Tetrapropyl Ammonium Research Articles

Probing the influence of synthesized hierarchical ZSM-5 catalyst in ex-situ catalytic conversion of real-world plastic waste into aromatic rich liquid oil

Plastic waste management has become a vitally important environmental and economic concern for researchers and technologists worldwide. Currently, catalytic pyrolysis of plastic waste emerged as a promising plastic waste management technique, further aiding the full-scale development of an alternate innovation to convert plastic waste into fuel (liquid oil) energy. Lately, zeolites have been one of the most suitable and versatile catalysts in converting plastic waste into fuel grade hydrocarbons via catalytic pyrolysis. The present work exhibits an attempt to synthesize and study the performance of a hierarchical ZSM-5 in a fixed bed reactor to convert the real-world (LDPE, HDPE, PP and PS) plastic wastes into higher quality fuel grade liquid oil. The hierarchical ZSM-5 catalyst having both mesopores and micropores (dual porosity) in its framework is synthesized by using a single organic template i.e., 10 % tetra propylammonium hydroxide (TPAOH). The catalyst performance study displays remarkable selectivity and increase in the yield of the aromatic component in the liquid oil obtained from different plastic wastes. The results indicate that presence of hierarchical catalyst has exceptionally lowered the reaction temperature in the range of 400–430 °C and increased the liquid oil yield in comparison with that of the thermal pyrolysis. Also, the obtained liquid oils have comparable fuel properties with that of kerosene and diesel.

Hierarchical HZSM-5 catalysts enhancing monocyclic aromatics selectivity in co-pyrolysis of wheat straw and polyethylene mixture

The limitation in bio-oil quality hampers its further utilization in the fuel or chemical industry. This study employed a combination of tetra propylammonium hydroxide (TPAOH) and NaOH solutions for HZSM-5 desilication to enhance the yield of monocyclic aromatic hydrocarbons in the catalytic co-pyrolysis of wheat straw with polyethylene. Results revealed hierarchical HZSM-5, prepared with equal mole concentrations of NaOH and TPAOH, exhibited optimal catalytic performance. The bio-oil from this process had an aromatic content of 72 %, with monocyclic aromatic hydrocarbons (MAHs) constituting 56.26 %. Further optimization was achieved through iron modification of hierarchical HZSM-5. The addition of 0.5 % iron-modified hierarchical HZSM-5 increased the aromatic hydrocarbons to 80.57 %, with BTX compounds (benzene, toluene, and xylene) reaching a selectivity of 61.9 %. This approach reduced polycyclic aromatic hydrocarbons (PAHs), contributing to less coke formation, presenting a promising method for high-quality bio-oil.

Regulating the inner Helmholtz plane with an electrophilic cation additive enabled stacked stratiform growth for highly reversible Zn anodes

Achieving consecutive flattening and dendrite-free deposition for the zinc anodes is essential to avoid internal short circuits or premature failure in the Zn-ion hybrid supercapacitor (ZHSC), which largely depends on the crystal growth during the electrocrystallization process. Herein, the tetrapropyl ammonium bromide additive was employed to reconstruct the inner Helmholtz plane (IHP) structure for manipulating the Zn deposition behavior and stabilizing the interfacial electrochemistry. Joint experimental and theoretical results show that electrophilic quaternary ammonium cations (TPA+) provoke the linkage effect after the specifical adsorption at IHP of the Zn electrode, which includes the molecular/ion distribution regulation, electrostatic shielding effect, crystallographic optimization, and solid electrolyte interphase (SEI) layer formation. The adsorbed TPA+ cations at IHP expel SO42− anions, bringing a reconfiguration of the ion/molecule distribution, which leads to a relatively uniform Zn2+ions distribution at electrode/electrolyte interface and a sluggish electroreduction reaction kinetics. Meanwhile, the electrostatic shielding effect regulates the crystallographic energetic preference of Zn deposits and induces the stratiform Zn growth and dominant Zn (002) texture. Concomitantly, the partial interfacial adsorbed TPA+ cations were electrochemically reduced to form the inorganic-organic hybrid SEI layer to further enhance the corrosion resistance and stability of the Zn electrode. Consequently, TPA+ cations mediated electrolyte enables Zn||Zn cells to exhibit a reversible plating/stripping performance for more than 2800 h. Additionally, a long-term cycling life can be obtained in the Zn||activated carbon ZHSC with this electrolyte. The electrolyte mediation strategy to realize the complementary interface effect and crystalline optimization provides promising feasibility on highly reversible Zn anodes.

