Non-catalytic Gasification Research Articles

Catalytic gasification of municipal solid waste using eggshell-derived CaO catalyst: An investigation of optimum H2 production, production distribution, and tar compounds

This study reports the optimum hydrogen (H2) production from municipal solid waste (MSW) via waste eggshell derived-CaO catalyst through gasification technology. The response surface model was applied to design the experiments and the data validation. Results showed that CaO catalyst had a better performance that enhanced 15 mol% more H2 production than non-catalytic gasification by mainly involving reaction temperature and catalyst loading as the critical parameters. Tar content was efficiently declined from 11.34 wt. % to 4.7 , wt. %, which ultimately elevated the H2 and syngas from 33.95 mol% to 51.27 mol% and 74.05 to 83.4674.05–83.46 wt. %, respectively. The model showed a strong interaction among the statistical parameters verified through the regression values; R2 = 0.990, P-value = 0.000005, respectively. Scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller techniques investigated the catalyst's structure hence; presented comparable results. From tar analysis, the aromatics were found as the dominant family followed by polycyclic aromatic, phenyls, aliphatic, aromatic heterocyclic, polycyclic, and aromatic ketones. Optimum H2 production of 51.27 mol% (with H2/CO ratio 2.82, LHV 9.47 MJ/Nm3, and H2 yield 22.74 mol kg-MSW−1) was produced which can be a better alternative to depleting fossil fuels and utilized for liquid fuel manufacturing and power generation.

Syngas Production from Protective Face Masks through Pyrolysis/Steam Gasification

The COVID-19 pandemic has caused a heavy expansion of plastic pollution due to the extensive use of personal protective equipment (PPE) worldwide. To avoid problems related to the entrance of these wastes into the environment, proper management of the disposal is required. Here, the steam gasification/pyrolysis technique offers a reliable solution for the utilization of such wastes via chemical recycling into value-added products. The aim was to estimate the effect of thermo-chemical conversion temperature and steam-to-carbon ratio on the distribution of gaseous products obtained during non-catalytic steam gasification of 3-ply face masks and KN95 respirators in a fluidized bed reactor. Experimental results have revealed that the process temperature has a major influence on the composition of gases evolved. The production of syngas was significantly induced by temperature elevation from 700 °C to 800 °C. The highest molar concentration of H2 gases synthesized from both types of face masks was estimated at 800 °C with the steam-to-carbon ratio varying from 0 to 2. A similar trend of production was also determined for CO gases. Therefore, investigated thermochemical conversion process is a feasible route for the conversion of used face masks to valuable a product such as syngas.

Catalytic gasification with ethanol: a novel valorization technique for scrap tires

Ethanol gasification of waste tires was investigated against pyrolysis in the presence of H-β zeolite and γ-Al2O3 catalysts. Non-catalytic gasification gave a much higher gas yield of 45.2% in comparison to a pyrolysis gas yield of 29% and increased the hydrogen content of the gas. Using a catalyst increased the gas yield during both pyrolysis and gasification from 29% to 34–35% and 50–52%, respectively. γ-Al2O3 was found to be more effective at catalyzing secondary pyrolysis reactions such as cracking, dehydrogenation, aromatization, and cyclization, especially when coupled with the excessive free radicals produced during ethanol gasification, resulting in a gas with 35 mol% hydrogen. H-β was found to enhance the formation of light alkenes such as propylene and ethylene during pyrolysis and gasification, respectively. The resultant syngas is suitable for use either as an energy alternative, or as feedstock for Fischer-Tropsch synthesis for the production of higher hydrocarbons.

Steam Gasification in a Fluidized Bed with Various Methods of In-Core Coal Treatment

The aim of this work is to study coal steam gasification with various methods of coal in-core treatment in FB using a newly developed thermodynamic calculation method. A calculational study of subbituminous coal steam non-catalytic gasification was carried out using four different methods of coal in-core treatment in single-vessel multisectional fluidized-bed gasifiers. A semi-empirical model based on the entropy maximization thermodynamic method and “restricted equilibria” based on previously obtained experimental data has been developed. Based on thermodynamic calculations, the effect of the leading thermochemical processes and operating parameters of the fluidized bed (temperature, fluidization number, steam/coal ratio feed rate) was revealed. New information was obtained regarding the composition of char and syngas at the gasifier outlet, the syngas heating value, and the cold gas efficiency of the steam gasification of Borodinskiy subbituminous coal char. The results indicate the possibility of significantly accelerating and improving non-catalytic steam gasification in fluidized bed gasifiers through the appropriate organization of in-core coal treatment. Based on the results obtained, the following recommendation is made—when designing multi-section and multi-vessel steam-blown gasifiers, the ratio of residence times should be set in favor of increasing the coal residence time in the steam-blown carbonization zone. Structurally, this can be achieved by increasing the volume and/or area of the steam-blown carbonization section (vessel).

