Diffusion Of Large Molecules Research Articles

Molecules as Lubricants at the Nanoscale:Tunable Growth of Organic Structures from Nano- to Millimeter-Scale Using Solvent Vapour Annealing.

The creation of ordered structures of molecules assembled from solution onto a substrate is a fundamental technological necessity across various disciplines, spanning from crystallography to organic electronics. However, achieving macroscopic order poses significant challenges, since the process of deposition is inherently impacted by factors like solvent evaporation and dewetting flows, which hinder the formation of well-organized structures. Traditional methods like drop casting or spin coating encounter limitations due to the rapid kinetics of solvent evaporation, leading to limited control over final uniformity and order. In response to these challenges, Solvent Vapour Annealing (SVA) has emerged as a promising solution for realizing ordered molecular structures at scales ranging from nano- to milli- meters. SVA decouples the self-assembly stage from the deposition stage by utilizing solvent vapours which can enable rearrangement, movement, and diffusion of large molecules on the surface even on a macroscopic scale. Essentially acting as "molecular lubricants," solvent vapours enable the formation of well-ordered molecular films. This review discusses the advancements, obstacles, and promising strategies associated with utilizing SVA for the development of innovative nanostructured thin films, and emphasizes the originality and effectiveness of molecular assembly on substrates achieved through this approach.

Hanging aqueous polyelectrolyte “Dropbags” at liquid surface for Bio-inspired systems

Water surfaces serve as habitats for numerous creatures and have inspired a wide range of innovations. Herein, we demonstrate the fabrication of bag-shaped hanging droplets (dropbags) at the liquid surface using miscible polyelectrolyte aqueous solutions. The surface tension at the liquid-liquid interface maintains the top-opening structure of the dropbag, and the coacervate layer, formed rapidly by electrostatic interactions, inhibits the diffusion of large molecules, providing the dropbag with a flexible shape. Particularly, the "scattered dropbags-in-dropbag" (SDID) system was employed to accelerate the hatching of brine shrimp, such diverse compartmentalized structures and biophilic materials have the potential to be used for the cultivation and research of various creatures.

Hydrodepolymerization of lignin with Ni supported on active carbon catalysts reduced at different temperatures

Various Ni supported on active carbon (Ni/AC) catalysts were acquired by reduced at different temperatures, among which Ni/AC-500 possesses the smallest particle sizes of metallic Ni species, favoring to more active sites exposed on the catalyst surface, and the suitable content of metallic Ni0, implying the high hydrogenolysis activity obtained. Additionally, the highest mesoporous volume of Ni/AC-500 promotes the diffusion of large molecules from lignin depolymerization. Therefore, Ni/AC-500 exhibits the higher lignin conversion and yields of liquid bio-oil and monomers, but the lower yield of bio-char in lignin hydrodepolymerization due to its higher hydrogenolysis activity compared with other catalysts.

In-Silico Modelling of Transdermal Delivery of Macromolecule Drugs Assisted by a Skin Stretching Hypobaric Device

ObjectivesTo develop a simulation model to explore the interplay between mechanical stretch and diffusion of large molecules into the skin under locally applied hypobaric pressure, a novel penetration enhancement method.MethodsFinite element method was used to model the skin mechanical deformation and molecular diffusion processes, with validation against in-vitro transdermal permeation experiments. Simulations and experimental data were used together to investigate the transdermal permeation of large molecules under local hypobaric pressure.ResultsMechanical simulations resulted in skin stretching and thinning (20%–26% hair follicle diameter increase, and 21%–27% skin thickness reduction). Concentration of dextrans in the stratum corneum was below detection limit with and without hypobaric pressure. Concentrations in viable epidermis and dermis were not affected by hypobaric pressure (approximately 2 μg bullet cm−2). Permeation into the receptor fluid was substantially enhanced from below the detection limit at atmospheric pressure to up to 6 μg bullet cm−2 under hypobaric pressure. The in-silico simulations compared satisfactorily with the experimental results at atmospheric conditions. Under hypobaric pressure, satisfactory comparison was attained when the diffusion coefficients of dextrans in the skin layers were increased from sim 10 μm2bullet s−1 to between 200–500 μm2bullet s−1.ConclusionsApplication of hypobaric pressure induces skin mechanical stretching and enlarges the hair follicle. This enlargement alone cannot satisfactorily explain the increased transdermal permeation into the receptor fluid under hypobaric pressure. The results from the in-silico simulations suggest that the application of hypobaric pressure increases diffusion in the skin, which leads to improved overall transdermal permeation.

