Internal Mass Transfer Limitations Research Articles

Catalytic Dechlorination of Three Organochlorides by Recyclable Nano-Palladium-Engineered Natural Sponge with Formic Acid

Catalytic dechlorination of organic chlorides by palladium (Pd) with HCOOH represents one of the most effective and promising techniques for environmental remediation. In this study, we adopted alkaline-modified porous natural sponge as support of a Pd nanocatalyst (Pd@M-Sponge) and HCOOH as a hydrogen source for the hydrodechlorination of florfenicol (FF), o-chlorophenol (o-CP), and p-chlorophenol (p-CP). Favorable conversion efficiency of FF, o-CP, and p-CP was achieved at 25 °C and atmospheric pressure attributed to the small diameter and high catalytic reactivity of the prepared Pd NPs, in addition to the slight internal mass transfer limitation of the prepared Pd@M-Sponge. High reaction rate constants were obtained even in the conditions of a low molar ratio of HCOOH to p-CP (10:1) and a high concentration of p-CP (500 mg/L). The prepared catalyst also demonstrated superior recyclability without any obvious decrease in catalytic reactivity in 20 successive p-CP dechlorination cycles. This work provides an ideal recyclable and cost-effective catalyst based on renewable and biocompatible natural material for the catalytic hydrodechlorination of chlorinated organic pollutants with formic acid and a new view for the exploration and designing of highly reactive and stable catalysts for hydrodechlorination.

Optimization of an Open-Cell Foam-Based Ni-Mg-Al Catalyst for Enhanced CO2 Hydrogenation to Methane

In the presented work, the catalytic performance of a nickel catalyst, in CO2 hydrogenation to methane, within a ZrO2 open-cell foam (OCF)-based catalyst was studied. Two series of analogous samples were prepared and coated with 100–150 mg of a Mg-Al oxide interface to stabilize the formation of well-dispersed Ni crystallites, with 10–15 wt% of nickel as an active phase, based on 30 ppi foam or 45 ppi foam. The main factor influencing catalytic performance was the geometric parameters of the applied foams. The series of catalysts based on 30 ppi OCF showed CO2 conversion in the range of 30–50% at 300 °C, while those based on 45 ppi OCF resulted in a significantly enhancement of the catalytic activity: 90–92% CO2 conversion under the same experimental conditions. Calculations of the internal and external mass transfer limitations were performed. The observed difference in the catalytic activity was primarily related to the radial transport inside the pores, confirmed with the explicitly higher conversions.

Modeling of a catalytic fluidized bed reactor via coupled CFD-DEM with MGM: From intra-particle scale to reactor scale

The Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) method is extended by coupling with the multi-grain model (MGM) to include particle growth due to a gas-solid reaction, as well as intra- and inter-particle phenomena such as heat and mass transfer, and reaction, next to the inter-particle and fluid-particle interactions in the reactor. This comprehensive model treats each particle individually and accounts for changes in particle properties due to both the particle growth and temporal and spatial variations of the process conditions. It also captures the impact of the change in the particles' properties on the fluidized bed reactor characteristics, such as the hydrodynamic regime. The results of the model revealed that the fluidization characteristics and solids mixing can be altered by particle growth. Particle growth also led to the formation of a particle size gradient along the height of the reactor. The coupling allows for monitoring of both external and internal mass transfer limitations. For the adopted reaction kinetics, growth rate and properties the external mass transfer limitations remained negligible, however the internal mass transfer limitation plays a significant role in the process performance.