H2-rich gas production from wood biomass air-steam gasification over a multifunctional Ni1.5Ca4.0Mn1.0Ox catalyst derived from biomaterial

Solid waste is a vexing and widespread issue, especially in urban and rural areas, where waste wood and eggshells generate significant pollution. Wood-based biomass features high-quality carbon neutral energy source properties, and discarded eggshells can be employed to develop a calcium-based multifunctional catalyst for wood gasification, thereby converting the waste into green hydrogen. In this work, an oxygen-rich vacancy (82.1%) Ni1.5Ca4.0Mn1.0Ox catalyst with a dual pore size nanostructure was derived from waste eggshell and demonstrated anti-coking, CO oxidation, CO2 fixation and high performance in H2-rich gas production during wood air-steam gasification. The mechanism for removing carbon deposition was based on the transfer of carbon species on Ni metal surfaces by using Mn and Ca substances. The behavior of wood non-catalytic gasification and catalytic gasification were quantitatively analyzed and compared on a time scale. Effects of temperature, duration time, and steam/biomass mass ratio were studied to determine the optimal gasification conditions. Catalytic gasification achieved an increase of 32.3% and 5.42 of H2 proportion and H2/CO as well as a decline of 8.51% of CO and 21.05% of CO2 contents when compared to non-catalytic air-steam gasification. This work might provide an innovative perspective on using waste to generate green hydrogen.

Transition metal chloride catalyzed methanol gasification in supercritical water: Experimental and DFT studies

Experimental analysis and density functional theory (DFT) calculation were performed on methanol gasification catalyzed by transition metal chlorides (CdCl2, CuCl2, FeCl3, and NiCl2) in supercritical water. The reaction temperatures (550–625 °C), residence times (6–60 s), and catalyst concentrations (0.00025–0.001 mol L−1) were experimentally investigated using a continuous reactor. Non-catalytic gasification of methanol produced the H2 yield of 0.64 mol mol−1 and gasification efficiency (GE) of 28.42 wt%, while the addition of 0.0005 mol L−1 transition metal chlorides contributed to significantly improved H2 yield and GE of 1.17–1.16 mol mol−1 and 61.13–106.16 wt% at 575 °C, respectively. The water molecules decrease the overall energy barrier of methanol decomposition pathways to promote methanol hydrogenation by forming intermolecular hydrogen bonds. Different transition metal cations form coordinate bond force with the O atom of the hydroxy group, causing a 20.5–41.1% reduction in the energy barrier of methanol oxidation and promoting methanol decomposition.

The Combined Impact of Ni-Based Catalysts and a Binary Carbonate Salts Mixture on the CO2 Gasification Performance of Olive Kernel Biomass Fuel

In the present work, the individual or synergistic effect of Ni-based catalysts (Ni/CeO2, Ni/Al2O3) and an eutectic carbonate salt mixture (MS) on the CO2 gasification performance of olive kernels was investigated. It was found that the Ni/CeO2 catalyst presented a relatively superior instant gasification reaction rate (Rco) compared to Ni/Al2O3, in line with the significant redox capability of CeO2. On the other hand, the use of the binary eutectic carbonate salt mixture (MS) lowered the onset and maximum CO2 gasification temperatures, resulting in a notably higher carbon conversion efficiency (81%) compared to the individual Ni-based catalysts and non-catalytic gasification tests (60%). Interestingly, a synergetic catalyst-carbonate salt mixture effect was revealed in the low and intermediate CO2 gasification temperature regimes, boosting the instant gasification reaction rate (Rco). In fact, in the temperature range of 300 to 550 °C, the maximum Rco value for both MS-Ni/Al2O3 and MS-Ni/CeO2 systems were four times higher (4 × 10−3 min−1 at 460 °C) compared to the individual counterparts. The present results demonstrated for the first time the combined effect of two different Ni-based catalysts and an eutectic carbonate salt mixture towards enhancing the CO production rate during CO2 gasification of olive kernel biomass fuel, especially in the devolatilization and tar cracking/reforming zones. On the basis of a systematic characterization study and lab-scale gasification experiments, the beneficial role of catalysts and molten carbonate salts on the gasification process was revealed, which can be ascribed to the catalytic activity as well as the improved mass and heat transport properties offered by the molten carbonate salts.

