External Mass Transfer Limitations Research Articles

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.

On the reduction of NiFe/Al2O3 oxygen carrier in high-pressure chemical looping applications

Chemical looping represents a promising technology with various applications ranging from clean power production to alternative syngas production. In this work, two oxygen carriers with different Ni loadings (4.3% wt. and 12% wt.) and similar Fe loadings (9.9% wt. and 8.5% wt.) are synthesized through a co-precipitation/impregnation route and tested in two thermogravimetric analyzers. Firstly, the effect of temperature (700–900 °C) on the oxygen transport capacity and reduction conversion of both materials is assessed at ambient pressure (0.5 nl/min with 20% H2/N2). The influence of material loading is also studied, and it is shown that higher Ni loadings provide a significant improvement in material activity. A complete reduction conversion is achieved at 900 °C and ambient pressure. At high pressure (10–20 bar), tests are carried out in a temperature range of 700–850 °C. The effect of flow rate (2 nl/min to 6 nl/min with 50% H2/N2) is first assessed to prevent external mass transfer limitations. Higher total pressures have a negative effect on reduction kinetics, while higher Ni loadings demonstrate increased final reduction conversion also at high pressure, reaching about 75% conversion after 20 min. The long-term cyclability of the material is also investigated both at low (100 cycles) and high pressure (80 cycles) conditions and a conversion gain is observed throughout the cycles in both cases. No changes in the material microstructure are observed after 80 high-pressure cycles.

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.

Kinetics of H2S removal using alkaline residue as in-bed sorbent in fluidized bed gasification of biomass and wastes

The use of alkaline residue from the acetylene industry (carbide slag, CS) as in-bed sorbent to remove H2S from syngas from biomass/waste fluidized bed (FB) gasification was investigated. Measurements were conducted in a laboratory FB applying differential conversion technique, tracking the reaction using both gas measurements and solid analysis. Apparent reaction kinetics was obtained, without external mass transfer limitations, for different gas mixtures containing CO2, H2O, CO, H2 and CH4, having relatively low H2S concentration (500–1000 ppm). The addition of CO2 and H2O to an N2-H2-H2S mixture showed that the reaction rate was reduced in the presence of these species. Varying the H2 concentration between 7 and 14% in simple (N2-H2-H2S) reactive gas mixtures did not affect the results, while both CO and H2 potentially affected the reaction rate if also CO2 was present in the gas. Other operating parameters, such as sorbent particle size, sulfidation- and calcination temperature also affected the CaO sulfidation rate, which increased with temperature between 800 and 900 °C and was enhanced by higher calcination temperature. Specific surface area and pore size distribution of the calcined CS was measured before and after the sulfidation reaction, showing that CS maintained a large fraction of its original pore volume even after most of the CaO had been converted into CaS. The sulfidation rate of calcined limestone was also measured for comparison showing that the reaction rate using CS was slightly lower, but similar to that using limestone, showing that CS is a promising alternative to conventional calcium-based sorbents for high temperature H2S removal, contributing to promote the circular economy, while avoiding the current stacking of CS at the acetylene production sites.

Influence of the Distance between Two Catalysts for CO2 to Dimethyl Ether Tandem Reaction

AbstractTandem reactions, with their great potential for reduction of capital and operational costs, reaction time, and byproducts are becoming more prominent. Among possible tandem reaction systems for direct conversion of CO2 to green fuel, dimethyl ether synthesis via methanol route is of vital importance. However, there are several parameters which must be considered for the combination of two catalysts to achieve promising performance, of those, the distance between the two catalysts is a crucial one. This distance can affect the overall performance of the tandem system by causing external mass transfer limitations or the poisoning of the catalysts. This work presents a systematic study on the influence of the distance between the two catalysts for the CO2 to dimethyl ether tandem system.

An analytical solution of the effectiveness factor of photocatalytic reactors based on Robin boundary conditions

An analytical expression of the effectiveness factor of photocatalytic reactors that accounts for external mass transfer limitations is presented. The solution is based on Robin boundary conditions introducing the Sherwood number as the parameter that accounts for the external mass transfer limitations. Regions highlighting free diffusion, diffusion limitations, and external mass transfer limitations are identified based on the Thiele Modulus and the Sherwood number. At low values of the Sherwood number, the internal diffusion and reaction rate-limiting regions are surpassed by the external mass transfer limitations. A cut-off value of the Sherwood number below which external mass transfer limitations cannot be ignored is 0.55. The evaluation of the model showed that under Dirichlet boundary condition the model converges to literature models from similar studies. This 1-D model looked at the Sherwood number across a broad scope and accounted for a broader range of limitations associated with immobilized photocatalytic films.