Microwave-responsive SiC foam@zeolite core-shell structured catalyst for catalytic pyrolysis of plastics

Catalytic pyrolysis is a promising chemical recycling technology to supplement mechanical recycling since plastics can be broken down into monomers or converted to the required fuels and chemicals. In this study, a microwave (MW) -responsive SiC foam@zeoltie core-shell structured catalyst was proposed for the catalytic pyrolysis of polyolefins. Under microwave irradiation, the SiC foam core works as both microwave adsorber and catalyst support, thus concentrating the generated heat energy on the ZSM-5 zeolite shell, where the catalytic reaction takes place. SiC foam with an open cellular structure can also improve the global transport of mass and heat during plastics pyrolysis. In this work, the effects of the SiO2/Al2O3 ratio and alkaline treatment of ZSM-5 zeolite coated SiC foam under MW irradiation on the variations in product distribution from low-density polyethylene (LDPE) pyrolysis were investigated at 450 °C. The results indicated that the appropriate acidity and pore structure were crucial to upgrading gas and liquid products. Particularly, the creation of a mesoporous structure in ZSM-5 zeolite via alkaline treatment could improve the diffusion of large molecules and products, thus significantly increasing the selectivity of high-valued light olefins and aromatics while inhibiting the formation of unwanted alkanes, which are expected in the chemical industry. Concretely, the concentration of olefins in gas increased to 51.0 vol% for ZSM-5(50)-0.25AT, and 65.6 vol% for ZSM-5 (50)-0.50AT, compared with 45.2 vol% for the parent ZSM-5(50). The relative concentration of aromatics in liquid decreased from 96.6% for ZSM-5(50) to 75.9% for ZSM-5(50)-0.25AT, and 71.1% for ZSM-5(50)-0.50AT. Given the respective yield of gas and liquid, the total selectivity of C2–C4 olefins and aromatics for mesoporous ZSM-5 zeolites could reach 58.6–64.9% during LDPE pyrolysis, which were higher than that for the parent ZSM-5 zeolite.

The mechanism of light gas transport through configurational free volume in glassy polymers

A possible mechanism of small molecule transport in glassy polymer membranes containing configurational free volume (i.e., triptycene moieties) is proposed. To this aim, a family of triptycene-containing polybenzoxazoles (TPBOs) exhibiting systematically varied molar amount of triptycene units, ranging from 25% to 100%, was selected to perform a light gas (N2, CH4 and CO2) fundamental sorption-transport study. The dual mode sorption-mobility model was used to isolate the effect of configurational free volume on penetrant transport. CO2 and CH4 Henry's and Langmuir's mode diffusion coefficients were estimated and used to quantify the Henry's and Langmuir's contributions to CO2/CH4 diffusivity-selectivity as a function of the triptycene molar content in TPBOs. Interestingly, while the Henry's CO2/CH4 diffusivity-selectivity changes little with increasing amount of configurational free volume, the Langmuir's CO2/CH4 diffusivity-selectivity increases up to infinity when the molar triptycene concentration in the polymer is 75% or higher, showing that the diffusion of larger molecules (i.e., CH4) is increasingly hindered relative to smaller molecules (i.e. CO2) diffusion when more configurational free volume is incorporated in the polymer. In sharp contrast, pure- and mixed-gas sorption, as well as solubility-selectivity, is essentially unaffected by the triptycene molar content. According with this physical picture, the analysis of isosteric heats of CO2 sorption indicates that TPBOs plasticization resistance is independent of triptycene content.

Bioinspired Approaches to Self-Assembly of Virus-like Particles: From Molecules to Materials.