Supercritical water gasification of hyperaccumulators for hydrogen production and heavy metal immobilization with alkali metal catalysts

The high moisture content and heavy metal concentration of hyperaccumulator are the main bottlenecks of resource utilization. Supercritical water gasification technology was used to convert Sedum plumbizincicola (a hyperaccumulator of Zn and Cd) into hydrogen gas and to immobilize HMs into biochar. Homogeneous alkali metal catalysts such as NaOH, Na2CO3 and Ca(OH)2 were added to optimize the experimental conditions. The results showed that NaOH was effective in capturing CO2in-situ, thereby shifting the water-gas shift reaction equilibrium in the forward direction. And the increase of NaOH concentration had a significant promotion effect on hydrogen production. In the non-catalytic gasification of Sedum plumbizincicola, the highest hydrogen (1.5 mol/kg) and H2 selectivity (22.9%) with greater carbon gasification efficiency (19.3%) and lower H2 gasification efficiency (8.7%) of the gas products were obtained at 400 °C with 6 wt% material concentration for 20 min. However, NaOH at 5% mass fraction maximized hydrogen and H2 selectivity up to 7.5 and 98.2%, respectively. Alkali catalyst not only promoted the generation of hydrogen-rich bio-gas but also enhanced the immobilization efficiency of heavy metals. Compared to non-catalytic, when the addition amount of NaOH was 1 wt%, the Zn、Mn、Cd、Pb、Cr accumulated in biochar increased significantly for 76.8, 42.5, 80.8, 75.6 and 80.0%, respectively. This study highlights the remarkable ability of SCWG with alkali catalyst for hydrogen production and heavy metal stabilization.

Catalytic poppy seed gasification by lanthanum-doped cobalt supported on sepiolite

In this study, sepiolite as support material, was firstly used to synthesize a series of Co/xLa-SEP catalysts. Besides, a newly proposed biomass, poppy seed, was utilized in gasification for assessment of catalyst activity under various La loadings (0–10 wt% with a 2 wt% increment for each) and temperatures (550, 650, 750, 850 °C). The non-catalytic gasification resulted in the highest H2 concentration of 3.89 mol/kg poppy seed at 850 °C, whereas, the catalyst with 6 wt% La loading showed superior catalytic performance even at the much lower temperature of 650 °C, yielding 4.75 mol H2/kg poppy seed. Based on the results, char formation was almost utterly hindered in presence of 10 wt% La laoding at 850 °C, whereas a significant reduction of tar to 3.83 wt% was attained in corporation of 4 wt% La at 750 °C. The prepared catalysts were characterized by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) and Scanning Electron Microscopy (SEM). SEM images and BET data presented that the Co/6La-SEP catalyst exhibited smallest particle size and the highest surface area (251.05 m2/g).

Kinetic study on high-temperature gasification of medical plastic waste coupled with hydrogen-rich syngas production catalyzed by steel-converter ash

In order to dispose medical plastic waste (MPW) with aim of producing hydrogen-rich syngas, converter ash (CA) produced from the converter steelmaking process was used as the catalyst to promote MPW gasification coupled with the hydrogen-rich syngas production in a fixed-bed reactor at 900–1100 °C, and the kinetics on the MPW gasification were also analyzed based on Friedman and model-fitting method. The results indicated that the hydrogen-rich syngas was generated during the MPW high-temperature gasification due to the synergistic catalytic of the Fe2O3 and CaO in the CA. The CA had a significant catalytic effect on the reaction rates for the H2, CO and CH4 formation, whereas the steam had no significantly effect on the reaction mechanism for the H2, CO and CH4 formation during the MPW CO2 gasification. The kinetic models for the H2, CO and CH4 formation during the MPW non-catalytic CO2 gasification were in sequence as three-dimensional diffusion, chemical reaction (n = 1), and nucleation and growth (n = 1/2). However, the nucleation and growth (n = 2/3), chemical reaction (n = 0) and chemical reaction (n = 1) were the optimum models for the H2, CO and CH4 formation during MPW CO2 gasification in the presence of CA.

