Climate change has become a worldwide concern with the rapid rise of the atmospheric Co2 concentration. To mitigate Co2 emissions, the research and development efforts in Co2 capture and separation ...both from the stationary sources with high Co2 concentrations (e.g., coal-fired power plant flue gas) and directly from the atmosphere have grown significantly. Much progress has been achieved, especially within the last twenty years. In this perspective, we first briefly review the current status of carbon capture technologies including absorption, adsorption, membrane, biological capture, and cryogenic separation, and compare their advantages and disadvantages. Then, we focus mainly on the recent advances in the absorption, adsorption, and membrane technologies. Even though numerous optimizations in materials and processes have been pursued, implementing a single separation process is still quite energy-intensive or costly. To address the challenges, we provide our perspectives on future directions of Co2 capture research and development, that is, the combination of flue gas recycling and hybrid capture system, and one-step integrated Co2 capture and conversion system, as they have the potential to overcome the technical bottlenecks of single capture technologies, offering significant improvement in energy efficiency and cost-effectiveness.
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► CO2-TPD study provides an insight into the CO2 sorption mechanism over PEI-SBA-15-based MBS. ► The exposed PEI layer and the inner bulky PEI layer may exist and their proportions ...vary with PEI loading and sorption temperature. ► A two-layer model for CO2 sorption over PEI/SBA-15 sorbent is proposed and discussed.
In this work, we conducted a study on temperature-programmed desorption (TPD) of CO2 over molecular basket sorbent (MBS) consisting of polyethylenimine (PEI) immobilized in mesoporous silica SBA-15. A series of MBS sorbents with different PEI loadings in SBA-15 have been studied for CO2-TPD to gain an insight into the fundamental characteristics of CO2 sorption/desorption mechanism. Effects of sorption temperature, sorption time, and PEI molecular weight on the CO2 sorption capacity and desorption behavior of 50wt% PEI/SBA-15 sorbent were also examined. The results show that two PEI layers, i.e., the exposed PEI layer and the inner bulky PEI layer may exist in PEI/SBA-15 sorbents, and their proportions vary with PEI loading and sorption temperature. Consequently, a two-layer model for CO2 sorption over PEI/SBA-15 sorbent is proposed, which rationalizes the sorption results with consideration of CO2 sorption kinetics and thermodynamics. It was also found that CO2 sorption capacity decreases with increasing PEI molecular weight, which may be mainly attributed to the decrease of primary amine content and the increase of tertiary amine content as well as increased interactions between polymeric chains in the PEI molecules.
Highly efficient SnO2−x/g-C3N4 composite photocatalysts were synthesized using simple calcination of g-C3N4 and Sn6O4(OH)4. The synthesized composite exhibited excellent photocatalytic performance ...for rhodamine B (RhB) degradation under visible light irradiation. The optimal RhB degradation rate of the composite was 0.088min−1, which was 8.8 times higher than that of g-C3N4. The SnO2−x/g-C3N4 composite also showed high photocatalytic activity for CO2 reduction and photodegradation of other organic compounds. Various techniques including Brunauer–Emmett–Teller method (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and an electrochemical method were applied to determine the origin of the enhanced photoactivity of SnO2−x/g-C3N4. Results indicated that the introduction of SnO2−x on g-C3N4 increased its surface area and enhanced light absorption performance. More importantly, a hetero-junction structure was formed between SnO2−x and g-C3N4, which efficiently promoted the separation of electron–hole pairs by a direct Z-scheme mechanism to enhance the photocatalytic activity. This study might represent an important step for the conversion of solar energy using cost-efficient materials.
•Novel Z-scheme SnO2−x/g-C3N4 composites are prepared and tested.•SnO2−x/g-C3N4 composite degrades RhB 8.8 times faster than g-C3N4 under visible light.•SnO2−x/g-C3N4 composites also show high activity in photocatalytic CO2 reduction.•The Z-scheme mechanism is verified by reactive species trapping experiment.
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•The selective promotion of CH3OH in CO2 hydrogenation correlates to Pd-Cu alloy content.•Pd-Cu combination shifts adsorption towards weakly-bonded H2 and CO2.•Weakly-bonded H2 and ...CO2 species over Pd-Cu appear to correlate with CH3OH promotion.•DFT study rationalizes CO2 adsorption and initial hydrogenation on Pd-Cu bimetallic surface.