Utilization of Salmon fish bone wastes as a novel bio-based heterogeneous catalyst-support toward the production of biodiesel: Process optimizations and kinetics studies

This study investigated the feasibility of using calcined Salmon fish bone wastes as an inexpensive and reusable catalyst-support for the biodiesel production via transesterification of sunflower oil. In this venue, a series of catalysts were synthesized by impregnating potassium hydroxide (KOH) onto the calcined Salmon fish bones. The as-prepared catalysts were characterized through several techniques, including the FESEM, BET-BJH, TGA, FT-IR, and XRD. In this regard, the effects of the calcination temperature of the waste Salmon fish bone, KOH loading amount, and the calcination temperature of KOH-impregnated support upon the catalytic activity of the final catalyst were understudied. Results displayed that the calcination temperature of fish bones at 1273 K with 40 wt% of KOH loading, which was calcined at 873 K, led to the highest catalytic performance. For this optimum material, the effects of the parameters, such as the catalyst loading, the methanol: oil molar ratio, and the reaction time and temperature upon the biodiesel production yield were examined. It was determined that the optimum operating conditions for the reaction included the catalyst loading of 10 wt%, the methanol: oil molar ratio of 10:1, and the reaction temperature of 338 K for 3 h. The gas chromatography and 1HNMR analyses revealed an optimum biodiesel production yield of 99.13 %. This result is attributed in part to a rather high basicity of the aforementioned optimum material. Moreover, this optimum species was shown to endure four consecutive reaction cycles, whereas its activity dropped by about 10 %. Furthermore, the chemical kinetic parameters of the reaction using this catalyst were determined to be; the reaction rate constant of 0.45 h−1 and its respective activation energy of 67.01 kJ/mol. Ultimately, it was demonstrated that neither internal nor external mass transfer limitations existed in the heterogeneous system considered in this research hence, all observed behaviors were solely due to chemical kinetics.

Enhancing Kerosene Selectivity of Fischer-Tropsch Synthesis by Periodical Pore Drainage Via Hydrogenolysis

Accumulation of wax inside the catalyst pores during transient cobalt-catalyzed Fischer-Tropsch synthesis (FTS) leads to unfavorable product distribution and low activity by imposing internal mass transfer limitations. The condensation of paraffin severely changes the apparent product stream that actually leaves the reactor before the catalyst pores are filled completely and the steady state is reached. Thus, the product distribution of the transient FTS is less complex than expected in comparison to the steady-state FTS and increasingly consists of hydrocarbons (HCs) with an average chain length in the range of kerosene (C<sub>9</sub>-C<sub>17</sub>). So, in order to prevent FTS from reaching a steady state, the pores are drained periodically by hydrogenolysis (HGL). The alternating HGL is realized by a switch from syngas (H<sub>2</sub>, CO) to pure hydrogen at a reaction temperature in the range of 210°C to 240°C. The alternating process leads to an improvement in kerosene selectivity of 48%, 37%, and 28% at 210°C, 220°C and 240°C, respectively. Furthermore, the influence of temperature on the hydrogenolysis of long-chain HCs was experimentally investigated. It was found that temperature affects methane selectivity severely. A high hydrogenolysis temperature is favorable as this leads to a severely decreased overall methane selectivity and, thus to a higher production rate of alkanes within the carbon number range of 9 to 17.

An investigation of the catalytic performance of Fe–Mn/Al2O3 nanocatalyst for light olefins production using RSM method and kinetic study

AbstractThe Fe–Mn/Al2O3 nanocatalysts were manufactured via the sol‐gel procedure and were evaluated for Fischer–Tropsch synthesis. The impact of different operational parameters of T, P, and H2/CO ratio on the catalytic performance for light olefins production has been studied using response surface methodology (RSM). Furthermore, the optimization and modeling of selected responses were also carried out via RSM and historical data design type of DOE; and the best process conditions were found to be T = 365°C, H2/CO = 1.50, and P = 1.50 bar. The mechanism of CO hydrogenation reaction over the Fe–Mn/Al2O3 nanocatalysts was also investigated using the non‐linear regression method. It was found that the mechanism of the CO hydrogenation reaction is based on the Eley–Rideal type and the best‐fitted equation for this mechanism was found to be −rCO = KPCOPH2/1+αPCO. The obtained value of activation energy (85.20 kJ mol−1) affirmed the absence of internal mass transfer limitations. The physico‐chemical properties of the samples were investigated by various techniques of XRD, BET, TPR, TGA, and DSC.

