Fixed-bed Reactor Research Articles

3D-printed devices for continuous-flow lithium recovery of brines

Adsorption processes were widely used in the recovery of lithium from salt lakes. Fixed-bed continuous flow reactors were mainly used in adsorption due to their simple structure and stable reaction. 3D printing, due to its ability to greatly reduce the packing and fixed-bed reactor design cycle and cost, was gradually becoming as one of the key technologies for intelligent manufacturing of fixed beds. This work utilizes the advantages of digital preparation by 3D printing to address the low elution efficiency and adsorption capacity of titanium-based lithium-ion sieves (Ti-LIS) in fixed-bed lithium recovery. 3D printed fixed bed packing with high adsorption capacity were prepared using an in-situ growth strategy, acidic gel and reactor design were utilized to achieve efficient elution of Ti-LIS. The dynamic adsorption showed that the adsorption capacity of 3D printed fixed bed packing could reach 16 mg·g−1 and the elution efficiency can be increased from 78 % to 95 % with the same amount of acid.

Intensified reforming reactor for blue hydrogen and nitrogen production

The development of Chemical-looping Reforming (CLR) for blue hydrogen production requires a precise reactor design and control to achieve optimal efficiency and operability. This study proposes a 1D heterogeneous model for a CLR fixed-bed reactor, targeting the production of blue hydrogen and nitrogen. Validation against experimental data confirms the model’s accuracy and reliability. A comprehensive sensitivity analysis highlights reactor variables, including active metal content in the oxygen carrier, steam-to-methane ratio, and molar flow rates during reduction and reforming stages, as key variables in determining reactor performance. Optimizing these variables is crucial for process intensification and enhancing hydrogen production efficiency. Under optimal conditions, the reactor yields nitrogen with a concentration above 98% during the oxidation stage and hydrogen with a 66.7% concentration during the reforming stage. Moreover, the CLR reactor operates autothermally and reaches a hydrogen production efficiency of 63.6%, prior to any further purification. The study concludes with a discussion of the reactor’s challenges and opportunities, laying the groundwork for potential future research and advancements in the field.

Enhanced degradation of 2,4-dichlorophenol in groundwater by defective iron-based metal-organic frameworks: Role of SO3[rad]− and electron transfer

The purposeful formation of crystal defects was regarded as an attractive strategy to enhance the catalytic activity of Fe-MOFs. In this study, the pyrolytic hydrochloric acid-modulated MIL-101-NH2 (P250HMN-2) was fabricated for the first time, and the important role of pyrolysis in the formation of crystal defects was confirmed. PDS was introduced as an enhancer for the P250HMN-2/Na2SO3 system. Without pH adjustment, 99.7 % of 2,4-DCP was removed by the P250HMN-2/Na2SO3/PDS system in 180 min. The catalytic performance of P250HMN-2 improved 2.5-fold than that of MIL-101-NH2. It was found that the high density of Fe-CUSs on P250HMN-2 were the major active sites, which could efficiently react with SO32− to generate ROS through electron transfer. The results of quenching experiments, probe tests, and EPR tests indicated that SO3−, SO4−, 1O2, OH, and SO5− were involved in the 2,4-DCP degradation process, with SO3−, SO4−, and 1O2 playing major roles. Moreover, P250HMN-2 could effectively degrade 2,4-DCP for 148 h in a fixed-bed reactor with excellent stability and reusability, indicating a promising catalyst for practical applications.

