Enhancing the activity,selectivity,and recyclability of Rh/PPh_(3) system‐catalyzed hydroformylation reactions through the development of a PPh_(3)‐derived quasi‐porous organic cage as a ligand

In contrast to heterogeneous network frameworks(e.g.,covalent organic frameworks and metal‐organic frameworks)and porous organic polymers,porous organic cages(POCs)are soluble molecules in common organic solvents that provide significant potential for homogeneous catalysis.Herein,we report a triphenylphosphine‐derived quasi‐porous organic cage(denoted as POC‐DICP)as an efficient organic molecular cage ligand for Rh/PPh_(3) system‐catalyzed homogeneous hydroformylation reactions.POC‐DICP not only displays enhanced hydroformylation selectivity(aldehyde selectivity as high as 97%and a linear‐to‐branch ratio as high as 1.89)but can also be recovered and reused via a simple precipitation method in homogeneous reaction systems.We speculate that the reason for the high activity and good selectivity is the favorable geometry(cone angle=123.88°)and electronic effect(P site is relatively electron‐deficient)of POC‐DICP,which were also demonstrated by density functional theory calculations and X‐ray absorption fine‐structure characterization.

Sequential Extraction of Aluminum and Iron from Acidic Soils by Chemical Selective Dissolution Methods

Potassium chloride, Na-pyrophosphate, CuCl2, NH4-oxalate, dithionite-citrate-bicarbonate (DCB) and Na-citrate solutions were employed to extract aluminum (Al) and iron (Fe) sequentially and separately from 15 acidic soils located at the Mangshan Mountains, Hunan Province, China. Many evidences showed that separate pyrophosphate extracted mainly KCI-extractable Al, organo-Al complexes and some inorganic Al compounds, whereas separate CuCl2 extracted KCl-extractable Al and some organo-Al complexes. CuCl2 extracted much less amounts of Al than pyrophosphate did from the soils. Separate oxalate did not extract all KCl-Pyrophosphate- CuCl2 -oxalate sequentially extractable Al and Fe. Also, separate DCB did not extract all KCl- pyrophosphate- CuCl2 -oxalate- DCB sequentially extractable Al. The forms of Al extracted by oxalate and DCB from the soils were majorly noncrystalline. The interlayered materials of 1.4-nm intergrade minerals of the soils were attributed mainly to hydroxy Al polymers.

Fabrication of Through Micro-hole Arrays in Silicon Using Femtosecond Laser Irradiation and Selective Chemical Etching

We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.

A new horizontal in C1 chemistry: Highly selective conversion of syngas to light olefins by a novel OX-ZEO process

The most challenging goal of C1 chemistry is the control of C–C coupling to produce chemicals or fuels from C1 feedstocks,in particular syngas（H2/CO）,which can be derived from various carbon resources such as coal,natural gas or shale gas,and biomass.

Application of Air Separation Unit in SINOPEC's Coal Chemical Business

With the rapid growth of coal chemical industry in China, the selection and application of Air Separation Unit(ASU) became very important. As the core unit in coal chemical industry, ASU will greatly impact the engineering construction and operation/production of coal chemical business. In this paper, major suppliers of ASU at home and abroad were reviewed, and the major supplying status of ASU in China was introduced. The ASUs in operation of SINOPEC were listed and discussed. On this basis, some suggestions of ASU selection strategies were provided on localization, standardization and operation methods.

A selective optical chemical sensor for the determination of iodine based on fluorescence quenching of LiTOE

An optical chemical sensor has been developed for the determination of iodine based on the reversible fluorescence quenching of 2, 2, 7, 7, 12, 12, 17, 17-octamethyl-21, 22, 23, 24-tetraoxaquaterene-Li （LiTOE） immobilized in a plasticized poly（vinyl chloride） （PVC） membrane. The optimum membrane of the sensor consists of 100 mg of PVC, 200 mg of bis （2-ethytbexyl） sebacate （BOS） and 3.0 mg of LiTOE. The maximum response of the optode membrane for iodine is obtained in Tris-HCl buffer solutlon （pH 8.0）. With the optimum conditions described, the proposed sensor responds linearly in the measuring range of 3.90×10^-2 to 3.90×10^-4 mol/L, and has a detection limit of 6.0×10^-8 mol/L. The response time of the sensor is less than I rain. In addition to high reproducibility and reversibility of the fluorescence signal, the sensor also exhibits good selectivity. It is not interfered by some common anions and cations. It is applied for the determination of iodine in table salt samples. The results agree with those obtained by another method.

Erosion of a Polyimide Material Exposed to Simulated Atomic Oxygen Environment

Oxygen plasma source generated by thermal cathode filament discharge has been used to study the erosion process of polyim- ide （PI） materials in atomic oxygen （AO） environment, and their mass loss, surface morphology and surface chemical composi- tions have been examined by scanning electron microscope （SEM） and X-ray photoelectron spectroscopy （XPS） after exposure to incremental AO flux. The data indicate that the physical adsorption of AO at the samples＇ surface results in the increase of oxygen concentration when polyimide is exposed to AO flux. Then selective chemical reactions of groups of polyimide materials with AO yield volatile organic compounds, sample mass loss is on linear increase and carpet-like surface morphology forms. In the initial exposure to AO, the reaction occurs mainly between AO and carbon in specific location of aromatic ring, then the re- action rate of C=O groups gradually increases. After AO exposure, the oxygen concentration increases while nitrogen and carbon concentration decreases. Reaction rate of groups containing nitrogen is slower compared with carbon and oxygen.