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Diffusional limitations associated with zeolite microporous systems can be overcome by developing hierarchical zeolites, i.e., materials with a micro- and mesoporous framework. In this work, Y and ZSM-5 zeolites were modified using a surfactant-mediated hydrothermal alkaline method, with NaOH and cetyltrimethylammonium bromide (CTAB). For Y zeolite, after a mild acidic pretreatment, the effect of the NaOH+CTAB treatment time was investigated. For ZSM-5 zeolite, different concentrations of the base and acid solutions were tested in the two-step pretreatment preceding the hydrothermal treatment. The properties of the materials were studied with different physical–chemical techniques. Hierarchical Y zeolites were characterized by 3.3–5 nm pores formed during the alkaline treatment through the structure reconstruction around the surfactant aggregates. The effectiveness of the NaOH+CTAB treatment was highly dependent on the duration. For intermediate treatment times (6–12 h), both smaller and larger mesopores were also obtained. Hierarchical ZSM-5 zeolites showed a disordered mesoporosity, mainly resulting from the pretreatment rather than from the subsequent hydrothermal treatment. High mesoporosity was obtained when the concentration of the pretreating base solution was sufficiently high and that of the acid one was not excessive. Hierarchical materials can be obtained for both zeolite structures, but the pretreatment and treatment conditions must be tailored to the starting zeolite and the desired type of mesoporosity. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the adverse effects of sulfur oxides (SOx) released during the combustion process on the environment, health and economy, oxidative deep desulfurization of diesel has become a hotspot all over the world. In this paper, HY@TiO2-x composite catalysts with different TiO2 contents were synthesised by liquid-phase deposition using HY zeolite as the parent material. The catalysts were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Ultraviolet–Visible Diffuse Reflectance (UV–vis), Raman Spectroscopy, Scanning Electron Microscopy (SEM), N2-physisorption, X-ray Photoelectron Spectroscopy (XPS). The characterization results of XRD, FT-IR, UV–vis and Raman showed that TiO2 was successfully loaded on HY zeolite. The catalysts were applied to the oxidative desulfurization (ODS) and adsorption desulfurization of benzothiophene (BT) and dibenzothiophene (DBT). Under the selected reaction condition: T = 70℃, n(H2O2)/n(Sulfur) = 6, moil: mcatalyst = 35: 1. The results show that the HY@TiO2-1.5 catalyst has the best oxidation activity, and the conversion rates of BT and DBT were 85.0% and 99.7%, respectively. Meanwhile, the adsorption of BT and DBT were 5.06 and 10.93 mg-S/g-Cat. respectively. HY@TiO2-1.5 catalyst is simple to prepare, with a high activity of bulky organic sulfides adsorption-oxidative desulfurization and has a potential application in oil refining. The reasons for the improvement of organic sulfide adsorption and oxidative desulfurization activity on HY @ TiO2-1.5 catalyst are discussed. [ABSTRACT FROM AUTHOR]

Middle-distillate hydrocracking nanoporous catalysts with good cracking activity and isomerization activity were prepared to improve the middle distillates such as kerosene and diesel quality and yield. Using a hydrothermal method, we synthesized nanoporous flower-like xY-SAPO-11 composite molecular sieves with different weight percentages. For comparison, Y + SAPO-11 mechanical mixture were also prepared by mechanical mixing. A series of characterization methods were used to characterize the composites and mechanical mixture. Hydrocracking catalysts Cat-xY-S and Cat-Y + S were prepared with composites and mechanical mixture as the support acidic components, respectively, and their catalytic performance in hydrocracking was investigated. It is demonstrated that nanoporous composite molecular sieves perform differently from mechanical mixture regarding physicochemical and catalytic properties. The Y-SAPO-11 composite molecular sieves have larger pore volumes and pore sizes and lower acidity than the mechanically mixed molecular sieves with the same weight percentage. This is caused by the interaction between the SAPO-11 and Y phases. This interaction leads to the SAPO-11 and Y phases being combined by chemical bonding, forming a coordination structure of the framework elements. The composite molecular sieves exhibited higher yields of C8–C12 products than mechanical mixtures in the hydrocracking reaction. When the Y-phase weight percentage was 61.7 wt %, i.e., the Cat-8Y-S catalyst with suitable cracking activity and isomerization activity, it had the highest isomerized C8–C12 product yield of 33.1% at 360 °C while maintaining a high C8–C12 product yield. [ABSTRACT FROM AUTHOR]

Diffusional limitations associated with zeolite microporous systems can be overcome by developing hierarchical zeolites, i.e., materials with a micro- and mesoporous framework. In this work, Y and ZSM-5 zeolites were modified using a surfactant-mediated hydrothermal alkaline method, with NaOH and cetyltrimethylammonium bromide (CTAB). For Y zeolite, after a mild acidic pretreatment, the effect of the NaOH+CTAB treatment time was investigated. For ZSM-5 zeolite, different concentrations of the base and acid solutions were tested in the two-step pretreatment preceding the hydrothermal treatment. The properties of the materials were studied with different physical–chemical techniques. Hierarchical Y zeolites were characterized by 3.3–5 nm pores formed during the alkaline treatment through the structure reconstruction around the surfactant aggregates. The effectiveness of the NaOH+CTAB treatment was highly dependent on the duration. For intermediate treatment times (6–12 h), both smaller and larger mesopores were also obtained. Hierarchical ZSM-5 zeolites showed a disordered mesoporosity, mainly resulting from the pretreatment rather than from the subsequent hydrothermal treatment. High mesoporosity was obtained when the concentration of the pretreating base solution was sufficiently high and that of the acid one was not excessive. Hierarchical materials can be obtained for both zeolite structures, but the pretreatment and treatment conditions must be tailored to the starting zeolite and the desired type of mesoporosity.

