Hydrogen-rich Syngas Production Research Articles

Microwave-Assisted dry reforming of toluene as a model tar compound using low-cost iron catalyst for syngas clean-up

Gasification of waste feedstock such as biomass, waste plastics suffers from high tar yields during hydrogen-rich syngas production. The presence of tars result in lower quality syngas, lower syngas yields, reactor blockage, reactor down time, and costly maintenance. Therefore, removal of tar from syngas during gasification is essential. Catalytic reforming of tars via in-situ syngas cleanup is an effective way of mitigating tars. This work explores the possibility of microwave-assisted catalytic dry reforming of tars for syngas production. Due to its chemical complexity, toluene, which is one of the main tar constituents, could be used as a model tar compound. Toluene dry reforming was studied using the Fe/Al2O3 catalyst under CO2 under the temperature range of 400–700 ℃. The toluene reforming reaction was conducted using microwave and conventional thermal reactors. Under microwave irradiation, CO2 and toluene conversions are boosted to 80% at 500 ℃. Hydrogen and carbon monoxide yields were approximately five times and ten times higher in the microwave reactor at 500 ℃, respectively, compared to the productions obtained in the conventional fixed-bed reactor at 700 ℃. Filamentous carbon was also produced as a valuable side product to improve the economy of this process and such value-added carbon was only observed in the microwave reactor. Three reaction pathways were observed during microwave reaction: the toluene decomposition produces an initial hydrogen and carbon deposit on the catalyst; the formation of methane and benzene suggests toluene hydrodemethylation as a secondary reaction; and toluene hydrogenolysis forms light alkanes such as methane, and through reforming reaction under CO2 to syngas.

Highly dispersed nickel-tuned silica lanthana catalyst: Interplay of morphology and textural properties for hydrogen-rich syngas through the carbon dioxide reforming of methane

Methane (CH4) and carbon dioxide (CO2) are major contributors to the rise in greenhouse gas emissions, exacerbating global warming. Consequently, it is crucial to convert and utilize these gases effectively to mitigate their impact on the atmosphere. Carbon dioxide (dry) reforming of methane (DRM) offers an efficient solution for converting CH4 and CO2 into syngas (H2/CO). In this study, we compare the effectiveness of a robust catalytic system, including a fibrous silica lanthana-supported nickel (NSLF-10) catalyst, to a silica lanthana-supported nickel composite (NSL-C) developed using commercial lanthana and silica. Our investigation focuses on their respective performances in the production of hydrogen-rich syngas through DRM. The NSLF-10 catalyst exhibited improved physicochemical properties such as uniformly dispersed nickel, stronger metal-support interaction, small nickel particle size, and increased surface area, which significantly enhanced the catalytic performance of DRM. Notably, the NSLF-10 catalyst achieved a high conversion of CH4 and CO2 at 85 % and 83 %, respectively, with an elevated H2/CO ratio compared to the NSL-C catalyst, which has a conversion of CH4 and CO2 at 72 % and 64 %, respectively. The unique properties of the NSLF-10 catalyst provide a high synergistic effect between the nickel active sites and SLF support, leading to a high conversion of CH4 and CO2 with no signs of catalytic deactivation.

Hydrogen rich syngas production through sewage sludge pyrolysis: A comprehensive experimental investigation and performance optimisation using statistical analysis

Bioenergy is anticipated to play a significant role in the United Kingdom’s Net Zero 2050 scenario. This study aims to explore the possibility of producing hydrogen-rich syngas using sewage sludge from a wastewater treatment plant located in England, United Kingdom. The primary objective of this study is to experimentally produce hydrogen-rich syngas from sewage sludge through pre-treatment, drying, and pyrolysis. Furthermore, statistical methods have been employed to optimise the performance of the pyrolyser. The individual desirability scores for lower heating value (LHV) and cold gas efficiency (CGE) were estimated to be 0.83902 and 0.85307, respectively. Combining these scores, the overall desirability of the model reached 0.8460, indicating favourable predictive performance. The optimal operational conditions are reported to be a feed rate of 3.0488 revolutions per minute (rpm) and an operational temperature of 800°C. Under these conditions, the highest calculated CGE of 66.31% and the peak LHV value of 18.36 MJ/ m^3 were achieved.