When viewed through the lens of materials science, nature provides a vast library of hierarchically organized structures that serve as inspiration and raw materials for new synthetic materials. The structural organization of complex bioarchitectures with advanced functions arises from the association of building blocks and is strongly supported by ubiquitous mechanisms of self-assembly, where interactions among components result in spontaneous assembly into defined structures. Viruses are exemplary, where a capsid structure, often formed from the self-assembly of many individual protein subunits, serves as a vehicle for the transport and protection of the viral genome. Higher-order assemblies of viral particles are also found in nature with unexpected collective behaviors. When the infectious aspect of viruses is removed, the self-assembly of viral particles and their potential for hierarchical assembly become an inspiration for the design and construction of a new class of functional materials at a range of different length scales.Salmonella typhimurium bacteriophage P22 is a well-studied model for understanding viral self-assembly and the construction of virus-like particle (VLP)-based materials. The formation of cage-like P22 VLP structures results from scaffold protein (SP)-directed self-assembly of coat protein (CP) subunits into icosahedral capsids with encapsulation of SP inside the capsid. Employing the CP-SP interaction during self-assembly, the encapsulation of guest protein cargos inside P22 VLPs can be achieved with control over the composition and the number of guest cargos. The morphology of cargo-loaded VLPs can be altered, along with changes in both the physical properties of the capsid and the cargo-capsid interactions, by mimicking aspects of the infectious P22 viral maturation. The structure of the capsid differentiates the inside cavity from the outside environment and serves as a protecting layer for the encapsulated cargos. Pores in the capsid shell regulate molecular exchange between inside and outside, where small molecules can traverse the capsid freely while the diffusion of larger molecules is limited by the pores. The interior cavity of the P22 capsid can be packed with hundreds of copies of cargo proteins (especially enzymes), enforcing intermolecular proximity, making this an ideal model system in which to study enzymatic catalysis in crowded and confined environments. These aspects highlight the development of functional nanomaterials from individual P22 VLPs, through biomimetic design and self-assembly, resulting in fabrication of nanoreactors with controlled catalytic behaviors.Individual P22 VLPs have been used as building blocks for the self-assembly of higher-order structures. This relies on a balance between the intrinsic interparticle repulsion and a tunable interparticle attraction. The ordering of VLPs within three-dimensional assemblies is dependent on the balance between repulsive and attractive interactions: too strong an attraction results in kinetically trapped disordered structures, while decreasing the attraction can lead to more ordered arrays. These higher-order assemblies display collective behavior of high charge density beyond those of the individual VLPs.The development of synthetic nanomaterials based on P22 VLPs demonstrates how the potential for hierarchical self-assembly can be applied to other self-assembling capsid structures across multiple length scales toward future bioinspired functional materials.

Understanding the Diffusion Properties of Sulfur-Containing Compounds in Mesoporous Alumina: A Molecular Dynamics Study

Enhancing the diffusion of reactants in catalysts is imperatively needed in the hydrodesulfurization process. However, diffusion properties of sulfur-containing compounds are poorly characterized owing to experimental limitations. Herein, molecular dynamics (MD) simulation was applied to explore diffusion properties of thiane, thiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene in mesoporous alumina with pore sizes of 11.8, 13.6, and 15.3 nm. It is found that larger pore size and higher temperature facilitate diffusion. In other words, with the increase of pore size and temperature, the self-diffusion coefficient increased while the average interaction energy dropped. Notably, the diffusion activation energy showed that diffusion of larger molecules was more sensitive to variations in pore size and temperature. Furthermore, the effect of the molecular structure on diffusion was also studied; the increase in the number of benzene rings and branched chains was detrimental to diffusion. The simulated results were demonstrated by our experimental findings and harbor tremendous guiding significance for the design of effective hydrodesulfurization catalysts.

Diffusion of Protein Molecules through Microporous Nanofibrous Polyacrylonitrile Membranes.

Porous nanofibrous membranes have ultrahigh specific surface areas and could be broadly employed in protein purification, enzyme immobilization, and biosensors with enhanced selectivity, sensitivity, and efficiency. However, large biomolecules, such as proteins, have hindered diffusion behavior in the micro-porous media, significantly reducing the benefits provided by the nanofibrous membranes. The study of protein diffusion in polyacrylonitrile (PAN) nanofibrous membranes produced under varied humidity and polymer concentration of electrospinning revealed that heterogeneous structures of the nanofibrous membranes possess much smaller effective pore sizes than the measured pore sizes, which significantly affects the diffusion of large molecules through the system though sizes of proteins and pH conditions also have great impacts. Only when the measured membrane pore size is at least 1000 times higher than the protein size, the diffusion behavior of the protein is predictable in the system. The results provide insights into the design and applications of proper nanofibrous materials for improved applications in protein purification and immobilizations.