Research on high-carbon ether-based oxygen additives: Catalytic transformation of 2-methylfuran and furfural to ethers via CuMgAlOx catalysts

The surge in aviation fuel consumption has intensified environmental concerns, driving research efforts towards discovering oxygen-enriched additives that can boost their performance. This investigation employs 2-methylfuran and furfural as precursors, undergoing catalytic conversion into high-performance high-carbon ethers. The study initiates by employing Amberlyst-15 resin as a catalyst, converting 2-methylfuran and furfural into a high-carbon polymer (1A). A continuous polymerization process in a fixed-bed reactor highlights the exceptional stability of Amberlyst-15, maintaining a conversion rate of approximately 70 % over 140 h. A kinetics model elucidates the temperature-dependent dynamics of the polymerization reaction. Following this, the polymer undergoes hydrogenation (HDO) using CuMgAlOx catalyst, yielding an ether compound (2A) with a remarkable selectivity of 95.7 % and a carbon yield of 95.5 %. Characterization techniques reveal uniform elemental distribution and a high abundance of mesopores in the CuMgAlOx catalyst, substantiating its superior hydrogenation efficiency. Notably, even after six cycles, the CuMgAlOx catalyst retains an impressive 94.8 % polymer conversion rate, underscoring its exceptional stability.

NiO–Ca9Co12O28 bifunctional phase change catalysts for biomass pyrolysis to hydrogen-rich syngas

In this study, the preparation of hydrogen-rich gases from improved pyrolysis-catalytic reforming system by industrial solid waste calcium carbide slag was investigated in a fixed-bed reaction system. The differences in biomass pyrolysis gas compositions and yields over the bifunctional phase change catalyst NiO–Ca9Co12O28 with different Ni doping ratios, pyrolysis temperatures, and calcium carbide slag doping ratios have been investigated, and a model for the mechanism of the redox reaction over the NiO–Ca9Co12O28 catalyst is proposed at the same time. The results of the study indicated that the maximum hydrogen production is 447.23 mL/gbiomass at 600 °C when the mass ratio of bamboo to calcium carbide slag is 5:9, which is 549.29% higher than that of pyrolysis of bamboo alone. The hydrogen volume concentration increased from 17.93% to 63.78%. This study provides a green and efficient route for high-value conversion of biomass and adsorption-enhanced reforming of solid waste for hydrogen production.

Critical role of transport phenomena in the performance of a catalytic fixed bed reactor for the CO2 hydrogenation to CH4 evaluated by modeling and simulation

CO2 hydrogenation with renewable hydrogen enables the production of CH4 to be used as energy carrier (CO2 + 4H2 ⇆ CH4 + 2H2O). Steady state 1D pseudo-homogeneous and heterogeneous models, in the absence or presence of mass and energy transport in the axial direction of the reactor and inside the solid phase, are considered to simulate a non-isothermal fix bed reactor. Numerical strategies for solving these models in Matlab R2022b are discussed. The pseudo-homogeneous plug-flow model is not able to describe the experimental results irrespective of the global heat transfer coefficient considered. The inclusion of mass and energy transport in the reactor axial direction is crucial for describing the experimental data. The inclusion of mass and heat transport inside the solid phase by the heterogeneous model enables the best fitting. This work provides a valuable modeling tool for future industrial-scale reactor design.

Thermodynamic and kinetic study on the catalysis of tributyl aconitate by Amberlyst-15 in a cyclic fixed-bed reactor

Abstract Tributyl aconitate is a new type of alternative plasticizer to phthalates. Amberlyst-15 was used to catalyze the esterification of aconitic acid and n-butanol for the preparation of tributyl aconitate in a cyclic fixed-bed reactor. The influence of the reaction conditions on the conversion was investigated. The results showed that the conversion of aconitic acid increased significantly with the rise of temperature and catalyst loading. The reaction conditions were optimized as: temperature: 115 °C; initial mass ratio of AA and n-butanol: 1:4; catalyst loading: 25 %; reaction absolute pressure: 85 kPa; volume flow rate: 30 mL min−1. Thermodynamics and kinetics of the reaction was studied. The non-ideality of the reaction system was rectified using the UNIFAC group contribution method. The kinetic process was simulated using the pseudo-homogeneous (PH) model, Eley-Rideal (E-R) model, and Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. The results revealed that the E-R model exhibited superior suitability in simulating the kinetic process.

