Simulated Coke Oven Gas Research Articles

Hydrogen-powered enzymatic valorization using multi-enzyme co-immobilization reactor with polypeptide-based cofactor swing-arm

The chemical valorization of organic matter into high-energy products through reduction using oxidoreductase is a pivotal aspect from an energy perspective. Enzymatic valorization, utilizing the reduction potential of hydrogen contained in inexpensive resources such as coke oven gas (COG) and certain gasified plastics, enables environmentally friendly processes. Here, a strategy was proposed utilizing hydrogenase (H2ase), particularly soluble hydrogenase (SH), for selective utilization of H2 from mixtures without the separation processes. The co-immobilization of SH, elastin-like polypeptide (ELP)-based cofactor swing arm, and mannitol dehydrogenase (MDH) in a microreactor system were demonstrated for enzymatic valorization. The swing arm length and in-resin concentration were optimized to enhance electron mediation efficiency, leading to an improvement in productivity of about 3 mM/hr. Comparable productivity was observed in simulated COG and plastic waste-derived gas, which are promising results for the utilization of such low-purity H2 sources. Furthermore, the system demonstrates robustness and recyclability across maintaining productivity over 6 repeated batch reactions, highlighting its potential for industrial applications. Overall, our study provides valuable insights into the development of sustainable enzymatic microreactors for chemical valorization processes, contributing to greener and more efficient industrial practices.

Cu/ZnO/Al2O3 sorbent promoted by Zr for the ultra-deep removal of thiophene in simulated coke oven gas

The ultra-deep removal of thiophene from coke oven gas (COG) is critical for the conversion of COG to methane. Currently, Cu/ZnO/Al2O3 is considered as a promising sorbent for thiophene removal; however, its desulfurization performance is currently unable to meet the requirements for industrial applications. Here, a zirconium modification strategy is proposed to overcome this problem, allowing zirconium loaded copper-based sorbents (Cu/ZnO/Al2O3/ZrO2) with significantly improved thiophene removal performance and high activity to be obtained. Characterization results showed that zirconium improved both the dispersion of copper and the concentration of Lewis acid sites on the sorbent surface. A ZrO2 concentration of 2 % resulted in stronger Cu-Zn interaction, and the dispersion of Cu on the surface of the sorbent reached its maximum value (49.20 %). Additionally, the Lewis acid strength was also maximized, which greatly improved the desulfurization activity and resulted in a breakthrough adsorption capacity of thiophene (Qb-thiophene) of 36.24 mg/g, which was about 17 % higher than that of the unmodified Cu/ZnO/Al2O3 sorbent. These results demonstrate that the sulfur capacity of the sorbent can be increased by increasing the number of acidic sites on its surface, paving the way for ultra-deep thiophene removal in industrial applications.

Selective absorption of H2S and CO2 from simulated coke oven gas by aqueous blends of N-methyldiethanolamine and tetramethylammonium glycine

Selective absorption of H2S and CO2 from simulated coke oven gas by aqueous blends of N-methyldiethanolamine and tetramethylammonium glycine

Desulfurization mechanism of an excellent Cu/ZnO sorbent for ultra-deep removal of thiophene in simulated coke oven gas

The reactive adsorption desulfurization mechanism of thiophene over Cu/ZnO sorbent in coke oven gas (COG) was established by a combination of theoretical and experimental study. The adsorption behavior of thiophene on Cu surface was studied by density functional theory (DFT) method. The C4 hydrocarbons releases and sulfur migration over Cu/ZnO sorbent during the thiophene removal process were investigated by comparing with that over CuO, ZnO and CuO+ZnO (prepared by mechanical grinding of CuO and ZnO) sorbents. The results show that the parallel adsorption of thiophene on hexagonal closest packing (HCP) site of Cu (111) crystal face is the optimal adsorption mode. Cu0 nanoparticles in Cu/ZnO sorbent have two important roles: (1) adsorb and dissociate H2, and (2) cleave the C–S bond of thiophene. The sulfur after the cleavage of C–S bond could transfer directly to ZnO and eventually be converted into ZnS without the intermediate product CuS. During thiophene removal, C4H6 and C4H10 are generated over Cu/ZnO sorbent in the presence of H2. ZnO in Cu/ZnO sorbent not only acts as an excellent sulfur accepter, but can greatly affect the adsorption properties by enhancing the spillover and storage of hydrogen atoms. Increasing the interaction between Cu0 nanoparticles and ZnO to enhance hydrogen spillover is an effective way to improve the thiophene reactive adsorption activity of Cu/ZnO.