A strong synergetic effect was observed in our previous work on Pd-Cu bimetallic catalysts for CH3OH formation from CO2 hydrogenation when the Pd/(Pd + Cu) atomic ratio lied within 0.25–0.34. In the present study, the importance of Pd-Cu alloy in selective CH3OH promotion was evidenced and correlated with alloy contents quantitatively through X-ray diffraction (XRD), scanning transmission electron spectroscopy with energy-dispersive X-ray spectroscopy (STEM/EDS), and H2-O2 titration and N2O titration. The surface chemical properties of Pd-Cu combinations were characterized by H2-/CO2-temperature-programmed desorption (TPD), diffuse reflectance infrared FT spectroscopy (DRIFTS), and density functional theory (DFT), and experimentally evaluated along with monometallic counterparts. Detailed characterization results reveal a unique shift in adsorption towards weakly-bonded H2 and CO2 on Pd-Cu bimetallic surface which appear to correlate to the CH3OH promotion. DFT calculations on adsorption properties of H2 and CO2 show good agreement with the observation from TPD experiments. DFT study also provides insights into the impact of Pd-Cu combination on the activation and initial hydrogenation of CO2 to formate (HCOO∗) and hydrocarboxyl (COOH∗) intermediates. HCOO∗ formation was found to be kinetically more favored than COOH∗ on monometallic Cu and Pd-Cu surfaces. The lowest barrier for HCOO∗ formation was observed at Pd/(Pd + Cu) atomic ratio of 0.33, around which a good CO2 conversion and high methanol selectivity were achieved experimentally.
Briefing: To tackle the complexity of human and social factors in manufacturing systems, parallel manufacturing for industrial metaverses is proposed as a new paradigm in smart manufacturing for ...effective and efficient operations of those systems, where Cyber-Physical-Social Systems (CPSSs) and the Internet of Minds (IoM) are regarded as its infrastructures and the "Artificial systems", "Computational experiments" and "Parallel execution" (ACP) method is its methodological foundation for parallel evolution, closed-loop feedback, and collaborative optimization. In parallel manufacturing, social demands are analyzed and extracted from social intelligence for product R&D and production planning, and digital workers and robotic workers perform the majority of the physical and mental work instead of human workers, contributing to the realization of low-cost, high-efficiency and zero-inventory manufacturing. A variety of advanced technologies such as Knowledge Automation (KA), blockchain, crowdsourcing and Decentralized Autonomous Organizations (DAOs) provide powerful support for the construction of parallel manufacturing, which holds the promise of breaking the constraints of resource and capacity, and the limitations of time and space. Finally, the effectiveness of parallel manufacturing is verified by taking the workflow of customized shoes as a case, especially the unmanned production line named FlexVega.
Abstract
The purpose of this study is to evaluate the efficacy of prophylactic use amphotericin B in patients with hematologic disorders complicated by neutropenia. We searched the PubMed, EMBASE, ...The Cochrane Library, CBM, CNKI, VIP and WanFang Data database and the China Clinical Trials Registry (
www.chictr.org.cn
) to collect randomized controlled trials (RCTs) of amphotericin B for patients with hematologic disorders complicated by neutropenia from inception to May 2023. The Cochrane risk-of-bias tool for RCTs was used to assess the bias risk of the included studies. The meta-analysis was performed using RevMan 5.3 software. A total of 6 studies with a total of 1019 patients were included. The results of the meta-analysis showed that the treatment group was superior to the control group in terms of the fungal infection rate, and the differences were statistically significant RR = 0.47, 95% CI (0.32, 0.69),
P
< 0.0001. There was no significant difference between the two groups in terms of the mortality RR = 0.87, 95% CI (0.61, 1.23),
P
= 0.43 and the incidence of colonization OR = 0.51, 95% CI (0.25, 1.03),
P
= 0.06. The evidence shows that amphotericin B prophylactic use for patients with hematologic disorders complicated by neutropenia can decrease the fungal infection rate. However, there was no significant difference in reducing mortality or the incidence of colonization. Due to the limited quality and quantity of the included studies, more high-quality studies are needed to verify the above conclusion.
•We develop a new low cost clay-supported polyethyleneamine sorbent for CO2 capture.•Effects of acid- and alkaline-treatments on the porosity-enhancement of clays.•Effects of the PEI loading, ...sorption temperature, and H2O addition on CO2 sorption.•The PEI/HCl-modifed montmorillonite sorbent is regenerable and thermally stable.
A new inexpensive inorganic–organic composite sorbent for CO2 capture was prepared by the immobilization of a branched polyethyleneimine (PEI) onto porosity-enhanced clays using the wet impregnation method. In the composite, a low cost and naturally abundant clays (e.g. kaolinite and montmorillonite) was used as the supporting material, which was pre-modified by acid- or alkaline-treatment to improve its textural properties, i.e. pore volume and surface area, for accommodating the CO2-philic PEI. Among the modified clays, the montmorillonite modified by 6M HCl (Mon_HCl_6M) showed the highest porosity with the pore volume of 0.71cm3/g from 0.16cm3/g, and BET surface area of 253m2/g from 72m2/g. The cost of the Mon_HCl_6M was estimated as $0.14/kg, which was significantly lower than reported supporting materials for the amine-based sorbents for CO2 capture. At the optimal PEI loading of 50 wt% on the Mon_HCl_6M support, the CO2 sorption capacity reached 112mg CO2/g-sorbent at 75°C under dry condition, which can be further enhanced to 142mg CO2/g-sorbent with the moisture addition (ca. 3vol%) due to the change in the interaction mechanism between CO2 and amine in the presence of moisture. Moreover, the PEI/Mon_HCl_6M sorbent showed a good regenerability for 10 sorption–desorption cycles tested and a good thermal stability in the temperature range of CO2 sorption (75°C) and desorption (100°C).