Optimizing Hydrogen-Rich Biofuel Production: Syngas Generation from Wood Chips and Corn Cobs

This study investigates gasification using wood chips (WC) and corn cobs (CC) for hydrogen-rich syngas production. A simulation model developed in Aspen Plus was used to evaluate the performance of biomass gasification. The model incorporates a system of Fortran subroutines that automate the definition of input parameters based on the analysis of biomass composition. Furthermore, the model’s equilibrium constants were adjusted based on experimentally measured gas concentrations, increasing the precision of the variations. The numerical results predicted hydrogen yields of 65–120 g/kg biomass, with 60–70% energy efficiency for steam gasification (versus 40–50% for air gasification). The hydrogen concentration ranged from 34% to 40%, with CO (27–11%), CO2 (9–20%), and CH4 (<4%). The gasification temperature increased hydrogen production by up to 40% but also increased CO2 emissions by up to 20%. Higher biomass moisture content promoted hydrogen production by up to 15% but reduced energy efficiency by up to 10% if excessive. Steam gasification with wood chips and corn cobs shows promising potential for hydrogen-rich syngas production, offering benefits such as reduced emissions (up to 30% less CO) and sustainability by utilizing agricultural residues.

Performance evaluation of carbon-negative syngas production via chemical looping reforming of methane from biomass pyrolysis volatiles

To realize the clean and efficient directional conversion of biomass, chemical looping reforming of biomass volatile CH4 based on a decoupling strategy is expected to carry out carbon-negative production of hydrogen-rich syngas. In this paper, a multi-functional oxygen carrier (NiFe2O4@SBA-16) for encapsulating the active metal oxide component NiFe2O4 with a three-dimensional interconnecting pore molecular sieve SBA-16 was designed. The experimental results showed that the modification strategy of composite metal oxide encapsulation improved syngas selectivity and CH4 conversion based on the fixed-bed reactor. 20 %NiFe2O4@SBA-16 showed 22.1 % CH4 conversion and 92.6 % CO selectivity under 750 °C, and it maintained good cycle stability after 15 cycles. The H2/CO ratio was effectively improved by adding part of CO2 into the feed gas, and the CH4 conversion reached over 35 %. This study provides essential data for the clean preparation of hydrogen-rich syngas from biomass and the development and design of multifunctional oxygen carriers.

Hydrogen-rich syngas production via steam reforming of acetic acid as bio-oil model compound: Effect of CaO addition to NiAl2O4 catalyst

Bio-oil by-products are inevitable with biomass gasification. It is considered a potential resource for hydrogen production via steam reforming. This study investigated acetic acid as a bio-model compound using a NiAl2O4 catalyst. The effect of reaction conditions on hydrogen-rich production has also been discussed, including reaction time (1 h, 3 h, 5 h and 7 h), steam/carbon ratio (S/C = 1–4) and the blend of NiAl2O4 and CaO (1:0, 3:1, 1:1, 1:3 and 0:1). The fresh and spent samples were characterized by XRD, XPS, SEM, BET, etc. The result showed that the CaO addition has several advantages: 1) it increases hydrogen gas purification; 2) it prevents Ni separation from NiAl2O4; 3) it decreases the sintering of NiAl2O4. However, Ca5Al6O14 formation decreases the activity of hydrogen production. In reaction conditions, steam is an essential factor for hydrogen gas production. The S/C ratio = 3 shows the optimum result for hydrogen gas production. Although the higher S/C ratio = 4 can maintain the adsorption activity of CaO, it causes Ni separation from NiAl2O4. The blend of NiAl2O4 and CaO is another essential factor for hydrogen gas production. Adding CaO has increased hydrogen gas production significantly. However, a little CaO in a blend ratio 3:1 does not maintain the stability of the NiAl2O4 structure. In the end, the optimum conditions are S/C ratio = 3 and blend = 1:1 at 650 °C, which produces hydrogen gas yield (2.1 mol/mol) and H2/CO (5.83).

