Journal of CO2 Utilization最新文献

Extraction of cannabinoids from different parts of the plant matrix is often carried out by various traditional methods based on the use of organic solvents. Supercritical fluid extraction (SFE) has emerged as one of the most intriguing approaches for the extraction of cannabinoids. This review examines the importance of the SFE of cannabinoids, extraction parameters, selection of a suitable co-solvent/modifier, and appropriate sample preparation. To characterise the composition of the mixture of cannabinoids different analysis methods can be applied. One of them is high-performance liquid chromatography (HPLC), which requires no derivatisation of the analysed sample and allows for a determination of a wide variety of both acidic and neutral cannabinoids. Nevertheless, liquid chromatography with tandem mass spectrometry (LC-MS/MS) is gaining increasing importance due to its superior identification of analytes which is based on both the retention times of analytes as well as specific qualifier ions. Another interesting analytical method is supercritical fluid chromatography (SFC), which uses supercritical fluids (SCFs) such as CO₂ in combination with different modifiers, to successfully separate and determine cannabinoids. The use of SFC allows for an efficient and above all, rapid separation of the desired analytes. There is an essential need to efficiently investigate the influence of various experimental parameters on the retention behaviour of cannabinoids in SFC.

Blast-furnace-slag aggregate (BFSA), a by-product of the steel industry, is an eco-friendly natural, aggregate substitute used in mortar and concrete. However, research on self-healing cement composites using BFSA is rare. In this study, the compressive strength, chloride-ion-penetration resistance, and crack-recovery properties of self-healing cement mortar samples prepared using cementitious material capsules (CMC) and BFSA of different ratios were examined and compared to a control sample. The test samples were: Control; C05B00 (5 % CMC and 0 % BFSA); C05B25 (5 % CMC and 25 % BFSA); C05B50 (5 % CMC and 50 % BFSA); C10B00 (10 % CMC and 0 % BFSA); C10B25 (10 % CMC and 25 % BFSA); and C10B50 (10 % CMC and 50 % BFSA). The compressive-strength recovery rate of the control stopped increasing after 28 days and was approximately 110 % on day 56 – that of C10B50 was approximately 121 %, (∼10 % greater than that of the control) and continued to increase even after 56 d. The chloride-ion-penetration resistance of C10B50 was excellent; the 28-day total charge was approximately 5858 C (∼ 40.2 % lower than that of the control). The crack-recovery rates, on day 28, of C05B50 and C10B25 were 71 % and 70 %, respectively (∼ 29–30 % higher than that of the control).

Both indirect CO₂ hydrogenation (reverse water gas shift (RWGS) followed by CO-based Fischer-Tropsch synthesis (FTS)) and direct CO₂-based FTS were considered for CO₂ hydrogenation, and a kinetic model for the chain-length distribution of hydrocarbon products was developed. For independent estimation, the kinetic parameters were estimated by fitting the experimental data using powder catalysts under various conditions, mainly including CO/CO₂ ratios. The contribution of indirect CO₂ hydrogenation (RWGS followed by CO-FTS) was more favorable than that of direct CO₂-FTS, and CO₂ conversion and product selectivity were significantly dependent on the temperature and hydrogen fraction. The effectiveness factor was estimated for the pellet-type catalysts, and values less than one validated the existence of mass-transfer resistance. Computational fluid dynamics (CFD) modeling was used to simulate the three-dimensional thermal behaviors of a mini-pilot-scale reactor with a substantially large diameter loaded with a pellet-type catalyst and inert materials. Both a low catalyst loading in the early stage of the reactor and the use of an additional inner cooling tube showed a stable temperature profile, with the peak temperature maintained below 350 °C (the critical temperature to prevent the thermal decomposition of chemicals) and fast heating of cold feed in the early stage. The CFD results with no inner tube showed thermal runaway in the second reactor, and the simulation with arbitrarily reduced heat of the reaction (70 % of the actual value) resulted in a peak temperature higher than 410 °C. Further quantitative analysis indicated that the no-inner-tube case's reduced heat transfer area per unit volume was responsible for its thermally unstable behavior.

Electro-synthetic fuel is proposed as an approach to achieve net-zero carbon emissions for heavy-duty internal combustion engines and meet carbon neutrality targets. This method is based on high temperature co-electrolysis using a solid oxide electrolysis cell (SOEC) coupled with Fisher-Tropsch (FT) synthesis due to its high efficiency and carbon recycling capacity. To access the techno-economic viability of this pathway and identify the key elements impacting the cost of electro-synthetic fuels, a comprehensive techno-economic model is constructed. This model aims to offer cost cutting guidance and includes SOEC, FT, and techno-economic sub-models, with SOEC and FT validated using literature data. The cost breakdown and sensitivity analysis indicate that heating costs, electricity prices, and stack lifetime are critical factors in reducing the cost of electro-synthetic fuel. Three alternative system layouts that fully utilize thermal and chemical energy are proposed to address the significant heating expense issue. Among these, the optimal system design lowers costs by approximately 5.3 %. Furthermore, this work introduces the contradiction between high performance, high stability, and low-cost accounting for the SOEC lifetime, which is bounded by operating current density. When considering the degradation and replacement of SOEC stacks, the long-term profitability of operating SOEC at a current density of 500 mA/cm² is superior to that of 850 mA/cm². Despite the most effective layout being currently unprofitable, it is anticipated that in the future, carbon trade, renewable electricity and technological advancements will drive the cost of electro-synthetic fuel to become competitive with that of diesel.