Metal Modified NaY Zeolite as Sorbent for the Ultra-Deep Removal of Thiophene in Simulated Coke Oven Gas

The ultra-deep removal of thiophene is essential for the conversion of coke oven gas to methane and metal modified Y zeolite has excellent thiophene adsorption capacity. The effects of temperature on chemisorption between metal modified Y zeolite and thiophene and the reductive gases in coke oven gas on the thiophene adsorption performance still remains ambiguous. To address the aforementioned aims, series of NaMY (M = Ce, Ni, Zn and Ag) were prepared via ion-exchanged with Na+ of NaY, and two comparable sets of thiophene adsorption evaluation were conducted in a fixed bed reactor: (1) NaY and NaMY were evaluated at different temperatures in simulated coke oven gas, and (2) NaCeY was evaluated in N2 and different reductive atmospheres. The results show that NaNiY, NaZnY and NaAgY could adsorb thiophene via π-complexation, however, NaCeY mainly through S-Ce bond. Π complexation becomes weak above 150 °C, and the strength of S-Ce bond varies little when the temperature rises to 250 °C. Compared with that of other sorbents, the breakthrough adsorption capacity for thiophene (Qb-thiophene) of NaAgY reaches the highest 144 mg/g at 100 °C, but decreases sharply when temperature rises to 200 °C. NaCeY has relatively low variation in Qb-thiophene from 100 °C to 200 °C. Moreover, Ce(IV) in NaCeY is more favorable for thiophene adsorption than Ce(III) in coke oven gas and the presence of H2 and CO would reduce the desulfurization activity of NaCeY. For the industrial utilization of thiophene ultra-deep removal, NaAgY has an excellent potential below 150 °C, while NaCeY with more Ce(IV) has a good prospect at 150–250 °C.

Investigation on the characteristics and kinetics of isothermal reduction of hematite under simulated coke oven gas atmosphere in rotary bed reactor

The effect of H2–CO ratio, reduction temperature and time on the reduction degree, mineral phase, and morphology of the reduced production was investigated in this study by reducing hematite with coke oven gas (COG) as the reducing agent to alleviate the pressure from the increasing demand of iron ore. The kinetics analysis, reduction mechanism, and deposited carbon behavior were proposed. The results revealed that the reduction degree reached the maximum value of 94.69% at the temperature of 900 °C for 10 min in a simulated COG atmosphere. At 800 °C, the pores and cracks on the surface of the particle became more and wider as the reaction time increased. When the reaction time reached 30 min, massive Fe3C was attached to the surface, and the newly formed spherical metallic irons were bonded to each other and randomly distributed on the surface of the product particles. Besides, the deposited carbon mainly existed in two forms of a rough porous structure and cluster structure when the temperature increased to 900 °C. The hematite reduction process was mixed-controlled by one-dimensional diffusion reaction and three-dimensional interfacial reaction, and the activation energy decreased to 50.79 kJ/mol.

Fluorine-free synthesis of all-silica STT zeolite membranes for H2/CH4 separation

Hydrogen (H2) is the most promising alternative to fossil energy for zero-emission of CO2. However, the by-produced H2 from coking process was generally burned as fuel. It is highly desired to recycle the H2 from coke oven gas as the clean energy resource. Herein all-silica STT zeolite membranes were prepared from the fluorine-free precursor for H2/CH4 separation. The crystallization period was shortened by 75% at the elevated temperature. After hydrothermal synthesis of 2 days, the membrane showed H2 permeance up to 2.8 × 10−8 mol·m−2·s−1·Pa−1 and H2/CH4 selectivity up to 49.6 at 0.2 MPa and 298 K. More importantly, STT zeolite membrane was resistant to CO and H2S, which should be prevented from feeding to the commercial polymeric and Pd membranes. The membrane was stable up to 336 h in the simulated coke oven gas of 63 H2: 28 CH4: 7 CO: 2 C2H6 containing 100 ppm H2S. This would pave the way of zeolite membranes to H2 separation in practical applications.

