Catalyst Loading Amount Research Articles

Supercritical CO2-promoted degradation of polystyrene to aromatic oils with NiO@C catalyst

Exploring new system for chemical recycling of plastic is an effective way to convert plastic waste into energy. Herein, the use of supercritical CO2 (ScCO2) to promote the catalytic degradation of polystyrene (PS) with high yield of aromatic oils was proposed. ScCO2 provided a homogeneous environment for the reaction, which not only facilitated the swelling of PS, but also inhibited the formation of coke, beneficial for the degradation of PS to aromatic oils. In addition, CO2 as an oxidant reacted with PS or intermediates to generate new products. NiO@C catalyst prepared by doping carbon material in NiO had a simple preparation process, an abundance of porous structure and strong acidic sites, thus improving the catalytic activity. Under the co-action of ScCO2 and NiO@C, the yield of aromatic oils produced from PS was up to 89.3 ± 0.6 wt% at 300 °C with a reaction time of 2 h and a catalyst loading amount of 10 wt%. Moreover, the NiO@C catalyst was used for three cycles without obvious change in the catalytic performance. The efficient catalytic degradation of PS to aromatic oils by ScCO2 promoted NiO@C catalysis provides a potential route for simultaneously recycling plastic and sequestering carbon.

Production of Biodiesel from Crude Pittosporum resiniferum Oil Using Heterogeneous Solid Base Catalyst

ABSTRACTPittosporum resiniferum oil was extracted from the seed and the oil together with methanol was use for the production of biodiesel through transesterification process using novel solid base catalyst (K2CO3 supported on MgO). 0.6:5 (K2CO3 loaded on MgO), a 5 h calcination time, 600°C calcination temperatures were the optimum conditions under which the catalyst was prepared. FTIR, SEM, CO2‐TPD, XRD, N2 adsorption‐desorption, Hammett indicators and other techniques were used to characterize the catalyst. The molar ratio of methanol‐to‐oil, the catalyst amount, time of the reaction as well as the temperature of the reaction were examined. The study found that 16:1 methanol‐to‐oil molar ratio, 5% catalyst loading amount, a reaction time of 2.0 h, and a reaction temperature of 60°C were sufficient for a maximum yield of 97.4%. With relative high activity, the catalyst can perhaps be used again possibly for five times. The characteristics of the biodiesel produced were consistent with international standards.

Nickel-Catalyzed Alkene Isomerization to Access Bench-Stable Enamines and Their [3 + 2] Annulation.

Enamines are difficult to prepare on the bench due to their instability, which results in side reactions, decompositions, poor yields, etc. Herein, we developed a simple and effective method for making bench-stable enamines using a very low amount of nickel catalyst loading. The deuterium exchange, competitive reaction, and radical clock experiment have all been found to favor the ionic mechanism of this alkene isomerization. Scale-up and [3 + 2] annulation reaction of enamines with activated cyclopropane to deliver cyclopentane derivatives have shown the value of this method in organic synthesis.

Production of alkyl levulinates as a versatile precursor by phosphomolybdate-impregnated g-C3N4 catalysts

Alkyl levulinates are a class of compounds that have diverse applications and show great promise as environmentally friendly fuel additives. These compounds are renewable, have a high energy density, and can easily be used with existing infrastructure. Therefore, they can play a significant role in contributing to the ongoing endeavors toward more sustainable and efficient energy solutions. In this study, alkyl levulinates (ALs) as fuel additives were synthesized using phosphomolybdate g-C3N4 (PMox/g-C3N4) as an efficient catalyst for the esterification reaction of levulinic acid (LA) with three diverse alcohols, namely ethanol, 1-butanol, and 1-hexanol. An experimental investigation assessed the impact of several key factors, such as temperature, the volumetric proportion of LA to alcohol, reaction time, catalyst loading, and catalyst amount, on the chemical process under study. For ethyl levulinate (EL) a 76 % yield was obtained at 130 °C, 8 h reaction time, LA: ethanol 1:12, and 20 mg catalyst. Also, a > 99 % yield was obtained for the butyl levulinate (BL) production at 130 °C, 8 h reaction time, LA: alcohol proportion of 1:12, and 10 mg catalyst. Hexyl levulinate (HL) was achieved with 71 % yield under the optimal condition of 230 °C, 8 h reaction time, LA: hexanol 1:20, and 10 mg catalyst.