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.

Synthesis of Ibuprofen Monoglyceride Using Novozym®435: Biocatalyst Activation and Stabilization in Multiphasic Systems

This work was focused on the enzymatic esterification of glycerol and ibuprofen at high concentrations in two triphasic systems composed of toluene+ibuprofene (apolar) and glycerol or glycerol–water (polar) liquid phases, and a solid phase with the industrial immobilized lipase B from Candida antarctica named Novozym®435 (N435) acting as the biocatalyst. Based on a preliminary study, the concentration of the enzyme was set at 30 g·L−1 and the stirring speed at 720 r.p.m to reduce external mass transfer limitations. To obtain more information on the reaction system, it was conducted at a wide range of temperatures (50 to 80 °C) and initial concentrations of ibuprofen (20–100 g·L−1, that is, 97 to 483 mM). Under these experimental conditions, the external mass transfer, according to the Mears criterion (Me = 1.47–3.33·10−4 << 0.15), was fast, presenting no limitation to the system productivity, regardless of the presence of water and from 50 to 80 °C. Considering that the enzyme is immobilized in a porous ion-exchange resin, limitations due to internal mass transfer can exist, depending on the values of the effectiveness factor (η). It varied from 0.14 to 0.23 at 50 to 80 °C and 0.32–1 mm particle diameter range in the absence of water, and in the same ranges, from 0.40 to 0.66 in the presence of 7.4% w/w water in the glycerol phase. Thus, it is evident that some limitation occurs due to mass transfer inside the pores, while the presence of water in the polar phase increases the productivity 3–4 fold. During the kinetic study, several kinetic models were proposed for both triphasic reacting systems, with and without first-order biocatalyst deactivation, and their fit to all relevant experimental data led to the observation that the best kinetic model was a reversible hyperbolic model with first-order deactivation in the anhydrous reaction system and a similar model, but without deactivation, for the system with added water at zero time. This fact is in sharp contrast to the use of N435 in a water-glycerol monophasic system, where progressive dissolution of ibuprofen in the reacting media, together with a notable enzyme deactivation, is observed.

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.

Structured Reactors Based on 3D Fe/SiC Catalysts: Understanding the Effects of Mixing.

The application of structured reactors provides a number of advantages in chemical processes. In this paper, two different three-dimensional (3D) Fe/SiC catalysts with a square cell geometry have been manufactured by Robocasting: monoliths (D = 14 and H = 15 mm) and meshes (D = 24 and H = 2 mm) and studied in the catalytic phenol oxidation by hydrogen peroxide (H2O2) for the sustainable production of dihydroxybenzenes (DHBZ). The fluid dynamics, catalytic performance, reaction rates, external mass transport limitation, and catalyst stability have been compared in three different reactors, monolithic fixed-bed reactor, multimesh fixed-bed reactor, and monolithic stirrer reactor, at selected operating conditions. The results show that the mechanical stirring of the 3D Fe/SiC monoliths avoids the external mass transfer limitation caused by the presence of oxygen bubbles in the channels (produced from the HO x · species in autoscavenging radical reactions). In addition, the backmixing has a positive effect on the efficient consumption of H2O2 but an adverse effect on the phenol selectivity to DHBZ since they are overoxidized to tar products at longer contact times. On the other hand, the wall porosity, and not the backmixing, affects the susceptibility of the 3D Fe/SiC catalyst to the Fe leaching, as occurs in the mesh structures. In conclusion, the monoliths operating under plug-flow and external mass transfer limitation in the monolithic fixed-bed reactor (MFB) provide an outstanding phenol selectivity to DHBZ and catalyst stability.

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.

Theoretical analyses of NH3‐SCR reaction‐mass transfer over Cu‐ZSM‐5

AbstractNH3‐selective catalytic reduction (NH3‐SCR) is a very effective technical means to control NOx emissions from diesel engines, and Zeolite Selony Mobil No. 5 (SiO2/Al2O3 ratio 53:1) ion exchanged with Cu (Cu‐ZSM‐5) provides support for the high performance of NH3‐SCR within a wide temperature window under diesel engine operating conditions. The mechanism of the NH3‐SCR reaction based on Cu‐ZSM‐5 is established. Resistance analysis, effective factor analysis, and characteristic time analysis are used to analyze the influence of external mass transfer limitation and washcoat diffusion limitation on NH3‐SCR reaction and the transition between the washcoat diffusion control regime, the external mass transfer control regime, and the kinetic control regime of the NH3‐SCR over Cu‐ZSM‐5. It provides the basis for the optimization of the catalyst structure and the support for the improvement of NH3‐SCR performance.

