Sustainable Chemistry for Climate Action最新文献

To realize a sustainable alternative to fossil fuels, carbon neutral sources such as biowaste should be converted to biooil. This paper reports the results of our study on the catalytic liquefaction of various organic waste (mandarin peel, coffee grounds and cocoa shell) to synthesize an oil which can be used as a sustainable fuel. Out of the tested reactions, spent coffee ground liquefaction proved to yield the best results when catalyzed by phosphotungstic acid (PTA). Increasing the catalyst loading resulted in an increasing yield, with the maximum yield of 40 % obtained with a catalyst loading of 38 wt%. The resulting oil contained compounds mainly in the desired C8-16 range (79 %) that is required for jet fuel. While most of these compounds were oxygenated compounds an upgrading reaction should allow the oil to be used as a sustainable jet fuel alternative.

Natural fibres could be used as one of the raw materials for the production of engineering materials. They have the advantage of low density, light weight, biodegrability and the capacity to reprocess to a certain extent. There are certain limitations of such fibres when formed composites with synthetic polymers like high degree of moisture absorption, and lack of affinity between fiber and the matrix. The presence of polar components like hemicellulose and lignin content in the fibres are the reason for these materials to be hydrophilic. This issue has been addressed by treating fiber surface with variety of chemical reagents which is reported to improve mechanical and adhesion property between fiber and the matrix. Chemical treatments can be based on reactions involving esterification methods like acetylation and benzylation, graft polymerization methods like treatments with triazine, isocyanates and maleic anhydride, silane coupling agents, other treatments include alkali, acrylation and acrylonitrile, permanganate, peroxide treatments and also steric acid, sodium chloride and oleoyl chlorite. Surface modification of fibres reduces its moisture absorption tendency and improves their mechanical properties thereby increasing durability of the composites.

Direct carbon dioxide (CO₂) conversion into valuable chemicals like dimethyl carbonate (DMC) is an atom efficient avenue for CO₂ utilization but greatly challenges the catalyst designation because the requirement of multiple active sites. Herein, regulation of the basicity of porous poly(ionic liquid)s (PPILs) was reached by post-treating epoxy-functional precursor and utilizing 1,5,7-triazodicyclic [4.4.0] Dec-5-ene (TBD) to convert epoxy functional ionic moieties into the multifunctional sites with nucleophilic-leaving capable anions, hydroxyl group and TBD derived basic sites. The constructed catalyst was highly active in the one-pot and two-step DMC synthesis by coupling the CO₂ cycloaddition with epoxide and successive transesterification. A high yield up to 93% was observed by using atmospheric CO₂ under the metal-solvent-additive free condition. Stable reusability and extendibility by using multiple epoxides further reveal the efficiency and potentiality of the present catalyst in CO₂ fixation.

A low temperature CO₂ methanation is a thermodynamically favorable route to produce highly selective methane while preventing catalyst deactivation. Ni-Ba/Sm₂O₃ catalysts synthesized using one-pot hydrothermal method exhibited enhanced reducibility with high CO₂ adsorption capacity to achieve CO₂ conversion at low temperatures. CO₂ conversion occurred at 200 °C with 5% conversion, progressively increasing to reach equilibrium at 400 °C with 100% selectivity to methane. BaO promotes surface oxygen vacancy in Sm₂O₃, which is responsible for forming bidentate formate species during CO₂ methanation. Comparative DRIFTS analysis with Ni-Ba/Sm₂O₃ synthesized using impregnation indicates the catalysts followed different mechanistic pathways depending on the amount of surface oxygen vacancy generated by BaO/Sm₂O₃ proximity.

Selective adsorption of CO₂ from biogas allows isolating biomethane, which can then be used as a direct substitute for natural gas. The microporous zeotype SAPO-34 is a suitable material for CO₂ adsorption because it can achieve high working capacity at relatively mild regeneration conditions. In industrial applications, adsorbents need to be shaped into a macroscopic format (e.g. beads, pellets) in order to reduce the pressure drop over the adsorption column. Typically, an inert binder is added to the powder to achieve the desired format. In this work, novel hierarchically porous binderless SAPO-34 beads with a diameter in the range 0.7–1.2 mm were synthesised employing an ion-exchange resin as a hard template. The interior of the beads consisted mostly of small SAPO-34 crystals (< 0.3 μm) interconnected to each other and thus generating a network of meso‑ and macropores between them, as demonstrated by XRD and SEM. Around several of the beads, a crystal overgrowth was observed consisting mostly of larger SAPO-34 crystals (1–25 μm). The SAPO beads displayed good CO₂ adsorption capacity (3.0 mmol g⁻¹ at 1 bar), which was higher than that of binder-containing SAPO-34 extrudates (2.4 mmol g⁻¹ at 1 bar), but slightly lower compared to SAPO-34 in powder format (3.4 mmol g⁻¹ at 1 bar). Furthermore, the SAPO-34 beads displayed high CO₂/CH₄ selectivity (8, at partial pressures mimicking biogas, i.e. 0.4 bar CO₂ and 0.6 bar CH₄) as well as high CO₂/N₂ selectivity (33, at partial pressures mimicking flue gas, i.e. 0.15 bar CO₂ and 0.85 bar N₂). Notably, a high CO₂ working capacity of 1.8 mmol g⁻¹ was estimated based on the adsorption isotherm between 1 and 0.2 bar, and this value has the potential to be further improved by increasing the adsorption pressure to > 1 bar.

