Hydrogen-rich Gas Production Research Articles

Evaluating compost for hydrogen and methane rich gas production via supercritical water gasification

The compost produced from organic wastes (MSW, city market’s wastes and wood dust) was selected to be processed via supercritical water gasification (SCWG) in order to produce gas product consisting of hydrogen and methane mainly. The effects of parameters such as temperature, reaction time and KOH as an additive were determined and around 55 vol.% of H2 and CH4 in the gas product was found after 30 min reaction time together with KOH, at 500 oC. The red mud catalysts did not improve the gasification yields even though they increased the calorific value of the product gas.

Assessment of biochar developed via torrefaction of food waste as feedstock for steam gasification to produce hydrogen rich gas

In this study, the torrefaction of food waste was carried out using a thermogravimetric analyzer (TGA) to produce biochar and assess its suitability as feedstock for steam gasification. Torrefaction was conducted at temperature from 230 to 290 °C and the heating rate from 10 °C/min to 30 °C/min. Subsequently, the detailed characterization was conducted using proximate, elemental, lignocellulosic, nutrient analysis, and TGA analysis. The proximate and elemental analysis showed that biochar had the highest fixed and elemental carbon at the highest temperature (290 °C) and lowest heating rate (10 °C/min). Similarly, TGA indicated that increase in temperature increased the mass loss, however, increase in heating rate did not yield much change in mass loss. Additionally, lignocellulosic and nutrient analysis showed that lignin fraction increased (up to 80%) with increases in severity of the torrefaction due to significant decomposition of hemicellulose, cellulose, starch, proteins, and lipids. Thereafter, the kinetic parameters (activation energy, pre-exponential factor) of torrefaction of food waste were determined using the two-step decomposition model which showed a good fit with experimental data. Finally, the biochar developed was used for energy production using steam gasification which produced syngas with maximum yield of 3.75 m3/Kg and having hydrogen fraction of around 65% at the optimal conditions (temperature: 290 °C, heating rate: 10 °C/min).Graphical

Improving hydrogen-rich gas production from biomass catalytic steam gasification over metal-doping porous biochar

Biomass to green H2 is a new route to produce sustainable energy. This study aimed to boost H2-enriched gas production via gasification-catalytic steam reforming (GCSR) process of wheat straw (WS) over Ni, Fe, or Zn-doped carbon materials (MDCMs). Initially, steam injection rate (1 g/min) and residence time (15 min) was optimized based on the tradeoff between energy consumption and H2-rich gas generation. The largest gas yield (90.77 mmol/g) and the lowest H2 production efficiency (ƞ: 7.89 g CO2/g H2) were observed for WS-derived biochar. Clearly, it was found MDCMs were favorable for reducing CO2 production due to the strengthened CO2 reforming reactions catalyzed by metal active sites. A higher ƞ (6.72 g CO2/g H2) was achieved for Ni-doping biochar (Ni/C). Importantly, Ni/C showed the ultrahigh carbon conversion efficiency (99.47%) and great tar elimination performance. Overall, GCSR process over MDCMs is a newly promising way to valorize biomass into H2-rich gas.

Prediction and optimization of hydrogen-rich gas production from sewage sludge via a combined process of hydrothermal carbonization, pyrolysis, and reforming

Aiming at the sustainable management of sewage sludge (SS), an alternative process combining with hydrothermal carbonization (HTC), pyrolysis, and steam reforming was proposed in this study for SS to energy/fuels. Models were developed by multiple linear regression, Merrick correlations and kinetics for assessing its potential of hydrogen-rich gas production. A good agreement was found between the simulation results by these proposed models and experimental data. The sensitivity analysis shows that HTC could improve the H2 fraction and decreased the tar concentration in the gas significantly. The integration of steam reforming facilitated the production of H2 and CO along with the significant decrement of tar concentration. The optimal H2 fraction of 61.16 vol%, lower heating value (LHV) of 14.34 MJ/Nm3, gas yield of 1.42 Nm3/kg and tar concentration of 0.28 g/Nm3 in the gas could be achieved by the proposed process, respectively. This work provides an alternative way for SS to energy/fuels.

