Deactivation of Zeolite Catalysts in the Prins Reaction between Propene and Formaldehyde in the Liquid Phase

The Prins reaction between propene and formaldehyde was studied over H-BEA, H-FAU, H-MFI and H-MOR zeolites at 150 °C in liquid phase. It was found that the H-BEA sample is the most active and selective toward buta-1,3-diene; the H-MFI is a potential catalyst for 3-buten-1-ol synthesis, while H-FAU can be used for 4-methyl-1,3-dioxane production. It had been confirmed that zeolite textural and acidic properties influence catalyst behaviour: the acidic properties influence sample activity, while product distribution is controlled by pore volume and effective pore diameter. The sample’s deactivation process had been studied and the kinetic model of deactivation was proposed. It was shown that the deactivation rate for the H-MFI catalyst is four times greater than for the H-BEA catalyst, probably because its strong/weak acid sites ratio is much more high than for the H-BEA.

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Effect of Silica Base Catalyst on Transformation of Methanol to Hydrocarbon

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.751.512 ◽

2017 ◽

Vol 751 ◽

pp. 512-517 ◽

Cited By ~ 1

Author(s):

Supranee Lao-Ubol ◽

Phunthinee Somwongsa ◽

Pracha Laoauyporn ◽

Pasinee Panith ◽

Siriporn Larpkiattaworn ◽

...

Keyword(s):

Pore Diameter ◽

Fixed Bed ◽

Methanol Conversion ◽

Liquid Hydrocarbon ◽

Product Distribution ◽

Catalytic Performance ◽

Zeolite Catalysts ◽

Fixed Bed Reactor ◽

Phosphorus Species ◽

Methanol To Hydrocarbon

Five different types of silica catalyst (SBA-15, SBA-15-PO3H2, and three different Si/Al ratio of commercial zeolites (30, 80 and 280) were used to study the transformation of methanol to hydrocarbon (MTH). The aim of this study was to investigate the effect of pore diameter and acidity in the structure of silica catalysts on the process performances in terms of methanol conversion and hydrocarbon selectivity. The mesoporous silica catalysts were prepared by co-condensation method. The catalysts samples were characterized by GC-MS, XRD, BET, and NH3-TPD techniques. The catalytic performance of synthesized and commercial catalysts for MTH process was evaluated using a homemade fixed bed reactor at temperature (300°C). It was found that the liquid hydrocarbon product provided by zeolite catalysts is aromatic hydrocarbons-rich. High Si/Al zeolites with larger pore size lead to higher selectivity and yield to paraffins (C1-C7). In contrast to commercial zeolite catalyst, SBA-15 and its modification with phosphorus species showed no conversion under studied condition. These results indicate that both pore diameter and acidity influence the product distribution in methanol to hydrocarbon process.

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Co-Aromatization of n-Butane and Methanol over PtSnK-Mo/ZSM-5 Zeolite Catalysts: The Promotion Effect of Ball-Milling

Catalysts ◽

10.3390/catal8080307 ◽

2018 ◽

Vol 8 (8) ◽

pp. 307 ◽

Cited By ~ 3

Author(s):

Kang Yang ◽

Lingting Zhu ◽

Jie Zhang ◽

Xiuchun Huo ◽

Weikun Lai ◽

...

Keyword(s):

Ball Milling ◽

Acid Sites ◽

Weak Acid ◽

Zeolite Catalysts ◽

Coke Deposition ◽

Light Alkanes ◽

Promotion Effect ◽

Metallic Particles ◽

Butane Conversion

The ball-milling (BM) method benefits the stabilization and dispersion of metallic particles for the preparation of the PtSnK–Mo/ZSM-5 catalyst. Based on the TPR, H2-TPD, XPS, and CO-FTIR results, the Pt–SnOx and MoOx species were formed separately on the BM sample. During the aromatization of cofeeding the n-butane with methanol, the yield of the aromatics is 59 wt.% at a n-butane conversion of 86% at 475 °C over the Pt Mo BM catalyst. The more weak acid sites also contribute to the aromatics formation with the less light alkanes formation. For the Pt Ga catalysts, the slow loss of activity suggests that the BM method can restrain the coke deposition on the Pt-SnOx species, because of a certain distance between the Pt–SnOx and GaOx species on the surface of ZSM-5.