Hydrogen-rich gas production through supercritical water gasification of chicken manure over activated carbon/ceria-based nickel catalysts

In recent years, supercritical water gasification has attracted the attention of scientists and environmentalists not only as an alternative method for direct disposal of poultry manure, but also as an efficient hydrogen-rich gas generation process. In this study, by varying the temperature (375–450 °C), residence time (5–35 min), and feed concentration (2.5–3.5 wt%), some non-catalytic supercritical water gasification tests were designed and carried out in a stainless-steel U-type batch reactor to assess the optimum operational condition. To stimulate hydrogen production, catalytic experiments were conducted using the optimized condition (450 °C, 15 min, and 2.5 wt% of feedstock). The prepared catalyst supports and final nanocatalysts (Ni/Activated carbon, Ni/activated carbon-CeO2 nanorods) were then thoroughly characterized by various analytical instruments to verify the differences between the metal oxide-free and composite-like catalyst supports. Moreover, elemental analysis, gas and liquid chromatography were conducted to provide a deep understanding toward the impacts that composite-like catalyst support could have on diversity and quality of products. The experimental results revealed that, although in catalytic experiments the H2 yields were higher than those recorded in non-catalytic experiments, highest hydrogen selectivity of 36.42 % could be achieved when Ni/activated carbon-CeO2 nanorods were employed.

Sustainability assessment of biomethanol production via hydrothermal gasification supported by artificial neural network

Global warming and climate change urge the deployment of close carbon-neutral technologies via the synthesis of low-carbon emission fuels and materials. An efficient intermediate product of such technologies is the biomethanol produced from biomass. Microalgae based technologies offer scalable solutions for the biofixation of CO2, where the produced biomass can be transformed into value-added fuel gas mixtures by applying thermochemical processes. In this study, the environmental and economic performances of biomethanol production are examined using artificial neural networks (ANNs) for the modelling of catalytic and noncatalytic hydrothermal gasification (HTG). Levenberg-Marquardt and Bayesian Regularisation algorithms are applied to describe the thermocatalytic transformation involving various types of feedstocks (biomass and wastes) in the training process. The relationship between the elemental composition of the feedstock, HTG reaction conditions (380 °C–717 °C, 22.5 MPa–34.4 MPa, 1–30 wt% biomass-to-water ratio, 0.3 min–60.0 min residence time, up to 5.5 wt% NaOH catalyst load) and fuel gas yield & composition are determined for Chlorella vulgaris strain. The ideal ANN topology is characterised by high training performance (MSE = 5.680E-01) and accuracies (R2 ≥ 0.965) using 2 hidden layers with 17-17 neurons. The process flowsheeting of biomass-to-methanol valorisation is performed using ASPEN Plus software involving the ANN-based HTG fuel gas profiles. Cradle-to-gate life cycle assessment (LCA) is carried out to evaluate the climate change potential of biomethanol production alternatives. It is obtained that high greenhouse gas (GHG) emission reduction (−725 kg CO2,eq (t CH3OH)−1) can be achieved by enriching the HTG syngas composition with H2 using variable renewable electricity sources. The utilisation of hydrothermal gasification for the synthesis of biomethanol is found to be a favourable process alternative due to the (i) variable synthesis gas composition, (ii) heat integration, and (iii) GHG emission mitigation possibilities.

Effects of Lewis acid on catalyzing gasification of sewage sludge and model compounds in supercritical water

In this work, we investigated how different types and concentrations of Lewis acids effect gas yield and composition from supercritical water gasification (SCWG) of dewatered sewage sludge (DSS). Furthermore, the catalytic mechanism was investigated using AlCl3 as a representative Lewis acid catalyst. Results showed that non-catalytic gasification of DSS produced a hydrogen yield of 0.13 mol/kg organic matter (OM) and total gas yield of 4.82 mol/kg OM; while the addition of 10 wt% Lewis acid resulted in a significantly improved H2 and total gas yield of 0.77–7.76 mol/kg OM and 7.57–22.88 mol/kg OM, respectively. In addition, the Lewis acids tested herein depicted the following activity trend: AlCl3＞FeCl3＞NiCl2＞ZnCl2. The required temperature for generating hydrogen from SCWG of DSS was greatly reduced when AlCl3 was present during the heating process. Furthermore, AlCl3 significantly increased the hydrogen yield from SCWG of the model compounds. Finally, AlCl3 catalyzed SCWG of guaiacol and glycerol showed the best hydrogen selectivity.