Hydrogen-Rich Gas Production by Steam Reforming and Oxidative Steam Reforming of Methanol over La0.6Sr0.4CoO3-δ: Effects of Preparation, Operation Conditions, and Redox Cycles.

La0.6Sr0.4CoO3-δ (LSC) perovskite, as a potential catalyst precursor for hydrogen (H2)-rich production by steam reforming of methanol (SRM) and oxidative steam reforming of methanol (OSRM), was investigated. For this purpose, LSC was synthesized by the citrate sol-gel method and characterized by complementary analytical techniques. The catalytic activity was studied for the as-prepared and prereduced LSC and compared with the undoped LaCoO3-δ (LCO) at several feed gas compositions. Furthermore, the degradation and regeneration of LSC under repeated redox cycles were studied. The results evidenced that the increase in the water/methanol ratio under SRM, and the O2 addition under OSRM, increased the CO2 formation and decreased both the H2 selectivity and catalyst deactivation caused by carbon deposition. Methanol conversion of the prereduced LSC was significantly enhanced at a lower temperature than that of as-prepared LSC and undoped LCO. This was attributed to the performance of metallic cobalt nanoparticles highly dispersed under reducing atmospheres. The reoxidation program in repetitive redox cycles played a crucial role in the regeneration of catalysts, which could be regenerated to the initial perovskite structure under a specific thermal treatment, minimizing the degradation of the catalytic activity and surface.

Addition of torrefied algal biomass to improve land-based biomass gasification for hydrogen-rich gas production

Steam co-gasification of two kinds of biomass with different activities could generate synergetic effect on the fuel gas production. In this study, steam co-gasification of torrefied biochar from seaweed with land-based biomass, i.e., cedar wood and rice husk, was performed for the production of hydrogen(H2)-rich fuel gas, in which seaweed was torrefied at different temperatures (i.e., 200, 250 and 300 °C), and the performance of co-gasification was evaluated at three different gasification temperatures (i.e., 650, 700 and 750 °C) under atmospheric condition with three different steam flow rates (i.e., 0.05, 0.10 and 0.15 g/min) in a fixed bed reactor with a feed biomass and torrefied biochar weight ratio of 1:1. Taguchi's orthogonal array of L9 (34) was used to determine the importance of each parameter on the amount of H2 produced. It is found that the optimum parameters resulting in the highest H2 gas were the co-gasification cedarwood with the torrefied seaweed obtained at a torrefaction temperature of 300 °C at a co-gasification temperature of 750 °C with a steam flow rate of 0.10 g/min. Especially, at this condition, the produced H2 gas was nearly twice higher than that from cedarwood individual gasification and 11 % less tar produced than the calculated result.

CaMoO4-enhanced Ni-CaO bifunctional catalyst for biomass pyrolysis to produce hydrogen-rich gas

The development and utilization of bifunctional catalysts facilitated hydrogen-rich gas production from biomass pyrolysis to achieve high-value biomass conversion. The effects of different secondary metals (Fe, Mo, Ce) doping and Mo addition ratios on the performance of biomass catalytic pyrolysis for hydrogen production were investigated. The results showed that the Mo0.5Ni1Ca7 catalyst had the best catalytic activity, where the H2 percentage was 69.59 vol%, and the yield reached 617.57 mLgbiomass−1. The CO2 concentration of the Mo0.5Ni1Ca7 catalyst was reduced by 10.6% compared to the Ni1Ca7 catalyst, which enhanced the adsorption performance of the catalyst. The intense interaction between Mo and Ca formed CaMoO4, which inhibited the formation of CaCO3 and promoted the dispersion of the active phase. The Mo0.5Ni1Ca7 catalyst had the largest NiO/Ni (OH)2 ratio and Mo6+/Mo5+ ratio, further enhancing the catalyst's stability and catalytic activity. Considering the effect of pyrolysis temperature on H2 concentration and yield, it was found that 600 °C was a relatively suitable catalytic pyrolysis temperature. This paper explored using Mo-modified catalysts in biomass catalytic pyrolysis for the first time, providing new ideas for developing bifunctional adsorption catalysts. Eventually, it provided a new way for biomass pyrolysis for hydrogen production technology.