Synergetic effects of Al addition on the performance of CoFe2O4 catalyst for hydrogen production and filamentous carbon formation from direct cracking of methane

Improving methane catalytic decomposition process was deemed an effective approach for hydrogen production. Here, a novel catalyst AlxCo1-xFe2O4 with a variable aluminum content was synthesized via a co-precipitation route for the direct cracking of methane. The catalytic activity of AlxCo1-xFe2O4 was performed in a fixed bed reactor at temperature of 800°C and 20 mL/min of fed gas. A sequence of characterizations, including SEM, BET, XRD, XPS, Raman and TGA for fresh and spent catalysts, was exploited to examine the influence of Alx content on the morphology, porosity, structure, chemical composition, and cation distribution of AlxCo1-xFe2O4. As the Alx content increased in AlxCo1-xFe2O4 their morphology became more fractal and decreased in particle size, lattice parameter, lattice size, while their pore surface increased. Further cation re-distributions from octahedral to tetrahedral sites as Fe3+ and Al3+ relocated in the Tetrahedral site and Oxygen lattice decreased as observed from Raman and XPS results. Catalytic activity studies showed that Alx content of 0.6 in AlxCo1-xFe2O4 lead maximum methane conversion up to ∼ 91.10 % and hydrogen formation rate of 1.780 ×10-3 mol H2 g-1 s-1. The catalytic activity behavior was explained in correlation with the characteristics of spent catalysts.

Comparing the performance of fluidized and fixed granular activated carbon beds as cathodes for microbial electrosynthesis of carboxylates from CO2

Microbial electrosynthesis (MES) can use renewable electricity to power microbial conversion of carbon dioxide (CO2) into carboxylates. To ensure high productivities in MES, good mass transfer must be ensured, which could be accomplished with fluidization of granular activated carbon (GAC). In this study, fluidized and fixed GAC bed cathodes were compared. Acetate production rate and current density were 42 % and 47 % lower, respectively, in fluidized than fixed bed reactors. Although similar microbial consortium dominated by Eubacterium and Proteiniphilum was observed, lowest biomass quantity was measured with fixed GAC bed indicating higher specific acetate production rates compared to fluidized GAC bed. Furthermore, charge efficiency was the highest and charge recovery in carboxylates the lowest in fixed GAC beds indicating enhanced hydrogen evolution and need for enhancing CO2 feeding to enable higher production rates of acetate. Overall, fixed GAC beds have higher efficiency for acetate production in MES than fluidized GAC beds.

Artificial Neural Network and Response Surface Methodology for Predicting and Maximizing Biodiesel Production from Waste Oil with KI/CaO/Al2O3 Catalyst in a Fixed Bed Reactor.

Biodiesel from waste oil is produced using heterogeneous catalyzed transesterification in a FBR. KI/CaO/Al2O3catalyst was prepared through the processes of calcination and impregnation. The novel catalyst was analyzed with XRD, SEM, and EDX. The DoEmethod resulted in a total of 20 experimental runs. The significance of 3 reaction parameters, namely catalyst bed height, methanol to waste oil molar ratio, and residence time, and their combined impact on biodiesel yield is investigated. Both the artificial neural network (ANN) based on AIand the Box-Behnken design (BBD) based on response surface methodology (RSM) were utilized in order to optimize the process conditions and maximize the biodiesel production. A quadratic regression model was developed to predict biodiesel yield, with a correlation coefficient (R) value of 0.9994 for ANN model and a coefficient of determination (R2) value of 0.9986 for BBD model. The maximum amount of biodiesel that can be produced is 98.88% when catalyst bed height is 7.87 cm, molar ratio of methanol to waste oil is 17.47:1, and residence time is 3.12 h. The results of this study indicate that ANN and BBD models can effectively be used to optimize and synthesize the highest %yield of biodiesel in a FBR.