Intracellular accumulation of c-di-GMP and its regulation on self-flocculation of the bacterial cells of Zymomonas mobilis.

Zymomonas mobilis is an emerging chassis for being engineered to produce bulk products due to its unique glycolysis through the Entner-Doudoroff pathway with less ATP produced for lower biomass accumulation and higher product yield. When self-flocculated, the bacterial cells are more productive, since they can self-immobilize within bioreactors for high density, and are more tolerant to stresses for higher product titers, but this morphology needs to be controlled properly to avoid internal mass transfer limitation associated with their strong self-flocculation. Herewith we explored the regulation of cyclic diguanosine monophosphate (c-di-GMP) on self-flocculation of the bacterial cells through activating cellulose biosynthesis. While ZMO1365 and ZMO0919 with GGDEF domains for diguanylate cyclase activity catalyze c-di-GMP biosynthesis, ZMO1487 with an EAL domain for phosphodiesterase activity catalyzes c-di-GMP degradation, but ZMO1055 and ZMO0401 contain the dual domains with phosphodiesterase activity predominated. Since c-di-GMP is synthesized from GTP, the intracellular accumulation of this signal molecule through deactivating phosphodiesterase activity is preferred for activating cellulose biosynthesis to flocculate the bacterial cells, because such a strategy exerts less perturbance on intracellular processes regulated by GTP. These discoveries are significant for not only engineering unicellular Z. mobilis strains with the self-flocculating morphology to boost productionbut also understanding mechanism underlying c-di-GMP biosynthesis and degradation in the bacterium.

Calculation of Mass Transfer Limitations for a Gas-Phase Reaction in an Isothermal Fixed Bed Reactor: Tutorial and Sensitivity Analysis

The study of the reactivity of catalysts requires one to assess chemical kinetics and mechanisms in the absence of mass transport artifacts. Despite the existence of models and criteria for assessing the presence of mass transfer limitations during catalytic tests for gas-phase reactions in isothermal fixed bed reactors, the literature does not present straightforward protocols for performing the latter calculations. In this work, we present a systematic protocol for the calculations above. Particularly, we present protocols for estimating the effectiveness factor for external and the Weisz-Prater number for the internal mass transfer limitations. Data previously published on the oxidation of propane over mixed vanadium–aluminum (hydr)oxides was taken as a case study. Based on these protocols, we did a sensitivity study of the models used for calculations. Results showed that the model for calculating the effectiveness factor was poorly sensitive to all the above modifications. Meanwhile, the Weisz-Prater number was much more sensitive to the studied modifications, even reaching deviations up to ∼200%.

Pore-size dependent catalytic activity of supported Pd catalysts for selective hydrogenation of nitrile butadiene rubber

Pore diffusion effect plays a crucial role in heterogeneous hydrogenation of unsaturated polymers. However, how large pore size can eliminate the pore diffusion limitation remains a controversial issue. Herein, we prepared a series of Pd/SiO2 catalysts with graded pore sizes and investigated the effect of pore size on hydrogenation activity of nitrile butadiene rubber (NBR). It is found that when the catalyst pore size (Dcat) is 7 times of the diameter of NBR chains (DNBR), the Weisz modulus Φ can be reduced to < 0.3 thus the internal mass transfer limitation can be eliminated, making NBR easier to approach the active sites. Consequently, the catalysts with the Dcat/DNBR > 7 exhibit excellent catalytic activity (96.7%) and selectivity (100%) to C = C. This work emphasizes that the pore size of catalysts can regulate the pore transfer limitation and the accessibility of internal active sites, providing useful guidance for the design of efficient macromolecular hydrogenation catalysts.