Hematite-Gamma Alumina-based Solid Catalyst Development for Biodiesel Production from Palm Oil

This research investigated the performance of hematite-gamma alumina (Fe2O3/γ-Al2O3) catalyst in biodiesel production from palm oil. A full factorial experimental design was utilized to analyze the effect of hematite content, catalyst loading, and methanol-to-oil ratio on catalyst performance. From the experiment, biodiesel in the range of 73.6 to 87.6% FAME content was obtained. It was concluded that the catalyst composition, the methanol-to-oil ratio, and the catalyst loading have a significant effect on the FAME content of the biodiesel. Hematite has strong affinity for fatty acids, so a larger hematite surface area will result in a higher fatty acid absorption capacity. The addition of excess methanol can reduce the contact inhibition between the reactants and the active site of the catalyst, thereby increasing the conversion rate of the reaction. Moreover, a higher amount of catalyst loading can result in an increase in the FAME content when accompanied by an increase in the hematite content of the catalyst.

Investigation of Jatropha Oil Transesterification into Methyl Esters under Supercritical Methanol Environment using Advanced Heterogeneous Catalysts

AbstractThe rationale for this study lies in the investigation of the transesterification of crude Jatropha curcas oil into biodiesel using advanced heterogeneous catalysts under supercritical methanol conditions. The oxides of strontium, lanthanum, and zinc (SrO, La2O3, and ZnO) were synthesized with varying loadings (2 wt %, 6 wt %, and 10 wt %) on γ‐Al2O3 using the wet impregnation method followed by calcination at 900 °C. To gain a comprehensive understanding of the prepared catalysts, multiple analytical techniques were employed, including scanning electron microscopy (SEM) with energy‐dispersive X‐ray spectroscopy (EDS), Brunauer‐Emmett‐Teller (BET) surface area analysis, X‐ray diffraction (XRD), and Fourier transform infrared (FT‐IR) spectroscopy. The performance of the catalysts was assessed through the measurement of biodiesel yield, where the SrO/γ‐Al2O3, ZnO/γ‐Al2O3, and La2O3/γ‐Al2O3 systems produced yields of 97.54 %, 97.49 %, and 97.36 %, respectively, under identical reaction conditions of a 1 : 40 oil to methanol molar ratio, 10 wt % catalyst loading amount, 300 °C reaction temperature, 90 bar reaction pressure, and a reaction time of 3 min. Despite a minimal decrease of 0.05 %, zinc oxide catalysts remain highly attractive due to their favorable price position compared to strontium. Additionally, the catalyst can be reused up to 12 times with minimal loss in biodiesel yield (~2 %).

Investigating the Impact of Catalyst Penetration into Gas Diffusion Layer on the Performance of High-Temperature Polymer Electrolyte Membrane Fuel Cells

The catalyst fabrication method, cell assembly, and operating conditions in polymer electrolyte membrane fuel cells (PEMFC) impact the catalyst penetration into the gas diffusion layer (GDL), alter its porous structure, and, consequently, the overall cell performance. This study investigates the effect of the catalyst layer (CL) penetration thickness, catalyst loading amount, and cell compression during assembly on species and current distributions, and overall cell performance. GDLs with large penetration thickness show a substantial resistance to reactant and proton transport, particularly at high current densities resulting in a drop in the cell performance. For zero, 50%, and 100% penetrations, the average current densities at an operating voltage of 0.4 V are 0.8329, 0.7920, and 0.71112 A cm−2, respectively. This indicates a performance loss of 5% and 15% for 50% and 100% penetrations in comparison to zero penetration. Higher catalyst loading results in greater penetration, negating the benefit of enhanced kinetics. Performance typically decreases by 3%–5% for 50% penetration and 12%–15% for 100% penetration when penetration levels increase for a certain Pt loading. An attempt is made to investigate the interplay between the effect of reactant and proton transport limitations on their distributions and cell performance. The combined effect of catalyst penetration and cell compression during the assembly has a crucial impact on cell performance with the starvation of reactants at high-density regions. The study highlights the necessity of optimizing the penetration thickness, catalyst loading, and cell assembly to achieve maximum cell performance.