Biogas dry reforming over Li–Ni–Al LDH-derived catalysts

Biogas dry reforming or dry reforming of methane (DRM) is an alternative to produce hydrogen, in the context of development of sustainable routes for energy production, since this route uses CH4 and CO2, two greenhouse gases as reactants. However, the deactivation of catalysts due to carbon deposition and sintering is the main drawback of this reaction. In this work, with the aim of minimizing carbon formation and sintering during DRM, the effect of lithium as a promoter in catalysts Ni–Al derived from layered double hydroxides was investigated. The catalysts were prepared by co-precipitation and characterized by different techniques: BET surface area (SBET), X-ray diffraction (XRD), temperature-programmed reduction (TPR), CO2 and H2 temperature-programmed desorption (CO2-TPD and H2-TPD), Scanning Electron Microscopy (SEM-EDS), temperature-programmed oxidation (TPO). The catalytic tests were carried out in a fixed bed reactor using a synthetic biogas (60% CH4 and 40% CO2) in the temperature range of 500–750 °C. The incorporation of Li into the Ni–Al-LDH changed the reducibility and basicity of the catalysts. The Li2 sample containing an intermediary amount of Li (5 wt%) showed the highest reduction temperature and highest density of basic sites, which resulted in the smallest Ni crystallite size before and after the reactions. As a result, this catalyst presented the greater resistance to sintering and a lower rate of carbon produced. For the reaction carried out at 700 °C, only the Li2 catalyst remaining active during the test and reaching a maximum of 80% and a final CH4 conversion of 54% after 480 min of reaction, whereas CO2 conversion was higher than 90%. All other samples deactivated at different rates due to carbon deposition and sintering.

Degradation of Tetracycline through peroxymonosulfate activation with Co/Fe-LDH modified magnetic hydrochar: Synergistic effect and low toxicity

In this work, 2LDH-CoFe2O4@BHC catalyst was prepared by modifying magnetic corncob-based hydrochar (CoFe2O4@BHC) with Co/Fe layered double hydroxide (Co/Fe-LDH), which was used to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. 2LDH-CoFe2O4@BHC demonstrated effective activation of PMS and rapid removal of TC (100 %) within 10 min by leveraging structural modulation and synergistic interactions among multiple components. In contrast, BHC (26.02 %), CoFe2O4 (59.25 %), and CoFe2O4@BHC (61.88 %) presented poor removal efficiency. Furthermore, it was shown that both the free radicals (SO4•-) and non-free radicals (1O2) were essential in the degradation process, and the catalytic mechanism was revealed to be a synergistic process with the characterization results from in-situ Raman, electrochemical characterization, and X-ray photoelectron spectroscopy (XPS). The catalytic performance of 2LDH-CoFe2O4@BHC was also evaluated using a self-developed fixed-bed reactor, demonstrating its strong stability and resistance to interference during long-term operation. The potential degradation pathway of TC in the 2LDH-CoFe2O4@BHC + PMS system was suggested based on the quadrupole time-of-flight mass spectrometry (QTOF/MS) findings. It was found that the toxicity of the intermediates produced by TC degradation significantly reduced. This study presented an insight for the decomposition of organic pollutants by synthetic biochar-loaded catalysts.

Assessing bioenergy prospects of algal biomass and yard waste using an integrated hydrothermal carbonization and pyrolysis (HTC–PY): A detailed emission–to–ash characterization via diverse hyphenated analytical techniques and modelling strategies