This article explores the degradation of glycerol to ethanol using different catalysts and the effect of sonication time on the reaction. The study found that the NiMo/YZ catalyst was the most effective in producing ethanol, and the longer the sonication time, the higher the yield of ethanol. The Y Zeolite was activated and impregnated with Ni and Mo metals to act as active catalyst sites. The article also mentions the potential for further research on metal leaching and the by-products of glycerol degradation. [Extracted from the article]

Nanofibers have attracted a lot of interest in the biomedical field. Researchers in biomedical field are highly interested in polyethersulfone/polyvinylpyrrolidone (PES/PVP)-zeolite hybrid composite nanofiber. This research study on the development of biocompatible hybrid nanofiber containing zeolite, nanofiber membranes based on polyestersulfone as the first component and polyvinylpyrrolidone loaded with zeolite as the second component were prepared using the double axials electrospinning method. 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide results and cell culture also showed that the PES/PVP-zeolite hybrid nanofiber scaffolds made in this study have excellent compatibility for the growth of L929 fibroblasts. Therefore, PES/PVP-zeolite hybrid nanofiber can provide biomedical applications. [ABSTRACT FROM AUTHOR]

Y-type zeolites are widely used in the carbon dioxide (CO2) adsorption applications due to their exceptional ion exchange performance and high stability. However, the pelletization of Y powder by adding binders such as kaolin often results in performance drops, which has limited its industrial application. This study employs a zeolite-kaolin blend to produce cylindrical pelletized Y zeolite, in which the kaolin is then transformed to zeolites via hydrothermal crystallization, resulting in binder-free Y pellets. The Design-Expert software and the response surface method (RSM) are employed to optimize the hydrothermal crystallization conditions for binder transformation, with the objective of attaining a maximized capacity for CO2 adsorption. Results demonstrate that optimized synthesis conditions yield cylindrical Y zeolite with a notable CO2 adsorption capacity of 5.52 mmol/g at 298 K and 1 bar, surpassing that of the initial Y powder. The average crushing strength is 110 N per particle (Diameter × Height = 3 mm × 3 mm). The IAST selectivity of CO2/N2 (15/85) is 824 at 298 K and 1 bar. The reaction mechanisms of the binder transformation are also investigated via experiments and DFT simulation. This study presents a simple and reliable method for manufacturing binder free Y zeolite, which is promising for carbon capture applications.

A sustainable defect‐engineering strategy for the dealumination of Y zeolite is described. This strategy includes the green synthesis of a well‐crystallized Y zeolite with point defects arising from the incorporation of Fe atoms by using Fe‐containing perlite and the subsequent preparation of ultra‐stable Y (USY) zeolite by efficient steaming dealumination. The systematic characterizations verify that Fe atoms originally existing in the perlite are incorporated into the as‐synthesized Y zeolite and function as point defects, leading to the distortion of framework Al. The step‐by‐step investigation of dealumination process shows that vacancies are formed by the extraction of framework Fe in ammonium exchange, and the framework dealumination is promoted under the combined effect of the distorted framework Al and the formed vacancies during steaming treatment. The resulting USY zeolite owns excellent features in (hydro)thermal stability, pore structure and acid property, and exhibits outstanding catalytic performance in the cracking of n‐octane and 1,3,5‐triisopropylbenzene. [ABSTRACT FROM AUTHOR]

The most important natural resource for human health and well-being is water, which can be affected by different sources, such as physical, organic, chemical, and microbiological ones. CBV 760 commercial zeolite was used and tested to remove inorganic pollutants, lead, and cadmium. Adsorption isotherms were used to assess the adsorption properties of contaminants and real effluent. At the solution pH (4.5 and 5), adsorption kinetics and isotherms were conducted for lead and cadmium, respectively. The investigated zeolite was quite efficient in lead and cadmium removal, as the maximal adsorbed amounts were Qa = 175 and 148 mg g−1 for lead and cadmium, respectively, at T = 308 K. Adsorption capacity is pH dependent. Adsorption of Pb2+ and Cd2+ is highest at pH 8 (Qa = 107 and 53.58 mg g−1, respectively). The CBV 760 displays more affinity for Pb2+ than Cd2+. It is worth noticing that CBV 760 exhibits good selectivity for heavy metal retention metals, namely, Ni2+, Cu2+, Cd2+, and Pb2+, in an actual contaminated effluent with a removal yield of 80% on CBV 760. [ABSTRACT FROM AUTHOR]

A set of Y-type zeolites with Si/Al atomic ratios between 7–45 were studied as catalysts in the aminocyclization reaction between acrolein and ammonia to produce pyridine and 3-picoline. The catalytic activity tests at 360 °C revealed that the acrolein conversion increased in the order Z45 < ZY34 < ZY7 < ZY17, in agreement with the increase of the total acidity per gram of catalyst. In all cases, pyridine bases and cracking products (acetaldehyde and formaldehyde) were detected in the outflow from the reactor. The total yield of pyridines was inversely proportional to the total acidity for the catalysts, which presented large surface areas and micro- and mesoporosity. The selectivity towards 3-picoline was favored when using catalysts with a Brønsted/Lewis acid sites ratio close to 1. The formation of pyridine occurred more selectively over Lewis acid sites than Brønsted acid sites. The deactivation tests showed that the time on stream of the catalysts depended on the textural properties of zeolites, i.e., large pore volume and large BET area, as evidenced by the deactivation rate constants and the characterization of the spent catalysts. The physicochemical properties of the catalysts were determined by XRD, UV-vis, and Raman spectroscopies, infrared spectroscopy with adsorbed pyridine, N2 physisorption, and SEM-EDXS. After the reaction, the spent catalysts were characterized by XRD, Raman spectroscopy, TGA, and SEM-EDXS, indicating that the uniform deposition of polyaromatic species on the catalyst surface and within the porous system resulted in the loss of activity. [ABSTRACT FROM AUTHOR]

In this study, a density functional theory method is employed to investigate the reaction mechanisms of dimethyl carbonate (DMC) formation, through oxidative carbonylation of methanol, on four types of Y zeolites doped with Cu+, Cu2+, Cu2O and CuO, respectively. A common chemical route is found for these zeolites and identified as, first, the adsorbed CH3OH is oxidized to CH3O species; subsequently, CO inserts into CH3O to CH3OCO, which reacts with CH3O to form DMC rapidly; and finally, the adsorbed DMC is released into the gas phase. The rate-limiting step on Cu2+Y zeolite is identified as oxidation of CH3OH to CH3O with activation barrier of 66.73 kJ·mol−1. While for Cu+Y, Cu2O-Y and CuO-Y zeolites, the rate-limiting step is insertion of CO into CH3O, and the corresponding activation barriers are 63.73, 60.01 and 104.64 kJ·mol−1, respectively. For Cu+Y, Cu2+Y and Cu2O-Y zeolites, adsorbed CH3OH is oxidized to CH3O with the presence of oxygen, whereas oxidation of CH3OH on CuO-Y is caused by the lattice oxygen of CuO. The order of catalytic activities of these four types of zeolites with different Cu states follows Cu+Y ≈ Cu2O-Y > Cu2+Y > CuO-Y zeolite. Therefore, CuY catalysts with Cu+ and Cu2O as dominated Cu species are beneficial to the formation of DMC. [ABSTRACT FROM AUTHOR]