Hydrogen-rich energy recovery from microalgae (lipid-extracted) via steam catalytic gasification

Identifying and tackling indispensable developments in microalgae-based bio-economy should be a priority to unravel the contentious water-food-energy-environment nexus that algae inhabit. This research investigated the catalytic and non-catalytic steam gasification of two types of lipid-extracted microalgae biomasses, Chlorella vulgaris and Spirulina platensis in a thermogravimetric analyzer coupled with online mass spectrometry. A hybrid-functional mixture consisting of CaO naturally derived from waste eggshell as catalyst and sorbent, Ni as catalyst and Y2O3 as support was employed during the gasification that mainly generated H2, CO and CO2. The varied CaO loading (10 to 50 wt%) showed an evident effect on the overall gasification of lipid-extracted microalgae biomass, indicating an optimal CaO loading of 40 wt% for Ni-CaO-Y2O3 mixed materials which enabled 400.81 and 324.93 mL g−1 of H2 yield, with maximum purity of up to 53.25 and 41.82 vol% in gaseous product for Chlorella vulgaris and Spirulina microalgae residues, respectively. The addition of Ni, Y2O3 in mixed form (Ni-CaO, Ni-CaO-Y2O3, CaO-Y2O3 and Ni-Y2O3) drastically enhanced H2 yield and its purity. Ni-CaO produced the maximum H2 yield and purity of 497.29 and 435 mL g−1, and 63.15 and 45.78 vol% for Chlorella vulgaris and Spirulina platensis, respectively.

Towards enhanced catalytic reactivity in CO2-assisted gasification of polypropylene

The role of catalyst (Ni/Al2O3) position on improved gasification of polypropylene (PP) in CO2 atmosphere using a fixed bed reactor at 900 °C was examined and the results compared with non-catalytic gasification. The catalytic gasification included in-situ and quasi-in-situ (with feedstock located close to but not directly in contact with the catalyst) configuration. Results are reported on the evolutionary behavior and yield of carbon monoxide (CO), hydrogen (H2), hydrocarbons (CmHn) and total syngas. Compared to non-catalytic gasification, in-situ, and quasi-in-situ catalytic gasification produced higher H2 by 120.5% and 137.1%, higher CO by 38.2% and 24.0%, higher CmHn by 57.1% and 98.2%, and higher total syngas by 44.1% and 43.8%, respectively. CO2-assisted gasification of PP with Ni/Al2O3 catalyst significantly enhanced the gases evolution rate and improved the syngas yield. Results revealed better catalytic activity with quasi-in-situ configuration in the thermal decomposition of PP into H2 and CmHn than in-situ catalytic configuration. However, in-situ catalytic configuration provided more CO under similar gasification conditions. Approximately 0.8, 1.1 and 1.0 kg of CO2 could be consumed per kg of PP feedstock to generate syngas energy yield of 27.5, 43.1 and 48.1 MJ with non-catalytic, in-situ and quasi-in-situ catalytic configuration, respectively, suggesting efficient utilization of both CO2 and PP waste for clean and efficient energy production.

Catalytic mechanism study on the gasification of depolymerizing slag in supercritical water for hydrogen production

Supercritical water gasification technology can realize efficient conversion of biomass, coal and other organics into hydrogen rich gas. But the efficiency of non-catalytic gasification at relative low temperature is not high. Besides, as for catalytic gasification, catalysis mechanism is complex. Thus how to improve efficiency and master the catalysis mechanism is a challenging issue. In this thesis, supercritical water gasification of depolymerizing slag experiments with the catalysis of different kinds of catalysts are conducted and the catalysis mechanism is analyzed. The results indicate that catalyst mechanism of K2CO3 is that it can promote the swelling and hydrolysis of lignocellulose and increase the amounts of phenolic intermediates. Ru/Al2O3 presents some different catalytic properties. It facilitates hydrogenation reaction of hydrolysis products, ring-opening reaction and the cleavage of carbon-carbon bonds then enhances gasification degree and increases gasification efficiency. Moreover, the binary catalyst displays a good synergic effect and the catalytic activity is higher than that of any single catalyst since these two catalysts promote various gasification stages. The gasification efficiency and hydrogen yield increase 13.22 mmol g−1 and 66.46% respectively with the synergic catalyst of K2CO3 and Ru/Al2O3.