Waste derived ash as catalysts for the pyrolysis-catalytic steam reforming of waste plastics for hydrogen-rich syngas production

Ash derived from the oxidation of waste tire and processed municipal solid waste in the form of refuse-derived fuel have been investigated for their potential as catalysts in the pyrolysis catalytic steam reforming of high-density polyethylene to produce hydrogen-rich syngas. The surface morphology, element distribution, pore structure and metal composition of the ashes were characterized to explore the effects of these ash properties on the catalytic process. Further work using tire ash investigated the influence of the process parameters, catalytic temperature and catalyst plastic ratio in relation to the production of hydrogen and syngas. The results showed that tire ash had a higher specific surface area and pore volume than refuse-derived fuel ash, resulting in a slightly higher hydrogen yield compared to refuse derived fuel ash. An increase in the temperature of the catalytic steam reforming process with the tire ash catalyst significantly increased the hydrogen yield from 13.3 mmol g−1plastic at 800 °C to 83.2 mmol g−1plastic at 1000 °C. At higher catalyst:plastic ratios, the higher amounts of catalyst produced no discernable increase in hydrogen. A tentative reaction mechanism in relation to waste derived ash as catalysts for the steam reforming of plastics pyrolysis volatiles is provided.

Hydrogen-rich syngas production from acetic acid as bio-oil model compound: Effect of intermediate phases (La2NiO4, La2O3 and Ni) of LaNiO3 catalyst

In biomass gasification, bio-oil is the main component of the condensable by-products. It is considered an attractive source for H2 production via steam reforming. This study conducted acetic acid as a bio-oil model compound with LaNiO3 perovskite catalyst due to its high oxygen vacancies and active sites. However, the perovskite structure of LaNiO3 catalysis can be destroyed by produced H2 gas, forming additional phases, including La2NiO4, La2O3 and Ni. The LaNiO3 and different phases were synthesized via a sol-gel method to probe its contribution and interaction with the H2 gas produced from steam reforming of acetic acid. Through 300 min of reaction in steam to carbon (S/C) ratio of 3, the results showed that reduced-LaNiO3 has stable H2 gas production, while the other phases decrease with time. In particular, CH4 is the main composition with the La2O3 phase. A series of characterization techniques, such as XRD, BET, XPS, SEM, TG, H2-TPR and (CO2 and O2)-TPD, were utilized to investigate fresh and used samples. The results showed that the LaNiO3-reduced phase has high oxygen storage capacity, oxygen mobility, oxygen vacancies and surface area, preventing coke deposition. In contrast, the LaNiO3 and La2NiO4 phases have poor coke deposition resistance.

Catalytic evaluation of Pd-promoted Ni-Co/Al2O3 catalyst for glycerol dry reforming: Assessing hydrogen-rich syngas production, kinetics and mechanisms

The Pd-promoted Ni-Co bimetallic catalysts were prepared using ultrasonic-assisted impregnation, and their performance was subsequently assessed in a fixed-bed reactor. The catalyst's performance was evaluated in glycerol dry reforming (GDR) over a range of temperatures, from 873 K to 1173 K and reactant partial pressures ranging from 10 kPa to 40 kPa. The results indicated that as the temperature was raised from 873 K to 1073 K, there was a noticeable rise in both reactant conversion and product yield. However, beyond 1173 K, catalytic performance declined due to glycerol thermal cracking and sintering of the support at high temperatures, resulting in increased carbon formation. The presence of excessive CO2 was found to suppress glycerol adsorption on the catalyst surface, causing a decline in catalytic activity with a CO2 partial pressure of more than 20 kPa, regardless of reaction temperature. Additionally, excess CO2 were found to enhance the side reaction, particularly reverse water-gas shift (RWGS) that related to produce intermediate H2O. Similarly, the glycerol partial pressure was found to impact catalytic performance, with a decrease in performance beyond 20 kPa due to competing reactants between glycerol and CO2. According to the Langmuir-Hinshelwood kinetic mechanism, a dual molecular adsorption site for glycerol and CO2 was appropriate for this GDR reaction, with an associated activation energy of 47.3 kJ mol−1. The GDR reaction was identified as a kinetically controlled process due to its high activation energy, more than 25 kJ mol−1. The plausible mechanism of GDR over Pd-Ni-Co/Al2O3 occurred through the dissociative-type of adsorption of on active metallic sites of the catalysts for both reactant (glycerol and CO2). This was further facilitated by the bifunctional mechanisms based on H2 generated from dissociative adsorption involving both catalyst's basic sites and metallic active sites. This was ascribed to the highly dispersed and strong interaction between metal-support in Pd-promoted Ni-Co bimetallic catalysts.