In this study, zeolites (Z) were used as catalysts in the cracking of a Colombian vacuum gas oil (VGO), with a focus on product distribution and coke deposition. The catalytic tests were carried out in a MAT-type reactor under typical conditions. The zeolites were subjected to alkaline treatment with NaOH at concentrations ranging from 0.05 to 0.4 mol/L, resulting in the creation of several samples (Z-0.05, Z-0.10, Z-0.20, Z-0.30 and Z-0.40) that were then hydrothermally stabilized (Z-0.05-M, Z-0.10-M, Z-0.20-M, Z-0.30-M and Z-0.40-M) to increase mesoporosity and reduced crystallinity. The increase in mesoporosity was accompanied by an improvement in acidity. Despite Z-0.30-M having higher acidity, Z-0.00-M and Z-0.10-M exhibited the highest activity due to their high crystallinity and microporosity, yielding the highest gas yields. Gasoline was the main product, with maximum yields exceeding 30%. Z-0.20-M produced more aromatic and olefin compounds than the others, resulting in higher quality gasoline. Coke formation followed the trend: Z-0.00-M

In the hydrocracking of 9, 10-dihydroanthracene, acid sites and their locations in the Y zeolites play crucial roles. Hydrogen transfer is the dominant reaction for the industrial Y zeolites with undeveloped mesopores whether at low or high temperatures. Those with developed mesopores exhibit enhanced ring-opening and cracking ability due to the improved molecular transport and accessibility of acid sites. Their ring-opening and cracking ability is crucially related to the amount of highly strong Brønsted acid sites in the high-silica Y zeolites. The reaction processes of 9, 10-dihydroanthracene hydrocracking over the industrial Y zeolites with different properties were expounded rationally.

In order to further improve the hydrogenation performance of the existing hydrotreating (HDT) catalysts and explore the structure-activity relationship of the catalysts, a series of Ni modified Y zeolites were successfully synthesized by in-situ synthesis method, and the corresponding NiMo catalysts supported on Ni modified Y zeolites and γ-Al 2 O 3 were prepared for diesel fuel hydrotreating. The effect of Ni modification on the properties of the synthesized xNiY zeolites and the corresponding NiMo/AxNiY catalysts were determined by the characterization techniques such as XRD, ICP-AES, N 2 physical adsorption-desorption, SEM, UV-Vis DRS, Py-FTIR, HRTEM and XPS. The results show the in-situ modification method can achieve a favorable composite effect of Ni species and the Y zeolites and Ni modification can affect the physical-chemical properties of the synthesized Y zeolites and the NiMo/AxNiY catalysts in varying degrees. Although Ni modification led to a slight decrease in the specific surface areas and pore volumes of the Y zeolites, it can promote the particle uniformity and improve the number of acid sites of the Y zeolites, which are beneficial to the adsorption of sulfide molecules. Moreover, the incorporation of Ni into Y zeolites can also effectively improve the number of acid sites of the prepared NiMo/AxNiY catalysts and improve the stacking number of MoS 2 slabs, and enhance the Mo species dispersion, which promote the adsorption and hydrogenation performances of the reactants on the catalysts. Hence, the catalysts containing Ni modified Y zeolites exhibited higher hydrotreating activity compared with the catalyst containing unmodified Y zeolites. Among the four investigated catalysts, the NiMo/A3NiY was found to be the most favorable for the purpose of preparing highly active hydrotreating catalysts for diesel fuels. The incorporation of Ni into Y zeolite improves the utilization rate of active metals on the NiMo/AxNiY catalysts. [Display omitted] • Ni incorporated into Y zeolite was successfully synthesized by in-situ synthesis method. • Ni modification promotes the particle uniformity and improves the number of acid sites of the Y zeolite. • The incorporation of Ni into Y zeolite improves the stacking number of MoS 2 slabs and enhances the Mo species dispersion. • NiMo/A3NiY catalyst showed the best hydrogenation activity. [ABSTRACT FROM AUTHOR]

Y Zeolite plays an irreplaceable role in many important applications due to its unique physicochemical properties, which has attracted extensive attention from researchers. Response surface methodology (RSM) was used to optimize the process parameters for the hydrothermal synthesis of Y zeolite using kaolin activated by microwave heating. The best relative crystallinity was 108.17% could be achieved at the condition: the aging temperature of guiding agent was 65 ℃, the crystallization temperature was 100 ℃, the crystallization time was 24 h. In addition, the aging temperature of guiding agent was the most important influence factor. Under the optimal condition, the SiO2/Al2O3 ratio of synthesized Y zeolite was 4.54, 90% of the particle size was less than 60 μm, and the specific surface area of Y zeolite was 479 m2/g. The successful preparation of Y zeolite with high crystallinity is expected to provide reference for the application of wastewater treatment, CO2 sequestration and fluid catalytic cracking for petroleum. [ABSTRACT FROM AUTHOR]

The catalytic hydrogenation and hydrogenolysis activity run counter to each other under Ti modification. [Display omitted] • Ti species were able to exist in Y zeolites in tetracoordinated and six-coordinated forms. • The BAS/LAS value of the catalyst decreased with the increase of Ti content. • Ti doping promoted the formation of active phase with high hydrogenation activity. • Suitable BAS/LAS value and active phase stacking resulted in the highest catalytic activity. Ti modified Y zeolites with different Ti content were synthesized by in-situ hydrothermal crystallization method and used as the support of hydrodenitrogenation (HDN) catalyst. The forms of Ti species in the zeolites and the effect of Ti incorporation on the active metal states of the corresponding catalysts were investigated by XRD, UV–Vis DRS, XPS, HAADF-STEM, ICP-OES, Py-FTIR, H 2 -TPR, HRTEM, and DFT calculation. The results show that the incorporation of in-situ Ti species into Y zeolite led to a decrease in the Brønsted acid sites (BAS) /Lewis acid sites (LAS) value of the corresponding catalyst, but effectively enhanced the stacking layer number of the WS 2 active phase by weakening the interaction between the active metals and the supports, which is manifested in the improvement of the hydrogenolysis activity and the decrease of the hydrogenation activity of the catalyst. When the hydrogenolysis activity and hydrogenation activity in the catalyst match to a certain extent, that is, the BAS/LAS value and the stacking layer number of the active phase reach an appropriate value, the HDN catalyst exhibited the highest catalytic activity. The NiW/Y-0.1Ti catalyst with suitable amount of BAS and stacking layer number of active phase showed the maximum k HDN values (11.7 × 10-4 mol·g−1·h−1 and 3.9 × 10-4 mol·g−1·h−1) and TOF s (1.91 h−1 and 1.04 h−1) of quinoline and indole HDN. [ABSTRACT FROM AUTHOR]

