Hβ Zeolite Research Articles

Optimizing propylene production via acetone hydrodeoxygenation: Insights from catalytic studies with Cu/γ-Al2O3 and Hβ zeolite

Propylene is a crucial light olefin in the petrochemical industry and can be produced via acetone hydrodeoxygenation, which involves two sequential reactions: first, acetone undergoes hydrogenation catalyzed by metallic sites, followed by the dehydration of the resulting isopropanol catalyzed by acidic sites. In this study, propylene production through acetone hydrodeoxygenation was investigated using a physical mixture of 35 wt% Cu/γ-Al2O3 and Hβ zeolite to investigate how various reaction parameters affect acetone conversion and propylene yield. Using the experimental design methodology, empirical models were developed to correlate acetone conversion (Xacet) and propylene yield (Yprop) with the ratio of 35 wt% Cu/γ-Al2O3 to Hβ (CR), total catalyst weight (Cw), hydrogen volumetric flow rate (FH2) and reaction temperature (T). The maximum propylene yield achieved in the catalytic tests was 73.46 %. A long-term test demonstrated the catalyst's reusability, remaining active even after 22 hours of reaction with only a slight decrease in propylene yield. Analysis of the experimental data revealed that increasing T and Cw positively affected propylene yield, whereas higher CR and FH2 had negative effects. According to the Pareto chart, reaction temperature was the most influential variable for propylene yield, followed by CR, FH2 and Cw. For acetone conversion, the order of significance among the variables was T >CR >Cw >FH2.

Effect of solid acid catalyst coupled decolorization process on the physicochemical properties and bioactive and volatile compounds of sesame oil

SummaryIn this study, the effects of citric acid‐loaded Hβ zeolite (F), activated clay and their modified decolorizers on the nutrients, volatile compounds and harmful substances of sesame oil in the decolorization process were evaluated. The results showed that the decolorization effect of F was second only to that of activated clay, the yield of F‐treated sesame oil sample was not significantly different from that of other decolorizers. The formation of asarinin was detected only in the sesame oil samples treated with F and H (zinc chloride‐activated clay). Compared with the activated clay‐treated sesame oil samples, the retention of tocopherols in the F‐treated sesame oil sample was significantly increased by 23.11%, and the retention of phytosterols was increased by 4.85%. The removal rate of the harmful substances Norharman and Harman in the F‐treated sesame oil sample was 96.79%, which was second only to that of the activated clay. Additionally, the removal rate of the total volatile compounds was the highest at 69.47%. The effects of different decolorizers on the sesame oil samples were closely related to the specific surface area, pore size and surface acidic sites of these decolorizers. This study could provide ideas for the industrial application of leached sesame oil, such as cosmetics and base oils.

Dehydration of lactic acid to prepare acrylic acid over Hβ zeolite modified by acid treatment and Rb ion-exchange

The catalytic dehydration of bio-derived lactic acid into acrylic acid is one of the research hotspots in the field of green chemical industry, but the selectivity of acrylic acid and the stability of catalyst still face great challenges. In this work, a modified Hβ zeolite catalyst was prepared by sequential nitric acid treatment and Rb ion-exchange for the gas phase dehydration of lactic acid to prepare acrylic acid. The nitric acid treatment increased the content of Lewis acid sites together with the decrease of the content of Bronsted acid sites, which enhanced the dehydration and hindered the decarboxylation/decarbonylation of lactic acid. Consequently, the selectivity of acrylic acid was improved. The Rb ion-exchange not only significantly decreased the density of acidic sites but also regulated the density of basic sites of the catalyst. The optimal 0.1NA-6.8Rb/Hβ catalyst treated by 0.1 mol/L of nitric acid and 6.8 wt% of Rb ion-exchange contributed to a 99.28 % conversion of lactic acid and 76.72 % yield of acrylic acid. The catalyst showed a better stability and was easy to regenerate, maintaining 87.35 % conversion of lactic acid and 62.49 % yield of acrylic acid, respectively, after two cycles of consecutive 48 h reaction.