The gas-phase CO₂ electroreduction to formate represents one of the most promising CO₂ conversion processes due to its scalability, as the product concentration surpasses 30 % wt. However, the use of alkaline media anolytes, intended to improve the efficiency and selectivity of formate production, causes the carbonate and bicarbonate salts to precipitate over the Gas Diffusion Electrode (GDE). This precipitation clogs the porous structure, leading to a rapid loss of electrode stability. In this work, we address this issue by proposing the use of acid anolytes, based on K₂SO₄, to mitigate the precipitation of insoluble salt on the GDE structure, thereby achieving longer and more stable GDE operation times. Various anolyte concentrations and pHs are evaluated, with 0.3 M K₂SO₄ at pH 1, adjusted using H₂SO₄, providing the best compromise. This condition inhibited potassium carbonate and bicarbonate precipitation, as observed through XRD, SEM, and EDS analysis, while maintaining high CO₂ electroreduction to formate performance, with a concentration of 69 g L⁻¹, and a Faradaic Efficiency of 33 %. Furthermore, the anolyte flowrate per geometric area is optimized to maximize the system performance. At a flowrate of 0.85 mL min⁻¹ cm⁻², enhanced concentration of 88 g L⁻¹ and a Faradaic Efficiency of 42 % are reached. Besides, long-term experiments demonstrated that GDEs used with alkaline conditions exhibit a larger deactivation constant (0.7652) compared to the GDEs used with acid anolytes (0.3891). This indicates that salt precipitation more rapidly reduces GDE performance under alkaline conditions. These results represent a promising advance in obtaining longer-lasting GDEs, which are crucial to successfully scaling up the CO₂ electroreduction to formate.

Acetate ester compounds find widespread use in various applications such as surface coatings, ink formulations, pharmaceuticals, and adhesives. It is essential to investigate the phase transition behavior of amyl acetate, amyl acetoacetate, and isoamyl acetoacetate in high-pressure supercritical CO₂ (SC-CO₂). The vapor-liquid equilibria (VLE) of the SC-CO₂ + amyl acetate, SC-CO₂ + amyl acetoacetate, and SC-CO₂ + isoamyl acetoacetate systems were examined at different temperatures (313.2 ≤ T ≤ 393.2 K) and pressures (1.67 ≤ P ≤ 20.76 MPa). The solubility curve of these systems shows Type-I phase behavior, and the critical points of these binary mixtures were observed between the critical properties of the pure components involved in the systems. The solubility of amyl acetate, amyl acetoacetate, and isoamyl acetoacetate in the SC-CO₂ + amyl acetate, SC-CO₂ + amyl acetoacetate, and SC-CO₂ + isoamyl acetoacetate systems increases with increasing temperature at constant pressure. The two-parameter model of Peng-Robinson equation of state along with a mixing rule, accurately correlated the phase transition behavior and critical mixtures curves for all three systems. The binary interaction parameters (BIPs) were adjusted, and the minimum root mean square deviation percentage was identified for all three systems. The calculated error% was found to be within reasonable limits, with values of 4.95 %, 3.93 %, and 4.18 % for SC-CO₂ + amyl acetate, SC-CO₂ + amyl acetoacetate, and SC-CO₂ + isoamyl acetoacetate systems, respectively. Furthermore, the interaction parameters for the SC-CO₂ + amyl acetoacetate mixture was found to be temperature-dependent, and the tested linear regression correlation coefficient for the BIPs parameters of (k_ij) and (η_ij) are 0.98533 and 0.99083, respectively. This is the first research study on the phase behavior of acetate ester compounds in SC-CO₂ solvents, and the results have a significant impact on industries at different operating conditions.

We synthesized a core-shell resin structure with abundant architecture and excellent thermal stability through polymerization. Imidazole ionic liquid with varying carbon chain lengths was immobilized on the surface, resulting in the preparation of metal-free, halogen-free core-shell catalysts with different carbon chain lengths via HCO_3^- exchange. Characterization using FT-IR, XPS, and various techniques revealed the exceptional performance of our synthetic catalyst in terms of its internal structure. After extensive experimentation, we discovered that the synthesized catalyst exhibits dual functionality for epoxidation and CO₂ cycloaddition reactions without requiring solvents or co-catalysts. The epoxidation system demonstrated remarkable conversion rates and selectivity while also exhibiting strong recyclability in heterogeneous reactions, according to kinetic parameters, the reaction order of styrene, TBHP and catalyst during epoxidation is approximately 1, the reference factor for this reaction was calculated to be 6.7×10⁹ (L²·mol⁻²·min⁻¹), with an activation energy of 48.9 kJ/mol obtained from analyzing reaction rates at different temperatures. In the CO₂ cycloaddition reaction, our catalyst exhibited an advantage in catalyzing ring-opening reactions, achieving a conversion rate of 95 % for styrene oxide within six hours along with over 99 % selectivity towards cyclic carbonate formation. It is suggested that the epoxide reaction is carried out in steps, and it is inferred that the catalyst PS-ImC₄HCO₃ and TBHP are produced into peroxy intermediate active species TBA and HCO₄, and the reaction between HCO_4^- and styrene is the determination step of the total reaction. The reaction rate constant k=0.009 of the absolute step is calculated based on the global optimization algorithm