• Catalytic upgrading of bio-oil was conducted over metal oxide-modified Y zeolite. • The upgraded bio-oil by Fe/Y, Mg/Y and Zn/Y was rich in aromatics and phenols. • Ni/Y catalyst exhibited good selectivity to phenol and cresol. Pyrolysis as one of the most utilizations of biomass has aroused the increasing attention, however, the key is to upgrade biomass pyrolysis volatiles and enrich the high-valued chemicals in bio-oil. In this paper, different metal oxide-modified Y zeolites, including Fe/Y, Co/Y, Ni/Y, Mg/Y and Zn/Y, were prepared by wet impregnation and employed in catalytic upgrading of pyrolytic volatiles from rice straw (RS) and poplar sawdust (PS). Results showed that the modification by metal oxides led to the decrease of surface area and the changes in the acidity of zeolites. Higher yields of gas and water were obtained over metal oxide-modified zeolites at the expense of the bio-oil yields. More strong acid sites of the Ni/Y and Zn/Y catalysts promoted the generation of H 2. Fe/Y catalyst showed good selectivity to aromatics in bio-oil owing to high mesoporous volume and strong deoxidization capacity. The highest aromatic hydrocarbons content (63.0%) was obtained over Fe/Y in RS bio-oil. The formation of phenol and cresol was promoted with increasing the ratio of Lewis/Brönsted acid. Under the action of Ni/Y with the highest Lewis/Brönsted ratio, the phenol content in bio-oil from RS and PS pyrolysis was enhanced to 11.8% and 25.3%, respectively. The Fe/Y catalyst had good upgrading performance during three reaction-regeneration cycles. In addition, the possible reaction mechanism of biomass pyrolysis volatiles over metal oxide-modified Y zeolites was proposed. This work will provide a guide for the composition regulation of bio-oil from biomass pyrolysis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is challenging to establish single metal atoms with a uniform coordination environment at targeted sites of a zeolite. In this study, single platinum atoms were selectively encaged in the six‐membered rings of sodalite (SOD) cages within Y zeolite using a template‐guiding strategy. During the in situ synthesis process, template molecules were designed to occupy supercages and thereby force coordinated platinum species into SOD cages. Subsequent control of the post‐treatment conditions yielded the Y zeolite with selectively encaged single platinum atoms, denoted Pt@Y‐SOD. The Pt@Y‐SOD catalyst had good stability and excellent catalytic selectivity in the semihydrogenation reaction, and it exhibited interesting thiophene and carbon monoxide resistance in this transformation because interactions with these poisons are weakened by the configuration of the encaged single platinum atoms. [ABSTRACT FROM AUTHOR]

A series of Y zeolites with different pore properties was prepared as a support for hydrocracking catalysts for the production of BTEX (benzene, toluene, ethyl-benzene, and xylene) from tetralin. Some important characterizations, including N2 adsorption–desorption, NH3-TPD, Py-IR, and HRTEM, were applied to obtain the properties of different catalysts. Meanwhile, the tetralin hydrocracking performances of those catalysts were investigated on a high-pressure fixed-bed microreactor. The results showed that Si/Al ratio is the core property of zeolites and that the increase in the Vmicro/Vmeso of zeolites could facilitate the formation of BTEX products by hydrocracking tetralin. The method of hydrocracking tetralin was proposed. It was also found that the hydrogenation–cracking path was controlled by aromatic saturation thermodynamics, and strong acidity aided the backward shift of equilibrium temperature. [ABSTRACT FROM AUTHOR]

Unsatisfactory performance and poor lifetime encountered by most catalysts severely confine their advancement in practical applications. Herein, the metallic oxide catalysts employing Y zeolite as support were prepared by the impregnation method to address these obstacles in catalytic oxidation of toluene with ozone. The results show that Cu-Mn/Y bimetallic catalyst (CM-Y) possesses relatively high toluene conversion and ozone decomposition efficiency at room temperature because of the high reduction ability and enhanced mobility of oxygen in comparison with those of the monometallic catalysts. Furthermore, the effects of the key operating parameters (O3/C7H8 volume ratio, moisture content, and reaction temperature) were investigated over the CM-Y catalyst. And the results suggest that the minimum O3/C7H8 volume ratio of 10 and reaction temperature of 100 ℃ were required to obtain high catalytic activity and steady-state ozonation of toluene. The splendid toluene conversion of ~ 97.5% and COx selectivity of ~ 98.5% could be achieved under the optimal reaction conditions after the 500 h toluene oxidation reaction. Moreover, only < 0.04 ppm ozone could be detected in the outlet gas. Aforementioned results were also reasonably verified by various characterizations including H2-temperature-programmed reduction (H2-TPR), gas chromatography-mass spectrometer (GC–MS), and Fourier transform infrared (FT-IR) spectroscopy. CM-Y catalyst reveals a promising application prospect in ozone-assisted catalytic oxidation for VOC removal at low temperatures. [ABSTRACT FROM AUTHOR]

Coke formation on n-butene cracking catalyst is the main reason for the reducing of its lifetime. To study the effects of acidity and textural properties on the coke formation process, a series of HY zeolite-type catalysts were prepared by ammonium hexafluorosilicate treatment (AHFS). NH3-TPD and Py-IR-TPD were used to systematically study the change law of zeolite acidity. It was found that with the increase of AHFS concentration, the acid density decreased, whereas the ratio of Brønsted acid to Lewis acid first increased and then decreased. Meanwhile, the percentage of Brønsted acid inside the supper cages increased and the strength of Brønsted acid increased with the degree of dealumination. Combined with in situ IR study on coke formation, the relationship between coking and acid site was revealed. It was found that the rate of coke formation on zeolites was affected by acid density, which is the rate of coke formation decreased with the decline of acid density. When the acid density remains at the same level, it was the acid strength that determined the coke formation rate—the stronger the acid strength, the faster the coke formation rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heat treatment and ligand size adjustment could regulate Cu location in Y zeolite. • More copper could be located in supercages, resulting in more absorbed thiophene. • The Cu 10.74 Y 350 sample exhibits excellent desulfurization performance. Y zeolites modified with Cu are promising sorbents for adsorption desulfurization due to their cost-effectiveness. Only the supercage, which is larger than thiophene molecule, is the potential location of active sites for thiophene removal. However, numerous copper species cannot serve as effective active sites due to their inability to be located in the supercages. Based on this consideration, two strategies to regulate Cu location in Y zeolite to address the aforementioned challenges were explored. One is to adjust the molecular size of copper-ammonia ligands through pH value of cuprammonia solution, and the other is to prevent the migration of copper to small cages by heat treatment. The results showed that these two strategies could effectively regulate the location of copper active sites in Y zeolite. During heat treatment, Cu could transfer into supercages from sodalite cages at 350 °C. More effective copper would be targeted to be located in the supercages in the process of adjusting pH. For the best Cu 10.74 Y 350 sorbent, which was prepared at 350 °C under pH of 10.74, the Cu content in the supercages was the highest (25 %), and thus it has an excellent desulfurization efficiency of 82.3 %. [ABSTRACT FROM AUTHOR]

