Sorption Enhanced Water Gas Shift Research Articles

Integration of dry-reforming and sorption-enhanced water gas shift reactions for the efficient production of high-purity hydrogen from anthropogenic greenhouse gases

With growing interest in the bulk production of the alternative energy carrier hydrogen, dry-reforming of methane using carbon dioxide has attracted great interest as one of the possible carbon capture and utilization (CCU) technologies and hydrogen production methods. An integrated system combining the dry-reforming and water gas shift reactions is suggested to improve the productivity of hydrogen, and a system has also been developed for high-purity hydrogen production from a single system using the sorption-enhanced reaction concept. To realize the proposed system, we develop the Ru-doped Sr0.92Y0.08TiO3 perovskite catalysts and investigate their characteristics using various analyses. The prepared catalysts exhibit excellent CH4 conversion of 92.2% for the dry-reforming reactions at 800 °C without performance degradation by coke formation. Moreover, high-purity hydrogen (>99.5%) is directly produced by the proposed integrated system using anthropogenic greenhouse gases as reactants, and the efficiency is further enhanced by recycling the captured CO2 to the dry-reforming reactor.

Assessment of CO2 capture efficiency in packed bed versus 3D-printed monolith reactors for SEWGS using CFD modeling

Sorption Enhanced Water-Gas Shift (SEWGS) couples the water gas-shift reaction with CO2 adsorption on potassium-promoted hydrotalcite (K-HTC) sorbent material for hydrogen production and CO2 capture. Here, computational fluid dynamics (CFD) models are developed to simulate the adsorption step in SEWGS considering both packed bed and monolith reactors. The goal of this research is increasing SEWGS productivity by using 3D-printed structured bed reactors, as opposed to conventional packed bed reactors, due to the well-known advantages of monoliths, such as less mass transfer limitations and lower pressure drops. The paper presents numerical modeling and simulation work supported by experimental validation in order to compare packed bed and monolith reactors with respect to SEWGS performance. The packed bed multiscale CFD model is validated using breakthrough experimental data. A bench-scale CFD structured bed model is developed and validated based on breakthrough measurements performed by TNO using 3D-printed K-HTC monolith structures. Furthermore, geometry effects on mass transfer efficiency are investigated through CFD modeling for the bench-scale reactor. A scale-up of the monolith model to pilot-scale allows for a proper comparison with the packed bed technology. Monolith reactor model breakthrough predictions show there is a considerable increase in mass transfer rate over the packed bed reactor for the adsorption step in SEWGS, demonstrating promising potential towards enhancing the carbon capture technology.

Health Risk and Environmental Assessment of Cement Production in Nigeria

The cement manufacturing industry has played a fundamental role in global economic development, but its production is a major facilitator to anthropogenic CO2 release and solid waste generation. Nigeria has the largest cement industry in West Africa, with an aggregate capacity of 58.9 million metric tonnes (MMT) per year. The Ministry for Mines and Steel Development asserts that the nation possesses total limestone deposits of around 2.3 trillion MT with 568 MMT standing as established reserves and 11 MMT used. Cement industries are largely responsible for releasing air pollutants and effluents into water bodies with apparent water quality deterioration over the years. Air pollution from lime and cement-producing plants is seen as a severe instigator of occupational health hazards and work-related life threats, negatively affecting crop yields, buildings, and persons residing in the vicinity of these industries. World Bank observed in 2015 that 94% of the Nigerian populace is susceptible to air pollutants that surpass WHO guidelines. In 2017, World Bank further reported that 49,100 premature deaths emanated from atmospheric PM2.5, with children beneath age 5 having the greatest vulnerability owing to lower respiratory infections, thereby representing approximately 60% of overall PM2.5-induced deaths. Cement manufacturing involves the significant production of SO2, NOx, and CO connected to adverse health effects on humans. Sensitive populations such as infants, the aged, and persons having underlying respiratory ailments like asthmatics, emphysema, or bronchitis are seen to be most affected. Consequently, in addressing this challenge, growing interests in enacting carbon capture, usage, and storage in the cement industry is expected to alleviate the negative environmental impact of cement production. Still, no carbon capture technology is yet to achieve commercialization in the cement industry. Nonetheless, huge advancement has been made in recent years with the advent of vital research in sorption-enhanced water gas shift, underground gasification combined cycle, ammonium hydroxide solution, and the microbial-induced synthesis of calcite for CO2 capture and storage, all considered sustainable and feasible in cement production.