Co-Electrolysis of Simulated Coke Oven Gas with Carbon Dioxide Using a Solid Oxide Electrolysis Cell

A significant contributor to carbon and air-pollutant emissions is the steel industry, which is responsible for 2.8 Gt of CO2 annual emissions and accounts for a quarter of industrial CO2 emissions. A significant and valuable by-product of steelmaking is coke oven gas (COG), which is produced from coke-making via high-temperature dry distillation of coal in the absence of oxygen. COG typically consists of 55-60 vol% hydrogen (H2), 23-27 vol% methane (CH4), 5-8 vol% carbon monoxide (CO) and impurities such as H2S and tars [1]. Every ton of coke produced yields 300-360 m3 of COG and an estimated 650 Mt of COG is produced in the steelmaking industry worldwide each year, with up to 50 % re-utilised within steelmaking [2]. However, the rest is flared, contributing to carbon emissions and wasting valuable and useful gases.In this paper, co-electrolysis of simulated COG (CH4/H2 30/70 vol%) with carbon dioxide using a commercially available solid oxide fuel cell (SOFC) was investigated at 750 °C. The electrochemical performance of an anode supported button cell was characterised using open circuit potential measurements, current-voltage curves and electrochemical impedance spectroscopy. The product gas composition was analysed using quadrupole mass spectrometry (QMS).The QMS measurements show that CH4 was initially converted at the open circuit potential into synthesis gas (H2/CO) via dry reforming of CH4 and the reverse water gas shift reaction, yielding a gas mixture composed of 39.2 vol% H2, 38.3 vol% CO2, 22 vol% CO and low levels of unconverted CH4 (see figure). Increasing the voltage from the OCP to 1.4 V caused the CO2 to decrease and the CO to increase, yielding a gas mixture consisting of 42.6 vol% H2, 26.7 vol% CO2 and 29.5 vol% COincreased the synthesis gas content (H2 + CO) of the output gases by 44% relative to the OCP, with the levels of H2 produced increasing by 9% over this voltage range. In addition, the level of unconverted CH4 increased slightly, indicating that the CO2 conversion processes were competing with catalytic dry reforming of CH4. Possible reaction mechanisms are discussed. The I-V and EIS measurements established that cell electrical performance was increased by addition of CO2 through dry reforming and also improved diffusion of the fuel gases through the anode. The effects of COG fuel variability have also been investigated and show that increasing the CH4/H2 ratio from 10/90 vol% to 40/60 vol% of the COG increased the syngas production by 92%. The I-V curve and EIS measurements show that increasing the CH4/H2 ratio decreased the electrical performance of the cell due to prevalent carbon deposition. This work presents a method of efficiently utilising CO2 and suggests SOFC co-electrolysis of COG is an effective way to increase the usefulness and value of this waste gas stream.

Co-Electrolysis of Simulated Coke Oven Gas with Carbon Dioxide Using a Solid Oxide Electrolysis Cell

Coke oven gas (COG) is a byproduct of coke production typically composed of 57 vol% hydrogen, 27 vol% methane, 7 vol% carbon monoxide and impurities. It is partially re-utilised within steelmaking, with surplus flared and released to the atmosphere, significantly contributing to industrial carbon emissions and wasting a valuable resource. This study has investigated co-electrolysis of simulated COG (CH4/H2 mixtures) with a CO2 co-oxidant using a commercially available anode-supported solid oxide electrolysis cell at 750°C. The electrical performance of the cell was characterised using electrochemical techniques and the product gas composition was analysed using quadrupole mass spectrometry. With a 1:1 fuel-to-oxidant ratio, catalytic processes accounted for 68% of synthesis gas production, and a further 14% gain was achieved when operating in electrolysis mode at 1.4 V. H2/CO ratios of 1.1-2.4 were obtained depending on the fuel-to-oxidant ratio of the feed. Decreasing the fuel-to-oxidant ratio improved the electrical performance and durability of the cell but decreased the overall synthesis gas yield.

