Journal of CO2 Utilization最新文献

Synthetic natural gas (SNG) is of great interest in reducing fossil energy consumption while maintaining compatibility with existing NG infrastructure and end-use applications equipment. SNG can be produced using clean H₂ generated from renewable or nuclear energy and CO₂ captured from stationary sources or the atmosphere. In this study, we develop an engineering process model of SNG production using Aspen Plus® and production scales reported by the industry. We examine the levelized cost and life cycle greenhouse gas (GHG) emissions of SNG production under various CO₂ supply scenarios. Considering the higher cost of H₂ transportation compared with CO₂ transportation, we assume that CO₂ feedstock is transported via pipeline to the H₂ production location, which is collocated with the SNG plant. We also evaluate the cost of CO₂ captured from the atmosphere, assuming the direct air capture process can occur near the SNG facility. Depending on the CO₂ supply chain, the levelized cost of SNG is estimated to be in the range of $45–76 per million British thermal units (MMBtu) on a higher heating value (HHV) basis. The SNG production cost may be reduced to $27–57/MMBtu-HHV by applying a tax credit available in the United States for low-carbon H₂ production (45 V). With a lower electricity price of 3ȼ/kWh for water electrolysis and accounting for a 45 V tax credit, the SNG cost reaches parity with the cost of fossil NG. Depending on the CO₂ supply chain, SNG can reduce life cycle GHG emissions by 52–88 % compared with fossil NG.

With the intensification of the global greenhouse effect, the utilization and fixation of CO₂ has become one of the most important research fields in our world. However, there are still enormous challenges in achieving efficient fixation and conversion of carbon dioxide into high-value chemicals. Herein, the cycloaddition reaction strategy is adopted to achieve the fixation of supercritical carbon dioxide (SC-CO₂) and the high-value conversion of carbon resources to propylene carbonate (PC) by using propylene oxide (PO) as the reaction precursor. Under tetrabutylammonium bromide (TBAB) as a catalyst and water (H₂O) as a green solvent, the reaction factors, such as reaction temperature, reaction pressure, catalyst amount, water concentration and molar ratio of reactants, is conducted through the high-throughput screening technology to explore the catalytic performance in a self-designed microchannel reactor. The results indicate that the yield of PC can reach 91.82 % (along with a high selectivity of 99.12 %) at a reaction temperature of 160 ℃, reaction pressure of 8 MPa, catalyst amount of 0.72 mol %, reactants molar ratio of 8, and the residence time of 482 s. Besides, the thermodynamic and kinetic for carbonate synthesis are studied to fully understand the reaction process, and the activation energy of is explored. This work is more efficient than most similar reported works, which provide valuable insights into the practical application of CO₂ in the supercritical state combined with microfluidics for synthesizing high-value monomers.

Thermochemical conversion of CO₂ in biomass gasification is a promising technology for utilizing CO₂ as a feedstock to produce a CO-rich gas. Simultaneous decomposition reactions of biomass and various gas-solid and gas-gas reactions form the product gas in this process. The overlap in sub-processes makes it challenging to assess the conversion of feedstock CO₂ with common methods like mass balancing. This work introduces stable carbon isotope ratio analysis (δ¹³C) to identify the sourcing of carbonaceous product gas components and determine the conversion of CO₂. This methodology is applied to evaluate experiments conducted for one hour of continuous operation in a lab-scale fluidized bed gasifier. Softwood pellets and wood char are used as fuel, with Olivine as a bed material, a target heating temperature of 1000 °C and atmospheric pressure. Product gas with more than 80 vol% CO was generated when wood char was used as fuel. Stable carbon isotope measurements show that CO₂ is converted at 48–93% in this process, underpinning the position of biomass CO₂ gasification as carbon capture and utilization technology. These results were up to 25% higher than suggested by mass balancing, with higher discrepancies at lower CO₂ conversions when using softwood as fuel. Therefore, stable carbon isotope ratio measurement can be a valuable tool for improving the process understanding of biomass CO₂ gasification. The results can be used for carbon accounting and the technical development of gasifiers with high CO₂ utilization efficiency.

