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Biomass-based polymers and their property regulation using functional materials have attracted much interest. In this work, ricinoleic acid-derived cyclic carbonate was prepared and applied to the synthesis of nonisocyanate polyurethane (NIPU) with aliphatic diamine, in which octa(aminopropyl) polyhedral oligomeric silsesquioxane (OAP-POSS) was incorporated as polyamine to partially or totally substitutes for the diamine to introduce POSS units into the polymer thus regulating the properties of the resultant material. In the curing process, Fourier transform infrared spectroscopy (FT-IR) was used to track the reaction and curing at 50[degrees]C for 12 h was found to be sufficient for the polymerization. A series of POSS modified NIPUs were obtained by altering the molar fraction of OAP-POSS in total amine components and the material with the highest thermal stability, shore hardness and water resistance was accessed with 100% substitution of OAP-POSS for diamine. KEYWORDS biomass utilization, nonisocyanate polyurethanes, POSS modification, ricinoleic acid, 1 | INTRODUCTION The excessive consumption of fossil fuels has led to massive carbon dioxide emissions, resulting in global warming and consequent detrimental environmental impacts. [1] Moreover, fossil resources are [...]

A Cu/Co tandem catalysis protocol was developed to conduct the hydroformylation of olefins using CO2/H2 and PMHS (polymethylhydrosiloxane) as a readily available and environmentally friendly hydride source. This methodology was performed via a two‐step approach consisting of the copper‐catalyzed reduction of CO2 by hydrosilane and subsequent cobalt‐promoted hydroformylation with H2 and the in situ formed CO. The optimized triphos oxide ligand, which presumably facilitates the migratory insertion of CO gives moderate to excellent yields for both terminal and internal alkenes. This earth‐abundant metal catalysis provides a reliable and efficient way to afford useful aldehydes in industry using silicon by‐product PMHS as hydrogen source and renewable CO2 as carbonyl source. [ABSTRACT FROM AUTHOR]

Designing earth‐abundant metal complexes as efficient molecular photocatalysts for visible light‐driven CO2 reduction is a key challenge in artificial photosynthesis. Here, we demonstrated the first example of a mononuclear iron pyridine‐thiolate complex that functions both as a photosensitizer and catalyst for CO2 reduction. This single‐component bifunctional molecular photocatalyst efficiently reduced CO2 to formate and CO with a total turnover number (TON) of 46 and turnover frequency (TOF) of 11.5 h−1 in 4 h under visible light irradiation. Notably, the quantum yield was determined to be 8.4 % for the generation of formate and CO at 400 nm. Quenching experiments indicate that high photocatalytic activity is mainly attributed to the rapid intramolecular quenching protocol. The mechanism investigation by DFT calculation and electrochemical studies revealed that the protonation of Febpy(pyS)2 is indispensable step for photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

A series of KF/Mg‐Fe oxides were fabricated via the solid‐state reaction between KF and Mg‐Fe oxides. Especially, when 20 wt % KF was supported on the Mg‐Fe bi‐metal oxides and calcined at 400–600 °C, the solid material with more basic sites than the support itself was obtained. When applied as catalyst to dimethyl carbonate (DMC) synthesis through transesterification of ethylene carbonate (EC) and methanol, this material can afforded up to 88 % yield and 97 % selectivity toward DMC in 2 h under reflux conditions with the molar ratio of methanol to ethylene carbonate set at 8. It is worth noting that the catalyst was easily separated and reused, retaining at least 89 % catalytic activity during the first four recycles. Although an attenuated activity was still observed due to the inevitable filtration loss and dissolution, this solid base can still provide clues to the development recyclable catalyst in green synthesis of DMC. [ABSTRACT FROM AUTHOR]

