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Thin and oriented zeolite films are important for advanced separations, catalysis, and sensing. Strategies for tailoring zeolites for applications include controlling their crystal size, shape, and orientation. Here, three siliceous DDR zeolite ultrathin films with different orientations achieved by homoepitaxial growth from 60 nm‐sized seed particles are reported. The 0.5 µm thick membrane shows a separation selectivity of 400 for CO2–CH4 mixtures and CO2 permeance of 25 × 10‐7 mol m‐2 s‐1 Pa‐1 at 20 °C and 1 bar, leading to a record‐high performance among all reported DDR membranes. Furthermore, the seed nanoparticles are grown into mono‐dispersed DDR sub‐micron crystals with trigonal and tabular habits. These crystals are assembled in monolayers for the growth of ultrathin and uniformly (h0h)‐oriented and c‐oriented films with maximum surface pore diameter of 0.365 and 0.263 nm, respectively, by using the 1‐adamantanamine template in fluoride medium. The novel strategy not only provides high‐performance membrane candidates for industrial CO2 separation, but also inspires interfacial engineering, pore size, and orientation controlling for other microporous crystals, and their membranes. [ABSTRACT FROM AUTHOR]

In this study, DDR membranes with a layer thickness of approximately 700 nm were studied for separation feeds comprising mixtures of CO 2 and CH 4. The membranes displayed the highest CO 2 over CH 4 permselectivity and CO 2 permeability reported in literature. This was ascribed to a defect-free and ultra-thin zeolite film as well as an open and highly permeable support. For equimolar mixtures, the highest CO 2 over CH 4 permselectivity of 727 was observed when the pressure at the feed side was 5 bar(a) and the permeate pressure was 1 bar(a) at 25 °C. At these conditions, the CO 2 permeability was very high at 45 × 10−7 mol/(m2 s Pa). Separation experiments for 80/20 and 20/80 mixtures were also performed, and in these cases, CO 2 over CH 4 permselectivities of 1011 and 622 were observed, respectively. For all feeds, the membrane permselectivity decreased slightly at higher temperature and in all cases, higher permselectivity was observed when vacuum was applied at the permeate side. One-stage membrane processes for upgrading biogas to biomethane at three different operating pressures were designed based on the experimental data. In all cases, a quite low membrane area, methane slip and power need were observed. [Display omitted] • DDR membranes with ultrahigh CO 2 permeance for CO 2 /CH 4 separation. • One-stage DDR membrane processes for biogas upgrading. • Low membrane area, CH 4 slip, and power use for these processes. [ABSTRACT FROM AUTHOR]

The adsorption and mass transport of CO 2 and CH 4 in CHA zeolite were studied experimentally. First, large and well-defined CHA crystals with varying Si/Al ratios and morphologies ideal for adsorption studies were prepared. Then, adsorption isotherms were measured, and adsorption parameters were estimated from the data. In the next step, permeation experiments for pure components and mixtures were conducted for a defect-free CHA membrane with a Si/Al ratio of 80 and a thickness of 600 nm over a wide temperature range. A maximum selectivity of 243 in combination with a CO 2 permeance of 70 × 10−7 mol/(m2 s Pa) was observed for a feed of an equimolar CO 2 /CH 4 mixture at 273 K and 5.5 bar. Finally, a simple model accounting for adsorption and diffusion through the surface barriers and the interior of the pores of the membrane was fitted to the permeation data. The fitted model indicated that the surface barrier was a surface diffusion process at the pore mouth with higher activation energy than the diffusion process within the pores. The model also showed that the highly selective mass transport in the membrane was mostly a result of a selective surface barrier and, to a lesser extent, a result of adsorption selectivity. [Display omitted] • CHA crystals with various Si/Al ratios were studied for gas adsorption. • The adsorption were performed in a wide temperature range of 150–350 K. • Single gas and CO 2 /CH 4 permeation were measured over an ultra-thin CHA membrane. • Adsorption parameters were used to model mass transport through the CHA membrane. • High CO 2 /CH 4 selectivity is mostly due to high surface permeability selectivity. [ABSTRACT FROM AUTHOR]

