Search Results (5)

The increasing concentration of carbon dioxide (CO₂) in the atmosphere is a significant contributor to global warming and climate change. Effective CO₂ capture and storage technologies are critical to mitigating these impacts. This review explores various materials used for CO₂ capture, focusing on the latest advancements and their applications. The review categorizes these materials into chemical and physical absorbents, highlighting their unique properties, advantages, and limitations. Chemical absorbents, such as amine-based solutions and hydroxides, have been widely used due to their high CO₂ absorption capacities and established technological frameworks. However, they often suffer from high energy requirements for regeneration and potential degradation over time. Recent developments in ionic liquids (ILs) and polymeric ionic liquids (PILs) offer promising alternatives, providing tunable properties and lower regeneration energy. Physical absorbents, including advanced solvents like nanofluids and ionic liquids as well as industrial processes like selexol, rectisol, and purisol, demonstrate enhanced CO₂ capture efficiency under various conditions. Additionally, adsorbents like activated carbon, zeolites, metal-organic frameworks (MOFs), carbon nanotubes (CNTs), and layered double hydroxides (LDHs) play a crucial role by providing high surface areas and selective CO₂ capture through physical or chemical interactions. This paper summarizes the state of research on different materials and discusses their advantages and limitations while being used in CO₂ capture technologies. This review also discussed multiple studies examining the use of catalysts and absorption mechanisms in combination with different sorbents, focusing on how these approaches enhance the efficiency of absorption and desorption processes. Through a comprehensive analysis, this review aims to provide valuable insights into the type of materials that are most suitable for CO₂ capture and also provides directions for future research in this area. Full article

This study presents design considerations and an evaluation of a full-scale process chain for methanol and advanced drop-in fuel production derived from lignite/solid recovered fuel (SRF) feedstock. The plant concept consists of a high-temperature Winkler (HTW) gasifier coupled with an air separation unit (ASU), which provides a high-purity (99.55%) gasification oxidant agent. The concept includes the commercially proven acid gas removal (AGR) system based on cold methanol (e.g., Rectisol^® process) for the removal of BTX and naphthalene components. With the involvement of Rectisol^®, an almost pure CO₂ off-gas stream is generated that can be further stored or utilized (CCS/CCU), and a smaller CO₂ stream containing H₂S is recovered and subsequently driven to the sulfur recovery unit (e.g., Claus process). One of the potential uses of methanol is considered, and a methanol upgrading unit is implemented. The overall integrated process model was developed in the commercial software Aspen Plus^TM. Simulations for different feedstock ratios were investigated, ensuring the concept’s adaptability in each case without major changes. A number of parametric studies were performed concerning (a) the oxygen purity and (b) the reformer type, and a comparison against alternative methanol production routes was conducted. Simulations show that the proposed system is able to retain the cold gas efficiency (CGE) in the range of 79–81.1% and the energetic fuel efficiency (EFE) at around 51%. An efficient conversion of approximately 99.5% of the carbon that enters the gasifiers is accomplished, with around 45% of carbon being captured in the form of pure CO₂. Finally, the metrics of EFE and total C for the conversion of methanol to liquid fuels were 40.7% and 32%, respectively, revealing that the proposed pathway is an effective alternative for methanol valorization. Full article

The coal to ethylene glycol (CTEG) process has drawn much attention due to the serious conflict between supply and demand of ethylene glycol in China. However, it is inevitably accompanied by the problem of high CO₂ emissions. Carbon capture is one of the most promising potential effective ways to address this issue. However, the CTEG process, integrated with carbon capture technology, will lead to energy and economic penalties. Thus, a comprehensive evaluation of CTEG process with different CO₂ capture technologies is urgently needed. This study analyzed the technoeconomic performance of four CO₂ capture alternatives for the CTEG process: Rectisol, mono-ethanol amine (MEA), chilled ammonia process (CAP) and dimethyl carbonate (DMC) technologies. Results show the energy consumption of CO₂ capture of the Rectisol process is the lowest, 1.88 GJ/tCO₂, followed by the DMC process, 2.10 GJ/tCO₂, the CAP process, 3.64 GJ/tCO₂, and the MEA process, 5.20 GJ/tCO₂. The CO₂ capture cost of the Rectisol process is lowest, CNY 169.5/tCO₂, followed by the DMC process, CNY 193.2/tCO₂, the CAP process CNY 232.6/tCO₂, and the MEA process CNY 250.5/tCO₂. As the Rectisol technology has the best comprehensive performance, it is the best option for CTEG industry in comparison with the MEA, CAP, and DMC technologies. Full article

A novel process model simulating methanol production through pyrolysis oil gasification was developed, validated, then used to predict the effect of operating conditions on methanol production yield. The model comprised gasification, syngas post-treatment, and methanol synthesis units. The model was validated using experimental data from the literature, and the results obtained by the model were consistent with reference data. The simulation results revealed that gasification temperature has a significant impact on syngas composition. Indeed, rising temperature from 400 °C to 600 °C leads to higher syngas stoichiometric number (SN) value. Conversely, SN value decreases when the gasifier temperature is above 1000 °C. Moisture content in pyrolysis oil also affects both syngas composition and SN value; an increase in the first (from 10 to 30%) leads to an increase in SN value. The Rectisol unit deeply influences the syngas SN value and methanol yield, the best results being obtained with operating conditions of −20 °C and 40 bar. Increasing the operating temperature of the methanol synthesis unit from 150 °C to 250 °C leads to an increase in the yield of methanol production; the yield decreases beyond 250 °C. Although high pressures favor the methanol production yield, the operating pressure in the synthesis unit is limited at 50 bar for practical considerations (e.g., equipment price, equipment requirements, or operational risks). Full article

Natural gas is becoming increasingly important as a primary energy source. A suitable replacement for fossil natural gas is bio-SNG, produced by biomass gasification, followed by methanation. A major challenge is efficient gas cleaning processes for removal of sulfur compounds and other impurities. The present study focuses on development of a gas cleaning step for a product gas produced in a 50 MW_fuel gasification system. The developed gas cleaning washing process is basically a modification of the Rectisol process. Several different process configurations were evaluated using Aspen plus, including PC-SAFT for the thermodynamic modeling. The developed configuration takes advantage of only one methanol wash column, compared to two columns in a conventional Rectisol process. Results from modeling show the ability of the proposed configuration to remove impurities to a sufficiently low concentrations - almost zero concentration for H₂S, CS₂, HCl, NH₃ and HCN, and approximately 0.01 mg/Nm³ for COS. These levels are acceptable for further upgrading of the gas in a methanation process. Simultaneously, up to 92% of the original CO₂ is preserved in the final cleaned syngas stream. No process integration or economic consideration was performed within the scope of the present study, but will be investigated in future projects to improve the overall process. Full article