With a motivation of improving accessibility for mass transport of sterically bulky molecules, we demonstrate the synthesis of mesoporous Y zeolite catalysts with increased pore size. Our supramolecular approach relies on the swelling of surfactant assemblies with organic molecules, such as 1,3,5-trimethylbenzene (TMB), para -xylene (p -xylene), and 1,4-diisopropylbenzene (DIPB), as well as cosolvents consisting of ethanol and tert -butyl alcohol (TBA). With both trimethylalkylammonium bromide (C n TAB, n = 16 and 18) surfactants investigated, TMB exhibits a stronger swelling effect compared with both p -xylene and DIPB, which suggests an optimum in the hydrophobicity of the swelling agent. Cosolvents such as TBA and ethanol act as pore-size and porosity property modulators, with TBA exhibiting a greater degree of mesopore expansion than ethanol. Our optimized material consisted of a mesopore size of 6.8 nm and a mesopore volume of 0.41 cm3/g, which was synthesized with a TMB/C 18 TAB ratio of 12. The catalytic results of Friedel Crafts Acylation (FCA) of 2-methoxynaphthalene (2-MN) reaction prove that the synthesis of the larger mesopores via swelling in this material preserves accessibility of catalytic sites. The addition of swelling agents and cosolvents decreases the mesopore volume as a result of a lower NaOH activity, and conducting syntheses with a higher NaOH concentration compensates for this. The effects of mesopore expansion could not be achieved postsynthetically, by treating an as-made conventional mesoporous Y material with TMB swelling agent. This emphasizes the importance of retaining flexibility in the surfactant assembly when performing mesopore expansion via swelling that is driven by non-covalent interactions. [Display omitted] • Supramolecular approach expanded pore size to 6.8 nm in Y Zeolite. • 1,3,5-trimethylbenzene showed a stronger swelling effect than para -xylene. • The addition of cosolvent s acts as pore-size and porosity modulators. • NaOH activity decreased by organic additives and offset by higher concentration. • Large pores preserved catalytic accessibility in 2-methoxynaphthalene acylation. [ABSTRACT FROM AUTHOR]

A set of Y-type zeolites with Si/Al atomic ratios between 7–45 were studied as catalysts in the aminocyclization reaction between acrolein and ammonia to produce pyridine and 3-picoline. The catalytic activity tests at 360 °C revealed that the acrolein conversion increased in the order Z45 < ZY34 < ZY7 < ZY17, in agreement with the increase of the total acidity per gram of catalyst. In all cases, pyridine bases and cracking products (acetaldehyde and formaldehyde) were detected in the outflow from the reactor. The total yield of pyridines was inversely proportional to the total acidity for the catalysts, which presented large surface areas and micro- and mesoporosity. The selectivity towards 3-picoline was favored when using catalysts with a Brønsted/Lewis acid sites ratio close to 1. The formation of pyridine occurred more selectively over Lewis acid sites than Brønsted acid sites. The deactivation tests showed that the time on stream of the catalysts depended on the textural properties of zeolites, i.e., large pore volume and large BET area, as evidenced by the deactivation rate constants and the characterization of the spent catalysts. The physicochemical properties of the catalysts were determined by XRD, UV-vis, and Raman spectroscopies, infrared spectroscopy with adsorbed pyridine, N2 physisorption, and SEM-EDXS. After the reaction, the spent catalysts were characterized by XRD, Raman spectroscopy, TGA, and SEM-EDXS, indicating that the uniform deposition of polyaromatic species on the catalyst surface and within the porous system resulted in the loss of activity.

The ultra-deep removal of thiophene is essential for the conversion of coke oven gas to methane and metal modified Y zeolite has excellent thiophene adsorption capacity. The effects of temperature on chemisorption between metal modified Y zeolite and thiophene and the reductive gases in coke oven gas on the thiophene adsorption performance still remains ambiguous. To address the aforementioned aims, series of NaMY (M = Ce, Ni, Zn and Ag) were prepared via ion-exchanged with Na+ of NaY, and two comparable sets of thiophene adsorption evaluation were conducted in a fixed bed reactor: (1) NaY and NaMY were evaluated at different temperatures in simulated coke oven gas, and (2) NaCeY was evaluated in N2 and different reductive atmospheres. The results show that NaNiY, NaZnY and NaAgY could adsorb thiophene via π-complexation, however, NaCeY mainly through S-Ce bond. Π complexation becomes weak above 150 °C, and the strength of S-Ce bond varies little when the temperature rises to 250 °C. Compared with that of other sorbents, the breakthrough adsorption capacity for thiophene (Qb-thiophene) of NaAgY reaches the highest 144 mg/g at 100 °C, but decreases sharply when temperature rises to 200 °C. NaCeY has relatively low variation in Qb-thiophene from 100 °C to 200 °C. Moreover, Ce(IV) in NaCeY is more favorable for thiophene adsorption than Ce(III) in coke oven gas and the presence of H2 and CO would reduce the desulfurization activity of NaCeY. For the industrial utilization of thiophene ultra-deep removal, NaAgY has an excellent potential below 150 °C, while NaCeY with more Ce(IV) has a good prospect at 150–250 °C. [ABSTRACT FROM AUTHOR]

A series of aMn-bCu/Y catalysts with different Mn/Cu loads were synthesized by impregnation method, and investigated for the catalytic ozone oxidation of toluene at room temperature.The catalysts were characterized by N2-physisorption measurements, powder X-ray diffraction, NH3-temperature programmed desorption, H2-temperature programmed reduction and X-ray photoelectron spectroscopy.The results show that the Mn/Cu loading amounts have significant influences on the specific surface area, crystalline phase, surface acidity, reduction property and surface chemical state, consequently affecting the catalytic performance.Among the Mn/Cu loaded catalysts, 18 Mn-6 Cu/Y with the mass fractions of Mn 18% and Cu 6%,has the highest toluene removal efficiency which is due to its higher manganese dispersion, appropriate acidity, good redox ability, well lattice oxygen mobility and rich Mn4+particles.After 6 h tests at room temperature, 18 Mn-6 Cu/Y catalyst maintains the high toluene conversion of 98% as well as the CO2 selection of 82.1%.But in contrast, there are decreases in varying degrees with other loading amounts. [ABSTRACT FROM AUTHOR]

In this study, a density functional theory method is employed to investigate the reaction mechanisms of dimethyl carbonate (DMC) formation, through oxidative carbonylation of methanol, on four types of Y zeolites doped with Cu+, Cu2+, Cu2O and CuO, respectively. A common chemical route is found for these zeolites and identified as, first, the adsorbed CH3OH is oxidized to CH3O species; subsequently, CO inserts into CH3O to CH3OCO, which reacts with CH3O to form DMC rapidly; and finally, the adsorbed DMC is released into the gas phase. The rate-limiting step on Cu2+Y zeolite is identified as oxidation of CH3OH to CH3O with activation barrier of 66.73 kJ·mol−1. While for Cu+Y, Cu2O-Y and CuO-Y zeolites, the rate-limiting step is insertion of CO into CH3O, and the corresponding activation barriers are 63.73, 60.01 and 104.64 kJ·mol−1, respectively. For Cu+Y, Cu2+Y and Cu2O-Y zeolites, adsorbed CH3OH is oxidized to CH3O with the presence of oxygen, whereas oxidation of CH3OH on CuO-Y is caused by the lattice oxygen of CuO. The order of catalytic activities of these four types of zeolites with different Cu states follows Cu+Y ≈ Cu2O-Y > Cu2+Y > CuO-Y zeolite. Therefore, CuY catalysts with Cu+ and Cu2O as dominated Cu species are beneficial to the formation of DMC.