Mass Transfer in Hierarchical Silica Monoliths Loaded With Pt in the Continuous-Flow Liquid-Phase Hydrogenation of p-Nitrophenol

Sol-gel-based silica monoliths with hierarchical mesopores/macropores are promising catalyst support and flow reactors. Here, we report the successful preparation of cylindrically shaped Pt-loaded silica monoliths (length: 2 cm, diameter: 0.5 cm) with a variable mean macropore width of 1, 6, 10, or 27 μm at a fixed mean mesopore width of 17 nm. The Pt-loaded monolithic catalysts were housed in a robust cladding made of borosilicate glass for use as a flow reactor. The monolithic reactors exhibit a permeability as high as 2 μm2 with a pressure drop below 9 bars over a flow rate range of 2–20 cm3 min−1 (solvent: water). The aqueous-phase hydrogenation of p-nitrophenol to p-aminophenol with NaBH4 as a reducing agent was used as a test reaction to study the influence of mass transfer on catalytic activity in continuous flow. No influence of flow rate on conversion at a fixed contact time of 2.6 s was observed for monolithic catalysts with mean macropore widths of 1, 10, or 27 µm. As opposed to earlier studies conducted at much lower flow velocities, this strongly indicates the absence of external mass-transfer limitations or stagnant layer formation in the macropores of the monolithic catalysts.

3,5-Dinitrosalicylic Acid Adsorption Using Granulated and Powdered Activated Carbons.

Some nitroaromatic compounds are found in wastewater from industries such as the weapons industry or the wine industry. One of these compounds is 3,5-dinitrosalicylic acid (DNS), widely used in various tests and frequently found as an emerging pollutant in wastewater and to which the required attention has not been given, even though it may cause serious diseases due to its high toxicity. This study investigated the adsorption of DNS using granulated activated carbon (GAC) and powdered activated carbon (PAC) at different temperatures. The results show that in equilibrium, the adsorption takes place in more than one layer and is favorable for the removal of DNS in both GAC and PAC; The maximum adsorption capacity was obtained at 45 °C, with values of 6.97 mg/g and 11.57 mg/g, respectively. The process is spontaneous and exothermic. In addition, there was a greater disorder in the solid-liquid interface during the desorption process. The predominant kinetics using GAC (7.14 mg/g) as an adsorbent is Elovich, indicating that there are heterogeneous active sites, and when PAC (10.72 mg/g) is used, Pseudo-second order kinetics predominate, requiring two active sites for DNS removal. External mass transfer limitations are only significant in GAC, and ATR-FTIR studies in PAC demonstrated the participation of functional groups present on the adsorbent surface for DNS adsorption.

Effects of stagnant zone on the effectiveness factor in a trickle bed

Industrial trickle-bed reactors are normally operated under complete wetting conditions, almost 20–30% of the particle external surface is covered by stagnant liquid. To investigate the influence of stagnant zone on the effectiveness factor, a multi-particle string model is studied by CFD simulation, with a high-speed video camera verifying the validity of simulation. It shows that stagnant liquid in liquid pendulum and liquid pocket would cause obvious external mass transfer limitation at high Thiele moduli, yet the effects of liquid pocket are more serious than liquid pendulum. The effects of liquid velocity, particle diameter, and particle number on effectiveness factor are evaluated. The effectiveness factor belonging to single particle due to absence of liquid pocket is higher than that of a multi-particle string, while the three-particle string model is similar to the four-particle approach, which indicates simulation of effectiveness factor in a trickle bed can be approximated by a three-particle string.

Process and Energy Intensification of Glycerol Carbonate Production from Glycerol and Dimethyl Carbonate in the Presence of Eggshell-Derived CaO Heterogeneous Catalyst

The process and energy intensifications for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate (DMC) using an eggshell-derived CaO heterogeneous catalyst were investigated. The transesterification reaction between glycerol and DMC was typically limited by mass transfer because of the immiscible nature of the reactants. By varying the stirring speed, it was observed that the mass transfer limitation could be neglected at 800 rpm. The presence of the CaO solid catalyst made the mass transport-limited reaction process more prominent. Mass transfer intensification using a simple kitchen countertop blender as an alternative to overcome the external mass transfer limitation of a typical magnetic stirrer was demonstrated. A lower amount of the catalyst and a shorter reaction time were required to achieve 93% glycerol conversion or 91% GC yield, and the turnover frequency (TOF) increased almost 5 times from 1.5 to 7.2 min−1 when using a conventional magnetic stirrer and countertop blender, respectively. In addition, using a simple kitchen countertop blender with 7200 rpm, the reaction temperature of 60 °C could be reached within approximately 3 min without the need of a heating unit. This was the result of the self-frictional heat generated by the high-shear blender. This was considered to be heat transfer intensification, as heat was generated locally (in situ), offering a higher homogeneity distribution. Meanwhile, the trend toward energy intensification was promising as the yield efficiency increased from 0.064 to 2.391 g/kJ. A comparison among other process intensification techniques, e.g., microwave reactor, ultrasonic reactor, and reactive distillation was also rationalized.