Experimental Study on the Preparation of Hydrogen-Rich Gas by Gasifying of Traditional Chinese Medicine Residue in a DFB Based on Calcium Looping

Using traditional Chinese medicine residue biomass as the raw material and industrial limestone as a carbon absorbent, this paper investigates the production of hydrogen-rich synthesis gas in a pilot-scale calcium looping dual fluidized bed (DFB) system. The study focuses on analyzing the distribution characteristics of temperature and pressure, as well as the operation and control methods of the DFB system. The effects of reaction temperature, material layer height (residence time), water vapor/biomass ratio (S/B), and calcium/carbon molar ratio (Ca/C) on gasification products are examined. The experimental results demonstrate that as the temperature (600–700 °C), S/B ratio (0.5–1.5), Ca/C ratio (0–0.6), and other parameters increase, the gas composition shows a gradual increase in the volume content of H2, a gradual decrease in the volume content of CO, and an initial increase and subsequent decrease in the volume content of CH4. Within the range of operating conditions in this study, the optimal conditions for producing hydrogen-rich gas are 700 °C, an S/B ratio of 1.5, and a Ca/C ratio of 0.6. Furthermore, increasing the height of the material layer in the gasification furnace (residence time) enhances the absorption of CO2 by the calcium absorbents, thus promoting an increase in the volume content of H2 and the carbon conversion rate in the gas.

Supercritical water Co-gasification of biomass and plastic wastes for hydrogen-rich gas production using Ni-Cu/AC-CaO catalyst

Supercritical water gasification (SCWG) of sugar beet pulp (SBP) as lignocellulosic biomass and high-density polyethylene (HDPE) as plastic waste to produce hydrogen-rich gas is investigated. Factors affecting SCWG of SBP were investigated by experimental design method. The variable parameters included temperature (385–460 °C), reaction time (10–30 min) and feedstock concentration (0.25–3.25 wt%). 460 °C, 30 min and 1.04 wt% were identified as optimal points for the highest hydrogen yield. SCWG of SBP and HDPE blend with different ratios were carried out to investigate the synergetic effect of blending on the efficiency of total gas and hydrogen yields. Hydrogen production increased with increasing the ratio of HDPE in the feedstock mixture and reached its maximum of 8.95 mmol/g at the ratio of 40 wt% and then started to decrease. Using a low-cost catalyst (Ni–Cu/AC-CaO) for SCWG of blended feedstock enhanced the total gas and hydrogen yields by factors of 2.4 and 3.8, respectively.

Ni-based nanoparticle catalyst for enhancing hydrogen production in coffee residue gasification and applying carbon deposits catalyst in electrochemical energy storage

In this work, catalytic gasification combined with in-situ CO2 capture over Ni-CaO/Ca2Fe2O5 NPs catalyst is studied for hydrogen-rich synthesis gas production. The Ni-CaO/Ca2Fe2O5 NPs catalyst determined remarkable catalytic performance in changeover ability and synthesis gas. The carbon deposited Ni-CaO/Ca2Fe2O5 spent NPs catalyst was successfully reutilized as an electrode for supercapacitor using KOH electrolyte. This recycled catalyst demonstrates an extraordinarily higher capacity than the pristine catalyst. Attributable to these benefits, the carbon deposited spent catalyst conveyed a high specific capacitance of 1455 F g−1 established electrode mass and high-power density 19,224 W kg−1 with long cycle stability (96% retention after 10,000 cycles). The minimal cost of carbon deposited spent catalyst, along with this method for efficiently recycled carbon-deposited spent catalyst for energy storage applications, might be a promising and cost-effective spent catalyst reutilization technique.

