Fresh Catalyst Research Articles

An effective descriptor for identifying the electrocatalytic activity and selectivity of bilayer carbon-based heterojunction catalysts

The usage of composite carbon-based materials supported by graphene has emerged as a powerful selection for designing electrocatalytic electrodes due to their agile electronic transmission and diversiform redox active sites. Here, we constructed fresh electroactive organic catalysts for hydrogen carrier synthesis by stacking a series of organic molecules on transition metal azide doped graphene substrates, in anticipation of these bilayer heterostructures to breathe new life into electrocatalysis. As expected, several promising cathodic catalysts were speculated through first principles calculations, such as Co-PMDT for H2 generation and Co-PQ for ammonia (NH3) synthesis. However, facing such an intricate interface engineering and electronic structure regulation undoubtedly poses a challenge to the time-consuming computational screening work. To tackle this, an effective descriptor was proposed as a predictive tool for identifying the activity and selectivity toward diverse chemical reactions, which allows us to systematically fine-tune the catalysts' properties in order to enhance their electrocatalytic performance. Our work may offer feasible approaches for the rational design of advanced electrocatalysts.

Study on the Regeneration of Waste FCC Catalyst by Boron Modification.

Regeneration has been considered as an ideal way for the post-treatment of waste FCC catalyst (ECat). In this work, the degeneration mechanism of ECat was firstly researched and attributed to the increasing of strong acid sites accessibility of ECat in contrast with fresh FCC catalyst by adsorption FTIR. Based on the proposed degeneration mechanism, ECat was successfully regenerated through suitable weakening for strong acid sites by boron modification. Characterization and evaluation results suggested that, the strong acid sites of regenerated ECat (R-ECat) were apparently decreased by boron modification which had significantly improve the heavy oil catalytic cracking performance of R-ECat. Because of the excellent performance, R-ECat in this work could successfully substitute for partial fresh FCC catalyst in FCC unit, which would provide a practicable way for the reutilization of ECat.

The Effect P Additive on the CeZrAl Support Properties and the Activity of the Pd Catalysts in Propane Oxidation.

The properties of a catalyst support are closely related to the catalyst activity, yet the focus is often placed on the active species, with little attention given to the support properties. In this work, we specifically investigated the changes in support properties after the addition of P, as well as their impact on catalyst activity when used for catalyst preparation. We prepared the CeO2-ZrO2-P2O5-Al2O3 (CeZrPAl) composite oxides using the sol-gel, impregnation, and mechanical mixing methods, and characterized the support properties using techniques such as XRD, XPS, SEM-EDS, N2 adsorption-desorption, and Raman spectra. The results showed that the support prepared using the sol-gel method can exhibit a more stable phase structure, larger surface area, higher adsorption capacity for oxygen species, and greater oxygen storage capacity. The addition of an appropriate amount of P is necessary. On the one hand, the crystallization and growth of CePO4 can lead to a decrease in the Ce content in the cubic phase ceria-zirconia solid solution, resulting in a phase separation of the ceria-zirconia solid solution. On the other hand, CePO4 can lock some of the Ce3+/Ce4+ redox pairs, leading to a reduction in the adsorption of oxygen species and a decrease in the oxygen storage capacity of the CeZrPAl composite oxides. The research results indicated that the optimal P addition is 6 wt.% in the support. Therefore, we prepared a Pd/CeZrPAl catalyst using CeZrAl with 6 wt.% P2O5 as the support and conducted the catalytic oxidation of C3H8. Compared with the support without P added, the catalyst activity of the support loaded with P was significantly improved. The fresh and aged (1000 °C/5 h) catalysts decreased by 20 °C and 5 °C in T50 (C3H8 conversion temperature of 50%), and by 81 °C and 15 °C in T90 (C3H8 conversion temperature of 90%), respectively.