In the present work, single channel tubular zeolite CHA membranes with a length of 50 cm and a membrane area of 100 cm2 were evaluated by SEM and permeation experiments with single components and industrially relevant humid mixtures. The membranes comprised well-intergrown and smooth CHA films with a thickness of <500 nm supported on the inside of a highly porous tube. For single component permeation, a very low SF 6 permeance of 4.5 × 10−10 mol/(m2‧s‧Pa) was observed, which indicated nearly defect free membranes. On the contrary, the membranes displayed a very high CO 2 permeance of 128 × 10−7 mol/(m2‧s‧Pa), which illustrated the very high permeability of the CHA pores. Finally, the membranes displayed excellent selectivity for separation of industrially relevant CO 2 /CH 4 /H 2 O mixtures, which was attributed to selective interaction between the CO 2 molecules and the polar water molecules in the pores. The highest observed CO 2 /CH 4 separation selectivity was as high as 198 in combination with a CO 2 permeance of 14 × 10−7 mol/(m2‧s‧Pa) at a feed pressure of 600 kPa (including 2.2 kPa water) and 293K. The corresponding CO 2 flux was 0.39 mol/(m2‧s) and the corresponding CO 2 /CH 4 separation factor was 162. The observed membrane performance was reduced by concentration polarisation due to the limited feed flow in the experimental setup. The corresponding selectivity and CO 2 permeance corrected for concentration polarisation were as high as 236 and 16 × 10−7 mol/(m2‧s‧Pa), and the corrected CO 2 flux was 0.44 mol/(m2‧s) and corrected separation factor was 198. An estimate showed that even at a low feed pressure of 500 kPa, it would be sufficient with as few as 64 membranes for processing of a feed of 100 Nm3/h raw biogas, i.e. the capacity of a typical biogas plant at a large farm, to biomethane with high purity. These results illustrated that the membranes are promising candidates for industrial separation of CO 2 from e.g. natural gas and biogas. [Display omitted] • The first report described industrially relevant CHA membranes. • The membrane was a single channel tube with a membrane area of 100 cm2. • CO 2 single gas permeances was as high as 128 × 10−7 mol/(m2‧s‧Pa). • The highest observed CO 2 /CH 4 separation factor was 169. • Effect of concentration polarisation on separation was discussed. [ABSTRACT FROM AUTHOR]

Synthesis of formate from hydrogenation of carbon dioxide (CO2) is an atom‐economic reaction but is confronted with challenges in developing high‐performance non‐precious metal catalysts for application of the process. Herein, we report a highly durable edge‐rich molybdenum disulfide (MoS2) catalyst for CO2 hydrogenation to formate at 200 °C, which delivers a high selectivity of over 99 % with a superior turnover frequency of 780.7 h−1 surpassing those of previously reported non‐precious metal catalysts. Multiple experimental characterization techniques combined with theoretical calculations reveal that sulfur vacancies at MoS2 edges are the active sites and the selective production of formate is enabled via a completely new water‐mediated hydrogenation mechanism, in which surface OH* and H* species in dynamic equilibrium with water serve as moderate hydrogenating agents for CO2 with residual O* reduced by hydrogen. This study provides a new route for developing low‐cost high‐performance catalysts for CO2 hydrogenation to formate. [ABSTRACT FROM AUTHOR]

