Waste furniture gasification using rice husk based char catalysts for enhanced hydrogen generation

Gasification of biomass for syngas production: Research update and stoichiometry diagram presentation

Gasification is a thermal process that converts organic materials into syngas, bio-oil, and solid residues. This mini-review provides an update on current research on producing high-quality syngas from biomass via gasification. Specifically, the review highlights the effective valorization of feedstocks, the development of novel catalysts for reforming reactions, the configuration of novel integrated gasification processes with an assisted field, and the proposal of advanced modeling tools, including the use of machine learning strategies for process design and optimization. The review also includes examples of using a stoichiometry diagram to describe biomass gasification. The research efforts in this area are constantly evolving, and this review provides an up-to-date overview of the most recent advances and prospects for future research. The proposed advancements in gasification technology have the potential to significantly contribute to sustainable energy production and reduce greenhouse gas emissions.

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.

Bio-oil and biochar production from Ageratum conyzoides using triple-stage hydrothermal liquefaction and utilization of biochar in removal of multiple heavy metals from water

Production of low-cost biomass and its utilization for producing cost effective and eco-friendly bioenergy as well as for removing heavy metals from water can be explored as an approach to meet the sustainable development goals. In light of the above-mentioned study, hydrothermal liquefaction (HTL) of Billy goat weed (BGW; Ageratum conyzoides) was carried out to produce bio-oil. In addition, the residual biochar from the HTL process was activated to obtain Act-BC and was further modified to produce MnO2-loaded biochar (Act-BC@MnO2-25%). The HTL of BGW was done at three different temperatures, i.e., 250 °C, 350 °C and 450 °C in a high-pressure batch reactor to maximize the bio-oil yield. Also, two different HTL methods i.e., single-stage HTL and triple-stage HTL of BGW were compared and discussed in detail. The bio-oil obtained via the triple-stage HTL was rich in carbon, hydrogen, and nitrogen. It also showed a higher heating value (HHV) and bio-oil yield (46%) than the single-stage. The residual biochar obtained at 450 °C (Act-BC) and MnO2 modified (Act-BC@MnO2-25%) were then tested to adsorb multiple heavy metal (i.e., Pb(II), Cd(II), Cu(II), and Ni(II)) from water. The kinetics data obtained from the adsorption experiment with Act-BC@MnO2-25% were well fitted to PSO kinetics model. The isotherm data were well aligned with the Langmuir model; the adsorption capacity of Act-BC@MnO2-25% was estimated to be 198.70 ± 11.40 mg g-1, 93.70 ± 6.60 mg g-1, 78.90 ± 7.20 mg g-1 and 30.50 ± 2.10 mg g-1 for Pb(II), Cd(II), Cu(II), and Ni(II), respectively. Furthermore, Act-BC@MnO2-25% remained active for metal ions absorption even after six consecutive uses. The result obtained from this study clearly demonstrates that the triple-stage HTL of BGW is a promising technology to achieve both remediation of metal-contaminated water and production of bioenergy.

Hydrogen-rich syngas production from biomass gasification using biochar-based nanocatalysts

Nanocatalysts are beneficial for tar elimination and syngas production during biomass gasification. In this study, novel biochar-based nanocatalysts loaded with Ni/Ca/Fe nanoparticles was prepared by one-step impregnation method for catalytic steam gasification of biomass. Results showed that the metal particles were evenly distributed with the particle size of less than 20 nm. With the introduction of nanoparticles, H₂ yield and tar conversion were obviously increased. Ni and Fe particles help to maintain the stability of the carrier microporous structure. Fe loaded biochar showed the best catalytic gasification performance, with 87% tar conversion and 42.46 mmol/g H₂ production. The catalytic effect of Fe was also higher than that of Ni and Ca if deducting the influence of carrier consumption. It demonstrated that Fe-loaded biochar was a promising catalyst candidate for hydrogen-rich syngas production from biomass gasification.

Sewage sludge steam gasification over bimetallic mesoporous Al-MCM48 catalysts for efficient hydrogen generation

This study explored the potential of steam gasification of sewage sludge over different temperatures (non-catalytic) and bimetallic (Ni-Fe and Ni-Co) mesoporous Al-MCM48 (3-5% Al basis). The higher temperature (800 °C) resulted in higher gas yield (36.74 wt%) and syngas (H₂ and CO) selectivity (35.30 vol% and 11.66 vol%). Moreover, catalytic approach displayed that the Al-MCM48 was effective support because the incorporation of nickel increased the efficiency of gasification reactions compared to HZSM-5 (30). It mainly comes from the presence of mesopores and higher surface area (710.05 m²/g) providing more reaction sites and higher stability (less coke formation). Furthermore, the addition of promoters such as Co and Fe allowed the formation of Ni-Fe and Ni-Co alloys, resulting in even higher gas yield and overall H₂ and CO selectivity due to the promotion of related reactions such as tar cracking, Boudouard, water gas shift and reforming and so on. Ni-Co alloy catalyst (10% Ni-5% Co/Al-MCM48) resulted in the highest H₂ (∼52 vol%) selectivity due to the enhanced Ni dispersion and synergy effect between Ni and Co. Moreover, the application of bi-metal alloy on Al-MCM48 showed no coke formation and significantly reduced CO₂ and hydrocarbon selectivity in the product gas. Overall, this study presented a promising solution for sewage sludge disposal in terms of clean H₂ generation, reduction in CO₂ and higher stability of metal based catalysts at the same time.