Water gas shift and sorption-enhanced water gas shift reactions using hydrothermally synthesized novel Cu–Mg–Al hydrotalcite-based catalysts for hydrogen production

As the interest in environmentally-friendly energy processes increases, many studies have been focused on producing hydrogen as an alternative energy carrier via catalytic reaction processes. Among several potential reaction processes, water gas shift (WGS) reaction has been studied extensively as a typical catalytic reaction for bulk production of hydrogen. Recently, many studies have been conducted on the formation of an easily reducible active components in order to develop novel catalysts having excellent activities at low temperatures for WGS reaction. In this study, new catalysts based on hydrotalcite with unique interlayered structure were prepared by a hydrothermal synthesis and co-precipitation of copper (Cu) for active metal sites. The catalysts synthesized from different precursors showed that the reduction property of Cu was greatly changed according to the mixed oxide structure generated after calcination. Cu–MgHAlH, the hydrotalcite-based catalyst synthesized using hydroxide precursors, showed the highest redox property and the multiple analysis results confirmed that MgAl2O4 spinel structure is attributed to form easily reducible Cu species. Based on these characteristics, Cu–MgHAlH showed excellent catalytic performance in the WGS reactions between 250 and 400 °C, and it was successfully applied to the sorption-enhanced WGS reaction using catalyst-sorbent hybrid solid pellets. Especially, the hydrotalcite-based catalyst has high potential for application to sorption-enhanced reaction processes using molten salt containing CO2 sorbents because the high reduction properties of Cu species are well maintained in the catalyst when mixed with CO2 sorbents.

Sorption-Enhanced Water-Gas Shift Reaction for Synthesis Gas Production from Pure CO: Investigation of Sorption Parameters and Reactor Configurations

A sorption-enhanced water-gas shift (SEWGS) system providing CO2-free synthesis gas (CO + H2) for jet fuel production from pure CO was studied. The water-gas shift (WGS) reaction was catalyzed by a commercial Cu/ZnO/Al2O3 catalyst and carried out with in-situ CO2 removal on a 20 wt% potassium-promoted hydrotalcite-derived sorbent. Catalyst activity was investigated in a fixed bed tubular reactor. Different sorbent materials and treatments were characterized by CO2 chemisorption among other analysis methods to choose a suitable sorbent. Cyclic breakthrough tests in an isothermal packed bed microchannel reactor (PBMR) were performed at significantly lower modified residence times than those reported in literature. A parameter study gave an insight into the effect of pressure, adsorption feed composition, desorption conditions, as well as reactor configuration on breakthrough delay and adsorbed amount of CO2. Special attention was paid to the steam content. The significance of water during adsorption as well as desorption confirmed the existence of different adsorption sites. Various reactor packing concepts showed that the interaction of relatively fast reaction and relatively slow adsorption kinetics plays a key role in the SEWGS process design at low residence time conditions.

Modelling of CO <sub>2</sub> and H <sub>2</sub>O Interaction During Adsorption Cycles on Hydrotalcite for SEWGS Applications

Sorption Enhanced Water Gas Shift (SEWGS) is an intensified pre-combustion capture process, based on a potassium promoted Mg/Al-hydrotalcite sorbent. The technology has demonstrated low energy requirements and high capture performances in real industrial settings within the Iron and Steel sector. Reactor modelling is an essential tool to develop energy and cost-efficient SEWGS units. The TNO developed model captures the fundamentals of the gas-solid thermodynamic and kinetic interactions, to accurately predict the multi-column behaviour, allowing for unit sizing and quantification of the energy requirements. The updated interaction model consists of Langmuir interaction for CO2, a competitive interaction site for CO2 and H2O, an exchange site where either CO2 or H2O is adsorbed and a pore condensation for high-pressure H2O. The updated model is validated against single column and multi-column operation with simulated blast furnace gas.