Hydrogen-Rich Syngas Production via Dry and Steam Reforming of Methane in Simulated Producer Gas over ZSM-5-Supported Trimetallic Catalysts

This study investigated the production of hydrogen-rich syngas from renewable sources using durable and efficient catalysts. Specifically, the research focused on steam methane reforming (SRM) and dry methane reforming (DRM) of simulated producer gas from biomass steam gasification in a fluidized bed reactor. The catalysts tested are ZSM-5-supported nickel-iron-cobalt-based trimetallic catalysts in different ratios, which were prepared via the wet impregnation method. Synthesized catalysts were characterized using XRD, BET, H2-TPR, and SEM techniques. The results of the SRM with the simulated producer gas showed that the 20%Ni-20%Fe-10%Co/ZSM-5 trimetallic catalyst, at a gas hourly space velocity (GHSV) of 12 L·h−1·g−1 and reaction temperature of 800 °C, achieved the highest CH4 conversion (74.8%) and highest H2 yield (65.59%) with CO2 conversion (36.05%). Comparing the performance of the SRM and DRM of the simulated producer gas with the 20%Ni-20%Fe-10%Co/ZSM5 at a GHSV of 36 L·h−1·g−1 and 800 °C, they achieved a CH4 conversion of 67.18% and 64.43%, a CO2 conversion of 43.01% and 52.1%, and a H2 yield of 55.49% and 42.02%, respectively. This trimetallic catalyst demonstrated effective inhibition of carbon formation and sintering, with only 2.6 wt.% carbon deposition observed from the thermo-gravimetric analysis of the used catalyst from the SRM of the simulated producer gas, thus promoting the potential of the ZSM-5-supported trimetallic catalysts in methane reforming.

Hydrogen-rich syngas production and insight into morphology-kinetics correlation for furfural residue steam gasification in a bubbling fluidized bed

Biomass steam gasification technology has attracted considerable interest for its potential of low-cost and high-efficiency in hydrogen production. However, there is still a large knowledge gap regarding morphology-kinetic correlation. To avoid the technical difficulties of thermogravimetric analysis and fixed bed studying steam gasification kinetics, this work pursues the design and building of a visualized bubbling fluidized bed with an online analysis system. According to the morphology evolution of biomass real-time observed by a high-speed camera, the shrinkage ratio during high-temperature gasification in a fluidized bed has been first deduced. Moreover, based on accurate monitoring of the gas products releasing behavior, multiple kinetic models were applied to evolve the activation energy at different carbon conversion efficiencies (CCE). The results showed that the synergistic regulation of steam concentration and temperature achieved a high H2/CO ratio (2.46) and H2 yield (869.5 L/kg). A comparative analysis of the coupling relationship between shrinkage ratio, activation energy and CCE successfully separated the volatile precipitation and char gasification processes. It was also revealed that the shrinkage rate peaked at the transition from pyrolysis to char gasification (20 % CCE). At CCE below 20 %, the reaction mechanism tended towards a nucleation and growth mechanism. As CCE reached 20 %, the reaction form shifted. Subsequently, the chemical reaction mechanism controlled the main reaction, and the average apparent activation energies of H2, CO2 and CO were 86.76, 31.27 and 39.90 kJ/mol, respectively. This work provides new insights and a theoretical basis for understanding and modeling the biomass steam gasification process in fluidized beds.