Hydrothermal carbonization (HTC) presents a promising method for converting carbonaceous waste into renewable fuels, facilitating energy recovery. This study focuses on the HTC pretreatment of microalgae (Chlorella sorokiniana) and yard waste, examining their physicochemical structural changes, component migration, and potential for valorization via integrated HTC and pyrolysis processes. HTC notably enhances the carbon content while reducing oxygen and nitrogen levels in these feedstocks, producing a clean solid fuel with high energy density. The study investigates the pyrolytic behavior of hydrochars and their blends using different analytical techniques, kinetic modeling, and fixed–bed reactor experiments. The blends with 90% and 70% of microalgae hydrochar (CSH) exhibited the most significant synergistic effects during co–pyrolysis, evident in its devolatilization behaviors and reduced activation energies. Integrating artificial neural networks and response surface methodology models facilitated optimization of pyrolysis parameters and accurate prediction of bio–oil, biochar, and gas yields. The analytical techniques enabled characterization of pyrolysis products, revealing notable changes in bio–oil and biochar compositions, suggesting potential enhancements. The study comprehensively evaluates the HTC–pyrolysis approach’s potential for converting microalgae and lignocellulosic biomass into eco–friendly biofuels for industrial applications.

Carbon dioxide conversion to fuel over alumina-supported ruthenium catalysts

In this study, ruthenium-based catalysts were prepared for CO2 hydrogenation. Incipient-wetness-impregnation of the alumina-support with ruthenium (III) nitrosyl nitrate solution to achieve 0.5 wt% Ru loading on supports was used to prepare these catalysts. Potassium (0–3 % wt%) was used to further promote the catalysts. TPR, CO2-TPD, XRD, TEM, XPS, SEM, and EDS analyses were used to characterize catalyst properties. The hydrogenation of CO2 catalytic tests were conducted and the effect of operating conditions (temperature, pressure, and space velocity) were investigated. These studies were conducted in a tubular fixed-bed reactor. The CO2 conversion over these catalysts was found to be low and the dominating product observed was CH4 with a small amount of C2+ forming when K was added to the catalyst. The optimum potassium loading for improved C2+ product yield over Ru/Al2O3 was 1%K for CO2 hydrogenation.

Selective oxidation of methyl glycolate to methyl glyoxylate with molecular oxygen catalyzed by VOx/γ-Al2O3

The selective oxidation of methyl glycolate (MG) to methyl glyoxylate (MGO) using molecular oxygen in a fixed-bed reactor represents a greener and more efficient alternative to the traditional batch processing for producing this important fine chemical and intermediate. Despite its potential, detailed understanding of this catalytic reaction is still limited. In our study, VOx/γ-Al2O3 catalysts were identified as effective for the reaction, but their performance strongly depended on the structure of VOx species. The optimal catalyst with nearly monolayer dispersed VOx achieved a high MG conversion of 91% and an MGO selectivity of 71%, alongside maintaining stability for 300 h without noticeable deactivation. At a low V loading of 0.6%, isolated VOx species were formed, exhibiting the highest turnover frequency (TOF) but the lowest MGO selectivity. Increasing the V loading to 3.9% resulted in a blend of less polymeric and isolated VOx species, which decreased the TOF but enhanced MGO selectivity to 59%. With the V loading ranging from 5% to 6.2%, monolayer dispersed VOx became dominant, yielding a lower TOF and the highest MGO selectivity. A further increase in V loading caused the emergence of crystalline V2O5, which seemed to act as a bystander. Moreover, the redox cycles of V4+ and V5+ over the VOx/γ-Al2O3 catalyst played an important role in the selective oxidation of MG to MGO, while the overoxidation of MG to CO2 might take place through the V3+/V4+ redox pairs, the extent of which was determined by the structure of VOx species. These insights are crucial for developing high-performance VOx-based catalysts for the production of MGO through the selective oxidation of MG.