High-purity H2 production by sorption-enhanced water gas shift on a K2CO3-promoted Cu/MgO–Al2O3 difunctional material

A sol–gel derived, K2CO3-promoted Cu/MgO–Al2O3 difunctional material that integrates catalytic and adsorptive sites can produce high-purity H2 (>99.9%) in consecutive sorption-enhanced water gas shift (SEWGS) cycles.

3d-Printing of Adsorbents for Increased Productivity in Carbon Capture Applications (3d-Caps)

The 3D-CAPS project aims to increase the productivity (kg CO2/m3hr) of adsorbent based carbon capture technologies by an order of magnitude through structuring, enabled with 3D-printing. This productivity increase would allow for a reduction of the size of the adsorbers and the associated CAPEX and/or energy requirements. pre-combustion, as well as post-combustion technologies, are investigated using potassium-promoted hydrotalcite (K-HTC) for sorption-enhanced water-gas shift (SEWGS) and aminefunctionalized silica (ImmoAmmo) as sorbent, respectively. This contribution presents a technical overview highlighting several aspects of the project ranging from CFD modelling to assess the shape of the sorbents, 3D-printing of the sorbent materials as well as testing of the ImmoAmmo sorbent for post-combustion capture applications. It is discussed how several essential elements of the productivity improvement have been separately proven in the 3D-CAPS project, both by modelling and experimentally: maintained adsorption capacity upon 3D-printing, reduced drop reduction, and improved mass transfer .

Performance and dynamic behavior of sorption-enhanced water-gas shift reaction in a fluidized bed reactor for H2 production and CO2 capture

A multi-scale dynamic model for a sorption-enhanced water-gas shift (SE-WGS) fluidized bed reactor was developed and the reactor performance in terms of hydrogen production and carbon dioxide capture was analyzed. K2CO3-promoted hydrotalcite sorbent was used as a reference in the SE-WGS fluidized bed reactor and steam methane reforming gas was used as the feed. The sensitivity analysis of the performance was carried out by varying the temperature, pressure, and sorbent circulation rate. The CO conversion achieved at low pressures in the SE-WGS fluidized bed reactor was much higher than the catalytic equilibrium conversion. However, the advantages of the SE-WGS reactor were lost at pressures of over 7 bar. The desired sorption capacity and rate of the CO2 sorbent were suggested to enhance the performance of the SE-WGS fluidized bed reactor at 30 bar. At a five-time higher sorption capacity, the CO conversion and carbon capture efficiencies could be achieved to 95.0% and 86.4%, respectively. In addition, with a simultaneous increase of 1.5 times in the sorption rate, the CO conversion and carbon capture efficiency could be achieved to 99.3% and 98.2%, respectively. Because the CO2 sorption capacity is mainly determined in the mixing zone, the operating conditions need to be finely controlled for the maximum utilization of the sorbent capacity. The study demonstrates the advantages of the SE-WGS fluidized bed reactor for simultaneous H2 production and CO2 capture. In addition, the optimization of the sorption capacity and rate of the CO2 sorbent can provide guidance for the development of high-performance sorbents for application in SE-WGS fluidized bed reactors.

Synthesis and Evaluation of K-Promoted Co3-xMgxAl-Oxides as Solid CO2 Sorbents in the Sorption-Enhanced Water−Gas Shift (SEWGS) Reaction

Hydrogen is essential in a variety of large-scale chemical processes. As a carbon-free energy carrier, hydrogen has a potential for wide use within power production and transportation. However, mos...