Effective photo-catalytic degradation of Malachite Green with water stable Cu based aliphatic di-carboxylate MOFs

Four different mesoporous Cu-MOFs named as Cu(Pima), Cu(Suba), Cu(Azla) and Cu(Seba) were prepared from aliphatic di-carboxylate linkers with the dimeric Cu paddle wheels as Secondary Building Units (SBUs). These as-synthesized aliphatic Cu-MOFs were applied as fresh heterogeneous catalysts for the catalytic wet peroxide oxidation of simulated Malachite Green waste-water and characterized using PXRD, FT-IR, Fe-SEM and BET. The results exhibited a better catalytic degradation efficiency of Cu(Seba) and Cu(Azla) (>90% in 200 mins) as compared to Cu(Pima) and Cu(Suba). It was established that degradation efficiency of Cu(seba) was approximately 9.8 times better than the rest of the synthesized Cu(MOFs). It was recognized that increasing the organic linker length can evidently boost the dye degradation process. Under optimum conditions, the degradation efficiency of 98% and 97% for Cu(Seba) and Cu(Azla) were achieved respectively. A optimal condition of 1.0 mL H2O2, 50 °C temperature and 3.5 pH was obtained. A recyclability experiment of four runs was performed for Cu(Seba) and Cu(Azla) which exhibited they maintained an effective degradation efficiency of ∼80% simulated MG solution. These analytical results of the degradation efficiency for Cu(Seba) and Cu(Azla) led us on a conclusion that, as synthesized Cu-MOFs outperformed several other reported MOFs, nanoparticles, adsorbents etc., as heterogeneous catalysts in the field of dye degradation for wastewater treatment.

Preparation and Catalytic Performance of the Copper-Manganese-Silicon Catalysts for Dehydrogenation Reaction of 2-butanol

Cu-Mn-Si catalysts with copper-manganese oxides as the main constituents and silica dioxide as the supports were prepared by co-precipitation method. The performance of the catalysts for the dehydrogenation reaction of the 2-butanol to methyl ethyl ketone was tested. The effects of Cu and Mn ratios on the catalytic performance were investigated. The catalysts were characterized by XRD, SEM, H2-TPR, TG, BET and XPS, to reveal the catalytic mechanism. The results showed that after adding the manganese, the copper-manganese complexes were formed in the catalysts, which effectively improved the activity of the catalysts. XRD results showed that a new phase of Cu-Mn complex was formed in the fresh catalysts, and reduced copper species appeared in the spent catalysts; TPR results showed that the reduction temperature of the catalysts could be reduced by adding appropriate amount of manganese; XPS results showed that the proportion of Cu++Cu0 can be increased in the fresh catalyst and that of Cu2+ in the spent catalyst can be decreased after the addition of manganese. When the mole ratio of Cu, Mn and Si in the catalysts was 0.8:0.2:1, the conversion of 2-butanol could reach 94.9%, and the selectivity of methyl ethyl ketone was 98%.

Dendritic ZSM-5 zeolites as highly active catalysts for the valorization of monoterpene epoxides.

Dendritic ZSM-5 zeolites were investigated in the isomerization of monoterpene epoxides, including limonene-1,2-epoxide (LE), α-pinene epoxide, and β-pinene epoxide, which yields high-value compounds used in fragrances, cosmetics, and pharmaceuticals. The fresh catalysts were thoroughly characterized using XRD, Ar physisorption, pyridine-FTIR, TEM, FTIR/DTBPyr, and 27Al MAS NMR. In comparison with conventional and hierarchical ZSM-5 materials, the dendritic zeolite with a crystallization time of 4 days (d-ZSM-5/4d) was the most active material, with a turnover frequency value of 4.4 min-1 for LE isomerization. Likewise, remarkable yields of dihydrocarvone (DHC, 63%, 70 °C, 2 h), campholenic aldehyde (72.4%, 70 °C, 5 min), and myrtanal (47.7%, 50 °C, 5 min) were obtained with this material that exhibited the largest mesopore/external surface area (360 m2 g-1), showing also the narrowest mesopore size distribution. A direct relationship was observed between the TOF values and the concentration of external Brønsted acid sites, showing the presence of strong steric/diffusional limitations that are greatly overcome with the dendritic zeolites. The lower reactivity of trans-LE compared to cis-LE was attributed to the larger steric hindrance of the oxygen atom. Exploration of the solvent influence revealed that the reaction rate of LE was favored by non-polar solvents, while highly selective DHC formation occurred in the solvents of medium polarity. The d-ZSM-5/4d sample was shown to be robust because catalytic activity could be completely recovered by air calcination.