Ultra-deep removal of thiophene in coke oven gas over Y zeolite: Effect of acid modification on adsorption desulfurization

The ultra-deep removal of thiophene to 0.1 ppmv level is necessary for coke oven gas to methane process. NaY zeolite was reported to have this potential, and acid sites in NaY play an important role on its desulfurization performance. Based on this situation, sorbents with different types and strengths of acids were prepared by modifying NaY in ammonium nitrate and citric acid solutions. Their desulfurization behaviors in simulated coke oven gas were evaluated by fixed bed. The results show that both ammonium nitrate and citric acid modification on NaY are beneficial to the breakthrough adsorption capacity of thiophene (Qb-thiophene). The NaY after modified in 0.10 mol/L citric acid solution has the highest Qb-thiophene at 100 °C. Ammonium nitrate modification could significantly increase medium-strong Bronsted acid in NaY, whereas citric acid modification mainly increases weak Lewis acid. On medium-strong Bronsted acid sites, thiophene polymerization reaction would occur easily, which would result in the obvious decrease of Qb-thiophene from 71.31 to 35.3 mg/g due to the acid sites covering and micropores blocking by thiophene oligomer. The increase of Lewis acid is conducive to desulfurization. Moreover, on Lewis acid site, the temperature region for thiophene removal is wider than that on Bronsted acid.

A high efficient absorbent for the separation of H2S from low partial pressure coke oven gas.

To high efficiently remove H2S from low partial pressure coke oven gas (COG), a novel activator (tetramethylammonium arginine, [N1111][Arg]) was used to blend with N-methyldiethanolamine (MDEA) for the absorption of H2S. High concentrated [N1111][Arg]-MDEA aqueous solution was used as absorbent. Thermodynamic properties including absorption amount and H2S loading values were measured, then the kinetic apparent absorption rate was calculated based on the change of absorption amount with time. The removal efficiency of H2S in simulated COG was verified in tray towers. Compared with monoethanolamine (MEA)-MDEA and tetramethylammonium glycinate ([N1111][Gly])-MDEA aqueous solutions, [N1111][Arg]-MDEA aqueous solution takes advantages of higher absorption capacity, absorption rate and removal efficiency. Our results showed that the proposed absorbent has good industrial application prospect in coke oven gas desulfurization, because it achieved 100% removal of H2S in the tray tower containing only 4 sieve plates under high concentrated condition (water content < 45%), which may significantly decrease the energy consumption.

Co-electrolysis of simulated coke oven gas using solid oxide electrolysis technology

Coke oven gas is a by-product of coke production for steelmaking and by volume typically consists of 55–60% hydrogen, 23–27% methane and impurities. An estimated 650 million tonnes of coke oven gas are produced worldwide, with up to 50% re-utilised within steelmaking. However, the rest is flared, contributing to carbon emissions and wasting valuable and useful gases. This study has investigated the co-electrolysis of simulated coke oven gas with steam using commercially available solid oxide electrolysis technology for the purposes of recovering hydrogen. The electrochemical performance of an anode supported button cell was characterised using open circuit potential measurements, current-voltage curves and electrochemical impedance spectroscopy. The product gas composition was analysed using quadrupole mass spectrometry. Co-electrolysis of simulated coke oven gas (30/70% methane/hydrogen) with 50% steam achieved a hydrogen amplification of 119% and a purity of 91.7% by volume, balanced mainly in carbon dioxide and carbon monoxide. Theoretically, this corresponds to a worldwide hydrogen production from coke oven gas of 87.6 million tonnes, which is in excess of the current global demand for hydrogen (70 million tonnes). Catalytic steam reforming of methane and the water-gas shift reaction increased the hydrogen content by 89% and a further 16% gain was due to electrochemical steam reduction. Co-electrolysing at high steam-to-carbon ratios was shown to increase hydrogen yield, improve cell performance, maximise methane and carbon monoxide conversion and inhibit carbon deposition. Studies into fuel variability effects show that greater methane contents gave higher hydrogen yields but decreased hydrogen purity and cell performance. Increasing the operating voltage increased the conversion of carbon dioxide into carbon monoxide via promotion of the reverse water-gas shift reaction. The work demonstrates the considerable potential to upgrade coke oven gas using solid oxide electrolysis technology, which could enable greater downstream recovery and purification of hydrogen from an under-utilised industrial waste resource.