Environmental benefits of urea production from basic oxygen furnace gas

Basic oxygen furnace gas (BOFG) is a multi-component residual flow from integrated steel mills composed of CO, CO2, O2, N2 and H2. In this study, we use the life cycle assessment method to quantify the environmental impacts of six applications of BOFG: heat for internal use in the steel mill, heat combined with CO2 storage, electricity production, urea production, urea production combined with CO2 storage and flaring. Urea can be produced from solely BOFG components, making use of the sorption enhanced water–gas shift technology. This application of BOFG is described here for the first time. The environmental impacts of these six applications were compared in light of the impacts of their conventional production (‘counterfactual’). Using BOFG for the production of electricity and urea would result in net greenhouse gas emissions of 0.87 tCO2-eq/tBOFG and 0.69 tCO2-eq/tBOFG, respectively. When excess CO2 is transported and stored, net emission savings could be achieved when producing urea (−0.11 tCO2-eq/tBOFG) and heat (−0.12 tCO2-eq/tBOFG) from BOFG, again as compared to their counterfactual of conventional production. Overall environmental impacts were slightly lower for electricity (5.2E−4 DALY/tBOFG, 1.9E−6 species.yr/tBOFG) compared to urea (6.2E−4 DALY/tBOFG, 1.9E−6 species.yr/tBOFG). Sensitivity analysis showed, however, that when replacing cleaner electricity (e.g. under future power decarbonisation), these relative environmental benefits of electricity production from BOFG are diminished. We conclude that urea production, rather than the current practice of electricity production, is the best investigated option to reduce environmental impacts of BOFG, which can lead to net environmental benefits when combined with CO2 storage.

CO2 utilization for combined gasification and sorption enhanced water-gas shift for syngas production of biochar

Searching for alternative renewable energy to serve high demand of energy consumption has been of interest for decades. However, the production of energy comes with an emission of large amount of CO2, the main cause of global warming problem. As a consequence, improvement of energy production process in terms of increasing high efficiency and reducing CO2 emission are required [1]. This research verified the combined systems: biochar gasification and sorption-enhanced water gas shift reaction for the production of synthesis gas. The effect of calcium precursor on CaO-based sorbents, type of metal on multifunctional materials, and amount of co-feed CO2 as gasifying agent on process performances were focused on this work. Fixed-bed reactors were used for both gasification and sorption-enhanced water-gas shift experiments. Performances of the system were analyzed in terms of %biochar conversion, H2/CO ratio, and CO2 emission. The temperature used in the gasification process was fixed at 900°C and sorption-enhanced water-gas shift was 600°C at 1 atm. The results showed the sorbent CaO/Caj2Alj4O33 derived from calcium nitrate displayed the best performance for CO2 capture, whose CO2 capture capacity is 0.34 gCO2/g sorbent at 30%CO2v/v at 600°C. For the combined gasification and sorption-enhanced water-gas shift reaction, 98% biochar conversion can be obtained. Ni/CaO-Caj2Ali4O33 offered higher H2/CO ratio and CO2 emission when compared to Cu/CaO-Ca12Al14O33 at fixed feed molar ratio of H2O:CO2:O2:C = 0.5:0.5:0.125:1. The utilization of CO2 as gasifying agent at feed molar ratio of H2O:CO2:O2:C = 0.5:0.1:0.125:1 demonstrated the reduction of CO2 emission with the production of H2/CO ratio = 0.23.

MODELING OF A RECTANGULAR CHANNEL MONOLITH REACTOR FOR SORPTION-ENHANCED WATER-GAS SHIFT

As CO2 concentration levels in the atmosphere are steadily reaching a point of no return, it is paramount that actions are taken towards mitigating emissions by improving the efficiency of existing processes. Sorption-enhanced water-gas shift (SEWGS) combines the water-gas shift reaction with in-situ adsorption of CO2 on potassium-promoted hydrotalcite (K-HTC). This enables a direct conversion of syngas into separate hot streams of H2 at feed pressure and CO2 at regeneration pressure, making the process attractive for pre-combustion carbon capture and storage (CCS) and reduction of greenhouse gas emissions. The current work is evaluating the high-temperature, high-pressure adsorption step of the SEWGS process enhanced by a novel technology which replaces common packed bed reactors with 3D-printed monolithic structures. This approach would enable an overall increase in process productivity. To this extent, innovative dynamic models based on validated competitive adsorption isotherms were developed in this work. COMSOL Multiphysics was used to develop a 1D computational fluid dynamics (CFD) model of adsorption for a fixed bed reactor in order to verify the model accuracy against existing studies. Subsequently, 2D CFD simulations were developed to describe adsorption inside monolith structures, both free and porous regions. The multi-component adsorption isotherm used in the simulations was validated with published breakthrough capacities for CO2 and H2O at different pressures. Model predictions are in agreement with expected behavior, as monolith reactors provide a more efficient mass transfer, and will be used to enhance the performance of experimental monolith structures used in SEWGS.