A series of vanadium doped cryptomelane-type manganese oxide (V-OMS-2) catalysts were prepared by a simple, low-cost reflux method, and investigated for one-pot imine synthesis from oxidative ...coupling of benzyl alcohol and aniline with air. The physicochemical properties of the V-OMS-2 catalysts were characterized by various techniques including XRD, BET, SEM, TEM, XPS, H2-TPR and NH3-TPD. It was found that the surface area, Lewis acid sites, the amount of Mn3+ component and active surface oxygen species were much improved with vanadium doping. Consequently, the activity of V-OMS-2 catalyst for oxidative coupling of benzyl alcohol and aniline to imine was enhanced. The highest conversion and the imine yield were obtained over the 3 mol% V-OMS-2 catalyst, being ∼99% and 92%, respectively. Higher vanadium doping (≥ 6 mol%), however, hindered the preservation of OMS-2 crystal structure, leading to a drop in the catalytic performance. The high specific surface area was suggested to be the key contributor to the high catalytic activity of 3% V-OMS-2(1) catalyst. Among the vanadium precursors studied, the catalyst prepared with vanadium pentoxide exhibited a much higher catalytic activity, which can be attributed to its larger surface area, unique mesoporous structure, increased Lewis acid sites and more readily available surface oxygen species. In addition, the stability and recyclability of the catalyst were also studied, and the reaction mechanism was discussed.
•V-doped OMS-2 catalysts were studied for imine synthesis from air-oxidative coupling of benzyl alcohol and aniline.•3%V-OMS-2(1) catalyst showed the best benzyl alcohol conversion of >99% and highest imine yield of 92%.•The activity promotion was related to the increased surface area, acid sites and active surface oxygen species by V doping.•The vanadium precursor influenced the V-OMS-2 catalyst structure and consequently its performance for imine synthesis.
The damage process and failure mechanisms were analyzed by a series of quasi-static compressive experiments of seven materials including pure epoxy (EP), three different PPI (pores per linear inch) ...foam nickel-iron, and three different PPI foam nickel/iron-epoxy interpenetrating phase composites (IPC). Plotting the stress–strain curves of different materials, their change rules are discussed, then the effective elastic modulus and yield limit of the materials are provided, and the energy absorption properties of different materials are analyzed by the stress–strain curves. It was found that the effective elastic modulus and specific stiffness of the three IPC materials were higher than pure foam nickel-iron. The brittleness of epoxy can be obviously changed by selecting a suitable PPI foam nickel-iron composited with it. The unit volume energy absorption rate of foam nickel/iron-epoxy was significantly higher than pure epoxy and pure foam nickel-iron. It was also found that the energy absorption rate decreased with the increase in PPI. The stress relaxation rate decreased first and then increased with the increase in PPI. The creep behavior of the three composites was obvious in the creep elastic stage, and the creep rate increased with the increase in PPI. The creep rate decreased with the increase in PPI in the creep transition stage.
The catalyst 25N3ZA prepared by impregnation co-precipitation(ICP) shows higher activity of methanation than that of impregnation (IP), and its CO conversion of CO was as high as 91.2% at reaction ...conditions of 325°C, 10,000mLg−1h−1 and 1.5MPa. Superior performance can be attributed to (i) better dispersion of Ni on the γ-Al2O3 support by ICP; (ii) Zr doping improved the dispersion of Ni as well the hydrogen-promoted dissociation of CO. Display omitted
•Two types of catalysts were prepared by impregnation (IP) and impregnation coprecipitation (ICP) methods.•ICP catalyst showed better performance of methanation than that of IP catalyst in slurry reactor.•ICP method is favor for the formation of small size Ni particles and more reducible NiO.•Zr doping can moderate the interaction between Ni and γ-Al2O3 support and promote the dispersion of Ni.
Syngas methanation was performed at 280–330°C in a stirred-slurry reactor with Zr-doped Ni/γ-Al2O3 catalysts. The catalysts were prepared using impregnation (IP) and impregnation–coprecipitation (ICP) methods. The catalyst 25Ni3Zr/γ-Al2O3 (ICP) had relatively high activity in syngas methanation and the water gas shift (WGS) reaction. A high CO conversion, ∼91.2%, was obtained at 325°C under 1.5MPa pressure, with a syngas flow of 10,000mLg−1h−1. However, the selectivity of CH4 over 25Ni3Zr/γ-Al2O3 (ICP) was 85.2%, which was slightly lower than that of 25Ni3Zr/γ-Al2O3 (IP), because of enhancement of the WGS reaction. The catalysts were characterized using temperature-programmed reduction, X-ray diffraction, and transmission electron microscopy; the results indicated that Ni was well dispersed on the γ-Al2O3 support by the ICP method. Zr doping improved Ni dispersion and H2-promoted dissociation of CO. Furthermore, it was found that the larger amount of reducible Ni formed using the ICP method gave a better catalytic performance.
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