H2 generation from steam gasification of swine manure over nickel-loaded perovskite oxides catalysts

In this study, nickel-loaded perovskite oxides catalysts were synthesized via the impregnation of 10%Ni on XTiO₃ (X = Ce, Sr, La, Ba, Ca, and Fe) supports and employed in the catalytic steam gasification of swine manure to produce H₂-rich syngas for the first time. The synthesized catalysts were characterized using BET, H₂-TPR, XRD, HR-TEM, and EDX analysis. Briefly, using perovskite supports resulted in the production of ultrafine catalyst nanoparticles with a uniform dispersion of Ni particles. According to the catalytic activity test, the gas yield showed the increment as 10% Ni/LaTiO₃ < 10% Ni/FeTiO₃ < 10% Ni/CeTiO₃ < 10% Ni/BaTiO₃ < 10% Ni/SrTiO₃ < 10% Ni/CaTiO₃. Meanwhile, zero coke formation was achieved due to the oxygen mobility of prepared catalysts. Also, the increase in the H₂ production for the applied catalysts was in the sequence as 10% Ni/CeTiO₃ < 10% Ni/FeTiO₃ < 10% Ni/LaTiO₃ < 10% Ni/BaTiO₃ < 10% Ni/SrTiO₃ < 10% Ni/CaTiO₃. The maximum H₂ selectivity (∼48 vol%) obtained by10% Ni/CaTiO₃ was probably due to the synergistic effect of Ni and Ti on enhancing the water-gas shift reaction, and Ca on creating the maximum oxygen mobility compared to other alkaline earth metals doped at the A place of perovskite. Overall, this study provides a suitable solution for enhanced H₂ production through steam gasification of swine manure along with suggesting the appropriate supports to prevent Ni deactivation by lowering coke formation at the same time.

Torrefaction/carbonization-enhanced gasification-steam reforming of biomass for promoting hydrogen-enriched syngas production and tar elimination over gasification biochars

Biomass to H₂-enriched syngas is a very promising route to produce clean energy. This work proposed a new concept of promoting H₂-enriched syngas production and tar elimination through torrefaction/carbonization-enhanced gasification-steam reforming (T/CEGSR) of wheat straw (WS) over its gasification biochar materials (GCMs). WS torrefied at 280 °C (WS-280) subjected to gasification-steam reforming (GSR) over C-control presented the maximum gas yields and H₂/CO molar ratio (1.72). By introducing C[10 %O₂] for GSR of WS-280, the maximum cumulative gas yield (112.10 mmol/g_reactants), H₂ yield (59.91 mmol/g_reactants), and syngas yield (94.10 mmol/g_reactants) were achieved. Furthermore, C[10 %O₂] were superior to C-control, C[Ar] and C[CO₂] in light of carbon conversion efficiency, cold gas efficiency, and tar yield, reaching 97.45C%, 118.40 %, and 3.36 g/Nm³, respectively. Simply put, this study provides a newly sustainable and promising route by combining biomass torrefaction/carbonization with GSR using gasification biochar for enhancing H₂-enriched syngas production while reducing tar formation.

Production of biochar from crop residues and its application for biofuel production processes - An overview

A sustainable carbon-neutral society is imperative for future generations, and biochars and biofuels are inevitable choice to achieve this goal. Crop residues (CR) such as sugarcane bagasse, corn stover, and rice husk are promising sustainable resources as a feedstock for biochars and biofuels. Extensive research has been conducted on CR-based biochar production not only in environmental remediation areas but also in application for biofuel production. Here, the distribution and resource potential of major crop residues are presented. The production of CR-biochar and its applications in biofuel production processes, focusing on the latest research are discussed. Finally, the challenges and areas of opportunity for future research in terms of CR supply, CR-biochar production, and CR-biochar utilization for biofuel production are proposed. Compared with other literature reviews, this study can serve as a guide for the establishment of sustainable, economical, commercial CR-based biorefineries.

Morphological and heat transfer characteristics of biomass briquette during steam gasification process

The morphological evolution and heat transfer characteristics of biomass briquette greatly affect the directional regulation of target products during steam gasification process. In this work, a visual gasifier with an on-line temperature monitoring system was developed to investigate the coupling relationship between the morphological change and temperature distribution of biomass briquette. The gasification behaviors of biomass briquette at different temperatures and steam concentrations were comprehensively examined and compared. The shrinkage rate and heating rate of biomass briquette both reached the maximum at 1-2 min. The morphological evolution of biomass briquette in the heating process was shrinking particle mode, then changed to the shrinking core mode when the biomass temperature kept relatively stable. The high-quality syngas with a high H₂/CO ratio of 3.07 at 50 vol% steam concentration and 700 °C was obtained, which were idealized to synthesize other fuels/chemicals.

Recent advances of thermochemical conversion processes for biorefinery

Lignocellulosic biomass is one of the most promising renewable resources and can replace fossil fuels via various biorefinery processes. Through this study, we addressed and analyzed recent advances in the thermochemical conversion of various lignocellulosic biomasses. We summarized the operation conditions and results related to each thermochemical conversion processes such as pyrolysis (torrefaction), hydrothermal treatment, gasification and combustion. This review indicates that using thermochemical conversion processes in biorefineries is techno-economically feasible, easy, and effective compared with biological processes. The challenges experienced in thermochemical conversion processes are also presented in this study for better understanding the future of thermochemical conversion processes for biorefinery. With the aid of artificial intelligence and machine learning, we can reduce time-consumption and experimental work for bio-oil production and syngas production processes.