Simulation of the deoxygenated and decarburized biomass cascade utilization system for comprehensive upgrading of green hydrogen generation

Steam gasification of biomass is of great significance for achieving efficient hydrogen-rich syngas production. However, the yield and the quality of H2 in the product require further improvements. In this study, a strengthened biomass cascade utilization system via synergistic deoxygenation and decarburization is investigated. The system is composed of a deoxygenated and decarburized gasification reactor and a deoxidizer and decarburizer material regenerator. In the gasification reactor, a series of deoxidizer and decarburizer materials, CaO-Fe (Ca: Fe > 1.0), are applied for accomplishing high-quality hydrogen production; In the regenerator, the deoxidizer and decarburizer material is regenerated (CaCO3+ Ca2Fe2O5→CaO–Fe) with released gas utilization. The effects of gasification temperatures, Ca/Fe, H2O/C, and (CaO + Fe)/B mole ratios are evaluated by Aspen Plus, achieving comprehensive optimization of the parameters. The H2 yield reaches 68.16 mol s−1 kg−1 biomass and the H2 concentration is up to 93.58 vol%, which increases by 254.45 % and 109.87 % compared with the results without deoxygenation and decarburization. Additionally, the deoxidizer and decarburizer material can be completely regenerated via released gas reduction, thereby ensuring the consistent looping of the entire system. This paper sheds light on the synergistic deoxygenation and decarburization methodology for biomass-to-hydrogen generation, which provides a robust guidance for further experiments in the future.

Plasma steam gasification of surgical mask waste for hydrogen-rich syngas production

During the COVID-19 pandemic, thousands of tons of infected surgical mask waste (SMW) were dumped every month without a real vision to manage them. Although the world has successfully passed this critical period, this situation is likely to recur again in the future, therefore a serious industrial eco-solution must be developed to deal with SMW. In this regard, this research aims to investigate the possibility of using arc plasma gasification performances as an eco-friendly energy technique to dispose SMW and convert it into clean energy products. NK90 face masks were used as a feedstock after having converted them into uniform granules using shredding and palletizing pre-treatment processes. The experiments were carried out on a continuous gasification plant with a capacity of 10.4 kg/run with a water vapor agent at 2600 K. Also, the effect of different gasification parameters (arc plasma energy and water vapor (S) to SMW (C)) on the yield and composition of the formulated products was studied. The results showed that under the optimal conditions (56.9 kW, plasma temperature = 2600 K and S/C ratio = 1.45), syngas was produced with a high yield (3.4 m3/kg) and with H2 (49.21%), CO (21.7%), CH4 (12.78%), CO2 (5%), and C2H2 (2.91%) contents. The obtained syngas showed the lower heating value of 14.5 MJ/Nm3 which is 42% higher than that produced from plasma gasification of biomass. Also, a small amount of tar content (29.4 g/m3) rich in a benzene compound (46.8%) was synthesized. The plasma energy and energy conversion efficiency were estimated at 56.9 kW and 51.7%, respectively. Based on these results, plasma steam gasification can be used for utilization of SMW and its conversion into hydrogen-rich syngas for further clean-energy applications.

Parametric Modelling Study to Determine the Feasibility of the Co-Gasification of Macroalgae and Plastics for the Production of Hydrogen-Rich Syngas

Seaweed is of importance to the environment due to properties such as its CO2 sequestration capability. On the other hand, plastic is a versatile material important to society. Unfortunately, the abundance of both plastics and seaweed represents a challenge due to the need of adequate waste management. At first, algae and plastics might not appear suitable for energy recovery; however, with co-gasification, the results are promising. This work presents a model to simulate the co-gasification of Chlorella vulgaris, Sargassum fluitans, and Sargassum natans with plastics. The effect of the gasification temperature (650–850 °C), equivalence ratio (0.25–0.45), and plastics/biomass ratio (0.0–1.0) on the produced gas’s lower heating value, tar concentration, and composition is assessed. Moreover, the environmental performance of using plastic to enhance the syngas produced from the co-gasification with sargassum is assessed using the life cycle assessment methodology. The results indicate that the lower heating value increases with the temperature and plastics/biomass ratio. Moreover, tar increases with the quantity of plastics, varying between 20 and 50 g/Nm3. Finally, adding plastics to algae during gasification reduces the variability in the syngas composition, simplifying the post-processing stage. With respect to environmental performance, gasification has an impact similar to those of pyrolysis and recycling, but the performance could improve with sufficient research and development.