Solvent-promoted selective chemocatalytic hydroxymethylation of biomass furanic compounds

Functionalizing biomass-derived furanic chemicals is of great importance towards biorefinery processes but challenging, especially working at elevated substrate concentrations. We herein report the intervention of 1,4-dioxane co-solvent availably to catalyze hydroxymethylation of furfuryl alcohol (FA) in formalin over Hβ zeolite, giving high yield to 2,5-dihydroxymethylfuran (DHMF), a versatile building block. Impressively, the facilitating effect of 1,4-dioxane on DHMF production became more pronounced with increasing FA feeding concentration, and the yield raised from 19.5 % to 67.8 % from a high FA concentration of 10 wt%. The 1,4-dioxane served not only as a catcher of formaldehyde hydrate to access substrate FA, but also as a shield to restrain undesirable condensation side-reactions. The developed protocol demonstrated an excellent universality in boosting the hydroxymethylation of electrondrawing-group-free furanic molecules (e.g., furan, 2-methylfuran). The understanding of these solvation effects can be employed to effectively manipulate and improve the hydroxymethylation of furanic compounds.

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

Non‐Oxidative Conversion of Methanol to Dimethyl Ether, Methyl Formate and Dimethoxymethane over Cu/Hβ Catalyst: Tailoring Product Selectivity

AbstractHerein, we present the production of either dimethyl ether (DME), methyl formate (MF) or dimethoxymethane (DMM), representing pivotal molecules for the green transformation of fuels and chemical industry, by the non‐oxidative gas‐phase conversion of methanol under the same reaction conditions. The product selectivity is optimized by tailoring the acidic and dehydrogenative sites of the bifunctional Cu/Hβ catalyst system by varying the SiO2/Al2O3 ratio of the Hβ zeolite (25 and 520) and the Cu loading (0.5 and 20 wt %). At 240 °C, >99 % (DME), 74.5 % (MF), and 77.3 % (DMM) selectivity is achieved with the respective catalysts 0.5 %Cu/Hβ(25), 20 %Cu/Hβ(520), and 0.5 %Cu/Hβ(520). High acidic site concentration catalyzes DME formation, while the presence of Cu+ species is crucial for DMM formation, and Cu0 species mainly catalyze MF formation. A highly dynamic reaction behaviour is observed, when the dehydrogenative functionality is dominant (i. e., in the production of MF or DMM), presumably due to the dynamic nature of the Cu oxidation state, which is in turn influenced by possible by‐products (H2 and H2O). While the catalytic activity in DME synthesis over 0.5 %Cu/Hβ(25) is remarkably stable over 1500 min TOS, the activity in MF and DMM production over 20 %Cu/Hβ(520) and 0.5 %Cu/Hβ(520), respectively, can be successfully regenerated.

NaOH-Treated Hβ Zeolite: A Highly 4-Tert-butyl-phenol Selective Catalyst for Alkylation of Phenol with Tert-Butanol

NaOH-Treated Hβ Zeolite: A Highly 4-Tert-butyl-phenol Selective Catalyst for Alkylation of Phenol with Tert-Butanol

Solvent-free Markovnikov hydroamination of vinylarenes with carboxamides: a heterogeneous catalytic approach using Hβ zeolite

A novel heterogeneous catalytic method has been developed to facilitate the intermolecular Markovnikov hydroamination of vinylarenes with benzamides using Hβ zeolite in a solvent-free environment.

Alkylation of α-pinene with isobutene/isobutane over Hβ zeolite

Hybrid alkylation performance of α-pinene with isobutene/isobutane towards bio-based high-energy-density fuels using Hβ-25n zeolite as a catalyst.

Catalytic cascade gas-phase heterocyclization of lactic acid and aniline into quinolones over mesoporous Hβ zeolite

High-value quinoline derivatives were synthesized by vapor-phase cascade heterocyclization via the coupling of biomass-derived lactic acid with aniline, using mesoporous HBeta zeolites as a green and efficient heterogeneous catalyst.

