One-step synthesis of a ZIF-8/90-based type I porous liquid.

A Type I porous liquid based on the mixed-linker zeolitic imidazolate framework, ZIF-8/90-PL, has been prepared by a one-step imine condensation reaction and characterized by X-ray diffraction, FT-IR spectroscopy, TGA and rheology analysis. This facile preparation strategy of a porous liquid has enormous industrial production and application potential, with over one kilogram of ZIF-8/90-PL being successfully prepared. ZIF-8/90-PL can be directly used as a liquid absorbent or be co-processed with alumina hollow fibers to form a composite membrane with improved selectivity in the context of CO2 separation from CH4 or N2. This simple synthesis method is expected to be extended to other metal-organic frameworks.

Novel Reactive Distillation Process for Cyclohexyl Acetate Production: Design, Optimization, and Control.

A side-reactor column (SRC) configuration, comprising a vacuum column coupled with atmospheric side reactors, is proposed to overcome the thermodynamic restriction in the esterification of cyclohexene with acetic acid to produce cyclohexyl acetate. Meantime, this configuration can avoid the utilization of the high-pressure steam and provide enough zone for catalyst loading. In order to obtain the minimum total annual cost (TAC), the process is optimized by a mixed-integer nonlinear programming optimization method based on the improved bat algorithm. The results indicate that the optimized SRC configuration saves about 44.81% of the TAC compared to the reactive distillation process. Based on the optimized SRC process, dynamic control is carried out. The dual-point temperature and temperature-composition control structures are proposed to reject throughput and feed composition disturbances. The dynamic performances demonstrate that the temperature-composition control structure is better in maintaining product purity.

Naphthenic Acids Removal from Model Transformer Oil by Diethylamine Modified Resins.

Resins have enormous potential in the removal of naphthenic acids (NAs) from transformer oil due to their rich porosity and high mechanical and diversified functionality, whereas their poor adsorption capacity limits application. In this work, the polystyrene-diethylamine resin (PS-DEA-x) was prepared by grafting diethylamine (DEA) onto chloromethylated polystyrene (PS-Cl) resin to efficiently adsorb cyclopentane carboxylic acid from transformer oil for the first time. The characterization analysis results indicated that amine contents were significantly enhanced with the increase in DEA. Particularly, resin with a molar ratio of 1:5 depending on chloromethyl to DEA (PS-DEA-5) exhibited the highest amine contents and efficient adsorption of cyclopentane carboxylic acid (static adsorption capacity up to 110.0 mg/g), which was about 5 times higher than that of the pristine PS-Cl. The thermodynamic and kinetic studies showed that the adsorption behaviors could be well fitted to the Langmuir isotherm equation and pseudo-second-order rate equation. Moreover, it was found that 1 g of the PS-DEA-5 can decontaminate about 760 mL transformer oil to meet reuse standards by a continuous stream, indicating its potential application in industry.

Type II porous ionic liquid based on metal-organic cages that enables L-tryptophan identification.

Porous liquids with chemical separation properties are quite well-studied in general, but there is only a handful of reports in the context of identification and separation of non-gaseous molecules. Herein, we report a Type II porous ionic liquid composed of coordination cages that exhibits exceptional selectivity towards L-tryptophan (L-Trp) over other aromatic amino acids. A previously known class of anionic organic-inorganic hybrid doughnut-like cage (HD) is dissolved in trihexyltetradecylphosphonium chloride (THTP_Cl). The resulting liquid, HD/THTP_Cl, is thereby composed of common components, facile to prepare, and exhibit room temperature fluidity. The permanent porosity is manifested by the high-pressure isotherm for CH4 and modeling studies. With evidence from time-dependent amino acid uptake, competitive extraction studies and molecular dynamic simulations, HD/THTP_Cl exhibit better selectivity towards L-Trp than other solid state sorbents, and we attribute it to not only the intrinsic porosity of HD but also the host-guest interactions between HD and L-Trp. Specifically, each HD unit is filled with nearly 5 L-Trp molecules, which is higher than the L-Trp occupation in the structure unit of other benchmark metal-organic frameworks.

La/LaF3 co-modified MIL-53(Cr) as an efficient adsorbent for the removal of tetracycline.

Chromium based metal-organic framework (MIL-53(Cr)) has enormous potential in the removal of organic contaminants from aqueous solutions due to its outstanding water stability, whereas its poor adsorption capacity limits the application. In this study, La/LaF3-MIL-53(Cr) was successfully synthesized by taking the advantages of La doping and LaF3 encapsulation with one-step hydrothermal method. Diverse analysis tools were utilized to verify that La not only existed in the framework, but also was loaded in the pores in the form of LaF3. The adsorption experiment results demonstrated that 0.3-La/LaF3-MIL-53(Cr) exhibited significantly improved adsorption capacity by four times compared with the pristine MIL-53(Cr) material. XPS and FTIR revealed that the affinity of La to tetracycline was significantly stronger than that of Cr and the excellent dispersion of LaF3 in the material may also be the cause of the increase in adsorption capacity. This study described a simple method to combine two different forms of modification and the modified material was potential for tetracycline adsorption.

Silica-confined Ru highly dispersed on ZrO2 with enhanced activity and thermal stability in dichloroethane combustion.

An efficient strategy (spontaneous deposition to enhance noble metal dispersity and core-shell confinement to inhibit noble metal sintering) is presented to synthesize highly active and thermally stable Ru/ZrO2@SiO2 catalysts for dichloroethane combustion.

Activated carbon prepared from catechol distillation residue for efficient adsorption of aromatic organic compounds from aqueous solution.