Development of an effective bi-functional Ni–CaO catalyst-sorbent for the sorption-enhanced water gas shift reaction through structural optimization and the controlled deposition of a stabilizer by atomic layer deposition

Bi-functional Ni–hollow CaO stabilized by ALD-grown Al2O3 overcoat for sorption-enhanced water-gas shift reaction producing high purity hydrogen.

Techno-economic assessment of SEWGS technology when applied to integrated steel-plant for CO2 emission mitigation

Mitigation of CO2 emissions in the industrial sector is one of the main climate challenges for the coming decades. This work, carried out within the STEPWISE H2020 project, performs a preliminary techno-economic assessment of the Sorption Enhanced Water Gas Shift (SEWGS) technology when integrated into the iron and steel plant to mitigate CO2 emissions. The SEWGS separates the CO2 from the iron and steel off-gases with residual energy content (i.e. Blast Furnace Gas, Basic Oxygen Furnace Gas and Coke Oven Gas) and the produced H2 is sent to the power generation section to produce the electricity required by the steel plant, while the CO2 is compressed and transported for storage. Detailed mass and energy balances are performed together with a SEWGS cost estimation to assess the energy penalty and additional costs related to CO2 capture. Results demonstrates the potential of SEWGS to capture over 80 % of CO2 in the off-gases, which results in entire plant CO2 emission reduction of 40 % with a Specific Energy Consumptions for CO2 Avoided (SPECCA) around 1.9 MJ/kgCO2. SEWGS outperforms a commercial amine scrubbing technology which has a SPECCA of 2.5 MJ/kgCO2 and only 20 % of CO2 avoided. The cost of CO2 avoided calculated on the basis of a fully integrated steel plant is around 33 €/tCO2 compared to 38 €/tCO2 of the amine technology.

Study on critical technologies and development routes of coal-based hydrogen energy

Abstract Hydrogen is considered a secondary source of energy, commonly referred to as an energy carrier. It has the highest energy content when compared to other common fuels by weight, having great potential for further development. Hydrogen can be produced from various domestic resources but, based on the fossil resource conditions in China, coal-based hydrogen energy is considered to be the most valuable, because it is not only an effective way to develop clean energy, but also a proactive exploration of the clean usage of traditional coal resources. In this article, the sorption-enhanced water–gas shift technology in the coal-to-hydrogen section and the hydrogen-storage and transport technology with liquid aromatics are introduced and basic mechanisms, technical advantages, latest progress and future R&D focuses of hydrogen-production and storage processes are listed and discussed. As a conclusion, after considering the development frame and the business characteristics of CHN Energy Group, a conceptual architecture for developing coal-based hydrogen energy and the corresponding supply chain, is proposed.

Syngas Production from Combined Steam Gasification of Biochar and a Sorption-Enhanced Water–Gas Shift Reaction with the Utilization of CO2

This research aims at evaluating the performance of a combined system of biochar gasification and a sorption-enhanced water–gas shift reaction (SEWGS) for synthesis gas production. The effects of mangrove-derived biochar gasification temperature, pattern of combined gasification and SEWGS, amount of steam and CO2 added as gasifying agent, and SEWGS temperature were studied in this work. The performances of the combined process were examined in terms of biochar conversion, gaseous product composition, and CO2 emission. The results revealed that the hybrid SEWGS using one-body multi-functional material offered a greater amount of H2 with a similar amount of CO2 emissions when compared with separated sorbent/catalyst material. The gasification temperature of 900 °C provided the highest biochar conversion of ca. 98.7%. Synthesis gas production was found to depend upon the amount of water and CO2 added and SEWGS temperature. Higher amounts of H2 were observed when increasing the amount of water and the temperature of the SEWGS system.