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Effect of Acid Treatment on the Properties of Zeolite Catalyst for Straight-Run Gasoline Upgrading

10.21926/cr.2104004 ◽

2021 ◽

Vol 1 (4) ◽

pp. 1-1

Author(s):

Ludmila Velichkina ◽

◽

Yakov Barbashin ◽

Alexander Vosmerikov ◽

◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Acid Treatment ◽

Catalytic Properties ◽

Fixed Bed ◽

Acid Sites ◽

Gasoline Fraction ◽

Zeolite Catalysts ◽

Acidic Properties

The objective of this research was to analyze the effect of different concentrations of nitric and hydrochloric acids on the structural, acidic, and catalytic properties of a post-synthetic treated ZSM-5 type zeolite at various temperatures. The properties of zeolite catalysts were determined using different methods, such as the Brunauer-Emmett-Teller (BET) method for specific surface area, temperature-programmed desorption (TPD) of ammonia method for acidic properties, and a flow-through unit with fixed bed catalyst (with upgrading straight-run gasoline fraction of oil) for catalytic activities of initial zeolite and acid-treated samples. The structural and acidic properties of both untreated and treated zeolites were investigated, and the effect of acid treatment on the catalytic properties of the samples in the course of upgrading the straight-run gasoline fraction of oil was determined. The post-synthetic treatment with aqueous nitric acid increased the specific surface area and volume of micropores of ZSM-5 zeolite, while the treatment with aqueous hydrochloric acid led to the formation of mesopores. Acid treatments of zeolite decreased the number of acid sites, mainly due to diminished concentration of low-temperature sites. The yield of liquid products in the conversion of straight-run gasoline fraction of oil, i.e., generation of high-octane gasolines with improved environmental features, was increased using acid-treated zeolites, which was due to the decrease in arene content.

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Understanding the roles of different acid sites in Beta zeolites with different particle sizes catalyzed liquid-phase transalkylation of diethylbenzene with benzene

Catalysis Science & Technology ◽

10.1039/d1cy01849c ◽

2021 ◽

Author(s):

Chuanyu Yang ◽

Zhongwen Dong ◽

Weifeng Chu ◽

Yanan Wang ◽

Dongpu Zhao ◽

...

Keyword(s):

Liquid Phase ◽

Acid Sites ◽

Zeolite Catalysts ◽

Beta Zeolite ◽

Particle Sizes ◽

Synthesis System ◽

Beta Zeolites

A series of Beta zeolite catalysts with controllable particle sizes and similar Si/Al ratios were prepared by introducing imidazole (IMD) into the synthesis system and used for a liquid-phase transalkylation...

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Kinetic Study of the Simultaneous Cracking of Paraffins and Methanol on HZSM-5 Zeolite Catalysts

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1564 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Diana Mier ◽

Andrés Tomás Aguayo ◽

Alaitz Atutxa ◽

Ana G Gayubo ◽

Javier Bilbao

Keyword(s):

Kinetic Model ◽

Catalyst Deactivation ◽

Fixed Bed ◽

Acid Catalyst ◽

Product Distribution ◽

Operating Conditions ◽

Zeolite Catalysts ◽

Fixed Bed Reactor ◽

Light Olefins ◽

Feed Temperature

A study has been carried out on the effect of acid catalyst properties and operating conditions (methanol/n-butane ratio in the feed, temperature, space time, time on stream) on the yield of light olefins (C2-C4) in the simultaneous cracking of n-butane and methanol. The operation has been carried out in an isothermal fixed bed reactor in the 400-575 °C range, using catalysts prepared based on HZSM-5 zeolites (with different Si/Al ratio), HY, Ni/HZSM-5 and SAPO-18. The results are evidence of a synergism between the transformation reactions of both reactants, whose consequence is an increase in the yield of olefins that correspond to the transformation of methanol and the cracking of n-butane. Furthermore, catalyst deactivation by coke is significantly attenuated compared to the corresponding transformation of methanol. Based on the effect of operating conditions on product distribution, a kinetic model is proposed by combining the schemes corresponding to the transformation of individual components.

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Acidity effects of K promoted Co-based catalyst with NH4OH addition of the impregnation solution for Fischer-Tropsch synthesis

MATEC Web of Conferences ◽

10.1051/matecconf/201926807001 ◽

2019 ◽

Vol 268 ◽

pp. 07001

Author(s):

Zaky Al Fatony ◽

Yosi Febriani ◽

IGBN Makertihartha ◽

Melia Laniwati Gunawan ◽

Subagjo

Keyword(s):