Dynamic insights of volumetric and viscometric exploration of Surfactant-QAs behavior in aqueous medium at varied temperatures; molecular docking and antimicrobial perspectives“

Using density (ρ), sound speed (u), viscosity (η), molecular docking and antimicrobial study analyses, this work examined the intermolecular interactions that occur between Quaternary ammonium salts (QAs) (0.005, 0.010, 0.015 molkg−1) and cationic surfactant CTAB (Cetyltrimethylammonium bromide) in aqueous solutions at 298.15 K to 313.15 K at an interval of 5 K. The Quaternary ammonium salts taken are: Tetraethylammonium bromide (TEAB), Tetra propylammonium bromide (TPAB), and Tetrabutylammonium bromide (TBAB). To comprehend and deduce the interactions, apparent molar volumes (Vϕ), apparent molar isentropic value (κS,ϕ), isentropic compressibility (κS), and acoustical parameters (Lf),(RA),(Z) and ([U]) values have been computed using the measured (ρ) and (u) data whereas relative viscosity (ηr) and viscous relaxation time (τ) values have been deduced from viscosity data. These parameters collectively provide a comprehensive understanding of the structural rearrangement of amphiphilic molecules at the interface and the relative contributions of hydrophobic and electrostatic interactions between the surfactant and aqueous solutions of QAs. Additionally, both molecular docking and antimicrobial investigations have also been performed; molecular docking facilitated the examination of interactions between ligands and proteins. Whereas, antimicrobial studies help to evaluate the impact of gram-negative bacteria (S. typhi, P. aeruginosa) and gram-positive bacteria (S. aureus, B. cereus) on CTAB in the presence of aqueous solutions containing TBAB.

Assembled pentasil nanosheet zeolites: Adjusting the sheet thickness through a simple and direct dual templating approach

A simple one-step synthesis method is demonstrated, enabling the thickness of assembled silicalite nanosheets to be tuned from 2 to 30 nm. The adjustement is achieved by mixing two common organic structure-directing agents (OSDAs): tetrapropylammonium (TPA) and tetrabutylammonium (TBA). During the hydrothermal synthesis, there is a preferential uptake of TPA, and the proportion of incorporated TBA can be deduced accordingly. The proportion of TBA, known to favour silicalite nanosheets, determines the nanosheets’ thickness and the morphological variations observed.

Regionally spatial framework Al distribution in MFI channels and its impact on the n-butane cracking reaction pathways

The regulation of the engineering regionally spatial framework aluminum (AlF) distribution in MFI channels has been considered as an effective way for the production of light olefins by targeted fluid catalytic cracking (TCO) technology. In this work, ZSM-5 zeolites with controlled AlF distributions are facilely synthesized by tuning the combinations of pentaerythritol (PET), tetrapropylammonium (TPA) and Na cations. The AlF atoms in the prepared HZ5-[PET + Na] and HZ5-[TPA] samples are enriched in the straight channels and intersection channels, respectively, which are favorable to the n-butane monomolecular reaction pathway, promoting the propylene production. Whereas the AlF atoms in the HZ5-[TPA + Na] sample are simultaneously distributed in both the straight and intersection channels, the n-butane molecules preferentially take place monomolecular reaction in the straight channels to generate carbonium ions (e.g., C2H5+, C3H7+ and C4H9+). Subsequently, all of them enter into the intersection channels to induce the occurrence of bimolecular reaction. Such a process is conducive to the formation of ethylene. These insights can help to clarify the catalytic behavior of regional framework acid sites in ZSM-5 channels and then provide an effective approach to design efficient TCO catalysts.

Using water structuring by ions to address pattern loading in wet HF-based oxide recess etch

In the FinFET fabrication flow, a gap fill oxide is used to fill the space between the Si fins that needs to be recessed to define the height of the fin trench. However, with the used flowable chemical vapor deposition (FCVD) oxide, the eth rate depends on fin spacing, a phenomenon called pattern loading. In this work, we used water structuring by dissolved ions to decrease the etch rate between fins and control pattern loading. We first showed, using ATR-FTIR (Attenuated Total Reflection – Fourier Transform Infra-Red), that structure making and breaking ions proposed by Marcus (2009) for bulk solutions, could be used to modulate water structuring in nanotrenches. Then, the Tetra-propyl Ammonium cation (TPA+) and the triply ionized Phosphoric acid anion (PO43−) were selected as structure making additives in HF 0.5%. Optimization of the etchant composition allowed to suppress pattern loading for a gap of 15 nm width using TPAH:HF mixtures, but not using HF:H3PO4 mixtures. The etch rate obtained with TPAH:HF at unity pattern loading and at room temperature was about 4.7 nm/min. It could be improved to about 7 nm/min by increasing the temperature. The inefficacy of the Phosphoric acid was ascribed to a pH effect, as the mono-ionized Phosphoric acid species formed in HF was classified as a borderline ion with little structuring capability by Marcus.