Probing the pore structure of hierarchical EU-1 zeolites by adsorption of large molecules and through catalytic reaction

The adsorption of toluene and 1,3,5-trimethylbenzene and the catalytic transformation of 1,3,5-trimethylbenzene are applied as probing approaches to characterize the pore system of hierarchical EU-1 zeolites prepared using organofunctionalized fumed silica as the silicon source. The adsorption and diffusion of toluene and 1,3,5-trimethylbenzene are significantly improved in the hierarchical EU-1 zeolites compared with the conventional microporous EU-1 zeolite. The adsorption kinetics of toluene and 1,3,5-trimethylbenzene suggested that introducing mesopores significantly increases the rate of adsorption and improved the diffusion of large molecules. In the catalytic transformation of 1,3,5-trimethylbenzene, the conversion of 1,3,5-trimethylbenzene on the hierarchical EU-1 zeolites is doubled compared with the conventional microporous EU-1 zeolite, due to the improved diffusion of bulky molecules and enhanced accessibility of active sites in the hierarchical EU-1 structure. Although isomerization is the main reaction, differences are observed in the product ratios of isomerization to disproportionation between the hierarchical EU-1 zeolites and the microporous counterpart with different times on stream. The transformation of 1,3,5-trimethylbenzene over the hierarchical EU-1 zeolites has a higher isomerization to disproportionation ratio than that over the microporous EU-1 zeolite; this is due to the increased mesoporosity.

A multi-scale model for diffusion of large molecules in steam-exploded wood

In this paper, multi-scale modeling was used to resolve diffusion in steam-exploded wood at tracheid scales including sub-micrometer features of bordered pits. Simulations were performed using the lattice Boltzmann method with high-resolution X-ray tomography image data as the input for the microstructure. The results show an effective method for utilizing a variable diffusion coefficient to implement two length scales. This circumvents the need to resolve the bordered pits in detail, which requires massive computing power. Instead, the effective diffusion coefficient for one bordered pit is used as input for this model. Results based on the present model are comparable to experimental data. This methodology can be extended to more structural features at the microscale of wood, such as latewood and the cell wall. Obtaining a map of different diffusion coefficients based on features and scale gives a better overall understanding of diffusion and the importance of mass transport with regard to the pretreatment of wood.

Texture evolution of mesoporous SAPO-34 via a hard-templating sono-hydrothermal method for biodiesel production: Influence of carbon materials on nanocatalyst design

To solve the challenges of diffusion of large molecules of oil into the SAPO-34 pores, secondary carbon and polymeric templates are used in sonohydrothermal synthesis method. Structure of the catalysts was estimated by BET, XRD, TPD, EDX, FESEM, HRTEM, and FTIR analyses. The best pore distribution was obtained for the catalyst synthesized by charcoal active, in which the conversion was 83 % for the esterification reaction of oleic acid. To increase the activity of this catalyst, 5% CeO2 was accommodated on it by sono-solvothermal method which resulted in 94 % conversion. Kinetic studies showed that for all synthesized catalysts, the degree of esterification reaction was of the first order and CeO2 loaded sample had the highest rate constant, equal to 0.0013 min−1. By increasing the pore radius and acidic strength of the catalyst, the reaction rate constant increases due to the overcoming the penetration of large oil molecules and increased acidic activity.

A Comprehensive Review of the Applications of Hierarchical Zeolite Nanosheets and Nanoparticle Assemblies in Light Olefin Production

Light olefins including ethylene, propylene and butylene are important building blocks in petrochemical industries to produce various chemicals such as polyethylene, polypropylene, ethylene oxide and cumene. Traditionally, light olefins are produced via a steam cracking process operated at an extremely high temperature. The catalytic conversion, in which zeolites have been widely used, is an alternative pathway using a lower temperature. However, conventional zeolites, composed of a pure microporous structure, restrict the diffusion of large molecules into the framework, resulting in coke formation and further side reactions. To overcome these problems, hierarchical zeolites composed of additional mesoporous and/or macroporous structures have been widely researched over the past decade. In this review, the recent development of hierarchical zeolite nanosheets and nanoparticle assemblies together with opening up their applications in various light olefin productions such as catalytic cracking, ethanol dehydration to ethylene, methanol to olefins (MTO) and other reactions will be presented.