EFFECT OF MICROSTRUCTURES ON MASS TRANSFER INSIDE A HIERARCHICALLY STRUCTURED POROUS CATALYST

In this paper, the pore network model to investigate the reaction-diffusion process in the hierarchically structured porous catalyst particle is extended to consider the phenomenon of deactivation by coking. In this framework, the interaction of internal particle pore structure and mass transfer under the condition of coke deposition is examined. Then, the effect of structural features, namely macroporosity and pore size ratio, the deactivation properties, the maximum loading of coke, as well as the transport properties, the pore Damköhler number on the net reaction rate, and deactivation of the particle have been investigated. Three deactivation mechanisms are accounted for, namely, the site coverage, the pore narrowing, and the pore blockage. It is found that the deactivation of the catalyst particle can be divided into two conditions: the kinetic deactivation and the structural deactivation. It is shown that depending on the Damköhler number, increasing the macroporosity does not necessarily improve the reactivity and deactivation resistance of the catalyst. The key finding of this work is to demonstrate and quantify how changing the typical fresh catalyst microstructure into a hierarchical one influences the reactivity and deactivation.

Synthesis of ethyl furfuryl ether via etherification of furfuryl alcohol with ethanol over montmorillonite K10.

Ethyl furfuryl ether (EFE), which is synthesized via etherification of furfuryl alcohol (FFalc) with ethanol over Brønsted acid catalysts, is used as an additive in gasoline to reduce its consumption and CO2 emission. In this work, we demonstrate that the performance of this synthesis route can be improved by using commercially available, low-cost, and environmentally friendly montmorillonite K10, which produces EFE in a relatively high yield of 45.3% and a FFalc conversion of 94.2% at a low reaction temperature of 393 K within 1 h. Other commercially available clay minerals showing Brønsted acidity, namely, kaolinite and halloysite, were also used in the etherification reaction under identical conditions. The catalytic performance followed the order of montmorillonite K10 > halloysite > kaolinite, which is consistent with that of the Brønsted acidities determined via acid-base titration. The spent montmorillonite K10 showed a catalytic performance comparable to that of the fresh catalyst after calcination.

Efficient catalyst regeneration through solvent-based wax extraction for Co/Al2O3 Fischer-Tropsch catalysts

The regeneration of Fischer-Tropsch (FT) catalysts plays a crucial role in sustaining their catalytic activity and longevity in sustainable production processes. This research investigates the effectiveness of various solvents, including n-hexane, n-heptane, toluene, xylene, and the liquid fraction of FT products (LF-FT), for catalyst regeneration and extracting wax from the 15 wt%Co/Al2O3 catalyst. Toluene, with a unique combination of key parameters such as polarity, solubility, boiling point, aromatic structure, and chemical interactions, exhibited the highest wax removal efficiency of 90.6%. However, due to its 41 °C lower boiling point compared to toluene and very similar wax removal efficiency, n-hexane appears as a more energy-efficient and cost-effective option for this process. The regenerated catalysts showed comparable characteristics, including the textural properties (surface area, pore size, and pore volume), crystallinity, and reducibility, to fresh catalysts. The slightly lower reduction temperature in the regenerated catalyst indicates a higher possibility for the formation of cobalt active sites during the catalyst reduction process with hydrogen, leading to an increased potential for higher catalytic activity. The LF-FT, comprising paraffins, iso-paraffins, olefins, napthenes, and aromatics, provided a unique combination of aliphatic and aromatic moieties, enhancing the solubility of both polar and nonpolar components in FT wax and improving the wax removal efficiency to 91.5%. The higher boiling point and operating temperature of the LF-FT also contributed to its better performance. Efficient separation of hydrocarbons from solvents allowed for solvent reusability in subsequent FT wax removal cycles, making it advantageous for large-scale applications.