Sorption Enhanced Water Gas Shift for H2 production using sour gases as feedstock

Even though hydrogen is considered the future of energy carrier, it is still produced from fossil fuels therefore with no benefits for the CO2 emission reduction. This paper discusses an innovative concept for hydrogen production which combines the Acid Gas to Syngas (AG2S™) concept and the Sorption Enhanced Water Gas Shift (SEWGS) process. The AG2S™ process produces H2 and elemental Sulfur from H2S and CO2, then H2 purification is performed through amine scrubbing. The SEWGS technology is a Pressure Swing Adsorption process where the CO2 and H2S are adsorbed on hydrotalcite-based material. With respect to amine scrubbing, SEWGS takes advantage of a higher operating temperature of 350°C–400 °C which reduces temperature swing losses, lower regeneration energy and the possibility to recycle the H2S while capturing the CO2. This study aims at exploring the potential of the SEWGS technology by means of the evaluation of detailed mass and energy balances, showing the potentialities of the AG2S™+SEWGS technologies which more than double the H2 production efficiency (25.0%) with respect to the amine scrubbing configuration (10.7%). Including the steam production, the overall process efficiency can be higher than 90% which is again more than twice the value of the AG2S™ reference case.

Exfoliated Ni-Al LDH 2D nanosheets for intermediate temperature CO2 capture.

CO2 capture is projected as one of the pragmatic approaches to deal with the global warming phenomenon. Adsorption-based CO2 capture is considered an economically attractive option to reduce CO2 emission. The success of the adsorption-based capture primarily relies on adsorbents and thus a variety of adsorbents have been investigated in the literature. We here report a high surface area (210.2 m2/g) exfoliated Ni-Al LDH nanoplatelet as a promising candidate for CO2 capture at an intermediate temperature of 200 °C applicable to integrated gasification combined cycle (IGCC) and sorption enhanced water gas shift (SEWGS) reactions. The materials were well characterized by PXRD, TGA, FTIR, TEM, ICP-OES, and N2 adsorption surface area, and pore size distribution techniques. A unique nanoflower morphology comprising of exfoliated LDH platelets of ca. 5 layer thickness was obtained. The CO2 capture capacity (0.66 mmol/g) of the exfoliated Ni-Al LDH nanoplatelet is comparable to that of the widely reported Mg-Al LDH-derived mixed oxides and MgO-based adsorbents. Provided that Ni-Al and other transition metal LDH materials are known to exhibit superior catalytic properties for CO2 methanation, this work could pave the way for development of dual-functional materials for CO2 capture and conversion.

Life Cycle Assessment of SEWGS Technology Applied to Integrated Steel Plants

The environmental evaluation of the sorption-enhanced water–gas shift (SEWGS) process to be used for the decarbonization of an integrated steel mill through life cycle assessment (LCA) is the subject of the present paper. This work is carried out within the STEPWISE H2020 project (grant agreement No. 640769). LCA calculations were based on material and energy balances derived from experimental activities, modeling activities, and literature data. Wide system boundaries containing various upstream and downstream processes as well as the main integrated steel mill are drawn for the system under study. The environmental indicators of the SEWGS process are compared to another carbon capture and storage (CCS) technology applied to the iron and steel industry (e.g., gas–liquid absorption using MEA). The reduction of greenhouse gas emissions for SEWGS technology is about 40%. For the other impact indicators, there is an increase in the SEWGS technology (in the range of 7.23% to 72.77%), which is mainly due to the sorbent production and transportation processes. Nevertheless, when compared with the post-combustion capture technology, based on gas–liquid absorption, from an environmental point of view, SEWGS performs significantly better, having impact factor values closer to the no-capture integrated steel mill.