Synthesis of JP-10 analogues high-density fuels via one-pot Diels-Alder/hydrodeoxygenation reaction

JP-10 is the most widely used petroleum based fuel in military aircraft due to its high energy density and excellent cryogenic properties. However, the high price and low availability limit its application in civil aviation. Herein, JP-10 analogues fuel was first synthesized via one-pot Diels-Alder/hydrodeoxygenation reaction using biomass-derived furans and petroleum-derived norbornene. Hβ zeolite with Si/Al ratio of 25 exhibits the best catalytic performance (yield of 75.9 %) for Diels-Alder reaction ascribed to its large surface area and high acid concentration, especially the high ratio of Brønsted/Lewis acid sites. Kinetics research indicates that Diels-Alder reaction of norbornene and 2-methylfuran shows the apparent activation energy of 45.67 kJ/mol, much lower than that of norbornene dimerization (52.48 kJ/mol) and 2-methylfuran trimerization (63.61 kJ/mol). Importantly, the synthesized fuel has much higher density, volumetric neat heat of combustion and better cryogenic viscosity (0.943 g mL−1, 40.39 MJ/L and 12.9 mm2 s−1 at −40 °C) than classic JP-10 fuel (0.936 g mL−1, 39.41 MJ/L and 18.6 mm2 s−1 at −40 °C). This work provides an efficient and promising route to produce high-performance JP-10 fuel alternatives through co-conversion of biomass and petroleum derivatives.

1,4-Dioxane intervention enables simultaneous valorization of biomass-based C5 and C6 sugars to furfural over Hβ zeolite

The simultaneous valorization of biomass-based C5 and C6 sugars to furfural, a versatile intermediate, is of great significance to fully utilize biomass components. Inability to effectively transform C6 sugars remains a major barrier toward this challenging goal. We herein report the 1,4-dioxane-mediated solvent system with Hβ zeolite catalyst for the transformation of glucose giving high yield to furfural (57%). The maintenance of intrinsic balanced Lewis and Brønsted acid sites from Hβ zeolite that is credited to the positive solvent effect of 1,4-dioxane is highly conductive to the selective C-C bond cleavage of glucose. Also importantly, the introduction of proper amount of H2O into the reaction system results in a high formation rate and an improved selectivity toward furfural due to the induction of highly reactive acyclic glucose. Glucose-to-furfural through 3-deoxyglucose should be more favorable than that via fructose. Impressively, the developed protocol can also be adapted to C5 sugars dehydration, and the one-pot conversion of glucose and xylose mixtures gains a furfural yield as high as 63%. The activation energy barrier for furfural production is higher from glucose compared to xylose. This work not only develops a promising protocol for furfural production simultaneously from C5 and C6 sugars but also provides insights into the mechanistic role of the solvent 1,4-dioxane to availably manipulate the acid-catalyzed conversion of C6 sugars.

Production of higher hydrocarbon-pool from bio-ethanol for fuel applications

In a way to explore the inherent acidity and porosity properties of zeolites for the conversion of renewable biomass-derived ethanol into various fuel stocks, three types of zeolites; HZ, HY, and HB have been studied in their proton form. The studies indicated the formation of catalyst-dependent hydrocarbon composition of the product falling in gasoline and jet fuel for the specific end-use applications. The flexibility in product choice facilitated by changing the catalyst makes the present process suitable for industrial applications based on the nature of product in demand. At optimized temperature and pressure reaction conditions, HB zeolite produced >40 wt% jet fuel hydrocarbons (T = 400 °C and P = 50 bar), HZ produced 53 wt% octane gasoline (RON >100) and HY zeolite produced 25 wt% of olefins in liquid product. The novelty of the present process lies in its simple, single-step, continuous-flow vapour-phase single catalytic process operating on zeolites bearing no metal function but possessing variable pore size and other catalytic properties required for producing higher range hydrocarbons from ethanol.