Unexpected offsetting effect of Na and HCl deactivation over CeO2-MoO3 catalyst for NO reduction

This work mainly illustrated the synergistic effects of Na and HCl on the SCR performance of CeMo catalysts. Given that the fresh CeMo catalyst was treated with HCl or doped by Na, the weakened acidity and oxidizability would interfere with the adsorption and activation of NH3, thus resulting in a downward trend of the catalyst deNOx performance. Notably, for the HCl treated Na-poisoned catalyst, the treatment with HCl introduced additional acid sites onto the Na-poisoned catalyst surface and increased the availability of Ce4+ and chemisorbed oxygen. These behaviors exerted a certain promotional effect on the adsorption and activation of NH3. Apparently, the catalyst's deNOx performance slightly rebounded, suggesting the offsetting effects of HCl. Such knowledge would be vital to the stable operation in real coal-fired flue gas.

Oxovanadium(IV) unsymmetrical salophen complex supported on modified silica-coated CoFe2O4 nanoparticles: A magnetically recoverable nanocatalyst for efficient and selective oxidation of sulfides and thiols

In this study, an oxovanadium(IV) unsymmetrical salophen complex, VO(salophen-OH) where salophen-OH = 4-[(E)-{(2-[(E)-2-hydroxybenzylidene)amino]phenyl}imino)methyl]benzene-1,3-diol, was synthesized and immobilized on the surface of chloro-functionalized silica-coated CoFe2O4 (CoFe2O4@SiO2@CPTMS) magnetic nanoparticles. FT-IR and EDX spectra, TEM and SEM images, XRD pattern, TGA, ICP, and VSM measurements were applied to characterize the resulting CoFe2O4@SiO2@CPTMS@VO(salophen-OH) nanoparticles. The developed CoFe2O4@SiO2@CPTMS@VO(salophen-OH) magnetic nanoparticle was used as a remarkably efficient nanocatalyst, which facilitates the chemo-selective oxidation of sulfides to sulfoxides using 30 % H2O2 and also enables the oxidative coupling of thiols to disulfides using urea/H2O2 (UHP) in ethanol at room temperature. This catalytic system presented disulfides and sulfoxides as optimal products that showed good to excellent yields, and there was no over-oxidation of disulfides and sulfoxides to undesirable by-products. An external magnet can be used to recover this nanocatalyst magnetically, and it can be recycled up to five times in both oxidation reactions without losing its catalytic action. Moreover, the recycled catalyst shows no major differences in its XRD pattern and FT-IR spectrum compared to the fresh catalyst.

Generating silicon-rich AFX zeolite using rigid diquaternary alkylammonium structure directing agent towards stable selective catalytic reduction of NOx by NH3

New synthetic protocols to manipulate Si/Al ratios of small pore zeolites hold promise to find better selective NOx reduction catalyst using NH3 as reducing agent (NH3-SCR). AFX zeolite as NH3-SCR catalyst is currently impeded by the insufficient hydrothermal stability owing to the low Si/Al ratio. In this contribution, we report the synthesis of AFX zeolite using N,N-(1,4-phenylenebis(methylene))bis(N,N,N-triethylammonium) as organic structure directing agent (OSDA) to increase the framework Si/Al ratio to 7.8, giving rise to a marked enhancement of hydrothermal stability to withstand hydrothermal aging at 850 °C for up to 10 h. The increase in Si/Al ratio for AFX zeolite minimizes catalytic cycle driven by Brønsted acid site and broadens high temperature operation window (150–515 °C) for Cu-exchanged catalyst. Moreover, the hydrothermally aged Cu-AFX catalyst exhibits comparable catalytic activity to that of the fresh catalyst owing to Cu predominant distribution close to the 6-MR.

Decolourization and degradation of azo-dyes by the NaClO/NiOOH catalytic oxidation system