Efficient methylene blue dye removal using hybrid ZnO/Co/Cs photocatalyst beads

This study highlighted the developments of the hybrid photocatalytic system for wastewater treatment in the textile industry. Chitosan (Cs) and cobalt (Co) were introduced into the conventional catalyst zinc oxide (ZnO) to form the hybrid photocatalyst beads. Four different weight ratios of ZnO/Cs (1:1) and ZnO/Co/Cs (1:1:1, 1:2:1 and 2:1:1) beads were synthesized by the sol-gel method. The photocatalytic degradation properties of the hybrid ZnO/Co/Cs were investigated under visible light irradiation for methylene blue (MB) photodegradation. The study focused on the effect of ZnO/Co/Cs composition ratio, irradiation time and the amount of catalyst loading in the photoreactor for five hours of exposure time. The result was that the 1:1:1 ZnO/Co/Cs photocatalyst beads had the highest degradation rate compared to the other systems. Adding Co to the ZnO/Cs photocatalyst improved the photocatalytic activity by increasing the decolourization percentage of methylene blue

Performance and Durability of Membrane-Electrode Assemblies Using Non-Precious Metal Catalyst and a Hydrocarbon-Based Electrolyte for Anion Exchange Membrane Water Electrolysis

Anion exchange membrane water electrolysis (AEMWE) is operated in an alkaline environment and has a similar membrane-electrode assembly (MEA) structure to that of proton exchange membrane water electrolysis (PEMWE). The use of non-noble metals as the electrocatalysts and operation at high current densities are inherently possible, so they are expected to be low-cost, high-performance candidates for next-generation water electrolysis systems. Improving the anion conductivity of the AEM and the activity of the non-precious metal catalysts is essential for the practical application of AEMWEs.1 The non-noble electrocatalysts used in the MEA in this study were Ni0.8Co0.2O2 and Ni0.8Fe0.2O,3 which have a fused-aggregate network structure, and the electrolyte was a hydrocarbon-based AEM (QPAF-4)4, all of which were developed at the University of Yamanashi.The catalyst ink for the anodes was prepared by mixing the Ni0.8Co0.2O catalyst (University of Yamanashi) with solvent (water/methanol) and QPAF-4 (IEC = 2.0 meq g-1, University of Yamanashi) binder solution. The anode ink was coated by using pulse-swirl-spray (PSS, Nordson) on the QPAF-4 membranes (IEC = 1.5 meq g-1) to make the catalyst-coated membranes (CCMs) with the anode. Catalyst inks for the cathodes was prepared by mixing Ni0.8Fe0.2O catalyst (University of Yamanashi) or Pt/CB catalyst (TEC10E50E, Tanaka Kikinzoku) with solvent (water/methanol) and QPAF-4 (IEC = 2.0 meq g-1) binder solution. The cathode ink was coated by using PSS on the gas diffusion layer (GDL, TGP-H-120, Toray) to make the gas diffusion electrodes (GDEs) for the cathodes. Ni mesh (Bekaert.co.jp) was used for the anode GDLs. The single cell (Figure 1, cell structure developed by Yokohama National University) performances were measured while supplying 1 M KOH at 80 °C to both electrodes.Figure 2 (a) shows the I-V performance of cells using Ni0.8Co0.2O for the anode and Ni0.8Fe0.2O or Pt/CB for the cathode. The electrolysis voltage observed for the cell with non-noble metal catalysts on both electrodes was higher than that for the cell with Pt/C on the cathode but was below 2 V at a current density of 1.2 A cm-2. The value of the onset electrolysis voltage was nearly the same as that of the corresponding rotating disk electrode,3 suggesting that the intrinsic performance of the cathode catalyst is being realized in the MEA. Increasing the amount of the cathodic catalyst loading scarcely affected the polarization. It is supposed that the fused-aggregate network structure of the Ni0.8Fe0.2O catalyst contributes to the favorable mass transfer. Figure 2 (b) shows the time dependence of the cell voltage of these cells. The increased loading amount improved the durability of the cathode. It is considered that the increase in the thickness of the cathode catalyst layer alleviated the damage of the GDL fibers to the membrane.These results indicate the possibility of adopting non-precious metal catalysts for both electrodes in AEMWE and thereby significantly reducing the catalyst cost. Acknowledgement This work was partially supported by NEDO of Japan through the AWE-1 project. References 1) A. Lim et al., J. Ind. Eng. Chem., 76, 410 (2019).2) G. Shi et al., ACS Catal., 12, 14209 (2022).3) G. Shi et al., ACS Omega, 8, 13068 (2023).4) H. Ono et al., J. Mater. Chem. A, 5, 24804 (2017). Figure 1

