Abstract ：

CO2-based biodegradable plastics are potential solutions for reducing fossil-fuel consumption, mitigating climate change, and addressing plastic pollution by reducing plastic waste accumulation. Poly(propylene carbonate) (PPC) is a commercial CO2-based biodegradable plastic derived from CO2 and propylene oxide (PO), and it has been used in flexible packaging and mulching film applications. However, the environmental performance of PPC is still unknown. Since China has become the largest producer of PPC in the world, this study takes the industrial production technologies of PPC and its feedstocks in China as an example. The cradle-to-gate life-cycle inventory of PPC resin was compiled, and life-cycle impact assessment was performed to assess the environmental impacts of PPC and mitigation potentials based on the ReCiPe 2016 method. Results indicated that PPC synthesis has the greatest impact on the environment (contributions of 38-95% of 16 environmental impact categories), followed by PO production. Technological innovation and renewable energy substitution scenarios were developed to explore the mitigation potential of PPC. We found that supercritical polymerization technology has greater mitigation potential than photovoltaic power substitution, which could reduce 17 impact categories of PPC by 17-96% by reducing energy and dichloromethane consumption during PPC synthesis. Photovoltaic power substitution reduced 2-22% of 11 impact categories of PPC. Compared with conventional plastics, PPC had advantages over conventional plastics in terms of 17 impact categories. The environmental impacts of PPC were 2-98% lower than those of conventional plastics. This study emphasizes the importance of technological innovation in reducing the lifecycle environmental impacts of PPC and provides a basis for environmental performance of CO2-based biodegradable plastics and the potential to replace conventional plastics. Policy implications for innovations in synthesis technology, sustainable feedstocks and environmental impact assessment were proposed, which could provide valuable insights for practitioners and policymakers in enhancing the sustainability of the plastics industry through biodegradable plastic alternatives.

Keyword ：

CO2-based copolymers CO2-based plastics Carbon neutrality Life cycle assessment Biodegradable plastics Poly(propylene carbonate)

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Abstract ：

Atomically well-dispersed platinum catalysts play a vital role in various chemical processes such as direct dehydrogenation of propane (PDH), due to their high performance originated from high atom utilization. However, these catalysts suffer from complex preparation methods, and preparing atomically dispersed Pt-based catalysts with feasible methods remains challenging. Herein, we report a convenient method to prepare efficient atomically dispersed Pt/C catalysts for PDH by sulfur doping into the carbon support by simple cyclohexane impregnation method. The prepared atomically well-dispersed catalysts possess strong interactions between Pt and carbon support, which led to improved exposure of active sites and higher propylene formation rate compared to that without sulfur doping. Sintering of the Pt species was also inhibited and stability was improved by 47%. Propylene selectivity also showed a positive correlation with the amount of sulfur doping. The propane conversion first increased and then decreased, which was due to the loss of sulfur during the reaction that caused the agglomeration of Pt and the evolution of structure. It was found that the maximum catalytic activity appeared with Pt clusters of similar to 0.71 nm with an average Pt-Pt coordination number of 3.1 and Pt-Pt bond distance of 3.09 angstrom.

Keyword ：

Dehydrogenation of propane Sulfur-doped carbon Geometric configuration Metal-support interactions Catalyst Electronic structure

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Abstract ：

The propane oxidation dehydrogenation assisted by CO2 (CO2-ODHP) is currently a hot research topic, not only to meet growing demand of propylene but also to favor the CO2 neutralization. In present work, a series of CrOx@S1-n-1.0 with different Cr contents (n= 2.2, 3.6 and 4.5 wt%) is synthesized based on a small gas molecule directing synthesis strategy, wherein the gaseous CO of 1.0 MPa was in situ introduced in the synthesis system to regulate the interaction and dispersion of CrOx over silicalite-1 (S1) support. The characterization results of XRD, XPS, H2-TPR, and Raman indicate that the CO can affect the oxidation state and dispersion of Cr species. As observed, the Cr species were highly dispersed over CrOx@S1-3.6 %-1.0 (in the form of Cr6+ valance state), which however would aggregate to generate Cr2O3 nanoparticles over the CrOx@S1-3.6 %-0a prepared by impregnation method in absence of CO. The activity measurement indicates that the CrOx@S1-3.6 %-1.0 possesses the highest activity by displaying an average propane conversion of 50.4 % and CO2 conversion of 23.6 % at 600 degrees C, which surpasses most of the literature reports. The CO2-ODHP reaction mechanism was further investigated by in situ DRIFTS, which indicates that dissociated H of propane can react with CO2 to form formate (-COOH), in turn further reacts with H to produce byproducts CO and H2O, and the formate species can also react with the CrO3 active site to form bicarbonate species (HCO-3). Generally, present work has proposed a small gas molecule directing strategy to adjust the dispersions and chemical states of the loaded guest meals over catalytic support. The study of present work would contribute to other highly efficient catalyst design.