Adsorption kinetics in removal of basic nitrogen-containing compounds from practical heavy oils by amorphous silica-alumina

The adsorption behavior of basic compounds in practical vacuum gas oil is quantitatively analyzed on amorphous silica-alumina with acid sites, mesopores and thermal stability. Time course of adsorption capacity was found to be controlled by kinetics but not by equilibrium. The rate of adsorption was found to have pseudo second-order but not pseudo first-order kinetics, indicating that the adsorption rate was mainly controlled by the diffusion of large molecules. The particle size did not influence the adsorption quantity at equilibrium, whereas the smaller particle size increased the adsorption rate. The adsorption quantity at equilibrium was influenced by the molecular structure of basic compound due to steric hinderance around the basic site, whereas the adsorption rate strongly depended on the molecular size, supporting that the adsorption rate was mainly controlled by the diffusion of compounds in the pores of amorphous silica-alumina. Comparison of solvents showed that the adsorption quantity at equilibrium was influenced by the polarity but not by the molecular size, while the adsorption rate strongly depended on both the polarity and molecular size. The reusability of adsorbent silica-alumina was demonstrated by the stable adsorption capacity and rate after calcination for the regeneration.

Development of mixed matrix ZIF-8/polyvinylidene fluoride membrane with improved performance in solvent resistant nanofiltration

In the present study, the incorporation of zeolitic imidazolate framework 8 (ZIF-8) as an inorganic additive in the matrix of polyvinylidene fluoride (PVDF) membranes was investigated. The ZIF-8/PVDF mixed matrix membranes were prepared with 5, 10. 15, 20, and 25 wt% ZIF-8 and characterized using SEM, EDX, and AFM analyses. The fabricated membranes then were utilized in solvent resistant nanofiltration (SRNF) process for removal of Rose Bengal (RB) from ethanol and isopropanol (IPA). The modified mixed matrix membranes (MMMs) containing 25 wt% of ZIF-8 represented a rejection of 99.5% for RB solution in the IPA, which is 15% more than the bare PVDF membrane. 4.1% flux reduction was observed for blended membranes with 25 wt% of ZIF-8 during filtration of RB solution in the IPA, whereas this reduction was 16.1% for the bare PVDF membrane. The results of swelling studies revealed that the ZIF-8 modified membranes had a lower swelling degree in both ethanol and IPA solvents compared with bare PVDF due to the reduced available space for the diffusion of large molecules.

Protein-Polymer Block Copolymer Thin Films for Highly Sensitive Detection of Small Proteins in Biological Fluids.

In nearly all biosensors, sensitivity is greatly reduced for measurements conducted in biological matrices due to nonspecific binding from off-target molecules. One method to overcome this issue is to design a sensor that enables selective size-based uptake of proteins. Herein, a protein-polymer conjugate thin-film biosensor is fabricated that self-assembles into lamellae containing alternating domains of protein and polymer. Analyte is captured in protein regions while polymer domains restrict diffusion of large molecules. Device sensitivity and size-based exclusion properties are probed using two analytes: streptavidin (SA, 52.8 kDa) and monomeric streptavidin (mSA2, 15.6 kDa). Tuning domain spacing by adjusting polymer molecular weight allows the design of films that relatively freely uptake mSA2 and largely restrict SA diffusion. Furthermore, when detecting the smaller mSA2, no reduction in the limit of detection (LOD) is observed when transitioning from detection in the buffer to detection in biological fluids. As a result, LOD measured in fluid samples is reduced by 2 orders of magnitude compared to a traditional surface-immobilized protein monolayer.

Lattice Boltzmann simulations of diffusion in steam-exploded wood

Diffusion of large molecules throughout the porous microstructure of wood pretreated with steam explosion was investigated by using the lattice Boltzmann method for simulations. Wood samples were investigated with high-resolution X-ray tomography to effectively reconstruct an accurate geometry of the structural changes that ensue after pretreatment. Samples of approximately 1 mm3 with voxel sizes from 0.5 to 1 μm were examined with X-ray imaging. These large volumes, relative to what reasonably can be simulated, were divided into sub-volumes and were further reconstructed into geometries suited for the LBM simulations. The transient development of the concentration was investigated, and the effective diffusion coefficient at steady state was computed. Diffusion rates were found to increase significantly in the transversal direction due to the steam explosion pretreatment. The increase was observed both in the time needed for solutes to diffuse throughout the pores and in the effective diffusion coefficient. A shorter diffusion pathway and a higher connectivity between pores were found for the pretreated samples, even though the porosity was similar and the pore size distribution narrower than the native sample. These results show that local mass transport depends not only on porosity but also, in a complex manner, on pore structure. Thus, a more detailed analysis of pore space structure using tomography data, in combination with simulations, enables a more general understanding of the diffusional process.

Biomimetic proteoglycans diffuse throughout articular cartilage and localize within the pericellular matrix.