Enhancement of Fischer-Tropsch Synthesis by Periodical Draining of the Wax-Filled Pores of a Cobalt Catalyst by Hydrogenolysis

Fischer-Tropsch reactors operated in a steady state suffer from a low pore effectiveness factor and a high methane selectivity caused by internal mass transfer limitations due to the accumulation of long-chain hydrocarbons inside the catalyst pores. Therefore, an alternating process switching between Fischer-Tropsch synthesis (FTS) and drainage of the pores by hydrogenolysis is proposed. The periodical cracking of the accumulated waxes within the (partially) filled pores, realized by a switch from syngas (H&lt;sub&gt;2&lt;/sub&gt;, CO) to pure hydrogen, results in a higher overall catalyst productivity and a more favorable product distribution. The influence of temperature and time of FTS on drainage time and product distribution was experimentally investigated at typical temperatures of FT fixed bed processes in a range of 210 to 240°C. Alternating drainage of the pores by hydrogenolysis at a hydrogen partial pressure of just 1 bar leads to an improvement of the rate of CO conversion by up to 90% (240°C, 2 h FTS) and an improvement of even 120% concerning the rate of production of non-methane hydrocarbons (240°C, 2 h FTS).

Dimethyl ether low-temperature catalytic oxidation over Rh/Al2O3 in a stagnation-flow reactor

Dimethyl ether (DME) is a promising fuel for use in low-temperature portable hydrogen production, domestic applications, or diesel engines. It burns with less emissions than conventional fuels and has properties similar to LPG in terms of storage and transport, rendering it effective in many strategies for combating climate change. In this study we investigated the partial and total oxidation of DME over 5 wt% Rh/Al2O3 at low temperatures (215 to 320 °C), relevant to portable and domestic energy applications as well as the after-treatment systems of DME-powered engines. We captured the effects of temperature, flow rate, and inlet feed composition on the reactivity. For partial oxidation, we utilized the stagnation-flow reactor geometry to isolate the oxidation zone from the reforming zone. We discuss the reaction order with respect to DME and O2 and provide activation energy values under kinetics control. We also provide data where internal and external mass transfer limitations are present to examine the diffusive-convective transport near the catalyst surface, not easily done in three-dimensional environments such as packed beds. The experimental data we provide here pave the way for accurate kinetic modeling of DME partial and total oxidation on Rh/Al2O3, for reactor design and optimization as well as rational catalyst design.

Kinetics and hydrodynamics of Candida antartica lipase-catalyzed synthesis of glycerol dioleate (GDO) in a continuous flow packed-bed millireactor

Diacylglycerols (DAG) have been widely used in many industries due to their remarkable capabilities as emulsifiers and stabilisers. However, developing a sustainable and an effective synthesis method for DAG remains a challenge. Continuous flow bio-reactor is recognized to be more productive, controllable, and reliable instrument for developing green and intensified processes. In this work, a continuous flow packed bed millireactor was employed for the synthesis of glycerol dioelate (GDO) catalyzed by immobilized lipase namely Candida antartica. Experiments were carried out to evaluate the kinetic parameters as well as to assess the internal and external mass transfer limitations. Using one-factor-at-a-time variables method, maximum oleic acid conversion and GDO selectivity were achieved at 85% and 74% respectively, at 0.15 g of lipase, 77 min of residence time with 1.6:1 molar ratio of oleic acid/glycerol. Hydrodynamic studies showed that the esterification reaction is kinetically controlled and unaffected by external and internal mass transfer. Employing Lilly–Hornby model for kinetic evaluation, Km values increased with increasing flow rates, whereas, Vmax appeared to be flow rate independent. Reusability tests revealed that the activity of immobilized lipase remained the same after 9 successive reaction cycles. At 11 days of operation, the stability of the lipase in the continuous packed bed millireactor decreased only 5–7%, indicating satisfying operational results and recyclability. This work may promote the enzymatic engineering synthesis of DAG, facilitating the creation of a cleaner and safer process. It has the potential to broaden the application of enzymes in continuous flow micro or millireactors.