Keyword ：

Carbon dioxide Chromium oxides Silicalite-1 Oxidative dehydrogenation of propane

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Abstract ：

The structural integrity of traditional Chinese village residences may be compromised due to inadequate connections between the timber frame and infill walls, coupled with the weak cohesiveness of clay mud. Among the various damage mechanisms resulting from earthquakes, the out-of-plane collapse of infill walls is a recurrent and significant concern. The goal of this research is to investigate the feasibility and effectiveness of a poly-propylene (PP) band mesh reinforcement approach for a traditional timber frame with mud and rubble infill walls. The ultimate goals are to prevent out-of-plane collapse, improve the collaborative performance of the structure, reduce seismic vulnerability, and safeguard the architectural heritage of traditional dwellings. With careful consideration of their aesthetics, the study centers on timber frames with mud and rubble infill walls strengthened by a polypropylene (PP) band mesh and cement mortar on one side. A series of experiments were conducted based on out-of-plane cyclic one-way tests of four full-scale specimens. Different loading surfaces and reinforcing PP grid sizes with and without window openings were investigated to characterize the out-of-plane behavior of the reinforced hybrid walls. The damage evolution, failure modes, force-displacement curves, out-of -plane profile characteristics, stiffness, strength, and energy dissipation were described. All the reinforced walls exhibited marked improvements out-of-plane lateral capacity, with enhancements of approximately 120% and 162%, and stiffness increases of approximately 105% and 200%, compared to the unreinforced walls. The minimal out-of-plane displacement observed on the reinforcement side was also accompanied by significant increase in integrity and ductility.

Keyword ：

Traditional village dwellings Out -of -plane behavior Seismic reinforcement Polypropylene band meshes Timber frame with mud -rubble infill

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Abstract ：

We prepare alpha-Fe2O3 nanosheet supported 0.38, 0.81, and 1.36 wt% Au (average particle size = 4.0 nm) nanocatalysts, and investigate their performance and mechanism for the selective catalytic oxidation of isopropanol to acetone. In the presence of 1.2 vol% isopropanol and 40 vol% O-2, 1.36 wt% Au/alpha-Fe2O3 exhibits excellent catalytic performance, due to its moderate acidic sites and better redox properties, with acetone selectivity and yield being as high as 99% and 95% at 220 degrees C, respectively. In addition to acetone, little propylene, acetic acid, acetaldehyde, methyl vinyl ketone, 2-butanone, isopropyl ether, isopropyl acetate, 3-penten-2-one, isopropyl acrylate, isopropyl propionate, and 2, 4-dimethylfuran are detected. The possible reaction mechanism is proposed for the selective catalytic oxidation of isopropanol to acetone over the present catalysts. We believe the present selective catalytic oxidation method, rather than the traditional complete catalytic oxidation method, provides an alternative and economic method for VOCs emissions control.

Keyword ：

Supported Au nanocatalysts Selective catalytic oxidation Volatile organic compounds Resource utilization alpha-Fe(2)O(3)nanosheet

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Abstract ：

Sn-containing dendritic mesoporous silica nanoparticles (Sn-DMSNs) were successfully prepared by the in-situ co-assembly method. Sn-DMSNs preserve original structural characteristics with three-dimensional and center-radial pore structure. The nanoparticle sizes of Sn-DMSNs can be controlled systematically from 170 nm to 360 nm depending on the molar ratio of NaSal/CTAB. Sn species are incorporated into the matrix of silica and the highly dispersed SnOx species are achieved. Sn-DMSNs catalysts exhibit excellent catalytic performance and stability in the propane dehydrogenation. The highly dispersed SnOx species rather than polymeric SnOx or crystalline SnO2 species contribute to the activation of propane and formation of propylene. The molar ratio of NaSal/CTAB also shows an important role in the structure of support and SnOx species. The excellent stability of Sn-DMSNs catalysts can be ascribed to the good ability to restrain coke formation and strong interaction between SnOx species and silica. The effect of potassium on Sn-DMSNs catalyst is also investigated.

Keyword ：

Propane dehydrogenation K-modification Size effect SnOx-silica interaction Dendritic mesoporous silica nanospheres