Cheap alumino-silicate materials such as clay materials and Y zeolite were selected for the catalytic pyrolysis of waste engine oil in a fixed bed reactor. A cheaper route of Y zeolite synthesis involving hydrothermal activation of the raw clay and hydrothermal synthesis was employed. X-ray diffraction technique, scanning electron microscopy, Fourier transform infra-red, and nitrogen desorption method were used to characterize the intermediate phases formed during the hydrothermal treatment of the clay and the synthesized Y zeolite during the hydrothermal processes. The chemical compositions of the liquid phase of catalytic pyrolysis were characterized by gas chromatography coupled with mass spectroscopy (GC–MS). The results revealed that the alkaline concentration strongly influenced the activation of the raw clay to obtain a useful phase for the subsequent synthesis of the Y zeolite. The synthesis improved the surface area from 29 m2/g for the clay to 745 m2/g for the zeolite. The catalytic pyrolysis resulted in diesel fractions of 64.8 and 54.7%, respectively for the Y zeolite and the clay. It was observed that the gasoline fractions increased to 20.5 and 19.1%, respectively for the zeolite and the clay. In the diesel fraction, the zeolite selectively improved the yield of the cyclo-alkanes which are key constituents in terms of the quality of diesel. Y zeolite was successfully derived from a natural clay and tested in the pyrolysis of waste engine oil. The synthesis route provides the opportunity to improve the catalytic property of the natural clay. [ABSTRACT FROM AUTHOR]

A series of Y zeolites with different pore properties was prepared as a support for hydrocracking catalysts for the production of BTEX (benzene, toluene, ethyl-benzene, and xylene) from tetralin. Some important characterizations, including N2 adsorption–desorption, NH3-TPD, Py-IR, and HRTEM, were applied to obtain the properties of different catalysts. Meanwhile, the tetralin hydrocracking performances of those catalysts were investigated on a high-pressure fixed-bed microreactor. The results showed that Si/Al ratio is the core property of zeolites and that the increase in the Vmicro/Vmeso of zeolites could facilitate the formation of BTEX products by hydrocracking tetralin. The method of hydrocracking tetralin was proposed. It was also found that the hydrogenation–cracking path was controlled by aromatic saturation thermodynamics, and strong acidity aided the backward shift of equilibrium temperature.

Coke formation on n-butene cracking catalyst is the main reason for the reducing of its lifetime. To study the effects of acidity and textural properties on the coke formation process, a series of HY zeolite-type catalysts were prepared by ammonium hexafluorosilicate treatment (AHFS). NH3-TPD and Py-IR-TPD were used to systematically study the change law of zeolite acidity. It was found that with the increase of AHFS concentration, the acid density decreased, whereas the ratio of Brønsted acid to Lewis acid first increased and then decreased. Meanwhile, the percentage of Brønsted acid inside the supper cages increased and the strength of Brønsted acid increased with the degree of dealumination. Combined with in situ IR study on coke formation, the relationship between coking and acid site was revealed. It was found that the rate of coke formation on zeolites was affected by acid density, which is the rate of coke formation decreased with the decline of acid density. When the acid density remains at the same level, it was the acid strength that determined the coke formation rate—the stronger the acid strength, the faster the coke formation rate.

The study investigates the catalytic properties of microporous (H–Y) and micro-meso-macroporous (H–Y-mmm) FAU-type zeolites in the synthesis of 2-methyl-5-ethylpyridine (MEP) by the reaction of acetaldehyde with ammonia. At 150°C, an acetaldehyde to ammonia molar ratio of 1 : 3, and a catalyst content of 10 wt %, a MEP yield of 58% (0.95H–Y) and 63% (0.95H–Y-mmm) was achieved with a MEP selectivity of 91 and 93%, respectively. The examination of the catalyst stability revealed that hierarchical H–Y-mmm zeolites ensure a 100% MEP selectivity during 4–5 cycles with a slight decline in the catalytic activity, while H–Y zeolites are active during the first cycle only. [ABSTRACT FROM AUTHOR]

This paper describes the investigation of the individual effects of the introduced quantities of rare-earth elements (REE) and of SiO2/Al2O3 ratio on the physicochemical characteristics (textural properties and acidity) of Y zeolite, as well as on the catalytic activity of petrochemical cracking catalysts based on the zeolites prepared, during the conversion of hydrotreated vacuum gas oil (HTVGO). The amounts of REE oxides and the zeolite SiO2/Al2O3 ratio were quantified independently. An increase in REE oxide content in zeolite reduces its acidity. With an increase in SiO2/Al2O3 ratio at constant REE oxide content, the concentration of acid sites decreases, while the specific surface area and pore volume change only insignificantly. A growth in the REE2O3 content leads to a decline in the olefin yield from HTVGO cracking. Catalytic tests of the prepared catalysts demonstrated that an increase in SiO2/Al2O3 ratio enhances the C2–C4 olefin yield from HTVGO cracking as a result of the smaller contribution of hydrogen transfer reactions. [ABSTRACT FROM AUTHOR]

Zirconium-modified Y zeolites (ZrUSY) were prepared by impregnation of the zeolite with anhydrous-ethanol and aqueous ion exchange methods. The ZrUSY samples were characterized by powder X-ray diffraction, nitrogen physisorption, and Fourier transform infrared spectroscopy. The results indicated that ZrUSY prepared by the impregnation with anhydrous-ethanol method showed higher crystallinity, specific surface area and hydrothermal stability. The incorporation of Zr into other Y zeolites leads to an increase of the Brønsted acid site concentration and a decrease of the Lewis acid site concentration compared to the ultra-stable Y zeolite (USY). The ZrUSY was much more favorable towards heavy oil FCC conversion with decreasing coke yield and improving olefins selectivity.