Co-pyrolysis of coal and biomass blends: Impact of pyrolysis temperature and biomass blending on thermal stability of coal, and composition of pyrolysis products

The study investigates the thermal pyrolysis of coal and co-pyrolysis of the coal-sawdust blend (100% blend) in a fixed-bed reactor. The pyrolysis od coal and sawdust was performed at 773 K, 823 K, and 873 K temperature and 30 K min−1 heating rate under nitrogen purge gas (300 mL min−1). Co-pyrolysis coal and biomass was performed at 50%, 100%, and 200% blends at 873 K temperature. The pyrolysis and co-pyrolysis products such as liquid and gas was analysed and compared. Coal pyrolysis resulted higher coal char generation with negligible yield of liquid and gas compared to sawdust. However, 100% co-pyrolyzed blend resulted in higher oil yield % with the increase in temperature from 773 to 873 K with conversion % at 37.35% at 873 K temperature. It was confirmed that the increase in biomass blending percentage with coal, the conversion % increased to 92.8% for the 200% blend. GC/MS characterization of oil from 100% and 200% blended samples revealed that alkane is the main component along with a remarkable Cp value of 1.094 kJ kg−1 K−1 and 0.271 kJ kg−1 K−1 obtained at 823 K and 873 K reaction temperatures respectively. The pyrolysis oil obtained at 873 K at higher biomass to coal blended condition contained higher aromatic compounds. Certain rare comp compounds such as 1-Methyl cyclopropane methanol, 3, 3’- Thiodipropanol, 3- Trans-(1,1-Dimethylethyl)-4, Cis, Methoxycyclohexane-1-ol, 1, 1 -Dimethyl-1-Sinacyclobutane, Octadecane, 2,2,4,15,17,17-Hexamethyl-7, 12-Bis (3, 5,5-Trimethylhexyl), 1,4:3,6-Dianhydro-Alpha-D-Glucopyranose, Hexacosyl acetate and 1,2-Benzenediol, 4-Methyl- present in the copyrolysis oil was also a significant observation in this study.

Conversion of beechwood organosolv lignin via fast pyrolysis and in situ catalytic upgrading towards aromatic and phenolic-rich bio-oil

Lignin, an abundant renewable biopolymer found in plant cell walls, is enriched in phenolic units within its complex molecular structure. Unlocking its potential as alternative feedstock in (bio)refining has posed a long-standing challenge, even though it holds immense promise for replacing fossil-derived phenolic and aromatic compounds. This study focuses on fast pyrolysis as effective thermochemical depolymerization method of lignin, coupled with the in situ catalytic upgrading aiming to produce valuable bio-oil enriched in dealkoxylated (alkyl)phenolic and aromatic compounds. Lignin was isolated via the organosolv process from beechwood sawdust (hardwood biomass). Various acidic aluminosilicate catalysts (e.g., zeolites, such as ZSM-5, Beta and USY, and amorphous silica alumina) were applied, having different Si/Al ratio, porous and acidic properties. Fast pyrolysis experiments were conducted on a fixed-bed bench-scale reactor at two distinct temperatures (500 and 600 °C), employing different contact times and lignin-to-catalyst ratios. Non-catalytic pyrolysis experiments revealed that higher temperature, significantly influences bio-oil’s composition and yield, resulting in the conversion of initially formed alkoxy-phenols to alkyl-phenolic compounds, reaching a 47% relative concentration at 600 °C, while also yielding high amount of bio-oil up to 43 wt%. Among the catalysts tested, zeolite ZSM-5 (Si/Al=40) proved to be the most efficient, shifting the chemical profile of bio-oil from phenolic to aromatic (mainly BTX) with relative concentration of 57%, owing to its unique microporous structure and acidity. Depending on the catalyst type, a balance between BTX monomer aromatics and naphthalenes was observed. Lignin, as well as the obtained products (bio-oil, non-condensable gases, char/coke-on-catalyst) were thoroughly characterized using various analytical techniques. The catalytic upgrading results were associated with the physicochemical properties of the catalysts, providing valuable insights into the underlying reaction mechanisms.