Evaluating catalytic (gas–solid) spectroscopic cells as intrinsic kinetic reactors: Methanol-to-hydrocarbon reaction as a case study

Commercial spectroscopic gas–solid cell reactors are routinely used to analyze the dynamics of the catalyst (catalyst pelletized as a disc) structure and retained/adsorbed species using multiple operando techniques. These instruments have revolutionized the understanding of many catalytic reactions, including the methanol-to-hydrocarbon reactions. We propose a reaction engineering framework to evaluate spectroscopic cells based on (a) analyzing the fluid dynamic performance, (b) comparing their performance with a reference packed-bed reactor, and (c) the assessment of the external and internal mass transfer limitations. We have used a Specac HTHP and a Linkam THMS600 cell reactors coupled with the corresponding gas conditioning, spectroscopic, and mass spectrometry apparatuses. Our results reveal that these cells approach a perfect mixing only with several equivalent tanks in series and they are reliable at low catalyst loadings (thin disc) and high flowrates (low spacetimes). Under these conditions, we can avoid external-internal mass transfer limitations and fluid dynamic artifacts (e.g., bypassing or dead/stagnant volume zones), obtaining intrinsic kinetics with the corresponding operando spectroscopic signatures. The proposed methodology allows to understand the influence of process parameters and potential design modifications on the observed kinetic performance.

Nano-engineered natural sponge as a recyclable and deformable reactor for ultrafast conversion of pollutants from water

An alkaline-modified natural sponge was applied as support of gold and silver nanocatalysts and a deformable reactor to hold the reaction solution, quickly adsorb several kinds of environmental pollutants (4-nitrophenol, hexavalent chromium, and methyl orange) and efficiently catalyse their conversion. As the reaction solution is sustained in the connecting micro-pores constructed by the stretched and knotted sponge fibers, the catalytic reaction is free from external mass transfer and suffers slight internal mass transfer limitation. This batch-wise reaction system employing an operation procedure of injection-extrusion achieved a nearly complete conversion of the reactants within 1 min or much less. This compressible support can also be packed in a continuous flow reaction system and can be repeated use for 37 times without any loss of catalytic activity. This study provides a generalizable and straightforward strategy for utilizing deformable soft supports that may inspire some unique industrial applications.

Tunable HMF hydrogenation to furan diols in a flow reactor using Ru/C as catalyst

• The hydrogenation of HMF to furan diols was studied and optimized in flow reactor. • The commercial Ru/C was an efficient catalyst for the BHMF and BHMTHF synthesis. • The highest BHMF and BHMTHF yields were ascertained only tuning the contact time. • The catalyst was stable up to 6 h and easily reactivable through acetone washing. • Internal mass transfer limitations occurred and affected the overall reaction rate. 5-hydroxymethylfurfural (HMF), accessible from various feedstocks, represents an important renewable platform-chemical, precursor for valuable biofuels and bio-based chemicals. In this work, the continuous hydrogenation of an aqueous solution of HMF to give strategic monomers, 2,5-bis(hydroxymethyl)furan (BHMF) and 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) was investigated in a continuous flow reactor adopting a commercial Ru/C (5 wt%) as catalyst. The influence of the main process variables on products yield and selectivity was studied and optimized. The highest BHMF and BHMTHF yields of 87.9 and 93.7 mol%, respectively, were achieved by tuning the catalyst contact time, keeping all other variables constant (temperature, pressure, hydrogen flow rate, initial HMF concentration). Intraparticle diffusion limitation for hydrogen and HMF was shown to occur at some of the tested conditions by performing the HMF hydrogenation with different catalyst particle sizes, confirmed by calculations. Constant catalyst activity was observed up to 6 h time-on-stream and then gradually reduced. Fresh and spent catalyst characterization showed no significant sintering and negligible leaching of ruthenium during time-on-stream. A decrease of the specific surface area was observed, mainly due to humin deposition which is likely the reason for catalyst deactivation. Catalyst performance could be restored to initial values by a thorough washing of the catalyst.