Experimental and thermodynamic study of banana peel non-catalytic gasification characteristics

The Gasification performance of banana peel was examined in a fixed bed reactor. Effect of temperature, steam to carbon ratio (S/C), drying treatment on syngas composition, gas yield, CO2 selectivity and carbon conversion efficiency (CCE) were investigated. The influence of temperature and S/C on hydrogen production was investigated by thermodynamic analysis. The transient characteristics of banana peel steam gasification were investigated by monitoring the evolutionary behavior of syngas production. An increase in S/C can lead to an increase in the selectivity of CO2, but excess steam (S/C > 21.7) causes a decrease in H2 yield and CCE. The increase of temperature is beneficial to the increase of CCE, but which leads to a decrease in CO2 selectivity. When S/C = 27.1, the effect of temperature on H2 yield can be divided into CCE control region and CO2 selectivity control region. At temperature < 1023 K, H2 yield is more sensitive to the changes of CCE. While at temperature > 1023 K, CO2 selectivity has a more significant effect on H2 yield. When S/C = 21.7 and temperature is 1023 K, the yield of H2 produced from the fresh banana peel gasification reaches the maximum value (76.1 ml/g).

Hydrogen production from steam gasification of corn straw catalyzed by blast furnace gas ash

A lab scale gasifier was built to perform the gasification experiment. The effects of temperature and steam flow on the process were investigated, and the effects of the addition of blast furnace gas ash (BFGA) on product composition, the value of H2/(CO + CO2), the lower heating value (LHV) of product gas, and productivity are summarized. The experimental results clearly indicate that the addition of BFGA in the steam gasification of corn straw pellets effectively enhances the ability of the downdraft gasifier to produce hydrogen-rich gas. Compared with the non-catalytic gasification process, the addition of BFGA promotes the formation of H2, inhibits the generation of methane, CH4, and other hydrocarbon gases, CnHm, and increases the H2/(CO + CO2) ratio. Unlike the process without the BFGA, the LHV of the product gas with BFGA increases with increasing temperature. When the water vapor volume was 0.75 kg/h, the gas production rate was the same at 850 °C with BFGA and at 950 °C without ash gas. The addition of BFGA clearly leads to a significant improvement in the ability of gasifiers to produce hydrogen-rich gas.

Change in Catalytic Activity of Potassium during CO2 Gasification of Char

Potassium (K)-catalyzed CO2 gasification of lignite char was studied with a particular focus on the change in catalyst activity with the char conversion (X) at 800–900 °C. Char samples were prepared from an Indonesian lignite by a sequence of complete removal of inherent metallic species and mineral matter, K-loading by ion-exchange, and pyrolysis. The catalytic activity of K (kcat′) was defined as the rate of catalytic gasification (after elimination of the rate of non-catalytic gasification and that of K volatilization from total mass release rate from char) per amount of K retained by the gasifying char. kcat′ increased by a factor of 5–20 with X over its range up to 0.98–0.99, depending on the initial K concentration in the char (mcat,0), ranging 0.16–1.4 wt %-daf. Such significant increase in kcat′ was due to the change in not the intrinsic reactivity of char but its porous nature, that is, the size and volume of pores that retained the K catalyst. At X < 0.4, the entire portion of the K catalyst was...

Effects of Ionic Liquid-Assisted Pretreatment of Heavy Metal-Contaminated Biomass on the Yield and Composition of Syngas Production Using Noncatalytic and Catalytic Pyrolysis and Gasification Processes

In this research, noncatalytic and catalytic pyrolysis and gasification of heavy metal-contaminated biomass (HMCB)—untreated and pretreated using a low-cost ionic liquid (IL, triethylammonium hydro...