The cycloaddition reaction of CO₂ with epoxides such as limonene epoxide (LE) to form cyclic carbonates is considered a promising alternative for reducing CO₂ emissions. In this work, CO₂ fixation on LE to produce cyclic carbonates was carried out over Zn/SBA-15 with tetrabutylammonium bromide (TBAB) as co-catalyst and over NH₃X-Zn/SBA-15 (X= Cl, Br, or I) catalysts. The catalysts were characterized by FT-IR, XRD, N₂ adsorption–desorption isotherms, TEM, NH₃-TPD, XPS, TGA and Py-FTIR. The Zn/SBA-15 support mainly presents Lewis’s acid sites of medium acidity; the surface area was 512 m²/g and 378 m²/g and the pore size were 9 nm and 7.2 nm, for Zn/SBA-15 and NH₃Cl-Zn/SBA-15, respectively. The functionalization of Zn/SBA-15 was verified by FTIR, UV-vis, and XPS analysis. It was found that when Zn/SBA-15 was used as catalyst that reaction time had a significative effect on LE conversion and in the case of limonene carbonate selectivity, co-catalyst concentration variation had the main effect. Zn/SBA-15 catalyst can be reused up to 5 times without significant changes neither in conversion nor in limonene carbonate selectivity. The best LE conversion and limonene carbonate selectivity was 33% and 93%, respectively (1 M LE, 200 mg Zn/SBA-15, 7% TBAB; 30 bar, 18 h, 700 rpm and 20 mL diethyl carbonate). The reported catalytic system is a promising system for obtaining limonene carbonate using a heterogeneous catalyst.

Artificial photosynthesis is a viable technique for mitigating the ever-increasing energy demands by converting carbon dioxide (CO₂) into energy-rich C₁ and C₂₊ products. A massive contribution to climate change and global warming is the widespread use of fossil fuels, responsible for more than 90% of total CO₂ emissions and more than 75% of global greenhouse gas emissions. The most efficient method to convert CO₂ into renewable and clean energy is utilizing plentiful sun energy to accelerate photo-induced chemical reactions. Practical CO₂ reduction (CO₂R), including choosing promising wide-bandgap (WBG) semiconductor photocatalysts with more negative conduction band potential, would be a holy grail for selective fuels and chemicals production. This review article deliberates on the importance of WBG semiconductor photocatalysts and a specific energy level in the conduction band for selective photocatalytic CO₂R, which may assist in guiding future photocatalyst design for CO₂R. In addition, the summary and prospects of WBG semiconductor photocatalysts and techniques for improving CO₂ conversion efficiency and selectivity are discussed.

The popularization of recycled concrete (RC) is an important way to achieve efficient resource utilization of construction solid waste (CSW), which can coordinate the sustainable economic development with environmental protection. In this paper, CiteSpace software is used to quantitatively analyze the literatures on RC field, identifying its research hotspots and recent developments. Based on the Web of Science database, we screened published literatures in the field of RC from 2004 to 2023, and obtained 2011 articles. CiteSpace software and knowledge graph technology are adopted to visually analyze the literature information, including the collaborators, keywords and citation status. The results show that, Xiao JZ from Tongji University, Poon CS from Hong Kong Polytechnic University and Tam VWY from University of Western Sydney publish a large number of articles and are frequently cited. It indicates that their researches are widely recognized in academic circles. There is a research team with a large size formed in the Chinese mainland, and the core members include Xiao JZ, Li WG, Chen ZP. At present, the research interest gradually shifts from recycled coarse aggregate to recycled fine aggregate, mainly focusing on microscale research of pore structure and interfacial transition zone. In addition, 8 co-citation clusters of selected references and the potential development trends are detailly analyzed. This study is helpful for researchers to fully understand the current hotspots and future research trends in the field of RC.

Seawater concrete (SWC) is an environmentally friendly construction material that addresses freshwater scarcity concerns by utilising seawater as a mixing water source. This review study comprehensively examines SWC by focusing on its fresh properties, hardened properties, seawater composition, microstructure and porosity, hydration process, durability, test methods and electrical resistivity. The study analyses the influence of additives and admixtures on SWC’s performance by considering constituents such as cement, aggregates and seawater. It also explores the impact of manufacturing techniques, including mix design. The potential of SWC is revealed and compared with that of conventional concrete by evaluating and comparing their mechanical properties, such as compressive strength, modulus of elasticity, stress-strain behaviours, tensile strength and flexural strength. This study primarily aims to thoroughly examine the characteristics of SWC in its fresh and hardened states. It also assesses the advantages and drawbacks of seawater as a mixing water source. Moreover, this study delves into the impact of seawater composition on crucial aspects, such as the hydration process, microstructure and porosity of concrete. It also used various test methods to explore SWC durability, including resistance to chloride ingress, sulphate attack and carbonation. Furthermore, the importance of electrical resistivity for corrosion prevention is discussed in this study. The carbon-negative cement production and carbonation curing of seawater concrete underscore groundbreaking advancements, emphasizing sustainability and climate mitigation in the construction industry. Overall, this study aims to enhance the comprehension of SWC and provide valuable insights for engineers, researchers and policymakers in concrete technology.