The ultra-deep removal of thiophene is essential for the conversion of coke oven gas to methane and metal modified Y zeolite has excellent thiophene adsorption capacity. The effects of temperature on chemisorption between metal modified Y zeolite and thiophene and the reductive gases in coke oven gas on the thiophene adsorption performance still remains ambiguous. To address the aforementioned aims, series of NaMY (M = Ce, Ni, Zn and Ag) were prepared via ion-exchanged with Na+ of NaY, and two comparable sets of thiophene adsorption evaluation were conducted in a fixed bed reactor: (1) NaY and NaMY were evaluated at different temperatures in simulated coke oven gas, and (2) NaCeY was evaluated in N2 and different reductive atmospheres. The results show that NaNiY, NaZnY and NaAgY could adsorb thiophene via π-complexation, however, NaCeY mainly through S-Ce bond. Π complexation becomes weak above 150 °C, and the strength of S-Ce bond varies little when the temperature rises to 250 °C. Compared with that of other sorbents, the breakthrough adsorption capacity for thiophene (Qb-thiophene) of NaAgY reaches the highest 144 mg/g at 100 °C, but decreases sharply when temperature rises to 200 °C. NaCeY has relatively low variation in Qb-thiophene from 100 °C to 200 °C. Moreover, Ce(IV) in NaCeY is more favorable for thiophene adsorption than Ce(III) in coke oven gas and the presence of H2 and CO would reduce the desulfurization activity of NaCeY. For the industrial utilization of thiophene ultra-deep removal, NaAgY has an excellent potential below 150 °C, while NaCeY with more Ce(IV) has a good prospect at 150–250 °C.

• Successfully synthesis of well crystallized Y zeolite from industrial bentonite. • No the P zeolite formation due to using rick husk ash as second silica source. • Synthesis of NiMo/Al 2 O 3 catalyst via combustion method using citric acid as fuel. • High catalytic activity toward hydrocracking of heavy oil using dual-bed reactor. • Assessment the properties of Y zeolite after utilizing in hydrocracking reaction. A series of Ni-Mo/Al 2 O 3 -Y hybrid nanocatalysts were synthesized for hydrocracking of heavy oil. The well crystallized Y zeolite was synthesized from mineral bentonite and rice husk ash by a two-step synthesis method. The solution combustion method was applied to develop a fast and simple technique for preparing of alumina-supported NiMo catalyst with high hydrodesulfurization activity. Such activity may be due to the morphological and textural modification as a consequence of the release of a high amount of exhaust gases during the combustion process. The XRD analysis revealed that the P zeolite was a competitive phase presented in the obtained product that could be eliminated using a two-step synthesis method. Compared to a one-step method, the pore volume and external surface area of the synthesized zeolite by the two-step method increased by 74 and 62%, respectively. The hydrocracking results illustrated that the synthesized zeolite was able to convert 66% of heavy oil to lighter products and reduce the viscosity up to 60%. Furthermore, the amount of sulfur removal was found to be 58%. The spent catalyst characterization suggested that the type of deposited coke was hard coke with the unsaturated aromatic ring which could be responsible for the pores blockage after the cracking reaction. [ABSTRACT FROM AUTHOR]

A bimetal-exchanged NaY zeolite (Cu(I)-Y(III)-Y) with a desirable adsorptive desulfurization (ADS) performance was prepared and characterized by means of X-ray diffraction, specific surface area measurements, X-ray fluorescence spectrometer, X-ray photoelectron spectroscopy, thermal gravity analysis and Fourier transform infrared spectroscopy. The effect of Y(III) ions on ADS in the presence of the xylenes was investigated. Results indicated that the ADS performance of Y(III)-Y is higher than that of most reported CeY. The Y(III)-based Cu(I)-Y(III)-Y demonstrated the higher breakthrough loading than those of reported Ce(III)/Ce(IV)-based transition metal Y zeolites, showing that Y(III) ions play a promoting role in improving the ADS selectivity. For Cu(I)-Y(III)-Y, a new strong S-M interaction (S stands for sulfur, while M stands for metal) active site was formed, which might be caused by the synergistic effect between Cu(I) and Y(III). The Cu(I)-Y(III)-Y, which combined the advantages of Cu(I)-Y and Y(III)-Y, is a kind of promising adsorbent. The breakthrough loading decreased in the order of Cu(I)-Y(III)-Y > Y(III)-Y > Cu(I)-Y, and the effect of xylene isomers on the sulfur removal was in the order of ortho-xylene > meta-xylene > para-xylene, which exhibited the same trend with the bond order of xylenes. [ABSTRACT FROM AUTHOR]

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• Various zeolite supported Ni-W catalysts were used for hydrocracking activity of hydrotreated light cycle oil. • Highest mono-aromatics yield was obtained over Ni-W supported Beta zeolite catalyst. • Established the metal support interaction, and acidity properties correlated with activity. The bi-functional catalysts comprising non-noble metals such as Ni-W supported on zeolites were prepared to study hydrocracking of hydrotreated Light Cycle Oil (LCO) conversion into mono-aromatics. The three Ni-W supported zeolite catalysts with mixture of Y and Beta (Catalyst-A), Y (Catalyst-B), and Beta zeolites (Catalyst-C) were prepared by wetness impregnation method and characterized by using different techniques to understand the physico-chemical properties. The characterization results indicated that Ni-W supported on Beta zeolite catalyst has higher overall acidity and strong interaction between the H 2 W 12 O 40 and Ni2+ ions than Ni-W supported on mixture of Y & Beta, and Y zeolites. Furthermore, Beta zeolite catalyst exhibited tetrahedral tungstate species, which are due to strong interaction between support and metal ions. Among these catalysts, Ni-W supported on Beta zeolite catalyst showed high conversion for mono-aromatic 2 ring, and di-aromatics and selectivity towards mono-aromatics (43.5%). The high conversion of this catalyst could be due to higher total acidity and the presence of tetragonal tungsten species. High selectivity of mono-aromatics may be due to larger average pore diameter of the Beta zeolite. [ABSTRACT FROM AUTHOR]