Synergy between Fe-Co oxide catalysts supported over HZSM-5 for direct conversion of methane to methanol

The direct conversion of methane to methanol over iron and cobalt oxide based composite catalysts supported over HZSM-5 was carried out in a fixed-bed micro reactor under changing process parameters and catalyst compositions. The prepared catalysts were well characterized by various techniques including N2 adsorption desorption, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), pyridine FTIR, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and temperature programmed reduction (H2-TPR). The characterization results revealed the presence of various reducible iron and cobalt oxide species depending on the Fe/Co molar ratio and total metal oxide loading. Moreover, the XPS and UV–vis spectroscopic results also confirmed the variation of Fe2+/Fe3+ and Co2+/Co3+ species depending on the Fe-Co molar ratio which had strong influence on the performance of the composite catalysts. It was found that the cobalt species favours the formaldehyde formation whereas the iron species promotes the formic acid formation in their respective pure supported oxide catalysts. However, the synergistic effect of iron and cobalt oxide in equimolar ratio in composite catalysts appeared as effective for achieving highest yield of methanol. The methanol selectivity was also influenced by the alteration of various studied process parameters. The higher reaction temperature favoured the overoxidation of methanol to CO2 whereas the methanol selectivity increased with increasing the methane to oxygen ratio. The lattice to adsorbed oxygen ratio also had strong influence on the activity of composite catalysts and methanol selectivity. The highest methanol yield of 1.87% was achieved at the methane conversion of 42.81 % with the 20Fe1Co1Z catalyst at 873 K reaction temperature with CH4/O2 ratio of 2:1 and WHSV of 1030 ml hr−1 gcat−1.

A quantitative investigation on pyrolysis behaviors of metal ion-exchanged coal macerals by interpretable machine learning algorithms

Generalizing the rules from complex processes such as catalytic pyrolysis to guide their process control is always a difficult but attractive task. The influences of ion-exchange of metal ions (Na+, K+, Ca2+, Mg2+, Co2+ and Ni2+) on the pyrolysis behavior of vitrinite and inertinite from Shendong coal were investigated by thermogravimetric analyzer-Fourier transform infrared spectrometer (TG-FTIR), fixed-bed reactor (FBR), gas chromatograph-mass spectrometer (GC-MS) and X-ray diffractometer (XRD). A set of machine learning models was successfully constructed based on random forest, support vector machine, and Gaussian process regression, to quantify the relationships between pyrolysis behaviors and the properties of metals and macerals. The leave-one-out-cross validation showed that there are considerable determination coefficients (R2 > 0.9) between predicted and experimental values for most responses (17 out of 29). By combining genetic programming-based symbolic regression with the black-box algorithm, 23 symbolic regression expressions with high confidence were successfully constructed. This work is a pioneering attempt of optimization in small-scale experiments. By utilizing the highly interpretable models, a demand-orientated (multi-)optimization coal pyrolysis can be achieved. The bi-objective optimization was conducted on the yield of tar and the content of light aromatics in tar, and the results show that Co is the optimal loading metal.

Enhancing biomass gasification: A comparative study of catalyst applications in updraft and modifiable-downdraft fixed bed reactors

This study aims to investigate the effects of different catalysts on biomass gasification. Therefore, red mud (RM) and Aluminum–Nickel alloy were used as catalysts with biomass mixture (BM) for the lab-scale gasification studies by using an updraft and a modifiable-downdraft fixed bed reactor. The maximum volumetric percentage of H2, ranging from 51% to 65%, was achieved at 900 °C in both gasifiers. Al–Ni catalyst significantly boosted H2 content, reaching 65% in the updraft gasifier at 900 °C with 0.05 L/min dry air. H2/CO ratio varied from 2 to 4 for BM, while catalyst use expanded the range to 1.6–7 with the Al–Ni catalyst demonstrating the most effective performance. In general, it was seen that RM increased the H2 component in the syngas between 1 and 7 vol% at 900 °C in updraft gasifier. In the modifiable-downdraft reactor, on the contrary, H2 concentration in the syngas decreased by 2–6% with the addition of RM.