Defossilizing ethylene production to decrease ${\text{CO}}_2$ emissions is an integral challenge in the context of climate change, as ethylene is one of the most important bulk chemicals. Electrochemical ${\text{CO}}_2$ reduction is a promising alternative to conventional steam cracking, reducing the carbon footprint of ethylene production when coupled with renewable energy sources. In this work, we present the optimization of a boron-doped copper catalyst towards higher selectivity for ethylene. The method for catalyst preparation is optimized, obtaining larger batch sizes while maintaining high ethylene selectivity. Additionally, life cycle assessment is applied to investigate the environmental impacts of electrochemical ${\text{CO}}_2$ reduction and to compare its carbon footprint with alternative pathways for ethylene production. Altogether, the scaled-up catalyst achieves promising electrochemical results while significantly reducing the carbon footprint for ethylene production in comparison to the conventional production pathway when combined with low-emission energy.

The contribution of greenhouse gas and anthropogenic CO₂ to climate change is an undeniably issue that needs urgent attention from the environmental point of view. Global warming, a consequence of continued CO₂ emissions will gradually result in ecosystem disruption and drought. With the increasing problem of greenhouse gas (GHG) and the established environmentally unfriendly consequences associated with it, carbon capture and storage (CCS) was proposed as a measure to successfully reduce carbon footprints and a process of choice in proffering solutions to this challenge. To meet the Paris agreement's target of maintaining the global temperature rise below 2 °C necessitates the capture and removal of up to 20 Gt CO₂ per annum by the end of the century. However, going by the current global CO₂ capture and storage capacity of 0.0385 Gt CO₂/annum (including the current direct air capture (DAC) capacity of 9,000 tons CO₂/annum), it will take close to 21,000 years to achieve this set goal. Hence, the need to adopt sustainable low-temperature sorbent technology with efficient adsorption capabilities that will meet up with the bourgeoning operating cost and energy demand for DAC technology. In this review, sustainable and emerging adsorbent materials and technologies employed in carbon capture and storage were highlighted. Also, economic, and environmental benefits and public perception of carbon capture technology were enumerated.

Excess carbon dioxide (CO₂) in the atmosphere is causing great harm to the environment. Silicoaluminophosphate (SAPO) zeotypes have attracted great attention in CO₂ capture. In this review, we comprehensively summarized and discussed the advances in the CO₂ adsorption by SAPO zeotypes, the factors affecting the CO₂ capture such as topologies, cation types, and amine modifications, and the interaction between the H₂O, SO_x, and NO_x and the framework of SAPOs as well as their influence on the CO₂ adsorption performance. At the end of the review, we raised the key challenges, current trends in the development of SAPO zeotypes, future research directions, and possible solutions to achieve the deployment of effective SAPO materials in CO₂ capture.

This study presents the application of biosynthesized silver nanoparticles (AgNPs) for modifying the surface of ultrafiltration membranes to confer antimicrobial properties. The AgNPs were synthesized using leaf extract of the medicinal plant Mimusops elengi L, and their characterization was carried out using UV spectroscopy, FTIR, XRD, FESEM, HRTEM, and AFM analyses. The optimal conditions for the synthesis of AgNPs were determined to be 240 min of reaction time, pH 9.5, 1:1 (v/v) ratio of initial concentration of precursor to bio-extract, and 323 K temperature. The synthesized AgNPs were found to be spherical with an average size of 20 nm and crystalline in nature. The AgNPs were then deposited on flat sheet polyether sulfone (PES) membranes (MWCO 30 kDa) using the dip coating technique. The deposition of AgNPs on the membrane surface was confirmed using FESEM and EDX analysis. The resulting AgNPs-incorporated membrane demonstrated effective antibacterial activity against E.coli. These findings highlight the potential of biosynthesized AgNPs for developing functionalized ultrafiltration membranes with antimicrobial properties.

This work demonstrates a green conversion of waste cooking oil in a continuous mode into esters, fatty acids and hydrocarbons within seconds via cold plasma catalytic approaches. Up to 60 wt.% gaseous hydrocarbons (C₁C₆) was achieved within 11 s reaction time in hydrogen environment. Products distribution and selectivity can be easily tuned e.g. up to 43 wt.% esters (in the presence of Ni/Al₂O₃ in N₂ environment at 30 W) or up to 46 wt.% fatty acids to be obtained (BaTiO₃ packing under N₂ at 30 W). The selectivity of products is strongly influenced by the environment, e.g. H₂ environment promoting fatty acid methyl esters formation whereas hydrocarbons are dominant in N₂ environment.