Synthesis of formate from hydrogenation of carbon dioxide (CO2) is an atom‐economic reaction but is confronted with challenges in developing high‐performance non‐precious metal catalysts for application of the process. Herein, we report a highly durable edge‐rich molybdenum disulfide (MoS2) catalyst for CO2 hydrogenation to formate at 200 °C, which delivers a high selectivity of over 99 % with a superior turnover frequency of 780.7 h−1 surpassing those of previously reported non‐precious metal catalysts. Multiple experimental characterization techniques combined with theoretical calculations reveal that sulfur vacancies at MoS2 edges are the active sites and the selective production of formate is enabled via a completely new water‐mediated hydrogenation mechanism, in which surface OH* and H* species in dynamic equilibrium with water serve as moderate hydrogenating agents for CO2 with residual O* reduced by hydrogen. This study provides a new route for developing low‐cost high‐performance catalysts for CO2 hydrogenation to formate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Based on the USPEX screening more stable SiCP 4 allotropes was obtained. • A high carrier mobility of 106 cm2 V−1 s−1 is observed for SiCP 4 allotrope. • The maximum η S T H ′ and η S T F ′ of SiCP 4 allotrope can reach 21.89% and 23.90% • Two SiCP 4 allotropes can trigger HER spontaneously. • SiCP 4 allotropes have the potential to reduce CO 2 to CH 4 or HCOOH. Two-dimensional metal-free photocatalysts are catching the attention of researchers. Here, we present several allotrope SiCP 4 monolayers with high stability, high carrier mobility, and excellent photocatalytic performance. Using a searching method based on the universal structure predictor evolutionary xtallography, together with assessing the energy and thermodynamic stabilities, and matching the potentials of band edges with the photocatalytic conditions for achieving overall water splitting, we successfully identify 5 highly favorable configurations (including the previously reported one) from a pool of 1056 allotrope SiCP 4 monolayers. The results show that the largest solar-to-hydrogen efficiency of the considered monolayers can reach 21.89 %, while a high mobility of 2.7677 × 105 cm2 V−1 s−1 is observed, both are superior to those of the previously reported one. The Gibbs free energies for hydrogen or oxygen evolutions, and CO 2 reduction reactions indicate they are thermodynamically feasible. Moreover, the hydrogen evolution reaction can proceed spontaneously with two allotrope SiCP 4 monolayers. Therefore, the newfound allotrope SiCP 4 monolayers are expected to have potential applications in the field of photocatalytic water splitting for hydrogen generation and carbon dioxide reduction. [ABSTRACT FROM AUTHOR]

Monolithic binder-free CO 2 adsorbents with high adsorption capacity, selectivity, adsorption-desorption kinetics, and regenerability are highly desired to both reduce the environmental impact of anthropogenic CO 2 emissions and purify valuable gases from CO 2. Herein, we report a strategy to prepare monolithic carbonaceous CO 2 adsorbents from low-cost and underutilized bioresources, which enabled the formation of a delicate anisotropic, hierarchical porous structure. With optimized material composition and processing conditions, the biobased carbon adsorbent demonstrated a CO 2 adsorption capacity of 4.49 mmol g-1 at 298 K and 100 kPa, relatively weak adsorbent-adsorbate affinity, good CO 2 /N 2 selectivity, and advantageous hydrophobicity against water vapor. Moreover, the unique anisotropic porous structure provided high stiffness and good flexibility to the adsorbent in the axial and radial directions, respectively. We confirmed that this type of carbon adsorbent could be packed in a column for dynamic CO 2 capture independent of any binders, indicating its promising future for further development toward widespread utilization. [Display omitted] • Biocarbon aerogels with anisotropic, hierarchical porous structure were prepared. • Carbon aerogels reached CO 2 adsorption capacity of 4.49 mmol g−1 (298 K, 100 kPa). • Carbon aerogels showed good CO 2 /N 2 selectivity and low water vapor adsorption. • Carbon aerogels exhibited strong and unique anisotropic mechanical properties. • Carbon aerogels were packed in a column without binders for large-scale CO 2 capture. [ABSTRACT FROM AUTHOR]

Keywords: Carbon Dioxide Conversion; Heterogeneous Catalysis; Materials Science; Reaction Mechanisms; Reduction EN Carbon Dioxide Conversion Heterogeneous Catalysis Materials Science Reaction Mechanisms Reduction 1 1 1 10/31/23 20231106 NES 231106 B CO SB 2 sb hydrogenation to formate b is an attractive route for the utilization of this greenhouse gas. Comprehensive mechanism studies reveal that selective production of formate is enabled at MoS SB 2 sb edge sulfur vacancies via a new water-mediated hydrogenation mechanism. Carbon Dioxide Conversion, Heterogeneous Catalysis, Materials Science, Reaction Mechanisms, Reduction. [Extracted from the article]