Durability of direct-internally reformed simulated coke oven gas in an anode-supported planar solid oxide fuel cell based on double-sided cathodes

A simulated coke oven gas (COG) is used as internally-reformed (IR) fuel in an anode of solid oxide fuel cell based on double-sided cathodes (DSC-SOFC) and the durability of the cell is studied. The DSC-SOFC operates stably for over 240 h when the steam to methane (H2O/CH4) ratio is above 3 with performance degradation of about 0.01% per hour, but it has a larger degradation of about 0.08% per hour when the H2O/CH4 ratio is lower than 2.5. The mechanism of the cell degradation has been analyzed in detail. It is found that the H2O/CH4 ratio approximately equal to 1 is the key point affecting cell performance. The results of cell analysis by energy dispersive spectroscopy and Raman spectroscopy indicate that carbon deposition mainly takes place at the inlet and at the middle of DSC-SOFC. Due to thick anode substrate in this type of cell, carbon distribution on the cross-section reveals that there are two carbon producing areas, one close to the anode surface, and the other near the three-phase boundary. Some of the deposited carbon can be carried by the fuel gas to exhaust which lowers the actual carbon amount in the cell, thus prolonging the cell operation.

Effect of Cr2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

The oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with Cr2O3 addition were studied, and the reduction swelling index (RSI) and compressive strength (CS) of the reduced CVTP with simulated coke oven gas (COG) injection were investigated. The results showed that the CS of the CVTP decreases and the porosity of the CVTP increases with increasing amount of Cr2O3 added. The Cr2O3 mainly exists in the form of (Cr, Fe)2O3 solid solution in the CVTP and as Fe-Cr in the reduced CVTP. The CS of the reduced CVTP increases and the RSI of the reduced CVTP decreases with increasing amount of Cr2O3 added. The limited aggregation and diffusion of metallic iron contribute to the formation of dense lamellar crystals, which leads to the slight decrease for reduction swelling behavior of reduced CVTP. This work provides a theoretical and technical basis for the utilization of CVTP and other Cr-bearing ores such as chromite with COG recycling technology.

Effect of H2S and thiophene on the steam reforming activity of nickel and rhodium catalysts in a simulated coke oven gas stream

In the present work the impact of H2S and thiophene on the steam reforming and water-gas shift (WGS) reactions were studied. The activity of three catalysts i.e. Ni/Al2O3, Ni/mayenite and Rh/Al2O3 was evaluated using an atmospheric fixed-bed lab-scale quartz reactor. A simulated coke oven gas (COG) stream was fed to the reactor. The temperature range studied was 675–900 °C. It was found that the temperature had a significant influence on the degree of poisoning of the catalysts and thus their performance. Regeneration of benzene reforming activity of the poisoned Ni/Al2O3 was achieved after exposing the catalyst to up to 200 ppm of H2S. Rh/Al2O3 outperformed the nickel catalysts in the steam reforming of benzene in the presence of thiophene. Ni/mayenite was the only catalyst able to maintain a noticeable WGS activity in the presence of H2S this result was attributed to the presence of CaO on the surface of this catalyst.

Effect of B2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

Abstract The oxidation induration and reduction swelling behavior of the chromium-bearing vanadium titanomagnetite pellets (CVTP) with B2O3 addition were investigated. Besides, the reduction swelling index (RSI) and compressive strength (CS) of the reduced CVTP were also examined using the simulated coke oven gas (COG). The results suggested that the CS of CVTP was increased from 2448 to 3819.2 N, while the porosity of CVTP was decreased from 14.86% to 10.03% with the increase in B2O3 addition amounts. Moreover, the B2O3 mainly existed in the forms of TiB0.024O2 and Fe3BO5 in both CVTP and the reduced CVTP. Specifically, the CS of the reduced CVTP was elevated from 901 to 956.2 N, while the RSI was reduced from 5.87% to 3.81% as the B2O3 addition amounts were increased. Taken together, B2O3 addition would facilitate the aggregation and diffusion of metallic iron particles, which contributed to reducing the formation of metal iron whiskers and weakening the reduction swelling behavior.