Catalyst Activity ◽

Fixed Bed ◽

Product Distribution ◽

Acid Sites ◽

Weak Acid ◽

Tropsch Synthesis ◽

Fixed Bed Reactor ◽

Impregnation Method ◽

Fischer Tropsch ◽

Fischer Tropsch Synthesis

Fischer-Tropsch synthesis (FTS) with cobalt-based catalyst has been developed to produce wax as a feedstock for further catalytic cracking. During catalyst preparation, NH4OH was added to the salt nitrate precursor to investigate the influence on catalyst acidity. Catalysts were prepared by the dry impregnation method and characterized by XRD, BET and NH3-TPD analyses. These properties were correlated with activity and selectivity of the catalyst. Activity tests showed CO and H2 conversion were in the range of 36.4% to 80.3% and 34.2% to 74.1% respectively. The cobalt particle size measurements exhibited 7.6-8.5 nm. The presence of weak acid sites on catalyst with large surface area and pore size is mainly responsible for obtaining high yields of C5+ hydrocarbon due to suppression of cracking properties. The product distribution showed a higher selectivity to C5+ in the range of 53.57% to 96.5%. In this study, FTS was evaluated by using fixed-bed reactor at 20 bar, 250 C, and WHSV of 1500 ml/g.cat/h-1.

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Deep Eutectic Solvents with Multiple Weak Acid Sites for Highly Efficient, Reversible and Selective Absorption of Ammonia

Separation and Purification Technology ◽

10.1016/j.seppur.2021.118791 ◽

2021 ◽

pp. 118791

Author(s):

Ning-Ning Cheng ◽

Zi-Liang Li ◽

Hong-Chao Lan ◽

Wen-Long Xu ◽

Wen-Jing Jiang ◽

...

Keyword(s):

Deep Eutectic Solvents ◽

Acid Sites ◽

Weak Acid ◽

Selective Absorption ◽

Highly Efficient

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Promotional Effects of Rare-Earth Praseodymium (Pr) Modification over MCM-41 for Methyl Mercaptan Catalytic Decomposition

Processes ◽

10.3390/pr9020400 ◽

2021 ◽

Vol 9 (2) ◽

pp. 400

Author(s):

Xiaohua Cao ◽

Jichang Lu ◽

Yutong Zhao ◽

Rui Tian ◽

Wenjun Zhang ◽

...

Keyword(s):

Dimethyl Sulfide ◽

Catalytic Decomposition ◽

Product Distribution ◽

Acid Sites ◽

Methyl Mercaptan ◽

Praseodymium Oxide ◽

X Ray ◽

Xps Characterization ◽

Temperature Programmed ◽

Mcm 41

Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2 adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectrometer (XPS), were carried out to analyze the physicochemical properties of material. XPS characterization results showed that praseodymium was presented on the modified catalyst in the form of praseodymium oxide species, which can react with coke deposit to prolong the catalytic stability until 120 h. Meanwhile, the strong acid sites were proved to be the main active center over the 10% Pr/MCM-41 catalyst by NH3-TPD results during the catalytic elimination of methyl mercaptan. The possible reaction mechanism was proposed by analyzing the product distribution results. The final products were mainly small-molecule products, such as methane (CH4) and hydrogen sulfide (H2S). Dimethyl sulfide (CH3SCH3) was a reaction intermediate during the reaction. Therefore, this work contributes to the understanding of the reaction process of catalytic decomposition methyl mercaptan and the design of anti-carbon deposition catalysts.

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Solvent-Free Synthesis of SAPO-34 Zeolite with Tunable SiO2/Al2O3 Ratios for Efficient Catalytic Cracking of 1-Butene

Catalysts ◽

10.3390/catal11070835 ◽

2021 ◽

Vol 11 (7) ◽

pp. 835

Author(s):

Xia Xiao ◽

Zhongliang Xu ◽

Peng Wang ◽

Xinfei Liu ◽

Xiaoqiang Fan ◽

...

Keyword(s):

Catalytic Cracking ◽

Acid Sites ◽

Solvent Free ◽

Zeolite Catalysts ◽

Light Olefins ◽

Molar Ratio ◽

Coordination Environment ◽

Starting Mixture ◽

Synthesis Methodology ◽

Solvent Free Synthesis

Solvent-free synthesis methodology is a promising technique for the green and sustainable preparation of zeolites materials. In this work, a solvent-free route was developed to synthesize SAPO-34 zeolite. The characterization results indicated that the crystal size, texture properties, acidity and Si coordination environment of the resulting SAPO-34 were tuned by adjusting the SiO2/Al2O3 molar ratio in the starting mixture. Moreover, the acidity of SAPO-34 zeolite was found to depend on the Si coordination environment, which was consistent with that of SAPO-34 zeolite synthesized by the hydrothermal method. At an SiO2/Al2O3 ratio of 0.6, the SP-0.6 sample exhibited the highest conversion of 1-butene (82.8%) and a satisfactory yield of light olefins (51.6%) in the catalytic cracking of 1-butene, which was attributed to the synergistic effect of the large SBET (425 m2/g) and the abundant acid sites (1.82 mmol/g). This work provides a new opportunity for the design of efficient zeolite catalysts for industrially important reactions.

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