Utilization of PET (waste) via hydrothermal co–gasification with sorghum for hydrogen rich gas production

In this study, the applicability of hydrothermal biomass co–gasification for utilizing polyethylene terephthalate (PET) based waste was investigated. For this purpose, hydrogen rich gas production was realised by hydrothermal co–gasification of sorghum biomass with virgin and waste PET mixtures at 500 °C, and the gasification performances were compared. The feedstock/water ratio (%, w/v) was significantly effective on the gasification process in terms of gas yields, gas, and liquid product distributions. Synergistic effects were observed in hydrogen formation in co–gasification of PET and sorghum. The amount of hydrogen obtained from the co–gasification of PET and sorghum was 4.0 mol H2/kg feed higher than the sum of total amount of hydrogen obtained from the individual gasification of PET and sorghum. GC/MS analysis showed that liquid contents were also affected from experimental conditions. The use of catalysts increased the gasification and carbon conversion yields regardless of the type. Although KOH was the most effective single catalyst on hydrogen yield, the catalyst combinations were more effective with promoted activities in terms of hydrogen yields and CO2 capture. Hydrogen yield, which was 12.9 mol H2/kg feed without catalyst, increased to 31.0 (±0.9) mol H2/kg in the presence of K2CO3/CaO catalyst combination for virgin PET/sorghum mixtures and 28.1 (±0.3) mol for PET waste plastics/sorghum mixtures. For the PET waste plastics/sorghum mixtures with the binary catalyst combinations (K2CO3/CaO and KOH/CaO), the CO2 mole fractions of the product gas mixtures were below 1% and the hydrogen contents of the obtained gas mixtures were above 90%. The results of the study show that pet–based plastic wastes can be effectively utilized to produce hydrogen rich gas, by co–gasification with biomass.

Valorization of Sugarcane Bagasse for Hydrogen-Rich Gas Production using Thermodynamic Modeling Approach

Hydrothermal gasification also known as supercritical water gasification (SWG) has been considered a promising approach for converting wet biomass such as sugarcane bagasse into high-quality syngas. This study presents the thermodynamic modeling of the hydrothermal gasification of sugarcane bagasse using Aspen Plus. The effects of process parameters on the composition and yield of product gases were also investigated. It was found that the effect of temperature and biomass concentration were significant in the production of hydrogen-rich gas, while less impact was observed with pressure. The hydrogen gas (H2) produced with the highest mole fraction (56.70 mol%) and yield (103.26 kmol/kg) was obtained at 750°C and low biomass concentration of 10 wt%, while the lowest yield (1.52 kmol/kg) and mole fraction (2.45 mol%) of H2 were obtained at 450°C and high biomass concentration of 50 wt%. Findings from this study also showed that the highest net calorific value (17.55MJ/kg) was reached at 450˚C and 50 wt% of biomass concentration. This study would help to consolidate research on hydrothermal gasification of sugarcane bagasse and optimization of experimental processes and also serve as an important benchmark in the utilization of biomass as a clean energy source for future projects.

Two-Step Gasification of Cattle Manure for Hydrogen-Rich Gas Production: Effect of Gasification Temperature, Steam Flow Rate, and Catalysts

Highlights Steam gasification parameters of cattle manure char were optimized. Effects of slow heating and fast heating modes on char gasification were analyzed. 1.92 m3/kg syngas yield and 88.72% C-conversion efficiency were obtained at 850 °C, with fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst. Abstract. This study investigated the hydrogen-rich gas production from cattle manure char by steam gasification. The characteristics of char were studied by proximate analysis, ultimate analysis, thermogravimetric analysis, and XRD analysis. The effects of temperature, heating mode, steam flow rate, and catalyst on syngas yield, hydrogen yield, gas composition, heating value, and carbon conversion efficiency were explored. The results showed that the fixed carbon content in cattle manure char was 34.46%, an increase of 2.24 times compared with that of cattle manure, and the cattle manure char had a high fixed carbon content and thermal stability. The steam gasification indicated that the high temperature and fast heating could obtain high syngas and hydrogen yields. The steam flow rate played an important role in the char and steam reforming reactions. The SiO2 and ash catalysts had an inhibitory effect on the steam gasification of char. However, the K2CO3 catalyst improved the syngas and hydrogen yields. The optimal parameters in this study were 850 °C, fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst. By comparison, the syngas and hydrogen production of char were better than those of biomass. As a result, the steam gasification of char was a promising method for producing hydrogen-rich gas. Keywords: Catalysts, Cattle Manure Char, Hydrogen, Steam Flow Rate, Steam Gasification.