Characterization of Zeolite ZSM-5 Synthesized from Kaolin and TPABr Using X-Ray Diffraction and Infrared Spectroscopy

Kaolin with alumina and silica content is used as the main material in this research to study the synthesis of ZSM-5 zeolite. The hydrothermal process was carried out through different aging times, namely 12, 24 and 36 hours. Tetrapropyl ammonium bromide (TPABr) was used as a template for the Mobile Five-1 (MFI) structure guide. X-ray diffraction (XRD) and infrared spectroscopy (FTIR) instruments were used to characterize the ZSM-5 zeolite formed from the synthesis results. This was done to identify the phase change from kaolin to zeolite ZSM-5. The results of the analysis using XRD for all samples showed a characteristic peak of the ZSM-5 zeolite at 2θ around 7.88°; 8.72° ;23.09°; 23.84° and 24.32°. However, samples with an aging time of 12 hours also showed peaks at 2θ around 15.84° and 26.03° which indicated an analsim phase. The absorption bands from the FTIR characterization for all samples are seen at wave numbers around 453, 542, 793, 1088 and 1221 cm−1 which are the characteristic peak points of ZSM-5 zeolite. The longer the aging time indicates that the crystallinity of the ZSM-5 zeolite is increasing. The highest crystallinity was obtained from ZSM-5 zeolite samples which were aged for 36 hours. This indicates an increasing number of ZSM-5 crystal nuclei with high purity because there is no other phase besides the ZSM-5 phase.

Action at a distance: organic cation induced long range organization of interfacial water enhances hydrogen evolution and oxidation kinetics.

Engineering efficient electrode-electrolyte interfaces for the hydrogen evolution and oxidation reactions (HOR/HER) is central to the growing hydrogen economy. Existing descriptors for HOR/HER catalysts focused on species that could directly impact the immediate micro-environment of surface-mediated reactions, such as the binding energies of adsorbates. In this work, we demonstrate that bulky organic cations, such as tetrapropyl ammonium, are able to induce a long-range structure of interfacial water molecules and enhance the HOR/HER kinetics even though they are located outside the outer Helmholtz plane. Through a combination of electrokinetic analysis, molecular dynamics and in situ spectroscopic investigations, we propose that the structure-making ability of bulky hydrophobic cations promotes the formation of hydrogen-bonded water chains connecting the electrode surface to the bulk electrolyte. In alkaline electrolytes, the HOR/HER involve the activation of interfacial water by donating or abstracting protons. The structural diffusion mechanism of protons in aqueous electrolytes enables water molecules and cations located at a distance from the electrode to influence surface-mediated reactions. The findings reported in this work highlight the prospect of leveraging the nonlocal mechanism to enhance electrocatalytic performance.

ZSM-5 Catalysts for MTO: Effect and Optimization of the Tetrapropylammonium Hydroxide Concentration on Synthesis and Performance

Light olefin production from methanol using various zeolite catalysts has industrial and economic importance considering the growth of the petrochemical market. Zeolites are generally synthesized using various organic templates as structure-directing agents (SDAs). In this study, synthesis of a series of ZSM-5 zeolites was performed systematically using the microwave-assisted crystallization method, and these samples were analyzed in detail to understand the effect of the SDA concentration. Powder diffraction, N2 adsorption, scanning electron microscopy, ammonia adsorption desorption, and 27Al and 29Si NMR spectroscopies were used for the characterization. The organic SDA tetrapropyl ammonium hydroxide (TPAOH/SiO2 mole ratio = 0.0500) is found to have an optimum concentration against the silica precursor for achieving the highest crystallinity, suitable morphology, ideal pore size, effective pore volume, and tuned microporous/mesoporous area. For samples with a template concentration ratio of 0.050 or higher, 29Si and 27Al NMR data revealed the presence of an intact ZSM-5 structure. Using a fixed bed reactor at 500 °C and atmospheric pressure, the catalytic performance of the selected catalysts from the series is investigated for the methanol-to-olefin conversion reaction. The sample with the highest crystallinity showed the best conversion, selectivity toward light olefins, and time on stream stability. It is also worth noting that the highest crystallinity, micropore area, and micropore volume are reached for the optimum value rather than the highest template concentration. This allows for a reduction in the template concentration and a move closer to a synthesis pathway benign to environment and economics.