Keywords: Carbon Dioxide Conversion; Heterogeneous Catalysis; Materials Science; Reaction Mechanisms; Reduction EN Carbon Dioxide Conversion Heterogeneous Catalysis Materials Science Reaction Mechanisms Reduction 1 1 1 10/31/23 20231106 NES 231106 B Sn-based perovskite oxides b have shown intriguing potential in CO SB 2 sb electroreduction. Carbon Dioxide Conversion, Heterogeneous Catalysis, Materials Science, Reaction Mechanisms, Reduction In their Research Article (e202307086), Jiawei Zhu and co-workers report an effective strategy to promote CO SB 2 sb -to-HCOOH conversion of Sn-based perovskite oxides by A-site-radius-controlled Sn-O bond lengths. [Extracted from the article]

Moreover, the water-anion interactions can repel the contact of water with the active centers, thus inhibiting the occurrence of HER. The halogen anions can form hydrogen bonds with intermediates (*COOH) and thus lower the energy barrier to the formation of CO. Keywords: CO; CO2 Electrocatalysis; Covalent Organic Framework; Hydrogen Bond; Imidazolium EN CO CO2 Electrocatalysis Covalent Organic Framework Hydrogen Bond Imidazolium 1 1 1 02/07/23 20230206 NES 230206 B A hydrogen bonding strategy b for achieving an excellent electrocatalytic CO SB 2 sb reduction reaction performance over an imidazolium-functionalized covalent organic framework (Co-iBFBim-COF-X) is reported by Yuan-Biao Huang and co-workers in their Research Article (e202215687). [Extracted from the article]

In the present work, a biosynthesis route for the preparation of hierarchical pompon-like SAPO-34 was developed. Commercially available bacterial cellulose aerogel was used as template. SiO 2 loaded bacterial cellulose aerogel was used as silica source and a simple hydrothermal treatment was used for crystallization. XRD, FT-IR, SEM, TEM, N 2 adsorption-desorption and TG techniques were employed to characterize the obtained samples. The hierarchical pompon-like SAPO-34 showed a spherical morphology that was comprised of nanosheets with a thickness less than 30 nm. The specific surface area of the hierarchical pompon-like SAPO-34 was 498 m2/g that was higher than the trigonal SAPO-34 crystals of 465 m2/g. The ultrasonic treatment experiment indicated a high stability of the pompon-like structure. In addition, the hierarchical pompon-like SAPO-34 exhibited a CO 2 adsorption capacity of 2.26 mmol/g at 100 kPa and 298K and the corresponding CO 2 /CH 4 ideal separation factor was 5.7, which was higher than that of trigonal SAPO-34 crystals. The saturated adsorption capacity and b-value were estimated using single site Langmuir, Toth and Sips adsorption isotherm models and the observed results were constant. Compared with trigonal SAPO-34, hierarchical pompon-like SAPO-34 displayed a higher saturated adsorption capacity, but a lower b-value. [Display omitted] • A biosynthesis route was developed for the synthesis of hierarchical SAPO-34. • Economical bacterial cellulose aerogel was used as the template. • The hierarchical SAPO-34 crystals were comprised of ultrathin zeolite nanosheets. • A higher surface area and a higher CO 2 adsorption capacity were observed. [ABSTRACT FROM AUTHOR]

This study developed a green and efficient process for simultaneous extraction and enrichment of phytochemicals from plant waste using a novel CO 2 - responsive surfactant (CRS) aqueous with ultrasound assistance. This extraction process was optimized. using single-factor experiments combined with Box-Behnken design. The tris (2-hydroxyethyl) ammonium palmitate (THAP) aqueous was selected as extraction solvent. The optimal conditions were ultrasound time of 120 min, R(S/L) of 20 mg/mL and CRS concentration of 54 mmol/L, the extraction yields for target compounds increased 1.1 folds to 5 folds compared with other surfactants. The results showed that THAP could be guaranteed at least 5 cycles with relatively stable extraction yields of target compounds. Moreover, the mechanism study using density functional theory was applied to investigate physicochemical properties of THAP and extraction mechanism. The presented method is a promising, nontoxic, lower-cost, and sustainable alternative to extract and enrich valuable components from plant materials. [Display omitted] • The CO 2 -responsive surfactant- aqueous (CRS) is environmentally friendly. • The CRS as an alternative is used for extraction components from Cili leaves. • The mechanism study investigated the CRS the solubilization characters. [ABSTRACT FROM AUTHOR]