We investigate the potential to reduce costs and greenhouse gas emissions of the utilization of direct air capture of CO₂ (DAC) for the production of algal biofuel. We examine four integrated designs for a DAC system comprised of solid amine monolith adsorbents delivering CO₂ at the required level for algae cultivation with a photobioreactor (PBR)-based fuel production facility. We show that the integration of DAC with this biofuel production facility provides cost and greenhouse gas emissions benefits. Heat integration decreases operating expenses by reducing energy demand for heating requirements. Mass integration, utilizing flue gas CO₂ as a carbon source for the PBRs, decreases the DAC system scale, resulting in both capital and operating cost savings. The most advantageous option depends on the interplay of heat and mass integration while matching the diurnal rhythm of algal growth with the inherently steady pace and energy requirements of the DAC system and fuel production. For these technologies, the DAC-PBR mass and energy integration provides an 18 % cost reduction and a 50 % reduction in greenhouse gas emissions for the current state of the technology.

Light olefins are critical chemical materials with high global demand. The syngas-to-olefins (STO) process offers a promising pathway for light olefin production due to the versatility of syngas production technologies from various energy sources. However, achieving high carbon monoxide (CO) conversion and selectivity for olefins remains a challenge in catalytic development. This review categorizes STO catalysts into conventional Fischer-Tropsch catalysts, including unsupported and supported metal-based catalysts (with supports such as carbon, graphene, graphene oxide, zeolites, and metal oxides), as well as bifunctional, hybrid, and emerging core@shell structured catalysts. Another type of catalyst is core@shell structure catalyst, which is a developing method widely used for FT reactions. The performance of these catalysts is influenced by their materials, chemical compositions, operating conditions, and synthesis techniques. Unsupported catalysts, especially Fe-based and Co-based, exhibit high CO conversion but face issues like rapid deactivation and complex processing requirements. Supported catalysts enhance surface area, metal dispersion, and stability, with promoters such as Na, Mg, K, Mn, Zn, V, Zr, and Cu oxides improving catalytic activity through better CO adsorption and bond modulation. Zeolites, due to their acidic properties, significantly impact reactant adsorption and activation. Catalyst preparation methods, including impregnation, co-precipitation, sol-gel, and hydrothermal synthesis, alongside post-synthesis treatments like calcination and reduction, critically affect catalyst performance. This review provides a comprehensive overview of the light olefin production from syngas, detailing the roles of various catalysts and the impact of material types, operating conditions, and synthesis techniques on catalyst activity, and selectivity. The insights aim to guide future research and development towards more efficient and sustainable light olefin production processes.

The influence of the support on catalytic activity and stability of supported 2Cr-Fe bimetallic catalysts for the CO₂-assisted dehydrogenation (DH) of n-octane has been investigated. Four MgO modified supports viz; MgO-CeO₂ (MgCe), MgO-ZrO₂ (MgZr), MgO-CeO₂-ZrO₂ (MgCeZr) and MgO-SiO₂ (MgSi) were synthesized by the sol-gel combustion technique. The supported catalysts were in turn prepared by vacuum impregnation and thereafter tested for the CO_2-assisted DH of n-octane. The catalysts were characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), N₂-physisorption, Raman spectroscopy, transmission electron microscopy (TEM), electron dispersive x-ray (EDX), temperature programmed desorption of CO₂ (CO₂-TPD), temperature programmed reduction and oxidation (H₂-TPR and CO₂-TPO), electron paramagnetic resonance (EPR) and thermal gravimetric analysis (TGA) techniques. Raman results showed that the CrO_x is stabilized as mono- and/or polynuclear Cr(VI) species over the 2Cr-Fe/MgCe catalyst, which are reduced to lower oxidation state species during the DH reaction. The 2Cr-Fe/MgZr, 2Cr-Fe/MgCeZr and 2Cr-Fe/MgSi catalysts stabilized the CrO_x as polymerized species, forming the more active Cr-O-Fe polymer units on the catalysts’ surface. XRD, TEM and EDX results showed that the ZrO₂-containing supports have smaller particles and stabilized the active metal oxides in a more dispersed amorphous state. The CO₂-TPO of the pre-reduced catalysts and EPR of the used catalysts indicated that the 2Cr-Fe/MgCeZr undergoes significant re-oxidation by CO₂ during the catalytic process. The 2Cr-Fe/MgCe was the least active, while the 2Cr-Fe/MgZr catalyst showed the best performance and stability over three regeneration cycles. Selectivity to C8 products (octenes and aromatics) was found to strongly depend on the surface basicity of the catalysts. Deactivation of the catalysts was found to follow first order kinetics and coke deposition was identified as the major cause.