Capturing CO2 and subsequently converting into valuable chemicals has attracted extensive attention. Herein, a series of biomass‐based N‐rich porous carbon materials with high specific surface area and pore volume were prepared using biomass waste soybean dregs as precursors. The nitrogen content was up to 4 % with different forms in the carbon skeleton such as pyridine‐N, pyrrole‐N. The synergistic effect of ultra‐micropore (pore size <0.7 nm) and N‐containing groups endowed the materials with a high CO2 adsorption capacity, reaching 6.3 and 3.6 mmol g−1 at 0 and 25 °C under atmospheric pressure, respectively. In addition, the sufficient interaction between N‐containing groups and CO2 was demonstrated by solid‐state nuclear magnetic resonance spectroscopy, and the captured CO2 was possibly activated in the form of carbamate, which is conducive to subsequent conversion. Therefore, the supported catalyst with the as‐synthetic porous carbon material as the carrier and ZnII as catalytic sites was prepared and successfully applied for carboxylative cyclization of propargylic amine with CO2 to afford the 3‐benzyl‐5‐methyleneoxazolidin‐2‐one. The results showed that CO2 capture and in‐situ conversion work effectively to produce highly value‐added chemicals. In this process, the captured CO2 could be activated and fixed into chemicals in mild conditions. More importantly, the energy consumption in CO2 desorption and adsorbent regeneration could be avoided. The valorization of both solid waste and CO2 to valuable chemicals provides an elegant strategy of killing three birds with one stone. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed four-component carboxylative cyclization comprising propargylic amines, aryl iodides, CO2 and CO was developed. By selecting Et3N and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the base, respectively, both terminal and internal propargylic amines proceeded well facilitated by Pd(PPh3)2Cl2, affording the functionalized 2-oxazolones in moderate yields. This protocol enlarges the product diversity based on CO2 conversion and simultaneously provides a cooperative transformation route for both CO2 and CO. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis has emerged as an efficient route to transform CO2 into functionalized organic carbamates by photocatalysis. Herein, a catalyst-free carbamoyloxylation of arylacetones with CO2 and amines under visible light was developed for the synthesis of O-β-oxoalkyl carbamates in yields up to 93%. This protocol proceeded smoothly with the assistance of inexpensive carbon tetrabromide at room temperature under atmospheric CO2 pressure, leading to simultaneous construction of C–O and C–N bonds. Mechanism studies suggested the photoinduced hydrogen atom transfer (HAT) pathway followed by radical addition or single electron transfer (SET). [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction to valuable chemicals, especially fuels, is considered as a promising strategy to mitigate CO2 accumulation and tackle the energy crisis, among which photocatalysis is vital to achieve efficient and selective reduction of CO2. In this work, phosphorus-doped hollow polygonal g-C3N4 rods were prepared through phosphoric acid assisted self-assembly under hydrothermal conditions and subsequent thermal polymerization using phosphoric acid as the phosphorus source and melamine as the nitrogen-rich precursor. The resulting phosphorus-doped hollow polygonal g-C3N4 rods feature increased specific surface area, visible light absorption and photogenerated carrier separation and transfer efficiency according to the structure and photoelectric properties characterization. Coupled with an earth abundant metal-based complex, i.e. [Co(bpy)3]Cl2, as a co-catalyst, the phosphorus-doped hollow polygonal g-C3N4 rods deliver a CO evolution rate of up to 447.5 μmol g−1 h−1 with a selectivity of ca. 96%, being much higher compared to the pristine g-C3N4 (67.01 μmol g−1 h−1 with a selectivity of ca. 94%) resulting from the improved light harvesting and charge transfer to the co-catalyst. Remarkably, the phosphorus-doped hollow polygonal g-C3N4 rods can be reused 6 times while retaining constant catalytic activity in the photoreduction reaction. This work presents new insights into photocatalytic CO2 reduction by developing non-metal doping and hollow structural designs for semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