Synthesis, Adsorption and Catalytic Properties of Eggshell-Coconut Pith for Transesterification of Waste Cooking Oil

This study aims to develop a sustainable heterogeneous biocatalyst prepared from calcined eggshell waste impregnated with waste coconut piths for producing biodiesel from used cooking oil. Waste eggshells were subjected to thermogravimetric analysis for calcinations at suitable temperature under inert atmosphere. It was subjected to impregnation of coconut pith by physical and chemical adsorption. The prepared eggshell-coconut pith catalyst was optimized at different parameters like temperature, mass ratio of coconut pith, eggshell and variant concentration of the solvent used for socking of coconut pith and eggshell. The adsorption of coconut pith on the eggshell surface were characterized by BET analysis and SEM analysis, the size of atom of eggshell was increased after impregnation of coconut pith by 100 μm. The adsorption of coconut pith on eggshell was validated by Langmuir and Freundlich adsorption models and order of impregnation reaction was verified by pseudo-first and pseudo-second order models. The effect of process parameters like amount of catalyst loading, oil: alcohol ratio, time, speed of iteration, pH of the solvent and temperature, which enhanced the yield of biodiesel to ~ 87%.

Catalytic steam gasification of bituminous coal for syngas production with catalyst derived from calcium-rich construction demolition waste

A disposable Ca-containing catalyst was generated from a sort of calcium-rich construction demolition waste and utilized in the steam gasification of a bituminous coal in a fixed bed reactor. The effects of catalyst loading amount, gasifying temperature and catalyst loading method on steam gasification with respect to the production of syngas with high H2/CO mole ratio and CH4 content were investigated. The H2 and CO molar yields as well as carbon conversion increased noticeably with the increase of catalyst loading amount despite there was a saturation quantity. After loading 6.0 wt% catalyst into coal by kneading method, the carbon conversion and total gas molar yield increased from 52.56% and 136.06 mmol/g-C to 62.77% and 160.23 mmol/g-C, respectively. At low temperature, kneading method displayed superiority over mechanical mixing method in steam gasification performance of bituminous coal while they had approximately the same catalytic effect on coal steam gasification at high temperature. Characterization of SEM images and Raman spectroscopy of coal chars derived from catalytic pyrolysis confirmed that addition of catalyst changed the micro-crystal structure and formed more defects and amorphous structures. Overall, the catalyst showed satisfactory catalytic effect in steam gasification of bituminous coal and could be used as a suitable alternative of CaO for syngas production.

Low-temperature catalytic oxidation of PCDD/Fs over MnCeCoOx/PPS catalytic filter.