Varied Morphological Study of Albite Nanomaterials at Low Temperature with Co-effect of Single Walled Nanotubes and Graphene Oxide for Kevlar Fabric Strength

A comprehensive study of synthesizing zeolite nanoparticles, with the addition of organic template, by reflux method has been chalked out to form crystals. The method is effectivly for the synthesis of zeolite nanocrystals, incorporating alkali metals, silica and organic template. The organic templates tetra-propyl ammonium hydroxide (TPAOH), tetra-propyl ammonium bromide (TPABr) or (TPABr, N,N,N-tripropyl-1-propanaminiumbromide), tetraethyl orthosilicate (TEOS) were added to assist the formation of zeolite (Albite) crystals. A cross linker tetraethyl orthosilicate (TEOS) was also mixed. Addition of carbon nanotubes (CNTs) and graphene oxide (GO) resulted into a unique nano morphology of Albite (when the time of reaction was less than 240 h). Effect of additives on morphology, particle size, crystal geometry, surface area, and particle shapes was characterized with FT-IR, X-ray diffraction, BET, EDX and SEM. For the practical point of view, Kevlar supported polymer membrane with the Zeolite as catalyst is used. Results show that polymeric supported fabric and catalyst supported fabric have same result with response to mechanical testing. This suggest that the Kevlar supported polymer membrane has potential application in industrial cables, asbestos replacement brake lining, under water applications, tyres, and body armors.

An efficient green protocol for the synthesis of 1,2,4,5-tetrasubstituted imidazoles in the presence of ZSM-11 zeolite as a reusable catalyst.

In this study, we have synthesized a series of ZSM-11 zeolite catalysts using tetrapropyl ammonium hydroxide as a structure-directing agent through a highly efficient hydrothermal method. The series of catalysts were studied by different techniques such as FT-IR spectroscopy, XRD, FE-SEM, HR-TEM, EDS, pyridine-FT-IR spectroscopy, and BET analysis. We focused on varying reaction time intervals from 18 to 48 hours to investigate the effect on catalytic activities of the synthesized series of catalysts. The percentages of aluminum increased in the framework of zeolites with increasing crystallinity, surface area, external surface area, and acidity in the series of ZSM-11 zeolites by increasing the time from 18 to 48 h. Then, we studied the catalytic activity of a series of ZSM-11 zeolites and found that the ZSM-11 zeolite (48 h) possesses higher catalytic activity towards the synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions. The present protocol scored well with excellent yield, short reaction time, clean reaction profiles, low catalyst loading, and no tedious workup. The catalyst (ZSM-11 zeolite 48 h) was recycled and reused in five runs without any considerable loss of activity and product yield.

Effect of Tetrapropyl Ammonium Hydroxide on Zn Dendrite Formation for Rechargeable Aqueous Battery

Rechargeable aqueous zinc-ion batteries (AZIB) have captured enormous attention due to their high safety nature, low cost, and environmental friendliness [1]. Recently, improving the performance of AZIBs by optimizing the anode is becoming more promising at the present research area. [2]. Based on current studies, it can be said that, zinc anode suffers from the dendrite formation on the surface during cycling leading to a poor cyclability of a battery and its termination due to short circuit [3]. It is very necessary to study the reasons for dendrite growth and provide an inhibition ways. Herein we report the effect of TPAH (tetrapropyl ammonium hydroxide) as electrolyte additive to suppress dendrite growth in mild acid aqueous electrolyte. All tests were performed in Zn //ZnCi2+LiCl//LiFePO4 system with and without additive. As the result, with the addition of TPAH an enhanced cyclability in consequence with a prolonged cycle life of Zn/LiFePO4 system were observed. The mechanism of TPAH interaction with electrolyte and Zn anode characterization before and after cycling is proposed based on the results of SEM, FTIR and XRD analysis. Acknowledgment This research was supported by the Grant (OPFE2021001 "New materials and devices for defense and aerospace applications") from the Ministry of Digital Development, Innovation and Aerospace Industry of the Republic of Kazakhstan.