ABSTRACT Azo dyes are highly toxic and difficult to degrade. Decolourization of acid red 18 (AR18) and reactive yellow 4 (RY4) dye wastewater by the NaClO/NiO x (OH) y catalytic system was studied. The influence of reaction conditions was investigated. Their degradation mechanism was discussed by free radical scavenging experiment, and the degradation pathways were proposed. The continuous flow experiment was conducted. The results showed that the catalytic oxidation has a good decolourization effect on AR18, but it is not ideal for RY4. The continuous flow experiment of 3000 min showed that the decolourization effect was stable. The concentration of Ni2+ in the effluent from the reactor was always up to the standard, and the catalyst was not deactivated. The decolourization mechanism of the two dyes is different: AR18 is mainly decolourized by atomic oxygen/singlet oxygen, while RY4 is mainly decolourized by NaClO. The catalysts were characterized by XPS and XRD. The surface contains the largest proportion of chemisorbed oxygen. With the extension of the catalyst service time, chemisorbed oxygen decreased slightly and was converted into atomic oxygen/singlet oxygen, which was consumed in the decolourization process. Compared with the used catalysts, the β-NiOOH crystallinity of the fresh catalyst is better. The quantitative structure–property relationship analysis based on the decolourization data shows that there is a good linear correlation between the decolourization rate of azo dyes and their molecular structure descriptors. The inorganic–organic properties balance (IOB) value was determined as the main molecular descriptor that affected the decolourization of dyes.

H2[Pt(C2O4)2] as a Tailor‐made Halide‐free Precursor for the Preparation of Diesel Oxidation Catalysts: Nanoparticles Formation, Thermal Stability and Catalytic Performance

AbstractThe aim of this study was to investigate a tailor‐made metal precursor and its chemical properties to tune the properties of supported metal nanoparticles (NPs) and their catalytic performance when used as Diesel Oxidation Catalyst (DOC). The formation of extremely small Pt NPs from a new halide‐free Pt complex was investigated, namely bis(oxalato)platinate, H2[Pt(C2O4)2]. The size evolution of the supported NPs, from the formation upon the Pt precursor decomposition on γ‐alumina to the sintering of the NPs at high temperatures, was followed by thermogravimetric analysis coupled with mass spectrometry (TG‐MS) and differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. A correlation between the NPs’ size of the catalyst and the performance for the CO, C3H6, C3H8 and NO oxidation reactions pointed out a retained activity during test cycles, showing low sensitivity to the test conditions applied (i. e., temperature and gas composition). The overall catalytic performance was better in the fresh catalysts compared to the reference catalyst prepared from platinum nitrate, Pt(NO3)4. In particular, the different dispersion of the Pt NPs over the support obtained from the two precursors was identified as the reason for the different catalytic performance, retaining small NPs size after the tests cycles.

Aerobic bacteria-supported biohybrid palladium catalysts for efficient cross-coupling reactions

Palladium-based catalysts are of key importance in organic synthesis due to their versatility and tolerance for a wide range of functional groups. However, their use challenged by increasing sustainability issues and complex preparation methods. Consequently, the development of new heterogeneous catalysts with enhanced sustainability is of significant interest. Typically, the synthesis of carbon supports for palladium is associated with high energy consumption or the generation of substantial chemical waste, prompting extensive research into the creation of sustainable biological supports. In this study, the potential use of aerobic bacterial cells as a support for palladium nanoparticles was explored, using Paracoccus yeei VKM B-3302 as a model organism. Electron microscopy, powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of palladium particles on the cell surface as well as inside microorganisms following deposition from a solution. Control experiments established that bacterial cells do not interact with either the reactants or the products of selected cross-coupling processes. Furthermore, bacteria do not affect the analysis of reaction mixtures by nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC–MS). At the same time, palladium/Paracoccus yeei demonstrated efficient catalysis of the Mizoroki-Heck and Suzuki-Miyaura reactions, yielding results comparable to commercial palladium on carbon (Pd/C) catalysts. Employing a fresh start procedure and catalyst separation method, the catalyst was successfully recycled and reused across five cycles, maintaining good catalytic activity. In a broader aspect, bacteria-supported biohybrid palladium catalysts can represent a new type of catalysts worth to explore in a number of processes, where sustainability issues are concerned.

New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH3

5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NOx with NH3 (NH3-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption, and NO + O2 reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO2 and N2O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu+ species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu+ species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a “double-edged sword” effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuOx–CeO2 strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe.