Biomimetic proteoglycan (BPG) diffusion into articular cartilage has the potential to restore the lost proteoglycan content in osteoarthritic cartilage given these molecules mimic the structure and properties of natural proteoglycans. We examined the diffusion characteristics of BPGs through cartilage with the use of a custom-made in vitro cartilage diffusion model in both normal bovine and human osteoarthritic cartilage explants. BPGs were introduced into the cartilage through essentially one-dimensional diffusion using osteochondral plugs. The molecular diffusion was shown to be size and concentration dependent. Diffusion profiles were found over different diffusion time intervals and the profiles were fit to a nonlinear Fickian diffusion model. Steady state 011012-7diffusion coefficients for BPGs were found to be 4.01 and 3.53 μm2 /s for 180 and 1600 kDa BPGs, respectfully, and these values are similar to other large molecule diffusion in cartilage. In both bovine and osteoarthritic human cartilage, BPGs were found localized around the chondrocytes. BPG localization was examined by labeling collagen type VI and soaking 5 μm thick sections of cartilage with BPG solutions demonstrating that the BPGs diffused into the cartilage and preferentially localized alongside collagen type VI in the pericellular matrix.

Chromatographic study of the structural properties of mesoporous silica layers deposited on radially elongated pillars

We report on the ability to change the layer properties of porous layered radially elongated pillar (PLREP) array columns and its relevance to the separation efficiency. The adjustment of the preparation condition resulted in the formation of a 1.2-fold thicker layer than the layer produced in the preceding study. The mesoporosity of the layer was controlled by changing the hydrothermal treatment temperature from 105 °C to 80 °C. Chromatographic characterization was performed on a commercial nano-LC system using the octadecylsilylated PLREP columns having the aforementioned characteristics, i.e. (1) different layer thickness (df = 180–220 nm) and (2) different mesoporosity (dp = 7.6–11.2 nm, Pore volume (Vp) = 0.733‒0.838 cc/g and Surface area (SA) = 364‒611 m2/g). For isocratic separations of an alkylphenone mixture, the change in both the layer thickness and the mesoporosity caused no significant difference in the column efficiency, while the thicker layer and the reduction of mesopore size resulted in a 1.3-fold increase and a 1.4-fold increase in the retention capacity, respectively. Based on the result of the examination using scanning electron microscopy and argon physisorption technique, the formar enhancement was in agreement with the increase in the layer thickness, and the latter one was attributed to the larger surface area. When applying a column with 16.5 cm long to gradient separations, the combination of the thicker layer and the smaller mesopores provided the peak capacity of 365 for the alkylphenone mixture at a 180 min gradient, while the combination of the thinner layer and the larger mesopores provided the peak capacity of 315. For peptide separations, it appeared that the thicker layer was still favorable, however, the lager mesopores were more advantageous for MWs of larger than 1000, providing a conditional peak capacity of 245 for a commercially available peptide mixture because of less content of small pores which hinder the diffusion of large molecules in pores in the layer.

Impact of Chain Length on the Catalytic Performance in Hydroisomerization of n-Alkanes Over Commercial and Alkaline Treated *BEA Zeolites

The present paper highlights the influence of desilication of nanocrystal *BEA zeolites (CP811 and CP814E) by different alkaline treatments in presence of NaOH alone, NaOH + TPABr and NaOH + TBAOH, on the catalytic performance in the hydroisomerization reactions of n-alkanes (n-C10, n-C12 and n-C14). The well-balanced catalyst was reached after impregnation of 1.5 wt% of Pt, where the activity and isomers selectivity was seen to be the maximum, knowing that the Pt content effect was studied on the CP811 zeolite catalyst. All the other catalysts were after impregnated by approximately 1.5 wt% of Pt. The improvement of the textural properties by means of desilication was not always accounting for the influence of the catalytic performance of the catalysts, but rather it may be the bifunctional characteristics in charge. The impact of chain length was investigated on the catalysts to study if the presence of the inter- and intracrystalline mesopores would account for better diffusion of larger molecules as, n-C12 and n-C14. It was found on the majority of the catalysts that the activity was high whether the chain length was, but the isomers selectivity was decreasing with chain length except on one catalyst that possesses high textural and bifunctional characteristics. Among the three n-alkanes studied, n-C12 have marked the highest TOF values and lowest selectivity to isomers, a phenomenon attributed to the confinement effect that seems to increase the interaction of n-C12 molecules with the acidic sites of the zeolites, apparently causing their strength to be higher. This effect was pronounced more with n-C12 than the other two n-alkanes.