration to produce 2-EAQ. The catalytic selectivity was tripled, and the activity increased significantly.

ZSM-5 that uses TPAOH as a template has an Al-rich exterior and defective Si-rich interior; thus, a simple base leaching selectively removed the Si-rich interior while the Al-rich exterior was protected. This catalyst showed no change in stability comparing with parent ZSM-5 during the MTP reaction that was attributed to the enclosed hollow structure and richly acidic outer shell. A preliminary fluorination, however, both removed defective Si-sites and caused distortion in tetrahedral aluminum that made the outer shell susceptible to alkaline treatment. These distorted tetrahedral Al were mostly leached out by NaOH in 1 min. Furthermore, aluminum in the filtrate was slowly redeposited onto the zeolite, serving as external pore-directing agents to control silicon dissolution from the Si-rich interior. This dealumination–realumination alkaline treatment process led to a higher solid yield and a uniform opened-mesopore structure with mesopores around 13 nm in diameter. This material was characterized by SEM, TEM, N2 adsorption, and mercury porosimetry. In addition, NH3-TPD, OH-IR, 27Al MAS NMR, and 1H MAS NMR results demonstrated that the reinserted Al were unlike the framework Al, contributing less to acidity. The dealumination–realumination process, therefore, was also capable of tuning the acidity of the mesoporous ZSM-5. This mesoporous catalyst exhibited a longer lifetime and a higher propylene selectivity than other catalysts with an enclosed mesopore structure.Keywords: Al-zoned ZSM-5; dealumination−realumination process; distorted tetrahedral Al; enclosed hollow structure; interconnected mesopore structure; MTP; reinserted Al;

A postsynthetic modification method was used to prepare thiol-functionalized metal–organic frameworks (MOFs) by the amidation of mercaptoacetic acid with the amine group, which is present in the frameworks of NH2-MIL-53(Al). By doing this, the thiol group has been successfully grafted on the MOF, which perfectly combined the highly developed pore structures of the MOF with the strong coordination ability of the thiol group. The resulting thiol-functionalized MIL-53(Al) showed a significantly high adsorption capacity for heavy metal ions like Ag+ (182.8 mg g−1). Even more importantly, these grafted thiol groups can be used as anchoring groups for stabilizing metal nanoparticles (NPs) with controllable sizes. Taking silver as an example, monodispersed Ag NPs encapsulated in the cages of MIL-53(Al) have been prepared by using a two-step procedure. In addition, the particle size of the Ag NPs was adjustable to some extent by controlling the initial loading amount. The average size of the smallest Ag NPs is 3.9 ± 0.9 nm, which is hard to obtain for Ag NPs because of their strong tendency to aggregate.

We present here a simple solvothermal method to fabricate metal–organic framework NH2-MIL-53(Al) crystals with controllable size and morphology just by altering the ratio of water in the DMF–water mixed solvent system without the addition of any surfactants or capping agents. With increasing the volume ratio of water in the mixed solvents, a series of NH2-MIL-53(Al) crystals with different sizes and morphologies were synthesized. The average size of the smallest crystal is 76 ± 20 nm, which provides us a simple and environmentally friendly way to prepare nanoscale MOFs. The largest BET surface area of these samples is 1882 m2 g−1 that is mainly contributed by its micropore surface area, and its corresponding micropore volume is 0.83 cm3 g−1, which have greatly extended its application in the fields of gas adsorption and postsynthetic modification. All these samples were characterized by SEM, XRD, N2 adsorption/desorption, TGA and FT-IR. Then a mechanism for the impact of the water ratio on the crystal size and morphology is presented and discussed.

Sulfonated sucrose-derived carbon, glucose-derived carbon, and nut shell activated carbon (NSAC) catalysts were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS spectra showed that −SO3H groups could be introduced into the carbon precursors after the sulfonation treatment. Higher concentration of −SO3H groups in the sulfonated sucrose-carbon and glucose-carbon most likely accounts for their higher activities compared to sulfonated NSAC. Hydrolysis of microcrystalline cellulose was examined in a common ionic liquid, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), with the sulfonated carbon catalysts. Maximum yields of glucose (59%) and total products (80%, defined as the sum of glucose, cellobiose, and 5-hydroxymethylfurfural) could be obtained with sulfonated sucrose-carbon at 120 °C for 4 h. With a regeneration procedure, the catalyst could be reused.

Titanium silicalite-1 (TS-1) with little extraframework Ti was hydrothermally synthesized in a tetrapropylammonium hydroxide system using starch as the additive. The influences of the amount of starch added on the coordination states of titanium ions and the functional mechanism of starch were studied by various characterization means. The addition of starch slowed the crystallization rate of TS-1 so that the insertion rate of titanium to the framework matched well with that of silicon. Therefore, the generation of extraframework Ti, including the anatase TiO2 and octahedrally coordinated titanium, was eliminated. The catalytic performances of the TS-1 samples were evaluated in the epoxidation of 1-butene to produce butene oxide. The catalytic activity of TS-1 was improved significantly due to the increasing amount of framework Ti.Topics: Catalysts; Crystal structure; Reaction kinetics; Reaction kinetics; Redox reaction; Redox reaction; Spectra;

We present here a simple solvothermal method to fabricate metal–organic framework NH2-MIL-53(Al) crystals with controllable size and morphology just by altering the ratio of water in the DMF–water mixed solvent system without the addition of any surfactants or capping agents. With increasing the volume ratio of water in the mixed solvents, a series of NH2-MIL-53(Al) crystals with different sizes and morphologies were synthesized. The average size of the smallest crystal is 76 ± 20 nm, which provides us a simple and environmentally friendly way to prepare nanoscale MOFs. The largest BET surface area of these samples is 1882 m2 g−1 that is mainly contributed by its micropore surface area, and its corresponding micropore volume is 0.83 cm3 g−1, which have greatly extended its application in the fields of gas adsorption and postsynthetic modification. All these samples were characterized by SEM, XRD, N2 adsorption/desorption, TGA and FT-IR. Then a mechanism for the impact of the water ratio on the crystal size and morphology is presented and discussed.