Partial oxidation of methane to syngas over SmCoO3-derived catalysts: the effect of the supercritical fluid assisted modification of the perovskite precursor

Syngas is crucial raw for the production of hydrogen-rich gas for green energy and for various petrochemical processes. Herein, we report the Syngas production via partial oxidation of methane (POM) on new SmCoO3-derived catalysts produced from simple individual precursor. Precursor modified by supercritical antisolvent precipitation (SAS) involving supercritical CO2 yields SmCoO3 with finer grains, and the catalytic activity of respective Co/Sm2O3 composite formed in situ during POM is considerably enchanced. This catalyst does not undergo coking, and provides CO and H2 yields of 75–88% for 55 h at 900 °C, thereby being the most efficient POM catalysts derived from non-substituted LnCoO3. Thus, the prospects of exploiting SAS modification of the precursor for SmCoO3 to enhance the catalytic activity of the daughter Co/Sm2O3 composites are demonstrated for the first time. Given the overall simplicity in production, studied Co/Sm2O3 composites can also be convenient systems for further development of POM catalysts.

Use of coals and wastes in a co-gasification process aimed at producing hydrogen rich gas

The use of low-quality coals and flotoconcentrates is currently severely limited, and the problem of managing municipal waste from anthropogenic activities is currently a challenge. The problems of reducing carbon dioxide emissions, utilizing the energy potential of waste and increasing its recycling have an impact on the costs of electricity production. Considering the abundant streams of unused fuels, they can be considered as attractive energy materials, so environmentally-friendly and cost-effective options for their utilization should be developed. A study was conducted using steam co-gasification technology on selected coals, flotation concentrates and Refuse Derived Fuel (RDF) alternative fuel. Selected low-quality coals were combined with RDF alternative fuel in a process aimed at hydrogen production. The experiments produced gas with hydrogen concentrations ranging from 67% (vol.) to 68% (vol.) with low methane concentrations. It was observed that the addition of alternative fuels helped to increase the hydrogen concentration in syngas. Attention was paid to the catalytic ability of the metal oxides contained in the fuel blend, with particular reference to K2O and Al2O3 and TiO2.

Pyrolysis of typical plastics and coupled with steam reforming of their derived volatiles for simultaneous production of hydrogen-rich gases and heavy organics

Pyrolysis is a thermochemical route for converting waste plastics into hydrocarbons that might be further upgraded to fine chemicals via the process such as hydrotreatment. In this study, the pyrolysis of five typical plastics (PE, PP, PVC, PS and PET) and steam reforming of their derived volatiles were coupled in one process, named as pyro-reforming. The reaction behaviors, especially the property of their derived cokes, in the pyro-reforming were investigated. The results indicated that the volatiles from the pyrolysis of PE had the highest reactivity with steam to produce H2 of the highest yield, followed by that of PP, PVC, PET and PS. The Cl in PVC promoted nickel sintering, enhanced formation of heavy aromatics through aromatization. Moreover, the existence of Cl interrupted formation of carbon nanotube, forming the highest amount of coke with hemp rope-like fiber form of very coarse surface. This was very different from the carbon nanotube form of coke with smooth surface and uniform outer/inner diameters from the pyro-reforming of PE or PP. The pyro-reforming of PET or PS generated mainly the aromatic intermediates that were chemically more inert in steam reforming, forming polymeric type of coke with no carbon nanotube morphology and very low crystallinity.

Hydrogen-Rich and Clean Fuel Gas Production from Co-pyrolysis of Biomass and Plastic Blends with CaO Additive.