Effect of the potassium iodide in tetrapropyl ammonium iodide-polyvinyl alcohol based gel polymer electrolyte for dye-sensitized solar cells

Low ionic conductivity in gel polymer electrolytes with large cations is undoubtedly a critical issue. This research’s main objective was to explore potassium iodide influences on the conductivity in gel polymer electrolytes. PVA-based gel polymer electrolytes (GPEs), including tetrapropyl ammonium iodide and potassium iodide have been prepared. The GPEs have been characterized by X-ray diffraction (XRD) and electrical impedance spectroscopy (EIS). The GPEs prepared haves been recognized as an amorphous region through the X-ray diffraction analysis. The GPE sample’s conductivity (100 wt% of tetrapropyl ammonium iodide) of 6.24 × 10−3 S cm−1 was the lowest. The existence of potassium iodide in the GPE system improves the conductivity. The conductivity of 9.72 × 10−3 S cm−1 of GPE containing 30 wt% of tetrapropyl ammonium iodide and 70 wt% of potassium iodide was the highest derived from the EIS analysis. All prepared GPEs have the potential to be used for dye-sensitized solar cell applications. The dye-sensitized solar cell efficiency has been improved by ~30% if potassium iodide exists in the GPE system.

Dual-template synthesis of hierarchically layered titanosilicate-1 zeolites for catalytic epoxidation of cyclooctene

A one-pot facile route for preparing hierarchically layered titanosilicate-1 (LTS-1) zeolites with stable interlayered mesopores was proposed by integrated using bolaform surfactant (BC ph-12-6-6 ) and tetrapropyl ammonium hydroxide (TPAOH) as dual templates. By tuning the molar ratios of BC ph-12-6-6 /TPAOH from 5/0 to 5/9, the corresponding LTS-1 samples showed continuous transformations in morphology and intensified degrees of intergrowth by TS-1 nanosheets, resulting in an effective interlayer self-pillaring to avoid the excessive collapse after the removal of the occupied templates by calcination. Moreover, the LTS-1 samples by dual-template synthesis manifested enriched contents of mononuclear octahedrally coordinated Ti species (“TiO 6 ”). Benefitted by the highly patulous structure and more accessible Ti active sites predominated with high-performance “TiO 6 ” species, the LTS-1 catalysts by dual-template synthesis exhibited a superior catalytic activity in the epoxidation of cyclooctene compared with the layered TS-1 directed by sole template of BC ph-12-6-6 and the conventional bulk TS-1. It is reasonable to expect that the demonstrated work has important implications for the design and facile synthesis of layered titanosilicate zeolite catalysts with a stably hierarchical structure and tunable catalytic oxidation activities by an optimized distribution of titanium coordination states containing the coordinated “TiO 4 ” and “TiO 6 ” species. • One-pot dual-template synthesis of hierarchically layered titanosilicate-1 (LTS-1). • Effective interlayer self-pillaring by integrated templating of BC ph-12-6-6 and TPAOH. • LTS-1 manifests enriched contents of mononuclear octahedrally coordinated Ti species (“TiO 6 ”). • Improved catalytic epoxidation performances by the highly patulous structure and more accessible Ti active sites.

A Multi-Nuclear MAS-NMR Study on the Structural Properties of Silicalite-1 Zeolite Synthesized Using N- and P-Based Organic Structure Directing Agents

The nature of organic structure directing agents (OSDAs) is of paramount importance in the final properties of zeolites, particularly the framework and porosity. Recently, the use of P-containing OSDAs has been employed for new zeolites, but there is little discussion compared to their analogues N-OSDAs. The main objective of this work is the characterization of pure silica MFI zeolite (silicalite-1) prepared by the dual-template route with tetrapropylammonium (TPA), tetrapropylphosphonium (TPP) cations, and mixtures thereof aiming to understand by advanced NMR methods how the nature of the organic influences the physico-chemical properties of the zeolite. Silicalite-1 has been successfully synthesized using the dual-template procedure with TPA and TPP molecules. Both OSDAs are incorporated into the zeolite without any specific preference, differently to that observed before for the TEA/TEP system, and homogenously mixed inside of the zeolite voids. The presence of TPP leads to the incorporation of less F, raising the concentration of Q3-defective sites in the silicalite-1 zeolites. Detailed NMR results indicate that those structural defects are close to the –CH3 group of the entrapped OSDAs in the zeolite and these defects consist of at least two silanol groups stabilizing the Si-O- species, which is responsible for the charge balancing.