Effect of V&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; Addition on Oxidation Induration and Swelling Behavior of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas Injection into Blast Furnace

Effect of V&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; Addition on Oxidation Induration and Swelling Behavior of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas Injection into Blast Furnace

Effect of Co2O3 on Oxidation Induration and Reduction Swelling of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas

This study discusses the oxidation induration and swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with Co2O3 additions. The reduction swelling index (RSI) and compressive strength of reduced CVTP (CSRC) were investigated with simulated coke oven gas (COG). The results show that the compressive strength (CS) of CVTP decreases from 2448 to 1983 N and the porosity of CVTP increases from 14.86 to 22.49% with increasing Co2O3 additions. The Co2O3 mainly exists in the form of CoFe2O4 in both of CVTP and reduced CVTP, and the CoFe2O4 is hard to be reduced by thermodynamic calculation. The Co-bearing phase mainly distributes on gap edges and among adjacent hematite grains. Many cracks and pores distribute along the grain boundaries and damage the connection of hematite grains. The CSRC decreases from 901 to 376 N, and RSI of reduced CVTP increases from 5.87 to 9.05% with increasing Co2O3 additions. The Co2O3 addition facilitates the aggregation and diffusion of metallic iron particles, and the aggregations of metallic iron thicken the lamellar crystals. The pores and interval of grains enlarge with increasing Co2O3 additions. This study can supply the theoretical and technical basis for the utilization of CVTP and waste residue-bearing cobalt with COG recyclable technology.

Effect of Nitrogen/Oxygen Substances on the Pyrolysis of Alkane-Rich Gases to Acetylene by Thermal Plasma

It is important to convert alkane-rich gases, such as coke oven gas, to value-added chemicals rather than direct emission or combustion. Abundant nitrogen/oxygen substances are present in the actual alkane-rich gases. However, the research about how they influence the conversion in the pyrolysis process is missing. In this work, a systematic investigation on the effect of various nitrogen/oxygen-containing substances, including N2, CO, and CO2,on the pyrolysis of CH4 to C2H2 was performed by a self-made 50 kW rotating arc thermal plasma reactor, and the pyrolysis of a simulated coke oven gas as a model of alkane-rich mixing gas was conducted as well. It was found that the presence of N2 and CO2 was not conducive to the main reaction of alkane pyrolysis for C2H2, while CO, as a stable equilibrium product, had little effect on the cracking reaction. Consequently, it is suggested that a pretreatment process of removing N2 and CO2 should be present before pyrolysis. Both input power and feed rate had considerable effect on the pyrolysis of the simulated coke oven gas, and a C2H2 selectivity of 91.2% and a yield of 68.3% could be obtained at an input power of 17.9 kW.

Removal of Hydrogen Sulfide in Simulated Coke Oven Gas with Low-Grade Iron Ore

The hydrogen sulfide (H2S) removal performance of limonite in the presence of coke oven gas (COG) components (H2, CH4, CO, CO2, and H2O) has been studied in a cylindrical flow-type quartz-made fixed-bed reactor at 300–800 °C under a high space velocity of 51,000 h–1 to develop a novel hot gas cleanup method. The H2S removal behavior by reduced limonite in He does not change at the temperatures examined. On the other hand, the breakthrough curves in 50%H2/He depend on the temperature, and high performance is found at lower temperatures. An investigation of the breakthrough curves of H2S in the presence of COG components at 300–600 °C reveals that the addition of 30%CH4 to 50%H2/He does not influence the performance below 500 °C, whereas the coexistence of 5%CO with 50%H2/30%CH4/He drastically decreases the H2S removal ability of reduced limonite. In addition, the breakthrough curves in 5%CO2 coexisting with 50%H2/30%CH4/5%CO/He are similar to those of 50%H2/30%CH4/5%CO/He. However, the addition of 5%H2O to...