Cr (III) Removal Capacity in Aqueous Solution in Relation to the Functional Groups Present in the Orange Peel (Citrus sinensis)

Bioremediation is a pollutant removal method that has had a great boom due to the diversity of agroindustrial waste that can be used for this purpose, and that has shown having great efficiency and profitability in the adsorption of heavy metals, such as Pb, Cu, and Co. Based on the above, the present work carried out kinetic and equilibrium studies of bioadsorption of Cr (III) using orange peel (OP) as adsorbent, previously treated with methanol, water, and a water–methanol mixture at different pH (0.91, 1.78 and 2.72), and at 30 °C, finding that the adsorption capacity at equilibrium increases with increasing pH, having a maximum of 55 mg g−1 at pH 2.72—under these conditions, lower adsorption energy was used to remove Cr (III). In addition, it was determined that there are no external mass transfer limitations. An isoelectric point analysis indicated that the adsorption is not carried out by electrostatic forces and a FTIR study of the functional groups of OP showed a decrease in the main functional groups (pectin, cellulose, and lignin, among others), which is directly related to the adsorption capacity of the bioadsorbent.

Influence of H2 availability in the catalytic reduction of nitrates in fixed bed reactors

The effect of H2 availability in the catalytic reduction of NO3− was studied through experimental tests and theoretical estimations of mass transfer regime for H2, CO2 and NO3−. The experiments were carried out in a fixed bed reactor packed with bimetallic 0.75% (w) Pd-Cu catalysts supported on granular activated carbon at 25 °C. External mass transfer limitations were only significant in the case of H2 and resulted in lower selectivity to NH4+, particularly in the low gas surface velocity range (0.09–0.019 cm/s). Low availability of H2, becoming the limiting reagent for the reaction, contributed to lower selectivity to NH4+ due to lower H:N ratio at the catalyst surface. Decreasing space–time also led to lower selectivity to NH4+, probably due to the neutralization of OH− by the available H+ at catalytic sites, thus controlling local pH and favoring N2 production. Reduction of selectivity to NH4+ was achieved with lower loss of activity and NO3− conversion when gas flow was decreased than when liquid flow was decreased. The results indicate that the design and operation of reactors for the catalytic reduction of NO3− should consider conditions leading to H2 transfer control in order to reduce selectivity to NH4+, even though this could be at the expense of reaction rate and NO3− conversion.

Prilezhaev epoxidation of oleic acid in the presence and absence of ultrasound irradiation

AbstractBACKGROUNDEpoxidation of double bonds in vegetable oils provide valuable green intermediates for the chemical industry. The epoxidation of oleic acid with hydrogen peroxide according to the Prilezhaev principle was studied experimentally in a multiphase laboratory‐scale batch reactor operated isothermally at 50 °C and atmospheric pressure. A solid cation exchanger (Amberlite IR‐120) was used as the solid catalyst to enhance the slow step in the Prilezhaev process: the in situ formation of the epoxidation agent, peracetic acid, from hydrogen peroxide and acetic acid. A rotating basket stirrer was used to suppress the external mass transfer limitations and to guarantee a turbulent random flow in the vicinity of the catalyst particles. Kinetic experiments demonstrated the catalytic effect of the cation exchanger. Several experiments were performed in the presence and absence of ultrasound irradiation at different amplitudes.RESULTSThe exposure of ultrasound irradiation on the multiphase reaction mixture impaired the conversion of the double bonds and the yield of the epoxide, compared to a reference experiment conducted under silent conditions. Catalyst characterization by scanning electron microscopy and the determination of the acid sites in recycled catalyst samples confirmed that the main reason for deactivation was leaching and/or neutralization of the sulfonic acid groups from the solid catalyst matrix.CONCLUSIONSThe application of ultrasound at different input powers resulted in lower reaction yields compared to the silent reference experiment. This observation was attributed to deactivation of the catalyst caused by leaching and/or neutralization of the sulfonic groups promoted by ultrasound exposure. © 2021 Society of Chemical Industry (SCI).