The treatment and disposal of waste biomass and plastics are of great importance to achieve both waste management and resource recycling. In this work, pyrolysis of biomass and plastic blends were investigated to identify the influence of temperature and in situ CaO addition on the production of hydrogen-rich, HCl-free, and low tar content fuel gases. The results show that the increase in temperature and the use of CaO significantly improved both the quantity and quality of the fuel gas and mitigated the formation of tar compounds and HCl. Moreover, H2 yield was significantly improved from 0.30 to 3.68 mmol/g with the increase in temperature from 550 to 850 °C. Also, the use of in situ CaO significantly increased the H2 yield by 28–88%. The H2/CO ratio was also enhanced from 0.35 to 1.50 with the temperature increase and CaO addition. Tar removal efficiency reached approximately 70.09% with the use of CaO at 850 °C. The produced HCl gas could be effectively absorbed by CaO through dechlorination reactions to form CaClOH at a highest mitigation efficiency of 92.37%. The results could be used to develop clean and efficient treatment technologies of waste biomass and plastics.

Hydrogen-rich gas production from hydrothermal gasification of fuel pellets obtained from co-pelletization of agricultural residues

Hydrothermal gasification of fuel pellets obtained from co-pelletized agricultural residues such as barley straw, canola hull and oat hull was performed in a batch reactor. The effects of process conditions such as temperature (300–500 °C), reaction time (20–60 min) and feed-to-water mass ratio (1:05–1:15) were investigated to optimize the gasification process for large gas yields. The maximum yield of gas was attained at the temperature, reaction time and feed-to-water mass ratio of 500 °C, 60 min and 1:10, respectively. The highest hydrogen gasification efficiency (113%), hydrogen selectivity (52%), cold gasification efficiency (41%) and heating value of gas (920 kJ/Nm3) were found for the hydrothermal gasification of canola hull pellet at the optimal conditions. The temperature was the most paramount variable followed by reaction time and feed-to-water mass ratio. Physicochemical characterization of hydrochar produced at higher gasification temperatures revealed higher carbon content, thermal stability, alkalinity and structural deformity. The liquid products obtained from hydrothermal gasification of canola hull pellets also showed the presence of partially degraded or reformed organic compounds, which can be extracted as precursors for value-added chemicals.

Investigation into kinetic compensation effects for the production of hydrogen-rich gas during gasification of sub-bituminous coal char in varying gas environments

This study has focused on the evolution of kinetic parameters, i.e., Eapp and lnAapp and kinetic compensation effects (KCE) of char consumption and CO, CO₂, and H₂ formation during gasification of Collie coal char in varying gas environments (15%H₂O–Ar, 8%H₂O–Ar, and 0.4%O₂+8%H₂O–Ar). The instantaneous rate was obtained continuously during experiments by measuring the product gas composition using a quadrupole mass spectrometer. Observed variations of Eapp, lnAapp, and the extent of KCE suggest that the decrease in steam partial pressure from 15%H₂O to 8%H₂O surrounding the coal char particles appears to affect the path of CO₂ and H₂ formation from surface water-gas shift (WGS) reaction in 15%H₂O–Ar to char-H₂O heterogeneous reaction in 8%H₂O–Ar, at higher conversion (conversion >0.5). However, H₂ formation displays strong KCE and increased H₂ molar flux in 0.4%O₂+8%H₂O–Ar when compared to gasification of char with steam only (8%H₂O–Ar and 15%H₂O–Ar). In contrast, the introduction of 0.4%O₂ to 8%H₂O–Ar dominates the char gasification with only consumption of carbon active sites present on the char surface. That resulted in weak KCE for char consumption and decreased CO/CO₂ (molar flux ratio) compared to the gasification of char in 15%H₂O–Ar and 8%H₂O–Ar. Furthermore, the results indicate that the residual char obtained from the faster diffusion-controlled char-O₂ heterogeneous reaction in the 0.4%O₂+8%H₂O–Ar acts as an activated char precursor for subsequent kinetics-controlled char-H₂O heterogeneous reactions. This enhances the migration of H radicals generated from the H₂O molecule to the inner char matrix in 0.4%O₂+8%H₂O–Ar with an increased H₂ formation rate than gasification of char with steam only.

Hydrogen-rich gas production from disposable COVID-19 mask by steam gasification

Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H2, CO, CH4, and CO2 content of 38.89, 6.40, 21.69, and 7.34 vol%, respectively. The lower heating value of the product gas was 29.66 MJ/Nm3 and the cold gas efficiency was 74.55 %. This study showed that steam gasification can be used for the utilization of waste masks and the production of hydrogen-rich gas for further applications.