Preparation and characterization of some new complex salts of Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions with tetra propyl ammonium iodide

New series of trivalent and divalent metal complex salts with general formula [R]n[M Cl nIn], where R=Tetra propylammonium iodide, M=Cr3+, Fe3+, Mn2+, Co2+, Ni2+, Cu2+ and Zn2+, n=2 or 3 were prepared and characterized by elemental analysis molar conductance, IR, UV/Visible spectra studies and magnetic measurements. These studies, were revealed on octahedral geometry around Cr3+ and Fe3+ metal ions and tetrahedral geometry around divalent metal ions.

Evaluation of Na-13X zeolites activity in the catalytic pyrolysis of rapeseed oil cake to produce bio-oil

Zeolite with cavities (Na-13XCAV) was obtained by treating of a commercially Na-13X zeolite with tetrapropyl ammonium hydroxide aqueous solution (TPAOH, 0.3 mol/L). In addition, to generate secondary mesopores in the zeolite network (Na-13XCAV-SM), the Na-13X zeolite was treated with a mixture solution of TPAOH/NaOH (ratio 1:1). The charaterization of the zeolites was performed by N2 sorption, X-ray diffraction spectroscopy and scanning electron microscopy. Na-13XCAV-SM showed a higher selectivity and was effective for increasing the hydrocarbon content in bio-oil, it was obtained a hydrocarbon yield of 6.8 wt %, which was over three times bigger than that resulted with Na-13 × . The properties of bio-oil produced were determined and a comparison of the properties depending on the catalyst used was made. In the presence of secondary mesopores,the diffusion of intermediates compounds became faster and their re-polymerization reactions were slowed down, thus, the resulting amount of coke was reduced and bio-oil fraction increased.

Tungsten-substituted Silicalite-1 with an interconnected hollow structure for catalytic epoxidation of cyclohexene

Abstract A novel hierarchical tungsten-substituted Silicalite-1 zeolite with the highly interconnected hollow structure (HWS-1) was synthesized for the first time by post-treating the purely microporous tungsten-substituted Silicalite-1 (WS-1) through simultaneous desilication and tungstation, in which a combination of sodium hydroxide and tetrapropyl ammonium hydroxide (TPAOH) was used to achieve a systematic balance between dissolution and recrystallization and further promote the synchronous tungstation with using sodium tungstate dihydrate as a tungsten source. Under an optimum addition ratio of NaOH/TPAOH, the resulted HWS-1 exhibited not only well retained microporosity and crystallinity but also obviously enlarged external surface area and mesopore volume in contrast to the parent WS-1. Furthermore, the effective tungstation also facilitated the substitution and increased the amount of coordinated W species in zeolite frameworks. The catalytic performance of HWS-1 was evaluated by the epoxidation of cyclohexene with using H2O2 as oxidant. Benefited by the highly interconnected hollow structure and more accessible active sites on the enlarged external surface, the HWS-1 catalyst revealed a higher catalytic activity with improved cyclohexene conversion than WS-1. Moreover, it was found that a significant positive effect on promoting epoxidation was achieved by tungsten-substituted Silicalite-1 (WS-1 and HWS-1) catalysts reflecting at a much higher selectivity of epoxide (>79%) in comparison with titanium-substituted Silicalite-1 (TS-1) (~50% selectivity of epoxide), due to their superior hydrophobicity and suitably weaker acidity, which further demonstrated the potential application of the developed hierarchical tungsten-substituted Silicalite-1 as a candidate catalyst for epoxidation and other selective oxidation reactions.

The effect of structure directing agents on micro/mesopore structures of aluminosilicates from Indonesian kaolin as deoxygenation catalysts

Abstract Indonesian kaolin was successfully transformed into aluminosilicates (ALS) via two-step hydrothermal synthesis using different structure directing agents (SDA). The effects of structure, porosity and catalytic activity of ALS were determined for deoxygenation of bio-oil into green diesel. The first hydrothermal step used silicalite and tetrapropyl ammonium hydroxide (TPAOH) as SDA, followed by the addition of cetyltrimethyl ammonium bromide (CTAB) in the second hydrothermal step to induce mesopores. Silicalite formed ZSM-5 with hierarchical structures meanwhile TPAOH produced ZSM-5 mainly with microporosity. ZSM-5 framework was rapidly formed when using TPAOH preventing the formation of mesostructure in the second crystallization processes. In the absence of SDA, the aluminosilicate was characterized as mesoporous Al-MCM-41. At similar Si/Al ratios, Al-MCM-41 exhibited high surface area, mesopore volume and surface acidities than ZSM-5, consequently enhancing the conversion and selectivity of deoxygenation reaction towards long-chain (C11-C18) green diesel hydrocarbon.