Production of hydrogen-rich syngas through microwave-assisted gasification of sewage sludge in steam-CO2 atmosphere

Microwave-assisted gasification (MWG) of sewage sludge (SS) was conducted, and the influence of gasification agents, i.e., steam and CO2, on the production of syngas and the generation path of H2 were systematically investigated. The results showed that the steam-CO2 mixed atmosphere was helpful to increase the yield of syngas (with the maximum yield of 45.3 wt%), and improve the quality of syngas. The maximum concentration of H2 reached 63.73 vol% (with H2 and CO total concentration of 68.93 vol%) when the steam/CO2 ratio (vol./vol.) was 36, and the maximum high heating value (HHV) of the syngas was about 10.51 MJ/Nm3 close to that of commercial syngas. H2 was mainly produced between 400 and 700 °C, and the maximum concentration could reach 76.2 vol% at 700 °C under the steam/CO2 ratio of 36. Steam and CO2 showed a good synergistic effect to jointly promote the production of H2 during MWG. The produced tar was mainly composed of hydrocarbons, oxygen-containing compounds and nitrogen-containing compounds, and steam could promote the formation of oxygen-containing compounds in tar. With the increase of steam/CO2 ratio, a large amount of fixed carbon was consumed through Boudouard reaction and steam reforming reaction. More than 50 % of P and K in SS were retained in char, which makes it a valuable product for soil amendment. Additionally, it was calculated that the MWG of 1 kg SS could be converted into 7801 kJ of electric energy through SOFCs, which could totally replace the electrical energy required for MWG of 1 kg SS, and the energy recovery efficiency (η) could be increased to 93.64 % in large-scale production.

Response surface optimization of hydrogen-rich syngas production by the catalytic valorization of greenhouse gases (CH4 and CO2) over Sr-promoted Ni/SBA-15 catalyst

Dry reforming of methane (DRM) which utilizes CO2 and CH4, is a more efficient and environmentally friendly syngas production method. However, since the technique is endothermic, catalyst deactivation from sintering and carbon deposition has prevented its industrial implementation. This study investigated the effect of Strontium (Sr) promoter on Ni-based catalyst synthesized on SBA-15 support via the impregnation method. The incorporation of Sr as a promoter has demonstrated distinct advantages, primarily attributed to its remarkable capability to inhibit carbon formation. This property imparts a notable enhancement in the stability of the catalyst, thereby extending its operational lifespan and maintaining consistent catalytic performance. The physicochemical properties of the fresh catalyst were observed by using various characterization techniques such as X-Ray diffraction (XRD) analysis, N2 physisorption analysis, field emission scanning electron microscopy (FESEM), and temperature programmed reduction using hydrogen as the probing gas (TPR-H2). The catalysts were tested in DRM reaction using a tubular fixed bed reactor at 800 °C with an equimolar feed ratio. Overall, 1% Sr promoted Ni/SBA-15 showed enhanced performance having CO2 and CH4 initial conversions of 88.5% and 96.5%, respectively while remaining stable for 320 min on stream. Furthermore, the predicted optimal condition was 713.73 °C and a feed gas ratio (CH4:CO2) of 1.12, with CO2 and CH4 conversion rates of 69.59% and 84.83%, respectively, resulting in an H2:CO ratio of 1.00. Slight differences from the predicted values were considered insignificant, validating the Srb catalyst at a 95% confidence level with a 5% likelihood of error in the RSM model.