At present, activated carbon (AC) derived from industrial wastes has a great practical significance. In this work, residue activated carbon (RAC) was successfully synthesized from catechol distillation residue by a simple activation process based on two steps. The optimized RAC (RAC-800, activated at 800 °C) had high specific surface area (1800 m2/g) and large total pore volume (0.91 cm3/g). RAC-800 portrayed the evident increase of the graphitic structure and possessed abundant functional groups. Catechol (CC), phthalic acid (PA) and dimethyl phthalate (DMP) were chosen as typical pollutant to investigate the effect of different functional groups on adsorption aromatic compounds, and the equilibrium adsorption capacity of RAC-800 for CC, PA and DMP was 221.5, 365.0 and 449.9 mg/g, respectively. The adsorption behaviors were systematically studied by the combination of kinetic and thermodynamic model. The adsorption process was dominated by the π-π interaction, assisted by hydrogen bonding, hydrophobic and electrostatic interactions. In addition, regeneration study showed that the adsorption capacity can still remain over 88.5% after five cycles. In total, fine chemical distillation residues are promising to turn into the precursor of activated carbon, which has potential to be used as a good adsorbent for removal of aromatic compounds.

Simultaneous shaping and confinement of metal-organic polyhedra in alginate-SiO2 spheres.

The simultaneous shaping and confinement of Cu-based MOP in alginate-SiO2 spheres significantly enhance the mechanical strength and leaching resistance of Cu-MOP. The resulting MOP-alginate-SiO2 is shown through chemical fixation of CO2 to exhibit improved product yield over the parent Cu-MOP and Cu-alginate-SiO2.

High-efficiency treatment of benzaldehyde residue using two-stage fluidized-bed/fixed-bed catalytic system.

A novel two-stage fluidized-bed/fixed-bed catalytic system was developed for the treatment of benzaldehyde residue. The effects of reaction temperature, oxygen concentration, space velocity on the purification of benzaldehyde production residue were investigated. The effluent chemical oxygen demand (COD) was less than 70 mgO2/L and the COD removal efficiency was higher than 99.83% under our experimental condition (fluidized-bed and fixed-bed temperature of 300-400°C, the flow rate of residue of 10 mL/h and O2 excessive rate of 20). The volatile organic compounds (VOCs) of the outlet were not detected after the treatment. The high-efficiency performance of the process can last for at least 600 h in the stability experiment. It was also verified by gas chromatography-mass spectrometry (GC-MS) analysis that most organic pollutants in the residue were significantly removed after treatment. These results suggest that the two-stage fluidized-bed/fixed-bed catalytic system could be a promising technology for the dispose of chlorine-containing polymer organics in the chemical industry.

Modulating the basicity of Zn-MOF-74 via cation exchange with calcium ions.

The fine-tuning of metal-based molecular building blocks in Zn-MOF-74 through post-synthetic cation exchange with Ca2+ significantly enhances its basicity and corresponding catalytic performance. The resulting material, exemplified by Ca/Zn-MOF-74, is shown through Knoevenagel condensation to give an improved product yield over the parent Zn-MOF-74 and Ni/Zn-MOF-74.

A citric acid-assisted deposition strategy to synthesize mesoporous SiO2-confined highly dispersed LaMnO3 perovskite nanoparticles for n-butylamine catalytic oxidation.

Catalytic oxidation can efficiently eliminate nitrogen-containing volatile organic compounds (NVOCs) and suppress the generation of toxic NO x in order to avoid secondary pollution. In this study, mesoporous SiO2-confined LaMnO3 perovskite nanoparticles with high dispersion were successfully prepared by a citric acid-assisted deposition method (LMO/SiO2-SD) and tested for the oxidation of n-butylamine. The method utilized the synergistic effect of abundant active hydroxyl groups existing on the SiO2 gel surface and citric acid, rendering the metal ions more uniformly scattered on the SiO2 surface. Strikingly, the LMO/SiO2-SD sample exhibited the optimum catalytic performance (T 90 at 246 °C) and the highest N2 selectivity, which was mainly ascribed to its abundant surface acid sites, superior low-temperature reducibility and higher ratio of surface Mn4+ species. The apparent activation energy (E a) for n-butylamine oxidation over LMO/SiO2-SD sample was 29.0 kJ mol-1. Furthermore, the reaction mechanism of n-butylamine oxidation was investigated by in situ FITR and a reasonable reaction route for n-butylamine oxidation over the LMO/SiO2-SD sample was proposed.

Solvent-Assisted Stepwise Redox Approach To Generate Zeolite NaA-Supported K2O as Strong Base Catalyst for Michael Addition of Ethyl Acrylate with Ethanol.

Solid base catalysts featuring green, robustness, and high activity play an important role in the current fine-chemical and petrochemical industry. Normally, the generation of supported K2O by thermal decomposition of KNO3 requires high temperature, and this process can sometimes destroy the structure of supporting materials. We herein report a solvent-assisted stepwise redox (SASR) approach to generate zeolite NaA-supported K2O, which we call K2O/NaA, that function as the solid base catalyst for Michael addition reaction between ethanol and ethyl acrylate. The solvent-assisted redox decomposition process of KNO3 at elevated temperature was investigated by thermogravimetry-mass spectrometry. It reveals that after reducing a minor amount of KNO3 at 400 °C, the organic solvent decomposes to form carbon, which promotes the reduction of KNO3 to generate strong basicity on the zeolite NaA at 600 °C. The resulting material, K2O/NaA-S, exhibits improved catalytic activity in Michael addition reaction over other benchmark base catalysts that have been used in this reaction. This catalyst is durable for at least four catalytic cycles without apparent loss in activity. K2O/NaA-S exhibits larger reaction rate constant yet lower activation energy than K2O/NaA prepared by thermal decomposition method. The SASR approach described in this paper represents a new blueprint for the generation of the supported alkali oxide as the solid base catalyst.