Monitoring the degradation state of hydraulic pumps is of great significance to the safe and stable operation of equipment. As an important step, feature extraction has always been challenging. The non-stationary and nonlinear characteristics of vibration signals are likely to weaken the performance of traditional features. The two-dimensional image representation of vibration signals can provide more information for feature extraction, but it is challenging to obtain sufficient information based on small-size images. To solve these problems, a method for feature extraction based on modified hierarchical decomposition (MHD) and image processing is proposed in this paper. First, a set of signals decomposed by MHD are converted into gray-scale images. Second, features from accelerated segment test (FAST) algorithm are applied to detecting the feature points of the gray-scale image. Third, the real part of Gabor filter bank is used to convolve the images, and the responses of feature points are used to calculate histograms that are regarded as feature vectors. The method for feature extraction fully acquires the multi-layered texture information of small-size images and removes the redundant information. Furthermore, support vector machine (SVM) and nondominated sorting genetic algorithm II (NSGA-II) are introduced to conduct feature selection and state identification. NSGA-II and SVM can conduct the joint optimization of these two goals. The details of the proposed method are validated using experimental data, and the results show that the highest recognition rate of our proposed method can reach 100%. The results of the comparison among the proposed method, local binary pattern (LBP), and one-dimensional ternary patterns (1D-TPs) certify the superiorities of the proposed method. It obtains the highest classification accuracy (99.7%–98%) and the lowest feature set dimension (13–10). [ABSTRACT FROM AUTHOR]

Bio‐derived lubricants, especially those derived from vegetable oils, are considered to be promising alternatives to mineral oil‐based lubricants due to the features of sustainability and environmental friendliness. In this work, the polyol ricinoleates were prepared by esterification of ricinoleic acid with trimethylolpropane (TMP), neopentyl glycol (NPG) and pentaerythritol (PE) respectively using Lewis acidic stannous oxide as an efficient heterogeneous catalyst, affording the polyol ricinoleates up to 99.7% yield. Remarkably, the solid catalyst was readily recovered and reused at least for five cycles without significant loss of activity. The resulting polyol ricinoleates products were structurally characterized by Fourier transform infrared spectroscopy (FT‐IR), 1H NMR, 13C NMR, electrospray ionization mass spectra (ESI‐MS); and were stable below 300°C through thermogravimetric analysis (TGA). Furthermore, the physicochemical and lubricating properties of as‐synthesized polyol esters were also evaluated including viscosity at 40 and 100°C, viscosity index (VI), pour point and flash point, thermal stability and wear scar diameter. To our delight, the performance indicators of the target products were comparable or better than the commercial lubricants, showing their potential as lubricant base oil. This work represents an alternative access to useful lubricant products via effective and selective conversion of non‐edible vegetable oil. [ABSTRACT FROM AUTHOR]

CO2 valorization into valuable chemicals has attracted much attention, among which carboxylative cyclization represents an appealing transformation strategy to synthesize heterocyclic compounds. Conventionally, the carboxylative cyclization comprises CO2 capture and subsequent nucleophilic attack of the resulting carboxylic anion to an unsaturated bond, by which the monofunctionalization of the unsaturated bond is realized and the heterocyclic compounds, such as 5-/6-membered cyclolactone, cyclocarbonate, and oxazolidinone, are accordingly generated. Nowadays, the CO2-participated multicomponent carboxylative cyclizations have evoked intense interest due to their ability to perform the bifunctionalization of the unsaturated bond in the ring-closing step, thus assembling complex molecules. Up to now, by activating the unsaturated bonds with functionalized reagents and designing cascade reactions of organometallic compounds, substituents including iodine, trifluoromethyl, perfluoroalkyl, alkyl, cyanoalkyl, allyl, aryl, phenoxy, allenyl, selenyl, amino, and phosphonyl groups have been incorporated into the cyclocarbonate or oxazolidinone compounds successfully through the multicomponent carboxylative cyclizations. Given the tremendous utility of this synthetic strategy in heterocyclic compound synthesis, this review summarizes the progress of multicomponent carboxylative cyclizations to spur the further development of this field. [ABSTRACT FROM AUTHOR]