Catalytic destruction of nitrogen oxides (NOx) combined with dust removal technique has attracted much attention, yet the application in the solid waste incineration air pollution control process is still lacking due to the complex flue gas atmosphere. In this work, the Mn-Ce-Co-Ox catalyst-coated polyphenylene sulfide (PPS) filter fiber with efficient dust removal and low-temperature polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) destruction has been prepared with a redox-precipitation method. The catalyst was uniformly grown around the PPS fiber with appropriate catalyst loading. The effects of several key operating parameters (e.g., reaction temperature, catalyst loading amount, and filtration velocity) on the catalytic efficiency were comprehensively investigated. The results show that the Mn-Ce-Co-Ox/PPS has a decomposition yield of 78.0% in PCDD/Fs and 96% in nitric oxide (NO) conversion at 200 °C. The poisoned catalytic filter exhibits a removal efficiency of 88.6% for PCDD/Fs. In addition, the catalytic filter can completely reject particles smaller than 1.0 μm with a low filtration resistance. Therefore, this efficient and energy-conserving catalytic filter shows promising applications in flue gas pollution treatments.

Experimental Studies of Gasification of Glycerol for The Production of Hydrogen

In this study, pure glycerol and crude glycerol conversion to hydrogen gas were investigated using a fixed-bed reactor. The gasifying agent utilised for this research is steam. The efficiency of the reaction was based on the results data of the H2 yield obtained. The reaction wasconducted using two different packing materials, which were silicon carbide and quartz. The effect of packing material was investigated. Next, steam-to-glycerol ratios were varied in the range of 0:0, 10:90, 25:75 and 50:50 to study the influence of the ratios on the producthydrogen gas. The effect of the catalyst and the amount of catalyst loading was investigated using a Ni/Al2O3 catalyst. The effect of temperature on the yield of product was studied in the range of 650 - 800◦C. Product gasses H2, CO2, CO and CH4 were analysed using TCD and NDIR analysis. The highest purity of H2 was 65 mol% at the optimised condition of 25:75 steam to glycerol ratio and 800◦C.Keywords: glycerol, crude, hydrogen, gasifying, fixed bed reactor pyrolysis

High quality syngas production from catalytic steam gasification of biomass with calcium-rich construction waste

High quality syngas was produced by steam gasification of biomass waste with catalyst derived from disposable calcium-rich construction waste after calcination (C-CCW) at high temperature. The effects of biomass gasification parameters including operating temperature, catalyst loading amount and biomass varieties on characteristics of biomass steam gasification were studied. Experiment results indicate that the total gas yield of produced gas derived from steam gasification of corn stalk increased markedly with elevated reaction temperature and catalyst loading amount. Addition of C-CCW on biomass significantly promoted the decomposition of tar in syngas during steam gasification resulting in higher gas yield and better gas quality. The considerable H2 yield (29.70 mmol/g-biomass), CO yield (4.14 mmol/g-biomass), CH4 yield (3.40 mmol/g-biomass), and H2/CO mole ratio (7.17) were achieved after steam gasification of corn stalk with 10.0 wt% C-CCW at 750 °C. There were significant differences in steam gasification performance of different biomass samples owed to the properties of biomass feedstock. Distinct saturation capacities of C-CCW loading amount were observed for enhancing gasification and eliminating tar during steam gasification of diverse biomass feedstocks. C-CCW appeared to have comparable catalytic effect to that of pure CaO and therefore could be an alternative of calcium-containing catalyst.

In situ detection with interdigitated array electrodes towards the platinum-catalyzed oxygen reduction reaction: Size effect and the reaction pathway