Investigating the effects of substrate morphology and experimental conditions on the enzymatic hydrolysis of lignocellulosic biomass through modeling

BackgroundUnderstanding how the digestibility of lignocellulosic biomass is affected by its morphology is essential to design efficient processes for biomass deconstruction. In this study, we used a model based on a set of partial differential equations describing the evolution of the substrate morphology to investigate the interplay between experimental conditions and the physical characteristics of biomass particles as the reaction proceeds. Our model carefully considers the overall quantity of cellulase present in the hydrolysis mixture and explores its interplay with the available accessible cellulose surface.ResultsExploring the effect of various experimental and structural parameters highlighted the significant role of internal mass transfer as the substrate size increases and/or the enzyme loading decreases. In such cases, diffusion of cellulases to the available cellulose surface limits the rate of glucose release. We notably see that increasing biomass loading, while keeping enzyme loading constant should be favored for both small- (R < 300 mu m) and middle-ranged (300 < R < 1000 mu m) substrates to enhance enzyme diffusion while minimizing the use of enzymes. In such cases, working at enzyme loadings exceeding the full coverage of the cellulose surface (i.e. eI>1) does not bring a significant benefit. For larger particles (R > 1000 mu m), increases in biomass loading do not offset the significant internal mass transfer limitations, but high enzyme loadings improve enzyme penetration by maintaining a high concentration gradient within the particle. We also confirm the well-known importance of cellulose accessibility, which increases with pretreatment.ConclusionsBased on the developed model, we are able to propose several design criteria for deconstruction process. Importantly, we highlight the crucial role of adjusting the enzyme and biomass loading to the wood particle size and accessible cellulose surface to maintain a strong concentration gradient, while avoiding unnecessary excess in cellulase loading. Theory-based approaches that explicitly consider the entire lignocellulose particle structure can be used to clearly identify the relative importance of bottlenecks during the biomass deconstruction process, and serve as a framework to build on more detailed cellulase mechanisms.

Decomposition of Additive-Free Formic Acid Using a Pd/C Catalyst in Flow: Experimental and CFD Modelling Studies

The use of hydrogen as a renewable fuel has gained increasing attention in recent years due to its abundance and efficiency. The decomposition of formic acid for hydrogen production under mild conditions of 30 °C has been investigated using a 5 wt.% Pd/C catalyst and a fixed bed microreactor. Furthermore, a comprehensive heterogeneous computational fluid dynamic (CFD) model has been developed to validate the experimental data. The results showed a very good agreement between the CFD studies and experimental work. Catalyst reusability studies have shown that after 10 reactivation processes, the activity of the catalyst can be restored to offer the same level of activity as the fresh sample of the catalyst. The CFD model was able to simulate the catalyst deactivation based on the production of the poisoning species CO, and a sound validation was obtained with the experimental data. Further studies demonstrated that the conversion of formic acid enhances with increasing temperature and decreasing liquid flow rate. Moreover, the CFD model established that the reaction system was devoid of any internal and external mass transfer limitations. The model developed can be used to successfully predict the decomposition of formic acid in microreactors for potential fuel cell applications.

Non-equimolar transient grain model for CO2-gasification of single biomass char pellet

Gasification of solid substances involves complex processes that inculpates non-catalytic heterogeneous interactions. These interactions are significantly influenced by heat and mass transfer limitations resulting into large differences in actual and intrinsic rate of reaction. In the present work, a non-isothermal transient mathematical formulation, based on grain model, is developed to capture the effect of heat and mass transfer limitations for the CO2-gasification of single raintree char pellet. For kinetic rate law, conventional unreacted shrinking core model is modified by introducing a parameter that appreciated the catalytic effect of mineral content. The kinetic parameters were estimated by the non-linear regression analysis. The activation energies were estimated to be E = 122.37 kJ/mol/K and E1 = 176.94 kJ/mol/K for semi-empirical modified SCM. The total conversion time dropped by 32 min on increasing the ash content of char from 0% to 10% which is quite significant indicating that ash is highly catalytic in nature. A CFD software COMSOL Multiphysics 5.4 is used to solve the governing set of partial differential equations. The pellet model is validated by comparing the model results with the experimental results and a good agreement was realized. The experimental results are obtained by performing gasification experiments for a single char pellet at three different temperatures. The concept of effectiveness factor is explored to quantify the effect of internal mass and heat transfer limitations. The effectiveness factor was found to be more or less constant for a wide range of conversion and decreasing with increasing pellet radius.