Ex-situ catalytic upgrading of biomass pyrolysis volatiles over thermal-decomposition products of spent lithium-ion batteries for bio-oil deoxygenation and hydrogen-rich syngas production

Spent lithium-ion batteries rich in transition metals are highly potential to catalyze the biomass pyrolysis process. This research provided insight into the performance and mechanism of ex-situ catalytic upgrading of biomass pyrolysis volatiles over the thermally pyrolyzed spent Ni–Co–Mn ternary batteries (PyNCM) for the first time. The results showed that the PyNCM exhibited high catalytic activities for the secondary decompositions of pyrolysis volatiles, resulting in 12.6% reduction on bio-oil yield and 57.5% promotion on syngas productivity. The magnetic Ni and Co compounds in PyNCM were primarily responsible for the enhanced volatile deoxygenations, and the maximum H2 yield reached 2.66 mmol g−1 biomass. Two levels of synergistic catalysis were identified: (1) the synergy among the transition metals established multiple active centers to promote the H2 selectivity; (2) the non-magnetic graphite and lithium could probably improve the dispersion and surface oxygen vacancies of nickel and cobalt to further enhance the catalytic activity.

Hydrogen production through agro-residue gasification and adsorptive separation

The present work reports on the characterization of mixed agro-residue pellets and their subsequent use for syngas generation in a laboratory-scale downdraft gasifier utilizing the mixture of oxygen and steam as the gasifying agent (equivalence ratio/steam to biomass ratio: 0.21/2.15). Pure hydrogen is realized in a vacuum pressure swing adsorption system using zeolite 13X adsorbent. Regarding pellets, the high ash content (11.46 ± 0.38 wt%) and the presence of inorganic elements (potassium, silicon, calcium) dictate gasification process level interventions. The key requirement established experimentally is maintaining the reactor temperature under 900 °C for a clinker-free operation. This prerequisite, accomplished through an optimized char-ash extraction rate, enables the consistent production of hydrogen-rich (42.2 ± 0.9 vol%) syngas with a lower heating value of 8.3 ± 0.2 MJ/Nm3 at a gross cold gas efficiency of 78.9%. The cyclic separation system operates at a pressure ratio of 7.5 and continually generates pure hydrogen with minimal contaminants. The oxy-steam gasification of high ash feedstock in a near-ambient fixed-bed reactor and its integration to a low-pressure swing adsorption system for practical multi-specie syngas separation with quality assessment of the produced hydrogen are the main novelty features.

Biomass steam gasification for hydrogen-rich syngas production over fly ash-based catalyst pretreated by coupling of washing and calcination

Biomass gasification to produce syngas is promising, but the limited hydrogen content of the syngas restricts its potential applications. This study proposed an efficient thermochemical approach that used cost-effective fly ash pretreated with washing and calcination (WCFA) as a catalyst to enhance hydrogen-rich syngas production from biomass steam gasification. Catalyst characterizations indicated that washing removed most chloride salts in raw fly ash by dissolution, and subsequent calcination decomposed Ca-containing compounds into CaO, resulting in smaller catalyst grains, more developed pore structure, and greater capability and reaction rate of CO2 sorption. With WCFA, the H2 release during gasification was prolonged by ∼10 min and its release peak increased by over 1.5 times, compared to no catalyst. Consequently, the cold gas efficiency, syngas yield, and H2/CO ratio increased from 53%, 792 mL/gbiomass, and 0.39 for no catalyst to 72%, 1132 mL/gbiomass, and 1.05 for WCFA. The WCFA catalyst calcined at 800 °C for 60 min was optimal for H2 formation, due to its enriched CaO composition and improved porosity, which effectively catalyzed volatiles cracking/reforming and absorbed CO2 to lead the chemical equilibrium of water gas shift reaction move foward.

Hydrogen-rich syngas production from steam gasification of Brazilian agroindustrial wastes in fixed bed reactor: kinetics, energy, and gas composition

Hydrogen-rich syngas production from steam gasification of Brazilian agroindustrial wastes in fixed bed reactor: kinetics, energy, and gas composition