A combination of a gliding arc plasmatron (GAP) reactor and a newly designed tubular catalyst bed (N-bed) was applied to investigate the post-plasma catalytic (PPC) effect for dry reforming of methane (DRM). As comparison, a traditional plasma catalyst bed (T-bed) was also utilized. The post-plasma catalytic effect of a Ni-based mixed oxide (Ni/MO) catalyst with a thermal catalytic performance of 77% CO₂ and 86% CH₄ conversion at 700 ℃ was studied. Although applying the T-bed had little effect on plasma based CO₂ and CH₄ conversion, an increase in selectivity to H₂ was obtained with a maximum value of 89% at a distance of 2 cm. However, even when only α-Al₂O₃ packing material was used in the N-bed configuration, compared to the plasma alone and the T-bed, an increase of the CO₂ and CH₄ conversion from 53% and 53% to 69% and 69% to 83% was achieved. Addition of the Ni/MO catalyst further enhanced the DRM reaction, resulting in conversions of 79% for CO₂ and 91% for CH₄. Hence, although no insulation nor external heating was applied to the N-bed post plasma, it provides a slightly better conversion than the thermal catalytic performance with the same catalyst, while being fully electrically driven. In addition, an enhanced CO selectivity to 96% was obtained and the energy cost was reduced from ∼ 6 kJ/L (plasma alone) to 4.3 kJ/L. To our knowledge, it is the first time that a post-plasma catalytic system achieves this excellent catalytic performance for DRM without extra external heating or insulation.

Considering the flexibility in the synthesis that allows the formation of materials with more than two metals, the present study reports the preparation of trimetallic layered double hydroxides (LDHs) having Al as structural tri-positive cation, Ti as photocatalytically active d⁰ transition metal and either Ni or Co as dipositive cation. In addition, these LDHs were used as precursors of the corresponding trimetallic mixed oxides (MO). LDH and MO materials in combination with Ru(bpy)₃Cl₂ as photosensitizer and triethanolamine as sacrificial electron donor were used as catalysts for CO₂ reduction under solar light irradiation. A different product selectivity, either CH₄ for Ni-LDH or CO and H₂ for Co-MO, was observed with production rates for CH₄ or CO that are among the highest reported for these systems. The role of the inorganic materials in the photocatalytic process was supported by transient absorption spectroscopy that revealed the quenching of the Ru(bpy)₃Cl₂ triplet excited state by Ni-LDH or Co-MO. An important finding was that the trimetallic Co-Ti-Al oxide with cobaltite structure is able to perform CO₂ reduction in spite that the reduction potential of its conduction band is not sufficient to perform the process, evidence by photoluminescence revealing the existence of an upper electronic state responsible for the reduction. These results show the interest in screening multimetallic materials in photocatalysis due to their improved performance and diverse properties.

Ammonia-soda process, which produce soda ash, emits flue gas containing a large amount of CO₂ and SO_x. The wastewater discharged from the ammonia-soda process contains cations, such as Na⁺ and Ca²⁺, which can be recovered and reacted with a CO₂ and SO_x. In this study, we designed a CO₂ and SO_x utilization process for the sustainable production of sodium carbonate using wastewater recovery system, extracting Na⁺ and Ca²⁺. The proposed process involved the following steps: (1) metal-ion separation, which produces NaOH and Ca(OH)₂; (2) capture and utilization of SO_x using Ca(OH)₂; and (3) capture and utilization of CO₂ using NaOH and Ca(OH)₂, respectively. The economic feasibility of the proposed process was verified by comparing its total annualized cost (TAC) with those of conventional processes. Approximately 99% of SO_x was captured to produce high-purity desulfurized gypsum, and 99% of CO₂ was captured to be transformed into CaCO₃. To confirm the CO₂ reduction of the process, the carbon dioxide equivalent (CO₂e) was calculated by evaluating the amount of greenhouse gases. The CO₂e decreased to 71.4% compared with that of the conventional process. The TAC of the proposed process decreased by 10.67% and 19.63% compared with that of the ammonia-soda and Hou processes, respectively. Thus, this study proposes an industrially potential process design for sustainable sodium carbonate production by utilizing CO₂ and SO_x with wastewater recycling, without additional reactants, making it more economically viable.