Unlocking green potential: Enhancing biomass valorization via thermal depolymerization with spent catalysts

Effective catalysts for the thermal depolymerization of biomass present an attractive way to reduce energy consumption. This study investigated the effect of spent ZSM-5 catalysts on product distribution through thermal catalytic depolymerization. The spent catalyst has similar properties to the commercial fresh catalysts, as assessed through characterization analysis. The utilization of spent catalysts can enhance the production of bio-oil. The bio-oil yields for rice straw, brown solid, alkaline, and dealkaline lignin by catalytic depolymerization are 11%, 31%, 6%, and 21%, respectively. Therefore, depolymerization using a spent catalyst is a promising method to degrade lignocellulose.

Dehydrogenation of ethylbenzene to styrene over magnesium-doped hematite catalysts

Styrene is an important building block of the plastics industry being produced by ethylbenzene dehydrogenation. The commercial catalysts have the disadvantages of deactivation by potassium loss and coke deposition, and chromium toxicity. To overcome these drawbacks, a new catalyst was developed by investigating the effect of magnesium on the catalytic properties of hematite in ethylbenzene dehydrogenation. Hematite was detected for all fresh catalysts and magnetite for the spent ones. Magnesium was found as magnesium ferrite and magnesium oxide, depending on the magnesium amount. Magnesium compounds affect the crystal sizes, the amount of defects and the reducibility of iron oxides, the predominance of each one depending on the composition of the solids. These effects caused important differences in activity, selectivity and stability of the catalysts. The catalyst with Mg/Fe = 0.09, consisting of aggregates of hematite, MgO and magnesium ferrite, showed the highest yield, being the most promising for commercial applications.

A framework for modeling of catalyst deactivation and coking free of main-reaction kinetics in methanol to gasoline process

Optimizing the methanol-to-gasoline technology necessitates a profound comprehension of catalyst deactivation and coke formation kinetics. However, conventional mathematical models cannot capture catalyst deactivation without relying on complex main-reaction kinetic models, and they treat the prediction of coking as a separate problem. Addressing these challenges, this research introduces a computational framework to identify the optimal model for the kinetics of deactivation and coking. The key novelty is leveraging the concept of active site loss to eliminate the requirement for main-reaction kinetic models while facilitating the prediction of coking according to the site loss model. Experimental data of an HZSM-5 catalytic bed under diverse operating conditions (WHSV: 10–100 h−1, temperature: 325–375 °C) were employed to validate method efficiency for predicting reactor outputs, including oxygenates, light olefins, and gasoline. The proposed approach demonstrates a 0.52 % Root-Mean-Square-Error in simulating product weights and a 66 % reduction in deactivation kinetic constants. This study reveals assuming a critical volume for each grown coke precursor justifies experimental data by R2 of 99.71 %. This volume was computed around 100 Å3 and exhibits a linear Arrhenius temperature dependency. These results highlight the high accuracy and extreme simplicity this framework offers. Moreover, the method transforms deactivated catalyst data at varying WHSVs into a larger unified dataset for the fresh catalyst at each isotherm. Hence, it also positively impacts the kinetic study of main reactions. Consequently, the developed framework is a promising tool for direct assessment of catalyst deactivation and coking in similar processes toward advancing catalyst design strategies and fuel production efficiency.

Reaction microkinetic model of xylose dehydration to furfural over beta zeolite catalyst

AbstractIn recent decades, there has been a growing interest in bio-refineries as a crucial element in transitioning to a low-carbon economy. One specific aspect of this interest is the conversion of carbohydrates into separate platform chemicals, such as furfural (FUR), which play a significant functional role in various daily life processes. This research paper focuses on investigating the use of a H-beta catalyst with SiO2/Al2O3 = 28 for producing furfural from xylose in water. Various conditions, such as temperature and initial solution concentration, are studied to determine their effect on FUR yield. The highest FUR yield (40 mol.%) is obtained when FUR is the only product species. We also report that about 90% yield from reaction with fresh catalyst can be achieved after catalyst regeneration. The activation energies for the reaction on the catalyst surface are found to be in the range of 38–75 kJ/mol. A mathematical kinetic model with three irreversible steps is derived to estimate the reaction sequence at 160, 180, and 200 °C. The model takes into account mechanisms such as adsorption, desorption, and transport (internal or external). Our results suggest that the H-beta catalyst shows high activity toward FUR yield and could be a promising alternative for mass-scale production of the latter.