Platinum has long been recognized as a vital catalyst in energy conversion and utilization, particularly in oxygen reduction reaction (ORR), due to its exceptional catalytic activity. However, its exorbitant cost and scarcity have motivated researchers to explore the size-activity correlation of Pt catalysts in ORR, aiming to reduce Pt loading density while preserving high catalytic performance. In this work, we concentrate on the interdigitated-array(IDA)-electrodes-based precise detection of the influence of Pt cluster size on catalytic ability, focusing on (1) Direct synthesis of Pt catalyst onto electrodes surface, rather than offline preparation and pasting, to avoid interference from other chemicals and changes to the surface status of catalyst particles; (2) Use of IDA electrodes with largely improved sensitivity for in-situ detection of reaction intermediates (H2O2) and provide insight into the reaction pathway and electron transfer process. It indicates that the specific activity and mass activity are larger for the smaller-sized Pt cluster. Specifically, the proportion of different electron transfer pathways was analyzed with IDA results, and with the same amount of Pt catalyst loading, the smaller-sized Pt cluster produces a higher percent of H2O2; the smaller-sized Pt catalyzed ORR undergoes less proportion of 4-electron pathway than the larger-sized Pt catalyst (about 43% total catalytic current is contributed by the 4-electron pathway for the #6 Pt catalyst, and this number raises to 98% for the #1 Pt catalyst).

Synthesis of Biodiesel from Used Frying Oil Using Modified Banana Peel Waste as A Heterogeneous Catalyst

In this study, biodiesel was synthesised from a transesterification reaction of used frying oil (UFO) catalysed by modified banana peel waste (Modified-BPW). The catalyst properties were characterised using Fourier Transform Infrared Spectrometer (FTIR) and Scanning Electron Microscopy (SEM) analyses. The reaction parameters were varied to evaluate the optimal reaction parameters that could influence the biodiesel yield, such as methanol to oil molar ratio, catalyst loading amount and water content presence in the UFO at a fixed reaction time of 2 hours and a reaction temperature of 65°C. The catalytic activity resulted in the reaction condition of 12:1 of methanol to oil molar ratio, 1 wt.% of catalyst dosage and 0.5 wt.% water content in UFO, obtaining the highest biodiesel yield of 88.7%. The results indicated that the Modified-BPW could be a promising catalyst for biodiesel synthesis from UFO.
 Keywords: Biodisel, transesterification, used frying oil, banana peel waste and modified heterogeneous catalyst

A Swiss-Roll-Type Methanol Mini-Steam Reformer for Hydrogen Generation with High Efficiency and Long-Term Durability.

This paper proposes a Swiss-roll-type mini-reformer employing a copper-zinc catalyst for high-efficient SRM process. Although the commercially available copper-zinc catalysts commonly used in cylindrical-type reformers provide decent conversion rates in the short term, their long-term durability still requires improvement, mainly due to temperature variations in the reformer, catalyst loading, and thermal sintering issues. This Swiss-roll-shaped mini-reformer is designed to improve thermal energy preservation/temperature uniformity by using dual spiral channels to improve the long-term durability while maintaining methanol-reforming efficiency. It was fabricated on a copper plate that was 80 mm wide, 80 mm long, and 4 mm high with spiral channels that were 2 mm deep, 4 mm wide, and 350 mm long. To optimize the design and reformer operation, the catalyst porosity, gas hourly speed velocity (GHSV), operation temperature, and fuel feeding rate are investigated. Swiss-roll-type reformers may require higher driving pressures but can provide better thermal energy preservation and temperature uniformity, posing a higher conversion rate for the same amount of catalyst when compared with other geometries. By carefully adjusting the catalyst bed porosity, locations, and catalyst loading amount as well as other conditions, an optimized gas hourly space velocity (GHSV) can be obtained (14,580 mL/g·h) and lead to not only a high conversion rate (96%) and low carbon monoxide generation rate (0.98%) but also a better long-term durability (decay from 96% to 88.12% after 60 h operation time) for SRM processes. The decay rate, 0.13%/h, after 60 h of operation, is five-folds lower than that (0.67%/h, 0.134%/h) of a commercial cylindrical-type fixed-bed reactor with a commercial catalyst.