Double Hydroamination of Terminal Alkynes over Beta Zeolite‐Supported CuO Catalyst

AbstractAn effective and novel heterogeneous beta zeolite supported CuO (Cuβ) catalyzed double hydroamination of alkynes for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones has been achieved in a solvent‐free condition. Cuβ zeolite was synthesized by impregnation method. The synthesized Cuβ was characterized by X‐ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. Pure Hβ (18 % yield) or Nano CuO (44 % yield) displayed poor catalytic activity, whereas 1 % Cuβ (96 % yield) showed higher catalytic activity for double hydroamination of alkynes due to the synergistic effect of CuO and Hβ zeolite in the reaction. The new protocol offers an appealing approach to a number of di‐substituted quinazolinones with decent to excellent yields. The catalyst has been successfully recycled for up to 5 consecutive cycles.

Methane conversion to H2 and carbon nanofibers over supported Ni catalysts: A sustainable process through utilization of deactivated catalysts

AbstractThe renewable resource such as rice husk has been utilized to synthesize Hβ zeolite as a support for Ni catalysts for the production of clean hydrogen and carbon nanofibers (CNFs) by CH4 cracking at 550°C without any CO or CO2 formation. Hydrogen production rates and area of surface Ni are in good correlation, implying the optimum Ni loading of 25 wt % that demonstrated better hydrogen yields and CNFs. The electrochemical properties of the deactivated catalysts indicated that they were near semiconducting in nature, showing future prospects as carbon electrode materials. The physicochemical characteristics of the fresh, reduced, and used catalysts were rationalized by BET surface area, p‐X‐ray diffraction, temperature programmed reduction using H2, SEM, TEM, H2‐pulse chemisorption, and Raman spectroscopic analyses in conjunction with hydrogen rates.

HPW supported on ammonium hexafluorosilicate modified Hβ: Efficient catalysts for ethylene glycol and methyl tert‐butyl ether reaction with high selectivity and stability

A series of HPW supported on ammonium hexafluorosilicate (AHFs) modified Hβ (30HPW/Hβ‐Si(x)) was successfully prepared. After Hβ zeolite was pretreated with 0.1 mol·L−1 AHF's solution, the Brønsted/Lewis ratio of Hβ‐Si(0.1) increased compared with those of Hβ, and the strong acid density of 30HPW/Hβ‐Si(0.1) decreased compared with those of 30HPW/Hβ respectively. Strong acidic sites and Lewis acid sites are catalytic sites for by‐products diisobutene and ethylene glycol oligomers, which deposited on the catalyst result in the deactivation of catalysts. According to the results of characterization, the internal Si‐OH groups of Hβ (strong acidity sites) were filled with silicon of AHFs. The extraframework aluminum (strong acid sites) was removed by the H+, which is the hydrolysis of AHFs. In addition, the hydrophobicity of 30HPW/Hβ‐Si(0.1) was also improved compared with that of 30HPW/Hβ due to the SiO2/Al2O3 ratio of Hβ increased after treatment by 0.1 mol·L−1 AHFs solution. The 30HPW/Hβ‐Si(0.1) maintained an 80% conversion of methyl tert‐butyl ether and 100% selectivity to ethylene glycol mono‐tert‐butyl ether and DBE ethylene glycol bis‐tert‐butyl ether with 336 h of time on stream.

Gas-Phase Deoxygenation of Biomass Pyrolysis Tar Catalyzed by Rare Earth Metal Loaded Hβ Zeolite