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Abstract ：

This paper focused on VOCs and their source apportionment in urban Beijing. Our monitoring measured 52 VOCs in July 2014 and January 2015. The concentration of VOCs was in the range of 14.595.2 ppb in July and 2.193.1 ppb in January, with the top five compounds of toluene (10.7%), ethane (6.9%), ethylene (6.3%), n-butane (5.7%), and propane (5.6%) in July and ethylene (14.7%), n-butane (14.2%), ethane (9.6%), propylene (8.0%), toluene (7.9%), and benzene (6.9%) in January. The ratio of VOCs to CO reached 0.059 in July and 0.022 in January on average. These differences implied a potential seasonal difference in the VOC source contribution. Then, we conducted a source apportionment study based on 21 major VOCs and CO by using probabilistic matrix factorization (PMF) receptor model. According to the similarity between the PMF analysis profiles and the known source profiles, combustion sources, petrochemical industry sources, solvent utilization sources, and gasoline evaporation sources were identified. The correlation coefficient (R) between the PMF analysis profile and the source profile reached 0.680.87 in July and 0.530.92 in January. The better apportionment performance in July was mainly due to the use of intensive VOC observations at a 3-h resolution. When we conducted another PMF source apportionment for July based on 12-h resolved concentration input, the R values decreased to 0.470.73. Thus, the PMF model depends heavily on the sample number of concentration inputs, and intensive observation is more propitious. Our PMF apportionment results showed that combustion sources, petrochemical industry, solvent utilization, gasoline evaporation, and other sources contributed ambient VOCs in Beijing urban areas of 13.7 ppb, 5.1 ppb, 7.7 ppb, 12.8 ppb, and 3.3 ppb in July and 13.2 ppb, 2.0 ppb, 5.7 ppb, 6.6 ppb, and 1.0 ppb in January, respectively, on a monthly average. These apportionment results match well with the 2013 VOC emission inventory calculated by this study, but also presented significant seasonal differences in the petrochemical industry and gasoline evaporation, in which VOC emissions strongly respond to environmental temperature.

Keyword ：

VOCs Sensitivity study PMF source apportionment Emission inventory validation

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Abstract ：

Mesoporous organosilica membranes were synthesized by sol-gel and dip-coating method using 1,2-bis (triethoxysilyl) ethane (BTESE) as precursor, triblock copolymer poly (ethylene oxide)-block-poly (propylene oxide) block-poly (ethylene oxide) (P123) as surfactant template. After silylated with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES,C8) by post-grafting approach, the membranes were used for the separation of hazardous volatile organic compounds (VOCs) from water via pervaporation process. The results show that ethanol-extraction is considerably effective to remove the surfactant template. The membranes show a smooth surface and a sharp pore size distribution centered at 3.5 nm. The hydrophobic property has been enhanced after silylated with PFOTES, leading to a water contact angle of (105 +/- 0.11)degrees. Hydrophobic mesoporous organosilica membranes are selective toward VOCs and show the highest total flux of 0.36 kgm(-2)h(-1) for methyl tert-butyl ether (MTBE) aqueous solution and the highest MTBE/water separation factor of 27.9. The pervaporation performance depends on the affinity between VOCs and grafted C8 groups. Repeated separation experiments reveal that the membranes are durable in aqueous solution due to the presence of water-resistant Si-C bonds within the framework.

Keyword ：

Mesoporous organosilica membranes Volatile organic compounds Hydrophobic Pervaporation

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Abstract ：

A major impediment in photodynamic therapy (PDT) against hypoxic tumors is that the O-2-dependent PDT is seriously limited by the intrinsic hypoxic feature. Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is a key transcription factor in tumor development and especially accumulates in hypoxic tumors and has been recognized as a novel therapeutic target. Herein, we developed small molecule HIF-1 alpha inhibitor Doxy and IR780 photosensitizer co-incorporated methoxy poly(ethylene glycol)-b-poly-(propylene sulfide) (mPEG(50)-b-PPS45) nanoparticles (NPs/ID) as an ROS-responsive theranostic system designed to enhance PDT efficiency by combining the benefits of anti-HIF-1 alpha therapy and ATP depletion. NPs/ID with reinforced phototherapy response in hypoxic tumors displayed enhanced photocytotoxicity compared to NPs/I that only exhibited the PDT effect. On the other hand, NPs/ID have the capacity to reduce the supply of intracellular ATP and destabilize the intracellular redox homeostasis for enough ROS generation by suppressing the HIF-1 alpha expression, thereby facilitating the therapeutic efficiency of PDT. Significantly, NPs/ID displayed effective tumor targeting and NIR imaging ability and an improved in vivo efficacy in a xenograft MDA-MB-231 mouse tumor model compared with bare PDT. These findings demonstrate that the ROS-responsive theranostic NPs/ID with special anti-HIF-1 alpha and ATP depletion behavior represent an attractive approach for overcoming the problems of PDT in hypoxic tumors.

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Abstract ：

研究了新型耐腐蚀换热器的制作材料,旨在避免烟气余热回收时,因烟气温度低于其酸露点温度而产生的低温腐蚀.采用石墨填充聚全氟乙丙烯(fluorinated ethylene propylene,FEP),并添加一定量的碳纤维,制备出导热性能较好、抗冲击且耐腐蚀的石墨改性FEP导热材料.通过导热性能、力学性能及耐腐蚀性能研究,确定了适用于制作烟气余热回收系统中换热器的复合材料中石墨的填充质量分数.实验表明,石墨的质量分数越高,导热复合材料的热导率越大,但其拉伸强度、断裂伸长率和冲击强度会随着石墨填充质量分数升高逐渐降低.

Keyword ：

导热复合材料 石墨 聚全氟乙丙烯

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