Stretchable Enzymatic Biofuel Cells Based on Microfluidic Structured Elastomeric Polydimethylsiloxane with Wrinkled Gold Electrodes

AbstractVarious sensors and electronic devices are recently developed to monitor human health in mechanically flexible or even stretchable forms for intimate contact with non‐flat curvilinear surfaces of the human body. For successful operation of these devices, finding a proper way to electrically power them is very important. In this work, glucose/oxygen fueled enzymatic biofuel cells (EBFCs) based on microfluidic structured elastomeric polydimethylsiloxane substrate with wrinkled gold (Au) electrodes are suggested for power supply. For doing that, firstly, bottom surface of microfluidic channel is covered with buckled Au electrodes for stretchability. By microfluidic design showing capillary imbibition through fluidic channels, loading of catalyts is promoted. Interestingly, buckled Au electrodes induce much better anodic and cathodic reaction rates than those of non‐buckled Au electrodes by 25% and 33%, respectively. This is because surface area and the amount of catalyst loading in electrodes increase by Au wrinkling. In evaluations of EBFCs using the buckled Au electrodes, maximum power density reaches 7.1 ± 0.64 µW cm−2, while they show decent performance of 5.4 ± 0.49 µW cm−2 even under external stretching. Taken together, it is corroborated that such proposed stretchable EBFCs are alternative for providing electrical power in wearable or implantable devices.

Synthesis of Trimetallic Nanoparticle (NiCoPd)-Supported Carbon Nanofibers as a Catalyst for NaBH4 Hydrolysis.

The generation of H2 via the catalytic hydrolysis of sodium borohydride (SBH) has promise as a practical and secure approach to produce H2, a secure and environmentally friendly energy source for the foreseeable future. In this study, distinctive trimetallic NiCoPd nanoparticle-supported carbon nanofibers (NiCoPd tri-NPs@CNFs) is synthesized via sol-gel and electrospinning approaches. The fabricated trimetallic catalysts show an excellent catalytic performance for the generation of H2 from the hydrolysis of SBH. Standard physicochemical techniques were used to characterize the as-prepared NiCoPd tri-NPs@CNFs. The results show that NiCoPd tri-NPs@CNFs is formed, with an average particle size of about 21 nm. When compared to NiCo bimetallic NP @CNFS, all NiCoPd tri-NPs@CNFs formulations demonstrated greater catalytic activates for the hydrolysis of SBH. The improved catalytic activity may be due in the majority to the synergistic interaction between the three metals in the trimetallic architecture. Furthermore, the activation energy for the catalytic hydrolysis of SBH by the NiCoPd tri-NPs@CNFs was determined to be 16.30 kJ mol-1. The kinetics studies show that the reaction is of a first order with respect to the catalyst loading amount and a half order with respect to the SBH concentration [SBH].

Alkali and alkaline earth metals catalytic steam gasification of ashless lignin: Influence of the catalyst type and loading amount

This work studies the effects of alkali and alkaline earth metallic species (AAEMs) (Na2CO3, K2CO3, and CaCO3), Na+ impregnation amount (2, 5, and 7 mmol) and sodium salts (NaHCO3, Na2SO4, and NaAlO2) on the gasification characteristics and product distribution of G-type lignin in a fixed-bed system for continuous gasification. The results showed that six catalysts all could improve lignin gasification performance by increasing total gas yields, syngas yields, H2/CO ratios, and carbon conversion rates. Na2CO3 had the strongest catalytic ability, followed by NaHCO3 and K2CO3, while CaCO3, Na2SO4 and NaAlO2 had poor catalytic abilities. Gaseous AAEMs, especially NaOH and KOH, could enhance tar cracking, volatiles reforming, coke gasification, the water-gas shift reaction, and methane steam reforming. The high melting points of CaO and NaAlO2 greatly reduced the catalytic capacities of CaCO3 and NaAlO2. AAEMs could combine with the carbon matrices to form carboxylate structures or phenol/aldehyde structures which might volatilize to catalyze homogeneous reactions. Moderately increasing Na+ impregnation amount to 5 mmol was beneficial to lignin gasification, but excessive impregnation reduced the gasification parameters. In addition, all six catalysts had effects on the tar composition, especially K2CO3 and NaAlO2, which could effectively catalyze tar cracking and reduce heavy compounds.