Biomass pyrolysis tar (BPT) with a higher heating value of 24.23 MJ/kg was used as raw feed for the catalytic gas-phase deoxygenation (GDO) process using Hβ zeolite loaded with different amounts of active elements (Ce, La, and Nd). Acetone molecule was chosen as a model compound to test the activity of pure Hβ zeolite, 1 wt% Ce/Hβ zeolite, 5 wt% Ce/Hβ zeolite, 1 wt% La/Hβ zeolite, 5 wt% La/Hβ zeolite, 1 wt% Nd/Hβ zeolite, and 5 wt% Nd/Hβ zeolite at 400 °C and process time of 3 h. BPT characterization showed a wide range of oxygenated compounds with the main components including water: 0.71%, furfural: 5.85%, 4-ethylguaiacol: 2.14%, phenol: 13.63%, methylethyl ketone: 5.34%, cyclohexanone: 3.23%, isopropanol: 4.78%, ethanol: 3.67%, methanol: 3.13%, acetic acid: 41.06%, and acetone: 16.46%. BPT conversion using 1 wt% Ce/Hβ zeolite catalyst showed the highest values of degree of deoxygenation (DOD) (68%) and conversion (16% for phenol, 88% for acetic acid, and 38% for 4-ethlyguaiacol). Yields of water, liquid phase, and gas phase in the GDO reaction using 1%Ce/Hβ zeolite were 18.33%, 47.42%, and 34.25%, respectively. Alkyl-substituted phenols and aromatic hydrocarbons achieved the highest yields of 37.34% and 35.56%, respectively. The main interaction pathways for BPT-GDO are also proposed.

A comparative study of the catalytic nitration of toluene over bimetallic Ce‐Mn modified Hβ zeolite

AbstractBimetallic cerium‐manganese modified Hβ zeolite sample (Ce/Mn‐Hβ) was prepared by ultrasonic assisted impregnation method and applied in nitration of toluene. The characterization results show that the active components (Ce and Mn) are successfully introduced into the framework of Hβ zeolite. The catalyst shows excellent catalytic activity and reusability for the nitration of toluene, giving high para selectivity. Under optimized conditions, it gives 68.7% selectivity to para‐nitrotoluene at 88.6% conversion over Ce/Mn‐Hβ in the presence of acetic anhydride (Ac2O). The theoretical calculations indicate that the Ce/Mn bimetallic active sites in modified Hβ zeolite can easily activate the nitrification reagent (AcONO2), and the enhancement of para selectivity is owing to the steric hindrance of catalyst. Furthermore, the reaction mechanism was proposed by the combination of experimental results and theoretical calculations.

One-pot conversion of α-pinene into biomass high energy density fuel over a bifunctional zeolite catalyst

A shape-selective bifunctional catalyst (Rux/SOT-Hβ) was furnished by loading Ru onto the Hβ zeolite prepared via seed organic template (SOT) method using the seeds obtained via steam-assisted conversion (SAC) method. The Rux/SOT-Hβ catalyst exhibited both favorable acid-catalytic performance and hydrogenation performance in the two-stage one-pot conversion of α-pinene, enabling an energy-efficient process for producing biomass blended high energy density fuels (HEDF). The effect of preparation conditions of Hβ zeolite carrier, metal type, loading amount, and loading method on the catalytic performance of the bifunctional catalyst was investigated. After the optimization of the catalytic process over Ru1.2/SOT-Hβ using pinane as the reaction medium, the resulting liquid reaction mixture without undergoing further distillation and other operations was found to possess good biomass HEDF properties. Feasible recyclability of Ru1.2/SOT-Hβ catalyst in α-pinene one-pot conversion was also demonstrated by a 3-run recycling test.

Tandem conversion xylose to 2-methylfuran with NiCu/C catalyst

Nowadays, 2-methylfuran is urgently needed especially in pharmaceutical manufacture. However, the direct synthesis of 2-methylfuran via the efficient dehydration and hydrogenation of xylose usually requires a multistep reaction. Herein, a route of tandem conversion xylose to 2-methylfuran was developed. The xylose was firstly converted into furfural by Hβ zeolite, followed by the catalysis of furfural to 2-methylfuran over 0.5NiCu/C. Compared with two-step reaction, cascade strategy applied xylose conversion improved the 2-methylfuran yield rate by 41.5%. In general, this work expanded the application of tandem method for the enhancement of xylose effective conversion and provided a new biomass utilization technology.