Rationally Constructing A Nano MOF-Derived Ni and CQD Embedded N-Doped Carbon Nanosphere for the Hydrogenation of Petroleum Resin at Low Temperature.

A key issue in attaining highly efficient supported catalysts for the hydrogenation of unsaturated polymers arises from the entanglement between the number of exposed active sites and the severe internal mass transfer limitation caused by their large molecular size. Hence, an ultrasmall N-doped carbon nanosphere with Ni NPs and CQDs embedded (Ni-CQDs/NCNs) was reasonably constructed by low-temperature (400 °C) pyrolysis of the precursor CQDs@Nano-Ni-ZIFs. As-prepared Ni-CQDs/NCNs exhibited superior catalytic activity to a commercial 10% Pd/C catalyst in petroleum resin hydrogenation under a low temperature of 150 °C, which is 100 and 60 °C lower than that of previously reported Ni- and Pd-based catalysts, respectively. The excellent catalytic activity of Ni-CQDs/NCNs mainly contributes to the following factors: first, its ultrasmall structure (ca. 50 nm) eliminates the internal mass transfer limitation; second, the CQDs and N-doped carbon matrix stabilize the 53.1 wt % high-loading Ni NPs at a small size of 5.6 nm, providing abundant active sites; and third, the electronic regulation of N-doped carbon enhances the intrinsic activity of Ni, which was revealed by the experiments and DFT calculations. Besides, Ni-CQDs/NCNs exhibits long-term stability and appreciable magnetic separation performance, making it a considerable candidate for industrial application. This work not only offers a facile approach to prepare nano MOF-derived catalysts but also gives helpful instruction to the rational design of heterogeneous catalysts for the reaction involving large molecules.

An assessment on kinetic modeling of esterification reaction from oleic acid and methyl acetate over USY zeolite

In this work, commercial USY Zeolite was employed in oleic acid with methyl acetate esterification. Kinetic studies of esterification were carried out at methyl acetate to the oleic acid molar ratio of 10:1, with 5 wt% and 10 wt% of catalyst content and at 453, 473, 493 and 513 K. The Pseudo-homogeneous (PH) and Heterogeneous kinetic models, according to the Eley-Rideal (ER) and the Langmuir-Hinshelwood (LH) mechanisms, were investigated to correlate experimental data. The Thiele modulus analysis confirmed that the effect of the pore sizes on the internal mass transfer limitations could be neglected, and the study of the internal and external mass transfer limitations showed that the chemical reaction is the rate-controlling step. The coefficient of determination (R 2 ), the Akaike's information criterion (AIC), the relative Akaike weight (λ i ), and Spearman's rank correlation coefficient ( ρ i , j ) were utilized to evaluate the kinetic model's adequacy. The PH model provided the best results according to Akaike's information criterion (AIC) and relative Akaike weight (λ i ). Spearman's rank correlation coefficient ( ρ i , j ) showed that some parameters of ER and LH models presented high correlation and confidence intervals in their parameters, not satisfactorily representing the observed kinetic data. The thermodynamic study through PH model shows that oleic acid with methyl acetate esterification is an endothermic (ΔH = 59.83 kJ mol −1 ) and endergonic (ΔG = 118.66–126.45 kJ mol −1 ) reaction. The activation energy ( E a ) was 41.77 kJ mol −1 , and the negative value of entropy variation (ΔS = −129.8 J mol −1 K −1 ) might be associated with its associative mechanism. The decrease of catalyzed activation energy compared to the uncatalyzed reaction indicates that the USY zeolite was active to the esterification of oleic acid with methyl acetate. • USY zeolite was active in the esterification reaction with methyl acetate. • Three kinetic models were assessed and fitted well to experimental data. • Effect of pore sizes on the internal mass transfer limitations could be neglected. • Statistical criterion discriminated overparametrized models and unreliable parameters. • Pseudo-Homogeneous model was the most suitable.