Alkali treatment is widely used on aluminosilicate zeolites with high Si/Al ratios in order to fabricate mesopores in the framework. However, for zeolites with low Si/Al ratios, the effect of alkali treatment on the pore and framework structure needed further study. In this work, Y zeolite is treated with NaOH solutions of different concentrations and is used as the support for Cu-based catalysts for oxidative carbonylation of methanol to dimethyl carbonate. The physicochemical properties of the supports and corresponding catalysts are characterized by N2 adsorption–desorption, X-ray diffraction, X-ray fluorescence, transmission electron microscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and H2-temperature-programmed reduction analyses. The results show that no obvious mesopores are formed under alkali treatment, even at high NaOH concentration. However, amorphous species present in the micropores of Y zeolite are removed, which increases the micropore surface area as well as the crystallinity. Simultaneously, the cage structure is partially destroyed, which also leads to a slight increase of the pore volume and surface area. The altered micropore structure eventually increases the content and accessibility of the exchanged Cu species, which is beneficial to the catalytic activity. When the concentration of NaOH is 0.6 M, the space time yield of dimethyl carbonate for the corresponding catalyst was 151.4 mg g−1 h−1 which is 3.3-fold higher than that of the untreated-Y-zeolite-supported Cu catalyst. However, further increasing the alkali treatment strength can seriously destroy the basic aluminosilicate structure of the Y zeolite and decrease its intrinsic ion-exchange capacity. This results in the formation of agglomerated CuO on the catalyst surface, which was not conducive to catalytic activity. [ABSTRACT FROM AUTHOR]

In this study, Y zeolite nanocrystals were synthesized without an organic template and were used as a support for bifunctional nanocatalysts in the hydroisomerization of n‐octane. Different types of catalysts were synthesized by loading Pt, Cr, and phosphomolybdic acid (HPMo) on Y zeolite nanocrystal supports and were characterized by X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscope (FE‐SEM), and transmission electron microscope (TEM) analysis. The Cr‐Pt/HPMo‐Y nanocatalyst with a surface area of approx. 600 m2/g showed the best performance in the hydroisomerization of n‐octane. The optimization of n‐octane hydroisomerization over bifunctional nanocatalysts supported on nanocrystalline Y zeolite, in the presence of H2 gas, was applied based on the response surface methodology (RSM) and Box–Behnken design (BBD) template. The effect of three different process variables on the yield of iso‐alkanes as the purpose process was determined. Experiments were carried out using a fixed‐bed microreactor under different ranges of weight hourly space velocity (WHSV) (A = 0.5–1.5 hr−1), H2 to n‐C8 molar ratio (B = 1:1–3:1), and reaction temperature (C = 200–300°C). The RSM proved that the temperature variable had the greatest impact on the hydroisomerization reaction yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu and Ce in ion-exchanged Y exhibit synergy through electronic interactions. • Selectivity for thiophenic sulfur over similar aromatics is limited. • Adsorption strength is significantly increased in bimetallic CuCeY. • Sulfur is adsorbed via π-complexation between Cu 3d and C = C π and π* orbitals. Sulfur compounds present in petroleum fuels are a significant contributor to environmental pollution through the formation of sulfur oxides during combustion. To mitigate release of these pollutants by reducing the sulfur content of transportation fuels, adsorptive desulfurization (ADS) under ambient conditions has been studied. Sorbent materials, in particular Cu and Ce ion-exchanged Y (CuCeY), have exhibited excellent ADS performance, however, the basis for this improved adsorption has not been fully understood. For this purpose, Density Functional Theory (DFT) calculations investigated the adsorption mechanisms of thiophenic sulfur on CuCeY. Calculated adsorption enthalpies ΔH ads agree with experimental results, indicating exothermic adsorption strength following the order of: Y < CeY < CuY < CuCeY. The preferential adsorption mechanism is via π-complexation between Cu and π-bonded C = C in the adsorbate. Natural Bond Orbitals (NBOs) further studied the electronic interactions during adsorption, and demonstrated synergy between Cu and Ce cations via electron sharing. Bonding and antibonding NBO pairs between Cu and adsorbed sulfur combined with significant delocalizations of the electronic structure provides further reasoning for the superior adsorption of sulfur on CuCeY. [ABSTRACT FROM AUTHOR]

Dimethyl carbonate is an environmentally friendly molecule with increasing applications as reactant, solvent, and fuel additive. Oxidative carbonylation of methanol, with reactants in the gas phase and catalyzed by copper-exchanged Y zeolites, is a promising alternative route for dimethyl carbonate production. This work is focused on the improvement of the catalyst formulation and preparation methods. Catalysts were prepared using two methodologies: solid-state ion exchange and liquid-ethanol ion exchange. Five different copper salts were used as precursors and the NH 4 + and Na+ forms of the Y zeolite as supports. The Na+ form of the Y zeolite removed the Brønsted acidity of the support and, therefore, the reaction rate of acid-catalyzed undesired dehydration and decomposition reactions was reduced. The use of copper chloride salts as precursors was crucial to obtain suitable catalysts for dimethyl carbonate formation. Among all the tested catalysts, those prepared using CuCl 2 precursor and the Na-Y zeolite by the liquid-ethanol ion exchange method showed the best performance (0.72 mol DMC /mol Cu h). This catalyst exhibited the highest surface chloride content and Lewis acidity. [Display omitted] • Dimethyl carbonate from gas-phase methanol oxidative carbonylation. • Preparation method, precursor and support of Cu/Y zeolite catalyst optimized. • Copper chloride precursors are needed to be active towards dimethyl carbonate. • The most active catalyst (CuCl 2 -Na Y zeolite) has the highest Lewis acidity. [ABSTRACT FROM AUTHOR]

• CY zeolite after oxalic acid-high temperature steam-citric acid treatment still retains the intact framework structure. • Elucidated the mechanism of dealumination of CY zeolites by oxalic acid-high temperature steam-citric acid treatment. • The dealumination treatment improved the specific surface area and average pore size of CY zeolite pellets. • The modified CY zeolites have good adsorption capacity of VOCs under both dry and humid conditions. Y Zeolite and its ultra-stabilized hierarchical derivative (USY) as absorbents have low adsorption capacity for VOCs under humid conditions thus limits their industrial applications. It is well known that high SiO 2 /Al 2 O 3 ratio (SAR) can improve the hydrophobicity of zeolite, and the increase of pore volume can enhance the adsorption performance. In the present work, SAR and the pore size of CY were enlarged by oxalic acid-high temperature steam-citric acid treatment, as the framework aluminum in the zeolite was removed and maintaining its structural integrity. The surface morphology and structure of samples were characterized by XRD, BET, TEM, SEM and TG. 27Al MAS NMR, XPS and Pyridine infrared analysis the mechanism of aluminum removal from the CY framework. The dynamic adsorption properties of the samples were systematically investigated with toluene selected as representative volatile organic compounds. The hydrophobicity of the samples was investigated by static water adsorption, and the adsorption kinetics model of the samples were plotted to study their adsorption characteristics. N 2 adsorption-desorption results showed that the modified CY material has larger surface area, wider pore size and larger microporous volume than the raw material. On the other hand, with the improved SiO 2 /Al 2 O 3 ratio and hydrophobicity, the modified USY also exhibited excellent adsorption performance under humid conditions, with 4.2 times more capacity to adsorb toluene. Therefore, this method can provide effective adsorption of VOCs in humid environments. [ABSTRACT FROM AUTHOR]